Flight Question What is the cross range for DGIV?

[769270865]

I just reenter DGIV from ISS to wideawake with about 500Km off plane distance,and I did the deorbit burn little late.during the reentry i bank to the left around 70 to get over off plane distance but around 50KM ALT the nose first over heated. I try to reduce bank and rise AOA, than seconds after DGIV destroyed.
Does 500KM is too much? DGIV said my reenter angle is only 0.8 with a max G 4.8.

The DGIV was the one released December last year.

 

[SolarLiner]

500km at closest approach is way too much. For any spaceplace. You may have waited one orbit to bring it down to ~100km.
With my own experience with the DGIV, I think any closest approach over 50km is too bad to be taken as reentry window.
But remember that you can burn Normal/Antinormal to bring your closest approach down (with BaseSync it is extremely easy).
Then you have to not reenter too shallow, or you'll burn in the atmosphere, turning you into pieces. You may search for "DGIV Reentry" in OF to get the values to enter in BaseSync / IMFD to get a reentry profile.

 

[garyw]

500km at closest approach is way too much. For any spaceplace. You may have waited one orbit to bring it down to ~100km.

Real life shuttle had over 1,000km of cross-range but they never got anywhere near that. One trick that NASA did was a re-entry burn where not all of the energy went into lowering the orbit - some was used to reduce the cross range.

Personally, with the DG-IV I always end up with far too much prop so I use some of it to reduce the cross range to 10KM or so then dump most of the rest of the prop and then re-enter.

 

[RisingFury]

Cross range for the DGIV is in the 100 km max, even with 100 km, you struggle. At 40° AOA, the expected Lift to Drag ratio should be close to 1. Instead it's at close to 0. That means you have very very little lift.

The best you can do is decrease AOA to 30° and increase bank to as far as it'll safely go, but determining where the safe limit is through the worst of the reentry is difficult. I've lost many DGIVs experimenting that away...

If you wanna reenter with the DGIV, use BaseSyncMFD and make sure your trajectory passes within 100 km of the base.

 

[statickid]

Alternatively, since it IS the DGIV, you probably have quite a load of fuel left, you can adjust crossrange with high altitude mach 3-4 cruising with very little engine power.

---------- Post added at 10:03 AM ---------- Previous post was at 09:51 AM ----------

However, if you have enough fuel for that, then the crossrange should eliminated while in orbit. In the DGIV I usually keep some fuel for minor over and under shooting.

 

[Tommy]

Actually, the DG-IV has plenty of cross range. I've made re-entries with around 7000 km and more. The "trick" there is to use a fairly low AoA (15 degrees) and allow for a longer distance covered during the aerobrake.

 

[N_Molson]

The DG-IV can easily glide thousands of kilometers in the very high atmosphere (40-60 km). Just keep the angles soft.

 

[Urwumpe]

One trick that NASA did was a re-entry burn where not all of the energy went into lowering the orbit - some was used to reduce the cross range.

But that wasn't done for reducing cross range, but rather for trimming the spacecraft properly for reentry by "wasting fuel" in the aft tanks. With a full tank and all cross-feeds, the shuttle could only change the inclination by 2° or about 200 km cross range (less if you also need fuel for deorbit).

Still you had maximal 1500 km cross range. But that cross range is only available for some distances past entry interface, you can't reach every base that is 1500 km away from the initial ground track. The more energy you pull away for gaining cross range, the less downrange you have. And if you need a short downrange, you also can't turn all energy into cross range safely.

 

[csanders]

IIRC, I've launched a DG-IV into a polar orbit from KSC, and landed back at KSC with 1 orbit.