Fun fly

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10 Oct 2025 16:07 #1 by THE BLACKBIRD
Fun fly was created by THE BLACKBIRD
Thinking of drawing and building a fun fly plane to maybe build on my holiday or even i might do one before i go to see if its any good
I have a motor and ESC from when i was building the B36 years ago, seems now like a different life time 
The motor is a 4Max PO-3541-1070and the ESC is a 4Max 4M-40Amp that was going to turn a 3 blade 10x5 prop bearing in mind that there would be 6 of them on the B36
 
 
Now i seem to have forgotten most of the little i knew about the dark art of electrics, what would be the output from this motor and what prop would be needed
Ill get started on the drawing, about a 48 1200mm wingspan to suit the balsa sizes i think would be best, my drawings are always done by if it looks right it could fly ok 
 
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Thanks: Eric, Klipkopwildlife

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10 Oct 2025 17:48 #2 by Klipkopwildlife
Replied by Klipkopwildlife on topic Fun fly
On a 3S I think a 12x6 would work very nicely, you'll just short of 13,000 rpm.

Do it now, you may never get another chance
Thanks: THE BLACKBIRD

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10 Oct 2025 18:00 #3 by Quorneng
Replied by Quorneng on topic Fun fly
The 4 max site recommends a 12x6 for that motor but with a 45A ESC.
Probably because at 33A max continuous a bit more ESC "head room" is recommended.
   
Thanks: Eric, Klipkopwildlife, THE BLACKBIRD

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10 Oct 2025 18:55 - 10 Oct 2025 18:57 #4 by Eric
Replied by Eric on topic Fun fly
It's always best to have more amps available than the motor can want, then if you get the prop stuck on the ground and forget to shut the throttle, the ESC won't fry itself instantly.
That's where the WATTMETER comes in - with that between the battery and the ESC you can see what the motor is really drawing at full chat with the prop fitted.
Myself, I'd go for a 60 amp ESC, for more 'headroom'. (I don't recall seeing any 50's). Most people go for about 25% more than they think they will need!

if you are calm and collected when all about you are going berserk - you've missed something important!
Last edit: 10 Oct 2025 18:57 by Eric. Reason: typo
Thanks: Klipkopwildlife, THE BLACKBIRD

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10 Oct 2025 20:42 - 10 Oct 2025 20:43 #5 by THE BLACKBIRD
Replied by THE BLACKBIRD on topic Fun fly
The motor, prop and the ESC were 4Max recommendations ???? 
Last edit: 10 Oct 2025 20:43 by THE BLACKBIRD.

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11 Oct 2025 08:23 - 11 Oct 2025 10:49 #6 by Eric
Replied by Eric on topic Fun fly
Well, you know manufacturers (of anything) the smaller and cheaper they can get away with, the better for them!

Anyway, if you have an ESC that is more powerful than you need, it can be used again in something else, later.
That's why I mentioned the WATTMETER. You can SEE how much power the motor and prop are using. With an i/c engine, you can hear and feel when the mixture in the carby is correct. You cannot see electricity.

As a p.s. added later - If you have a 40 amp ESC, and it is showing close to 40 amps consumption at full chat, it's an indication that your motor/prop combi needs more amps than the ESC can deliver!

if you are calm and collected when all about you are going berserk - you've missed something important!
Last edit: 11 Oct 2025 10:49 by Eric. Reason: added a comment
Thanks: Klipkopwildlife, THE BLACKBIRD

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12 Oct 2025 10:14 - 12 Oct 2025 10:43 #7 by Klipkopwildlife
Replied by Klipkopwildlife on topic Fun fly
As mentioned in the Wots Wot thread, the supplied ESC is 40amp and I'm getting 24amps and 250watts on the Watt meter with a 12x6 prop. My feeling is that unless you are a competition flyer, very few of us fly at WOT all the time, I hear Eric's caveat  about a stuck prop but if you're not that aware you shouldn't be flying.

Do it now, you may never get another chance
Last edit: 12 Oct 2025 10:43 by Klipkopwildlife.
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12 Oct 2025 10:32 #8 by THE BLACKBIRD
Replied by THE BLACKBIRD on topic Fun fly
If 4Max recommended the wrong ESC then he should not or deserve to be in business, im going to use it anyway, we will see how it lasts 
Thanks: Klipkopwildlife

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12 Oct 2025 15:20 #9 by THE BLACKBIRD
Replied by THE BLACKBIRD on topic Fun fly
I was waiting for my boy to take me shopping at Tescos yesterday and popped into the shed to sort some paper out for the fun fly plan
He never showed up but i got a bit done had a sort through what little balsa i had and the scrap box
 
 
 
 
 
 
Need to order balsa for it and piano wire, now BalSsa cabin dont have the balsa i want but do have the piano wire
Slec have the balsa i want but dont have the piano wire 
SHEEESH 
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Thanks: Eric, Klipkopwildlife, jon.in.swansea

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12 Oct 2025 18:04 #10 by Klipkopwildlife
Replied by Klipkopwildlife on topic Fun fly
Hah, and you say you can't build any more!

Do it now, you may never get another chance
Thanks: Eric, THE BLACKBIRD

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12 Oct 2025 18:42 - 12 Oct 2025 18:48 #11 by Eric
Replied by Eric on topic Fun fly
Re the stuck prop  I was meaning when the model has tripped over, and trapped the prop - and the pilot not in command forgets to shut the throttle!

 

if you are calm and collected when all about you are going berserk - you've missed something important!
Last edit: 12 Oct 2025 18:48 by Eric. Reason: posted in wrong thread!
Thanks: Klipkopwildlife, THE BLACKBIRD

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13 Oct 2025 11:08 #12 by THE BLACKBIRD
Replied by THE BLACKBIRD on topic Fun fly
Thats not really building is it, 
Thanks: Klipkopwildlife

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13 Oct 2025 11:36 #13 by Flytilbroke
Replied by Flytilbroke on topic Fun fly
looks about right. Have a look at blackravenaerosports.com/
Martin was doing balsa deals among lots of other stuff.

Have a nice Day, unless I don't like you.
Thanks: Klipkopwildlife, THE BLACKBIRD

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13 Oct 2025 13:37 #14 by Klipkopwildlife
Replied by Klipkopwildlife on topic Fun fly
Gotcha Eric, done that myself.   Luckily no fire.

Do it now, you may never get another chance
Thanks: Eric

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13 Oct 2025 19:56 #15 by THE BLACKBIRD
Replied by THE BLACKBIRD on topic Fun fly
Looking for something to do while my parcel with the expensive balsa in turns up i found some 2mm balsa in the scrap box and cut it in pieces to go inside the leading edge between the ribs to carry the 2mm sheeting that fits over top and bottom of the leading edge
 
 
Then i doodled some lines on the paper for the tail feathers
 
Found some scrap 6mm and cut and dry fit to the doodles
 
 
At which point im out of scrap and things to do 
 
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Thanks: Eric, Klipkopwildlife, Quorneng, jon.in.swansea

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