Laythe Atmosphere Insertion with a Jet Aircraft

[Zosma Procyon 502]

What is the best way to bring a jet aircraft into Laythe's atmosphere safely? Should I dump as much velocity with rockets as possible before insertion, or dump just enough so my perigee is just above the ocean's surface? I've done the latter once before and it almost ended with a flat spin stall and crash; I managed to land safely some how.

[Aeroboi 351]

56 minutes ago, Zosma Procyon said:

What is the best way to bring a jet aircraft into Laythe's atmosphere safely? Should I dump as much velocity with rockets as possible before insertion, or dump just enough so my perigee is just above the ocean's surface? I've done the latter once before and it almost ended with a flat spin stall and crash; I managed to land safely some how.

The best way is to use Tylo as a gravity assist to lower Jool Apoapsis, if possible do it a 2nd time at laythe or again Tylo.
Space planes could be like the space shuttle is typically, use a pitch angle of 10-55degrees over the horizon once in the atmosphere. The high attitude angle will then decelerate the orbital speed in the upper atmosphere. If you design a space plane properly most of your parts will be 2400K resistant and the other parts are in cargo bays.

In that case I wouldn't worry about aerobraking issues at all and you should have no worries.

Edited May 6, 2019 by Aeroboi

[Zosma Procyon 502]

11 hours ago, Aeroboi said:

The best way is to use Tylo as a gravity assist to lower Jool Apoapsis, if possible do it a 2nd time at laythe or again Tylo.
Space planes could be like the space shuttle is typically, use a pitch angle of 10-55degrees over the horizon once in the atmosphere. The high attitude angle will then decelerate the orbital speed in the upper atmosphere. If you design a space plane properly most of your parts will be 2400K resistant and the other parts are in cargo bays.

In that case I wouldn't worry about aerobraking issues at all and you should have no worries.

I have a plane en route to Laythe right now, and it will arrive with enough leftover delta-v to stop dead over Laythe and maybe even land vertically. I just need to know how much velocity I should dump.

[bewing 3,055]

It depends on how long a glidepath through the atmosphere that you want. Often when I'm landing on laythe, I'm looking around for nice biomes and features as I glide for hundreds of km without reducing my reentry speed at all. With the intent of flaring heavily when I see a geologic formation that I like. Often that results in so much heat buildup that my poor little plane explodes. And then I promise myself not to do that again.

If you're not picky about your biome or landing spot, I think you could easily enter laythe's atmosphere at 2km/s -- just so long as you start aerobraking immediately. I wouldn't enter at anything faster than 2200m/s, I don't think. The atmosphere is too thin to trust it for a lot of drag.

[Brikoleur 4,016]

Laythe is one of the easiest bodies to land on aerodynamically. As @Aeroboi said, grav brake off Tylo and/or whatever other Jolian muns are available, then aerocapture, then enter. I don't recall exactly how much dV I expended the last time I did this but it was pretty low, maybe 200-300 m/s total from Jolian transfer orbit. Laythe is lower gravity than Kerbin so aerobraking is a lot gentler.

The trick is to get a good intercept of Laythe for aerocapture, i.e. nice and tangential to its orbit so that your relative velocity is as low as possible. And for aerocapture you can tune your orbit rather precisely by controlling your plane's attitude -- just point yourself prograde when the orbit has tightened enough for your taste.

Edited May 9, 2019 by Brikoleur