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popec

Paraglider/ Parachute airspeed sensor

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Hi guys,
Does anyone have any experience with one of these?
http://www.flytec.com/Products/Air_Speed_Sensors.htm
paraglider airspeed sensor


or know of a similar product?

I'm about to start a thesis project, and think I might be needing to use one.

But I dont think I can afford the $1000+
data logger it plugs into. might have to try to make one.

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Hi guys,
Does anyone have any experience with one of these?
http://www.flytec.com/Products/Air_Speed_Sensors.htm
paraglider airspeed sensor


or know of a similar product?

I'm about to start a thesis project, and think I might be needing to use one.

But I dont think I can afford the $1000+
data logger it plugs into. might have to try to make one.



I think the Paragliding thingy looks pretty much the same as the one PD uses.
http://youtu.be/A8GC3newXQQ

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Hi guys,
Does anyone have any experience with one of these?
http://www.flytec.com/Products/Air_Speed_Sensors.htm
paraglider airspeed sensor
or know of a similar product?
I'm about to start a thesis project, and think I might be needing to use one.
But I dont think I can afford the $1000+
data logger it plugs into. might have to try to make one.


I think the Paragliding thingy looks pretty much the same as the one PD uses.
http://youtu.be/A8GC3newXQQ

Them Swiss products.. Might be too "slow" to test high speed landings...
***Vane trailing sensor speed
vane diam.: 16mm
wheel bearing: sapphire conical bearing
head housing: hard Nylon – vane mounting in chromium steel ring
starting characteristics: 0,5 m/s (1,8 km/h)
measuring range: 0,5 m/s – 33,4 m/s (1,8 – 120 km/h)
To Popec, depending on where you are, you might be able to ask Flytec (or some user of the products, generally paragliding manufacturers) if they can loan you one
scissors beat paper, paper beat rock, rock beat wingsuit - KarlM

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GPS tracklog maybe?
If you can set the record interval as short as possible, you might get some usable data on the cheap (? ( Just an idea))



That would give you Ground Speed (unless you can add the Air Speed sensor to the GPS Unit)

(.)Y(.)
Chivalry is not dead; it only sleeps for want of work to do. - Jerome K Jerome

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Yes I have exactly this on my Hang glider in conjuction with the logging gps vario.

What speeds do you want to study free fall or just canopy?
A stand alone wind meter like your S&TA uses would be better and cheaper and a very simple " Hall meter" can be bought even cheaper. Basically its a floating ball in a tube. All of this is for canopy speed studies not for freefall. Hope this helps

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The "trailing bomb" method of airspeed determination is a good one; it has even been used (either for pitot or just static pressure) for professional aircraft flight test. I think the PG magazines use sensors like the Flytec one for canopy flight tests.

I have used a handheld wind speed meter for canopy airspeed measurement. (Fine for full flight & below, but not swooping, besides the dynamic response may or may not be fast enough.) Some of the smaller gadgets have a greater inaccuracy range than I like. I also re-calibrated my early Skywatch model in a university wind tunnel.

When measuring airspeeds, I always tried to hold the instrument well out to the side of me, so that I'd have little flow blockage effect on the measured airspeed from my body. (Whether holding out front or to the side will also depend on where the display screen is on the gadget used.)

Impelller style gadgets do have a fairly good tolerance for not being aligned directly with the flow direction. One still tries to tilt the airspeed indicator directly along one's estimated descending flight path, and swivelling up or down a bit can help to see where the maximum value is recorded.

One has to be aware that an impeller type measurement will measure a True style airspeed rather than an Indicated type airspeed from a pitot tube, as far as I know. (ie, one wouldn't change the data to account for density altitude, as one would for rate of descent from a variometer, if trying to standardize the data to ISA conditions)

The trailing bomb might be less costly if you could find an older used model of variometer that still works with it -- find some HG or PG pilot who is upgrading to the latest & greatest. Maybe you want the vario anyway for rate of descent measurement, but maybe not, in this age of GPS's.

While GPS's can be used for airspeed measurement, even for aircraft with their greater speeds, taking out the effect of wind is tricky. One may do flights on two or three different headings and mathematically remove the wind component. But in skydiving we don't fly level, so three stabilized runs of 1 minute each in different directions is going to subject you to different winds at different altitudes.

While people will suggest using a GPS for speed measurement under canopy, I think the variation in wind and its great magnitude compared to canopy speeds (especially if one is doing high hop and pops to flight test a canopy) is going to make data reduction a nightmare and hard to get accurate.

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The 'Trailing Bomb" is a simple unit that works well enough in straight and level flight, but does not work well in maneuvered flight, as, like a skier being pulled behind a boat, if the boat makes a sharp turn, the skier actually slows down a bit and then gets wiped to catch up, the Trailed sensor will do the same.

I developed a Parachute Flight Data Recorder for the USDA Forest Service Smoke Jumpers, and a key requirement was an indicated air speed sensor. They jump special round canopies with a forward speed of about 10 to 12 MPH, it took two versions of pitot static tubes, that are mounted to the jumper, to make it work with a round and a square.

If you want to know what the air speed is during a hook turn, (or a maneuver), then the Trailing unit will not be of much use, if you are interested in the speed after the turn, (where the Trailing sensor is again inline with flight) then that should give you a reasonable representation of the performance.

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Thats a good point about maneuvering flight! I'll keep that in mind.

Ideally I would want to measure true airspeed.

I though a bit about using a gps data logger and flying in a circle to figure out wind speed and direction. But it would be a bit of a nuisance.

Wind speed and direction changing with height.
The accuracy of results might be bad. So i'm trying to avoid the gps data logger method at the moment.

The hand held wind anemometer idea sound a bit crude, but it would be interesting to see the data, the error from not having it perfectly aligned with the relative airflow may be negligible anyway.

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Thats a good point about maneuvering flight! I'll keep that in mind.

Ideally I would want to measure true airspeed.

I though a bit about using a gps data logger and flying in a circle to figure out wind speed and direction. But it would be a bit of a nuisance.

Wind speed and direction changing with height.
The accuracy of results might be bad. So i'm trying to avoid the gps data logger method at the moment.

The hand held wind anemometer idea sound a bit crude, but it would be interesting to see the data, the error from not having it perfectly aligned with the relative airflow may be negligible anyway.



True air speed is not measured, it is calculated from Indicated Air Speed, taking into account Air Temperature and Humidity to determine the actual density of the air that is pushing against the sensor.

Wind Speed has no affect on Air Speed, but it does change the Ground Speed. Taking GPS Ground Speed and Wind Speed to figure out what your Air Speed is, is not a good way to do it, as you pointed out.

The first generation PFDR Pitot Static tube was designed based on a traditional Pitot Static Tube design, and keeping it level and straight forward was very important. That requirement is very manageable on a ridged aircraft, but a challenge on a squishy jumper. Additionally, it worked well with a square, but not at all with a round.

The second generation Pitot Static Tube was designed using what I had learned from data recorded from the first one, the second generation Pitot Static Tube works as it should on both round and square canopies.

Gathering consistent and accurate data that represents the actual, and ever changing, environment that a canopy creates, and or sees, is not easy. Additionally, with out experience in reading raw canopy flight data, it will be tuff to determine if what you are seeing is a true representation of the flight, or not. The first thing that the FS said when we analyzed some of the points during a flight is, “the canopy won’t do that”, but after looking at the other instruments that would have been affected, it was clear that “it can and did”.

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