Using a Range Finder to Measure Model Altitude?
07-20-2017, 03:36 PM
#2
Boy would that be difficult! Unless you have a very slow plane and very steady hands. I use range finders all the time and I doubt I could get a reading from a moving object, heck a kite would be difficult enough. Remember you are essentially lasering a target and waiting on a return.
Good luck though, let us know if you're successful!
Good luck though, let us know if you're successful!
07-20-2017, 10:50 PM
#4
Join Date: Mar 2004
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We have the same limitation when flying within airport control zones, and I use the Spektrum Telemetry Altimeter.
Set to provide a warning at 400ft above ground level, the system gives a continuous tone or tx shake (or both as required) when the model is flying above 400ft (or your chosen warning height) and stops sounding when the model drops below that height again. To be certain, I set my warning for 380ft. To avoid annoying fellow flyers when the warning operates, I don't use the tone, and just have the tx vibrator sound. This has been working like a charm for me for several years. And that height limitation is a royal pain with any reasonably large model, never mind a jet
Gordon
Set to provide a warning at 400ft above ground level, the system gives a continuous tone or tx shake (or both as required) when the model is flying above 400ft (or your chosen warning height) and stops sounding when the model drops below that height again. To be certain, I set my warning for 380ft. To avoid annoying fellow flyers when the warning operates, I don't use the tone, and just have the tx vibrator sound. This has been working like a charm for me for several years. And that height limitation is a royal pain with any reasonably large model, never mind a jet
Gordon
07-21-2017, 03:08 AM
#6
O'Boy! Another 400' argument!! Been there, done that, and left that Club. We even had the local ATC controlled airports permission, but the management dictated the 400' That is because no one can accurately measure 400' by sight. Look at your runway and measure it, stand it on end to give you an idea. But, in truth, only way is telemetry. I'm not sure how accurate that is either, due to pressure altitude and density altitude, if the telemetry is read off of a pressure switch.
Best thing to do it is to "notify the local airport management, or ATC" as per AMA recommendations to fly above the 400'. Otherwise, this argument will do nothing but to destroy the friendly feeling at the Club, and create distention amongst the members.
Best thing to do it is to "notify the local airport management, or ATC" as per AMA recommendations to fly above the 400'. Otherwise, this argument will do nothing but to destroy the friendly feeling at the Club, and create distention amongst the members.
07-21-2017, 03:53 AM
#7
Its sounds complicated but its actually pretty easy to do. Only thing is the bits would cost a few hundred dollars.
If you haven't used microcontrollers then the arduino with the xbee backpack would be a great place to start. Someone with experience could build the device and program it in less than 6 hours. For a beginner who knows but it is good fun in any case. Once you know how to program the microcontroller you can make heaps of things pretty easily. LIghting controllers, servo drivers whatever.
Paul.
Last edited by paulhat; 07-21-2017 at 03:55 AM.
07-21-2017, 05:59 AM
#9
I am aware of some of the telemetry options. I have a Taranis altitude sensor in my 1/4 scale Cub.The first time I flew with it I left the audio reporting turned off until I was at 400ft by my judgement, then turned it on and it reported 590ft. It made me aware of how hard it is to judge altitude.
The DRCE field is directly under the approach to runway 17 and 2.4 miles from Centennial Airport Englewood, Co. Normally the airplanes approaching are at 1000 to 1500 ft above the field but on Monday one came by approx. 500 to 600 ft and a large model was flying at the same time. The Gulf Stream pilot reported a near miss to the tower and we had police on the field within 15 minutes.
Approx. 75% of the models at DRCE are small electric but they also exceed the 400ft restriction at times. It is unlikely that this type of model is going to utilize telemetry and I was looking for a way the club could monitor model altitude. I quit flying my jets at this field 6 years ago because of the restrictions.
The DRCE field is directly under the approach to runway 17 and 2.4 miles from Centennial Airport Englewood, Co. Normally the airplanes approaching are at 1000 to 1500 ft above the field but on Monday one came by approx. 500 to 600 ft and a large model was flying at the same time. The Gulf Stream pilot reported a near miss to the tower and we had police on the field within 15 minutes.
Approx. 75% of the models at DRCE are small electric but they also exceed the 400ft restriction at times. It is unlikely that this type of model is going to utilize telemetry and I was looking for a way the club could monitor model altitude. I quit flying my jets at this field 6 years ago because of the restrictions.
07-21-2017, 06:50 AM
#10
Hi Sid, I fly at a full scale airport (no tower, uncontrolled) and we use the spotter system to avoid full scale aircraft. But, I have found that by having a handheld aircraft radio I can hear any full scale calling out their approach long before I can hear or see them. This normally gives me plenty of time (like 5 minutes or more) to land and get clear before the full scale is anywhere near the field. They aren't expensive ($100-$200) and are extremely useful IMO.
07-21-2017, 07:34 AM
#11
Hi Sid, I fly at a full scale airport (no tower, uncontrolled) and we use the spotter system to avoid full scale aircraft. But, I have found that by having a handheld aircraft radio I can hear any full scale calling out their approach long before I can hear or see them. This normally gives me plenty of time (like 5 minutes or more) to land and get clear before the full scale is anywhere near the field. They aren't expensive ($100-$200) and are extremely useful IMO.
Good idea, I inherited a hand held radio a couple of weeks ago but has bad batteries which I intend to replace.
Sid
07-21-2017, 10:37 AM
#13
I have used my range finder on moving objects, BUT they were no where near as fast as even a park flyer. The issue with a range finder is it will tell you the distance from you to the object you are tracking, It will not give you the distance above the ground. BUT if you know the distance from you to the object and the angle you are sighting at it is simple math to determine the altitude. a X Sine C = c, or in our case, Distance from you to plane X sine of angle = altitude.
The range finder that I have is a Leopold, it will tell you both the distance and the angle at the moment you push the button. This feature is used by bow hunters to determine the ground distance to the target when hunting from a tree stand. Unfortunately its built in math will only calculate the ground distance to the object but not the altitude. Any smart phone should have no problem doing the math.
Another way if you are using a range finder that will do the math for ground distance then, Distance from you to plane² - Ground distance to plane² = Altitude², then take the square root of Altitude². Again any smart phone can do this math.
As far as waiting for the laser beam to get to the plane and back, the laser beam is traveling at around 186,000 miles per second, it takes about 4 seconds to go to the moon and back, or it can go around the world about 7.5 times per second. It is really fast, 400 feet is nearly instant. It will take that laser 0.003 seconds to get to the plane and back to the range finder. in that time if the plane is traveling at 200 mph the plane will travel just under .7/16 of an inch (0.432 inch).
The range finder that I have is a Leopold, it will tell you both the distance and the angle at the moment you push the button. This feature is used by bow hunters to determine the ground distance to the target when hunting from a tree stand. Unfortunately its built in math will only calculate the ground distance to the object but not the altitude. Any smart phone should have no problem doing the math.
Another way if you are using a range finder that will do the math for ground distance then, Distance from you to plane² - Ground distance to plane² = Altitude², then take the square root of Altitude². Again any smart phone can do this math.
As far as waiting for the laser beam to get to the plane and back, the laser beam is traveling at around 186,000 miles per second, it takes about 4 seconds to go to the moon and back, or it can go around the world about 7.5 times per second. It is really fast, 400 feet is nearly instant. It will take that laser 0.003 seconds to get to the plane and back to the range finder. in that time if the plane is traveling at 200 mph the plane will travel just under .7/16 of an inch (0.432 inch).
07-21-2017, 10:46 AM
#14
If you can laser a moving target like a model airplane I'd like to shake your hand, HA! My handheld rangefinder seems to take several seconds to get a return. Ive never used one that got an instant return, probably because the target didn't reflect the laser well, distortion , refraction etc..
07-21-2017, 10:59 AM
#15
I think the gang is giving good advice here .. get a member with telemetry-capable radio and a GPS or atmospheric (barometric) altitude sensor to fly at 400' and you will quickly get an "eye" for what it looks like. I bet you will be surprised at how low it is .. I was! We can certainly stay under 400' if we need to, but you'd have to be paying attention.
Dave
Dave
07-21-2017, 11:37 AM
#16
My Feedback: (3)
Another idea that my friends and I have tried just out of curiosity is to get someone with a quadcopter set up with fpv and just hover at 400ft back from the pits. Then watch the monitor while you're buddies fly there planes just to give you a rough idea. It's not an exact science but it gives an idea.
07-21-2017, 11:47 AM
#17
As far as waiting for the laser beam to get to the plane and back, the laser beam is traveling at around 186,000 miles per second, it takes about 4 seconds to go to the moon and back, or it can go around the world about 7.5 times per second. It is really fast, 400 feet is nearly instant. It will take that laser 0.003 seconds to get to the plane and back to the range finder.
01-14-2020, 11:44 AM
#19
Heres details of a cheap arduino altitude recorder ive built!
Looking for a simple altitude recording device, i found this simple arduino project Standalone-Arduino-Altimeter. Only three components & around 10 quid to build.
I decided to build one but the software need tweaking to suit. I wanted an altitude above launch. As it stood, it indicated pressure temperature and altitude with altitude min and altitude max. The altitude was dependent on both baro pressure and locality height. It could be possible to calibrate it but this would vary with weather. Also 2 decimal places was too much.
My software simply sets a zero altitude on power up/reset and a maximum in relation to this datum . Ive also set it to feet rather than meters! The bmp280 chip is apparently good for around +/- 3ft
My device mounted in a small plastic box 50mm X 35mm and weighs less than 20g. The plastic screw is mounted above the arduino reset button to act as a button to reset the altimeter to zero before flight.
If anyones interested i could post my revised software!
Looking for a simple altitude recording device, i found this simple arduino project Standalone-Arduino-Altimeter. Only three components & around 10 quid to build.
I decided to build one but the software need tweaking to suit. I wanted an altitude above launch. As it stood, it indicated pressure temperature and altitude with altitude min and altitude max. The altitude was dependent on both baro pressure and locality height. It could be possible to calibrate it but this would vary with weather. Also 2 decimal places was too much.
My software simply sets a zero altitude on power up/reset and a maximum in relation to this datum . Ive also set it to feet rather than meters! The bmp280 chip is apparently good for around +/- 3ft
My device mounted in a small plastic box 50mm X 35mm and weighs less than 20g. The plastic screw is mounted above the arduino reset button to act as a button to reset the altimeter to zero before flight.
If anyones interested i could post my revised software!
Last edited by dave.windymiller; 01-14-2020 at 11:52 AM.
01-14-2020, 01:17 PM
#22
