SandroSalgueiro
New member
Hello everyone,
I've been into Orbiter for 2 months now and have been practicing Shuttle reentries after acquiring quite a constant mission success ratio with the DGIV and XR-2. Today I bring you a theoretical question regarding the reentry process of the three quoted vessels that has been twisting my mind.
On my first DGIV reentries, I noticed in the AerobrakeMFD the following relation between AoA and Range when the former was a value between 10 and 60: the greater the AoA (roll 0), the smaller the range and vice-versa. Because of this, every time the impact point was beyond my desired target, for instance, I rose the nose and killed some additional energy before returning the AoA to the standard 40 deg, now with the impact point aiming on the landing site -- just like a glideslope correction.
When I switched to the XR2, I noticed this procedure remained exactly the same, and I had no hard time adapting to the new craft.
As I'm getting started on the Shuttle, I noticed, however, that things are different. On my first reentry tries and while trying to execute the same procedure, I noticed that, unlike in the XR2 and the DGIV, a gain in AoA (roll 0) increases the range instead of lowering it, thus creating the necessity for S-turns.
After evaluating these situations, I couldn't come up with a full explanation on why the reentry procedure on these 3 winged vessels differ (S-turns aren't needed in the DGIV and XR2, for example). Is it about L/D ratio? Weight? Why doesn't the XR2/DGIV bounce back into orbit at an AoA of 40 deg and 0 roll?
Please notice that these conclusions regarding AoA and Range relations were all taken by mere visualization of the AerobrakeMFD at approximately 100K altitude.
Thank you for your attention so far.
I've been into Orbiter for 2 months now and have been practicing Shuttle reentries after acquiring quite a constant mission success ratio with the DGIV and XR-2. Today I bring you a theoretical question regarding the reentry process of the three quoted vessels that has been twisting my mind.
On my first DGIV reentries, I noticed in the AerobrakeMFD the following relation between AoA and Range when the former was a value between 10 and 60: the greater the AoA (roll 0), the smaller the range and vice-versa. Because of this, every time the impact point was beyond my desired target, for instance, I rose the nose and killed some additional energy before returning the AoA to the standard 40 deg, now with the impact point aiming on the landing site -- just like a glideslope correction.
When I switched to the XR2, I noticed this procedure remained exactly the same, and I had no hard time adapting to the new craft.
As I'm getting started on the Shuttle, I noticed, however, that things are different. On my first reentry tries and while trying to execute the same procedure, I noticed that, unlike in the XR2 and the DGIV, a gain in AoA (roll 0) increases the range instead of lowering it, thus creating the necessity for S-turns.
After evaluating these situations, I couldn't come up with a full explanation on why the reentry procedure on these 3 winged vessels differ (S-turns aren't needed in the DGIV and XR2, for example). Is it about L/D ratio? Weight? Why doesn't the XR2/DGIV bounce back into orbit at an AoA of 40 deg and 0 roll?
Please notice that these conclusions regarding AoA and Range relations were all taken by mere visualization of the AerobrakeMFD at approximately 100K altitude.
Thank you for your attention so far.
