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Space Shuttle - Development

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Re: Space Shuttle - Development

Postby eatdirt » Thu May 30, 2019 1:23 pm

Is it possible to change somewhere the thrust pourcentage for ascent


I guess I know a way for that one, SPEC 51 settings before ignition, Throttle -> Max. But you get only 3 options, nominal, max or abort.

By the way, I was just curious to see what a manual ascent does, and I spotted that the pink needles do not work on the big ADI ball display, but do work on the small one. Do you see that Gingin?
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Re: Space Shuttle - Development

Postby Thorsten » Fri May 31, 2019 12:43 pm

There's now a HST mission file - if you launch quickly, you should get to a decent intercept (as I discovered to my dismay, marginal inclination targeting is tricky and guidance gives me some offsets... so far we have to live with 0,25 deg rinc, but generally the scenario seems doable as far as I've tested - last known position was about a deg behind HST after insertion, so enough time to do the PC burn and do the rendezvous 2-3 orbits later.
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Re: Space Shuttle - Development

Postby Thorsten » Fri May 31, 2019 12:45 pm

Is it possible to change somewhere the thrust pourcentage for ascent


Not without changing the code.

Is it possible to have at game start MET instead of GMT dispayed on CRT 1 through 3?


I read somewhere (?) that it starts with GMT... There's always the big MET display in the cockpit.
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Re: Space Shuttle - Development

Postby GinGin » Fri May 31, 2019 5:53 pm

eatdirt wrote in Thu May 30, 2019 1:23 pm:
Is it possible to change somewhere the thrust pourcentage for ascent


I guess I know a way for that one, SPEC 51 settings before ignition, Throttle -> Max. But you get only 3 options, nominal, max or abort.

By the way, I was just curious to see what a manual ascent does, and I spotted that the pink needles do not work on the big ADI ball display, but do work on the small one. Do you see that Gingin?



Hey Chris.
Yep for the Spec 51, but it is available in stage 2 and not during the first part of ascent.

Well, manual ascent does what you want her to do ahah. Basically really similar to the AP, with a slightly less vertical profile to have more downrange at SRB separation. (And decrease the MECO time)
The tough part is between Mach 0.9 and 1.6 where max AOA is + 2°.
If you pull too hard, wings will blown, quite entertaining to do it manually.
I can make a short video if you want (?)


For the needles on the big ADI, I would say it is normal as the Big one is for Orbit use only.


- last known position was about a deg behind HST after insertion, so enough time to do the PC burn and do the rendezvous 2-3 orbits later.


Thank you for the scenario
A deg is perfect, with a slow phasing, plenty of time yes.
I remember doing a 4 Orbit Rendez Vous being 20 ° behind ISS after MECO .


I read somewhere (?) that it starts with GMT.


Interesting, didn't know that one.



I made some test on the new Orbital_target.nas.
I have the feeling that it is more accurate, I need to compare the screens I made from older ones.

I am looking mainly at the catch up rate vs delta height. ( In one orbit, 50000 feet of downrange covered for a 10000 feet of delta height at lowest point and 1 ° of phasing/hour = 10 Nm Delta height = 60 Nm of downrange roughly)

Above 54 Nm, I had the feeling it was much more accurate than thte previous model.
Below 54 Nm, I had some " weird " relative height position.


Next picture, Minimum of relative height at -2000 feet

Image



Maximum around -20000 feet

Image


So all good so far. But I was expected to come back 2000 feet below ISS, as ISS and Shuttle are close enough to be affected by the same amount of non spherical gravity and keep the same relative deltaheight profile without burn.
And What I had ( like if ISS was still not affected by J3/IERS, on a perfectly undisturbed Circular Orbit)

Image


Don't know what came up from your tests ?

PS: I think I found one possible cause for my mysterious jump on X axis.
It happened when I played with time compression of less than one

Time to go for Hubble :D
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Re: Space Shuttle - Development

Postby Thorsten » Fri May 31, 2019 6:55 pm

And What I had ( like if ISS was still not affected by J3/IERS, on a perfectly undisturbed Circular Orbit)


Sorry - why is that result what you'd expect for ISS unaffected by J3?
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Re: Space Shuttle - Development

Postby GinGin » Fri May 31, 2019 7:27 pm

Because I dont understand why the relative height suddenly increase when it shouldn't ( didn't add any extra velocities)
Shuttle was 2000 ftish below ISS, on a very close Orbit from ISS
So roughly one Orbit later, it should come back at the same position ( blue point ) keeping the same relative separation, plus or minus epsilon, and not have that divergence

Unaffected is not quite the right word, more like a different gravitationnal gradient when I would expect two objects on almost a same orbit to be influenced by a same amount.



Image
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Re: Space Shuttle - Development

Postby wkitty42 » Fri May 31, 2019 8:17 pm

GinGin wrote in Fri May 31, 2019 7:27 pm:Because I dont understand why the relative height suddenly increase when it shouldn't ( didn't add any extra velocities)
Shuttle was 2000 ftish below ISS, on a very close Orbit from ISS
So roughly one Orbit later, it should come back at the same position ( blue point ) keeping the same relative separation, plus or minus epsilon, and not have that divergence

maybe i'm not understanding properly but isn't it possible that each craft has different apogee and perigee points? in other words, the ISS max altitude point over the earth might be over Vandenberg at some point in time whereas the shuttle's may be over London at that same point in time... when the craft are close together, this difference may be very noticeable... the only time i'm aware of them being exactly the same would be when they are docked together*...


[*] i see this when tracking satellites using TLE (two/three line element**) files... when a craft flies to the ISS and docks, the TLEs of the ISS is copied to the TLE of the craft so they have the exact same numbers (other than the orbit number)... before docking, each has their own numbers... when they undock and separate, they are once again using different numbers...

[**] in my TLE processing software that i wrote, i prefer to use 1LE, 2LE, and 3LE specifically to differentiate whether the 'T' stands for 'Two' or 'Three'...
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"Why not?" said Gurder.
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Re: Space Shuttle - Development

Postby Thorsten » Sat Jun 01, 2019 3:49 am

So roughly one Orbit later, it should come back at the same position ( blue point ) keeping the same relative separation, plus or minus epsilon, and not have that divergence


Yeah, but that outcome (very approximately closed orbit) should be true even if the target moves on a perfect circle, so I readily see why there's a problem, but not why the problem is that J3 isn't working.
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Re: Space Shuttle - Development

Postby Thorsten » Sat Jun 01, 2019 8:42 am

Okay, I've done a time series of three orbits in a plot - there's a spurious sine pattern (which I can eliminate), but it's all still periodic, so there's still no way to explain a situation that does not return to the same altitude after an orbit.
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Re: Space Shuttle - Development

Postby GinGin » Sat Jun 01, 2019 11:32 am

but isn't it possible that each craft has different apogee and perigee points? in other words,


Yes indeed.
One way to cancel that in some Space Rendez profile vous is co elliptic burn, to match apogee and perigee.
But in our case, it doesn't really matter, as we are looking at a relative height difference pattern
Orbit are almost circular


when they undock and separate, they are once again using different numbers


Yep, usually, There is a separation burn after undocking and last checks done.
So parameters start to diverge again slightly



Okay, I've done a time series of three orbits in a plot - there's a spurious sine pattern (which I can eliminate), but it's all still periodic, so there's still no way to explain a situation that does not return to the same altitude after an orbit.


Thanks for having a look at that :)
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Re: Space Shuttle - Development

Postby eatdirt » Sat Jun 01, 2019 7:49 pm

Image

Can we grab it with the canadarm? If yes, from where?

It is beautiful guys, well done! Any chance to make it mirrorish-like like it is in real life?
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Re: Space Shuttle - Development

Postby wlbragg » Sat Jun 01, 2019 8:11 pm

Any chance to make it mirrorish-like like it is in real life?


Sure, I think we can put a shine on it, can you find me a good reference picture?
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Re: Space Shuttle - Development

Postby legoboyvdlp » Sat Jun 01, 2019 8:23 pm

Does this image work for you? Sorry - it loads on my chrome on Android, hope it works everywhere

https://www.google.com/search?q=hubble+ ... tQ78nUnBdM
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Re: Space Shuttle - Development

Postby eatdirt » Sat Jun 01, 2019 8:29 pm

Am I dreaming, or I do see a second canadarm on the left? I thought these were never installed!?

We see the attach points on this picture:

Image

I have checked on other pictures taken during STS125, and we can only see 2 attach points:

Image

Here as well, they are well visible:
Image

When they released it, we see the other side of the telescope, and I cannot see any attach points there:

Image

Pictures taken from : https://spaceflight.nasa.gov/gallery/images/shuttle/sts-125/ndxpage1.html
Last edited by eatdirt on Sun Jun 02, 2019 8:58 pm, edited 1 time in total.
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Re: Space Shuttle - Development

Postby legoboyvdlp » Sat Jun 01, 2019 8:45 pm

Not quite sure, that might be the boom that was apparently used to inspect the TPS after launch. Maybe it's stored over there when not in use?
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