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Old Oct 14, 2007, 05:19 PM
Dance the skies...
Tom Frank's Avatar
United States, MA, Walpole
Joined Dec 2003
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ATIS, If you refer back to Kensp's motor test chart, switching from the 3-blade to the 2-blade GWS 10x6 DD prop will gain you about 5 mph in pitch speed while saving about 1.5 amps at WOT. You do lose thrust in the process, but I think will be a better motor/prop combo in the air.

Do you happen to have a pic of your cowl damage you could post? I'm curious where the cowl split. I did not cut out any of the center lower air scoop, and drilled holes in the other two on the side just above. I have an idea for beefing up this lower front with minimal weight, but knowing the failure points would help.

I was careful not to land without being under low power, so I was able to just barely fly in parallel to the ground, then cut power and add a bit of up elevator to flare just before touchdown. I've only flown the two initial flights, but both times I had enough airspeed such that the flare actually caused me to gain about a foot of altitude and then drop in. Neither time resulted in any cowl damage, though. Sooner or later I'll bump the nose cowl, I'm sure, so want to beef it up a little.

p.s. That's wierd about your spinner... mine has the same OD as the circular part of the cowl, and I got mine from Epyaya, too (one of the very first they received).
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Old Oct 14, 2007, 05:50 PM
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Tom

It appears that the three blade 10 x 6 propeller unloads a lot more in the air and so the top flying speed of the two and three blade props is very similar.

Ken
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Old Oct 14, 2007, 06:23 PM
Dance the skies...
Tom Frank's Avatar
United States, MA, Walpole
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Quote:
Originally Posted by kensp
Tom

It appears that the three blade 10 x 6 propeller unloads a lot more in the air and so the top flying speed of the two and three blade props is very similar.

Ken
That's interesting... with identical blade size and shape, I'd have guessed the 2 blader would spin faster producing a noticeably greater amount of pitch speed. Which do you prefer? Which pulls the best in large vertical uplines?
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Old Oct 14, 2007, 06:56 PM
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Quote:
Originally Posted by brati4
Roger that and watch the cowling.... Winds are dead... so I guess this is it.
Got to the field.... Kids are playing and then the wind started blowing.. Not meant to be today..

Tom: What is your fix for the cowling? How do you plan to reinforce it???
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Old Oct 14, 2007, 07:03 PM
Dance the skies...
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Quote:
Originally Posted by brati4
Got to the field.... Kids are playing and then the wind started blowing.. Not meant to be today..

Tom: What is your fix for the cowling? How do you plan to reinforce it???
I'm waiting to more infor from ATIS on where the cowl split, but my first thought is to put a 1/16 balsa or ply bulkhead horizontally across the bottom of thw cowl just above the bottom air scoop indentation. The fill the void below the bulkhead either with highly foamed Gorilla glue or inject some of that foam used for filling gaps around doors/windows, etc. That would give a solid impact area if the remaining cowl can take the load. Might also require gluing some stiffeners inside the cowl where the snap pins protrude through since much of the impact load will be transferred to thes pins. May not help that much in a major header, but if it can prevent indentation and splitting on some routine less-than-perfect grass landings it will have met my intent. Needs to be kept light, though.
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Old Oct 14, 2007, 07:10 PM
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Tom: copy that on keeping it light.. What's your feel on thin fiberglass cloth???
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Old Oct 14, 2007, 07:35 PM
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Tom,

Sorry no picts as I taped it up already...

it broke/cracked along the bottom center and spidered up the left side; the right side just below the lower cowling clip going down and to the front; and of course, the entire cowling moved up (popped off the clips) destroying the shark teeth... a little tip would be to cut the decal along the cowlings edge so when you do bump it it wont destroy the entire decal... I also only cut out a little of the lower center and a very small area on the two side but it didnt help... well maybe it did I guess it could have been worse.
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Old Oct 14, 2007, 08:11 PM
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Some suggestions here:

ATIS don't throw the damaged cowling away. Buy a new one. Cut out the front part of the damaged one about 1 inch from the front. Never mind the crack. Push the damaged ring into the new one at the back and glue them together with PU glue. That makes the front part of the new one much stronger and more importantly, with the filled PU glue, not so bittle. Don't forget to rough up the contact surface before applying the glue.

Optionally, you may also like to apply a glass of 2 Oz fibre glass cloth on the outside. Don't do it on the inside. I tried that and it doesn't work.

It works for my F4U. Hope it work (or least improve) for the P40
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Old Oct 14, 2007, 08:15 PM
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cmpang: What's your suggestion for those of us who have'nt cracked a cowl yet?? What's PU glue??
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Old Oct 14, 2007, 08:56 PM
Dance the skies...
Tom Frank's Avatar
United States, MA, Walpole
Joined Dec 2003
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Quote:
Originally Posted by brati4
Tom: copy that on keeping it light.. What's your feel on thin fiberglass cloth???
I've never used fiberglas, but know some folks who have. They claim it's very strong, but I don't know about the weight.
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Old Oct 14, 2007, 09:00 PM
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Tom:cmpang has got something there regarding using an old cowl to shore up the weak spots. I have an old PZ Spitfire cowl that I can trim to fit the bottom of the GWS cowl. Only thing is: What is PU glue?
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Old Oct 15, 2007, 06:16 AM
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Ok Gents,

Video posted of the maiden... nothing special but it does show the hard left turn on take off (even with a hand launch) and the tip stall on landing...

www.myspace.com/rcihcc

also a video of a ME 262 with duel pusher props
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Old Oct 15, 2007, 08:02 AM
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Looks to me as if it's just underpowered. A stronger motor would have pulled her on t/o and it would be able to keep speed up on landing. IMHO. Atis: I take it with the Park 480, I shouldn't have a problem.
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Old Oct 15, 2007, 08:08 AM
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just remember your nose is going to be heavier.... by about 20 grams....
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Old Oct 15, 2007, 08:36 AM
Dance the skies...
Tom Frank's Avatar
United States, MA, Walpole
Joined Dec 2003
17,187 Posts
Quote:
Originally Posted by ATIS
Ok Gents,

Video posted of the maiden... nothing special but it does some the hard left turn on take off (even with a hand launch) and the tip stall on landing...

www.myspace.com/rcihcc

also a video of a ME 262 with duel pusher props
Ouch! That was a pretty steep nose dig!
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