Re-entry tutorial
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ar81
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[ame="http://www.orbithangar.com/searchid.php?ID=3428"]Tutorial: Concepts for atmospheric reentry[/ame]
jholley309
New member
Um...where the heck do you get the BaseSync MFD mentioned in the tutorial, or has that been incorporated into AreoBrake? No joy on Avsim or Orbithangar...
Jim
pattersoncr
Tutorial Publisher
ar81, I don't quite like the tutorial you've posted on OrbitHangar. It's too simplistic in my view: you don't get any control over the reentry profile once the deorbit burn is performed.
I prefer much more 'controllable' reentry: I frequently alter the bank angle and AOA to achieve the desired drag value and to divert some of the lift sideways. Reentry MFD is my best friend here, not the AeroBrake MFD.
This approach allows not exactly 'synchronising' the orbit with the desired base because the early S-turns may change the landing point by hundreds of kilometers. Actually, I suspect that I can reenter to virtually any base position without waiting more than one orbital period.
Nice pictures though, and a pleasure to read.
ar81
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I know it is too simplistic. It is my current way to do reentry...
As I learn more, I will make the tutorial bigger.
However, for those who get burned or bounce back to space, I am sure it will be useful.
As I learn more, I will make the tutorial bigger.
However, for those who get burned or bounce back to space, I am sure it will be useful.
Instead of starting a new thread, I'll chime in here.
I've used the autopilot on the DG-IV to re-enter after undocking from the ISS loads of times, and have figured out that making a de-orbit burn about 16.80M from the KSC works well for me, provided the re-entry angle is 1.2degrees. I got this from one of the DG-IV tutorials which said 1.2degrees re-entry angle with the de-orbit burn made 17.20M. After trial and error, I realised that 17.20M was too early if I wanted to be able to re-enter and make it to the KSC without running out of fuel.
But yesterday, I just launched into orbit using the autopilot and decided to re-enter after only one orbit. As usual, I performed the de-orbit burn 16.80M away from the KSC and made it so that the re-entry angle would be 1.2degrees. However, this time, by the time the re-entry autopilot had finished its thing and I was at about 25-30Km in altitude, I had barely made it over the West coast of the USA.
So two questions:
1.) Can anybody tell me why I didn't end up nearer the KSC as I usually do? Is it something to do with the height of the orbit? Because usually I de-orbit after visiting the ISS, but this time I didn't have the same orbital values as the ISS.
2.) Is there a method to working out how far out you should perform a de-orbit burn, without having to download and install extra MFD's?
Sorry for the long post
Thanks for any help.
I've used the autopilot on the DG-IV to re-enter after undocking from the ISS loads of times, and have figured out that making a de-orbit burn about 16.80M from the KSC works well for me, provided the re-entry angle is 1.2degrees. I got this from one of the DG-IV tutorials which said 1.2degrees re-entry angle with the de-orbit burn made 17.20M. After trial and error, I realised that 17.20M was too early if I wanted to be able to re-enter and make it to the KSC without running out of fuel.
But yesterday, I just launched into orbit using the autopilot and decided to re-enter after only one orbit. As usual, I performed the de-orbit burn 16.80M away from the KSC and made it so that the re-entry angle would be 1.2degrees. However, this time, by the time the re-entry autopilot had finished its thing and I was at about 25-30Km in altitude, I had barely made it over the West coast of the USA.
So two questions:
1.) Can anybody tell me why I didn't end up nearer the KSC as I usually do? Is it something to do with the height of the orbit? Because usually I de-orbit after visiting the ISS, but this time I didn't have the same orbital values as the ISS.
2.) Is there a method to working out how far out you should perform a de-orbit burn, without having to download and install extra MFD's?
Sorry for the long post
Thanks for any help.
joeybigO
can't get in a word edgewise
Pandadude
I like the name btw.
The de-orbit burn should be 180 degrees out of where you want to be. example: the KSC is -80.567 your burn should be 100.567 or 0 APD/PED.
There is a mathematical equation you can perform, however use the law of thumbs here, 180 degrees out put the PED to 0 and descend on the Spherical glideslope. Which there should be markers on the DG. Otherwise figure the descent rate by dividing total distance by speed, however you will speed up getting to the atmosphere. about a 28-35 degree angle helps me to land and about a 16m/s delta and you will be very close.
I used to use this inference about toast, but today I will use cookies, because I like cookies more than toast.
If you want the cookies to be done fast, high temp but for low time, but that makes for the cookies to be smushy on the inside. To do the cookies right it should be medium temp for a medium amount of time. Same principle applies to re-entry. Low temp and low angle makes for skip out, smushy cookies, but too steep and you have burnt cookies, and burnt astronaut cookies.
I hope this helps.
I like the name btw.
The de-orbit burn should be 180 degrees out of where you want to be. example: the KSC is -80.567 your burn should be 100.567 or 0 APD/PED.
There is a mathematical equation you can perform, however use the law of thumbs here, 180 degrees out put the PED to 0 and descend on the Spherical glideslope. Which there should be markers on the DG. Otherwise figure the descent rate by dividing total distance by speed, however you will speed up getting to the atmosphere. about a 28-35 degree angle helps me to land and about a 16m/s delta and you will be very close.
I used to use this inference about toast, but today I will use cookies, because I like cookies more than toast.
If you want the cookies to be done fast, high temp but for low time, but that makes for the cookies to be smushy on the inside. To do the cookies right it should be medium temp for a medium amount of time. Same principle applies to re-entry. Low temp and low angle makes for skip out, smushy cookies, but too steep and you have burnt cookies, and burnt astronaut cookies.
I hope this helps.
ar81
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Deorbit in the opposite side of the planet. It is in my tutorial.
If you do deorbit later, your entry anglee will be more steep and depending on how steep it is you might burn.
I also recommend to have an orbit as low as possible when deorbiting.
You will be trading altitude for speed and you do not want too much velocity when aerobraking, for it means higher temperatures.
If you do deorbit later, your entry anglee will be more steep and depending on how steep it is you might burn.
I also recommend to have an orbit as low as possible when deorbiting.
You will be trading altitude for speed and you do not want too much velocity when aerobraking, for it means higher temperatures.
orwellkid
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I must say I'm a recent convert to the AeroBrake MFD philosophy. Now that I understand what it's showing me.
I particularly like that can you make minor adjustments to your AOA and it calculates on the fly where you're gonna end up.
After 6 years of Orbiter with sketchtacular results upon reentry, I'm finally returning to Canaveral reliably like a hero.
All in all... it works well for me.
Cheers.
_O.K._
I particularly like that can you make minor adjustments to your AOA and it calculates on the fly where you're gonna end up.
After 6 years of Orbiter with sketchtacular results upon reentry, I'm finally returning to Canaveral reliably like a hero.
All in all... it works well for me.
Cheers.
_O.K._
astrosammy
Dash!
Capsules hmmmm.... I always land hundreds of kilometers from my target with them 
.
.ar81
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Capsules hmmmm.... I always land hundreds of kilometers from my target with them
Who cares, aircraft carriers can also travel a lot to find the capsule.
tblaxland
O-F Administrator
Theoretically 70% chance of hitting water for any random orbit (water to surface area ratio). Looking at a map, I'd guess your chances are probably better in a low inclination orbit.
70% sounds good enough to me
If I had been in charge back in the 60's, I would have let my team spend more time having fun that calculating where Mercury capsules were going to land. 70% of them landing in water anyway.
If I had been in charge back in the 60's, I would have let my team spend more time having fun that calculating where Mercury capsules were going to land. 70% of them landing in water anyway.
I will keep cookies in mind when I try again tomorrow!
Thanks for the advice both of you
Just to say thanks for the help, I gave it another shot using SyncBase MFD and Aerobrake MFD, and it worked a charm.
Came down right on top of KSC, nearly didn't even have to use engines to line up with the runway, and this was my first go.
Hopefully next time I'll be more prepared.
Oh and thanks to ar81, that tutorial was really useful.
Kveldulf
New member
I've been reading the info in here, but I'm having similar problems to Pandadude. I've used the AeroBreak MFD to help do the de-orbit burn 180 degrees away from the base (as mentioned in ar81's tutorial), but I've been having problems getting the right altitude to engage the DGIV's re-entry autopilot that would place me in the correct location at the right time. Anyone have any advice on that, or am I better off using the AeroBreak MFD's AoA hold?
What part don't you get about enabling the autopilot?
I think it can just be engaged at any time, it just means you can only fast forward time by x10. I'd leave it until about 150km altitude then engage it, then just do time x10 until around 90km when the autopilot automatically goes back down to normal time speed.
If that makes sense.
I get the impression you're saying you don't know what AoA to tell the autopilot to hold?
I'm no authority on the matter having only done re-entry successfully using the AeroBrake MFD once, but Id say start at about 35degrees, then see where the AeroBrake MFD says you will end up in relation to the base.
If you going too far, increase AoA for a while, then go back to 35 degrees until it is nearer the base. Just play around with it.
My way works, but is a bit fiddly, I'm sure theres a beter way of doing it, but maybe my way will help you for now.
Hope that helped in some way.
I think it can just be engaged at any time, it just means you can only fast forward time by x10. I'd leave it until about 150km altitude then engage it, then just do time x10 until around 90km when the autopilot automatically goes back down to normal time speed.
If that makes sense.
I get the impression you're saying you don't know what AoA to tell the autopilot to hold?
I'm no authority on the matter having only done re-entry successfully using the AeroBrake MFD once, but Id say start at about 35degrees, then see where the AeroBrake MFD says you will end up in relation to the base.
If you going too far, increase AoA for a while, then go back to 35 degrees until it is nearer the base. Just play around with it.
My way works, but is a bit fiddly, I'm sure theres a beter way of doing it, but maybe my way will help you for now.
Hope that helped in some way.
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