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  #21  
Old 03-18-2017, 08:19 AM
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pierre smith pierre smith is online now
 
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Default Note

I saw this setup at Ray's and all the Van's motor mounts are used. Only the extension is by UL.

Best,
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  #22  
Old 03-18-2017, 08:25 AM
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Quote:
Originally Posted by scsmith View Post
3300 rpm! wow!

Even a 68" prop at takeoff 3300 rpm has a tip mach no. of 0.89!

by comparison, a 72" prop at 2700 rpm has a tip mach no. of 0.77.

This is going to be one very noisy take-off configuration, and prop efficiency will likely be degraded by the shock losses, as well as the smaller diameter. So takeoff and initial climb performance are not going to be like a 200 hp Lycoming.

If you were to put a 72" prop on it and limit the RPM to 2700, it would be 165 hp (assuming a flat torque curve).
At what temp? that .89 Mach # could swing both directions in a big way........
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  #23  
Old 03-18-2017, 10:37 AM
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taverroi taverroi is offline
 
Join Date: Dec 2009
Location: Beaufort South Carolina
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Quote:
Originally Posted by Mlidzct View Post
Looking good! Whats this FWF package going for?

I almost bought this airplane, for those interested in the subaru performance heres a link to a kitplanes article on this airplane.

https://subenews.deej.net/wiki/image...planes0509.pdf

Ray Lawrence 478-232-9560 (the project AC Mech/builder and Engine dealer) will have to address the cost of the FWF package. He will be chiming in here on these postings soon. Its cost effective and way worth it!!

As for the Kit Planes Article on the plane...that was a great read. It is a beautiful build, in every way for sure!. I think I'm lucky to have gotton my hands on it. When Ray did my prebuy on it he called me right away and said "Cut this man a check!" And with this new FWF set up and ALL NEW panel to come its going to be to die for!!! (not literally!!..for the record
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  #24  
Old 03-18-2017, 10:39 AM
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Default Lower Cowl Prefit Pic

Lower Cowl prefit in place..Sooweeet!

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  #25  
Old 03-18-2017, 10:54 AM
rvbuilder2002 rvbuilder2002 is offline
 
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Default Is there any plans to do a spin test program????

Extending the cowl and adding side area that far fwd of the C.G. (not to mention the possibly different moment of inertia from the further fwd engine) can have a noticeable effect on spin recovery properties.........
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  #26  
Old 03-18-2017, 11:00 AM
scsmith scsmith is offline
 
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Quote:
Originally Posted by bret View Post
At what temp? that .89 Mach # could swing both directions in a big way........
Well, it really doesn't change very much. I just used SSD c=1100 ft/s.

If it was 100F, then c = sqrt((460+100)* 1.4 * 1716.5) = 1160.
The rotational tip speed was 979 ft/s, so the tip Mach no would be 0.84.
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  #27  
Old 03-18-2017, 11:07 AM
scsmith scsmith is offline
 
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Quote:
Originally Posted by DanH View Post
From the operating manual...

Maximum (for 5 minutes) : 200 hp @ 3300 Rpm
Maximum continuous power : 180 hp @ 2800 Rpm


...so if you think of it as a 180, and prop it as such, you should be close.

The charts show max torque centered on 2800 RPM.
Thats a good way to look at it. nice package. 50 lbs lighter, smooth running.

I haven't done the math, does a 50-lb lighter engine extended forward 11 inches balance correctly? The engine has a long nose on it, so the c.g. of the engine is probably not a full 11 inches farther forward.

From the pictures, it looks like the intake tubes are on the top (cross-flow head). But I don't see where the intake plenum and throttle body are. Is it on the back?
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  #28  
Old 03-18-2017, 12:28 PM
Chkaharyer99 Chkaharyer99 is offline
 
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Location: Pilot Hill, CA
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What effects could one expect during operation from moving the power plant seven (7) inches forward and the prop eleven (11) inches forward?

Will it be more or less effected by loading weight in the rear baggage area?

How will it effect pitch, roll and yaw?

Can it be expected to be more of less stable?
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Last edited by Chkaharyer99 : 03-18-2017 at 01:41 PM. Reason: Correct numbers to 7 and 11.
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  #29  
Old 03-18-2017, 12:35 PM
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taverroi taverroi is offline
 
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Quote:
Originally Posted by scsmith View Post
Thats a good way to look at it. nice package. 50 lbs lighter, smooth running.

I haven't done the math, does a 50-lb lighter engine extended forward 11 inches balance correctly? The engine has a long nose on it, so the c.g. of the engine is probably not a full 11 inches farther forward.

From the pictures, it looks like the intake tubes are on the top (cross-flow head). But I don't see where the intake plenum and throttle body are. Is it on the back?
Guys,

The engine is actually only mounted 7" further forward and the CG has been engineered to remain exactly in the same location as if a Lycoming had been installed. A lot of work has gone into making this done right the first time.
The same set up has been flying on a Glasair Sportsman for over 400 hrs.
Also it has been flight reviewed and evaluated by Ken Kruger previously of Van's Aircraft who by the way had a large input in the designed the RV8 while employed with Van's Aircraft.
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  #30  
Old 03-18-2017, 02:03 PM
scsmith scsmith is offline
 
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Default cowl cooling flow exit radius

It may be too late now, sorry I couldn't suggest it sooner. But while you are down to a clean firewall, its an excellent time to make a generous radius lower cowl lip where the cooling flow exits.

Consider the radius lip on the RV-8 as a minimum, and go larger if you can. Would need to be integrated into the motormount with the -A model. Maybe actually mount it to the motormount tubes with a small gap to the firewall.
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