SRB gliders. Runway to orbit and back.

[Galane]

Some SRB gliders I've been experimenting with.

glider-landed-0 by g_alan_e, on Flickr

The classic SRB with wings and wheels. Stable under thrust in atmo until going fast enough to heat up. Needs constant pitch up correction while gliding.

glider-landed-1 by g_alan_e, on Flickr

The new SRB. Had to use a pair of dropping wings at the back to be stable under thrust, dropped to be stable gliding. Had problems getting it off the runway, this one scraped its booster off but had enough altitude and up pitch for MechJeb to keep it under control on the way up. Landing was a bit of a miss.

glider-landed-2 by g_alan_e, on Flickr

Success. I put a huge pair of wings on the front to pry it off the runway. Also put wheels under the booster to protect it. Front wing drop was manually staged, had to time it right. Too late and it would pitch over backwards and slam into the runway. Too early and it'd pitch over forwards and slam into the runway - despite the COL shifting behind the COM after dropping the front wings, which should have made convert to stable rocket flight. Once high enough it would rocket on up OK but had a period where it would pitch up too much before coming back - resulting in losing some downrange distance.

Getting off the runway was much easier with the old SRB, sets at enough up angle it has next to no takeoff roll and Ascent Guidance takes it up... sometimes.

Can you make a glider with all solid fueled rockets that can get to orbit, (these probably could with manual flying) any sort of orbit with a periapsis at least 70KM, then return to KSC runway for a deadstick landing? These can't do the return, they have no deorbit capability yet, still working on the whole taking off and landing without blowing up thing...

You may have noticed the radial mount parachutes. They're attempts at recovering from spins, stalls and dropping straight down backwards. Dunno how they get into that situation and why they won't come out of it automatically even with the chute - when they will glide straight as long as they don't stall.

What I've noticed is that control surfaces behind the COL lift up when you want to climb. This in front of the COL drop down. I presume it's to rotate the plane about the COL in flight. Problem is when attempting to take off from the runway all control surfaces except the ones at the very back should go down to pick the plane up. What I get with these ships is all the controls behind the COL moving up and keeping the thing pinned to the runway.

This could be corrected by a check to see if the plane has lifted off yet, if not, control surface movement behind COL should be inverted to increase all lift to get the plane up.

Another way to correct it, without having to change the game program, is a flap control surface that can only move in one direction and has a top and bottom - and is setup so that when oriented top up and behind COL it will move down when the plane is commanded to pitch up. It should also be action groupable to disable and return to neutral position.

I see why canard designs work so well in KSP since all wing surfaces have vertical lift all the time. Real canard design aircraft are more efficient because the main wings don't have to fight against the rear stabilizer's downforce.

The traditional forward wing lifting and rear stabilizer pushing down to counteract the slightly forward COM isn't modeled properly. There needs to be some liftless fins to take the part of flat or symmetrical aerofoil horizontal stabilizers, or a way to individually tweak the force strength and direction of wings and fins.

Edited May 11, 2014 by Galane