CEV Orion, 606 update

[myles]

Reentry-stream is much too big (don't know really why). You may give it a try and do some testing. Please give me some feedback on the visual appearance and the flight behaviour.

That reentry stream thing happens to me in AMSO, too. When I open the solar panels, they are bright even at night. You probably already know this, but there are RCS thrusters at launch, which prrrroooobably shouldn't be there . I like it, though!

 

[FlyGirl]

The models are really looking good. Very nice work. The only problem I have found so far that hasn't been mentioned is that when launching with the Ares the interior point of view is fixed outside below the Ares rather than in the Orion capsule.

Handling seems good to me but RCS rates feel a bit slow. I don't know the mass and thrust values for the real Orion package though so I can't make a qualified judgment here.

Thanks for a very nice ship. Keep up the great work.

To give you something to play with, I publish a

You may give it a try and do some testing. Please give me some feedback on the visual appearance and the flight behaviour.

 

[Cale]

Wow Franz, this is a very nice flying machine you're building...:speakcool:

Couldn't get the hatch to open (not sure if it's supposed to) but visually, it's stunning. I like the new textures for the VC, too, though it seems like the viewpoint is a bit too far forward. Is there any way of changing this in either the config/mesh file myself?

Great job! It's going to be superb once it's completed

Cheers,

Cale

 

[francisdrake]

Thanks for the first reports! I am glad the update runs without nasty side effects

- Reentry stream: The size is set, but I will try it with a smaller number.
- Hatch animation wrong: I will fix this after the mesh update is finished,
because the mesh group number changes when adding or deleting meshes.
- CM RCS thrusters not aligned to texture: Will fix it on the next release.
- Viewpoint outside while on ARES: Will fix that. (It is an heritage code from my unmanned Delta IV launcher, where the outside view is nicer than looking at the inside of the payload fairing
- Bright solar panels: This I even didn't notice yet. Will check if I defined the material accidently self-illuminated.
- RCS thrusters at launch: This is a hack to save me from thrust vectoring
Will have a look into it when correcing the launcher (this will be a little later).
- RCS sluggish: Yes. RCS thrust is correct (a least to published figures), location of RCS thrusters is a little weird. Will have a look the inertial moment and probably reduce it, to avoid overshooting rotations in autonav modes.

 

[Kyle]

Just to let you know when the Orion comes in to re-entry, it tilts to the Left..

 

[Opie]

I am pretty sure it is supposed to. A heads down lifting reentry i believe.

 

[mbartley]

excellent add-on

I had a great time trying your new CEV. I just launched and flew it to ISS and docked. I flew a pretty bad 1st stage ascent (AOA too high and stage separation too low in the atmosphere), but I managed to hit a roughly 70km x 250km orbit, perfect for an apogee burn to begin catching up to ISS. After that and other necessary maneuvers, I docked with 48.1% fuel remaining. Was it supposed to only have 60% after jettison from the 2nd stage?

RCS seemed to sometimes do weird things, though I couldn't pin down exactly what has happening. I think sometimes roll thrusters caused rotation in other axes as well, and sometimes translational RCS caused rotation. Fortunately none of that happened during docking.

I didn't notice the "bright solar panel" effect mentioned earlier.

 

[francisdrake]

For missions to the ISS the CEV is fueled up only ~60% to save weight. This is enough fuel for ISS rendezvous and reentry.

The reentry is intended heads-down. The mass scenter has a built-in offset, so the capsule produces some lift during hypersonic travel and flattens out the reentry trajectory. This reduces the maximum G-load to ~3.5 G.

 

[mbartley]

For missions to the ISS the CEV is fueled up only ~60% to save weight. This is enough fuel for ISS rendezvous and reentry.

OK, that makes sense. Do you know if IRL the CEV fully-fueled for lunar missions will be launched on Aries I? I'm not sure I would have been able to reach orbit with the extra payload mass.

The reentry is intended heads-down. The mass scenter has a built-in offset, so the capsule produces some lift during hypersonic travel and flattens out the reentry trajectory. This reduces the maximum G-load to ~3.5 G.

I've only tried one re-entry so far and indeed that's what seemed to happen. Aerobrake MFD didn't seem think it would though. Early in reentry it predicted a peak decelleration of 12.5G!

 

[francisdrake]

Questinoing if a fully fueld CEV can be lifted by the Ares 1:
This seems to be a real concern for NASA. I tried it in the simulation, and it worked, because it is launched directly east (not to the 42° inclined ISS orbit), and here earth rotational speed gives an extra bonus. I had no problem reaching a 220x220 km parking orbit with a fully fueld CEV with 4 astronauts.

Launching will become more tricky with an Ares 1 closer to publised specs. The booster delivers less power, and during the middle part of the second stage burn the vessel has to point upward 40° to avoid dropping back into the denser atmosphere.
(This straightens out during the final phase of the burn). I tweaked the ISP numbers by 10% (Orbiter bonus ), but had only 0.9% fuel left after orbit insertion.

 

[francisdrake]

Made a new mesh of the CM. The front windows are bigger, the side windows were deleted. The pic below shows 'crew integration' with an Ummu-astronaut in the co-pilot seat. Got Dansteph's permission to use the crew 'indoors', if the addon is Ummu-compatible

 

[mikey451]

Questinoing if a fully fueld CEV can be lifted by the Ares 1:
This seems to be a real concern for NASA. I tried it in the simulation, and it worked, because it is launched directly east (not to the 42° inclined ISS orbit), and here earth rotational speed gives an extra bonus. I had no problem reaching a 220x220 km parking orbit with a fully fueld CEV with 4 astronauts.

Launching will become more tricky with an Ares 1 closer to publised specs. The booster delivers less power, and during the middle part of the second stage burn the vessel has to point upward 40° to avoid dropping back into the denser atmosphere.
(This straightens out during the final phase of the burn). I tweaked the ISP numbers by 10% (Orbiter bonus ), but had only 0.9% fuel left after orbit insertion.

Franz,

Do you have a reference for trajectory information - both lateral and vertical? I've been assuming that the trajectory is "gravity turn" longitudinally, until the 2nd stage reaches about 20 deg., then holding 20 deg until after the "roller coaster". For lateral, I've been assuming that beta was zero until after about 30 deg, when dynamic pressure is low, then I fly to the orbital plane. I've also seen references to 90 deg. heading launches, however, but also "yaw steering" late in the profile, implying that there is some attempt to match inclination prior to MECO. Do you have any references you can point me to?

Thanks,
Mike

 

[DaveS]

(not to the 42° inclined ISS orbit),

ISS has an orbital inclination of 51.6°s, not 42°s!

 

[Urwumpe]

Launching will become more tricky with an Ares 1 closer to publised specs. The booster delivers less power, and during the middle part of the second stage burn the vessel has to point upward 40° to avoid dropping back into the denser atmosphere.
(This straightens out during the final phase of the burn). I tweaked the ISP numbers by 10% (Orbiter bonus ), but had only 0.9% fuel left after orbit insertion.

The acceleration profile of the second stage should be pretty similar to the Ariane 5 sustainer (EAC) after booster (EAP) separation, so why not test a similar profile and throw the second stage literally into orbit by the first stage?

Let the stack gather more vertical velocity until first stage separation, and allow the second stage a significant drop after passing the first apogee. This means the first stage has to deal with a part of the gravity losses of the second stage and the second stage can concentrate more on gathering velocity. Should buy you enough propellant reserves to lower the Orbiter Bonus a bit.

If it is possible to launch the ATV in Orbiter with nearly realistic numbers, such a flight profile and manual flight, why not try it on the CEV?

(I personally think, 10% bonus would be better fitting into the "beginners" mode - complex flight model disabled)

 

[Brad]

Made a new mesh of the CM. The front windows are bigger....

WOW! This is looking really awesome! :thumbsup: I am so looking forward to the finished product.

 

[simcosmos]

Let the stack gather more vertical velocity until first stage separation, and allow the second stage a significant drop after passing the first apogee. This means the first stage has to deal with a part of the gravity losses of the second stage and the second stage can concentrate more on gathering velocity. Should buy you enough propellant reserves to lower the Orbiter Bonus a bit.

If it is possible to launch the ATV in Orbiter with nearly realistic numbers, such a flight profile and manual flight, why not try it on the CEV?

(I personally think, 10% bonus would be better fitting into the "beginners" mode - complex flight model disabled)

The 'problem' is that AresI first stage should be recoverable for, at least, inspection (not even talking of reuse), which constraints its flight envelope (and by consequence, the flight envelope of the upper stage, remembering that NASA wants such upper stage to be powered by a single J-2 derived engine >> things would be a lot easier if assuming an SSME class thrust at SRB separation but that would probably mean something like 2 x J-2 derived engines, which is less good for part of the LOM numbers, depending of assumptions).

About using or not '10% bonus': I would prefer to not use it

As a side note, I'm slowly updating the launcher 3D models (SRB, interstage, US, ALAS, adapter, etc): then will use some of the latest masses / performance specs for AresI as well will add a few extra mass to counter the SRB induced oscillations.

Then will play with the expected lunar CEV top mass and see if will need to introduce a few extra updates to AresI... either update ascent events (such as when to release the SM covers as well the LAS) and / or eventual performance upgrades (such as assuming non recoverability of SRB, higher ISP, etc)...

However, assuming non recoverability of SRB is like... dropping one of the *key* reasons - from safety point of view - for using a solid as first stage for the CLV...

I could provide extra information but would first need to check information sharing constraints. In any case, NASA's Technical Report Server has some good PDF with info about things such as AresI performance analysis, CEV abort modes, etc.

António

 

[Urwumpe]

Actually, letting the first stage gather more vertical velocity would not impair it's reuse much, the resulting steeper trajectory would just mean that parachute timing has to be modified, so that the parachutes don't need to be reinforced. But on the other hand, staging would happen higher and at lower Mach numbers.

The total Delta V the first stage can create is always constant, the final state vector at staging just depends on how much of this total Delta V gets used for countering drag and gravity or for off-plane maneuvers and control.

EDIT: BTW, you can also call the 10% NASA bonus. I have the impression that NASAs development teams of the Ares I and the Orion CEV are not cooperating well. There seems to be a tiny lag behind Orion CEV changes and when the Ares I is adapted to the new payload demands.

 

[Cale]

Wow, the new mesh looks great...glad to see that it's UMMU compatible

Looking forward to the finished product!

Cheers,

Cale

 

[FlyGirl]

I agree it's looking very nice indeed. I eagerly await the finished version myself!

 

[simcosmos]

Actually, letting the first stage gather more vertical velocity would not impair it's reuse much, the resulting steeper trajectory would just mean that parachute timing has to be modified, so that the parachutes don't need to be reinforced.

I'm not an aerospace professional but suspect that things might not be as easy and as-apogee-free-of-constraints as just changing the pitch program for the AresI first stage (also when having in consideration other eventual first stage recovery considerations for this specific launcher configuration, some CEV abort scenarios, etc). Recovering the 5 segment SRB used on AresI might not be as 'easy' as recovering current SRB used in STS or when comparing with 5 segment SRB being used in heavy lifter configurations, but again, I'm not an aerospace engineer. As a side note, loosing recoverability might also be additionally interpreted - in some circles - as loosing the recovery system mass itself.

Anyway, until word in contrary, AresI first stage is to be recovered and reused for ISS and Exploration Missions.

EDIT: BTW, you can also call the 10% NASA bonus. I have the impression that NASAs development teams of the Ares I and the Orion CEV are not cooperating well. There seems to be a tiny lag behind Orion CEV changes and when the Ares I is adapted to the new payload demands.

About the margins: AresI + Orion should, in theory, have their own margins (and also margins as a system). Adding 10% on top of that, even if when making a first order implementation / simulation of the rocket equation and if using data derived from public sources might be more than a bonus. Of course this is just my opinion and, in the end, it is francisdrake's decision to add any thrust / ISP, etc margin, if wanting to improve the playability in Orbiter.


Regarding the coordination of work between AresI and Orion teams: will not comment unless to say that the teams are doing their best under the configuration constraints they are given to work with. This also to say that when making a simulation / implementation in Orbiter the best should probably be to freeze such implementation for a given set of AresI-Orion assumptions (design development review parameters) and/or else make coherent extrapolations for masses, engine specs, payload requirements, mission procedures, etc based on latest known data (instead of somehow applying artificial factors, which might not be needed, for given specific sets of those assumptions).

António

PS: sorry Franz, for the boring talk, will be in 'away mode' now (might one day - not sure when - send updated AresI meshes in your way or else might release something at OHM and then, if wanting, feel free to extract the 3D or performance, etc updates to your addon, like the last time )