Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)
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would buy for $99
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Airspeed indicator for $99

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Old 08-19-2003, 02:34 AM
  #1  
AirSpeed-RCU
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Default Airspeed indicator for $99

The unit will allow you to determine top air speed upon landing by visual display (led). A yet to be determined amount memory will be used to store airspeed data for later analysis on a PC. Upgradeable to include audible airspeed warning with 2 set points and possibly RPM.
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Old 08-19-2003, 09:13 AM
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Default Re: Airspeed indicator for $99

You sell this unit ?


Originally posted by AirSpeed
The unit will allow you to determine top air speed upon landing by visual display (led). An yet to be determined amount memory can be used to store airspeed data for later analysis on a PC. Upgradeable to include audible airspeed warning with2 set points and possibly RPM.
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Old 08-19-2003, 01:10 PM
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Default Airspeed indicator for $99

Depends on the response I get. Including the " it should do this" replies. In other words suggestions are welcome.
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Old 08-19-2003, 10:13 PM
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Default Airspeed indicator for $99

Dansy

Sorry about evading your question it wasn't intentional.

I have research all the components needed for the basic functions and have done some prototyping. I will continue to develop the unit but I'm hoping for more feed back from this community for fine tuning and features to include.

Some have mentioned that engine temp would be nice. What do you think?
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Old 08-20-2003, 05:47 AM
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Default Airspeed indicator for $99

Hi,
My friend has one of those new ones. It uses a piece of fuel tubing to gather the information. It's kind of neat but gets boring pretty quick fooling with it. Also he can't retrieve the information until he gets home and downloads it and by then all the excitement is gone and your left with no one to brag to.
Now if three or four guys went in on it together the novelty wouldn't wear off so quick possibly.
Unless your constantly into speed planes that is.
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Old 08-20-2003, 02:23 PM
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Default Airspeed indicator for $99

Heres my thoughts on this. If the unit was inexpensive (under $100), I could see a need for this type of product.

My questions would be:

How big would the unit be?
Could it be plugged into your current receiver battery, or would it need a seperate battery?
How quick and easy would it be to swap out into another plane?
Would it max out? In other words at what speed, would it no longer work?

I think simplicity, ease of use, and a low cost will make a product like this a winner. There are already several products out there that seem to do everything including PC interface.

Keep it simple and cheap, and I think you have a market.
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Old 08-20-2003, 05:54 PM
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Default Airspeed indicator for $99

It would also be nice to be able to move it from plane to plane without much effort. ie. you fly, then your buddy flys, then someone else uses it...then you can compare the speeds for that same flying session.
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Old 08-20-2003, 11:16 PM
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Default Airspeed indicator for $99

I think it would be nice....but it would also depend on the size and weight....I fly pattern and 3D plane mainly, so weight is always on my mind...

Also I would not want additional battery, I use Duralites plus with 6 volt regulator..so a unit that work with 6 volt would be also very nice.

If the same unit could also include RPM I think it would give a better idea of what is happening with the set-up, mind you that one can always guess the in-flight RPM.

Originally posted by AirSpeed
Dansy

Sorry about evading your question it wasn't intentional.

I have research all the components needed for the basic functions and have done some prototyping. I will continue to develop the unit but I'm hoping for more feed back from this community for fine tuning and features to include.

Some have mentioned that engine temp would be nice. What do you think?
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Old 08-21-2003, 01:15 AM
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Default Airspeed indicator for $99

Originally posted by smchale
It would also be nice to be able to move it from plane to plane without much effort. ie. you fly, then your buddy flys, then someone else uses it...then you can compare the speeds for that same flying session.
This could be achieved quite easily, the only thing required would be a second pitot. The pitot (still under development) will likely be a short brass tube conected to the unit via tubing.

Dansy

I was thinking of adding extra sensors capabilities to the unit. RPM and Temp are the most likely.
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Old 08-21-2003, 02:32 AM
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Default Airspeed indicator for $99

Originally posted by AirSpeed
convicted to the unit with via tubing.

Dansy
Oh, that does it.
I hate convicts!~
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Old 08-21-2003, 02:46 AM
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Default Sounds real good-

My question is- How accurate will it be?

You always hear about radar guns being out of whack, and no-one ever really knows what the speed is-

If I am driving down the street in my car, how accurate would it be compared to my speedometer (for example-)?

I have a Patriot and Jett-50 and I think I am a little over a buck- some folks say 150MPH (?)

I ould happily pay $100- if it is fairly accurate and easy to operate- Don't need RPM's or engine Temp. tho-
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Old 08-28-2003, 02:26 AM
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Razor

Sorry about taking so long to reply, I've been away.

I'm not quite sure about the accuracy yet. I don't want to guess because the resolution of the pressure sensor is the most influential factor and I won't know which one I'm going to use.

What is the minimum accuracy you'd want?
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Old 08-28-2003, 02:36 AM
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Default 5-10?

Within 10MPH would be fine with me- I am just a sport flier that is curious about my different plane/prop. combos-

Put me on the list for one whenever it is ready to go-

Good luck and keep us all posted!
james
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Old 08-30-2003, 01:57 PM
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Default Airspeed indicator for $99

The speed logger would be a great function if it could log say 10-15 minutes of data. If you're looking to add channels, my preferences, in order, would be engine rpm, temperature, & altitude.
The sensor technology is out there to do this accurately, but the trick will be to find something that you can use that is already in mass production (read cheap). A possibility would be a manifold pressure sensor from a popular make of car.
Calibrating the pitot won't be hard, but the mounting on the respective airframe will impact accuracy more than anything.
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Old 08-31-2003, 12:52 AM
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Default Airspeed indicator for $99

I not sure yet how much ram will be available for data collection. That will be determined when I choose which micro I'm going to use. The length of time you'll be able to store will be adjustable (samples/sec).

I'm thinking RPM will most likely be the extra function.

As far as sensor technology goes, I think a part used on a car would probably have an inflated price, due to the nature of the car parts business (auto = >$). Another problem in terms of the pressure sensor is it needs to be high resolution. The pressure created by a pitot at 200mph is only ~0.75 PSI and the PSI at 20mph is only 0.0075.

Yes, mounting of the Pitot will be critical it terms of accuracy. For this reason I've been trying to come up with a good way to mount the pitot on the top of the tail fin. I think this would be the cleanest air around the aircraft.

What do you think?
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Old 08-31-2003, 06:17 AM
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Default Airspeed indicator for $99

For planes with a prop in the nose, top of the vertical fin, or on the wing would probably be the best places. Just get it out of the propwash.

For pusher-props, DF, and turbine, the nose would be your best alternative....

Now, for functions... Speed and RPM would be great, but one should have some way of checking at least max speed and the RPM at said speed, in the field. Perhaps a small 3 digit display showing RPM in 100 RPM increments?

And one other thing: Switchable between KPH and MPH in the display.

This could be a really nice gadget for most planes if the size, weight, and price is right...

A feature i would like in addition is a altimeter that could display at least max altitude. Perhaps a addon-unit?

One question about the pitot-sensor: Would it use a static-port as reference pressure, or would one just calibrate it on the ground? Without a static-port, the unit would indicate less airspeed as you gain altitude...
After all, the pressure drops roughly 0.0145 PSI for every 10 meters / 40 ft of increased altitude...
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Old 08-31-2003, 07:30 PM
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Default Airspeed indicator for $99

Good advice. Thats the first request for KPH, won't be too hard to implement. Altitude would have to be an add on feature due to the price of the sensor. I aim keep to the unit price at $99 as per the poll.

The unit will have a static port.
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Old 08-31-2003, 10:01 PM
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Default Airspeed indicator for $99

Someone in our club recently built a data logger to record altitude data.

He had some trouble with it... he placed the unit in a "Pilatus Porter" for a test run... apparently the air pressure in the fuselage varied considerably during the flight, and not only because of the changes in altitude. The faster the plane went, the lower the airpressure got in the fuse. This showed up when he ran the data through his laptop.

So maybe a sensor with a static port isn't such a brilliant idea after all if you want to get accurate data... especially on speed planes...
Unless you only use the static port to calibrate the unit to "zero airspeed" on the ground just before the start of the flight and then not use it for the rest of the flight... during flight only the "dynamic pressure port" should be used...

Is this at all possible? I should think so...
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Old 08-31-2003, 10:55 PM
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Default Airspeed indicator for $99

Rudeboy: Without a static port, the only accurate data will be the speed indicated at the same altitude as where the sensor was calibrated, on the ground that is (or slightly above it)...

The higher you climb, the lower the indicated airspeed.

Now, with an altimeter onboard, one could probably use it to adjust the figures as well, but as stated, it's expensive...


...and as to the lower pressure in the fuselage, you could easily put another hose to the unit, and put the static port on the side of the fuselage...
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Old 08-31-2003, 11:06 PM
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Default Airspeed indicator for $99

Originally posted by RampRat
Rudeboy: Without a static port, the only accurate data will be the speed indicated at the same altitude as where the sensor was calibrated, on the ground that is (or slightly above it)...

Well... one could also carry a handheld barometer and use that to calibrate the unit before flight... I have a wrist watch with this function... and it's pretty accurate...
But it would be too much of a hassle (and destroy the 99$ goal probably).

The reason I proposed to use the static port for calibration on the ground only is because I think a second line is too much of a hassle also... plus it would have to be placed very precise to get an accurate reading.

Edit: Oops sorry Ramp... I didn't read you post the right way...
Yeah, I know, it would show slower speeds because of the altitude...
But you would want to fly as possible anyway... because lower airpressure means less engine power...
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Old 09-01-2003, 02:11 AM
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Default Airspeed indicator for $99

A static port is a must. A change in altitude of 500 ft is the equivalent change in pressure seen at aprox 80 mph.

The problem with the "Pilatus Porter" setup was probably due to the effect of air flow around unsealed portions of the fuselage. These openings are even likely to be affected by prop wash. A test to determine if this is the case might be to collect data with the engine at different rpm while the aircraft is stationary.

If you have a chance to try this ( or convince the guy with the setup to do it) let me know the results. It would be valuable information.
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Old 09-01-2003, 04:39 AM
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Default Airspeed indicator for $99

Probably the best and most accurate method is to do a combined pitot/static tube, but that will add to the cost of your proposed design.
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Old 09-01-2003, 08:18 AM
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Default Airspeed indicator for $99

Originally posted by Rudeboy

Edit: Oops sorry Ramp... I didn't read you post the right way...
Yeah, I know, it would show slower speeds because of the altitude...
But you would want to fly as possible anyway... because lower airpressure means less engine power...
....and less drag...
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Old 09-02-2003, 03:49 AM
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Default Airspeed indicator for $99

Originally posted by Mluvara
Probably the best and most accurate method is to do a combined pitot/static tube, but that will add to the cost of your proposed design.
The design includes a static port. The output of the sensor is the difference between 2 ports (pitot & static). It is not possible to get accurate air speed at different altitudes and barometric pressures.

It may be possible, with certain aircraft, to have the static port in the interior of the fuse instead of having the static port outside the fuse (location issues can cause inaccuracy). I'm just wondering how much ariflow past, lets call it a drafty, fuse changes the pressure inside the fuse.
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Old 09-02-2003, 02:23 PM
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Default Airspeed indicator for $99

On features...............Three Words

SWITCHABLE CRUISE CONTROL

In other words, I can switch a preset cruise control on and off from the transmitter.
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