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Okanagan_Jumper

The WingNut...an Airspeed Indicator for wingsuit pilots

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Okanagan_Jumper


With my WingNut, it will be quite simple, I would simply tell him/her to aim for a certain IAS.



I have the feeling that either i'm misunderstanding you, or you are misunderstanding how it works.

The IAS for best glide will be unique to each person with their unique suit, for a given body position. Whatever it is for you, flying the one suit you own and that doesn't mean model, but actual suit, will be unique for you and won't be the same for anybody else.

If you and me have identical body proportions, but i'm heavier than you, my airspeed will have to be faster for the exact same body position and AoA.

If you and me are the same height and weight, but my arms are longer than you, my airspeed for best glide will be slower than yours. We might both be flying a c-race, but my c-race is not the same as your c-race, and they'll have similar but ultimately very different planforms.

If you and me are the same height, weight, and limb proportions, but i have bulky shoulders, a beer belly, or skinny legs, both the airspeed and AoA for best glide will be different. Your 'aircraft' and my 'aircraft' have both different shapes, drag, lift and weight distribution.

If you and me have different height, weight, proportions, etc. You might as well be throwing random numbers and have as much chance of being accurate as your target IAS.

Planes come out of factory all being the same shape and weight, but wingsuits come out of the factory not 2 of them the same, and the lumps of meat strapped inside are all also considerably different.

The only way you can find what the speed for best glide is for you, is to achieve the best glide possible, and then look at what the airspeed was when you achieved it. You can't do it the other way around, and that IAS for best glide for a specific AoA for a given very specific body position will only be true for you and nobody else.

And that's not even going into the fact that you can probably achieve your best glide airspeed at any glide between 0/1 to 3/1 or whatever is your best glide, since best glide sits close to your stall speed. So if your target IAS is 130mph, you can do 130mph balled up and flatspinning while going straight down, angle flying with the armwings fully folded and the knees dropped dirty, with dihedral and air-braking with your chest, etc.

You are however better of looking at the breakdown of speeds, since lets say flying with a horizontal of 120mph and a vertical of 40mph for a resulting glide of 3/1 gives you more info and feedback about what you are doing than just knowing you are doing 126.5mph.

On the ball horizontal but too fast vertical? You are probably arching, or going too steep while being draggy.
On the ball vertical but too slow horizontal? You are probably flying too flat.
Too slow vertical and slow horizontal? You are probably de-arching too much.
Too fast vertical and horizontal? You are probably going too steep.

Stuff like that
.

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More progress to report.

I have the prototype successfully capable of entering the target airspeed on the helmet unit alone, without the need for connection to a PC. Previously I had to enter the speed on a PC and then load the firmware into the device. Now I can simply enter the target IAS with the aid of a couple of buttons and an LCD, and that becomes my target speed.

The Flight Guidance/Flight Director function is mostly complete. I have the left and right vertical LED strips (15 individual LEDs each) on the visor indicating the pitch direction up or down to achieve the target IAS. The system will likely change several times before a final production version is in place, but one has to start somewhere.

The flight testing program will involve successive flights at varying IAS. I hope to plot a CL/CD curve fairly quickly with the results. A line drawn tangential to the curve from the origin should give me my (zero wind) best L/D speed. (Subject to the usual caveat that it's not a rigid wing...)

I secured the use of a grommet tool and for the C-RACE I installed two small grommets just inside of the gripper, and with the air of two nylon tie wraps, I secured the pitot tube assembly to the gripper.

Lateral guidance capability towards a magnetic track or a magnetic heading is on the radar. I just need to squeeze a little bit more out of my code to free up some memory. That or leave the Arduino behind sooner than planned and graduate to a Teensy board.

If flight testing phase goes as planned, I should soon have an electrical engineer and PCB designer working on getting something more robust for further testing.

That's all for now. Short video showing the target IAS entry procedure here: https://www.youtube.com/watch?v=HZuH4KAaRD8

Cheers,

John

Major WingNut Grand Poobah

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Hello fellow wingsuit pilots.

The Second WOWS Championship is this weekend at Skydive Perris. I have mostly completed the WingNut to a stage where I can use it in a race setting. I am not sure exactly what IAS I will use as a target during the distance rounds, but I am hoping to get a few practice jumps in tomorrow afternoon and Friday before the distance competition on Saturday.

I'm not a skilled wingsuiter and WingNut isn't going to magically transform me into one. However, I am hoping it will prompt my best performance in the distance round. I might as well sit out the speed comp B|B|.

Here is the latest poorly shot videohttps://youtu.be/NTHAwBbuy0U showing the airspeed guidance function in operation as I blow into the pitot tube.

And a blog about WingNut by a techy writer: https://blog.adafruit.com/2018/01/10/why-this-guy-needs-a-helmet-full-of-tech/

Go Canada!
Go John!
Go WingNut!

John Swallow
Major WingNut
"Design, Marketing, Testing...I do it all!"
WingNut Industries
Alliston, Ontario, Canada

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Hello.

I managed to do 3 flights with my WingNut system in January at Skydive Perris. I was satisfied with the performance and have continued with development. My first flight I set a target airspeed of 95 knots and that was much too slow for the distance round of WOWS. The second run was with 110 knots and that was much better performance.

The LED system in use then was accpetable but not ideal as it did not indicate absolute speed but rather indicated a speed above or below the target speed entered prior to exit.

The latest development has focused on designing an Android app for use with the Moverio BT-300 augmented reality (AR) glasses. I have a rudimentary app programmed now that indicates speed both in a digital readout and on an analog style airspeed indicator.

A 5 minute video [url=https://youtu.be/nlLZoD7mAOc]here[/url]. Skip to 3:45 mark for the app in operation.

Cheers

John

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Good work, John!

I have only one point to make: unfortunately, there's just no way to accurately measure airspeed without putting the Pitot tube on a vane a good distance from the body (0.5m is, from my experiments, an absolute bare minimum). It won't give undisturbed speed if mounted on a gripper only inches from the arm. Unfortunately, it's not possible with wingsuits to mount Pitot tube close to "fuselage" or wing and calibrate it to account for airflow slowdown and deflection, like they do on airplanes. Vane on a long stick is the only way for us.

Here's an example of a vane on a helmet:

[inline LD_Meter.jpg]

and on the belly:

https://vimeo.com/132279770

0.5m. Minimum. Sorry. Physics sometimes is such a bitch.

Godspeed!

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

LD_Meter.jpg

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Hi Yuri,

Why is there a .5m minimum in order to get into the undisturbed free stream air? I ask, because on my father's airplane, the pitot tube is under the wing and a mere 4 inches from the wing surface.

I took a break from this project over the summer while I spent time at the bridge in Twin Falls, but recently made some progress with the display. I have adapted a set of Epson Moverio BT-300 Augmented Reality glasses to function as a Heads Up Display (HUD). While not perfect at this point, I did 5 jumps with the set up on my G3 and it was very nice and not distracting having digital display of altitude, groundspeed, magnetic track displayed on the screen. Airspeed is still not functioning to a good standard, but I will still keep trying.

On the last two jumps, I programmed in a waypoint (using Google Maps coordinates) which was the place I wanted to deploy my canopy at, and the system successfully gave me navigation (direction/bearing and distance) information to this waypoint.

Currently, I can't raise the helmet visor with the glasses in place, so I need to work on that aspect. Either that or the AR industry needs to come up with something with a smaller footprint for skydiving applications.

As the system stands, I use information from a GPS unit and temperature/air pressure sensor sent to an Adafruit Feather BLE MCU, which then sends the formatted date via Bluetooth (BLE, or Bluetooth 4.0) to the Moverio. I don't use any of the Moverio's sensor information. Essentially, the Moverio is a display, with a Bluetooth receiver, and an android processor which uses a simple App I designed.

I spent the last two months preparing for a job interview in China which I was unsuccessful at, so now I can go back to devote some time to this project.

[inline G3_Moverio_Rotated.jpg]
[inline IMG_2877.jpeg]
[inline IMG_2815.jpeg]
[inline IMG_2816.jpeg]

IMG_2815.jpeg

IMG_2816.jpeg

G3_Moverio_Rotated.jpg

IMG_2877.jpeg

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Okanagan_Jumper

Why is there a .5m minimum in order to get into the undisturbed free stream air? I ask, because on my father's airplane, the pitot tube is under the wing and a mere 4 inches from the wing surface.



0.5m minimum figure comes from experience. When I created my first vane-based device in 2007-2008 which I called Z-Device ("Z" from Z-Hills), it had a short telescopic pole extending from the belly platform. I don't have it with me right now but I think it was about 8-10 inches total. What I found from Pitot measurements, my measured airspeed was only about 70% of my normal speed for max L/D (about 90mph in Phantom-1, I knew this flight mode very well). Also, the vane was visibly oriented too parallel to the body, like almost zero AoA. Which cannot be true, as my real AoA was somewhere around 15 degrees. It became clear to me that the vane is simply too close to the body and is already experiencing the slowdown and deflection of the air. Later, with L/D Magic running on iphone on a vane at about 0.5m from the belly, I found that the results are in general agreement with other methods of determining L/D. That's how I concluded that 0.5m is probably a reasonable minimum distance from the body.

Now, the planes' Pitots, as far as I can tell from NACA articles, are calibrated to account for their position near the wing or fuselage. It is also possible that the exact position of the nozzle by the wing was found in windtunnel experiments as having the same airspeed as at infinity. Since airplanes have fixed wing/fuselage configuration, there exist stable locations where the airspeed and pressure will be equal to that at infinity; these location can be used for Pitot and then no calibration adjustments are necessary.

There was this guy, Gibolin, active here in about that era, he made his own suit using very slick materials, and claimed L/D of 3.7 with it. He used a Pitot tube mounted on the helmet, at very short distance, like 2-3 inches maybe. That is why his measurements were wrong, he was sampling disturbed air, and that's why he's got this bogus 3.7 value. (In reality, his suit looked like a V-1, more or less, so L/D was probably about 2.5.)

Only vane. Only good distance from the body. No other choices. "Go vane or go home." Life's hard.

Even paraglider pilots put their wireless Pitot tubes on a vane on a string far away from the body:

[inline PitotPG.jpg]
Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

PitotPG.jpg

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I agree. That said, I got good results from my indicator when I placed it on the wing of my father's airplane. I tried placing it below the wing, but lost the Bluetooth signal.

I need to go back and do some more experiments with the style of pitot tube, but the static pressure sensor inside of the housing correctly indicated static pressure, so I think that the concept works fine. I just need to refine the size of the tube opening (and wall thinckness) to find the most forgiving (regarding angle of attack with respect to airflow) pitot tube head.

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Okanagan_Jumper

I got good results from my indicator when I placed it on the wing of my father's airplane.



It's possible that because of the wing's aerodynamic shape, the disturbed air does not extend that far from the surface, especially ahead of the leading edge where the head is placed in the picture. With our unaerodynamic bodies, we're not so lucky. But I'd be very happy to be proven wrong! I guess, a good experiment would be to put a thin long (1m?) pole on belly platform and tie several wool threads at intervals and see their 1) angles to the pole and 2) frequency of flapping, to see at what distance the threads start being parallel to each other and flap at the same speed.


For inline pics, use

[ inline nameofpic.jpg ]

with no spaces between opening bracket and "inline" and the ending one.
Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

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Here are some pics I found in my archives that show someone's homemade Pitot tube on a vane for a glider. As can be seen, since they don't know the special point(s) I talked about above (like where the Pitot is placed on your father's plane), they place it far away from the wing, from the leading edge, and on a vane to give more accurate measurements:

[inline PitotVane1.jpg]

[inline PitotVane2.jpg]

[inline PitotVane3.jpg]

[inline PitotVane4.jpg]

Unfortunately for us, a long unicorn on the helmet pointed forward won't be good in terms of safety. Same on the wing. So I think long enough stick with a vane on the belly is the best compromise.
Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

PitotVane1.jpg

PitotVane2.jpg

PitotVane3.jpg

PitotVane4.jpg

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