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3-blade props fopr Dubb Jett 1.20 ???

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Old 01-09-2005, 01:14 PM
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Crazy4Flight
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Default 3-blade props fopr Dubb Jett 1.20 ???

Well I have the Jett 1.20 just waiting for an airframe, Saturday I bought a GP F-4 project propjet.

now I need a 3-bladed prop to clear the tarmac any ideas?
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Old 01-10-2005, 01:32 AM
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Default RE: 3-blade props fopr Dubb Jett 1.20 ???

Well...

APC has something like a 13.5x13.5- maybe too much pitch unless it was cut down- maybe too much pitch anyway!

MAS has a variety of three blades-like a 14x9 or a 16x10 you could cut down...

Try measuring the clearance, then use Jett's prop recommendation and work down to your clearance

(-1 inch diameter= +1 inch pitch)

Ex: 15x8 = 14x9..............14x9 = 13x10, and so on

This should get you in the zone, but verify using a tach and Jett's numbers for your engine

At any rate, sounds like a lot of fun!

Oh yeah-Don't use a chicken stick! :>(

WW
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Old 01-10-2005, 09:35 AM
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Default RE: 3-blade props fopr Dubb Jett 1.20 ???

The Phantom has ground clearance for a 12" prop - sometimes for a 13" if you fly off a hard surface. I've heard of some people using 14" blades, but I don't know how they managed that.

I'd suggest using an APC 12x12 on the 1.20 to start with. As long as it is the cast case 1.20. It wont mind the RPM
That will give you the best all-around performance, and some good top end speed. If you have room, perhaps go up to a 13" dia prop after that. See which one you like.

For this application try to prop the engine in the 10K to 12K rpm range. A little bit over that is ok too (just pushing the outside of the tuned muffler range).
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Old 01-10-2005, 05:24 PM
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Default RE: 3-blade props fopr Dubb Jett 1.20 ???

Well the box suggested a OS.61 FX for the F-4.[:'(]
I thought it needed a little bit more power.
Yes it will be flying off of pavement.[8D]

Will geta 12x12 and start from there...


now where did I put that shoehorn?????
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Old 01-10-2005, 11:33 PM
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Default RE: 3-blade props fopr Dubb Jett 1.20 ???

Sounds about right--It's a 2-blade prop. APC doesn't make a 12x12 3-blade

Kinda hard to find 3-blades in very many sizes

WW
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Old 01-15-2005, 06:43 PM
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Default RE: 3-blade props fopr Dubb Jett 1.20 ???

well i got out the shoehorn and the Jett 120 in

the GP 40-70 adjustable mount once setfor a supertigre90 has been abused

I will make my own mount out of 6061-T6
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Old 01-15-2005, 07:22 PM
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Default RE: 3-blade props fopr Dubb Jett 1.20 ???

Cool! You ARE going to use an aluminum spinner right?

I would be tempted to leave the fake-intakes off although I know it is an F-4 mortal sin... One easy way to gain prop. clearance is going with bigger wheels even a slightly larger dia. nosewheel will help---

The 1.20 is torquey isn't it? Jett-90L would be good also...
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Old 01-17-2005, 10:54 AM
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Default RE: 3-blade props fopr Dubb Jett 1.20 ???

That looks pretty kewl Does not look out of place at all.

Have you trial fit the muffler? How did that work out ? Any interference issues ?
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Old 01-17-2005, 05:53 PM
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Default RE: 3-blade props fopr Dubb Jett 1.20 ???

muffer clears airframe and nose gear but not by much.

dont have a Jett 90L so i will have to suffer

gear lenght limited and tire size too due to springair retracts
builder of air frame took that into account
( length of strut and tire size he planned a ST.90)
and I should have just enough
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Old 01-17-2005, 07:22 PM
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Default RE: 3-blade props fopr Dubb Jett 1.20 ???

You should have pleanty of clearance for at least a 12" dia prop. You are in good shape.
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Old 01-18-2005, 06:54 PM
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Default RE: 3-blade props fopr Dubb Jett 1.20 ???

made a new motor mount for 1.20 / F-4 ...in 2.5 hours after work

adjustable GP mount 40-70 with a file I did the 1.20 into it but too far forward and holes pattent for ST90 overlapped

just need to move an edge back about 1/16" see red line in photo.
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Old 01-19-2005, 10:03 PM
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Default RE: 3-blade props fopr Dubb Jett 1.20 ???

ok I got the 120 in on the new mount, set the gear in and have 2.25" of clearance with a 12" prop, also the new mount moves the 120 1/4" aft and gave me about 1/8" spinner to cowl clearance. The only close call will be the tire~muffler clearance.
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Old 01-20-2005, 09:53 AM
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Default RE: 3-blade props fopr Dubb Jett 1.20 ???

That looks quite a home in there

what size spinner is that? I forget what size I bought for mine.......
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Old 01-20-2005, 05:01 PM
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Default RE: 3-blade props fopr Dubb Jett 1.20 ???

I dunno it came with the F-4

looks to be a 3" dubro
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