Help my paratroopers- Looking for ideas for rotation mechanics
08-10-2007, 05:32 PM
#26
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RE: Help my paratroopers- Looking for ideas for rotation mechanics
I havent built it, just a concept. I would probably make my own spring on my lathe. The geared motor would be one of these - http://www.pololu.com/products/gearbox.html
Havent really thought of where you could get a spring off the shelf. I was thinking of something in the 3/4" to 1" dia. Will need to look around and see whats available. The chute would have to be wrapped in such a way that it would be untied as its spit out. That would give it enough time to get clear then open up.
Edwin
Havent really thought of where you could get a spring off the shelf. I was thinking of something in the 3/4" to 1" dia. Will need to look around and see whats available. The chute would have to be wrapped in such a way that it would be untied as its spit out. That would give it enough time to get clear then open up.
Edwin
08-10-2007, 07:05 PM
#27
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RE: Help my paratroopers- Looking for ideas for rotation mechanics
ORIGINAL: VFR_RC
The problem with this is that the drum won't have momentum but friction resistance. on a train the momentum of the car keeps the wheels moving thus pushing it through the longest point in the revolution and then back again.
ORIGINAL: da Rock
If the cranks are the same length, this orientation should cause the driven crank to follow the driver crank. The start orientation, with the cranks pointing to 0degrees, should be as easy to set initially as your drum is going to be. The cranks should start in the desired direction and as long as the drum has momentum, would follow through a full rotation. There is a problem that makes the choice of wheels or sprockets much more reliable. When the cranks reach 90degrees and 270degrees, the driven crank will have only slight force on it. The driven crank will be pulled in the right direction as the driver crank rotates through 90/270 however. The problem would be if you tried to start cranking with the cranks pointing 90/270.
Wheels sound like the best choice.
Is your blocked off trooper cavity there to act as a door? Have you solved the problem of how to line that closed cavity up to the door? If you have, then the crank orientation would be no problem.
BTW, this has been a kick. Thanks for sharing the fun. Can't wait to see the airplane.
If the cranks are the same length, this orientation should cause the driven crank to follow the driver crank. The start orientation, with the cranks pointing to 0degrees, should be as easy to set initially as your drum is going to be. The cranks should start in the desired direction and as long as the drum has momentum, would follow through a full rotation. There is a problem that makes the choice of wheels or sprockets much more reliable. When the cranks reach 90degrees and 270degrees, the driven crank will have only slight force on it. The driven crank will be pulled in the right direction as the driver crank rotates through 90/270 however. The problem would be if you tried to start cranking with the cranks pointing 90/270.
Wheels sound like the best choice.
Is your blocked off trooper cavity there to act as a door? Have you solved the problem of how to line that closed cavity up to the door? If you have, then the crank orientation would be no problem.
BTW, this has been a kick. Thanks for sharing the fun. Can't wait to see the airplane.
And that's why I mentioned that the wheels were the best choice. Although, there is a method to support the pushrod that uses the crank to provide a 90degree motion that would solve that problem. The problem with it is the complexity. And truth is, until the drum method was shown to have a positive means of ejecting each trooper from his cubbyhole, driving methods weren't really of much significance.
08-10-2007, 10:45 PM
#28
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RE: Help my paratroopers- Looking for ideas for rotation mechanics
ORIGINAL: Edwin
Interesting concepts here. I've also been looking at how to drop paratroopers serially. I havent actually tested this so its just speculation at the moment. I was thinking of a box about 1 1/4" square and about 10" or so long with a slot, see attached. Have a spring in the box turned by a gear reduced motor. You load the paratroopers by running the spring backwards. When it time to jump, run the spring forward. Clear as mud.
Edwin
Interesting concepts here. I've also been looking at how to drop paratroopers serially. I havent actually tested this so its just speculation at the moment. I was thinking of a box about 1 1/4" square and about 10" or so long with a slot, see attached. Have a spring in the box turned by a gear reduced motor. You load the paratroopers by running the spring backwards. When it time to jump, run the spring forward. Clear as mud.
Edwin
08-11-2007, 09:30 AM
#29
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RE: Help my paratroopers- Looking for ideas for rotation mechanics
And wouldnt that be just too cool. <g> Would love to some artillery dropped out the back of an rc C-130. Then a gaggle of paratroopers out the back. Then a lotar menuver with a humvee on a pallot. Then have a 50cal pop up with a soldier behind it and drive it off the pallet. Good airshow event. <g>
Edwin
Edwin
08-11-2007, 10:51 AM
#30
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RE: Help my paratroopers- Looking for ideas for rotation mechanics
ORIGINAL: Edwin
And wouldnt that be just too cool. <g> Would love to some artillery dropped out the back of an rc C-130. Then a gaggle of paratroopers out the back. Then a lotar menuver with a humvee on a pallot. Then have a 50cal pop up with a soldier behind it and drive it off the pallet. Good airshow event. <g>
Edwin
And wouldnt that be just too cool. <g> Would love to some artillery dropped out the back of an rc C-130. Then a gaggle of paratroopers out the back. Then a lotar menuver with a humvee on a pallot. Then have a 50cal pop up with a soldier behind it and drive it off the pallet. Good airshow event. <g>
Edwin
Any portion of that would be cool at an R/C fly-in.
08-11-2007, 12:29 PM
#31
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RE: Help my paratroopers- Looking for ideas for rotation mechanics
For quite some time I've been planning on doing a test bed for all the C-130 mechanisms in the form of ugly stick style C-130. Probably in the 100" range. Gotta call it the HerkyStick. Sorry guys, I shouldnt hijack.
Edwin
Edwin
08-11-2007, 02:09 PM
#32
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RE: Help my paratroopers- Looking for ideas for rotation mechanics
I got a nice surprise from my mailman today. He brought me my gearing for the paratrooper launcher. It weighs less than 2oz. Its a pair of plastic gears, plastic chain, and an aluminum hub that mounts on my drum axle.
THis should work great.
Mike
THis should work great.
Mike
08-12-2007, 07:17 PM
#33
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RE: Help my paratroopers- Looking for ideas for rotation mechanics
ORIGINAL: khodges
Pope AFB / Fort Bragg (in NC) does (or did) this at its airshow, sort of. They sling-load a -105 under a Blackhawk, drop it on the field, and then another Blackhawk comes in and a bunch of guys fast-rope down and get the 105 in action. Then a 130 comes in and does a LAPES of a Humvee, and several more come in and dump a couple of sticks of troopers at about 500 feet. After that, a couple of C-141's drop more at higher altitude, they "take over" the airfield. Then the Blackhawk comes back and picks up the guys who fast-roped, they fly off hanging on the ropes. Pretty exciting for the crowds.
Pope AFB / Fort Bragg (in NC) does (or did) this at its airshow, sort of. They sling-load a -105 under a Blackhawk, drop it on the field, and then another Blackhawk comes in and a bunch of guys fast-rope down and get the 105 in action. Then a 130 comes in and does a LAPES of a Humvee, and several more come in and dump a couple of sticks of troopers at about 500 feet. After that, a couple of C-141's drop more at higher altitude, they "take over" the airfield. Then the Blackhawk comes back and picks up the guys who fast-roped, they fly off hanging on the ropes. Pretty exciting for the crowds.
Anyway, during my tour there i have done numerous jumps into andrews airforce base from Bragg as part of Military airshow. Nothing was in unison as khodges said but really close. Usually the heavydrops will be performed by the slow flying c-130's then hordes of paratroopers will jump out on the next 5-6 c-130s trailing usually halfhour away. We couldn't jump out of the faster flying c-141's in andrews. Which however is a much better experience then the c-130's. I did get two jumps out of C-5's which is REALLY not fun. Those planes have to fly almost 50-60 knotts faster and once you exit the door is like getting pushed out of a car and hitting a brickwall at 60mph.. It HURTS...
Sorry for my little story, this forum just brought back some good memories.
As for the current thread I thing the vending machine corkscrew idea is the better idea, but could be harder to build. I think that would promote less chances of hangups as there is, I think, a pretty large margin for error in the rotating drum idea.
08-12-2007, 07:25 PM
#34
RE: Help my paratroopers- Looking for ideas for rotation mechanics
You could put a ratchet from a ratche wrence between the gear and the top of your parachuetist can. That way the servo wouldtn't have to be modified to run continuously.
The servo would turn the can going one way, and the ratchet would slip when the servo went the other way. this way a simple on off switch on the transmitter would dump a jumper every time you flipped it.
The servo would turn the can going one way, and the ratchet would slip when the servo went the other way. this way a simple on off switch on the transmitter would dump a jumper every time you flipped it.
08-12-2007, 07:45 PM
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RE: Help my paratroopers- Looking for ideas for rotation mechanics
Tomski-
This had been suggested by a guy at my LHS. But for ease of jumper deployment, it was ruled out. I would hate to have to hit a switch for each jumper. The "vending machine" idea has the most promise for this type of deployment. My drum works great, but there is always one jumper that fails to jump. I attribute this to the lack of a shaking aircraft. If the rotating drum was being shook by a moving C-130, then all my jumpers would successfully egress.
For now, I am going to try both jumper deployment methods. I am waiting for some design pictures from a guy in Ohio on the inner workings of the "vending machine" type launcher. http://www.rcuvideos.com/item/LQ0BZ9M7VF22FNBC
Here was a simple test of my mechanics. One jumper needed some assistance to jump.
Mike
This had been suggested by a guy at my LHS. But for ease of jumper deployment, it was ruled out. I would hate to have to hit a switch for each jumper. The "vending machine" idea has the most promise for this type of deployment. My drum works great, but there is always one jumper that fails to jump. I attribute this to the lack of a shaking aircraft. If the rotating drum was being shook by a moving C-130, then all my jumpers would successfully egress.
For now, I am going to try both jumper deployment methods. I am waiting for some design pictures from a guy in Ohio on the inner workings of the "vending machine" type launcher. http://www.rcuvideos.com/item/LQ0BZ9M7VF22FNBC
Here was a simple test of my mechanics. One jumper needed some assistance to jump.
Mike
08-13-2007, 10:15 AM
#37
RE: Help my paratroopers- Looking for ideas for rotation mechanics
Loved the kick out the door!
How about a piece of foam behind each jumper to push them out?
I see why you like the continuous rotation, worked nicely, gave the appearance of proper spacing between the jumpers.
We've used the rotating coil to drop tickets from blimps in the past. The only drawback is the non driven end can only be supported by having it sit on something. thats why it works in a vending machine.
How about a piece of foam behind each jumper to push them out?
I see why you like the continuous rotation, worked nicely, gave the appearance of proper spacing between the jumpers.
We've used the rotating coil to drop tickets from blimps in the past. The only drawback is the non driven end can only be supported by having it sit on something. thats why it works in a vending machine.
