Most excellent X-37B pix!

[Zathros]

"The spacecraft had three solid-fuel, 1000 lbf (4.5 kN) thrust retrorockets that fired for 10 seconds each.[15]:28 One was sufficient to return the spacecraft to Earth if the other two failed. The firing sequence (known as ripple firing) required firing the first retro, followed by the second retro five seconds later (while the first was still firing). Five seconds after that, the third retro fired (while the second retro was still firing)."

The nozzles were not aimed as far out as most models depict them. Sequential firing means one lit after another, while the previous rocket is STILL lit. It was the spoiler flap on top of the nose cone capsule that flipped it around and did most of the correction during re-entry into the atmosphere. At this point, the forces involved would not have allowed the capsule to do much except slow down , or change course a little, it was going really fast, backwards, and the spoiler plate assured the capsule, with it's c.g. well aft, stayed that way.

How can anyone be so sure that the rocket shown in the picture is the actual craft. The foam blocks are very pliable, easy to move, serve the purpose well. Did anyone notice the other craft in the last picture? It was not in front of a mirror. I would also bet the nozzle vectors. There will be much about this craft and it's variants, (i.e. crew configurations) that will not come out for many years, if at all, carrying a crew is part of it's funding profile mandate. Deep, quick isertion, is another mandate. Space is about defense. There will be a lot less sharing going on, and when the U.S. pulls out of the I.S.S, it will be over and the U.S. will scuttle it.

[Paper Kosmonaut]

On the other X-37b you can see a NASA logo. It is the test vehicle, used for drop tests when the project still was coordinated by NASA. At Nasaspaceflight I read somewhere they intend to have two flight articles, not including the "NASA-plane".

[umtutsut]

Originally Posted by Retired_for_now

Guess I'll continue trolling for a consensus on X-37 - at least until Les finds more pictures.
Yogi

The schematic on this Space.com board shows only one engine...but it looks as if it's on the centerline. Could be an artifact of the angle, tho.

Space.com Forums | View topic - X-37B launch in April 2010


Les (Friendly Airplane Asylum & ex-NASA flack)

[Retired_for_now]

Yah - but schematic also shows previous hydrogen-peroxide propulsion. Apparently X-37B was switched to bi-propellant to use existing/proven hardware. Two engine info came from NASA tech paper on the switch.
Ah well, it's just a model (he said, with his OCD twitching ...) so I'll put one engine on centerline and call it close enough (another version to test build).
Yogi

[Paper Kosmonaut]

The nozzle appears to be placed on a flat cone shape structure. Does that imply a thrust vectoring system?
Also, in that case, ...maybe... off-center and angled thrusting? (wut? huh? why?) Arrgh, I might just be a trick of the eye. The angle in which the photographer took the picture. I don't know...

[mercsim]

The "spoiler flap" is actually mis-labeled. That photo has been around for several years and has been edited and labeled (often wrong) several times.

Its actually called a destabilizer flap (or de-stabilizer, depending which McDonnell reference you look at).

Its purpose was "to break a possible freeze if the stable capsule should reenter the atmosphere small end forward..." It was also useful in orienting the capsule in certain aborts in the lower atmosphere. If the capsule started re-entry from space anywhere near a normal attitude, it wasn't required.

Ref: Big Joe 1 Flight report, This New Ocean pg. 199-206, Mercury Familiarization Manuals dated 1959-1962

[Paper Kosmonaut]

Hey Scott, good to have you aboard here, too. I am amazed with your Mercury knowledge. Hopefully we can appeal upon it now and then.
PK

[Zathros]

Originally Posted by mercsim

The "spoiler flap" is actually mis-labeled. That photo has been around for several years and has been edited and labeled (often wrong) several times.

Its actually called a destabilizer flap (or de-stabilizer, depending which McDonnell reference you look at).

Its purpose was "to break a possible freeze if the stable capsule should reenter the atmosphere small end forward..." It was also useful in orienting the capsule in certain aborts in the lower atmosphere. If the capsule started re-entry from space anywhere near a normal attitude, it wasn't required.

Ref: Big Joe 1 Flight report, This New Ocean pg. 199-206, Mercury Familiarization Manuals dated 1959-1962

Regardless of what it was called, it did the same thing. I have heard it called both. The same nomenclature changes also happens in aircraft, like the "Oh My God " bolt attached to the elevator, in the rear of Piper Warriors, (140/180) series. If it's loose or broken, that is the last thing you will say.

[mercsim]

I hate to nitpick but as an Engineer, its important to get facts right, especially historical ones. When we make a small mistake, it gets propagated and keeps getting worse. I mean no dis-respect but I think its important that we quote history correctly.

"the spoiler flap on top of the nose cone capsule that flipped it around and did most of the correction during re-entry into the atmosphere" Actually, it did none. The heat and aerodynamic forces usually destroyed it, probably quickly. This is evident on many of the Spacecfraft Films shots. In a worst-case scenario, if the capsule started to re-enter nose first, it would naturally flip around. However, the Engineers were concerned it could get "stuck" long enough too burn something up since there was no heat protection on that end.

"the spoiler plate assured the capsule, with it's c.g. well aft, stayed that way" It was not intended to do this. Its job was to perform a function that was never expected to be encountered; a momentary aerodynamic condition that could have caused heat damage to the recovery system.

There is more than one of "those" bolts in the Piper Airplanes, most airplanes, and most spacecraft. There was only one small pin holding the main parachiute onto the Mercury Capsule and it had an explosive inside it! Its kind of like an Urban myth, it gets propogated into some big thing that Engineers take for granted and think is not really a big deal.

The destabilizer flap could more likely be compared to a seatbelt. You hope you never need it, and shouldn't, but if you do, it does a momentary job that really makes a difference. No subsequent spacecraft ever had anything like it as Engineers understood the problem better and were more confident in Stabiliziation (autopilot) systems.

Scott
spacecraftreplcias.com

[Retired_for_now]

For Scott - on (smaller) helicopters I believe it's the "Jesus" nut on top the rotor mast ... along with thousands of other unrelated parts flying in loose formation as the helo beats the air into submission (yah, I'm a fixed wing guy). Anyway, I appreciate the precise detail.

Back to the X-37. Looking at everything Les found, and wandering the internet wasteland for a few more items, it looks like OTV-1 has a single, bi-propellant rocket mounted slightly off-center to starboard (one assumes it's gimballed so it can align with the spacecraft's CG when fired, or hard mounted to achieve the same thing). There are a couple of views in the photos and videos from the starboard side and directly aft while it was towed ...

So, one more update to the aft bulkhead on the model. As for why ... my first guess would be that the mount was the simplest way to put the engine into the existing NASA airframe; and that airframe may have originally had mounts for two smaller rockets as referenced in the Boeing technical paper on X-37 storable propulsion systems.

Wonder what OTV-2 will look like?

Yogi