How to measure true L/D on a balloon jump

[yuri_base 1]

Yo!

Winds aloft significantly affect glide ratio. Even a 20mph wind can throw off the glide ratio by as much as 0.4-0.5, depending on direction of your flight. This makes GPS data pretty much useless.

Wouldn't it be great if we could accurately measure winds aloft and adjust flight data accordingly to obtain the true L/D? Maybe launch a weather balloon? Well, how about riding in a perfectly good weather balloon and then jumping from it?

Balloon is simply a giant wind indicator. Start your GPS tracking when you lift off to accurately measure the wind speed/direction at all altitudes of your flight.

I came to this idea just recently when looking at a GPS track of one of the balloon jumps at Eloy where I accidentally turned GPS on long before the jump. Attached is data from this jump with wind correction.

Yuri

Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

[phoenixlpr 0]

Then you would realize that the atmosphere is not homogeneous.

IMHO you should have a wind-speed logger too :).

[SkymonkeyONE 3]

That's amazingly techno-geeky in a Kevin Orkin/Scott Campos kind of way, but it was cool to look at.

Chuck

[The111 0]

I'm not sure I understand why your L/D would constantly increase for the first 30 seconds of flight, unless you were consciously maxing it out more and more.

www.WingsuitPhotos.com

[nathaniel 0]

http://www.nkhome.com/ww/wwindex.html

I have one of these...but I'm leery of taking it on a wingsuit jump. The manual says the propeller degrades rapidly above ~60 mph. Tho you can get replacement propellers...

My advice is to do what your parents did; get a job, sir. The bums will always lose. Do you hear me, Lebowski?

[yuri_base 1]

Quote

I'm not sure I understand why your L/D would constantly increase for the first 30 seconds of flight, unless you were consciously maxing it out more and more.

Because it takes time to accelerate 230lbs meatmissile to 120mph horizontally. The jump was from 5.2K to 2.5K, in Phantom.

But you make a good point: when you're moving with acceleration, L/D (ratio of lift to drag) is NOT equal to relative-to-horizon glide ratio (ratio of horizontal displacement to vertical), since the vector sum of L and D in this case is not equal to and not directly opposite to the force of gravity.

Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

[KrisFlyZ 0]

I am looking forward to a season of GPS flights and believe that it works. I don't care that much about true L/D. I will always measure it against the wind direction when possible and that should give me a X.y+ number.

BTW, I jumped my Phantom today. OMG !!
Kris.