For boosters that are about the same length as a foam parasite glider, I understand that it's more stable to have a balanced number of gliders symetrical around the core as in the old 'Space Twins' plans. But for a single parasite glider like the Orbital Transport, how long does the core need be to keep a fairly straight boost? I've put a foam shuttle on a Mean Machine with no problem, but that's too long to scale down. I want to put one of those little foam delta wings such as come with the Flisk Tri-Glide on to a small booster. I put two on a 13mm Gnome that worked, but what design would loft just one?
"...zere are zum zings man vass not meant to know."
Are you talking about just having the glider alone act as fins, or have the glider on one side and a number of fins on the other to balance things out?
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
Last edited by georgegassaway; 30th April 2009 at 02:42 AM.
Contest flying, Sport flying, it's all good.....
NAR# 18723 NAR.org
My website is BACK, at: GeorgesRockets.com
Safety FIRST, not Third......
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- George Gassaway
<"The glider is “free” to move around somewhat on boost>"
It's been known to happen.....take a closer look here.....
We got two categories of pilots around here. We got your prime pilots that get all the hot planes, and we got your pud-knockers who DREAM about getting the hot planes.
Now what are you two pud-knockers gonna have?... Huh?”
Pancho Barnes- The Right Stuff
George (Edited not Bob), I saw your Robarts UFO Gliders, after I had ordered a pair and an F117. I built a larger booster that is 29mm, 2.6in by 6ft. I left the UFO's Free Flight, and RC'd the F117. I have flown it may times dual UFO, and twice with the UFO/F117 combo, with good straight flights, but as you said on the OT above, I built the Booster with a box fin, so it would be stable by itself. I have photos of the Dual UFO, but none of the combo flight.
Last edited by mikeyd; 30th April 2009 at 06:51 PM.
Bob, I saw your Robarts UFO Gliders, after I had ordered a pair and an F117. I built a larger booster that is 29mm, 2.6in by 6ft. I left the UFO's Free Flight, and RC'd the F117. I have flown it may times dual UFO, and twice with the UFO/F117 combo, with good straight flights.....
Wow. The "Sci-Fi glider" I mentioned was the Robart "UFO" Glider, as was the F-117. I did not think anyone here would even remember those Robart gliders (I SO wish they had come out with the shuttle orbiter as they had planned for the next year. It would have been around 1/60 scale).
Anyway, my try at the F-117 on one side and UFO on the other side is what nearly crashed. Maybe it was a difference in the angle of attack.
And this is why I said at the start that there is no "clean" answer to this, I was shocked that bird nearly crashed, then it turns out yours flew fine, yet we have very similar boosters. Well, the F-117 / UFO prototype had a BT-60 based booster, but the F25 "afterburn" inside roasted the BT-60 so I made a BT-70 based booster when I did the two UFO gliders.
Below, the F-117/ UFO prototype, then the twin UFO version.
And a composite pic showing how the three hooks were done, glued to 1/64" plywood plates epoxied to the foam (if the hooks had been glued directly to the foam, they would have peeled off too easily). The carrier rocket had 3/16" launch lugs to match the 3/16" dowel hooks of the gliders.
- George Gassaway
Contest flying, Sport flying, it's all good.....
NAR# 18723 NAR.org
My website is BACK, at: GeorgesRockets.com
Safety FIRST, not Third......
I used a Robart UFO and the pod from an Edmonds Arcie II in order to cobble together an entry for an E BG contest a while back.
That was an 18 - 24" piece of BT-50 that mounted at the high point of the "cockpit" area of the glider. Boost was acceptable as I recall, but it did sort of arc and roll a bit.
George, I am such a ditz, sorry I said Bob, but it was your UFO's that prompted me to build mine. I used a wooden dowel on the booster, and mounted a single BT at the front of each glider to go over the dowel. I used a 2 wire "Guides" at the bottom to "Hold" each glider close to the booster. Your mounts look a lot cleaner than mine!
This forum always brings back such cool memories ....
When I was a kid, I used to buy little foam gliders that were delta-wing shaped and designed to be launched with a rubber band. They were about 3 or four inches long and cost, I think, about a quarter.
I used to glue a short piece of a wood dowel into the tab where you were supposed to hook the rubber band. On the rocket I'd attach a short length or two of launch lug tub just above the fins. I'd hang one or two of the little gliders on the small launch lugs so that they just touched the fins.
At apogee, the little gliders would separate and glide down. My usual carrier for them was my Omega which I actually launched using a C motor most of the time (because D motors seemed too big and scary!).
At the time, I thought I'd invented the idea of using them as parasite gliders. :-)
I haven't seen the same type of gliders any stores since then. I've seen a few about the same size, but they were made of plastic and a different kind of foam.
I have a couple of the bigger Guillow shuttle gliders. I didn't think of it until now, but I could hang them on my upscale Omega ......
When I was a kid, I used to buy little foam gliders that were delta-wing shaped and designed to be launched with a rubber band. They were about 3 or four inches long and cost, I think, about a quarter.
............
I haven't seen the same type of gliders any stores since then. I've seen a few about the same size, but they were made of plastic and a different kind of foam.
THat glider was from "North Pacific" long ago. They sold to Guillow's a few years back.
At NARAM-46, someone [edit update - Kevin Johnson] did an "Imagination Celebration" flight that had, I think, FORTY of those little gliders on it [edit update - 24 gliders on it]. It boosted up, arced over, and no ejection yet, it was coming down,down, down and at about 60-70 feet up it ejected at high speed and "Whoomph" the sky was FULL of little gliders, and it won the event.
Hey, I just found pics of it on Chris Taylor's archive of NARAMlive for NARAM-46. Kevin J, I see you in both pics, was this yours? It used a Super Big Bertha to carry them up
I have done a few off and on. I converted an old (normal size) Big Bertha to carry as many as 4 of them.
North Pacific had another great foam glider. A shuttle orbiter. Guillows brought it back, here is one place that has it:
Hey, I just found pics of it on Chris Taylor's archive of NARAMlive for NARAM-46. Kevin J, I see you in both pics, was this yours? It used a Super Big Bertha to carry them up
- George Gassaway
Yeah, that was my Super Big Bertha. There were 24 glidersattached to it, and thebonus delay from the E15-4 caused the more dramatic ejection.
Only Jim Flis would have the cajones to give a glider kit a name that almost sounds like it means "try to glide". I have seen an awful lot of "try to glide" kits over the years, that often didn't. Take the Crusader swing-wing, please (Bad-ump-ump!).
But if those foam gliders do not glide, it ain't the fault of Jim's kit....
- George Gassaway
Contest flying, Sport flying, it's all good.....
NAR# 18723 NAR.org
My website is BACK, at: GeorgesRockets.com
Safety FIRST, not Third......
I'm looking to make a CHAD 1/2A BG entry. I've got the little delta foam gliders which can be trimmed well with some modeling clay. Adding a roll tab on the booster sounds good, but it may not matter on such a small motor.
"...zere are zum zings man vass not meant to know."
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Originally Posted by georgegassaway
