Radian Crewed SSO Spaceplane

[Tywin]

They are hiring...

https://twitter.com/RadianSpace/status/1592915807138639875

[john smith 19]

They are hiring...

https://twitter.com/RadianSpace/status/1592915807138639875

Looks like this has closed.

[Lampyridae]

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 GTOW

Let'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.

or

b) 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 today

EDIT 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

[john smith 19]

1. Voyager mass ratio was 14%, but a lot of it is simply empty volume, as the pic below shows.

100-86=14
Fuel ratio is the term to look for when dealing with aircraft.

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?

True. The LOX tank on the Saturn stg2 and stg3 loooked tiny compared to the LH2 tanks, but where a very large fraction of the mass.

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.

Challenger was the Steve Fossett aircraft. Voyager was the previous generation. Both reached roughly 1/46 the peak speed that Radian needs to achieve.

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 today

EDIT 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

Mass ratio is all hardware (payload + structures)/GTOW
IMUEU?
Your right about the benefits of an LB, but AFAIK they are going wing+body. Their PM tried those with the X33. It didn't work out so well. 
A first generation spaceplane carrying a crew with 5 days on orbit?
That's a non-trival mass for ECLSS right there. Normal aircraft can process the atmosphere for cabin air, that's not an option for Radian.
The idea of a crew escape pod is also very mass heavy.
 I think the last that's tried it was the B1A, and that got dropped in development for ejector seats. The lightest you can get pushes everything except systems interfaces outside the pressure vessel. B1A was probably the last generation military aircraft with at least semi-mechanical controls, so quite a lot of machinery still inside the vessel
But time will tell. I've not aware of any updates on their website. It's pretty static. This is highly unusual for a US website for a launch vehicle company.
Len Cormier was the last great advocate of rocket based HTOL and he never thought SSTO was possible in this approach.

[Lampyridae]

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.

[john smith 19]

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.

Agreed.

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.

This is a highly unusual strategy (I've never heard of anyone using it) for raising support for a launch company.

But I wouldn't put money on it. 

[Halken]

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.

[john smith 19]

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.

I did note this.

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.

Correct.

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.

Well if you'd read the OP you'll notice the original investors really wanted to do a space lauch vehicle.

which basically means that actual due-dilligence went out the window. 

You need to develop better evaluation skills.

You see astronauts, engineers and investors

I see the guy who ran the X33 programme that cost the US taxpayer about $1.5Bn and delivered nothing (except the ability to claim SSTO is impossible and LM it's continued dominance of the USG launch market).

The limits of kerolox Isp are readily calculable and they bound the performance needed of any LV using them.

People have an inate desire to believe something is possible, and if it doesn't work now then "Something will turn up" as Mr Mcawber puts it.

 And this thing is possible with hydrolox. But not with kerolox. 

The problem is that the difference is huge 

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.

[jdon759]

Apparently, testing of their aerogel TPS is progressing smoothly.

https://www.linkedin.com/posts/radianaerospace_tps-hypersonic-activity-7171539686203543552-XXow

Apparently 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

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

[JEF_300]

I mean, even if it is mostly vaporware, good and functional aerogel TPS would probably make it all worth it anyway.

[john smith 19]

I mean, even if it is mostly vaporware, good and functional aerogel TPS would probably make it all worth it anyway.

True.

It's always nice to have another option for a reusable TPS, and the materials for the very highest performing ablative TPS's are difficult to get hold of.

BTW it turns out that both PICA and SIRCA ablative TPS's have a flexible option. 
SX have said this has greatly simplified accommodating hatches, windows and sensors, since you can just cut it, rather than machining a panel.

[john smith 19]

Apparently, testing of their aerogel TPS is progressing smoothly.

https://www.linkedin.com/posts/radianaerospace_tps-hypersonic-activity-7171539686203543552-XXow

Apparently 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

IIRC Rohr were the contractor for the metallic TPS. TPS is a key part of any RLV concept and if you can it's better to keep it in-house, or at least to have at least 2 contractors you can go to for it. 

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

LOL.   

Any vehicle that has to operate over roughly 23 Mach numbers is going to need very careful attention to its aerodynamics.
The if-it-looks-right-it-is-right school of aircraft design for this application is going to seriously wrong foot people. 

The joker in the pack is the Cp/Cg mismatch and how those numbers shift as the tanks empty and the speed moves over roughly 23 mach numbers Hint. If you're not going with VTO you don't need to put the engines at the back. You'd be better off putting them anywhere but the back.

I'm amazed they are still apparently in business but given the numbers for the Isp of a Kerolox engine I still can't see how they are going to make it

[lightleviathan]

They posted some new renders to their website and a video

[john smith 19]

They posted some new renders to their website and a video

With CGI anything is possible. 

IRL, with the lightest known aircraft structure at 16% of GTOW and the flat out Isp of Kerolox no.

IIRC the entire dry mass (inc crew, ECLSS, structure and payload) has to fit in <12% to make kerolox work.

Obviously they would make me look very stupid if they sent a sled down a runway tomorrow with a vehicle that made orbit on it, that actually made orbit. 

But I think I'm pretty safe.

Now if they were to switch to hydrolox....

[Steven Pietrobon]

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!

[john smith 19]

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!

Exactly. I can't see how they can pack that in the structures that can be built. Quadricyclene is impressive (it's cruise missile fuel IIRC) but it's not exactly cheap.  I think it was 10$/Kg? Has volume production pushed the price down?

Jess Sponable was right, you need to consider both tank and area masses. No one has built an aircraft ever with that low a dry weight. 

[TrevorMonty]

https://arstechnica.com/science/2022/01/radian-announces-plans-to-build-one-of-the-holy-grails-of-spaceflight/

https://en.m.wikipedia.org/wiki/Radian_Aerospace



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.

[john smith 19]

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.

True. Said their TPS is called "Durotherm," but not sure that get's us anywhere.

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.

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. 

[JEF_300]

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.

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.

[john smith 19]

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.

However there have been at least 2 attempts to develop transatlantic 2 stage mail planes. The British Mercury/Maia AKA Short Mayo Composite, being one.

The "Evolution" required is so radical (unless you have very high Isp engine, like SABRE) that's no one will build that much capacity into the baseline design.

What did happen was once Lindbergh proved non-stop transatlantic flight was possible (a decade before the Short Mayo) smart people moved on to growing the size of a vehicle that could make that crossing.

Once you dig into structural mass fractions of aircraft Vs rockets, and the order of magnitude difference between the best Isp (IE the 450s of the SSME) and the Isp of a poor air breather (about 3000s) your realise what a very long hill a pure rocket design would have to climb.