Discussion A REAL Delta Glider (well, almost)

[jedidia]

Well, realistic kind of brings specialized with it. We simply don't have the tech for a universal vehicle, won't have it for a loooong time, and it's doubtfull we'll ever have it.

 

[T.Neo]

Axel, you don't get it. This isn't an extraterrestrial lander, and it never will be. Because that capability cannot be placed within this design, and even if it were, it would result in a problematic vehicle.

Today we would need 4 vessels: 1. HLV 2.support shuttle(your DG) 3.interplanetary transfer vessel 4.Lander
That makes missions very complex and expensive.

Look at it this way; I'm not making a shuttle as an integral part of a Mars program. I'm making a shuttle as a shuttle, that can transport 6 people and a bit of cargo to LEO.

Now when a Mars mission comes around, it is not a hindrance, an extra, costly vehicle that has to be supported. It is instead an asset, already existing infrastructure, that can be exploited for a relatively low cost.

Now on the other hand, when I pack every other thing into the spacecraft, like such nonsense as hover engines and their doors, and suchlike, then it becomes horribly impractical as an LEO shuttle... because it doesn't need any of those things, they just become parasitic mass/cost/failure points.

And when the Mars mission comes around, it's does a bad job as a lander anyway. It makes no sense at all.

Pure support shuttles we have enough at orbithangar, which are allready realistic.

Uh... no. No offence to any addon developers, but I don't think there's been anything of the sort of a "realistic DG" released on OH. If there has been, I haven't seen it.

Parasitic mass is parasitic mass. I don't care how fancy the transfer craft is, you're wasting kilograms that could otherwise be dedicated to useful mission equipment. Or people, or their food, or their air, or their safety measures, etc.

I pushed a Resolve-Shuttle (with 120mT own fuel inside) easy to mars by VASIMR.

Which VASIMR? One based off of real-world design studies?

With your DG the crew could return to earth instantly.

Actually they could... all that needs to be done, is the interplanetary spacecraft, pulling up alongside an orbiting shuttle/station with shuttle docked, and they can get down to Earth relatively quickly.

It is not problematic.

If you not implement the Hover i will do itself in every case, like i did it for the DGEX and Starclipper.

If you want make your own hover-equipped spacecraft, go ahead.

I'd love to see STS with hover engines. :facepalm:

You sayed that Skylon is big and slow, but now yours is mutch bigger!

I never said that Skylon was "slow", I was referring to the large mass ratio that Skylon has to endure.

I actually end up having a similar mass ratio, but I have less relative volume dedicated to propellant (due to denser propellant).

I would not call mine much bigger. Indeed, I already have 4 ton payload, 1.5 tons of other consumables, and a good deal of fuel for the RCS/OMS; the actual dry mass of the vehicle, would probably be comparable to Skylon.

Despite having engines with heavy radiation shielding.

I can to some calculations, this could remove the HLV from mission profil .

Where is there an HLV in the mission profile?

This is not an HLV, it is a light shuttle.

To fix the engine problem at emergency abort, you can set one engine above the other

I can't do that. My fuel tanks are set up as radiation shields for the engines, putting them one above the other would mess up the airframe a good deal.

But i guees, all my ideas will be wrong for you again

Unfortunately, I have to say yes. But that is not because I am trying to be mean, I am trying to make a very calculated design process here, and I am doing things for a reason.

Well, realistic kind of brings specialized with it. We simply don't have the tech for a universal vehicle, won't have it for a loooong time, and it's doubtfull we'll ever have it.

Well, if you have a VTOVL, almost like a sort of nuclear DC-X, then maybe you can talk about turning it into a vehicle for landing on planets such as the Moon or Mars, because it would be more suited to it.

Of course, you would still have the annoying parasitic mass. That might even mean such vehicles operating in environments such as the Moon would have their TPS, etc, ripped off to save mass...

Other vehicles aren't so easy to universalise. You can't fly to Mars in a 5-seater spaceplane, but then again, you can't cross the atlantic in an inflatable dinghy. So the inability to specialise there is not limited to spaceflight.

Is 50-60 tons dry mass really too much for such a vehicle? Could it be whittled away a bit more, considering that it's supposedly supposed to be a small vehicle in the first place?

Did my iterative process encounter a strategic failure?

 

[Hielor]

To fix the engine problem at emergency abort, you can set one engine above the other:thumbup:
You would not need any engine tilting or any massiv rudder surface attacks.

That would result in change in the pitching moment, which would still require engine tilting or a change in elevator trim.

Every pilot (in America, at least) who earns a multi-engine rating is trained to deal with the new yaw forces associated with an engine failure. This isn't surprising or unexpected; it's part of the training. Presumably the pilot's of TNeo's spaceplane will be decently well trained, so there shouldn't be any problem with having side-by-side engines.

 

[Axel]

@T.Neo
You speak about a better mass ratio? But 5,5 tonnes payload transported by 400 tonnes fuel and 70 tonnes empty mass, sounds not very efficient, thats 1% only! You decalculated it. It has at Isp 8800m/s a dV of 16.715km/s that offers really BIG payloads!!!

Skylon reaches 4,6% and our best real vessel in past, was Saturn5 with 4% too! This was pure chemical, particulary with lower efficient kerosine/LOX only!

Skylon has a mutch better mixed Isp of around 20 000m/s, because its airbreath mode at the beginning. A nuclear thermal engines has overall Isp of 8800-10 000m/s. But better 8800m/s, for a longer lifetime. The temperature in core is at 10 000m/s around 1000°C higher!

List of shuttles which could be real:
-Tx5
-Starclipper68
-Titov and Orion3 (Wo2k1)
-XR2 and XR5 (right and real configured)
-DeltaGliderEX (the old one without plasma engine)
-Starliner G40 (under developing)
-Skylon
-Resolve (configured to NTR values, an STTO)

and alot more, but not my favorites

That all i rode at this thread is to contradiction for me. So build this vessel and we will see and you will see! God luck :thumbup:.

The VASIMR vessel i use for interplanetary travel is this

[ame="http://www.orbithangar.com/searchid.php?ID=3212"]USS Bekuo VASIMR v.1.01[/ame]

USS Bekuo is a real advanced plasma propelled spacecraft project, developed by Dr.Franklin Chang-Diaz and his team in Advanced Space Propulsion Laboratory at the Johnson Space Center. Now work continues in AdAstra Rocket company.

Its very nice and nuclear :lol:. Skylon is although a nuclear shuttle, if we get the LOX/H2 by water electrolyzes by a nuclear power plant :thumbup:


@Hielor
Vertical engine tilting and elevator trim is mutch easier! And its for orbinauts, most are not high trained profis.

T.Neo speaks about radiation, i thought its soooo veeeeery safe, so dont worry. If not, its a contradiction for me. You protects astronauts in cockpit then, but not the area upper side/down side the engines? It contaminates runways and air. If you say there are extra shields for that sides, you could never fly it by near empty tanks, to keep working the fuel shielding.

 

[T.Neo]

You speak about a better mass ratio? But 5,5 tonnes payload transported by 400 tonnes fuel and 70 tonnes empty mass, sounds not very efficient, thats 1% only! You decalculated it. It has at Isp 8800m/s a dV of 16.715km/s that offers really BIG payloads!!!

Your figures are incorrect. My exhaust vel is 7198.6 m/s, and my main engine propellant is 333.63 tons. That, at a mass ratio of 4.766, means a dV of 11 240 m/s.

I am using methane propellant, so I can have smaller propellant tanks. Which unfortunately degrades my exhaust velocity.

List of shuttles which could be real:

Please read what I said;

Uh... no. No offence to any addon developers, but I don't think there's been anything of the sort of a "realistic DG" released on OH. If there has been, I haven't seen it.

Yes, they are surface to orbit shuttles, but they're not similar to this particular concept.

-XR2 and XR5 (right and real configured)

I have already covered this previously:

Yes the XR1 is mostly a tank, and the shuttle is mostly a payload bay, but it ends up being quite similar... the volume taken up by payload bay and propellant tank is probably proportionally similar; indeed, the crew section is proportionally much larger than that of STS.

Also, do not accuse me of guessing. After modelling an internal fuel tank, to fit in the DG and presumably accomodate the other internals (engines, SCRAMs, hovers... wait... why are there hover engines in a spaceplane?), and doing a density calculation, it turns out you can only carry 3.86 metric tons of LH2, and around 4.2 tons of slush H2.

So yeah... ain't gonna work. Unless you use a flux generator to compress it into neutron star material.

Just because you enter "realistic" values, does not mean the vessel is realistic. Especially when it would have to be three times the size, to carry that amount of fuel.

-DeltaGliderEX (the old one without plasma engine)

I don't think so. I may be incorrect, but I think the engine ISP is pretty much similar to that of the DG...

And the vehicle is something like half the density of STS...

-Starliner G40 (under developing)

Probably your best bet, but even then, the engines have a fictional configuration (RAMCASTER; as far as I know, they do not break physics in any way, but they're not strictly based on the operating principles and parameters of any real world design or study).

Please correct me if I am wrong, but I'm not sure if Moach has done any in-depth engineering or physics numbers behind the vehicle.

-Resolve (configured to NTR values, an STTO)

Again, just because you input "realistic" values, doesn't make the vehicle realistic.

That all i rode at this thread is to contradiction for me. So build this vessel and we will see and you will see! God luck .

Could you please clarify?

The VASIMR vessel i use for interplanetary travel is this

Ah ok, sounds like a good addon.

Vertical engine tilting and elevator trim is mutch easier! And its for orbinauts, most are not high trained profis.

I don't think I'll be implementing random engine failures, however...

T.Neo speaks about radiation, i thought its soooo veeeeery safe, so dont worry. If not, its a contradiction for me. You protects astronauts in cockpit then, but not the area upper side/down side the engines? It contaminates runways and air. If you say there are extra shields for that sides, you could never fly it by near empty tanks, to keep working the fuel shielding.

It is soooo veeeery safe, because the fuel tanks are in the way. I have other shielding, the fuel just makes it even safer.

There is side shielding, of course it does not offer the same amount of protection as the propellant tanks when full, but people are not going to be that close to the craft when it takes off... STS, for example, has a more than 4 kilometer exclusion zone anyway.

 

[Axel]

I don't think so. I may be incorrect, but I think the engine ISP is pretty much similar to that of the DG...
And the vehicle is something like half the density of STS...

The DGEX is two times the shuttle in size and weight = same density.
And it has a large empty payload bay too!
But time has come for better, mutch lighter materials, like composites/carbon.
Ok, its internal "space engine" when it switchrs at 65km altitude, is a little bit unrealistic, but without this it could reach LEO, like the other concepts, as an airbreathing shuttle, when its uses a rocketmode for the rest of the way to LEO.

Especially when it would have to be three times the size, to carry that amount of fuel.

The XR5 can hold 415mT fuel, LOX and H2, ok LOX mass is abut 80% of it.
But its engine consumes this mix in rocket mode. If you think this mass is to big too, then we can use a part of the payload bay. Put an STS ET near the XR5, you will see how small it is, and it holds 720mT fuel! And dont forget, the real space shuttle has internal real 20mT fuel for OMS !!! Where does it hide this, the space for it seems to be very small too?! Its because fuels doesnt need that huge tank volume you alltime think.

Your figures are incorrect. My exhaust vel is 7198.6 m/s, and my main engine propellant is 333.63 tons. That, at a mass ratio of 4.766, means a dV of 11 240 m/s.

You will see that it can lift mutch more than 5,5 tonnes payload!

I don't think I'll be implementing random engine failures, however...

Its an simulation and some people could imagine "what when it happens"
Ofcoures the Space shuttle explodes although never in orbiter, but i love other shuttles more because they would be more safe in reality.

Again, just because you input "realistic" values, doesn't make the vehicle realistic.

Same to your project, as long orbiter doesnt simulate structurally limits and other things, we have only these values and our experience.

The VASIMR vessel i use for interplanetary travel is this

Ah ok, sounds like a good addon.

NICE you are at my opinion, so i close discusion for next time :lol:

 

[T.Neo]

The DGEX is two times the shuttle in size and weight = same density.
And it has a large empty payload bay too!
But time has come for better, mutch lighter materials, like composites/carbon.

The Shuttle has a payload bay as well. That doesn't make it half as dense as it really is.

There's a difference between composites, and unobtanium...

Ok, its internal "space engine" when it switchrs at 65km altitude, is a little bit unrealistic, but without this it could reach LEO, like the other concepts, as an airbreathing shuttle, when its uses a rocketmode for the rest of the way to LEO.

"It's unrealistic" is exactly what I'm saying about the engine.

Airbreathing shuttle? I am not so sure...

The XR5 can hold 415mT fuel, LOX and H2, ok LOX mass is abut 80% of it.
But its engine consumes this mix in rocket mode. If you think this mass is to big too, then we can use a part of the payload bay. Put an STS ET near the XR5, you will see how small it is, and it holds 720mT fuel!

Except, we can't use part of the payload bay. Because that is almost as bad as having an invisible external drop tank on a DG. And it doesn't make it any more realistic; the fact that most of the nose is crew/passenger section, and the rear is engines, means you cannot have much volume for fuel.

And realistic doesn't only have to do with fuel volume either.

You will see that it can lift mutch more than 5,5 tonnes payload!

No... yes... well, there is some sort of problem with the mass ratio calculator I used. :shifty:

I would not call the increase "much more". Especially since a lot of it is going to go to either my structure or my on-orbit manuvering propellant.

Its an simulation and some people could imagine "what when it happens"

That's exactly what I'm doing here. Except that in reality, such a failure, would be dealt with by an experienced pilot and the vehicle control system, not a relative novice sitting in front of a computer. :shrug:

Same to your project, as long orbiter doesnt simulate structurally limits and other things, we have only these values and our experience.

No... but I am not incorperating hover engines, retro engines, scram diffusers that melt only at ~10 000 k, hammerspace propellant tanks, magic engines, nosecone docking ports...

Of course I cannot make a 100% realistic vehicle. But I will try to the best of my abilities, and even beyond that. But most importantly, I will try to add more reasoning to my project, than "this is cool" or "yeah, this fits" or "that would make doing (x) so much easier!".

 

[NuttyPro67]

Hey T. Neo, let me just take this chance to pat you on the back, sir! Like you I think it's kind of ridiculous that "near future" concept SSTO can take off vertically using dedicated hover engines with a 10 ton payload then make it to LEO. Seems like a reasonably sized SSTO would either take a small crew to orbit OR a payload, but not both. I've spent quite a bit of time thinking about doing my own "realistic" approach to an SSTO addon(too bad I don't know C++).

At this point, I'm just anxiously awaiting your concept sketches/drawings. Good luck!

 

[N_Molson]

You can't fly to Mars in a 5-seater spaceplane, but then again, you can't cross the atlantic in an inflatable dinghy. So the inability to specialise there is not limited to spaceflight.

You can.

[ame="http://en.wikipedia.org/wiki/Alain_Bombard"]Alain Bombard[/ame] (french biologist & physician)

Seriously, I approve the concept of a "Shuttle DG", as long as it uses a booster to reach orbit.

 

[Fabri91]

I thought T.Neo wanted to do a single stage to orbit space plane based on possible near-future technology...I'm very curious about this project, it looks like it will be a much larger vehicle than the "impossible" DG.

 

[GoForPDI]

Something of similar size to the DG would definetally need a booster. And how about having a rear docking port with Shuttle sized OMS boosters around the hatch? Kinda similar to Kliper, Hermes, or Dreamchaser.

SSTO wise, you would be looking at something like Skylon for something that is ''near'' tech.

 

[T.Neo]

You can.

Alain Bombard (french biologist & physician)

Yes... well, if you want to travel across the Atlantic in only an inflatable raft, subsisting on only fish, be my guest.

It's interesting; in space you already have no air, something that is abundant at the surface of the ocean. To survive in that environment you just need to be out of the water, and have a proper fluid uptake... in space, you have to worry about maintaining the environment in the capsule in the first place, which includes maintaining air quality and temperature.

That is why a lifeboat in the ocean makes far more sense than a lifeboat in space.

Seriously, I approve the concept of a "Shuttle DG", as long as it uses a booster to reach orbit.

Why? Why is it so essential to use a booster?

That is as technostrategically limiting as stating that you can't have a transatlantic airliner, unless it is propeller-driven.

This vehicle does not need a booster, because it's propulsion system (which is nuclear) allows it to reach orbit with a far lower mass ratio than would be required otherwise.

Use of a booster here, results in an immediate massive increase in both complexity and cost; the advantage it gives you, is now redundant due to new technology.

There are plenty of spaceplanes that are launched on expendable boosters. The X-20 comes to mind, as does Hermes, and Kliper. Those are no more than payloads, that happen to be spaceplanes. In fact, 23 days ago (at the time of posting), the X-37B- just such a vehicle, touched down after 224 days in orbit. An orbit it was placed into by an Atlas V.

Even Buran is just a payload, really, despite the sidemount. At least STS carries the actual main engines within it's own airframe.

I'm very curious about this project, it looks like it will be a much larger vehicle than the "impossible" DG.

Pretty much. The actual size of things is the primary problem with the DG in the first place- even with the engines and the mass ratio and the dry mass that it has, it wouldn't be able to carry enough fuel.

And how about having a rear docking port with Shuttle sized OMS boosters around the hatch? Kinda similar to Kliper, Hermes, or Dreamchaser.

I can't put a docking port at the back of the vehicle. The back of the vehicle is some 30 meters away from the crew section, seperated by a propellant tank. That space is also taken up by my radioactive engines... it'd be a bit difficult to add a docking port there.

I'll have to add my docking port up front, on the dorsal side behind the crew section. It isn't all bad; that opens up a space from with antennae, radiators and solar panels can deploy, as well as potentially even a space to store some vacuum-exposed payload.

SSTO wise, you would be looking at something like Skylon for something that is ''near'' tech.

Pretty much, although my overall design differs somewhat due to the different propellant and propulsion.

I am really thinking of adding an airbreathing capability though, as it could enhance performane a great deal... as well as open up more potential launch locations.

I don't like the shape of Skylon much, I think it's ugly... trying to be a hypersonic dart, F-104, spaceplane sort of a beast... but that is for good reason.

My engines are currently at the back, and they're very heavy (mostly due to the shielding). I don't know how I would be able to reposition them in an effort to center the COG.

 

[Moach]

(on the G42)
Probably your best bet, but even then, the engines have a fictional configuration (RAMCASTER; as far as I know, they do not break physics in any way, but they're not strictly based on the operating principles and parameters of any real world design or study).

Please correct me if I am wrong, but I'm not sure if Moach has done any in-depth engineering or physics numbers behind the vehicle.

well, yeah, he didn't....

i did however, research a lot of similar concepts and based my numbers on educated projections of current developments given a couple of decades to mature - but i wouldn't take it as too realistic in a purist way...

i had hand-tuned it to make it interesting to fly, which is why it's meant to "feel" more realistic than it really is.... (i used lookup tables in place of real-time math to simulate the engines)


i still believe that a G42 could be built into a plausible spacecraft, given the needed investment over 20-30 years or so.... but there's quite a lot of ground to cover...

 

[Sky Captain]

My engines are currently at the back, and they're very heavy (mostly due to the shielding). I don't know how I would be able to reposition them in an effort to center the COG.

Wouldn't there be problems with COG shifting seriously when propellant is being consumed. The vehicle would get very back heavy when propellant is depleted and it has to fly well in the atmosphere with full tanks when taking off and with empty tanks on reentry. IIRC that's why the engines of a Skylon are placed on wings so the vehicle remains balanced when evenly distributed propellant tanks are full or empty.

 

[Fabri91]

Does it really have to be stable cg-wise? Many modern fighters have a cg that's located very far back, and remain flyable thanks to fly by wire controls. In orbiter it would be possible to position the cg more forward than it would be and then pretend it had a fbw system, for the sake of doability.

 

[T.Neo]

Yes, well, back heavy with propellant is not that bad... by then, you are outside the majority of the atmosphere, it becomes a physics game. Your main concern then is overcorrections and errors in the guidance system, as aerodynamics does not come into play (as much as it would earlier on).

And it is also something that current LV designs have to cope with, to varying degrees.

The mass distribution problems with HOTOL were as follows:

During development, it was found that the comparatively heavy rear-mounted engine moved the center of mass of the vehicle rearwards. This meant that the vehicle had to be designed to push the center of drag as far rearward as possible to ensure stability over the entire flight regime. Redesign of the vehicle to do this cost a significant proportion of the payload, and made the economics unclear.

So it's more of an aerodynamics thing than anything else, at least, as I can understand it.

The Skylon solution is interesting, but there are serious problems with it's implementation here, primarily concerning neutron scattering and radiation shielding.

 

[Urwumpe]

Does it really have to be stable cg-wise? Many modern fighters have a cg that's located very far back, and remain flyable thanks to fly by wire controls. In orbiter it would be possible to position the cg more forward than it would be and then pretend it had a fbw system, for the sake of doability.

You don't have all freedom for FBW, you can only have the CoG where you can still control it by the control surfaces and still control in which direction you fly. It is a design decision.

Also, fighter planes don't really have the CG far back, but have the center of lift closer to the CG.

 

[Fabri91]

Thanks for the heads up, makes sense...

but regarding the position of the cg: what flight profile would such a spaceplane have? Would it "fly out" of the atmosphere like the DGex or would it accelerate very fast like the deltaglider or any nomal booster? I ask because if it got out of the thickest part of the atmosphere fast, wuldn't it make more sense to optimize the design so that it would be "more flyable" on reentry, with a very low fuel level?

 

[Urwumpe]

You generally design a spaceplane, that it survives reentry at all. which is a very narrow line of options. The Shuttle for example, can only reenter on a very narrow island of weak stability at 37.5° AOA (imagine a hill top). More and it would flip over, less and it would flip over, because the heavy main engines make it prefer to fly tail first.

You could have a bigger range of AOAs, but then, you would get problems during landing, since the plane would be instable at subsonic speeds then.

 

[T.Neo]

Flight profile would probably be something like the Deltaglider; it would not linger forever in the atmosphere like the DGex, but it would not attempt to punch through the stratosphere immediately like conventional launch vehicles.

If I implement airbreathing engines, it would probably linger in the atmosphere- climb relatively slowly and accelerate to a Skylon-like 26 km mach 5, and then pursue a more rocket or deltaglider like flight plan from there.

I ask because if it got out of the thickest part of the atmosphere fast, wuldn't it make more sense to optimize the design so that it would be "more flyable" on reentry, with a very low fuel level?

What do you mean? Retaining a small amount of fuel to compensate for errors during reentry?

I've always imagined the vehicle having to dump excess propellant... I don't think a ton or so of cryogenic methane sloshing around a rapidly warming delicately constructed metal container is a good thing.