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100 MPH Mighty Mini Corsair!

#1
Hi, I just made the new Corsair and thought I would share my setup for some awesome speed! I used a funfighter motor with a 6x4 prop. It went fast on 3s, but according to some weird German Doppler effect software it went 100.4 MPH on 4s give or take. Not sure how accurate it was, but it seems like it was in that ball park. I used nanotec 3s 1300 and a 4s 1300 25-50c batteries. Here's the video with 3 and 4s passes. 3s average was 83mph and 4s average was 98mph.

 
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#4
I've used WOS before and it's pretty accurate IF you feed in the correct temp and IF you fly close to the pickup.
With Doppler measurements you need to think of your sound waves as ripples on a pond. If these ripples were made by a bucket with a drip in it and the bucket was standing still, you'd have a bunch of rings with a center where the drip hits the pond. But now move the bucket. The next drip from the bucket hits the water closer to one side of the last ring and farther from the other. The difference in this distance is dependent on the speed of the bucket. The pitch you here from a horn on a train changes as the train goes by you. This is the reason, the sound of the horn (which is just ripples of compressed air) is compressed on approach side (raising the pitch) and stretched on the retreating side (lower pitch). WOS shows you the high pitch, the low pitch and then figures out the speed (based on the difference of the pitch). Because we're measuring sound the speed of which varies mostly with the temperature of the air, you feed the air temps into WOS.

Think a little more. IF you record your plane going past with a recorder which is quite a bit away from the airplane, you are essentially measuring the flatter part of those rings where as if the recorder is directly under you get pretty much the whole effect. So try to fly right over the recorder which is easy because you can put that out on the field somewhere and get out of the flight path.
 
#6
I've used WOS before and it's pretty accurate IF you feed in the correct temp and IF you fly close to the pickup.
With Doppler measurements you need to think of your sound waves as ripples on a pond. If these ripples were made by a bucket with a drip in it and the bucket was standing still, you'd have a bunch of rings with a center where the drip hits the pond. But now move the bucket. The next drip from the bucket hits the water closer to one side of the last ring and farther from the other. The difference in this distance is dependent on the speed of the bucket. The pitch you here from a horn on a train changes as the train goes by you. This is the reason, the sound of the horn (which is just ripples of compressed air) is compressed on approach side (raising the pitch) and stretched on the retreating side (lower pitch). WOS shows you the high pitch, the low pitch and then figures out the speed (based on the difference of the pitch). Because we're measuring sound the speed of which varies mostly with the temperature of the air, you feed the air temps into WOS.

Think a little more. IF you record your plane going past with a recorder which is quite a bit away from the airplane, you are essentially measuring the flatter part of those rings where as if the recorder is directly under you get pretty much the whole effect. So try to fly right over the recorder which is easy because you can put that out on the field somewhere and get out of the flight path.

That's a great way to explain it. The recording I used was a pass from about 10 ft away, so I will try to get closer next time. Thanks!
 
#7
From what I've seen in Nic's flight videos this looks to be right around 100. Nice job flying the thing, it must be pretty twitchy.


With the size of the control surfaces, its actually not too twitchy at speed if you are on low rates. I think my low rates is about 15 degrees on everything, with 35 expo. Thanks!