stunthanger.com
Engine basics => Engine set up tips => Topic started by: Chuck_Smith on March 04, 2017, 10:24:18 AM
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Wondering what fuel consumption I should figure for a stunt run. I'm going with the K77 but I figure they should be close.
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Wondering what fuel consumption I should figure for a stunt run. I'm going with the K77 but I figure they should be close.
I wouldn't assume that, but a PA75 generally uses around 8-8.5 ounces of 10%, using the definitive setup (David Fitzgerald's).
Brett
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HI Chuck
Most people use 7 7.5 ounces, 98% of most everyone using the PA 75 run under 8 ounces, a few use 8.5 ounces, will depend on plane size/drag and setup you go with, props will also have some effect.
randy
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HI Chuck
Most people use 7 7.5 ounces, 98% of most everyone using the PA 75 run under 8 ounces, a few use 8.5 ounces, will depend on plane size/drag and setup you go with, props will also have some effect.
randy
Thanks Randy,
I'm really looking forward to flying this engine. The carbon fiber pipe is a work of art. Thanks for all the help!
Chuck
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Per Kaz's web site:
I use 10 to 15% nitro 20 to 22% all synthetic oil fuel
I use 230cc(8.1oz) tank for pipe and 180cc(6.4oz) tank for rear muffler.
You can use the same propeller and fuel as for PA75.
Tuned pipe 12.2 x 4.5 to 5.2 3B 9000 to 9600rpm
So far pipe length (plug to #1 baffle) is 455 to 460mm in my case
Rear muffler 12.0 x 5.2 to 6.0 3B 8700 to 9300rpm
Prop for rear muffler should be 0.5inch smaller than the prop for pipe.
You can determine the prop is too big for the engine if rpm increase in air.
Pipe create more power than the rear muffler.
When you use the rear muffler, I recommend "No baffle" muffler.
And It is highly recommended to use muffler pressure.
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I may have issues. The Evolution only has about 6 1/2 inches between the formers. Looks like I may have to build a custom tank to get 8 oz. in there. Ideas?
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Chuck, you're right, build the tank. I have the same situation with the K-77 powered Thunder Gazer that I'm building. I'm planning on having to make it 1.25 deep to get the extra volume (I need to find my notes just to make sure). You should be able to figure the location of the uniflow without too much trouble.
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Tom,
I'm thinking I can utilize the volume between the engine mounts and have plenty of fuel. This would be an easy mod to an existing 6 oz. tank. I just need to build the doghouses and then attach them after creating the openings in the tank. I need to pick up about 4 in.^3.
Sorry, quick sketch and the fuel vent is upside down. :)
Chuck
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hi many buy or make a 7 to 8 ounce metal tank
some add a sump to the 7 oz metal tank ( 5.5 in long)
or some run 8 oz plastic tank plumbed uniflow or Billy uniflow
Randyu