Boomers!! Parkflyers for Beginners to Pros! Vid post 125 - Page 20 - RC Groups
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Jul 19, 2007, 01:57 PM
Registered User
Flyin C,
The funny thing about most brushless motors is there are no pos or neg wires!
You just hook them up anyways, and if its not turning the right direction, change 2 of the wires. Butch
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Jul 20, 2007, 12:18 AM
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olmod's Avatar
Originally Posted by aman_74
So which 20 gram motor?

I build my own from parts bought from Don,not sure on the weight of his super 20 kit but by all means ask for his advise by email ,he has a great tutorial on building ,cheers
Jul 20, 2007, 04:25 AM
Registered User
Ok, thanks, but you said that the motor wouldn't need to be built to obtain those numbers so I was looking to find out what pre-built version you were referrring to.
Jul 20, 2007, 05:16 AM
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olmod's Avatar
Oh i see a missinterpretation,what i meant was thats what can be acheived but by no means a max performance ,just a close comparison to what Butch was using,i have a lot of wind data records using GB stators and a few others
here is one that's popular.
New construction type motor.
12 off mcs 20 n50 mags from
15t of .5mm connected y

no load 15100 rpm@7.8 volts @ .6amp = 1935 KV

GWShd 7035 @7.4v @5amps =11200 rpm =273.27g = 9.65 oz thrust.

GWSHD 8040 @7.1v @ 8.6 amps = 8750 rpm = 372.90g = 13.16 oz thrust.


12 off mcs 20 n50 mags from
13t of .5mm connected y

no load 16800 rpm@7.2 volts @ 1amp = 2333 KV

GWShd 6030 @7.2v @ 13000 rpm @ 5 amps = 250.7g =8.85 oz thrust.

GWShd 7035 @7.2v @ 12000rpm @6.5 amps = 318.9 g= 11.62 oz thrust.
Jul 20, 2007, 04:58 PM
Sopwith Camel's Cousin
I was wondering if there is anything that I should watch out for if I were to try to build a Wildcat-Boomer with the following heavier motor and battery:

- 300-size geared brushless in-runner (~2.5oz.) swinging a 13" x6.5" slow flyer prop (17-19 oz. static thrust on paper)

- 8.4 or 9.6V NiCAD (~3-4oz.) battery

Perhaps I need stronger servos or not shorten the wing by 3.5 inches
or really lengthen the fuse to get the CG correct?

Jul 20, 2007, 09:19 PM
Registered User
Most of us are using 8" or 9" props and the booms are glued in to match.
With that big of a prop and using nicads, you would not need to cut down the wing.
I would use a 9 gram servo, like the GWS Naro for the ailerons and a 6g servo for the elevator.
The fuselage will just be a guess!
Just build it, keep the tail light and see where the C/G ends up. Let us know how it goes! Butch
Jul 21, 2007, 12:54 AM
Registered User
Flying llama,
You could always just use the inrunner direct drive and build a fast Boomer.
Heres one with a 180 Walkera, 3200kv. Using a 2 cell 1450mah lipo. It weighs 11.5ozs and is reasonably fast. Butch
Jul 21, 2007, 05:06 PM
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praymond's Avatar

Sorta Boomer

Butch, I was going to make your boomer, but got sidetracked into what you see here. It's still a boomer, but a tractor boomer. I didn't cut the wing, and am using a Esskay 400xt on the nose.

I'm going to make it along the lines of the F&L pictured below. It's a great flyer, smae motor.

Should I try for the balance point suggested in the WW directions since the wing is original size? Or because it's not a pure wing (has booms and a tail) do you think the CG will be different?

I was trying to put on the gear and see where it will balance before I mounted the tail group, just hanging blucor on the booms to simulate the tail weight.

Since you've used so many of these WW's i thought you'd have a much better feel for where to start a CG point.

Thanks. paul
Jul 21, 2007, 06:55 PM
Registered User
Most flying wings are about 15-22% back on the C/G.
So the WW's C/G will be forward of the conventional 30% back.
So try about 1/2" back more and maybe do a glide test in a nice plush grass field.
Jul 21, 2007, 08:57 PM
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praymond's Avatar
Thanks for the reply Butch. If you look at the left hand picture you'll see a line with 2 circles on it just behind the equipment bay. that's where the WW directions says to balance it as a wing. As a boomer, should I try for 1/2" rear of that mark to start?

Also what would be too much boom length, LE of elevator to TE of wing?? The spars are extra long, I was thinking of 6", and a tail group similar to the pic on the right.

Sorry for being a pesk, I appreciate your expertise!

Jul 21, 2007, 10:02 PM
Registered User
Hey Paul,
In general, the leading edge of the elevator should be behind the rear most trailing edge of the ailerons.
Yup, I'd start about 1/2" rear of the recomended C/G, but If I remember right, the guys that build the WW stock said the recomended C/G was off a bit.

To be safe, try putting in the wing size into a C/G calculator and select 30%.
Heres a online calculator.
Because the leading edge moves forward at the nose, draw a invisable line to see where the leading edges would meet if they were stright and measure from that point. Butch
Jul 21, 2007, 11:48 PM
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olmod's Avatar
Hi Butch and friends,
i bought some of these Lovely
and some 6g 4amp esc's some 3.3g servo's and i have a 24g 380 2sp pack and some 6m epp sheet.
Starting to look good for tlar mini boomer in the queue
Jul 22, 2007, 12:28 AM
Registered User
Hey Lez,
I'm right there with you. I ordered 3 of them, the ESC's and some small servos, a week ago.
I've got some EPP Flying Wings that are about 27"s, so they may be a good test plane to build a smaller Boomer from. They were designed for the IPS motor.
Or I may cut a WW down even farther, but the WW is not on sale at this time. Butch
Jul 22, 2007, 01:09 AM
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olmod's Avatar
On small stuff i like flat foam reinforced with bamboo shashlick sticks
i havent found a scource for that soft flexble hot melt glue that some are using available here in Oz yet, spose ill have to import that too
Jul 22, 2007, 02:18 AM
Sopwith Camel's Cousin
Originally Posted by Butch777
Flying llama,
You could always just use the inrunner direct drive and build a fast Boomer.
Thanks for the suggestion, but I am a near-sighted beginner flying in a small yard.
My interest in the Boomer is that it is a pusher (survive head-ons) that can fly slow (have a large prop and prop wash over the elevator).

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