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Rocket motor / rocket RPG / whatever, get in here

TheGerman

Oberleutnant
Full Member
Minuteman
  • Jan 25, 2010
    10,608
    30,201
    the Westside
    What Estes rocket motor would someone need in order to propel a nerf football that has been cored to accept a PVC pipe down its center, riding on a steel cable, slightly downhill at about 50-60 yards at a decent rate of speed?

    Asking for a friend.
     
    About 50 years ago I could have answered this off the top of my head.
    I'm unable to find the weight of a Nerf Football, plus yours has a piece of PVC in it. What does your contraption weigh?
    The first thought I have is that those motors MIGHT be too fast to shoot at. Also, the fire..not sure if that matters.
     
    Coupled with a bag of black powder for the initial boom/smoke, you can simulate an RGP pretty well. Just wire the igniters together.
     
    So it looks like the common ones on amazon are

    Estes A8-3, B6-4, C6-5​


    Do these sound right as far as the models I can use to test? Or is there a better place/better versions?

    I know zero about this stuff.
     
    Burn time on the D12 is about 2 seconds, might still be burning at 50 yards, C11 is in between those, just under 1 sec burn time. Cheap enough to buy a pack of each and test before you stock up.
     
    • Like
    Reactions: maceface
    So it looks like the common ones on amazon are

    Estes A8-3, B6-4, C6-5​


    Do these sound right as far as the models I can use to test? Or is there a better place/better versions?

    I know zero about this stuff.
    Don't use the -X other that -0, that's the delay to the ejection/ignition charge. You want a booster engine, a -0 so it just burns out.
     
    The first number is burn time, the second number is the delay time to pop the shute. The ABC's are the size of the motor and thrust.
     
    If your simulator weighs 10 oz, a D12 should get you about 230 FPS per Sec, so still burning at the end of a 50 yard track. You can always use a multi engine core, 3 C11's would launch at 347 FPS/Sec, burn < 1 sec
     
    • Like
    Reactions: Sean the Nailer
    You have been given some fantastically accurate information. Run with it.

    FWIW, just in case you're interested, an "I" engine will lift a 4' 1x1 an easy 225' into the air, straight up. You have to make them yourself though.
     
    • Like
    Reactions: camocorvette
    I really think an A-series would be good for what you want to do. Also, in the case of the A8-3, depending on what effect you want, you would have a 3 second pause down at the end of the line and then the ejection charge. This may or may not fit into your desired assclownery. A-,B-, and C-series engines are about as big as a nickel; D-series between a quarter and half dollar. I wish I had a dollar for every rocket I lost in a corn field.
     
    For something like that you can probably use a C02 cartridge.
    *Should* be cheaper and easier to rig too.
     
    Going the exact opposite direction, instead of a rocket motor, you could use highly compressed air driving out a stream of slightly soapy water as the reaction mass. You can get a lot of thrust and all you have to do is pump the tank back up and fill up the water.
    It is of course easier to make a simple one when things are going up than down...
     
    This might work.

    RPG.jpg
     
    Use a small funnel or similar going into the front of the PVC pipe to guide it along the cable to reduce friction.
     
    • Like
    Reactions: stefan73
    Doing some simulated training, cool beans.

    Probably look at an E16-8 it has about 5.9lbs of max thrust for a fraction of a second. Total thrust duration is about 2 seconds.