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BLG - Ballistically Launched Glider: A new project/build thread

earthsciteach

Moderator
Moderator
#41
There is no easy way to use the mixed foam for my purpose. In the end, it would be equally as effective and far easier to carve xps foam to match the glider. I'd hate to have to pick the glider out of expanding foam that formed itself around the thing.

I still contend that a lightweight build combined with structure that is in line with the force of the launch will do just fine.
 

rcspaceflight

creator of virtual planes
#45
Funny thing is I almost said that you could use it for mushrooms in a stop motion Super Mario Brothers video if it didn't work for your sabot...
I once saw a bad Japanese monster movie where they used expanding foam to show mushrooms quickly grow. Just saying.
 

rcspaceflight

creator of virtual planes
#46
earthsciteach, I like your idea of using the sabot as padding to help soften the force exerted onto the glider. But I wonder if you need a full sabot. You really only need a plug behind the glider to make the cannon airtight. Maybe make some sort of dolly that holds the glider firmly to a plug. Maybe just have two sticks/shafts coming out of a plug to hold the glider to it. And then make the plug out of a soft foam, something compressible. The soft foam will compress to absorb some of the impact of the air/explosion but still push the glider out with full? force. Once the glider and dolly/plug come out of the tube, then the two sticks can either fold back away from the glider, or just let the glider slide out. I'm thinking one stick on each side of the fuselage of your glider to hold it firmly in place. But you'll probably need the sticks bolted down tight to the fuselage in some way so the force is spread through out the fuselage and so the force isn't all exerted onto the tail. With a sabot, the force will probably still be all on the tail of your glider, depending on how strong the sabot is. A hard sabot with a soft back will work great, it just seems like a lot of work. A soft plug with a hard point to mount two arrow shafts on just seems a lot easier.
 

Tritium

Amateur Extra Class K5TWM
#49
The Estes design with its hollow tube fuse would lend itself quite well to an "Over Tube" launch instead of an "In Tube" launch.

Thurmond
 

earthsciteach

Moderator
Moderator
#50
I thought about the scissor wing concept, but am fearful that, if deployed at too high a speed, the forward portion of the wing would be damaged. Plus, it will necessitate a longer sabot.

I am pursuing the full sabot idea because it will carry more momentum and have less drag than the glider alone would. I'm trying to deploy the glider as high as possible.

The pod is carved to shape. I now have to hollow out the electronics bay and cut the rear of the pod to receive the CF tube (fishing rod blank).
 

earthsciteach

Moderator
Moderator
#53
Ah, I follow you, Rob.

My current track is for the sabot casing to keep the wings in place. When released, the sabot breaks apart (pushed by the deploying wings) and a glider is born.
 

Foam Addict

Squirrel member
#54
Teach,
What if you were to build and fiber glass a circular tail cover similar to a bomb with a main circular outer fin the same diameter as your cannon, but with 90 degree fins inside for control. Then you could build a simple sabot that would fit behind the fins, but would blow off right after launch.
 
#55
Typical muzzle velocity from a spud gun is on the order of 300 MPH. It will be quite difficult to design a stab that can withstand those aerodynamic forces. Furthermore, if the stab is deployed immediately after launch, it will have to be completely neutral to avoid a death spiral. Keeping the glider fully protected in a sabot/fairing until apogee is far and away the best way to go.
 

Foam Addict

Squirrel member
#56
Umm, sorry, I'm not very clear. Imagine a circle with two lines crossing at 90 degrees at the center. Then imagine that that is the tail of the aircraft. True, I just thought I would share the idea.:)
 

earthsciteach

Moderator
Moderator
#57
Foam - that's a good idea. I worked on a study YEARS ago to modify a land based tactical missile for launch from an, um, alternate platform. Your idea was similar to part of the solution, there.