EasyStar #6 : Doppler speed testing of my FPV EasyStar

Ken and I went had been trying to measure the speed of our planes using a HotWheels radar gun, but it just wouldn't pick up on the planes unless you just about hit the guy with the gun. So instead Ken found some software ( http://www.sprut.de/electronic/soft/scope.htm ) that works out the speed based on the doppler shift in a WAV file. Ken set up his digicam, got videos of both our flights and grabbed the sounds of the flybys using Goldwave. There was a fair wind that day, so I took the average of a few flights and got over 50mph so I was quite pleased.

In the air equipment:
Multiplex EasyStar
- aileron modification
- WASP 2835 220w brushless inrunner with APC 6x4 prop
- WASP 33A ESC
- BRC Hobbies 2200mAh 20 3s battery
- Futaba 319DPS rx
- GWS Park servos

FirstPersonView.co.uk FPV Kit
- KX131 with pan and tilt
- Immersion RC 2.4Ghz video tx
- powered from flight pack

On the ground

- Futaba 6EXHP tx

- Goscam GP-707 video rx, 3dBi antenna
- Pinnacle Video Transfer (set to "Better" quality")
- 4Gb generic memory stick
- all powered by 1700mAh 3s (via 5.25v UBEC for the PVT)
- VR1400 video goggles

Category:

Science & Technology

Tags:

• FPV
• First
• Person
• View
• KX131
• Multiplex
• EasyStar
• Doppler
• Shift
• Speed
• Test
• Weetslade

[cortexdnb1]

what do you think of the vr1400 goggles im thinkin of gettin a pair myself

[carlosthecactus]

@cortexdnb1 Hi, I haven't used any others so can't say where they rank on the market but I can say that I like using them. They are pretty comfortable and have enough brightness to give a good picture. The remote control never really seems to adjust brightness/contrast but the current settings are good enough. I have used the on my Wii and that works nicely too. You need to be careful with them, mine have some white marks on screen where they caught the sunlight once, keep away from direct sun.

[carlosthecactus]

@cortexdnb1 The goggles come with a separate rubber eyepiece, you really need this if you are using them outdoors otherwise you get reflections of whatever is behind you on the screen. Actually I tend to pull my hood up and over the goggles to cut out this side glare. I don't think this would be unique to these goggles. They use a standard nokia type phone battery so you can get spares if you want to use for long periods away from base, I've run for about an hour with no battery issues...

[carlosthecactus]

@cortexdnb1 I can put it quite simply, if my current pair broke, I would quite happily buy another pair of them .

Are you taking up FPV?

Thanks for watching! :D

[stevessub]

isnt weetslade on the flight path for newcastle airport.

[carlosthecactus]

@stevessub Not quite, It's about 1.3 Km off the straight line path and about 4.2 from the end of the strip. We can certainly see the planes as they come in/out but we are in no danger of interfering with them.

[Brillig2]

Here's the calculation.

R = high frequency / low frequency

S = speed of sound (768mph)

speed = (R-1) * S / (R+1)

For example, in one of the runs we have 1981 and 2315 Hz.

R = 2315/1981 = 1.1686

Speed = 0.1686 * 768 / 2.1686 = 59.7 mph

I derived this earlier today and used the data in your video to confirm I was doing it right. I did this because a Cessna 172 flew extremely low over the house this morning, and I want to estimate how close by the doppler effect, etc.

[petleh82]

I use a gps logger to get the speed of my planes. About $30 on ebay, and the cool thing about those is that you can put the logged data into google earth and see a track where you flew. And about your goggles, i think it's about time to do the ski mask mod, that will make them much much better ! :-)

[cortexdnb1]

@carlosthecactus yeh im going to try and get all thequipment soon for a parkzone radian glider. cant wait looks so much fun