- Joined
- Jan 17, 2009
- Messages
- 5,204
- Reaction score
- 1,547
At the local “Dollar Tree”, I found some blow-molded plastic crayons. They are about 24.5” long and about 2.5” OD in the areas that bulge out. The mass of the original Crayon is 90 grams, or about 3.2 ounces.
Maybe this particular Crayon has been converted before, by somebody.
I do not think I will get around to converting one to fly for awhile, so I wanted to mention it now while these are “out there”, as these seem like great ones to convert to fly. And the price is sure good, $1. Of course, YMMV may vary as to whether your local Dollar Tree has any.
The back of the crayon has a black flexible plastic insert. Well, pop out the insert, and the remaining hole is a PERFECT fit for the Quest 30mm diameter tube. Now, yes, one could convert this to fly on 29mm engines. What I am looking to do, eventually, is convert it to fly on a D12 (maybe C6), so I’ll put a 24mm engine mount inside of the 30mm tube. The great thing is that there is no need to cut a perfectly centered hole, it already exists. And a 30mm tube would be useful as both a stuffer tube and as a tube to glue the fins to. So, at least the back end of the Crayon will center the tube, a custom centering ring will have to be made up to center the upper end of the 30mm tube (or a ring to hold the 30mm tube in a BT-70).
The one bit of actual “building” I did, well, it was not building but disassembly. I cut the upper part to make it into a nose cone. Later on, that nose cone will get a shoulder, and probably a bulkhead since there is a slot in the tip for coins (Ah, yes, I did not mention this is supposed to be a “piggy bank”, which is also why it has the removable plug in the base). The inside diameter of the plastic is about 2.25”. A BT-70 fits almost PERFECTLY inside of it, it would only require a few wraps of tape to get it to center right. Now, a BT-70 tube would add some mass, but would be justified if it was flown on E or above composite engines since the ejection charges tend to be pretty hot and such (Afterburn of Composites). For a model that only used a D12 (or E9), well, it might be OK to have the 30mm tube run about 8” or so up inside of the crayon, as the ejection heat past that distance (and the distance of the 30mm tube sticking out the back) probably would be cooled enough not to melt the plastic.
Now, for stability, I’m not going to mess around with clear fins. They are nice, but a PITA. I want this project to be a nice simple easy to build, and not-too-fragile thing. So, I am going to have the 30mm tube stick out of the back by 4 to 6 inches. Then glue some wood fins on it, such as 1/8” hard balsa for a “light” one to fly on C or D power, or 1/8” “lite” Plywood for one that flew on 29mm E, F, or G power. Then mask off the whole crayon and paint the 30mm tube and fins flat black.
With the above, maybe someone will beat me to actually building and flying one.
- George Gassaway
Maybe this particular Crayon has been converted before, by somebody.
I do not think I will get around to converting one to fly for awhile, so I wanted to mention it now while these are “out there”, as these seem like great ones to convert to fly. And the price is sure good, $1. Of course, YMMV may vary as to whether your local Dollar Tree has any.
The back of the crayon has a black flexible plastic insert. Well, pop out the insert, and the remaining hole is a PERFECT fit for the Quest 30mm diameter tube. Now, yes, one could convert this to fly on 29mm engines. What I am looking to do, eventually, is convert it to fly on a D12 (maybe C6), so I’ll put a 24mm engine mount inside of the 30mm tube. The great thing is that there is no need to cut a perfectly centered hole, it already exists. And a 30mm tube would be useful as both a stuffer tube and as a tube to glue the fins to. So, at least the back end of the Crayon will center the tube, a custom centering ring will have to be made up to center the upper end of the 30mm tube (or a ring to hold the 30mm tube in a BT-70).
The one bit of actual “building” I did, well, it was not building but disassembly. I cut the upper part to make it into a nose cone. Later on, that nose cone will get a shoulder, and probably a bulkhead since there is a slot in the tip for coins (Ah, yes, I did not mention this is supposed to be a “piggy bank”, which is also why it has the removable plug in the base). The inside diameter of the plastic is about 2.25”. A BT-70 fits almost PERFECTLY inside of it, it would only require a few wraps of tape to get it to center right. Now, a BT-70 tube would add some mass, but would be justified if it was flown on E or above composite engines since the ejection charges tend to be pretty hot and such (Afterburn of Composites). For a model that only used a D12 (or E9), well, it might be OK to have the 30mm tube run about 8” or so up inside of the crayon, as the ejection heat past that distance (and the distance of the 30mm tube sticking out the back) probably would be cooled enough not to melt the plastic.
Now, for stability, I’m not going to mess around with clear fins. They are nice, but a PITA. I want this project to be a nice simple easy to build, and not-too-fragile thing. So, I am going to have the 30mm tube stick out of the back by 4 to 6 inches. Then glue some wood fins on it, such as 1/8” hard balsa for a “light” one to fly on C or D power, or 1/8” “lite” Plywood for one that flew on 29mm E, F, or G power. Then mask off the whole crayon and paint the 30mm tube and fins flat black.
With the above, maybe someone will beat me to actually building and flying one.
- George Gassaway
Last edited:
