Brushless set up for a Great Planes Slinger

[G]

From memory the included prop should be okay but don't rely on me!

I couldn't use the APC prop shown in Bruce Richard's photos, I bought one and checked it with my wattmeter and it slightly overloaded my motor.  (The skinnier Graupner speed cam props draw less amps than the broader-bladed APC props.)

If in doubt, just don't use full throttle the first time you fly it, launch on 1/2 or 3/4 throttle and then fly on 1/2 throttle.  Personally I launch on 3/4 throttle and mostly fly on 1/3 throttle. 

I met a guy with a brushless Slinger, he was still close to a being a beginner, and he flew on full throttle the entire flight!  Boy that thing was moving, it was just amazing to watch him repeatedly almost crash it but somehow manage to survive.  He had fast reactions, I'll give him that.  He got away with it that flight, but of course the odds are against him succeeding too many times.  He couldn't understand why I suggested he throttle back, his view was "why on earth would I want to go any slower than the maximum possible?!"

[Tim Mackey]

Just a point about lower throttle equalling safety for ESCs. Even at low throttle, the motor will still draw FULL throttle Amps through the ESC...only for much shorter periods of time. If this current is a good deal higher than the ESC is designed for, then it could still damage it. It is NEVER a good idea to use an ESC that is not at least 10% greater capacity than the motor /prop combo can pull at WOT.

[Alex(biggles) Wilkins]

The prop supplied is a 5x4.3, the recommended prop is a 6x4 producing 220w or a 6x5.5 at 240w, does this mean the 5x4.3 prop is too small or big, ive tested the setup runs ok the esc hardly gets warm, its a 40a but the motor does get rather hot.  ive got an amp/volt meter and amps are with range ill get myself a watt meter.

[Tim Mackey]

The 5x4.3 should be fine, and the 6" may even require you to cut a little off the ends of the elevons anyway. The smaller prop will give higher top speed, with slightly less "pull" for climbs and acceleration.

The larger prop will simply mean less duration, a warmer and more stressed motor, and at 200Watts it is still well over 100Watts per pound - way over the minimum needed to actually fly it. The one thing I would say in favour of the larger prop is noise. The smaller prop will rev faster, and as you will see / hear, the noise is actually very loud - my slinger is my noisest model, bar none - even the IC models I own are "quieter"....certainly less offensive as it were. The combination of very high revs, and blades just a few mm away from the trailing edge is a noisy combination !

[Tom Goodacre]

Hi Guys,

             I have been flying my Slinger on a Kontronic 150 brushless with a 3S  2100 lipo and it goes like stink. Good servos are a must and I am using Hitec  metal gear BB's. I rate this model as more fun per pound(sterling) than almost anything else I have built.

[michael birks]

Hi all,

     just wondering if anyone can help,just got a slinger have been into i.c models for a number of years but am a little confused(OLD),when it comes to motors, lipo's etc,my slinger has the stock 400motor, my question is i have several 11.1v 1000mah lipos that i inherited could i use these??? obviously i would'nt run at full throttle i think the motor is rated at 7.2v but has some margin for higher voltage did some experiments on a setup and managed to burn the capacitor between the terminals,i also got 7.4v 1000mah lipo's to really not sure which brushless motor to buy to compliment the 11.1v 1000mah lipo's keep looking at BRC hobbies but it's a minefield please please can anybody help,many thanks

[Former Member]

[This posting has been removed]

[Tim Mackey]

I have a slinger - and it is on its 3rd motor - original brushed 400 was pants and ended in the bin after maiden flight

I fitted a tornado 2815 inrunner and used a 6.6 x 3 prop. One snag with the design is the full length elevons which restrict you to a small prop - as it was - I cut an inch off the ends to fit the 6" prop! It flys well enough, but is very noisy ( easily the noisest model I have ) as the small prop needs to  spin very fast in order to get any grunt - around 7500 RPM. I use a 3s 2200 Lipo and this ( on that prop ) gave around 180 Watts which was quite fast.

After flying it a lot for a couple of years I eventually burnt out the crappy Tornado motor ( in my experience, all the early Tornado branded stuff has been rubbish ) and earlier this year got a purple power motor from George Worley, a  2837-2200  which on the same setup produces 19000 RPM at a slightly higher 19A producing some 200 WATTS. The model now weighs 1lb  9oz after mrs Timbo re-kitted it at full power staraight at the deck and this works out at 117 WPB so still pretty reasonable.

Stock brushed speed 400s will run on 3s Lipo but as Eric says, will lead a hard and short life.Its not the actual voltage that kills em its the increased Amps as result of the high voltage. I would bin it, and buy something like the PP one I have, or maybe something like this from BRC etc. You need a pretty high Kv to spin the small prop fast, and maximum power handling should be in the 250 Watts category or so. On a 3s Lipo and say 180 Watts your amps will be about 17A - so at least 20 A ESC.

[michael birks]

many thanks guys,yes i have both 30amp brushed esc's and a couple of 30amp brushless esc's,the poor old speed 400 that i burnt the capacitor off lol gets to a high temp in quick time,yep rf all over the place now,i get it now i need some pretty high kv i think its rpm's per volt etc done a lot of reading on the forums for the whole day,a new learning curve but anything beats the oily old two stroke motors at least electric i can go fly out back on the farmers field without upsetting any of the locals with noise pollution etc,mind you i still get people concerned about how many fly's and bugs my prop kills per flight,it's never ending,thanks guys again kind regards mike.Eye suffolk/Harrogate

[Former Member]

[This posting has been removed]

[GrumpyGnome]

Mine had a Mega 16/15/4 in it.  Very fast, very very very noisy but great fun.

Watch out for flutter on both elevons and the tip 'fins'.

 GG