Interesting speed plane

[Paul Taylor]

https://youtu.be/xfcjzXNQhv0?feature=shared

[Dennis Toth]

Very cool. sounds just like a 15 FAL glow on pipe. Did he use a two-step timer to jump to kick in for the speed run? I didn't notice any speed indication but seemed like it was right there with what glow FAI ships would do.

Best,    DennisT

[Paul Taylor]

Not sure just stumbled on it on YouTube.

[bill bischoff]

He uses RC throttle from the handle.  Reduced power gets it off the ground safely and allows it to get to a "reasonable" speed before full power is applied. Safer, more predictable, and better utilization of the available power. Speed about 300kph, similar to F2A models.

[John Rist]

WoW!  300 = 166 mph  That's fast in my book.  Electric speed should work.  Very short run times.      Problem is what class are you running in?   New rules are forth coming.  RC electric boats have had electric classes for years. 

[Mike Hazel]

Actually closer to 185 mph

[Lauri Malila]

..

[PerttiMe]

Below the video itself, it says:

Oct 21, 2021
This is a test-flight of a class F2G Control Line speed model powered by electric motor made by Nigel Frith UK class record holder on 17th October 2021 at Buckminster UK. Speed is approximately 300 kph (186 mph). Venue is the British Model Flying Associateion (formerly SMAE the Society of Model Aeronautical Engineers) purpose built tarmac circle. Engine speed control is by R/C built into the control-line handle. Motor revs to approximately 40,000 rpm and draws about 170 Amps.

[Brett Buck]

Motor revs to approximately 40,000 rpm and draws about 170 Amps.[/i]

   Not for long, though! It has to be counting on the fact that the thermal mass of the wiring is sufficient to keep them from melting just long enough to get the timing done.

    Brett

[Dennis Adamisin]

VERY interesting the power kick-up was awesome!  What struck me was tha the pilot seemed to be having a devil of a time flying it level.

Will this class be contested at the WC in Muncie in August?

[spare_parts]

   Not for long, though! It has to be counting on the fact that the thermal mass of the wiring is sufficient to keep them from melting just long enough to get the timing done.

    Brett

To some extent. Cooling air is used. Besides, solder would melt first. FAI RC class F5B runs >250A for brief periods. In Europe, there is something called "speed cup". Some of the largest electrics run 400A, >22kW. http://www.powerditto.de/scorpion/12N10P5050speed.html

[Dave Hull]

The trick is to not let the smoke out. Seen that at least once....  It's not quite as plug-n-play as the R/C foamies.

[Dwayne Donnelly]

To some extent. Cooling air is used. Besides, solder would melt first. FAI RC class F5B runs >250A for brief periods. In Europe, there is something called "speed cup". Some of the largest electrics run 400A, >22kW. http://www.powerditto.de/scorpion/12N10P5050speed.html

Am I reading this right? 52V, 22,665W, 400amps and only heats up to 190 degrees? I know it seems high but drawing 400 amps you'd think it would be a lot higher.

[Dave Hull]

The graph does not show the time base. The total "interval" was 2000, so we are likely seeing the sampling interval of the electronics. So if it was, for example, a 400Hz sample rate, it ran for 5 seconds. He notes that the bench test did not represent flight-like cooling. You could do the simple estimate of the thermal mass and the resistance kind of thing. Somehow I get the idea that these are for or were derived from F5B competition, which I think uses short duration zoom climbs. Low duty cycle but flat-out on climbs? The power represented in these small packages is really something....

[John Rist]

On the chart what are the interval units?  If the are seconds this was a long test.  2850 / 60 = 485 minutes.  This makes no since.  So my question what was the test time to reach the 190 deg??

The 5 second time stamp makes sense.

[Brett Buck]

Am I reading this right? 52V, 22,665W, 400amps and only heats up to 190 degrees? I know it seems high but drawing 400 amps you'd think it would be a lot higher.

   That what I was referring to above - 400 amps for how long*?  It's not 30 seconds.  The temperature is a function of the electrical power loss, the thermal mass (massxspecific heat), and time. You can shove 1000 amps through 28 gauge magnet wire - for a while.

    BTW, in the good old days, some of the stereo advertisements and claimed power ratings counted on this, they would pre-chill the amplifier, then run it into a dead short, and whatever the peak power was before it melted or caught fire was claimed as the power rating. The FTC adopted a rating method determined by the Institute for High Fidelity that fixed this sort of thing (and created new problems...). So this years "1200 watts peak power" Magnavox console stereo suddenly got derated to 3 watts/channel the next, with no other changes!    Car stereos are not subject to the same issue, and still have the loony claims.

     Brett

* with conventional insulation (PVC), depending on your opinion on margins, to handle 400 amps DC continuously, you probably need a copper conductor about 1 1/8" in diameter each way! That is also why you are never going to get an electric car charger that returns 400 miles of range in 5 minutes, no matter what battery technology you imagine, unless they hire bodybuilders to put the cord in for you!

     

[Dave Hull]

John,

The graph shows the test starting at 850 interval units and finishing at 2850. We are therefore assuming that the duration of the run was 2000 sampling intervals. Since the sample rate was not defined in the graph or the writeup that I could find, I posited that the sample rate might be around 400Hz which was entirely a guess. If so, then:

    (2850-850 sample cycles)/400 cycles per second = 5 seconds run time

If you wanted to make a different guess, that the recording system was sampling at 1Hz:

    (2850-850 sample cycles)/1 cycle per second = 2000 seconds run time, or 33-1/3 minutes

    I don't think any of us believe this is reasonable, so I suggested an assumption that made more sense about the sampling interval.

The article referenced the APD 400 Amp controller. Looking at that data sheet it did not specifically state the output format of the telemetry (sample rate) and was not clear to me if it was synch'ed to the adjustable PWM signal. If it is, then it is possible that the sampling rate can go as high as 500Hz which would mean that my guess is not ridiculous, merely unsupported by specific knowledge of the setup and the test. You can review the data sheet and see if you can gain further insight, here:

https://neumotors.com/wp-content/uploads/2022/07/20S_UHV-v1.4.pdf

Dave