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13b max sustainable rpm - aircraft use

Old 07-14-03, 09:41 PM
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13b max sustainable rpm - aircraft use


a number of people have used flat piston engines from vw and corvair cars as aircraft engine replacements. the advantages are cost of the engine (a couple thousand rebuilt vs $20k), cost of rebuild kits and cost of fuel ($1.50/gal vs. $5/gal for airplane fuel).

i have already identified a number of issues in using a 13b in an aircraft application, but the main thing i am concerned with is the sustainability of constant high RPM, which peak power is made.

does anyone have thoughts on the max rpm you would want to run a 13b at on a continuous basis?

the ideal scenario in my mind would be a normally aspirated 13b, street ported, with straight pipes from exhaust ports to a straight- through muffler out the bottom of the fuselage.

it may also be possible to get a few psi of free boost by placing the air intake directly behind the prop.

the engine would sit in a reverse orientation with the shaft attached to a gear stepping down the rotation so the target engine speed would be geared to match the optimal speed of the chosen prop (typically 3-5k rpm).

my ultimate goal is an engine weighing less than 375 lb, running on street gas, and making around 180hp reliably. is this realistic with the scenario as described? if not, does anyone have any ideas on a configuration that might meet these specs?

the target plane is a piper cherokee 160.

any information would be greatly appreciated.

best rgds,
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Old 07-14-03, 10:04 PM
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Id talk to the people at http://www.rotaryaviation.com/. They seem to have quite a business going doing what you want to
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Old 07-14-03, 10:56 PM
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180hp is EASILY attainable from a 13b. I'd do a medium sized street port, because the bigger the port, the higher RPM the peak power is. I don't have any experience with the 13b, but my 12a can cruise at 5,000rpm all day long and I'd expect the 13b to be the same.
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Old 07-15-03, 02:27 AM
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target rpm for sustained aircraft use is around 6000-6500 rpm. It has been done by many many people.
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Old 07-15-03, 09:53 AM
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I have seen many kit planes use the 13b in this type of application. as long as the rpm is below 7,000 I don't think you will have any issues. a long runner intake and a nice exhaust would work great. 180hp should be easy. I don't have any direct links but search a group called "plugs up" they have a discussion board on rotary powered airplanes. good luck
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Old 07-15-03, 11:01 AM
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excellent... thanks for the information!!!!!
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Old 07-18-03, 01:15 PM
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how would a 20b hold up in this application...it's not much more than the 13b...compared to the 20k you were talkin' about.
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Old 07-20-03, 02:10 PM
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I would also point you to


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Old 08-02-03, 12:46 AM
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Ditto.. Dave has quite a bit of rotary aviation experience. Thats Atkins I'm talking about
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