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Nov 24, 2021, 06:19 PM
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I recall (and my memory is only so good...) that the ground peak RPM on the Nelsons were typically 27K or so. Unloaded in the air they might have been pushing 30K, Small props, though, and most were using carbon fiber propellers by then.

The conquest (Cox) would blow up rods if you tried to run them that fast. The Conquest had come along before I started racing QM, so I never ran the Rossi, Taipan, K&B, etc.

I still miss those small planes, and the wide variety of designs you could see at a race. It seems as if these days it's mostly P-51 derivatives of some sort, or the "Miss Ashley" type which are a p51 like fuse with a lear jet wing/tail shape. Not a tremendous amount of variety. It's much easier to get a decent engine run in a low wing plane, with the tank up higher. We're not running crankcase pressure on the tanks any more, only muffler pressure, and tank position is more important with the .40 size QM planes these days.
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Nov 25, 2021, 08:02 PM
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I like the noise so I know its running and if you fly close and low the oily smoke will keep the vampire bugs at bay .i dont smoke do my plane has to.
Heres specs on that motor .
The q .15s are about 2.5 lbs about 40 oz .
Considerably more if i paint them .
My rossi mark3 uses a 6x10 prop but its for flat out flying .
I cant see why a 6x5.5 wouldnt work as long as you give it time to get moving .
I my electric tony used a 8x8 and has power to spare .
Len
Nov 25, 2021, 08:10 PM
Registered User
Youre welcome to use my field any time
The noise doesnt bother the bison at all

It sucks that a lot of fields are noise sensitive and are being turned into acreages like The one in Prince Albert near me .
Talk about a waste of farmland .
Large groomed lawns with a house in the middle .
Nov 26, 2021, 11:59 AM
Modeling Masochist
Terry Till's Avatar
Quote:
Originally Posted by leo turt
I like the noise so I know its running and if you fly close and low the oily smoke will keep the vampire bugs at bay .i dont smoke do my plane has to.
Heres specs on that motor .
The q .15s are about 2.5 lbs about 40 oz .
Considerably more if i paint them .
My rossi mark3 uses a 6x10 prop but its for flat out flying .
I cant see why a 6x5.5 wouldnt work as long as you give it time to get moving .
I my electric tony used a 8x8 and has power to spare .
Len
I have the very same motor. I used it with my Stryker flying wing, for which it was designed. It draws about 20 amps on a 6-4, but that was about 10 years ago, when batteries weren't as powerful.
Stick with the 6 inch props. A 6-4 should give you 27-32 oz. thrust. Plus it won't tax the motor too much and you'll get at least 4 minutes wide open.
You can always upgrade to the 6x5.5 if you want.

JMHO,
Terry
Nov 26, 2021, 02:04 PM
Registered User
rcflyer11's Avatar
Thanks for your great input guys. I'll have to experiment with battery size to see if I can get the AUW to something less than 40 oz, and still be able to balance the plane. It would be nice to end up with at least 150 watts-per-lb. -- Randy
Nov 27, 2021, 10:14 AM
Modeling Masochist
Terry Till's Avatar
You could use this motor with the recommended 8x7 on 3S and get what you need.
http://www.highendrc.com/index_eprod...products_id=50
The smaller motor may not have enough grunt for the airplane.
That said, you could always try the smaller motor with 3S 1800 or 3S 2200 and see how it does.
Nov 27, 2021, 09:36 PM
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rcflyer11's Avatar
Thanks Terry. I'd really like to run a 7" prop if possible. Anything larger would have insufficient ground clearance. I thought that if the 2700kv motor runs good on a 6x4 prop, maybe my 2000kv motor could handle a 7x5. I'll check it out on my watt meter. If I can get the AUW down to about 32 oz, the 300 watt motor just may have enough grunt. The plane flew at 40 oz + 4 oz fuel with the K&B 15 RR and heavier radio gear in the 70's. Balance might present issues with smaller lipos. I'll cross that bridge after reconciling the power setup.
Nov 28, 2021, 11:22 AM
Registered User

Prop clearance


Theres almost an inch clearance with an 8x8 on my Prather Tony with the incidence set at 0.
I never bent the landing gear or put larger wheels on to make more clearance
Its all stock
I want to try a 7x9 or 7.5x9 if my electronics can handle it.
It might go faster .
Even with that said the nice part of ele is you dont have to go flat out .
While we test flew it it had no bad habits at slow speed .
It stayed level and never dropped a wing .
With the lighter set up im guessing you will need to move your servos ahead .
My battery is as far forward as i could get it but I moved the servos back a bit to save a small amount of weight .
That was a mistake on my part .

Len
Nov 29, 2021, 10:11 AM
Modeling Masochist
Terry Till's Avatar
What batteries do you have? What batteries do you want to run in this?
Nov 29, 2021, 11:00 AM
Registered User
rcflyer11's Avatar
I'd like to run 3S... probably between 1k-2k mah. I'm not planning continuous WOT.... rather, multi-throttle sport flying. Will install smaller servos and receiver... keeping everything forward. SkyGlas Minnow has a glass fuse and balsa-sheeted foam wing. Probably not many (any) of these around any more.
Nov 29, 2021, 08:04 PM
Modeling Masochist
Terry Till's Avatar
Then stick with the motor you have. I suspect your biggest problem will be getting it to balance- just a guess, as I never tried this.
It might be too much plane for your power system, but again, that's just a guess.
Even at 32 oz, you'd need 300 watts to get the magic 150 watts/lb.
At 3.7 volts under load, you'd need 27 amps on 3S, so 6x5.5 might get you there.
Nothing to do but try
Nov 29, 2021, 11:05 PM
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rcflyer11's Avatar
Thanks Terry.... will definitely give it a shot -- Randy
Dec 23, 2021, 08:19 PM
Registered User
If you end up needing more weight forward the best way of adding id a heavier spinner bolt .
If thats not enough a heavier prop nut if thats not enough a heavier prop washer .
And or a heavier spinner
IMHO .
Try to avoid weights at all cost .
They are always further back you lose the advantage of leverage
Dec 23, 2021, 08:23 PM
Registered User
Kevin does the color weaken the epoxy or how do you do that so it doesn't
Len


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