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reciever effecincy vs. Rocket speed ????

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Old 04-03-2004, 04:36 AM
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C 130
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Default reciever effecincy vs. Rocket speed ????

hello guys : ) hope you are all fine.
i had a strange question in mind... well what if i had my RC system installed on my Model rocket for some reason.... would the very high speed of my rocket affect the reception of the RC signal or are we still in the safe zone ????
thanx guys ))
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Old 04-03-2004, 08:12 AM
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Default RE: reciever effecincy vs. Rocket speed ????

how fast is your rocket? there are 250+ mph jets that use our stuff...in fact, i'd bet the reception would be better at high speeds because the reciever is bombarded with more magic radio dust than at low speeds
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Old 04-03-2004, 08:42 AM
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ALbert.S
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Default RE: reciever effecincy vs. Rocket speed ????

You will only run into trouble when your rocket exceeds the speed of light.
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Old 04-03-2004, 04:39 PM
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Default RE: reciever effecincy vs. Rocket speed ????

Actually, it might pay to check the law but if you're in the USA I believe that radio-controled rockets are illegal. Something to do with anti-terror laws :-(

I doubt that Egypt has such laws however :-)
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Old 04-03-2004, 06:02 PM
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Default RE: reciever effecincy vs. Rocket speed ????

what are you going to control? a servo on the fins makes for a VERY short flight... (don't ask...) servos tend to hunt very small amounts, and this can translate into flutter very quickly at rocket speeds. not to mention since a rocket will never track perfectly straight, you have no idea which way is up, and therefore controls on the fins are basically useless...
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Old 04-03-2004, 09:17 PM
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Default RE: reciever effecincy vs. Rocket speed ????

You will only run into trouble when your rocket exceeds the speed of light.
That's probably not true. Doppler frequency shift (due to the relative velocity between the Tx and the Rx) would cause the receiver to lose lock far before the speed of light was reached.

John
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Old 04-04-2004, 12:44 AM
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Default RE: reciever effecincy vs. Rocket speed ????

It depends on the speed and also on the G forces. Servos have been used for years on radio controlled rocket gliders with no problems and these are not illegal in the US. The reception will be fine but the servos may have trouble under a high G load.
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Old 04-04-2004, 02:24 AM
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Default RE: reciever effecincy vs. Rocket speed ????

hello guys
we couple of ideas rose here ) one about high speed and doupler effect, i guess just for curiousity i will try to check my Relativity chapter here
the other very interesting point here IS
that servos would not work if used for controlling fins ????? why wouldnt it ???
we have two points of view:
1) causeitflies-RCU SAID:

ORIGINAL: causeitflies-RCU

It depends on the speed and also on the G forces. Servos have been used for years on radio controlled rocket gliders with no problems and these are not illegal in the US. The reception will be fine but the servos may have trouble under a high G load.
and we have
2) rkramer SAID
"what are you going to control? a servo on the fins makes for a VERY short flight... (don't ask...) servos tend to hunt very small amounts, and this can translate into flutter very quickly at rocket speeds. not to mention since a rocket will never track perfectly straight, you have no idea which way is up, and therefore controls on the fins are basically useless..."

does this mean that if i use servos for such purpose , the idea would just fail ????????????
at least i can guess that we can have such powerful servos with hi torq that can sustane such load.???!!!!!
if causeitflies-RCU sees that it is just possible and doable , can you just giude me to the right combination of servos for example??


thanx guys and i would appreciate if ppl explained there point of view .
thanx guys and have a nice day
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Old 04-04-2004, 06:37 AM
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Default RE: reciever effecincy vs. Rocket speed ????

i think it's this: for high speed rockets, the servos won't work on fins. this is because of flutter, but also because of the speed you are traveling, almost instantly any control input would result in very fast movements. the gliders aren't really fast, and some even deploy the wings after a certain altitude or speed, so the control surfaces aren't doing anything until they deploy. Obviously, there are acceptions to everything. NASA rockets and even missles are guided via servos, albeit high powered and probably a little more sophisticated, but our toys aren't usually designed with this purpose in mind. The best bet would be to try it out in a remote area using the cheapest possible setup (without compromising safety or quality for the integrity of the test). That way when you put your expensive stuff in a rocket (if that's your intention) you will have a tried and true method. just make sure to check the laws in your area so as not to violate any.
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Old 04-04-2004, 12:56 PM
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Default RE: reciever effecincy vs. Rocket speed ????

As I said before, it depends on the speed and G forces. What type of rocketry are you into? High Powered or Estes type stuff? With the low powered stuff the extra weight of the RC gear will assure a slow enough acceleration that you could steer the rocket pretty much the whole flight, which wouldn't last very long.

Flutter is dealt with the same as any other high speed application.
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Old 04-05-2004, 02:26 AM
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Default RE: reciever effecincy vs. Rocket speed ????

wel thanx guys for your comments
well am mainly talking about mid-hi power rocketry....
but the question here dear causeitflies-RCU is, in such case do i need a servo with hi speed or hi torque ????
thanx guys )
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Old 04-05-2004, 10:32 AM
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Default RE: reciever effecincy vs. Rocket speed ????

High torque digitals should do the trick, with short control runs and minimal movement for the mechanical advantage. Oh, and very quick reflexes
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