Rocket Powered Balsa Glider

[EeebeeE]

I work for an ad agency and we are doing a promotion that involves a dime store balsa glider like the one pictured below.



I have been asked to make one rocket powered. I would rather leave the motor tube attached to the glider as opposed to having it separate. I would use motor ejection as the recovery system. Below is my design from power point. Think it will work?

 

[TheAviator]

Do you want it to fly like a rocket or like an airplane. Or both?

If you want it to fly like a rocket, just put a long (~9") pod on it and recover with a streamer. That would work just fine.

If you want it to fly as an airplane, boosting in horizontal flight, I wouldn't recommend it. The motor is too powerful and level flight under rocket thrust is dangerous.

If you want it to go up as a rocket and come down as an airplane, then a pop pod or a slide pod is a necessity.

 

[JeromeK99]

Honestly, I think those 1/32" paper thin wings are going to snap right off.

Jerome

 

[BEAR]

I have done something similar several decades ago when I was a teenager. I used bottle rockets for propulsion. IN this case, I think I would use a 1/4 or 1/2A "T" motors, and practice a few times before showing the gliders off. You could also build the glider in RockSim or Open Rocket first and see how it launches for location of the motor pod. I know it can be done because I have 3 gliders in my files currently and it has proven accurate. I would start with my pod being a bit ahead of the center of gravity and make sure the center of pressure is several calibers behind the center of gravity. Again, do it in RockSim, or Open Rocket first to see how it fly's for the launch. It may not be completely accurate, but could give you a good idea. I think I would also re-enforce the leading edges of the wings and tail surfaces with Scotch tape. I would also make my motor pod long, with a motor block in place. This way you will have room for a streamer attached to the motor. I would use a small amount of tape to help to lightly hold the motor in place, then it ejects. I used to take a safety pin and cut the two legs back, at a sharp angle, then I bend a 90 degree about an 1/8" long at the end of each leg,so that I can use the spring to secure this in the ejection charge end of the motor. Then I can attach a streamer to this so the spent casing can be recovered and watched on the way down. Good luck, and I hope this helps. BEAR

 

[shreadvector]

As depicted, it will crash and burn (and possibly start a fire). The lift from the wing and the moment created by the rocket motor way down low will add and make the rocket glider pull up and fly in a big loop or loops until crashing into someone, something or the ground.

Look at the Estes Classic Collection for basic boost-glider design info.

You might want to use a Quest MicroMaxx II-NE motor. Short powered flight, but it will not rip it to shreds and fire is minimized. But you still need a stable design......

I work for an ad agency and we are doing a promotion that involves a dime store balsa glider like the one pictured below.

View attachment 130442

I have been asked to make one rocket powered. I would rather leave the motor tube attached to the glider as opposed to having it separate. I would use motor ejection as the recovery system. Below is my design from power point. Think it will work?

View attachment 130458

 

[closet astronaut]

I'm seeing alot of naysayers here but it could be done. There's a guy here on the forum by the name of Astron Mike, I had a launch day with him once and he brought his gliders. As stated by TheAviator about the wings coming off, I thought the same thing when I saw mikes gliders, they were made from paper, and I don't mean cardboard, I mean paper, the wings were very thin fiber board and he was launching with D-12's. The whole trick here is elevator control, his were spring loaded, the engine ejected from the rear, like the mount for a regular engine only as long as the body tube, the whole thing ejected. As it ejected it would pull the paper clips that held the elevators flat and level, he could tune the elevators to tighten the circling. He also used quarters taped in the nose cone for balast. When I first saw his stuff, initially I wasn't impressed....untill he started launching them, then I was blown away.

Here is a video I made for him of the flights..

[YOUTUBE]dZwOu6Um-pw[/YOUTUBE]

You would have to make sure the wings are flat and strait, then have some part of the tail fins hinged so they would work like the elevators on a regular plane.

 

[EeebeeE]

The forward wings rise about 5 degrees from the center of the fuselage. The rear stabilizer is canted about 2.5 degrees or so to create lift under glide. Did a quick OR on it and with a 1/4A it flies to about 55'. An A10 will put it up to about 200'. OR isn't set up to do glide recovery (or I don't know how to do it) but with motor the CP is 1.25" aft of the CG. I think a motor eject can work.

 

[BEAR]

If you look for the drawings to the Estes Falcon boost glider from the 60's, you will see that it is an airplane with the rudder/vertical stabilizer on the bottom of the body/ keel. The wings have about 20 degrees of dihedral. The horizontal stabilizer/elevator has about 2 degrees of up. The motor ejects and the glider goes into glide mode. IIRC, back in the 60's, this glider fell out of favor because NAR rules would not allow you to eject a motor without a recovery device on it, hence the reason I made the comments about a longer tube earlier. I think your rocket powered glider is very similar. (Yes, different, but much the same.) You might also look at the pod on the Nighthawk glider by Estes and the old BumbleBee glider with ejectable pod. If you can incorporate some of that into your glider, you might have an easier conversion. Good luck, I think it can be done.

 

[shreadvector]

Read the simple advice I already provided. If you put the motor under the wing you will have MASSIVE pitch up and a looping crash.

 

[Gus]

You are way better off turning your gliders into boost gliders instead of rocket gliders. As rocket gliders they have 4 major problems.

First problem is that if you make this a rocket glider, like in your picture, your will need to position your motor pod so that the glider balances the same before and after you glue the empty pod in place. If you want your glider to glide after the motor ejects, the glider's center of gravity should be the same as it is without a pod. For gliding, most gliders will have a center of gravity just behind the forward edge of the wing. A motor pod as shown in your picture is so far forward there is no way the glider will glide properly (it will be so nose heavy that it will just nosedive to the ground). But if you glue a pod just beneath the wings, at the center of gravity, it will add weight and make something as light as your dime-store-type glider glide poorly.

Second problem, as Fred and other's also mentioned, is that if you place the motor pod at a proper balance point for glide, the glider will develop lift throughout the motor thrust and will just loop over backwards and crash into the ground under thrust. The only way to keep that from happening is to give it a counteracting force in the tail, which is very complicated to do on a dime-store-type glider.

Third problem of turning this into a rocket glider is that spitting engines isn't really a very good idea. Yes, a lot of the very early glider designs use it, as to some tumble recovery rockets, but it's inelegant at best and a hazard at worse.

Final problem is that Dime-store-type gliders aren't very robust. Even if you turn them into parasite gliders you will need to beef them up a bit by supergluing the wings and tail in place.

So if you want to rocket boost these gliders, you are way better off turning them into parasite gliders and launch two at a time, one on either side of a booster rocket. All you need to do is put a little hook on each of two gliders (put your hook at the center of gravity point). Then build a simple booster with 4 fins and a nosecone (13 or 18 mm sized) and streamer ejection. Put two launch lugs on opposite sides of your booster for your glider hooks to sit into, and you're good to go.

The Estes Shuttle Xpress, or the Squirrel Works Dogfight are good examples of these kinds of parasite gliders.

Good luck.

 

[EeebeeE]

This is what it turned out to be. Test throws show it has minimal lift, but flies fast. I think if it launches at 20 degrees it will nose straight up, do a loop after motor ejection, then return to earth with a good steady and fast glide. Everything is epoxied into place and I will use cellophane tape on leading edges. The CG without the motor is about 1/4" aft of the leading edge of the wing. With the motor it is almost in the same spot because the motor extends 3/8" aft of the tube.

Thanks for all who are concerned about this crashing and catching fire although I do believe that feeling is a little melodramatic. We've had a lot of rain lately and if the fins rip off it should still have the stability of a bottle rocket. Plus, the first flight is with a 1/2 A motor.



Estes did design rocket gliders with motor ejection several years ago so there is precedent that this should work.

 

[shreadvector]

FALCON motor is on top. your motor is on the bottom.


I have said this many times already and you refuse to comprehend it: the motor on the bottom will pitch the nose UP and any lift on the wing will pitch the nose UP and any downward lift from the horizontal stabilizer will pitch the nose UP.


UP + UP + UP = looping crash.

This is what it turned out to be. Test throws show it has minimal lift, but flies fast. I think if it launches at 20 degrees it will nose straight up, do a loop after motor ejection, then return to earth with a good steady and fast glide. Everything is epoxied into place and I will use cellophane tape on leading edges. The CG without the motor is about 1/4" aft of the leading edge of the wing. With the motor it is almost in the same spot because the motor extends 3/8" aft of the tube.

Thanks for all who are concerned about this crashing and catching fire although I do believe that feeling is a little melodramatic. We've had a lot of rain lately and if the fins rip off it should still have the stability of a bottle rocket. Plus, the first flight is with a 1/2 A motor.

View attachment 130532

Estes did design rocket gliders with motor ejection several years ago so there is precedent that this should work.

View attachment 130533

 

[EeebeeE]

I have said this many times already and you refuse to comprehend it

Dude, I get it. I really do.

Chill out a little, OK? We are talking about something powered by a 1/2A motor...4.5 foot-ounces of thrust. But if you want, I'll call the fire department, make sure an ambulance is standing by, and secure an FAA waiver. Does that make you feel better?

Estes also made a kit that had the motor on the bottom and was powered by 18mm motors. They marketed it as a quick-build kit that could be assembled and in the air within 1/2 hour. Can't remember the name.

If you set the lift on the rear stabilizer right it would do a loop under power and eject the motor at about 50' above the ground, rise back up to about 200', then gently land. It was made out of cardboard for the wings and a balsa framework. I used to fly it in a field next to my dad's house and had a ton of fun with it. No one ever got hurt and nothing burned.

Geez. Get a life!

 

[BEAR]

Evan, I was thinking that if you made the motor pod removable like on a NightHawk or The Sky Dart, you could cant it enough that you could fly straight in boost (I know that on my 2.3X Falcon I canted the ejectable motor mount from inside the main motor tube by 6 degrees) You could then mount it on the bottom of the body and with a 1/2" tall stand off, with one-side of the stand-off having the 6 degree or whatever you decide is good, and with the ejection and removing of the pod, your glider would certainly glide further without the weight and drag, would eliminate some balance issues, and more easily correct any arc-overs. Since you are a L-2, you are not a novice, you have a good idea of what you are doing. Again, good luck.

 

[EeebeeE]

Not a bad idea, Bear. I might do that if we decide to go with the foam glider at a later date, although a 4' wingspan foam glider probably would need a separate motor pod.

The whole purpose of this was for a viral marketing video and it would get video views whether the flight was successful or not (I am a media director at an advertising agency). I was stuck with the confines of flying this particular type of glider. The motor tube was mounted to the bottom because it was flat and parallel to the cantor of the wing. I am surprised at how balanced it came out, but I had done some OR sims so I was able to work with the physics in the design a little more instead of just slapping a motor on it and calling it a day.

I had the choice of doing this or the foam and decided to do this one because it was smaller and would be more manageable to fly in the park we intend to fly it in.

Also for grins, I had though about upscaling the glider sans motor to an 8' wingspan using plywood for wings and stabilizers, and a sheet of pine for the fuselage. I reasoned that if I cut a wing-shaped slot for the 3/16" sheet of ply that I have that the bend would give it enough stiffness to the wing. I might still try that sometime. Don't know how I would throw it.

 

[BEAR]

"Don't know how I would throw it. "

You could do it like some do with their R/C sailplanes, they use a long piece of surgical rubber tubing, stretch it out to about 300' and let go of the glider. It is called a "High Start". You can purchase them already to go. It is a little more complicated than that, but I am sure you get the idea.

 

[RWmarlow]

Just to find out....glued a motor tube to A guillow's Jetfire and "launched" it on a Quest A6-4 it did a nice almost ground loop... pitched back up stalled and fell to the ground in time for the delay to finish burning....funny but that was about it....An Estes Tuff Bird ( Thanks secret santa)flew quite well as a parasite though

 

[EeebeeE]

Just to find out....glued a motor tube to A guillow's Jetfire and "launched" it on a Quest A6-4 it did a nice almost ground loop... pitched back up stalled and fell to the ground in time for the delay to finish burning....funny but that was about it....An Estes Tuff Bird ( Thanks secret santa)flew quite well as a parasite though

If this does the same our mission will be accomplished.:wink:

 

[RoyAtl]

I would go with a parasite glider arrangement if possible. I know it won't be quite as "kewl" as a motor directly on the glider, but it will be much more successful.

See Page 26 of this issue of the fabled old Model Rocketry Magazine for how to do it: https://www.ninfinger.org/rockets/ModelRocketry/Model_Rocketry_v03n02_11-70.pdf

 

[BEAR]

As a side note, in that issues of Model Rocket Magazine, the NARAM was held at the Manned Spacecraft Center in Houston. My NAR section (Apollo-NASA) hosted the event. On page 24, the photo at the bottom, although not mentioning my name, only Ben Russell's name; I am the kid on the right. Those two rockets flying the drag race were mine. I had a Flight Systems F-100 in mine, Ben's had a new Enerjet motor in the one he was launching. Those rockets, in comparison to what was normally flown, were huge. They normally were great crowd pleasers due to their size. Just thought I would throw this in, since I was there.

 

[gdjsky01]

As another side note: Comparing the OP to AstronMike is not fair to AstronMike who has spent years experimenting with what does and does not work. I know what is being said is, "Think outside the box". And I applaud that. :clap: But the keyword there is of course 'Think'.

I owned AstronMike's kits back 10 or 12 years ago when he kitted the Maxi-Marauder and Novus-D as well as his saucer tri-pack. Most of AMs big designs are ejecting pods that change the CG and actuate surfaces.

Anyways: Good luck on your designs.


PS: Fred's advice may be blunt, but worth hearing since he's been doing this stuff since... oh... the 70's? I know, Argument from antiquity. But still...

 

[RWmarlow]

I would go with a parasite glider arrangement if possible. I know it won't be quite as "kewl" as a motor directly on the glider, but it will be much more successful.

See Page 26 of this issue of the fabled old Model Rocketry Magazine for how to do it: https://www.ninfinger.org/rockets/ModelRocketry/Model_Rocketry_v03n02_11-70.pdf

Thanks Roy! Loved that issue...and back then In a college town in Ga various brands of parasite gliders were out there... Plaza 5&10 had North Pacific, Add's Rexall had Testors, Golden Pantry Had Guillows and Hodgsons had Pactra

 

[EeebeeE]

Fred's advice may be blunt, but worth hearing since he's been doing this stuff since... oh... the 70's? I know, Argument from antiquity. But still...

I respect that Jeff, but we're supposed to be having fun with this hobby. Also for the record, the first rocket I flew was in 1970.

A parasite is probably the better way to go in most cases, but there were reasons beyond experiments with rocket designs for doing this configuration. I've also seen some of the newer weight-shift gliders that look like they'd be fun to try.

 

[TheAviator]

Dude, I get it. I really do.

Chill out a little, OK? We are talking about something powered by a 1/2A motor...4.5 foot-ounces of thrust. But if you want, I'll call the fire department, make sure an ambulance is standing by, and secure an FAA waiver. Does that make you feel better?

Estes also made a kit that had the motor on the bottom and was powered by 18mm motors. They marketed it as a quick-build kit that could be assembled and in the air within 1/2 hour. Can't remember the name.

If you set the lift on the rear stabilizer right it would do a loop under power and eject the motor at about 50' above the ground, rise back up to about 200', then gently land. It was made out of cardboard for the wings and a balsa framework. I used to fly it in a field next to my dad's house and had a ton of fun with it. No one ever got hurt and nothing burned.

Geez. Get a life!

And the kid that got severely hurt a few years ago was only flying an A motor. The last thing this hobby needs is a viral video with someone getting hurt with a rocket. There are enough people who do experiments like this on youtube to see what the results are.

That being said, if you must do it this way, please at least practice some wider stand-off distances. Something on the order of 50-100 feet.

 

[EeebeeE]

@Aviator,

Rest-assured, all safety precautions will be taken, and the last thing our client needs is a viral video in which someone gets hurt. As I mentioned earlier, I've been doing this since 1970. We will practice all safety guidelines. The launcher I will use for this is a specially-made launcher for cluster rockets. It has 8 d-cell batteries and 75' of speaker wire.

I hope the first person who launched his/her rocket to 20,000' got this same sort of scrutiny.

A K motor will launch a cinder block up to 1,000'. A 1/2 A motor will just piss the cinder block off.

 

[TheAviator]

Sounds good, let us know how it goes.

 

[majordude]

Read the simple advice I already provided. If you put the motor under the wing you will have MASSIVE pitch up and a looping crash.

Yep!

I have said this many times already and you refuse to comprehend it: the motor on the bottom will pitch the nose UP and any lift on the wing will pitch the nose UP and any downward lift from the horizontal stabilizer will pitch the nose UP. UP + UP + UP = looping crash.

Double yep!

And someone else was right too, unless this a 1/4 A, this will likely shred even if you listen to shreadvector's advice.

 

[EeebeeE]

Thanks to all of you naysayers for your splendid advice. I do think there is a little melodrama in your choice of words. Even if a small glider with less than a 12" wingspan weighing less than half an ounce, powered by a 1/2 A motor were to crash, I would hardly categorize such an event as "MASSIVE." If safety precautions are taken, the better description might be "FUNNY."

Let me summarize all the points that have been brought up
- As for a loop, I think that will happen, although I do not see it diving into the ground. The thrust will come from under the wing, but the motor is almost completely forward of it.
- Leading edges of wings and stabilizers have been covered with cellophane tape. That will provide some protection. The OR sims I ran showed the top speed with a 1/2A motor is only about 70MPH, though which is not much faster than if it were hand-thrown.
- 5-minute epoxy was used for construction so it is solidly assembled.
- The CG is 1/4" aft of the leading edge of the wing. the CP is 1/4" forward of the trailing edge of the wing.
- When hand-thrown HARD there is no porpoising effect at all. That suggests that it may not pull up as hard as one might think.

But if you read all that was written you would rightly conclude that the build is complete. At this point, any further construction advice is irrelevant. This was a fun little 10-minute project. That's all. If it flies well, great. If it crashes, it will be a good laugh. Lighten up everyone!

 

[RWmarlow]

A Jetfie (which is the same as the promo glider) didn't shred on a Quest A6-4...when the pod was cut off and the glider given away it was must less durable in the hands of a five year old

 

[gdjsky01]

Evan I think everyone is saying the same thing. Just some with more gusto than others. No one is against experimentation. Just like you said, no one wants that viral video of a little girl or boy getting hit, even if its a flea.

Good luck. And of course, be safe.