[Alexw95]

can you do a free return with the dgiv ?

[Tommy]

It's a bit harder to do the inverted re-entry in a DGIV since it doesn't have COG shifting, but it's possible. If you don't mind a LONG re-entry, you can do it with a low AoA using just elevator trim. When coming in from the Moon or Mars, you will want a PeA of 70k to 75k so that your VS reaches zero before you burn up.

Also, the DGIV is actually very forgiving if you know few basic facts. Coming in from LEO (ISS altitude or less) you will NOT burn up until you are under 65k alt (even if well over the 19 ton "limit"). As long as you have the VS low enough, by 65k, you can re-enter a DGIV even fully loaded and fueled - you just need to have a lower descent rate under 65k to balance out the slower decelleration. This is also true for the XR vessels. I haven't done a lot of testing with the 2010 vesion, but from the bit of testing I have done, there isn't really much difference with the atmosphere model under 100k alt and everything works the same below that.

A DGIV with no cargo and very little fuel can be de-orbited as close as 6M from the target base, at a ReA of 6.75 degrees (PeA about 1000k below the surface if coming from the ISS) if you do it right (initial AoA of 20 degrees until VS reaches -50 m/s, then transition to a higher AoA and maintain about -80 m/s after that)

The main thing is to keep the descent rate at 80m/s or less (you may need to reduce this to 40 m/s if trying re-enter very "heavy") once you are below 65k altitude (assuming you are using a high AoA of 35 to 45 degrees). Keep the VACC low - NEVER more than 5 m/s. You don't have direct control over the VS, only the VACC, so keep in mind that any change to your AoA will take some time to affect your VS. You need to make changes to the AoA before you are in trouble, and keep the changes small (never reduce AoA more than 5 degrees at a time. Keep in mind that the faster you are decellerating the faster you can lose altitude, and visa versa. Also, it's best to de-orbit too early rather than too late - it's easy to extend the glide, and very difficult to shorten it without burning up.