In air RPM and Speed Measurement
01-25-2002, 01:50 AM
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In air RPM and Speed Measurement
Speed and speed measurement is naturally a constant topic for pylon racers. Accurate measurement of how much motors unload in the air would also be very useful information.
A program has been found that purports to be able to determine the speed and rpm of a model aircraft in the air.
I thought I would post the link, just in case someone is adventurous and has the time to play with it.
SPEED MEASUREMENT and it came from the Pylon Racing Down Under web site.
A program has been found that purports to be able to determine the speed and rpm of a model aircraft in the air.
I thought I would post the link, just in case someone is adventurous and has the time to play with it.
SPEED MEASUREMENT and it came from the Pylon Racing Down Under web site.
05-09-2002, 01:50 PM
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In air RPM and Speed Measurement
I have an onboard tach made by PC/RC. On my scat cat with a TT40 pro, 9x6 apc and 15 % fuel I ws seeing 16,500 to 16,800 on the ground and 22,000 to 22,500 in the air. The tach will do real time or hold the highest rpm reached. I was careful not to put the plane in a dive, just took off did a few laps and landed.
You can calculate mph from rpm but you have to assume some percentage of prop efficiency. Based on 80% efficiency the numbers I got were pretty close.
You can calculate mph from rpm but you have to assume some percentage of prop efficiency. Based on 80% efficiency the numbers I got were pretty close.
05-10-2002, 10:32 AM
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In air RPM and Speed Measurement
Painless,
You picked up 6,000 rpm in the air with a TT pro 40? That sounds very optimistic. You must have noticed a huge difference in engine sound when it went up in flight. before I accepted that reading I would attempt to verify it. We cannot get that sort of increase on a racing Nelson or Jett.
Ed S
You picked up 6,000 rpm in the air with a TT pro 40? That sounds very optimistic. You must have noticed a huge difference in engine sound when it went up in flight. before I accepted that reading I would attempt to verify it. We cannot get that sort of increase on a racing Nelson or Jett.
Ed S
05-12-2002, 01:28 AM
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In air RPM and Speed Measurement
Here's a link to the tach:
http://www.iwc.com/pcrc/dt601.html
I always thought an engine gained about 3000 rpm in the air, and was surprised at the readngs I got. I did have two witnesses there. The reading I got on the ground agreed with my hand held tach though. I'm going to install it in another plane next week (not a racer) and will see what I get.
http://www.iwc.com/pcrc/dt601.html
I always thought an engine gained about 3000 rpm in the air, and was surprised at the readngs I got. I did have two witnesses there. The reading I got on the ground agreed with my hand held tach though. I'm going to install it in another plane next week (not a racer) and will see what I get.
05-12-2002, 03:35 AM
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In air RPM and Speed Measurement
That looks like a very interesting piece of gear.
One thought did cross my mind that might be relevant. Did you do a shutdown from full throttle before landing? If so, the engine might hit a very high rpm just as it is shutting down.
If you idled back and then shut down, the engine won't rev up as high since it will already have a low draw on fuel and air, and will be at a lower energy state.
One other thought was about the launch ... if your helper pushes the plane off pretty hard, this could raise the peak rpm also.
Next time you try it out, keep these things in mind ... and thanks for posting the info and link ... I'll be getting one.
One thought did cross my mind that might be relevant. Did you do a shutdown from full throttle before landing? If so, the engine might hit a very high rpm just as it is shutting down.
If you idled back and then shut down, the engine won't rev up as high since it will already have a low draw on fuel and air, and will be at a lower energy state.
One other thought was about the launch ... if your helper pushes the plane off pretty hard, this could raise the peak rpm also.
Next time you try it out, keep these things in mind ... and thanks for posting the info and link ... I'll be getting one.
05-12-2002, 12:57 PM
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In air RPM and Speed Measurement
My helper didn't push the plane that hard, certainly not like he would in competition.
I also shut the throttle down slowly and killed it just before touching down.
I was a little surprised at the readings myself, and as I mentioned above will be trying it again on a sixty size plane.
I also shut the throttle down slowly and killed it just before touching down.
I was a little surprised at the readings myself, and as I mentioned above will be trying it again on a sixty size plane.
05-13-2002, 08:16 PM
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In air RPM and Speed Measurement
Check this site out for onboard data loggers, it records temp and rpms.
http://www.aerosport.org/data_log.html
http://www.aerosport.org/data_log.html
05-22-2002, 11:53 PM
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Hey Painless,
Where are those up and coming tests///? I would be interested in what type of numbers you get the second time out...
I used to fly quickees with tt pro 40's. I always thought that they would unload about 3000 rpm's I got similar readings on the ground 16500-17200 with worked motor. Even our totally balls out tunder tiger that I got to turn 18200 with a apc 9x6 only turned 21300 with the unload prop, the simulated unloading of flight rpm's. That number sounds very optimistic and I'm curious to actually see what those tt's are uloading to in the air. Send some feedback, data, if you are continuing testing...
John W
Where are those up and coming tests///? I would be interested in what type of numbers you get the second time out...
I used to fly quickees with tt pro 40's. I always thought that they would unload about 3000 rpm's I got similar readings on the ground 16500-17200 with worked motor. Even our totally balls out tunder tiger that I got to turn 18200 with a apc 9x6 only turned 21300 with the unload prop, the simulated unloading of flight rpm's. That number sounds very optimistic and I'm curious to actually see what those tt's are uloading to in the air. Send some feedback, data, if you are continuing testing...
John W
05-28-2002, 12:10 PM
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In air RPM and Speed Measurement
We have not been able to fly lately. The site we use has been taken over by fire fighters as a staging area for helicopters to fight the Pecos wilderness fire.
I did manage to finish the plane and get a few test flights in. I'm going to install the tach this week. This plane is a Four star 60 with an ASP 61 on it. I'm not expecting to see the same reults as with the TT40 pro.
Some one who posted above was going to get the same tach, maybe they can give some input soon.
I did manage to finish the plane and get a few test flights in. I'm going to install the tach this week. This plane is a Four star 60 with an ASP 61 on it. I'm not expecting to see the same reults as with the TT40 pro.
Some one who posted above was going to get the same tach, maybe they can give some input soon.
