Author Topic: Externally heated SSTO launch vehicle  (Read 38003 times)

Offline Jim

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Re: Externally heated SSTO launch vehicle
« Reply #20 on: 01/18/2014 04:19 pm »

AFAIK, ABL intercepted during boost phase, not mid-course.


Where both the aircraft and target are mostly about the atmosphere (ABL at 40k ft and target likely higher)

Offline darkbluenine

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Re: Externally heated SSTO launch vehicle
« Reply #21 on: 01/18/2014 05:48 pm »
What metal?  The casings are composite.

ABL's target wasn't U.S. ICBMs.  Today, several active Soviet/Russian ICBM designs do not use composite casings (or even solid motors).  More so back when ABL was designed.

Where both the aircraft and target are mostly about the atmosphere (ABL at 40k ft and target likely higher)

About 20% of the atmosphere is left at 40k ft.  ABL's goal was a 600km range.  It's classified whether they reached that range in testing.  But if they did, 500-600km of 20% of our atmosphere is a decent proxy for getting a laser up through 100-200km of our standard atmosphere, especially given that ABL had to put more energy into a smaller area than what Kare's concept requires.

Offline KelvinZero

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Re: Externally heated SSTO launch vehicle
« Reply #22 on: 01/18/2014 11:01 pm »
This thread started discussing a skylon sized vehicle.

A less exciting but much more plausible first application would be a very small payload, launched frequently, with very high g-forces. These factors all allow you to build a much smaller installation on the ground and use it continually, rather than something many times larger used for only a few minutes every year.

Something like that could be used to deliver propellant to a propellant depot in LEO. If it proves it self at this level then we would have the experience to think bigger.

Offline Asteroza

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Re: Externally heated SSTO launch vehicle
« Reply #23 on: 01/20/2014 01:06 am »

That said, I'm unaware that anyone has tested a heat exchanger for either Kare's or Parkins' approach, and until their claimed efficiencies are validated, there's no reason to go further with either concept.  But unlike Parkins' approach, Kare's could easily leverage any number of military lasers for this test -- I'm sure they'd appreciate having the target to shoot at.

Parkin's http://thesis.library.caltech.edu/2405/1/Parkin-Thesis.pdf thesis includes microwave heated heat exchanger testing of a subscale single tube heat exchanger, though it was using resonant cavity effects which may be harder to pull off in a full heat exchanger with different beam angles. Allegedly he was able to swing Kare around to considering SiC heat exchangers, when Kare had originally sworn them off.

Offline john smith 19

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Re: Externally heated SSTO launch vehicle
« Reply #24 on: 01/23/2014 09:21 pm »
It's also worth mentioning that the job of incoherently combining multiple beams on a heat exchanger to vaporize LH2 is actually much easier than the ABL's job of coherently focusing one large beam on a solid rocket casing long enough to punch through the metal.
True. If anything you'd want the beam to spread over the HX (std abbreviation) evenly.
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I like Kare's approach a lot.  It transfers much of the complexity of a launch vehicle to the ground, it's highly scalable, and it leverages Moore's Law-like trends in semiconductor lasers.  It's the lazy man's (read "easiest") approach to power beaming and laser launch.  The precision required of Myrabo's Lightcraft and the fact that the thinning atmosphere at higher altitudes worked against it always seemed like snake oil to me.  And the inability to test a microwave launcher without installing a huge microwave array first makes Parkins' approach seem like a non-starter.
Huge? Magnetrons run into the 100Kw-1MW range. The minimum spot size of a 3cm radar beam is not that serious an issue given the size of the target. They also tend to have high efficiency, 90%+ (IIRC).
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That said, I'm unaware that anyone has tested a heat exchanger for either Kare's or Parkins' approach, and until their claimed efficiencies are validated, there's no reason to go further with either concept.  But unlike Parkins' approach, Kare's could easily leverage any number of military lasers for this test -- I'm sure they'd appreciate having the target to shoot at.
I think building what is a CW radar transmitter is likely to be easier than persuading the military to runs such tests.  :(
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If Kare's heat exchanger was validated, sub-scale, 1-10kg payload testing would make sense.  But proceeding to the full-scale, $2-3B array for 100kg payloads couldn't be justified unless there was a huge market, like unitized propellant (re)supply or massive swarmsat array deployment/replenishment.
True. This is a big issue with this system. The up front costs are huge for a one shot payload which is tiny (comparatively speaking). There is also the issue that the architecture pretty much restricts you to a single direction from the launch site.

Getting that HX design validated would be a big step toward moving the concept along.  :(

Since Skylon has been mentioned I'll note REL estimate a $1Bn cost for a vehicle but a 150 payloads to give the equivalent of 1 Skylon flight, with roughly a $15m flight cost averaged over 200 flights.
« Last Edit: 01/23/2014 09:36 pm by john smith 19 »
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline darkbluenine

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Re: Externally heated SSTO launch vehicle
« Reply #25 on: 01/23/2014 10:02 pm »
Huge? Magnetrons run into the 100Kw-1MW range. The minimum spot size of a 3cm radar beam is not that serious an issue given the size of the target. They also tend to have high efficiency, 90%+ (IIRC).

Sorry, I should have been more clear.

For Kare's approach to start scaling up, we have to demonstrate the HX and one of his lasing units.

For Parkin's approach to start scaling up, we have to demonstrate the HX and phase locking of multiple big gyrotrons feeding a phase controlled mm array.

Maybe I'm wrong, but my gut tells me that all that phase locking and phase controlling over multiple gyrotrons and antennas is going to be harder than demonstrating one lasing unit.  I'm lazy -- I'd take the approach where I just have to point beams in the right direction over the approach where I have to phase lock/control beams on top of pointing them in the right direction.   I think Table 2 in the joint Kare/Parkin paper, which shows that the microwave approach is at a lower TRL (2-3) than the laser approach (3-4), justifies my gut.  (But I'll admit that the table is close.)

If I was a manager running a program in this area, I'd run with Kare's approach as the leader but throw enough resources at Parkin's approach to keep it in a follower position in the event that Kare's approach falters.

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...easier than persuading the military to runs such tests.  :(

My experience is limited to a couple phone discussions a couple years ago, but I got the opposite reactions when bringing this up.

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Getting that HX design validated would be a big step toward moving the concept along.  :(

Agreed.  WAG is probably less than a million or two to get it done.  Would be great to see DARPA or someone fund it.

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Since Skylon

I profess to not understanding how Skylon will work technically or programmatically, but that doesn't mean that it won't.


Offline Asteroza

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Re: Externally heated SSTO launch vehicle
« Reply #26 on: 01/23/2014 10:49 pm »
I should probably point out Kare is advising Lasermotive, a company which previously participated in the space elevator climber competition, beaming power to a tether climber, and is currently marketing UAV and remote sensor power beaming technologies (and slightly more near-term stationary tethered UAV work where the tether is a fiber optic cable feeding both power up and data down). So, if anyone is progressing the related technologies in the white-world commercial sense, it probably is Lasermotive.

http://lasermotive.com/news/blog/

Offline john smith 19

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Re: Externally heated SSTO launch vehicle
« Reply #27 on: 01/24/2014 08:58 am »
Maybe I'm wrong, but my gut tells me that all that phase locking and phase controlling over multiple gyrotrons and antennas is going to be harder than demonstrating one lasing unit.  I'm lazy -- I'd take the approach where I just have to point beams in the right direction over the approach where I have to phase lock/control beams on top of pointing them in the right direction.   I think Table 2 in the joint Kare/Parkin paper, which shows that the microwave approach is at a lower TRL (2-3) than the laser approach (3-4), justifies my gut.  (But I'll admit that the table is close.)
This is the technology of satellite solar power. I'm not sure about Gyrotrons but it was solved for magnetrons in the late 1970's.
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If I was a manager running a program in this area, I'd run with Kare's approach as the leader but throw enough resources at Parkin's approach to keep it in a follower position in the event that Kare's approach falters.
I'd guess the Gyrotrons are about 4x the electrical efficiency of the laser system. When you're talking a few watts from a wall socket that's not really an issue. But these systems are big. Note that 10MW gas turbines are feasible in 2 20" containers as well. 
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My experience is limited to a couple phone discussions a couple years ago, but I got the opposite reactions when bringing this up.
Now that does surprise me.
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Agreed.  WAG is probably less than a million or two to get it done.  Would be great to see DARPA or someone fund it.
There is sort of some work in this area.  :(
In 2003/4 there was a thesis written describing work on embedded heat pipes in Alumina substrates. I'm not talking about thin metal pipes, I mean out of the Alumina itself. This was in respect of cooling electronic components on hybrid devices. The basic work used water with slots of different widths to define edges the water would travel in due to surface tension. It was rated at 30w/cm^2, which is not bad given the Apollo heat shied was rated at 100w/cm^2.

Hybrid substrates are processed in rolls up to 4 feet wide. Individual substrates are up to 4 sq inches.



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Since Skylon

I profess to not understanding how Skylon will work technically or programmatically, but that doesn't mean that it won't.
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline RanulfC

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Re: Externally heated SSTO launch vehicle
« Reply #28 on: 01/24/2014 04:14 pm »
Maybe I'm wrong, but my gut tells me that all that phase locking and phase controlling over multiple gyrotrons and antennas is going to be harder than demonstrating one lasing unit.  I'm lazy -- I'd take the approach where I just have to point beams in the right direction over the approach where I have to phase lock/control beams on top of pointing them in the right direction.   I think Table 2 in the joint Kare/Parkin paper, which shows that the microwave approach is at a lower TRL (2-3) than the laser approach (3-4), justifies my gut.  (But I'll admit that the table is close.)
This is the technology of satellite solar power. I'm not sure about Gyrotrons but it was solved for magnetrons in the late 1970's.

It's also very close to "phased-array" and phase-locked-array radar systems. Lower "TRL" than actually making a "pointed" beam but then again we've been playing with MASERs for decades :)

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If I was a manager running a program in this area, I'd run with Kare's approach as the leader but throw enough resources at Parkin's approach to keep it in a follower position in the event that Kare's approach falters.
I'd guess the Gyrotrons are about 4x the electrical efficiency of the laser system. When you're talking a few watts from a wall socket that's not really an issue. But these systems are big. Note that 10MW gas turbines are feasible in 2 20" containers as well. 

I'd actually put some more money into the Parkin concept just to get it up to current "Laser" research standards.
Then again I want to put a lot of money in to a lot of different areas :)

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My experience is limited to a couple phone discussions a couple years ago, but I got the opposite reactions when bringing this up.
Now that does surprise me.

Shouldn't really :) One of the issues with military test programs is that they tend to face on-again/off-again funding and interest levels. Any use generates some data and that's a good thing and a lot better than having to close everything up :)

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Agreed.  WAG is probably less than a million or two to get it done.  Would be great to see DARPA or someone fund it.
There is sort of some work in this area.  :(
In 2003/4 there was a thesis written describing work on embedded heat pipes in Alumina substrates. I'm not talking about thin metal pipes, I mean out of the Alumina itself. This was in respect of cooling electronic components on hybrid devices. The basic work used water with slots of different widths to define edges the water would travel in due to surface tension. It was rated at 30w/cm^2, which is not bad given the Apollo heat shied was rated at 100w/cm^2.

Hybrid substrates are processed in rolls up to 4 feet wide. Individual substrates are up to 4 sq inches.

Great where can I get some to start with? :)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline john smith 19

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Re: Externally heated SSTO launch vehicle
« Reply #29 on: 01/24/2014 06:33 pm »
It's also very close to "phased-array" and phase-locked-array radar systems. Lower "TRL" than actually making a "pointed" beam but then again we've been playing with MASERs for decades :)
Very. In fact IIRC the Safeguard ABM radars were all phased array and in the MW range back in the early 70's.
MASERS never really caught on except AFAIK in very low level signal amplification tasks. You just don't seem to see industrial cutting MASERs in the way that LASERs are (relatively) common place.
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Shouldn't really :) One of the issues with military test programs is that they tend to face on-again/off-again funding and interest levels. Any use generates some data and that's a good thing and a lot better than having to close everything up :)
I never really thought of that.  :)
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Great where can I get some to start with? :)
You'll need to contact your local hybrid substrate supplier. They are like a cross between a PCB mfg house and a biscuit factory.  :)

The heat pipe is realized by grooves in the cofired substrate, usually of 2 different widths. Each layer can be down to 2 thou thick and the substrate stack can be up to 0.2" thick.

Filling will be tricky.

And I can reference the thesis for once.  :)

It's from Florida International University 2001 DPhil Engineering Mark Zampino "Embedded heat pipes in cofired ceramic substrate for enhanced thermal management of electronics".
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline RanulfC

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Re: Externally heated SSTO launch vehicle
« Reply #30 on: 01/24/2014 07:07 pm »
It's also very close to "phased-array" and phase-locked-array radar systems. Lower "TRL" than actually making a "pointed" beam but then again we've been playing with MASERs for decades :)
Very. In fact IIRC the Safeguard ABM radars were all phased array and in the MW range back in the early 70's.
MASERS never really caught on except AFAIK in very low level signal amplification tasks. You just don't seem to see industrial cutting MASERs in the way that LASERs are (relatively) common place.

I blame Laser's better PR department myself...

And thanks for the refernce :)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline john smith 19

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Re: Externally heated SSTO launch vehicle
« Reply #31 on: 01/25/2014 11:58 pm »
Very. In fact IIRC the Safeguard ABM radars were all phased array and in the MW range back in the early 70's.
MASERS never really caught on except AFAIK in very low level signal amplification tasks. You just don't seem to see industrial cutting MASERs in the way that LASERs are (relatively) common place.

I blame Laser's better PR department myself...

And thanks for the refernce :)
You're welcome. It's a nice change to actually find a pdf I mention on my PC.  :) BTW Safeguard also used one of its radars to control the Sprint interceptors, as (AFAIK) they did not have an actual on board computer.  This meant punching through the plasma sheath with just raw signal power.

So I'd say focusing those MW signal outputs onto a pretty small object (roughly a 30'x < 6' cone) is viable.
[edit I think that makes it the worlds most deadly RPV  by quite a wide margin]
« Last Edit: 01/26/2014 11:15 am by john smith 19 »
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline Asteroza

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Re: Externally heated SSTO launch vehicle
« Reply #32 on: 01/27/2014 12:49 am »
Also for reference, MASER's weren't popular due to resource and cost issues but recent research results are allegedly breathing new life into the maser research space.

Organic crystal solid state room temperature maser

http://www.nature.com/nature/journal/v488/n7411/full/nature11339.html

Offline kkattula

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Re: Externally heated SSTO launch vehicle
« Reply #33 on: 01/27/2014 01:42 am »
They're cool concepts, with lots of interesting discussion on lasers, heat exchangers, etc.

What's been glossed over is that for these concepts to work, they require very big & very light LH2 tanks. Most of these papers specifically don't get into 'vehicle design', just make general assumptions. Where they do specify tank mass ratios, they look aggressive, but plausible.

Until you apply those same tank masses to vehicles using conventional rocket engines and high density propellants. We're talking much better than SSTO with LOX/RP1. If you can do that, why bother with lasers, etc?


Much like STP and NTP, it has potential as an in space propulsion technology, where thrust (and hence heat exchanger mass) can be kept very low. Where also initial mass is expensive, so high Isp is valuable.
« Last Edit: 01/27/2014 01:43 am by kkattula »

Offline Solman

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Re: Externally heated SSTO launch vehicle
« Reply #34 on: 01/28/2014 10:03 pm »
They're cool concepts, with lots of interesting discussion on lasers, heat exchangers, etc.

What's been glossed over is that for these concepts to work, they require very big & very light LH2 tanks. Most of these papers specifically don't get into 'vehicle design', just make general assumptions. Where they do specify tank mass ratios, they look aggressive, but plausible.

Until you apply those same tank masses to vehicles using conventional rocket engines and high density propellants. We're talking much better than SSTO with LOX/RP1. If you can do that, why bother with lasers, etc?


Much like STP and NTP, it has potential as an in space propulsion technology, where thrust (and hence heat exchanger mass) can be kept very low. Where also initial mass is expensive, so high Isp is valuable.

Kare suggests ammonia or methane as alternate propellants. Depending of course on how high the temperature the heat exchanger can operate at, these propellants can have Isp 's much higher than LOX/RP1 when externally heated. At the cost of greater complexity, Kare also proposes nitrogen injection into the heated hydrogen exhaust.
I wonder if it might be advantageous as well to consider altering the flight profile to remain in the atmosphere longer and use ram compressed air for a significant portion of the trajectory.
Another possibility might be external heating using a waverider type vehicle. I imagine this could work by injection of carbon soot into the shock wave beneath the vehicle to absorb incident laser or microwave  energy. The underside could perhaps be made reflective to further concentrate the energy into the most desirable region. As the wave is heated it will expand and perhaps accelerate the waverider vehicle. This would have the advantage of being able to use air as the primary propellant along with some soot of course. Waveriders have the potential to handle the excessive temperatures created by air friction if I understand correctly and unlike chemically fueled scramjets, the beam can in theory add enough energy to accelerate the vehicle even at Mach 25 or more. I realize that's rather speculative but such a vehicle could have a high payload mass fraction and still be constructed robustly enough to be reusable since it would carry only the soot instead of all of its propellant.
As far as in space use goes, I disagree that beam powered propulsion should be a low thrust proposition since its chief advantage over STP and NTP is that the beam can deliver far more energy per unit vehicle mass than either of these alternatives. With beam powered propulsion you can have both high Isp AND high thrust making transit time between Earth and Mars extremely short. There are pulsed laser propulsion concepts that have Isp's over 5000 sec IIRC and beam powered electric propulsion using PV designed for the particular laser wavelength of the beam could reach Isp's way beyond even that.
In addition BPP for launch to LEO can involve small vehicles launched very frequently - dozens of times per day perhaps - which has a dramatic effect on cost per launch. Vehicle turnaround would presumably be quite fast and straightforward given the inherent simplicity of a BPP vehicle vs. a chemical rocket.
It achieves high launch rate cost efficiency by its very nature.
Compared to the competition BPP seems almost like cheating to me.

Offline mmeijeri

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Re: Externally heated SSTO launch vehicle
« Reply #35 on: 01/29/2014 12:55 am »
Both. the viability of a beamed vehicle making it to orbit is questionable.

How about a beamed first stage rather than an SSTO, and using ammonia rather than hydrogen? Not necessarily in the short term, but do you think such a thing is plausible eventually?
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Offline grondilu

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Re: Externally heated SSTO launch vehicle
« Reply #36 on: 01/29/2014 07:21 am »
I was thinking about something like that the other day.  More precisely, I was thinking about focusing solar energy with computer-controlled mirrors on the ground, in order to heat water inside a rocket.

But then it occurred to me that if the rocket must contain water, we might as well use it to store energy.  And this can be done quite efficiently by storing water in its separate constituents, namely oxygen and hydrogen.  That's basically what conventional rockets do, and those rockets already reach temperatures that are as high as current material science can withstand for designing nozzles.   So using an external source of energy will probably not be much useful, since it won't allow for higher temperatures.

So, I don't think it makes much sense, unless we're talking about using engines that can withstand much higher exhaust temperatures than what can be achieved with chemical energy.
« Last Edit: 01/29/2014 07:37 am by grondilu »

Offline mmeijeri

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Re: Externally heated SSTO launch vehicle
« Reply #37 on: 01/29/2014 11:21 am »
The point with externally heated propulsion, and also with nuclear propulsion, isn't so much higher temperatures, but lower molecular weight of the exhaust gases. Hydrogen is the best option here, but unfortunately it has very low density. Ammonia comes second and is much denser. It's also storable, which is nice but not crucial for launch vehicles. Hydrazine is another option, but it's not very desirable for launch vehicles.
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Offline RanulfC

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Re: Externally heated SSTO launch vehicle
« Reply #38 on: 01/29/2014 01:50 pm »
The point with externally heated propulsion, and also with nuclear propulsion, isn't so much higher temperatures, but lower molecular weight of the exhaust gases. Hydrogen is the best option here, but unfortunately it has very low density. Ammonia comes second and is much denser. It's also storable, which is nice but not crucial for launch vehicles. Hydrazine is another option, but it's not very desirable for launch vehicles.

Actually the point of Beamed propulsin (along with NTR) IS higher temperature, up to the materials limit of the absober/HX. You get a much higher exhaust speed with lighter propellants but you CAN use just about anything. The most salient points are that you only require one "propellant" (usually with a much higher ISP than "normal" mono-propellants) and associated handling and storage and since the majority of your "power generation" capability is left on the ground you end up with a much higher thrust and efficiency than you would having to carry it all in the vehicle.

I'll make a short note that the idea of using LN2 was to add exhaust mass for higher thrust at the begining of the flight trajectory. Ammonia is a good choice as well, especially for early use. Water would be "good" but you have to get it hot enough that you have disassociation, and then recombination in the exhaust nozzle area. Tricky.

As to "air-breathing" it could work though I'd think that the complexity and heating issues of hypersonic flight would be major issues and probably not worth the effort with beamed power.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline mmeijeri

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Re: Externally heated SSTO launch vehicle
« Reply #39 on: 01/29/2014 02:48 pm »
Actually the point of Beamed propulsin (along with NTR) IS higher temperature, up to the materials limit of the absober/HX. You get a much higher exhaust speed with lighter propellants but you CAN use just about anything.

Solid core NTRs don't have higher temperatures than chemical rockets, the gains come from lower molecular weight. I don't think its any different for beamed propulsion. Do you have any numbers that contradict this?
Pro-tip: you don't have to be a jerk if someone doesn't agree with your theories

 

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