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Re: Space Shuttle

Postby Thorsten » Sat Nov 24, 2018 4:11 pm

A throttle down to 67% may occur prior to fine count if the center engine is failed due to the
incorporation of CR 91042 Second Stage Pitch Gimbal Relief in OI-26. This CR compensates for
potential gimbal saturation due to the super light weight tank (SLWT). The SLWT is about 8,000
lbs lighter and causes the vehicle center of gravity (cg) to move about 6 to 8 inches further up into
the Z-axis at MECO. This higher cg makes controlling the vehicle difficult for press to MECO
cases with the center engine out when the orbiter Zcg is near the top of the entry cg box


Now that's interesting - so the last-second control problem with the center engine gone is actually real.
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Re: Space Shuttle

Postby wlbragg » Sat Nov 24, 2018 5:44 pm

Can anyone verify the hand hold railing on the payload bay in reality are actually attached to the doors and move into position as the doors are opened?

KU-Antenna, what are the "exact" steps to deploy it into position?
I read the post that summed up the procedure including the breakers, but i can't get the antenna to move.
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Re: Space Shuttle

Postby Thorsten » Sat Nov 24, 2018 6:05 pm

KU-Antenna, what are the "exact" steps to deploy it into position?
I read the post that summed up the procedure including the breakers, but i can't get the antenna to move.


* payload bay door open
* ANTENNA ELEC circuit breaker ON
* ANTENNA SIG PROC circuit breaker ON
* KU ANTENNA HEATER circuit breaker ON
* electrical power available
* switch to DEPLOY

Yes, that's all

Code: Select all
      <switch name="systems/mechanical/ku-antenna-ready">
         <default value="0.0"/>
         <test logic="AND" value="1.0">
            systems/mechanical/ku-antenna-elec-cb == 1
            systems/mechanical/ku-antenna-sig-proc-cb == 1
            systems/mechanical/ku-antenna-heater-cb == 1
            systems/electrical/total-available-power-kW GT 0.0
            systems/mechanical/pb-door-right-pos == 1
         </test>
      </switch>


Works like a charm.
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Re: Space Shuttle

Postby wlbragg » Sat Nov 24, 2018 7:26 pm

Thanks!
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Re: Space Shuttle

Postby wlbragg » Sat Nov 24, 2018 10:20 pm

Do I recall a discussion about this happening, the stow position of the KU antenna after being deployed? What is the issue, other than the obvious that it isn't orientated correctly?
I'd be more that happy to fix it, but would like to know if there is any information yet known as to why it is happening. Do we know why this is happening?

Image
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Re: Space Shuttle

Postby eatdirt » Sun Nov 25, 2018 12:59 pm

Hi Wayne,
yes, the antenna does not get stowed properly. It looks like when we stow it, it starts from the position it is actually pointing to and do some sequence of motion from there. Depending on the starting position, it may not fit into the payload bay at the end.

I suspect a fix would be to first move back to some "before stow" standard position and then triggers the stowing sequence.

When this happens, and I am patient enough to not jettison the antenna, I do this by hand actually. You can take manual control of the antenna on the aft panels and change azimuth and elevation with the switches, then you can align it properly and stow it fine:

Image

Cheers,
chris.
Last edited by eatdirt on Sun Nov 25, 2018 1:05 pm, edited 2 times in total.
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Re: Space Shuttle

Postby eatdirt » Sun Nov 25, 2018 1:02 pm

there's no warm freon coming in, so my understanding is that temperature at the evaporator should decrease


Yes, I've understood that as well. I am even perverting it to actively cool the freon sometimes, for the multiple reentries, that allows bypassing opening the bay doors during one hour in tail to sun position... :twisted:
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Re: Space Shuttle

Postby Thorsten » Sun Nov 25, 2018 2:23 pm

yes, the antenna does not get stowed properly. It looks like when we stow it, it starts from the position it is actually pointing to and do some sequence of motion from there. Depending on the starting position, it may not fit into the payload bay at the end.


Is the problem that the antenna visuals are not okay, or is the antenna system-side not stowing (aka, the payload bay doors are prevented from closing?

In other matters, after starting to read the Ascent Abort Flight Handbook, I've been adding a few options to i-load more fine-grained control over the launch profile. You can now define the thrust bucket time window as well as depth, you can request, you can loft the trajectory and get MECO at somewhat higher altitude (note: this is risky for aborts...) and request an OMS assist burn. The latter is probably interesting for the extremely high orbits, as burning OMS propellant early means the MPS has to lift less weight, so it should be more efficient than MPS + OMS-1 burn separately.

I will still experiment some with trajectory lofting by biasing the stage-1 climb angle.

Generally these are not 'safe' options in the sense that choosing the parameters outside some good range is likely to kill you - basically you can push the profile further to the edge for your particular launch setup to squeeze the last bits of performance out, but the further you push the riskier it gets.
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Re: Space Shuttle

Postby GinGin » Sun Nov 25, 2018 2:44 pm

Nice catch for the centre engine :)
You must have coded that well to observe some effects like that .

This handbook is really nice :)

Concerning Freon stuff, I checked the rad in Temp on spec 88 and indeed it is increasing with no flow in the loop.

It might make sense that the Freon stuck in the evap process becomes colder. The evap out Temp probe is located after, so yes it might be like that. The Freon around the evap stuff get colder by convection will the rest get hotter

Avionics bay and cabin T increase as expected .
So it will be an interesting scenario for an AoA :)
Time pressure to land, to thermally shed the non essential stuff and not overheat the IMU


I am reading again the eclss workbook , I am still amazed by the complex thermal management

.

Would it be possible to add a master caution for the low Freon flow ( it should lighten in yellow below 1200 lb/hr) ?

And I was thinking , could we add the master caution klaxon sound ? :)
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Re: Space Shuttle

Postby Thorsten » Sun Nov 25, 2018 3:07 pm

Would it be possible to add a master caution for the low Freon flow ( it should lighten in yellow below 1200 lb/hr) ?


Yes, that should be easy.

And I was thinking , could we add the master caution klaxon sound ? :)


Adding one is easy once we have one (I suppose I'm not entirely in the clear how it's switched off either...)
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Re: Space Shuttle

Postby eatdirt » Sun Nov 25, 2018 4:05 pm

Is the problem that the antenna visuals are not okay, or is the antenna system-side not stowing (aka, the payload bay doors are prevented from closing?


Well, facts are that the visuals are not ok and the doors are closing, so this is no issue for the simulation, although you have a piece of antenna, or more traversing the shuttle wall or payload bay doors :)

But, forgetting that the antenna can traverse any surfaces, I would rather say yes, the current stowing procedure would be preventing the payload bay doors for closing, most of the time in fact.
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Re: Space Shuttle

Postby GinGin » Sun Nov 25, 2018 4:06 pm

The game ssms2007 have pretty good sound on it .

I can record you some caution warning , a two tone bip

I got also a good workbook on caution and advisory system :)
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Re: Space Shuttle

Postby Thorsten » Sun Nov 25, 2018 4:25 pm

The game ssms2007 have pretty good sound on it .


We can't use that without permission - license issues.

But, forgetting that the antenna can traverse any surfaces, I would rather say yes, the current stowing procedure would be preventing the payload bay doors for closing, most of the time in fact.


You're not approaching this from a coding perspective - from a coding perspective this means the problem is just the visuals that are off rather than systems simulation. You can land on a gear that's extended in the FDM, even if there's no visuals for it - but you can't land on correct visuals with no FDM to support it. :mrgreen:
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Re: Space Shuttle

Postby wlbragg » Sun Nov 25, 2018 4:29 pm

@GinGin, from what I saw that game and any of its resources is not GPL compatible so we couldn't use in our project.

facts are that the visuals are not ok and the doors are closing,

It appears to be only the visual that is at issue.

@Thorsten, I can look at it and see if I can decipher what is going on and program an animation to fix it. I don't know anything about any of the Shuttle communication programs or procedures as it related to the movement of the antenna, ie: auto-tracking movements VS manual. If it is capable of both that might add a layer of complexity to it. I guess we need a set position that can be achieved when the stow command is executed as @eatdirt stated.
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Re: Space Shuttle

Postby eatdirt » Sun Nov 25, 2018 8:24 pm

You're not approaching this from a coding perspective


Mmm no, you're the engineer, I am a rookie pilot :D

Seriously, I know, but what I don't know is if the coding is just binary, antenna stowed or not stowed. In that case, everything works fine. If the coding says, stowed antenna is oriented azimuth=x elevation=y, then, from the visuals, I would say x,y are wrong.

Just read your post for the i-coding during ascent, very cool, I'll try the MPS/OMS combo! Thanks!
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