From: mckiou@cbnewse.cb.att.com (kevin.w.mckiou)
Subject: Shuttle Orbiter
Organization: AT&T
Date: Wed, 26 Aug 1992 18:14:05 GMT


I thought many people would enjoy reading about George Gassaway's shuttle
orbiter.  The attached is e-mail I received from him which he has given
me permission to post.  I edited-in a couple of explanatory comments
which are identified by "- Kevin".  A most interesting project with a
lot of history <G>.  

Kevin

------------------------------George Gassaway's Shuttle Orbiter------------

I've built a few shuttle orbiters over the years, including a few full stacks,
nearly all for sport, and few to even "look good". In '82 I built a 1/72 scale
R/C orbiter, based on Luther Hux's plans in Model Aviation. His plan differed
from scale in  few ways, notably in larger wing area, but it's not too bad. I
flew that a number of times, on D12/D12, and a few (4) times on F15. Only on 
the F15 did it ever get high enough than to simply set up to
land! Later, I made a 2nd R/C orbiter, scale wing area, with ET and
SRB's as a prototype for a potenital FAI scale team project (where there
would be a whole US team entering three shuttles). That project fell
apart, meanwhile the testing didn't go very well either. It did look
sorta neat, but at that size and mass it was underpoweered with an F15,
and FAI rules still do not allow over 80 N-sec! Even aside form that,
there were a number of nagging problems so I gave up on that. Full stck
shuttles can be done, definitely, but a 1/72 R/C full stack shuttle, a
really big PITA! 
  I took the original R/C orbiter out of mothballs in 1989 to fly at NARAM-31.
Then that fall the chute in the rear-eject carrier rocket stripped and the
whole thing plummeted, smashing the orbiter. I didn't figure it worth the
repair, especially having used my last F15 for that flight, and though G25's
could have done it, at $16-18 per flight it wasn't too enticing (F15's were
also around $15 then too!).
  I was hoping to build a 1/87 shuttle with ET & SRB's for the World Champs
next month. But realized in February it wasn't coming together well enough to
do it, so I had to punt and switch back to the Little Joe II for the scale
entry. But, I REALLY wanted to have some sort of shuttle model to FLY....
  Then Bob (Parks - Kevin) had the offer about the Raven-7
prototype. And coming with Raven-7 was the 32mm RC motor. ( Raven-7
prototype kits were put together and made available ($) to a few
experienced RCRG flyers - Kevin)  HMMM. A shuttle at $3-5 per
flight??!!! So, I got back to thinking about the R/C orbiter. But not to
fix the old one. I always wanted to make a bit bigger one, but it would
surely have needed a G25 per flight, and that was not practical since
something like this is worthy of flying more than once at a launch, and
more than say 3-4 times a year! The 32mm motors would allow that. So, I
scaled the 1/72 plan up by 25% dimensioinally, resulting in 56.25% more
area. 1/57.6 scale.  Now, in the old bird, a little over half the mass
was the bird, and the rest was R/C "paylaod". While the bigger bird would 
have more structure mass, the "payload" would be the same, resulting a
significantly lower wing loading than the old bird. Maybe I should say "guess
the glide mass", but for the old one it was about 7.5 ounces, for the new bird
it turned out to be about 10 ounces. Plus of course, being a bit bigger, the
Reynolds numbers get a bit better too.  The orbiter span is 18" and the
length is 22"
  Ah, fabrication. No, not a kit. This is purely for fun, and not practical to
make into a kit. It was built mostly like my others, nearly all-balsa.
Including a nose section more built-up than carved (except for the nose block).
The OMS pods and main engines are vac-formed though. Rudder plugs into the
fuselage so for transport it's a lot easier.
  Glide control is elevons for pith only, and real live rudder for turning. I
found out in the other birds, mostly flown with mixed elev/aileron in the
elevons, that it was too sensitive for my tastes. Esp as I was not an aileron
pilot before the shuttle! I did find that by making the LOWER half only of the
rudder move, that it would give very nice turning control on glide. But that
carries a nasty price, the rudder deflecting left to turn left in a gldie, will
result in a RIGHT roll on boost! ecause it then acts more like a vertical
aileron, than a yaw-inducer. So, my Tx is set up to mix rudder & aileron
sticks, I fly boost on the rudder stick REVERSED (left stick, right rudder),
then fly the glide on the aileron stick. Ah, yes, with a magic computer Tx I
could set it up to just flip one switch at transition to do tha,t but that's a
lot of $$ just for the orbiter, and I'm getting used to doing it this way. But
you'd have never thought it could get so bizarre, huh?
  The orbiter does not have the motor shoved in it, it does fly piggyback on a
very unusual carrier. The design of the carrier is based on a 3/8" square
spruce stick, 36" long. At the rear, the 32mm motor mount, and two ventral fins
angled apart eqach about 15-20 degrees from the ventral axis. Up front, several
ounces of lead noseweight. In between, the attachment points for the orbiter to
ride along the "top side" of the carrier. One of these points is near the CG
where there is a locking mechanism activated by R/C. Flush agaisnt the orbiter
belly are two pices of BT-55 cut lengthwise in half-shell fashion. These house
the parachutes. When the orbiter is released, the belly no longer holds the
chutes in the BT-55 shells, so the chutes fall out.
  Of coruse, it would be simpler to make up a big dumb normal rocket to carry
the orbiter up on, but the mass and drag of that would really hurt the
performance with the 32mm motor, maybe not even allow it to be practical. THe
liftoff mass of the whole combo is about 21 ounces, somewhat less than
Phoenix/R7, though not quite as clean. But it defintely gets about 400-500' on
the F13 and 800-1000' on the G12. At any rate, watching my old orbiter plummet
I vowed never to do this again without an R/C release, so I'd never go back to
the simple "fall off at chute ejection" method!
  Having said that, the 2nd flight of this new bird, the R/C sep failed, but it
managed to hit at about a 45 deg angle and was very fortunate to just get some
scrapes & dings, could easily have smashed the nose and/or broken a wing. I was
keying off the last bit of travel of feull up elevator, but there was too much
friciton that flight. Well, after that I put in a 3rd servo dedicated to the
R/C sep alone, and that sovled that (since I'm using a 4 channel Cannon micro
Rx, I can't use the landing gear switch on the tx for this, so I'm using the
throttle stick. So, this simple little "2-channel" orbiter end up using all 2
stick axes!).
The orbiter has now made 11 flights, 4 at NSL/NARAM. It's worked out as well as
I hoped, and sometimes it's just a dream to fly. The only nightmare of late
being possibly needing to dig up some sort of "Basement bomber's cookbook" if
reloads got stopped  long-term/forever! Really, being able to fly this bird to
400-500' for $3 and 800-1000' for $5 is what REALLY makes this work out well,
because it's not a money-guzzler that can only be flown a few times per year.
To think, what I used to fly the OLD orbiter with, staged D12's, cost more than
the F13 and lasted at best 2/3 as long (30 sec, sometimes 20 sec). Heck, the
G12's about the cost of two D12's for that matter, and it yields flights of
typically 75-90 seconds!

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