More info on Radian Aerospace (Gary Hudson of Rotary Rocket and DC-X is involved). The patent discussed in the article: patents.google.com/patent/US20200…twitter.com/meharris/statu…
From Businessweek’s Mark Harristwitter.com/meharris/status/1333451938189361160Basic points:Radian just closed $20 million series ADeveloping catapult launched SSTO five person spaceplaneUses kerolox engines, have already conducted a firing near Seattle
OK, kerolox SSTO rocket plane. Fuel ratio of 95%.Was there some material science breakthrough? Can you build spaceships of hard light?
Quote from: Eerie on 11/30/2020 04:32 pmOK, kerolox SSTO rocket plane. Fuel ratio of 95%.Was there some material science breakthrough? Can you build spaceships of hard light?I mistakenly called it a catapult, but it is actually a "rocket sled" that is initiallly used to bring it up to speed before launch. so perhaps not a strict SSTO?
Hope they succeed!
Patent attached
SSTO with Kero/LOX? With wings and landing gear and a heat shield?I will criticize others when they say something is impossible (because there are many things that are possible that haven't been built yet). But I'm very, very confident when i say:This is not going to happen.
Quote from: Ronsmytheiii on 11/30/2020 04:41 pmQuote from: Eerie on 11/30/2020 04:32 pmOK, kerolox SSTO rocket plane. Fuel ratio of 95%.Was there some material science breakthrough? Can you build spaceships of hard light?I mistakenly called it a catapult, but it is actually a "rocket sled" that is initiallly used to bring it up to speed before launch. so perhaps not a strict SSTO?The sled brings it to plane take-off speed. So nothing, basically.
All time record for kerolox specific impulse: must be RD-0124, 362 seconds - in vaccuum. All time record propellant mass fraction: 0.962 - Titan 2 stage 1. Expendable, zero payload without a second stage. The margins are razor slim or non existing.
Hey, looks like our very own HMXHMX is part of this !
Face-shutoff pintle with pure film cooling. Interesting choice given those are not known for their efficiency. Chamber shouldn't have much fatigue issues though.
Quote from: Gliderflyer on 11/30/2020 07:13 pmFace-shutoff pintle with pure film cooling. Interesting choice given those are not known for their efficiency. Chamber shouldn't have much fatigue issues though.Isn't the pintle the only design that supposed to never had an issue with combustion instability? Attractive if you want a hassle free, quick to develop (and quite easily throttled) engine I imagine. You're point about efficiency does make it an odd choice to include in a patent. With mass growth and efficiency so critical in this application you'd expect them to go for the best they can find.
Was there some material science breakthrough?
In the past, using composites for the storage of cryogenic liquid fuel – liquid hydrogen, liquid oxygen, liquid methane – has been met with concern revolving around the potential for leaks, due to microcracking of traditional carbon/epoxy composite laminates at extremely low temperatures. A leap forward with the technology seems to be underway.
I've heard that about pintles before, but never from someone who worked on one (they tend to laugh at that). Face-shutoff is also annoying to get working from what I've heard, but I think Gary has done it before so he may have a head start.
Film cooling is the strangest choice to me. Armadillo did a similar cooling method, and the Isp hit was large.
The mention of an advanced carbon fiber LOx tank may suggest linerless to reduce weight?
Very crude calculations... 9.81*362*ln((200+4.5)/(11+4.5)) = 9161 m/s Let's suppose their rocket plane weights 200 mt (completely arbitrary number, but one has to start to speculate somewhere !) Payload is 4.5 mt : 10 000 pounds. Specific impulse: I retained the RD-0124 vacuum and record, since they have nozzles adapted to sea level conditions (otherwise, would have been 340 seconds at sea level for kerolox) From there it is pretty simple: the empty weight must be 11 mt. If they bust that limit : the thing won't go into orbit anymore !
But what is the staging velocity for the rocket sled? I believe that the land based manned speed record is subsonic but unmanned rocket sleds have reached up to mach 8. It probably doesn't make sense to make a manned version from the start.
Quote from: ncb1397 on 12/01/2020 05:43 pmBut what is the staging velocity for the rocket sled? I believe that the land based manned speed record is subsonic but unmanned rocket sleds have reached up to mach 8. It probably doesn't make sense to make a manned version from the start.Good question. But you're wrong about the land speed record. As of 1997 Thrust SSC reached 763.035mph, or M1.016 at sea level. That said transonic drag around M0.9-1.1 is going to be severe at ground level. Requiring the design be crewed from the start (like the Shuttle, but unlike every other crewed space vehicle) would be a majorhandicap in development, and is simply unnecessary (unless you have a NASA center that demands the design needs to be crewed from the start )
300mph is all the sled goes up to. That's a very good number, IMHO. Any higher than that and airframe stresses increase, and you start getting local supersonic flow. And to go 600mph, you'd need to quadruple your track length (for the same acceleration).
Yes the land speed record (absolute, unmanned, all vehicles) is some kind of rocket sled, circa mach 8. https://en.wikipedia.org/wiki/Rocket_sledMach 8.5 - but I'm not sure it is applicable to throwing a rocketplane !
It's easier to get higher mass ratios with denser propellants, at least this has a better chance of happening than any hydrogen SSTO.
In some ways sled launch is a good compromise. Not as fixed as needing a track so you can launch in any direction (that's a good thing) and provided you're running over bedrock you can make the sled almost as big as you like (if you can find jet or rocket engines big enough), whereas launch aircraft size is a major constraint for air launch.
Quote from: john smith 19 on 12/03/2020 07:36 amIn some ways sled launch is a good compromise. Not as fixed as needing a track so you can launch in any direction (that's a good thing) and provided you're running over bedrock you can make the sled almost as big as you like (if you can find jet or rocket engines big enough), whereas launch aircraft size is a major constraint for air launch. All of the hypersonic (and for that matter supersonic) sleds have been on tracks. The only reason they're 'sleds' on 'tracks' and not on 'rails' is because they slide on bearing surfaces rather than roll on wheels.
Has anyone every actually built a high speed unfixed "floating" sled before? Something that can run on salt flats or lakebeds? Say a hovercraft, or a ground effect PAR-WIG? Some old concept designs for an SSTO had a "flying" jet sled/platform that resembled a WIG.
All of the hypersonic (and for that matter supersonic) sleds have been on tracks. The only reason they're 'sleds' on 'tracks' and not on 'rails' is because they slide on bearing surfaces rather than roll on wheels.
All time record for kerolox specific impulse: must be RD-0124, 362 seconds - in vaccuum. All time record propellant mass fraction: 0.962 - Titan 2 stage 1. Expendable, zero payload without a second stage.
The margins are razor slim or non existing.
I did a quick straw pole of empty/gross weights for some combat aircraft and it came up as around 38-45%, even for ones as "sporty" as the Talon T-38, a supersonic trainer with pretty much no payload but the instructor and trainee. The Virgin Global Challenger aircraft (an engine, air bubble and wings wrapped round a humongous fuel tank) gave a design of 17% structure, so better is possible if you sacrifice other things. Rockets can give you 10x the T/W ratio of SoA turbofans, OTOH they also give you roughly 1/10 the Isp So can you wrap 413247Kg of propellant in 32252Kg of structural mass (including escape module) to hold 4500 of payload? that's about 2.37x better than the Virgin Global Flyer managed.
negatives-internal fuel tank that needs to be covered in greater amount of TPS for re-entry.
Figure 2 in the report reckons Wings need 38.2%, body is 28.4% and tail takes 3.6% of the dry weight of the vehicle. "Propulsion" (SSME, OMS/RCS, pressurization and prop feed system) is 18.8%
What is really crazy is that the percentages, above, are "slices" or "bits" of... 5% of the GLOW (Gross Lift Off Weight) since 95% else is the propellant in the tanks.
I'm the proud owner of a Fiat Grande Punto since 2011. A very nice car. It weights 1000 kg. And since the tank hold 45 L of gasoline, that must be 40 kg in mass. 40 kg out of 1000 kg. Leaves plenty of margin. Now If I applied "all-rocket SSTO" numbers to it... the gasoline in the tank would represents 950 kg. No kidding.
Brilliant and interesting posts there. Couldn't remember if I had downloaded that RASV report or not, so downloaded it again.
"Takes the SSTO, standing still on the pad, ready to launch. The propellant tanks are full. Well - 95% of the mass must be raw propellants. Otherwise, kiss Earth orbit goodbye ! Sooo...- the tanks around the propellants, - and the SSTO around the tanks, - with the payload (obviously !) ...are allocated 5%. Five percent. And if you miss, and get 7% or even 6%, the SSTO falls short of orbit.
That isn't necessarily true. I graphed both 9000 m/s and 9300 m/s and as long as you can get average ISP of around ~330, dry mass around ~6% is sufficient if 9300 m/s is requires and ~7% is sufficient if 9000 m/s is required. Merlin 1D sea level performance is 282 seconds and vacuum performance is 311, but the vacuum variant gets about 348. RD-180 is between 311(sea level) and 338 (vacuum), so getting 330 average shouldn't be impossible. Even at 320, you still can go to 5.5-6% (of course, lower is better).
edit: average isp isn't really the best way to describe the above. Two systems that have the same average isp might perform somewhat differently from a change in velocity perspective. But starting at the RD-180 sea level isp of 311 and linearly moving to 338 over the burn, a vehicle that is 6% dry weight and 94% propellant gets about 9100 m/s. Which, adding 300 mph or 135 m/s for the rocket sled, could probably get you to orbit (dependent on gravity/drag loses and latitude).
What was the Delta II "recipe" to get that low - "only" 1150 m/s of gravity losses ?
Quote from: libra on 12/09/2020 03:10 pmWhat was the Delta II "recipe" to get that low - "only" 1150 m/s of gravity losses ? Super high TWR early in flight, with lots of SRBs (including air-lit ones in some configurations.)Having wings (even with a mediocre TWR) should actually help gravity losses significantly as the lift offsets gravity early in flight when losses would otherwise be the highest. Recall that the wings on the Pegasus rocket actually increased the payload capacity, despite the added mass.
Thanks you all for these numbers. No dogma for me, really - 6% , 7%, no problem. Still a daunting mass fraction. Although JS19 contenair and soda can examples are interestings. What was the Delta II "recipe" to get that low - "only" 1150 m/s of gravity losses ? With the rocket equation, even 200 m/s can make a difference... and there, we have 400 m/s variations, 8800 to 9200 m/s... Gravity losses - such a tricky thing.
Super high TWR early in flight, with lots of SRBs (including air-lit ones in some configurations.)Having wings (even with a mediocre TWR) should actually help gravity losses significantly as the lift offsets gravity early in flight when losses would otherwise be the highest. Recall that the wings on the Pegasus rocket actually increased the payload capacity, despite the added mass.
Quote from: libra on 12/09/2020 03:10 pmThanks you all for these numbers. No dogma for me, really - 6% , 7%, no problem. Still a daunting mass fraction. Although JS19 contenair and soda can examples are interestings. What was the Delta II "recipe" to get that low - "only" 1150 m/s of gravity losses ? With the rocket equation, even 200 m/s can make a difference... and there, we have 400 m/s variations, 8800 to 9200 m/s... Gravity losses - such a tricky thing.You'll note that it has the 2nd highest drag losses of the vehicles, suggesting it spends an extended amount of time in the atmosphere, but its steering losses are very low.
given the displacement formulas= ut + (1/2)a*t*tu or initial velocity is zero for a VTO rocket and a * t is velocity. So, we can simplify to s= (1/2) *v * t or v = 2s/t with s being displacement (in this case the altitude of the rocket). So, we know that for a certain altitude, the velocity for a linearly accelerating vehicle is inverse to the time it takes to get there (half the time, double the velocity). We also know that drag scales to the square of the velocity, so if you half the time, you are actually increasing the instantaneous drag at a certain altitude by 4x. Total drag would be average drag * time over the course of flight, so halving time as a result of increasing thrust isn't going to be enough to overcome 4x the instantaneous drag as a result of halving the amount of time. So, there is a trade off somewhat between aerodynamic losses and gravity losses. Your aerodynamic losses will increase if you increase your thrust as gravity losses decrease. This explains why the low gravity loses are correlated with higher aerodynamic losses. But the higher aerodynamic losses isn't associated with more time in the atmosphere, the higher thrust rocket spends less time in the atmosphere.At least, that is what I could come up with. Feel free to point out any logical/math/physics errors.
All of which I presume Radian have been doing, although the choice of kerosene still baffles me.
Using the delta-V of multi-stage vehicles for SSTO is misleading, since the acceleration profiles are quite different compared to a SSTO. In general, the lower the Isp, the lower the delta-V required to get into orbit. This comes from a number of factors. One is that air drag deceleration is lower due to the higher vehicle mass for the same cross sectional area. Second is that maximum acceleration is reached faster due to the higher propellant mass to inert mass ratio.For hydrolox, vacuum delta-V going into a 80x185 km orbit is about 9340 m/s, compared to 9090 m/s for kerolox, a 250 m/s saving. For RS-25, vacuum Isp is 4444 m/s, which gives a propellant mass fraction of 87.8%, however for every kg of final mass you need about 20 L of propellant, or 20 L/kg. For RD-180 with a vacuum Isp of 3325 m/s, the propellant mass fraction is 93.5%, however you only need 14 L/kg, 30% less than hydrolox! However, you do need higher thrust, and thus heavier engines due to the higher lift-off mass.This means that for the same tank volume, hydrolox in general performs much worse than kerolox, since the final mass will be 30% less compared to kerolox!
Thanks you all for these numbers. No dogma for me, really - 6% , 7%, no problem. Still a daunting mass fraction. Although JS19 contenair and soda can examples are interestings.
With the rocket equation, even 200 m/s can make a difference... and there, we have 400 m/s variations, 8800 to 9200 m/s... Gravity losses - such a tricky thing.
Makes sense when you consider the fuel tanks are the wings (the oxygen tank is in the main body). Integrating RP-1/kerosene/Jet-A type fuels into wings is a solved problem even for composite wings. On the other hand, programs like the X-33 had problems with the combination of complex shapes, composite materials and cryogenic fuels. Using a denser fuel also potentially gives you some more flexibility in defining the wing's shape and size. It also makes more sense from a structural stand point, kerolox has a lower fuel to oxidizer ratio, meaning more weight is in the wings where the lift is generated and less weight is in the body that has to be supported from the lift generated at the wings.
A Washington-state based aerospace company has exited stealth mode by announcing plans to develop one of the holy grails of spaceflight—a single-stage-to-orbit space plane. [...]The current design of Radian One calls for taking up to five people and 5,000 pounds of cargo into orbit. The vehicle would have a down-mass capability of about 10,000 pounds and be powered by three liquid-fueled engines.
taking up to five people and 5,000 pounds of cargo
Quotetaking up to five people and 5,000 pounds of cargoHopefully not both at once. Cargo vehicles with crew cabins are a terrible idea.
Radian announces plans to build one of the holy grails of spaceflight:https://arstechnica.com/science/2022/01/radian-announces-plans-to-build-one-of-the-holy-grails-of-spaceflight/Quote from: Eric BergerA Washington-state based aerospace company has exited stealth mode by announcing plans to develop one of the holy grails of spaceflight—a single-stage-to-orbit space plane. [...]The current design of Radian One calls for taking up to five people and 5,000 pounds of cargo into orbit. The vehicle would have a down-mass capability of about 10,000 pounds and be powered by three liquid-fueled engines. https://twitter.com/SciGuySpace/status/1483803673687953413
Radian Aerospace said it is deep into the design of an airplane-like vehicle that could take off from a runway, ignite its rocket engines, spend time in orbit, and then return to Earth and land on a runway.
powered by three liquid-fueled engines [...] At full power, this cryogenic-fueled engine will have a thrust of about 200,000 pounds.
Space launch companies also now regularly "super chill" their liquid propellants to gain more performance during flight, which Radian plans to do.
While nothing closed to hard numbers, the article drops some hints that rules out some options:QuoteRadian Aerospace said it is deep into the design of an airplane-like vehicle that could take off from a runway, ignite its rocket engines, spend time in orbit, and then return to Earth and land on a runway.No rocket-sled launch
Quote from: edzieba on 01/19/2022 05:17 pmWhile nothing closed to hard numbers, the article drops some hints that rules out some options:QuoteRadian Aerospace said it is deep into the design of an airplane-like vehicle that could take off from a runway, ignite its rocket engines, spend time in orbit, and then return to Earth and land on a runway.No rocket-sled launchTheir website says "sled-assist takeoff"
Quote from: DreamyPickle on 01/19/2022 05:53 pmQuote from: edzieba on 01/19/2022 05:17 pmWhile nothing closed to hard numbers, the article drops some hints that rules out some options:QuoteRadian Aerospace said it is deep into the design of an airplane-like vehicle that could take off from a runway, ignite its rocket engines, spend time in orbit, and then return to Earth and land on a runway.No rocket-sled launchTheir website says "sled-assist takeoff"Jet sled then?
While nothing closed to hard numbers, the article drops some hints that rules out some options:QuoteRadian Aerospace said it is deep into the design of an airplane-like vehicle that could take off from a runway, ignite its rocket engines, spend time in orbit, and then return to Earth and land on a runway.No rocket-sled launchQuotepowered by three liquid-fueled engines [...] At full power, this cryogenic-fueled engine will have a thrust of about 200,000 pounds.Not Kerolox, somewhere in the range of 0.9MN per engine or ~2.7MN for the vehicle.Quote Space launch companies also now regularly "super chill" their liquid propellants to gain more performance during flight, which Radian plans to do.Sub-chilled propellants.
I've said this elsewhere. If this is possible it would have been done by now. You can't have any meaningful payload to orbit using one stage. Unless you resort to the very difficult method of using atmospheric oxygen in the lower atmosphere.
Quote from: daedalus1 on 01/20/2022 06:33 amI've said this elsewhere. If this is possible it would have been done by now. You can't have any meaningful payload to orbit using one stage. Unless you resort to the very difficult method of using atmospheric oxygen in the lower atmosphere.X-33, which would have delivered meaningful payload to orbit with one stage, was arbitrarily canceled by political/bureaucratic nonsense when it was practically 95% complete with every immediate problem solved. N1, a potentially great rocket, was canceled because of politics, funding, and the death of its creator. Energia and Buran, both potentially extraordinary and better than anything operating at the time, died because of funding and the collapse of the USSR. There are a thousand other paper or incomplete rockets that were never realized.Really one of the weakest arguments out there to say that good or possible ideas "would have been done by now" in the context of spaceflight - especially post-Apollo American spaceflight, where most rockets fielded since the 70s have been shaped by shareholders, politicians, and bureaucrats as much as engineers and sound logic.The odds are absolutely stacked against Radian but let's not try to argue that any rocket concept that hasn't been made real by 2022 is inherently a bad idea.
Quote from: vaporcobra on 01/20/2022 08:08 amQuote from: daedalus1 on 01/20/2022 06:33 amI've said this elsewhere. If this is possible it would have been done by now. You can't have any meaningful payload to orbit using one stage. Unless you resort to the very difficult method of using atmospheric oxygen in the lower atmosphere.X-33, which would have delivered meaningful payload to orbit with one stage, was arbitrarily canceled by political/bureaucratic nonsense when it was practically 95% complete with every immediate problem solved. N1, a potentially great rocket, was canceled because of politics, funding, and the death of its creator. Energia and Buran, both potentially extraordinary and better than anything operating at the time, died because of funding and the collapse of the USSR. There are a thousand other paper or incomplete rockets that were never realized.Really one of the weakest arguments out there to say that good or possible ideas "would have been done by now" in the context of spaceflight - especially post-Apollo American spaceflight, where most rockets fielded since the 70s have been shaped by shareholders, politicians, and bureaucrats as much as engineers and sound logic.The odds are absolutely stacked against Radian but let's not try to argue that any rocket concept that hasn't been made real by 2022 is inherently a bad idea.Well let's stick to the post subject.X33 wasn't SSTO it was a technology demonstrator for Venture Star and had multiple failures and problems including cracking in the tanks. My comment is based on physics. 1 G is right on the edge of getting to orbital speed with the whole body and a significant payload unless you can scoop some oxygen from the air (Skylon).I wish them the best of luck in this project as it would be a significant game changer.
Quotepowered by three liquid-fueled engines [...] At full power, this cryogenic-fueled engine will have a thrust of about 200,000 pounds.Not Kerolox, somewhere in the range of 0.9MN per engine or ~2.7MN for the vehicle.
A few notable details I gleaned from a quick skim through the patent:The Launch Sled-Acts as a TEL, with propellant feed lines and physical supports attached to the vehicle-Has its own engines, which fire in addition to the vehicle's engines-May feed propellant into the vehicle to replace that burned by the vehicle's engines during the takeoff run (quick disconnect before takeoff)-May rotate the vehicle from an initial low-drag configuration to a nose-up takeoff configuration-Has a braking system that can bring the whole vehicle to a halt in case of emergency (the takeoff run is one long engine checkout)-Provides some initial velocity, but more importantly, reduces the demands on (and thus mass of) the landing gear, since the vehicle is only on its gear when its tanks are empty for landingThe Vehicle-Designed for crew and low-mass cargo, "about 5-10000 pounds to LEO" (2.3-4.5 mT), claims the F9 is overpowered for these applications-Fuel is JET-A, oxidizer is LOX-Main engines have a "Tripped Area Ratio"/"Tripped Flow", which changes from about 33:1 to about 60:1 in-flight, allowing good sea-level and vacuum performance (no details on how exactly this would be implemented)-Separate set of OMS engines above the main engines, potentially pressure-fed LOX/CNG gas-gas thrusters (I know who might be developing one of those)-In addition to the shuttle's abort modes (ATO, AOA, Downrange, and RTLS), the entire cabin can detach and perform a powered abort (picture attached), using "bipropellant thrusters" and fuel tanks in the nose, plus chutes for recovery. Intact abort modes would require venting fuel before landing due to the low-rated gear.-Material selection hasn't been made yet, but short-lists composites, Aluminum, Titanium, and Stainless Steel. Heat shield material also not selected yet, but TUFROC given as example.
-Main engines have a "Tripped Area Ratio"/"Tripped Flow", which changes from about 33:1 to about 60:1 in-flight, allowing good sea-level and vacuum performance (no details on how exactly this would be implemented)
Quote from: edzieba on 01/19/2022 05:17 pmQuotepowered by three liquid-fueled engines [...] At full power, this cryogenic-fueled engine will have a thrust of about 200,000 pounds.Not Kerolox, somewhere in the range of 0.9MN per engine or ~2.7MN for the vehicle.Last I checked, Propane was one of the dream fuels of those who were studying SSTOs. It's cryogenic, but has a density much closer to RP1 than even Methane. It's what I'd put my money on.
Quote from: JEF_300 on 01/20/2022 06:36 pmQuote from: edzieba on 01/19/2022 05:17 pmQuotepowered by three liquid-fueled engines [...] At full power, this cryogenic-fueled engine will have a thrust of about 200,000 pounds.Not Kerolox, somewhere in the range of 0.9MN per engine or ~2.7MN for the vehicle.Last I checked, Propane was one of the dream fuels of those who were studying SSTOs. It's cryogenic, but has a density much closer to RP1 than even Methane. It's what I'd put my money on. Not strictly speaking cryogenic. It is a liquid at room temperature under a modest amount of pressure. You can buy LPG (essentialy liquid propane) in any small town in the US and you can find a "propane tank" under the grill in the back yard of a lot of suburban homes. I assume you can chill to to increase the density, but I don't know that and I don't know how much it would help.
X-33, which would have delivered meaningful payload to orbit with one stage, was arbitrarily canceled by political/bureaucratic nonsense when it was practically 95% complete with every immediate problem solved. N1, a potentially great rocket, was canceled because of politics, funding, and the death of its creator. Energia and Buran, both potentially extraordinary and better than anything operating at the time, died because of funding and the collapse of the USSR. There are a thousand other paper or incomplete rockets that were never realized.
…Material selection hasn't been made yet, but short-lists composites, Aluminum, Titanium, and Stainless Steel. …
QuoteX-33, which would have delivered meaningful payload to orbit with one stage, was arbitrarily canceled by political/bureaucratic nonsense when it was practically 95% complete with every immediate problem solved. N1, a potentially great rocket, was canceled because of politics, funding, and the death of its creator. Energia and Buran, both potentially extraordinary and better than anything operating at the time, died because of funding and the collapse of the USSR. There are a thousand other paper or incomplete rockets that were never realized.Nonsense all the way.
It's really not. I mean, I'm not gonna say that X-33 would've worked or anything; because really, who could know. But the fact remains that every attempt at an SSTO I am aware of was cancelled because of budget reasons rather than technical ones.
Quote from: daedalus1 on 01/20/2022 08:22 amQuote from: vaporcobra on 01/20/2022 08:08 amQuote from: daedalus1 on 01/20/2022 06:33 amI've said this elsewhere. If this is possible it would have been done by now. You can't have any meaningful payload to orbit using one stage. Unless you resort to the very difficult method of using atmospheric oxygen in the lower atmosphere.X-33, which would have delivered meaningful payload to orbit with one stage, was arbitrarily canceled by political/bureaucratic nonsense when it was practically 95% complete with every immediate problem solved. N1, a potentially great rocket, was canceled because of politics, funding, and the death of its creator. Energia and Buran, both potentially extraordinary and better than anything operating at the time, died because of funding and the collapse of the USSR. There are a thousand other paper or incomplete rockets that were never realized.Really one of the weakest arguments out there to say that good or possible ideas "would have been done by now" in the context of spaceflight - especially post-Apollo American spaceflight, where most rockets fielded since the 70s have been shaped by shareholders, politicians, and bureaucrats as much as engineers and sound logic.The odds are absolutely stacked against Radian but let's not try to argue that any rocket concept that hasn't been made real by 2022 is inherently a bad idea.Well let's stick to the post subject.X33 wasn't SSTO it was a technology demonstrator for Venture Star and had multiple failures and problems including cracking in the tanks. My comment is based on physics. 1 G is right on the edge of getting to orbital speed with the whole body and a significant payload unless you can scoop some oxygen from the air (Skylon).I wish them the best of luck in this project as it would be a significant game changer.Airbreathing doesn’t buy you that much. Dry mass is actually most strongly related to propellant VOLUME (and less so to propellant mass). Skylon has to carry an enormous volume of liquid hydrogen and has a high dry mass because of it.In fact, I seem to recall HMXHMX saying that given the mass ratios skylon was proposing, it may actually be easier to make a SSTO using denser fuels without airbreathing than a SSTO using hydrogen airbreathing plus hydrolox….…and here we are!Dunn’s table of densified propellants for SSTO performance shows densified propylene/oxygen to be among the highest performance combinations for SSTO, beating hydrolox by a lot and even densified kerolox and methalox. Only more exotic propellants like cyclopropane improve on it, and then only slightly.So I wonder if they’ll use something like densified propylene and oxygen. Or perhaps something like syntin (which is chemically related to cyclopropane) which the Russians/Soviets sometimes use(d).The launch sled is a good idea, especially as it helps enable aborting the takeoff. Big brakes to stop after coming up to speed would be not viable for a SSTO vehicle without a sled. And getting it up to transonic speeds or so would be a very nice little assist as well, considering rockets burn up a lot of their propellant just to get off the pad. Rockets are least efficient at low speeds, so that small assist goes a long way.And with the sled, they can also do captive tests of the vehicle without actually taking flight. That is easier from a regulatory standpoint (I don’t think it needs regulatory approval from the FAA), and they can even do tests before the wings are ready. They could do non-destructive qualifying tests on the airframe and propulsion systems. It’s actually a pretty good idea, to be honest. To enable the same thing without wings would mean you’d have to build a vertical launch assist tower, which would be a lot harder and more expensive.It’s not as silly as it might seem. The launch sled buys you a lot. Using densified propellants buys you a LOT. (Although we don’t know what they’re using… if it’s hydrolox like X-33, then they will struggle. It’s one of the worst SSTO propellants to use because of its low density.)I do hope they consider a small payload assist motor. Would make it way easier to close the design early on. Could be just a STAR motor from ATK/NG or something. Even 1-2km/s for the kick stage would help improve margins by a HUGE amount. (Although recovering the vehicle may be tough, but wings make fly back easier)At the limit they could go with super conservative margins and just do like a big Lynx Mark III approach, launching smallsats with a sizable payload assist upper stage after getting above the Karman Line. That would be super easy to make close. They could use massive margins everywhere as it’d be basically a three stage to orbit vehicle.
Quote from: libra on 01/20/2022 06:55 pmQuoteX-33, which would have delivered meaningful payload to orbit with one stage, was arbitrarily canceled by political/bureaucratic nonsense when it was practically 95% complete with every immediate problem solved. N1, a potentially great rocket, was canceled because of politics, funding, and the death of its creator. Energia and Buran, both potentially extraordinary and better than anything operating at the time, died because of funding and the collapse of the USSR. There are a thousand other paper or incomplete rockets that were never realized.Nonsense all the way.It's really not. I mean, I'm not gonna say that X-33 would've worked or anything; because really, who could know. But the fact remains that every attempt at an SSTO I am aware of was cancelled because of budget reasons rather than technical ones.
Quote from: JEF_300 on 01/20/2022 07:04 pmIt's really not. I mean, I'm not gonna say that X-33 would've worked or anything; because really, who could know. But the fact remains that every attempt at an SSTO I am aware of was cancelled because of budget reasons rather than technical ones.I honestly disagree here. X-33 had massive. MASSIVE technical problems that were unresolved. If they hadn’t had such issues, it’s very likely it wouldn’t have faced those financial issues.In a way, saying that they all failed due to financial issues is kinda like saying a car crash victim died because their heart stopped. Like, kinda true, but that’s only the proximate cause, not the root cause. Could’ve still shocked that dead guy’s heart and kept it limping along, but as we know from Blue Origin, sometimes no amount of money is enough to solve technical problems any faster.
Quote from: JEF_300 on 01/20/2022 07:04 pmIt's really not. I mean, I'm not gonna say that X-33 would've worked or anything; because really, who could know. But the fact remains that every attempt at an SSTO I am aware of was cancelled because of budget reasons rather than technical ones.I'm not completely disagreeing with you, but development budget and technical difficulty are not independent of each other.
If this is possible it would have been done by now. You can't have any meaningful payload to orbit using one stage.
Quote from: Robotbeat on 01/20/2022 07:55 pmQuote from: JEF_300 on 01/20/2022 07:04 pmIt's really not. I mean, I'm not gonna say that X-33 would've worked or anything; because really, who could know. But the fact remains that every attempt at an SSTO I am aware of was cancelled because of budget reasons rather than technical ones.I honestly disagree here. X-33 had massive. MASSIVE technical problems that were unresolved. If they hadn’t had such issues, it’s very likely it wouldn’t have faced those financial issues.In a way, saying that they all failed due to financial issues is kinda like saying a car crash victim died because their heart stopped. Like, kinda true, but that’s only the proximate cause, not the root cause. Could’ve still shocked that dead guy’s heart and kept it limping along, but as we know from Blue Origin, sometimes no amount of money is enough to solve technical problems any faster.Quote from: groundbound on 01/20/2022 07:40 pmQuote from: JEF_300 on 01/20/2022 07:04 pmIt's really not. I mean, I'm not gonna say that X-33 would've worked or anything; because really, who could know. But the fact remains that every attempt at an SSTO I am aware of was cancelled because of budget reasons rather than technical ones.I'm not completely disagreeing with you, but development budget and technical difficulty are not independent of each other.I'd like to point us back to the post that started this for a moment.Quote from: daedalus1 on 01/20/2022 06:33 amIf this is possible it would have been done by now. You can't have any meaningful payload to orbit using one stage.This suggests that's it is impossible - literally, technically, physically, scientifically, mathematically, etc. - impossible to build an SSTO (with meaningful payload). We don't know that that is true, because none has ever finished.And sure, I agree that it's extremely hard technically. And I absolutely agree that the budget issues are related to it being so technically difficult. In fact, I think it's fair to say that it may be that building an SSTO is so hard technically that it is therefore financially impossible. But that's not the same thing as being "actually" impossible, at least in the way that term is generally used. And that is what I'm taking exception to. I mean, if we consider things that are financially impossible to be "actually" impossible, then wouldn't it be fair to say that a crewed Mars mission is impossible. Surely, if it was at all possible to justify spending that much on such a mission, it would've happened by now? Perhaps even a return to the Moon is impossible, by this measure. Over the years, there have probably been just as many attempts to return to the Moon as SSTOs, and yet it's never panned out, for much the same reasons.EDIT: I hate that we've dragged the thread off topic like this, but it was always gonna happen on an SSTO thread, so perhaps better to do it early.
On the actual topic of Radian's SSTO, I think it is a much more plausible proposal than most have given it credit for. - It uses engines of a manageable size to develop. - It's using a denser propellant than Hydrogen, as the SSTO experts seem to have decided is best. - This seems to avoid the classic SSTO trap of assuming that some wonder technology is going to magically make it all work. - Aerospace technology in general, and materials science in particular, has advanced dramatically since the last major attempts in the late 90s. Hopefully that means that the margins are more manageable than razor thin. Or, at least the very least are back-of-the-razorblade thin rather than edge-of-the-razorblade thin.I'd suggest that it's a good deal more plausible a vehicle than past SSTOs, at the very least.
(Although we don’t know what they’re using… if it’s hydrolox like X-33, then they will struggle. It’s one of the worst SSTO propellants to use because of its low density.)
The biggest issue is heat shield, how reuseable will be. Lighter it is shorter its life before needing refurbishing. Rest of dry mass design is well understood. Shuttle and X37 are the only reuseable winged vehicles with any orbital reuse history. How is X37 heat shield holding up?Sent from my SM-G570Y using Tapatalk
Quote from: TrevorMonty on 01/20/2022 10:53 pmThe biggest issue is heat shield, how reuseable will be. Lighter it is shorter its life before needing refurbishing. Rest of dry mass design is well understood. Shuttle and X37 are the only reuseable winged vehicles with any orbital reuse history. How is X37 heat shield holding up?Sent from my SM-G570Y using TapatalkI'd imagine the X-37B's heat shield is doing much better than Radian One's would, since X-37B is a much smaller vehicle (on account of not needing to get itself into space).
Quote from: Craftyatom on 11/30/2020 05:55 pm…Material selection hasn't been made yet, but short-lists composites, Aluminum, Titanium, and Stainless Steel. …Lol, basically any possible aerospace structural material.
The launch sled is a good idea, especially as it helps enable aborting the takeoff. Big brakes to stop after coming up to speed would be not viable for a SSTO vehicle without a sled. And getting it up to transonic speeds or so would be a very nice little assist as well, considering rockets burn up a lot of their propellant just to get off the pad. Rockets are least efficient at low speeds, so that small assist goes a long way.And with the sled, they can also do captive tests of the vehicle without actually taking flight. That is easier from a regulatory standpoint (I don’t think it needs regulatory approval from the FAA), and they can even do tests before the wings are ready. They could do non-destructive qualifying tests on the airframe and propulsion systems. It’s actually a pretty good idea, to be honest. To enable the same thing without wings would mean you’d have to build a vertical launch assist tower, which would be a lot harder and more expensive.
Quote from: JEF_300 on 01/20/2022 08:48 pmOn the actual topic of Radian's SSTO, I think it is a much more plausible proposal than most have given it credit for. - It uses engines of a manageable size to develop. - It's using a denser propellant than Hydrogen, as the SSTO experts seem to have decided is best. - This seems to avoid the classic SSTO trap of assuming that some wonder technology is going to magically make it all work. - Aerospace technology in general, and materials science in particular, has advanced dramatically since the last major attempts in the late 90s. Hopefully that means that the margins are more manageable than razor thin. Or, at least the very least are back-of-the-razorblade thin rather than edge-of-the-razorblade thin.I'd suggest that it's a good deal more plausible a vehicle than past SSTOs, at the very least.Any SSTO vehicle will need to have empty weight under 5% of the all up launch weight. That is still hugely difficult.
Hah. Not sure about that but the team does have 1-2 things up their sleeve technically that haven’t been considered before. When those features are known by the wider community, I think the viability of their approach will be better understood. Still a very hard problem though.
the team does have 1-2 things up their sleeve technically
Put otherwise: if we suppose the Radian rocketplane weights 200 tons ready for takeoff, then 190 tons must be kerosene and LOX inside the tanks.The "physical" rocketplane with the payload inside must be 10 metric tons.
Remember, Earth orbit for kerolox is (roughly) 9400 m/s - or bust. Not 9250 m/s, not 9000 m/s: 9400. Any small "gap" and its over.
What I don't understand is what does SSTO buy you over a streamlined TSTO system that's compromised of two independent rapidly reusable vehicles.[ . . . ]I see the allure when compared with a traditional "pieces fall off" type rocket, but I just don't see the motivation at the present time.
Quote from: meekGee on 01/21/2022 04:29 amWhat I don't understand is what does SSTO buy you over a streamlined TSTO system that's compromised of two independent rapidly reusable vehicles.[ . . . ]I see the allure when compared with a traditional "pieces fall off" type rocket, but I just don't see the motivation at the present time.When reading about previous single-stage-to-orbit efforts, I have gotten the impression that the operation of stacking of multiple stages were at least seen as something slow and laborious. It seemed to me that the assumption was that stacking would take several days, perhaps even weeks, and thus be detrimental to rapid reflight. Possibly informed by e.g. the space shuttle, which needed to be moved to the separate Vehicle Assembly Building, mated to its very large and heavy SRBs, and then slowly transported on the crawler-transporter to the launch pad.What they wanted was "airliner-like operations", where the just-landed vehicle could just be hooked up to a tow truck, dragged to the launch pad, be raised to vertical, fuelled, and launched again within a few hours.(Admittedly, my impression of how stacking was seen, has been formed mostly by reading between the lines of third-party descriptions of those SSTO efforts.)But I think we can agree that at assumptions that stacking has to be slow, are incorrect. Properly designed, with both the first stage and the upper stage/spacecraft landing next to the launch pad, and things actually designed for easy and rapid mating, it should be possible to get them stacked and ready for reflight in a couple of hours.
What I don't understand is what does SSTO buy you over a streamlined TSTO system that's compromised of two independent rapidly reusable vehicles.I mean by definition you'll be lugging your first stage to orbit and then re-entering it.Not only will it be more complex and expensive, but you also won't have it back in 20 minutes to launch again..I see the allure when compared with a traditional "pieces fall off" type rocket, but I just don't see the motivation at the present time.
Quote from: lrk on 12/09/2020 03:33 pmHaving wings (even with a mediocre TWR) should actually help gravity losses significantly as the lift offsets gravity early in flight when losses would otherwise be the highest. Recall that the wings on the Pegasus rocket actually increased the payload capacity, despite the added mass. The lead developer for Pegasus answered questions on the development process on the Pegasus thread some years back. I recall coming across an old Pop Sci article written around the time the original version first launched which also talked about their approach Orbital was strapped for cash at the time. They'd gone in big developing the Inertial Upper Stage for the Shuttle then Challenger happened so were looking for a new project to use their rocket knowledge and get some cash in. IOW they wouldn't have added wings to the design unless it gave substantial benefits to justify having them made. Keep in mind the wing has no propellant storage or control surfaces (fins on the rear of the first stage provide those).
Having wings (even with a mediocre TWR) should actually help gravity losses significantly as the lift offsets gravity early in flight when losses would otherwise be the highest. Recall that the wings on the Pegasus rocket actually increased the payload capacity, despite the added mass.
1. The ability to operate from a runway, even if you have to drag a launch sled along with you to do it, dramatically simplifies your ground handling and infrastructure. It also gives you more flexibility when deciding where to launch from.
2. Being an SSTO, no time or money (money is the far more important part) has to be spent between flights on vehicle integration, only payload integration. Yes, stage integration has historically been far less efficient than it could be. That doesn't change the fact that no integration is still faster and cheaper, particularly since that means you don't need to build and/or maintain and/or travel-to the facilities needed for stage integration. (Unless you decided to use a launch sled, in which case I guess reintegration with the sled is basically stage integration. I really don't like the sled.)
3. Even SpaceX isn't seriously consider launching the same vehicle more than once a day, so having to wait at least 90 minutes to get the vehicle back is hardly an issue.
4. This is in some ways more of an idle thought than a point. I would also think that a reusable TSTO should be inherently simpler than an SSTO. That said, the main example we have of a RTSTO design is Starship, which is using the most complicated rocket engine ever developed. Only time will tell, but it may be the most teams designing RTSTOs willingly give up their simplicity advantage in favor of further boosting their performance advantage.
Also, between the sled probably needing to be on rails, and the runway needing to support extreme heat loads, you're not taking this rocket sled to an arbitrary runway: it's fixed to a single launch site, same as the launch tower.
Quote from: JEF_300 on 01/21/2022 08:23 pm1. The ability to operate from a runway, even if you have to drag a launch sled along with you to do it, dramatically simplifies your ground handling and infrastructure. It also gives you more flexibility when deciding where to launch from.How is a rocket sled cheaper than a launch tower? The tower is a single static piece of infrastructure, it doesn't need to move at supersonic speeds, so I would imagine it's much cheaper to build and maintain. And you'd need the same fueling infrastructure in either case.
Quote from: JEF_3002. Being an SSTO, no time or money (money is the far more important part) has to be spent between flights on vehicle integration, only payload integration. Yes, stage integration has historically been far less efficient than it could be. That doesn't change the fact that no integration is still faster and cheaper, particularly since that means you don't need to build and/or maintain and/or travel-to the facilities needed for stage integration. (Unless you decided to use a launch sled, in which case I guess reintegration with the sled is basically stage integration. I really don't like the sled.)The question is whether the extra refurbishment necessary because the entire vehicle went to space and not just the much-smaller upper stage is more time-consuming and expensive than using a crane to stack a TSTO back together. My expectation would be "yes."
Looks interesting, wish Gary and all the other team members good luck!
Quote from: meekGee on 01/21/2022 04:29 amWhat I don't understand is what does SSTO buy you over a streamlined TSTO system that's compromised of two independent rapidly reusable vehicles.I mean by definition you'll be lugging your first stage to orbit and then re-entering it.Not only will it be more complex and expensive, but you also won't have it back in 20 minutes to launch again..I see the allure when compared with a traditional "pieces fall off" type rocket, but I just don't see the motivation at the present time.1. The ability to operate from a runway, even if you have to drag a launch sled along with you to do it, dramatically simplifies your ground handling and infrastructure. It also gives you more flexibility when deciding where to launch from.2. Being an SSTO, no time or money (money is the far more important part) has to be spent between flights on vehicle integration, only payload integration. Yes, stage integration has historically been far less efficient than it could be. That doesn't change the fact that no integration is still faster and cheaper, particularly since that means you don't need to build and/or maintain and/or travel-to the facilities needed for stage integration. (Unless you decided to use a launch sled, in which case I guess reintegration with the sled is basically stage integration. I really don't like the sled.)3. Even SpaceX isn't seriously consider launching the same vehicle more than once a day, so having to wait at least 90 minutes to get the vehicle back is hardly an issue.4. This is in some ways more of an idle thought than a point. I would also think that a reusable TSTO should be inherently simpler than an SSTO. That said, the main example we have of a RTSTO design is Starship, which is using the most complicated rocket engine ever developed. Only time will tell, but it may be the most teams designing RTSTOs willingly give up their simplicity advantage in favor of further boosting their performance advantage.
Quote from: Robotbeat on 01/20/2022 01:10 pm(Although we don’t know what they’re using… if it’s hydrolox like X-33, then they will struggle. It’s one of the worst SSTO propellants to use because of its low density.)I'd caveat that statement re: low density of hydrolox with "when used at normal mixture ratios in normal rocket engines". With LOX-rich TAN, you could theoretically make a stage O/F ratio of 12-18:1 work (instead of the traditional 4-6:1), which would help bulk density a ton, at the cost of lower Isp during the boost phase (which does help lower gravity losses though).I do agree though that pure LOX/LH2 at traditional mixture ratios has crappier bulk density than you'd want for an SSTO. When Aerojet did their TAN papers, they also looked at tri-propellant TAN -- where the main chamber was LOX/LH2, and the TAN injection was LOX/Kero. IIRC, they showed that that tripropellant approach actually closed way better than either pure LOX/Kero or pure LOX/LH2 for an SSTO designs -- high thrust and high bulk density for the start, high Isp for the end, and overall a great T/W ratio on the engines in booster mode (especially compared to typical LOX/LH2 engines).Given that Radian hasn't publicly stated what their engines are using, it's possible they could be doing something clever/unusual like this. Though I kind of think they would've said so if they were, because that would make the whole concept seem more plausible.~Jon
TAV concept had a jet sled launch...
Quote from: jongoff on 01/20/2022 10:07 pmQuote from: Robotbeat on 01/20/2022 01:10 pm(Although we don’t know what they’re using… if it’s hydrolox like X-33, then they will struggle. It’s one of the worst SSTO propellants to use because of its low density.)I'd caveat that statement re: low density of hydrolox with "when used at normal mixture ratios in normal rocket engines". With LOX-rich TAN, you could theoretically make a stage O/F ratio of 12-18:1 work (instead of the traditional 4-6:1), which would help bulk density a ton, at the cost of lower Isp during the boost phase (which does help lower gravity losses though).I do agree though that pure LOX/LH2 at traditional mixture ratios has crappier bulk density than you'd want for an SSTO. When Aerojet did their TAN papers, they also looked at tri-propellant TAN -- where the main chamber was LOX/LH2, and the TAN injection was LOX/Kero. IIRC, they showed that that tripropellant approach actually closed way better than either pure LOX/Kero or pure LOX/LH2 for an SSTO designs -- high thrust and high bulk density for the start, high Isp for the end, and overall a great T/W ratio on the engines in booster mode (especially compared to typical LOX/LH2 engines).Given that Radian hasn't publicly stated what their engines are using, it's possible they could be doing something clever/unusual like this. Though I kind of think they would've said so if they were, because that would make the whole concept seem more plausible.~JonMaybe they were being guarded while TAN was going off-patent? The basic TAN patent is now open, but were the tripropellant modes free and clear then?
As john smith 19 pointed out before, this is quite similar to Boeing RASV, which also uses a sled for takeoff.Source: https://apps.dtic.mil/sti/citations/ADB216503
Would they win something if they combined it with a ramjet/scramjet engine - also on the way back? Also, why not make two variants, one unmanned cargo version and one manned. Starting with a manned version makes it more complicated and shaves off the margins.
Also, uncrewed launch is kind of a saturated market right now.Uncrewed launch with vehicles flying* or with hardware and within a couple years of launch:SpaceX (Falcon 9, Heavy, Starship)*Antares (NG)*ULA (Atlas, Delta, Vulcan)*Blue Origin (new Glenn)*ishRocketlab (electron, Neutron)*VirginOrbit*Astra*Firefly*ishABLRelativityand others (SLS? launcher?)That’s just in the US.Crewed orbital launch, currently flying:SpaceX. That’s it.In the future:Orion and Boeing are not far, but they’ll likely be too expensive for real commercial uses.Maybe Dream Chaser.So the list of orbital crewed launch is much smaller. And the revenue for crewed launch might be more than the whole smallsat launcher industry, so I don’t think it’s something to ignore.Enables satellite servicing and space tourism markets while also giving a possibility of those lucrative NASA crew contracts, which could be over a billion dollars per year (that’s like hundreds of micro/smallsat launches’ worth).
@JSThey may have other IP that is not mentioned in the patent, as when a patent is filed, they have 16 years to exercise it. So keeping it as a trade secret may be a better strategy depending on how long time they estimate it will take to develop. They have raised some money, so external parties have likely done some due diligence on the concept.
Did the shuttle have an escape pod?
If it's a plane, can they then forego the escape capsule as they can glide back to earth unpowered, unlike a rocket?
You assumed they got to 200 km/h with the sled? Would it not be possible to move that to 400 km/h and would that make any difference?
They are working on the marginals I believe and since they have raised that kind of money and attracted astronauts they must have found a way where the marginals are enough in their favor. If it was easy everyone would do it.
They are hiring...https://twitter.com/RadianSpace/status/1592915807138639875
I've been offline for some time but I did crunch some numbers for this. Aircraft don't really seem to have a "mass fraction" but they do have a "Fuel fraction" AFAIK the best of these ws for the Virgin Atlantic Global Flyer which Steve Fossett used to circumnavigate the world. It was built by Scaled Composites who also beat the previous 2 person aircraft to do this flight, Voyager. The GF had very low stress margins, a very low thrust to weight ratio and a cruise speed of about M0.5 (roughly 1/46 of orbital velocity at 200Km), so no transonic buffeting or drag rise to deal with. Not having to cope with re-entry heating helped the mass as well, as did no major concessions for repair/maintain/oper-ability. Basically a 1 flight and done aircraft.Voyager had a fuel fraction of 72%. With more than a decade more experience SC got the GF up to 86%.So arguably the best design/build team in the industry for one-off aircraft, lead by a designer who'd spent his lifetime acquiring (and using) the best techniques for composite construction available gets you a design that packs everything into 14% of GTOWLet's suppose however that between the sled launch and the wings aerodynamic lift all launch losses are cancelled. So all you need to work out the mission is to dial in the altitude, subtract sled speed at seperation, and that's the target delta V. So at 200Km that's 7785m/s. Assume the sled removes 200m/s that leaves 7585m/s. Using Dunns figure for Methalox of 368.3sec using a 20MPa (2900Psi) chamber pressure and 100:1 expansion ratio and run the rocket equation.This gives a structural fraction (for everything, vehicle, landing gear, all payload) of 12.25%That's 1.75% below the best ever achieved structural fraction for a winged vehicle. Rerunning the calculation with Dunns value for LH2 gives you 18.34%. And we haven't discussed the mass of the escape pod or the TPS yet. There really is Hydrogen and everything else. Boeing really did know what they were talking about when they designed RASV. The implication of this (which a freshman aeronautical engineering student should have been competent to do) are.a)That Radian have acquired (or developed) in total secrecy a structural architecture that makes much more efficient use of existing materials, or they have developed structural materials that are radically better than CFRP, or any other known materials*. Such a development would be a major breakthrough and would be valuable IP, and would truly be "disruptive."The patent makes no reference to any such material or technique. Of course they may be choosing to show off that aspect of the design with investors without making any public references to it, although I've never seen any other startups I'm aware of do this. orb) The design is total BS. I had always thought the X33 failed due to LM's over-promising undercooked technology and staffing the programme with b-team engineering talent to ensure failure. I had never considered the possibility that they also selected a project leader who belief in themself could have vastly outstripped their ability to execute. I'll need to update my ways-to-guarantee-project-failure list. Time will tell which one of these PoV's is accurate.*My Buzzword Bingo Generator (Materials Science Edition TM) came up with "Boron reinforced Magnesium Beryllium alloy"****Mg5Be was looked at in the Soviet Union in the 60's as a higher temperature cladding for Uranium metal fuel in CO2 cooled reactors. An upgrade from Magnox alloys.
1. Voyager mass ratio was 14%, but a lot of it is simply empty volume, as the pic below shows.
2. LOX is quite a bit denser than kerosene, especially supercooled. 1.25kgL is quite the difference from 1.14kg/L. Likewise, kerosene can be cooled to near-freezing (becomes a gel apparently). Depending on your kerosene mix, you could get 0.8kg/L at STP and maybe 2-4% density reduction?
3. Voyager took off under its own power, whereas this is a completely different beast. Most aircraft are limited by takeoff weight, and have volume to spare. See attached image of a KC-135 – the 110t of fuel simply goes where the luggage would on a normal airliner. The rest of the aircraft is just a big empty space.
Granted, pressure restraint, TPS, etc will add mass. But IMUEO <14% is achievable for a keralox lifting body. With a takeoff sled it can get to its maximum wing loading and take off. Whether it'll survive the usual weight gains is another story.EDIT: Wow my Engrish bad todayEDIT EDIT: So according to Wiki-not-a-real-source-pedia, cargo volume on the Beluga XL is 1500m^3, the airframe is 86.5t, so if you fill it with water (and it doesn't simply collapse) you get about a mass ratio of about 5.4%. Not that the wing loading, landing gear or internal structure can handle that. But the advantage of a flying wing with tanks is that the fuel in the tanks is directly at the point where the lift happens - no need for extra structure to carry the load.https://en.wikipedia.org/wiki/Airbus_Beluga
Yeah, the more I look at it, the more it looks like nonsense. You could skip the launch sled and drop from a Stratolaunch plane though you'd need to switch fuels and thus redesign the whole thing. But that's easy with vapourware.
As I did note it is possible that they have either developed (or acquired) a radically better material (or way of building a structure) that they have not publicised but are revealing to investors.
If they had either of those things, you would assume that there are better business models to reap the benefits of such an innovation, than making a launch company that is at best marginally w their initial offering and not even trying to dominate commercial launches Space X style or sell it to all the launch companies. The two latter would make more sense if their discovery is structural geometry or material.
But they could have some clever idea up their sleeve that they have not revealed - either because a patent is in the process or they want to keep it as a trade secret for as long as possible.
As they have hired some former astronauts that are also engineers, they should be able to discern if it's a viable idea, and there is also the due diligence from investors, who normally get 3rd party tech eval from some experts in the field. But the funds so far have been low, and it also depends on the professionalism of the investor.
The aerodynamics of such vehicles are also very complex. The accuracy of the models gets poorer as the speed rises, just where you don't need it. One (of the many) issues that doomed the NASP project as well.
I mean, even if it is mostly vaporware, good and functional aerogel TPS would probably make it all worth it anyway.
Apparently, testing of their aerogel TPS is progressing smoothly. https://www.linkedin.com/posts/radianaerospace_tps-hypersonic-activity-7171539686203543552-XXowApparently it's flexible? Or at least conformal. I'm slightly surprised they aren't utilising some of the metallic heat-shielding work that was done for x33 et. al.https://www.linkedin.com/posts/radianaerospace_aerogel-tps-activity-7155968228538687488-yc6Y
Quote The aerodynamics of such vehicles are also very complex. The accuracy of the models gets poorer as the speed rises, just where you don't need it. One (of the many) issues that doomed the NASP project as well.They have heard your concerns, John Smith, and have been doing work on that too:https://www.linkedin.com/posts/radianaerospace_the-radian-engineering-team-recently-collaborated-activity-7151254130429165568-VrZH
They posted some new renders to their website and a video
IIRC the entire dry mass (inc crew, ECLSS, structure and payload) has to fit in <12% to make kerolox work.
I get 12% with hydrolox, 8% with methalox and 7.6% with kerolox. This is final mass divided by total initial mass. However, when you look at final mass divided by propellant volume, I get 49 g/L with hydrolox, 73 g/L with methalox and 84 g/L with kerolox, which gives a substantial advantage to kerolox. Interestingly, keroxide (HTP/Kero) gets 81 g/L! A proper analysis needs to be performed for each propellant combination. A very good combination is O2/C7H8 (quadricyclene) that gets 8% and 95 g/L!
Not lot to be gained from Payload interview, better of reading Wiki or Eric Berger article.Eric said 200klbs engine and they will be partnering with another company on development. Usra has 200klb methalox engine in development so maybe them.
As others have said SSTO is big ask especially when starting from scratch. Something like Dawn's 2stage spaceplane would be better place to start from. The knowledge gained from operating such 2 stage vehicle would be invaluable if making leap to SSTO.
Quote from: TrevorMonty on 05/10/2024 12:51 amAs others have said SSTO is big ask especially when starting from scratch. Something like Dawn's 2stage spaceplane would be better place to start from. The knowledge gained from operating such 2 stage vehicle would be invaluable if making leap to SSTO.Only if you're first stage has the stretch to go to full orbital. I've heard this line floated before but I've never seen a TSTO evolve to an SSTO, and neither has anyone else.
Pointing to history only works if someone has actually made an attempt to do that thing before. Which, and please correct me if I am wrong, but in this case I'm 100% positive no one has.Put another way, I read what you just said as, "In all of human history, of the 0 attempts to evolve a TSTO into a SSTO, 0 have succeeded." Which is true, but doesn't mean much.
Radian was presenting on the FISO teleconhttps://fiso.spiritastro.net/telecon/Holder_7-10-24/Seems like a lot of work on thermal related stuff which might be of interest to others.Apparently there is a crossfeed from the sled to the spaceplane, and looks like a wet LOX wing tank setup as well.Nothing obvious about how the altitude compensation for the engines is achieved...
The question is... how much can cost this Radian One to development?
Quote from: TrevorMonty on 05/10/2024 12:51 amNot lot to be gained from Payload interview, better of reading Wiki or Eric Berger article.Eric said 200klbs engine and they will be partnering with another company on development. Usra has 200klb methalox engine in development so maybe them.True. Said their TPS is called "Durotherm," but not sure that get's us anywhere.Quote from: TrevorMonty on 05/10/2024 12:51 amAs others have said SSTO is big ask especially when starting from scratch. Something like Dawn's 2stage spaceplane would be better place to start from. The knowledge gained from operating such 2 stage vehicle would be invaluable if making leap to SSTO.Only if you're first stage has the stretch to go to full orbital. I've heard this line floated before but I've never seen a TSTO evolve to an SSTO, and neither has anyone else.
Easier to develop TSTO (suborbital spaceplace and expendable US) and they would have operational RLV that could make money while SSTO is being developed. The biggest difference between suborbital(TSTO) and orbital (SSTO) spaceplanes is thermal protection. Construction of vehicle, flight control SW, RCS, changing COG handling issues and engines would all be same.
Don't forget most difficult item with longest timeline, paperwork. Clearance to operate a large very fast autonomous drone from public airport. This is something thing Dawn has just been give permission after chipping away at it with authorities over years. Deploying something into orbit and reentry (satellite, US or SSTO RLV) is yet more paperwork.
Nothing obvious about how the altitude compensation for the engines is achieved...
I know they are both densified but it's possible the CH4 densifies harder, so it's density is actually greater than the LOX. AFAIK they are both basically linear, but I could be wrong.
The density of LOX varies from 2.7 (boiling points) to 2.88 (10 K above freezing point) times that of CH4. This could be due to the smaller range between the boiling and melting points of CH4 (21 K) and LOX (36 K).Density of LOX at 10 K above melting point of 54 K is 1.262 kg/L.Density of CH4 at 10 K above melting point of 91 K is 0.438 kg/L.Density of LOX at boiling point of 90 K is 1.14 kg/L.Density of CH4 at boiling point of 112 K is 0.423 kg/L.
Quote from: Steven Pietrobon on 07/23/2024 07:25 amThe density of LOX varies from 2.7 (boiling points) to 2.88 (10 K above freezing point) times that of CH4. This could be due to the smaller range between the boiling and melting points of CH4 (21 K) and LOX (36 K).Density of LOX at 10 K above melting point of 54 K is 1.262 kg/L.Density of CH4 at 10 K above melting point of 91 K is 0.438 kg/L.Density of LOX at boiling point of 90 K is 1.14 kg/L.Density of CH4 at boiling point of 112 K is 0.423 kg/L.Thanks for this Steven. That was the only thing I could think of that would put the LOX just in front of the engine and behind the fuel tank. The Cp/Cg mismatch has been known about for decades. It's part of the reason SS has a LOX tank in the nose. It's why Reaction moved their engines into nacelles at the wing tips. I don't see how Radian are going to make this work over roughly 23 mach numbers.
You nailed it. -It was already a giant PITA for Concorde, 60 years ago. And this was only fuel, and only Mach 2.
-It also plagued HOTOL four decades ago: it had the wing and the engine and the air intake all in the back, and thus severe CoG issues. They were so desperate they put not only canards in the front, but also the fin. Did not worked, they iterated again and again with no solution found: only the payload to orbit shrinking again and again, as if 7 metric tons was enough in the first place.
-As you noted, by 1989-1990 this led to the Skylon design (alas, Skylon traded that issue for another one: the engine noise impact on the rear fuselage - there was a NASA tech paper about it). -Note that REL's USAF TSTO has a different shape from Skylon, perhaps to try and solve the CoG issue: here we go again, iterating like HOTOL: damn.
-Heck even the Space Shuttle (with no hydrolox prop tanks whatsoever in the orbiter) had a lot of weight in the rear: the delta and the OMS pods and 3*SSMEs...
-Sometimes I wonder whether the X-37 shape is not the best - to balance all that weight in the rear. If only because it has the wings in the middle. Then again it has a V-tail so...
