Homemade snowplane 4 stroke motor

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PaulyG

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Feb 20, 2021
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So I'm new here. I've never done a project with a propeller before so I'm kind of learning as I go but I figured I'd ask a question here in hopes to save myself some time and money. So I built a small go kart sized snow plane. I have a 3 blade 42" prop that's rated for 4000rpms. I have a predator 212cc motor. I'm guessing that's not gonna be enough to push this thing. So I was looking at getting either a 13hp predator or would I need the 22hp predator motor? The 13hp is only rated for 3600 rpms where the 22hp is rated at 4000 but I'm wondering if the 13hp would have enough to move it along. The snowplane with me on it and having the 6hp maybe weighs 250 pounds. Any input would be appreciated. Thanks!
 

PaulyG

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Feb 20, 2021
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Its a 42" 3 blade composite prop. Right now I've got 9 degree (I believe) pitch blocks in it. I've also got 8 and 10. As far as speed it would be nice if I could hit at least 30ish mph or Even 20. But Any faster would be awesome too. I am very new to this propeller stuff so I really don't much about them.
 

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TiPi

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Aug 25, 2019
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Peeramon (AUS)
That should be easy enough then: Put the small engine on, take it for a run, record engine rpm and speed (GPS), then we can work out what you need. You might need to change to the lowest angle pitch blocks to get the rpm up above about 3,000 to 3,300rpm
 

HeavyIr0ndad

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Nov 22, 2019
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3
So I'm new here. I've never done a project with a propeller before so I'm kind of learning as I go but I figured I'd ask a question here in hopes to save myself some time and money. So I built a small go kart sized snow plane. I have a 3 blade 42" prop that's rated for 4000rpms. I have a predator 212cc motor. I'm guessing that's not gonna be enough to push this thing. So I was looking at getting either a 13hp predator or would I need the 22hp predator motor? The 13hp is only rated for 3600 rpms where the 22hp is rated at 4000 but I'm wondering if the 13hp would have enough to move it along. The snowplane with me on it and having the 6hp maybe weighs 250 pounds. Any input would be appreciated. Thanks!
I like it! Used auto headers for your frame, shock struts for the pivoting main gear, er, skis, bicycle handlebars & a skull! Very creative & very clever!
BTW, I think changing your prop for higher speed will cost you in acceleration. There are always trade offs, you’ll have to find the balance that suits you.
 

proppastie

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Feb 19, 2012
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NJ
I like it too....what is the tire iron hanging down for?....did you use a 110v core-wire welder?
 

wsimpso1

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Oct 18, 2003
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Saline Michigan
The big issue in calculating speed is how much drag on the snow you have. Prop efficiency will be somewhere around 82-85% , while human and structure have aero drag.

Engine hp*550 ft-lb/hp*eff = (snow drag + aero drag)* speed

Drag in lb, speed in ft/s. Have fun.
 

PaulyG

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Feb 20, 2021
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I like it too....what is the tire iron hanging down for?....did you use a 110v core-wire welder?
There's 2 tore irons now. Foot rests. I'd starting tacking it up with a 110 welder then brought into work now and welded it up solid. That was a few week old pic I'd posted before. Its still not pretty but once I get it moving I'll take care of that.
 

Dana

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Apr 3, 2007
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9,744
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CT, USA
I once took my paramotor out with skis, without the wing. I was intending to fly but the winds were too squirrelly to try something new (i.e. skis). Full throttle into the wind (10-15 kts), I quickly reached a moderate speed and no faster, though I can't put a number to it. With the wind at my back, I quickly reached an alarming speed. A paramotor prop will be optimized for low airspeed, around 20mph or less. This was a 15HP 2-stroke engine with a 49" prop and 2.5:1 redrive, I don't recall the pitch.
 

BBerson

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Dec 16, 2007
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Port Townsend WA
My friend carved a prop for my go cart. I think it was a 2 1/2hp Briggs. Worked surprisingly well.
 

Mcmark

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Sep 24, 2013
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444
Location
Owings, MD
Looks to me like it needs a trailing arm or something for the outriggers. The coilovers soften the ride but won't stop it from bending back if unstoppable meets immoveable.
 

djmcfall

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Oct 18, 2008
Messages
40
Location
Twin Falls, Idaho
This reminds me of my buddy and I making stuff on our ranch, using out of the bone pile. Mini bike, go carts, boats, submarine (yes, underwater sub) and even a bat glider made up from Sears black plastic, bamboo from the carpet store and radiator hose clamps (bat glider plans cost me $5 in 1970). Well done PaulyG!
 
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