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Okanagan_Jumper

The WingNut...an Airspeed Indicator for wingsuit pilots

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Hello.

Since entering my first wingsuit competition this past summer, the Wide Open Wingsuit Series (WOWS: www.wingsuitrace.org), I realized that, in addition to an obvious need for coaching, I also needed an airspeed indicator (ASI). I'm a sucker for instrumentation, but also I recognized that if I wanted to achieve the most performance out of my flying, I needed an ASI.

I've read the various articles coming out the last few years from people like Matt G., (and the other manufacturers/experienced wingsuiters and the info on TopGunBASE, and I fully understood their focus on angle of attack. When I started wingsuiting a few years ago, I too though that staying aloft for as long as possible was the name of the game. But that was wrong. Most especially for wingsuiters in the BASE arena, low angle of attack (high speed) is where the safety lies.

As a former glider pilot and light aircraft instructor, I know that over-reliance on instruments is a bad thing. We actually start flight training with concentration on the aircraft attitude: the relationship between the nose of the aircraft, and the horizon. Eventually, when mastery of that concept has been achieved, we introduce an instrument scan.

After the final 2017 qualifying round of the WOWS competition this past August, I left Kapowsin with a desire to design an airspeed indicator. I had read the posts YuriBASE had made over the years, and appreciated
thingshis efforts (the AofA vane, among others). Matt G brings up AofA often in his thoughts about wingsuit performance. It may or may not be known widely in the wingsuit community, but IAS is a good proxy for AofA. There is one unique indicated airspeed for every AoFA, for a given weight. For instance, in unaccelerated flight, an aircraft will stall at the same IAS (and AofA) for a given weight. Every time.

In the WOWS competitions, I had no chance at the speed round. I simply do not have the training to compete at a high level. In PPC comps, which I have not done, it is a given that I could not be competitive: I simply do not have the ability of sustained high speed/high angle flying necessary to increase kinetic energy prior to entering the competition window. In the WOWS distance competition however, I made the final round once and the semi final once. This I attribute to a lack of understanding on the speed necessary to fly for max distance. PPC comps rely to a large degree on flying steep then efficiently rounding out upon/prior to entering the window. WOWS has no such prologue: the signal is given, then everyone must go immediately to that IAS that will give the desired maximum performance. But how determine that performance? I suppose if we always flew in zero wind aloft conditions, we could, to a degree, use a GPS like FlySight.

Which all brings me to the WingNut. After 14 weeks of solid work, I finally took to the skies yesterday in a prototype airspeed indicator. It is a work in progress. I did two jumps yesterday, and the first one proved that a helmet mounted pitot tube was a bad choice. That was almost a given. The second jump however, brought encouraging results.

For that jump, I used a pitot tube mounted inside a turkey baster chassis, that I placed inside the space where the gripper goes on my left wing, this on my Freak 2. The Freak 2's gripper is very nearly aligned with the longitudinal axis of the jumper, allowing as accurate a meaure of stagnation (total) pressure as possible. The total and static pressures were routed via tubes to the differential air pressure sensor inside the body of the turkey baster, and then that electrical signal was routed via wires in the arm wing to the helmet mounted processing MCU.

The means of displaying airspeed is yet to be finalized. I have a few options. Stand by for further.

I believe what I have designed is very similar to what was suggested somewhere in this forum in the last year or two. It is not revolutionary, but at least for me, it provides, or will provide, what I need: a means to improve my performance in the coming WOWS competitions. I see no reason why the same device would not also be helpful for those competing in PPC style competitions.

So far I have the WingNut recording airspeed and other data at a rate of once per second, based on the time signal from the GPS unit. This allows marriage of the data from WingNut to that of FlySight, allowing a true portrait of aerodynamic performance.

Some have asked if WingNut is necessary, given all the data FlySight supplies. I think yes. My day time job (and sometimes night-time) is that of a commercial airline pilot. We make use extensively of GPS for enroute navigation and for stand alone RNP and GPS overlay approaches. But to keep the aircraft flying at its highest and most economical and efficient performance, we need IAS. We certainly have TAS at our grasp, but when Air Traffic Control asks us what our speed in descent (or the climb) is, we most always reply with "xxx knots indicated".

Anyhow, lots of words. I'm just happy that I have a valid proof of concept, and will work even harder now to work out the kinks. I'd like to throw down the challenge to anyone else who has an interest in such pursuits to see what they can come up with. It's not rocket science, although I'd appreciate the assistance of any rocket scientists out there.

The following data is the IAS readings taken at 1 second intervals during my 2 minute 20 second flight overhead Eloy yesterday. I wasn't consciously trying to maintain any speed or attitude. I was trying to incorporate the advice Matt G gave me prior to the first WOWS competition back in May in Georgia. There was stuff about legs and torso and, well, stuff.

In any case, the data seems to me, to accelerate and decelrate faily smoothely, with no completely wacky outliers.

Wish me luck in moving forward. Who knows, maybe the product reaches fine skydiving retail providers in the future.

Or not.

Cheers,

John Swallow

Head WingNut and Lead Program Designer
The WingNut Company

Alliston, Ontario, Canada
[Two 5 Zero] Two Zero 8 - Seven Four 6 Two
pilotjohnjohn@gmail.com

WingNut test flight #2. Dec 15/2017 Eloy, AZ. Freak2 wingsuit. WingTip mounted pitot tube.

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My photos were too big to upload. Here is a poorly shot 2 minute video showing main components. I am working on visor display so it is not shown. If I didn't mention earlier, I use separate GPS from FlySight to get a time stamp that matches FlySight so I can analyze data easily for things I am not recording.

https://youtu.be/0BHYYTsouj0

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Until I can get a Heads Up Display (HUD) working for a skydiving environment, I am searching for ideas on how to output speed. One such idea is to use an LED strip light system on the helmet where the pixel represents where the vertical path/target is in relation to the skydiver. If the pixel is above the center mark, that means the wingsuiter has to increase his pitch attitude (raise the "nose") to slow down. If the pixel is below the center mark, that means the wingsuiter must decrease pitch attitude (lower the "nose") to increase speed to achieve the target.

Two minute video to illustrate the idea here: https://youtu.be/ER0fJwR7g1M

With this method, the wingsuit pilot would have to input the speed target prior to exit. It would not supply absolute units, only pitch guidance towards achieving the target.

John

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Hi Leeroy.

WOWS competitions are great. At least the qualifying rounds are, I have not competed in the final round yet. It is an evolving format, but the enthusiastic promoter behind the idea, and the main sponsor are both committed to achieving an excellent product.

As I may have mentioned above, the PPC style competition favors those who can dive very steeply and round out to decrease their vertical profile depending on the category (speed/distance/time) upon or just before entering the competition window.

WOWS doesn't have the dive down component. Therefore, upon being given the signal to start the race (lead wingsuit rabbit kicking his feet up and down or something like that), all competitors have to go immediately to the speed for best distance or the speed that will get them across the finish line first.

Th start of the race is not based on GPS coordinate. The aim of the lead wingsuit rabbit is to be headed in the direction of the target, preferably a road or runway perpendicular (90 degrees) to the race lane. This makes it an easy finish line. The judges analyze the FlySight GPS later to determine an arbitrary starting point (it's not critical where that is) and then compute a point on the road/runway that is 90 degrees to that starting point. The 250 metre race lane is based on a line drawn between these two points.

To answer your question about the value of airspeed over groundspeed (which is what all GPS units output) I would say that an aircraft wing doesn't care how fast it is moving over the ground. That has as much relevance to lift production as does its speed in relation to the moon. The only thing that a wing cares about is its speed through the air. If the atmosphere was stationary, meaning no wind, we could use GPS to get absolute best performance. But that is not the case.

What we need is actually an angle of attack indicator. But that is a technical challenge. Most modern jets have a means of calculating angle of attack, but it actually IAS, or indicated airspeed, that pilots use (if not at higher altitue using Mach Number). It turns out that every angle of attack (AofA) has one and only one unique IAS associated with it for a given weight and aircraft configuration.

Additionally, there is one and only one AofA at which an aircraft (wingsuiter) will glide the farthest, in zero wind conditions. It doesn't change. Therefore, assuming a wingsuiter has a consistent good body configuration (as TopGun Base and Matt G are calling it) when in perfomance mode, there should be one and only one IAS to achieve this best performance, in zero wind.

So, how to get this IAS? That is why I have been working to make the WingNut.

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I like building things too and know the reward in getting it to work as designed is great, even if the usefulness is not way up there.

Your airspeed does not fully describe your horizontal performance. For example, I can fly really steep and fast and that doesn't mean my horz ground speed is good.

I fly while listening to GPS produced values and while they might describe your performance, they are less than ideal to tell you how you are flying. For example, if your tailwind changes through as you decend in your run, the numbers make you think you are doing better or doing worse as they change. Actually your flying might be largely constant but the numbers are not.

Adding airspeed to the GPS information would be helpful. How to combine that information into something useful while making the run is one of the underlying challenges.

Good luck with your project.

Note, if you have a PC, the Paint program in Windows has a Resize option that will allow you to make the files smaller. Look at the Crop feature as well.
Instructor quote, “What's weird is that you're older than my dad!”

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"...even if the usefulness is not way up there."

Why would you say that?

I have 19,200 hours in the air flying things from gliders up to my present gig as skipper of a B737NG. I find airspeed indicators to be of great usefulness.

How much experience do you have with airspeed indicators?

Here is what topgunBASE has to say:

http://topgunbase.ws/speed-and-aoa-faq/

"Low Angle of Attack = Safety and Options in BASE. Low AOA just happens to deliver different speeds for different suits and pilot combinations, so don’t get caught up in absolute speed numbers to compare arbitrary safety between pilots and suits. If wingsuits came with calibrated AOA sensors for each model of suit, we would all be locking onto tested AOA numbers for Best Glide and Best Endurance. We don’t have that just yet, so training by GPS and ‘feel’ are pretty much all we have for now."

Since IAS(CAS) is a proxy for AoA, I should think that an ASI for wingsuit pilots would be quite handy. If you agree with the author at TopgunBASE...

Cheers

John

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You can set up your flysight to output SAS, and then fly crosswind runs. A 30mph crosswind when you are doing 120mph will only add 3.5mph, and the SAS output takes into account differences in air density at different altitudes, so the beeper/voice will gain you good feedback on how you are doing. Set the beeper/voice to indicate total speed, and that's your airspeed right there.

To have an accurate idea of what the wind is doing give your flysight to the pilot and have him record the ride to altitude every couple of hours, and then use the flysight viewer's wind tool to check the wind's direction at different altitudes.

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Okanagan_Jumper

It may or may not be known widely in the wingsuit community, but IAS is a good proxy for AofA. There is one unique indicated airspeed for every AoFA, for a given weight. For instance, in unaccelerated flight, an aircraft will stall at the same IAS (and AofA) for a given weight. Every time.



Your above thinking assumes the same drag profile = body position. This is unfortunately not the case.

Multiple body positions can be used in flocking to achieve the same glide path but with varying IAS.

your reasoning above assumes the skydiver is like a fixed wing aircraft and can reliably maintain the same body position. In practise this may be a minor error but something to take note of in your testing.

For a speed competition it would be useful to get velocity in terms of a purely horizontal vector. This would probably require a combination of gps and IAS data. Then the results from flights in varying winds could be compared directly

Finally I think a higher sampling rate with some averaging to smooth out the data is probably a good idea.

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All good points from both posts. And an IAS indicator wouldn't be the best idea for flicking. The same for when I'm doing close in formation with my dad and my uncle, dad is lead setting the pace and the rest of us are NOT on instruments, we are glued to watching the lead aircraft.

The WingNut may not be the most suitable for all things wingsuiting, but it will definitely have its utility. Regarding changing body configuration, IAS will still be helpful if you consistently maintain the same configuration for that regime. For instance, one might have a body configuration for minimum sink (time competition in PPC) that is always the same. In this case, the IAS would be the same for that config, which is where the benefit will come from, the repeatability of the speed. Same for best lift/drag speed (distance in PPC).

I bought a grommet tool today and hope to install grommets inboard of the gripper baton through which I will loop tie wraps to secure the WingNut body. This should be less destructive to the suit than removing the baton and replacing it with the WingNut.

I hope to have the updated system ready for testing in early January. Ideally I would like to have the best L/D IAS determined by the time of WOWS late January.

Back to the lab!

John

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Okanagan_Jumper

Until I can get a Heads Up Display (HUD) working for a skydiving environment



Super cool project! For a heads up display, Google Glass works pretty well if you can broadcast the data over bluetooth. If you're interested in collaborating, it looks like you are well qualified to do the hardware side of things, I'd be happy to help out with the software side. I've basically already built the interface, but with only GPS data. Would LOVE to also have access to IAS.

[inline glass.jpg]
BASEline - Wingsuit Flight Computer

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I have the same idea, only I went with Epson Moverio. I haven't done anything with them yet but hope to one day. They require an Android app to be written and then the sensor data would be uploaded via a Bluetooth transceiver.

Once I get the system further along, perhaps we could see how Google Glass would work. The first version of the airspeed system used Bluetooth to transmit the data from wingtip to helmet.

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GoneCodFishing

You can set up your flysight to output SAS, and then fly crosswind runs. A 30mph crosswind when you are doing 120mph will only add 3.5mph, and the SAS output takes into account differences in air density at different altitudes, so the beeper/voice will gain you good feedback on how you are doing. Set the beeper/voice to indicate total speed, and that's your airspeed right there.

To have an accurate idea of what the wind is doing give your flysight to the pilot and have him record the ride to altitude every couple of hours, and then use the flysight viewer's wind tool to check the wind's direction at different altitudes.



Well, that sounds sort of good in theory, but what (airs)peed are you having outputted by FlySight? Ground Speed (GS), True Airspeed (TAS), Indicated Airspeed (IAS), Calibrated Airspeed (CAS), or Equivalent Airspeed (EAS)?

Not to be rude, but to a pilot, the above terms means something. And each (air)speed has its place in performance/operational consideration.

For my immediate purposes, I am only interested in IAS, because I want to be able to glide the furthest. WingNut will also have the ability to instantaneously determine spot wind velocity, much like modern aircraft do, because it reoords magnetic heading, IAS/TAS, in addition to the GPS track and groundspeed.

The attached photo is from a flight last night to Las Vegas. IAS is shown on the left (263/264 knots) and on right at top is shown Ground Speed 308 knots, TAS 463 knots, and wind speed 154 knots. At this altitude we fly with reference to mach speed, but once we are below about 25,000 feet it's all done with reference to IAS.

GPS's are great navigational tools, but a GPS is not what we would call a primary flight instrument. To tweak the absolute best performance (distance) from a wingsuit, some means of knowing IAS is the way to go. All assuming of course that one is an expert wingsuiter (I'm not one).

John

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Okanagan_Jumper

"...even if the usefulness is not way up there."

Why would you say that?

I have 19,200 hours in the air flying things from gliders up to my present gig as skipper of a B737NG. I find airspeed indicators to be of great usefulness.

How much experience do you have with airspeed indicators?

Here is what topgunBASE has to say:

http://topgunbase.ws/speed-and-aoa-faq/

"Low Angle of Attack = Safety and Options in BASE. Low AOA just happens to deliver different speeds for different suits and pilot combinations, so don’t get caught up in absolute speed numbers to compare arbitrary safety between pilots and suits. If wingsuits came with calibrated AOA sensors for each model of suit, we would all be locking onto tested AOA numbers for Best Glide and Best Endurance. We don’t have that just yet, so training by GPS and ‘feel’ are pretty much all we have for now."

Since IAS(CAS) is a proxy for AoA, I should think that an ASI for wingsuit pilots would be quite handy. If you agree with the author at TopgunBASE...

Cheers

John



My post was not meant to confront you or put a wet blanket on the idea. Design projects are fun regardless of actual utility, does not say the project has low utility, regardless of how it might sound.

If I want to increase my horizontal drive I get my tail way out there and have it a bit high, which gives more forward drive but this energy comes from increased vertical speed, to do more "work" against the wind. Increasing the forward and the vertical speed both add to the IAS, but you really don't know how the components break down unless you are linking that information to your vertical speed by GPS or some other tool (mentioned in a previous post). Say I am fixated on increasing my airspeed and just get steeper and steeper. I went 178 MPH in the vertical a few weeks ago, but I can't do that in the horizontal.

Sorry if I offended.

Experience with my face is about the only experience I have with airspeed indicators. When I first started flying, I was told it works pretty well, so that is the direction that I pursued.
Instructor quote, “What's weird is that you're older than my dad!”

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Meh, I was grumpy in my reply. No offense at all.

I thnk it is entirely possible, that linking IAS/TAS to GPS outputs will do just as you say. Currently, from what I understand, the competitors in PPC style competitions use altitude triggers generated by the FlySight to begin their"flare" into the competition box.

I'm curious as to what airspeed or other type of target they are aiming for when they begin that flare. If you have an airspeed indicator, it's simple. Once you know (through experimentation, or establishment of a true drag polar curve) your best L/D airspeed for the suit you are wearing, you begin your flare and transition smoothly to that speed. Every time. Obvioulsy the consistent top podium perfomers in the PPC competitions have their techniques for transitioning to max distance and time speeds, what is it they are aiming for?

The same will likely be true for the time competition in PPC comps. You enter the window and then smoothly transition to the the "minimum sink" speed (and configuration). Obviously, a change in body configuration will mean a change in the IAS/CAS relationship, as the pitot tube will be in a different orientation to the relative airflow. That said, different styles of pitot tubes are more forgiving than others in being slightly off of the relative airflow (thin walled open faced tubes are better than bullet shaped tubes).

Interestingly, for a fixed wing glider, aerodynamics theory states that the minimum sink speed is 76 percent of the (still air) best lift/drag (max glide) speed. Obviously, this relationship won't hold due to the changeable wing shape and configuration of a wingsuit pilot, but it may serve as a starting point to gather data.

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The first attempt I made at a best L/D instrument was in the July/August at CSC and Kapowsin. Here was my reasoning:

The best, sustainable, and zero wind L/D (glide ratio) in top wingsuits/wingsuit pilots seems to be around 3.0 to 3.5 to 1. I chose 3.25:1 for me. Probably unrealistic at the time, but that's what I chose.

This means for every 1 foot of altitude loss, the wingsuiter glides 3.25 feet.

If you consider the above as part of a right angled triangle, where the hypotenuse is the glide path, the horizontal is the adjacent side (3.25) glide distance, and the vertical descent distance is the opposite side (1 foot), then the glide angle (not ratio) we are looking for is:

tangent (glide angle) = opp/adj = 1/3.25 = 0.307

Using trig tables, the glide angle is 17.10 degrees

This mean that if my body was aligned parallel to my flight path, I would have abody angle tilted down from the horizon of 17 degrees, at a glide ratio of 3.25:1.

But I have a wing attached to my body. In an airplane or glider, the wing is attached at some angle to the longitudinal axis (specifically angle between wing chord line and longitudinal axis). This angle we call the angle of incidence. It is typically not zero. In a wingsuit we are constrained by anatomy. The wing looks to be more or less in line with body. The designers know the answer precisely. I assumed zero: the wing appears to be in line with my body, so an angle of incidence of zero.

So, the wing and my body are both tilted to 17 degrees down, if they are in line with my flight path of 3.25 glide ratio. But is that likely?

Well, for an average airfoil, the best L/D angle of attack is around 3 to 5 degrees, according to what I can generally find. What is the angle of attack? It is the angle between the wing chord line and the relative airflow. The relative airflow is defined as being equal and opposite to the flight path. Since we stated that the flight path is angled down at 17 degrees from the horizon, then the relative airflow is angled up from the horizon at this same 17 degrees.

I assumed (big assumption) that the best L/D Angle of Attack was 4 degrees. Since my flight path is angled down 17 degrees, and my wing is tilted up 4 degrees (the Angle of Attack), this means that my body angle is in fact 17 - 4 = 13 degrees down.

I tried using an app for the iPhone, a clinometer. This isn't the exact one, but it's similar: https://itunes.apple.com/us/app/tiltmeter-advanced-level-and-inclinometer-free/id391287447?mt=8.

It gives a voice readout of the angle of the phone to the horizon. I place it along my back and ran the ear buds from the phone up to my ears and listened to it out put my body angle as I flew. It was a challenge to get right so I scrapped that and went old school with a curved plastic tune and a ball bearing, see attached photo. I calibrated my body for 13 degrees down, and marker where the ball was in the tube and then used electrical tape to mark this target. I went cross eyed on those jumps.

Anyhow, me, an admittedly crappy wingsuiter made the final round at CSC WOWS and the semi final at Kapowsin WOWS. Why? Because science bitch!

The above techniques weren't perfect, but they got me into the ball park of best L/D performance.

I am hoping that WingNut (which has the capability to measure body tilt angle, BTW) will help me even more.

Sorry for the verbosity.

John

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Okanagan_Jumper



Well, that sounds sort of good in theory, but what (airs)peed are you having outputted by FlySight? Ground Speed (GS), True Airspeed (TAS), Indicated Airspeed (IAS), Calibrated Airspeed (CAS), or Equivalent Airspeed (EAS)?

Not to be rude, but to a pilot, the above terms means something. And each (air)speed has its place in performance/operational consideration.



Ground Speed (GS) - Nope, we are making wind (near) negligible and we are measuring the vertical component

True Airspeed (TAS) - Nope, as said above the SAS mode compensates for density and temperature changes

Calibrated Airspeed (CAS) - No really. The flysight has a smoothing logarithm, but i think that's not active for the beepers, and i don't know if this sort of calibration qualifies for CAS as opposed to just calibrating the pitot tube environent. If it is, then here's the winner

Equivalent Airspeed (EAS) - How fast do you fly that wingsuit? At the speeds and altitudes we fly wingsuits, EAS = CAS

Indicated Airspeed (IAS) - Either this, or CAs, depenidng on the flysight smoothing or not.

But you knew that already...

For the purposes of training with a wingsuit it works well enough, but if you want to make your own toys then that's awesome, good luck with it

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I like the scientific approach to maximizing performance.
This is why performance flying interests me, PPC competitions though.

Quote

The best, sustainable, and zero wind L/D (glide ratio) in top wingsuits/wingsuit pilots seems to be around 3.0 to 3.5 to 1. I chose 3.25:1 for me. Probably unrealistic at the time, but that's what I chose.



For what its worth i think a freak 2 is going to max at less than 3:1. Probably closer to 2.75. The top suits and pilots are probably just over 3:1 in continuous sustained.

Looking forward to see where this project goes.

ps. In PPC competitions the flare at the entry gate is a very dynamic event. I think that the efficiency and repeatability of the flare is where a lot of competitions are won or lost

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Yes DHemer, I agree. I was in my Jedei 3TT at the time. Still ptltobsbly a stretch for my ability, but I think the assumptions seem valid.

I just got my January schedule and I'm free the whole month so I'm going to to a training camp with Noah B and Chris G at Perris on the 6/7 of Jsnuary and spend the rest of the month training for the WOWS championship. I really hope I get some good solid data back for the C-RACE.

John

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