There is not a really clean answer to this. Realize that even the Orbital Transport has a relatively long booster core.
Do take note that the O.T. booster is stable all by itself. It can fly without the glider. The glider is “free” to move around somewhat on boost, since that nose hook is the only thing holding it on. If you wanted to do a design where the glider added to the stability you yowled have to have it secured in 3 places (like the space shuttle orbiter to the ET) so it could not pry off in pitch or yaw or roll.
I am even a bit surprised that the O.T. does not have a pitching problem.
One thing I would suggest is that you rig the fins to make the booster roll, so that if the glider does try to make the whole bird pitch, it will do a wide barrel roll on boost instead of tying to pitch to horizontal (and maybe pitch into the ground).
Sometimes these things can be very sensitive. I once tried a twin glider project using a Foam Sci-Fi type glider on one side, and a foam F-117 fighter on the other side. They were the same basic size, so I thought they would be “balanced”. But it tithed very badly to one side. It would have crashed hard if not for just so happening to roll SLOWLY on boost, so it got horizontal then rolled 180 and then pulled back towards vertical (mostly) to avoid disaster. I never tried that again. I dumped the F-117 and added an identical Sci-Fi glider on the other side, and painted it orange so it could be distinguished from the other one (both were R/C rudder-only, so there needed to be a way to tell them apart).
I will suggest that if this was going to be a special project that was going to be sort of “big”, to build a VERY crude small-scale version first and test it out. If it has problems, tweak on the test model till it is flying well, then build the real project that way. Or even if it is not to be a big project, still, it may be worth making a crude test model first, rather than put a lot of time and care into the assembly and finish on a model that mght have fatal flaw.
I did that with my “Orbital SkyDart Project. I had already made a 2X scale-up Estes SkyDart, with R/C, in 1999. In 2004, I built a winged booster (SkyBooster) to carry it up piggyback, then ignite the engine in the SkyDart to “stage” it. I was not sure about the pitch stability, and also wanted it to be able to glide with the SkyDart on its back in case the staging failed. So, I built a 1/3 scale crude test model (BT-20 for the SkyDart, BT-50 for the SkyBooster).
Pics below show the 2X SkyDart with the 1/3 scale test models, test model together, test model boosting, and the final model before flight (Bob Parks on right). Bonus: the 1/3 scale test bird made for a nice little sport flying model itself.
- George Gassaway
