Posted by StarKannon on December 15, 2009 at 7:05pm
I will start off by saying this is not a traditional UAV, it is the launch vehicle for my invention a mass driver. Basically it needs to be a data collection point for flight telemetry, eventually expanding into work as an R/C and maybe eventually a fully UAV system. But for right now we are not heavily developing the projectile but focusing on the gun. So we need a system that can:1 handle an in-flight data link over a range of about ten miles.2. Be reconfigurable via a bluetooth wireless link while on the ground in the gun3. Switch control between a longer range zigbee/whatever radio system in flight.4. Send altitude, GPS, and attitude info back to the base station5. It must function to altitudes of 180,000 feet and at high g-forces6. The whole system must not be wider than 2" as it will not fit in the gun7. It must have a few I/O pins to trigger drouge and main chute deployment
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"12 meters long and has a bore of 2 " the projectile weights .5 kg and is launched at a speed of 5165 meters/sec"
v(t)=a*t
d(t)=int(v(t),t)=a*t^2/2
---
L_barrel=d(t_final)=v_final*t_final/2
t_final=2*L_barrel/v_final=2*12/5165=5ms
a=v_final/t_final=5165/5ms=1111551.04167m/s^2,
or roughly 113307 G.
all this assumes constant acceleration and infinite jerk at exit zone and at the beginning of the shot.
Real g values should be some 30% higher for smoother acceleration derivative.
ADXL330 (2grams?) would 'weight' around 226kg.
The correct solution for this technological challenge would clearly put any country as a leading military superpower.
"It must function to altitudes of 180,000 feet and at high g-forces"
The altitude limitation is not compatible with commercial GPS receivers which have altitude limit just to prevent from ppl like you making DIY ICBM.
G's above say 20G might require purpose-built single PCB fully enclosed no hanging cables.
Basically forget any open-source and most commercial projects for such requirements - you have to do it 100% by yourself or have a serious government grant plus several ppl and a lab working on it.
You have to add power supply requirement working to -50C and extremely demanding EMC compatibility requirement which asks for mil/aero grade chips. You might also need radiation shielding or triple redundancy because of the radiation up high (shielding from magnetic field and shielding from heavy particles is a different thing, you cannot afford 20l of water bucket around electronics I think).
This is not just challenging, this is insanely complicated task for somebody that asks for basic guidance on DIY forum.
Of course forget any modularity with those requirements: you are asking for all the most demanding conditions to be met simultaneously, maybe except vibration but that WILL come also say at 1-200KHz if you do something unstable at those speeds and G's.
Replies
v(t)=a*t
d(t)=int(v(t),t)=a*t^2/2
---
L_barrel=d(t_final)=v_final*t_final/2
t_final=2*L_barrel/v_final=2*12/5165=5ms
a=v_final/t_final=5165/5ms=1111551.04167m/s^2,
or roughly 113307 G.
all this assumes constant acceleration and infinite jerk at exit zone and at the beginning of the shot.
Real g values should be some 30% higher for smoother acceleration derivative.
ADXL330 (2grams?) would 'weight' around 226kg.
The correct solution for this technological challenge would clearly put any country as a leading military superpower.
The altitude limitation is not compatible with commercial GPS receivers which have altitude limit just to prevent from ppl like you making DIY ICBM.
G's above say 20G might require purpose-built single PCB fully enclosed no hanging cables.
Basically forget any open-source and most commercial projects for such requirements - you have to do it 100% by yourself or have a serious government grant plus several ppl and a lab working on it.
You have to add power supply requirement working to -50C and extremely demanding EMC compatibility requirement which asks for mil/aero grade chips. You might also need radiation shielding or triple redundancy because of the radiation up high (shielding from magnetic field and shielding from heavy particles is a different thing, you cannot afford 20l of water bucket around electronics I think).
This is not just challenging, this is insanely complicated task for somebody that asks for basic guidance on DIY forum.
Of course forget any modularity with those requirements: you are asking for all the most demanding conditions to be met simultaneously, maybe except vibration but that WILL come also say at 1-200KHz if you do something unstable at those speeds and G's.