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Old Mar 08, 2010, 06:00 PM
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I need some advice about using bombs and rockets

Hey guys and girls
im going to mount some (dummy) bombs and sidewiders on my foam f16 and i would like to be able to drop those bombs and launch those misiles
so first of al where can i buy scale bombs and rockets ?(i don't know the exact scale but my wing span is a little over 50 cm so they cant be to big) or is there any way to diy them(i have tried casting them out of epoxy but they came out to heavy and not detailed enouf)

Where can i buy smal enouf rocket motor (bottle rockets that don't explode and who have enouf power)

what about launch rails, how can build light rails that insure a straight launch

and now the electrical part of the build
i would use 1 chanel to drop both bombs and launch both rockets at the same time i would use and extra batery and a relais and use electro magnets to mount the bombs (so when i flip the switch, the current stops powering the electro magnets and start powering the glow wires)
but what can i use to power the relais either a speedcontroler or a mosfet(hobby king sells them) but where do they sell lipo safe brushed speed controlers and how does that mosfet work( its needs a commen ground so the neg pole of the relais and the mosfet have to be the same but is that before or afther the bec (6 or 11 volt)?
or can i hook a relais up to the circuit board of a servo?

What about the electro magnets, how much current and volts does it need, how many coild would i need to make it strong enouf to hold the bombs in flight?
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Old Mar 11, 2010, 12:42 PM
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Sounds cool, I would love to see pics and vid!

Where are you located? I am pretty sure firing rockets (even fireworks) off of a remote controlled airplane would not go well with your local law enforcement. And I know that it is very much frowned upon by the AMA.

Bombs are great though, fill them with powder and let 'em drop!

Keep me posted on your progress!
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Old Mar 11, 2010, 07:11 PM
Nice, but watch this... oops.
Northern Ohio
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Hmmm......

This is a tough one. The bombs are ok, and fun to play with, but the rockets are just a bad idea. You'll never have accuracy enough from a moving plane to launch a rocket or missile safely. Plus this type of behavior gives the rest of us a bad name. Thus I won't advise you on that one.

Plus think about it, your basically shooting a projectile (read: bullet) from your radio controlled plane. It's just a bad idea. Plus how would you retrieve a errant round?

Bombs can be fun. As can parachute's, candy drops (for the kids) and water balloons on a hot day.

Your over thinking the release system tho. Electro magnets will draw too much power, and just be tooooo heavy to use. Instead use a system something like a tiny eye bolt or drinking straw on the bomb. Next use a servo on the plane. attach a wire to the servo horn, and run the wire out to your ordinance. next run the wire through two other eye bolts, or drinking straws that are mounted to the wing. The hook, loop, straw whatever on the bomb will be placed between the two hooks, eyes, straws on the wing and activate the servo so the wire passes through all 3 of them. next set the channel on your radio so when you activate the drop, the servo only pulls the wire back far enough so it clears the outer hook, and the hook on the ordinance, thus allowing it to fall.

This type of system only uses power to activate the servo, and will allow you to carry more weigh, as all the weight of the object being dropped is supported on the wire, and the hooks on the wing.

Hope this helps. Just google RC BOMB DROP there's tons of articles and videos of this type of system being used.

Bill
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Old Mar 12, 2010, 05:46 PM
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i live in belgium and fly in an official field
it was actually the owner of the club who challenged me to do it
its not illegal to fire fireworks from a rc plane and i consider inert sidewinders to be safer than firework rockets
the only reason i want to build this "weapon system" is as a proof of concept (i will probably take out the system afterwards for weight reasons

i didn't want to use a servo to drop the bombs because of the weight but now that i think about it i can use one central servo that uses fishing line to pull out both retaining pins (at first i tought i had to use 2 servo (one in each wing) and use metal wire from the servo to the bomb)

can i hook up a relays in parallel with the servo motor so once the motor starts turning the igniter will start glowing

does anyone know where i can buy 1/16 scale bombs and sidewinders ?
and how can i mount the rockets to my wingtips
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Old Mar 16, 2010, 04:45 PM
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hey guys
i have made some progress in my project
im going to make my rockets out of round balsa that i will lathe into shape and use those 6mm rocket motors they use for small model rockets

and as a ignition i soldered a relays onto the electronics of an old servo
i just have another small question do i need to solder a resistor between the 2 poles of the relays (does it work like a mosfet where you need e bypass in order to make it open after it has been closed )
to connect the igniter to the relays i'm going to use the carbon rods inside the wing just to save weight
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Old Mar 19, 2010, 09:22 PM
Micro Man!
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Be careful with the rockets, they could really disturb the flight when being shot.

For bombs, hobby king has a cool one.

MF
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Old Mar 20, 2010, 08:55 PM
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those hobby king ones are to big and not the right type
i doute that a minimax rocket will influence the flight path of such a big plane (compared to the rocket) i think i figured out a good rail system that should insure a clean launch
ill keep you informed on my progress

anyway my switch is almost finished it still has a small glitch (its always on because the relays doesn't care witch direction the current runs) but a diode will solve this

now im designing the sidewinders (or an equivalent rocket that can be mounted in the wing tip of a f16) does anyone know where the cg of a rocket should be
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Old Mar 21, 2010, 12:03 PM
Micro Man!
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Alright, but just keep it in mind when doing it the first time. depends on the plane i guess.

MF
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Old Mar 21, 2010, 12:24 PM
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I dont know anything about CG of rockets; but would love to see some pics of the progress!

What plane are you putting this set up on?
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Old Mar 22, 2010, 12:50 PM
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its a foam f16
http://www.rcgroups.com/forums/showthread.php?t=380552

its almost finished but the first plane won't be equipped with rockets (im probably going to crash on the first flight but im already building a second one who will have the mounting points and wires mounted inside the wing
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Old Mar 22, 2010, 03:56 PM
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looks like a neat plane, look forward to seeing yours soon!
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Old Mar 27, 2010, 04:20 PM
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project update
the electronics are done i tested the detonators and they worked like clockwork
i have build one sidewinder, rocksim says that it won't fly straight but i beg to differ
i will test them tomorrow
here are some pictures



i still have a small problem that 9volt battery doesn't make that glow wire glow fast enough (it doesn't provide allot of amps) could a capacitor solve that problem
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Old Apr 12, 2010, 03:56 PM
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update
it works like a charm i pushed the button the rocket ignited it cleared the rail perfectly
the rocket was a little bit unstable and didn't fly straight but my next rocket will be lighter and have a cg more to the front that should make it more stable

i replaced that 9volt battery with a 3.7 volt Lipo and it worked better
now im still tweaking the system to make it as light as possible
could i replace that variable resistance with a regular resistor?
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Old Apr 25, 2010, 01:22 PM
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I would say that if you worked out the optimum resistance of the variable resistor and replaced it with a fixed resistor of the same value then that would work the same probably
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Old May 04, 2010, 03:25 PM
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for better flight performance of the rocket remove the front fins, yes I know they look cool like a sidewinder missle but don't do much for stability.
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