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Old 05-21-2018, 09:21 AM
ronschreck's Avatar
ronschreck ronschreck is offline
Join Date: Mar 2006
Location: Gold Hill Airpark (NC25), NC
Posts: 1,363

Originally Posted by precession View Post
My carburetor-equipped engine also stops quickly in zero or negative G. I have a Catto prop (not metal), and it does not keep windmilling beyond anything other than a very brief power interruption while at speed. I also have had it stop and had to crank the starter to get the engine going (after wasting a bunch of altitude learning that diving wasn't doing the trick). I'm not comfortable with that as a normal (or even irregular) practice, and I especially don't think it's a great idea at the lower altitudes you'd fly if in a contest (I've been practicing around 5K.) So I agree with you even about the negative 45 degree down of the 1/2 cuban called for in most primary sequences. I guess if I enter a contest, I'll just do a non-negative roll there and take the deduction rather than risk drawing the straight inverted line and having the engine/prop stop.

I don't think spatsch knows me by name (I'll probably shoot him an email), but I've had the pleasure of meeting him and admiring his airplane, and if I recall correctly (and sandifer now confirms), he has fuel injection. Although I'm the guy asking questions here (and learning a lot from the fantastic replies), I think I can still say, at least in my opinion, that if you have fuel injection, you have the most important part of an "inverted fuel" system.

I think there's a thread somewhere where Ronschreck says he flew his fuel injected RV-8 (without inverted fuel tank w/ flop tube) the length of an airfield inverted without it stumbling. And Spatsch says he can fly a good while while inverted based just on his fuel injection, without the inverted tank or oil system. Which I think shows that of the two parts of an "inverted fuel system" -- (1) being fuel injection/throttle body/pressure carb, and (2) being inverted tank -- the fuel injection is far more important, and you can do a lot with just that.

Based on what Sandifer, and others I've heard, have said, if you have a metal prop the prop will keep windmilling during the brief engine stoppages, so it's apparently no problem. But if you have a wood/composite prop you're in a different situation, especially for example at the top of a hammerhead, where my engine & prop have stopped cold.
You are correct on all points. I produced an EAA Webinar on the subject of equipping your RV for aerobatics and even listed my priorities for doing so. Fuel injection is near the top of the list and inverted fuel is near the bottom. I know that money is often a deciding factor when equipping your airplane for any endeavor so putting money where it will do the most good is important.
Ron Schreck
IAC Director and National Judge
RV-8, "Miss Izzy", 2200+ RV Hours
Track Me *** Gold Hill Airpark (NC25)
VAF 2019 Donor
"Flying is the art of throwing yourself at the ground and missing."
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Old 05-21-2018, 12:15 PM
spatsch spatsch is offline
Join Date: Nov 2014
Location: Randolph, NJ
Posts: 189

Sorry if I confused people with my reply.

I don't consider fuel injection part of an inverted system.... . So for me inverted system means inverted fuel pickup and oil. Hope that explains it.

And yes precession I don't know you by name.

Oliver Spatscheck
RV-8 & J-3
N-2EQ & NC-49762
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Old 05-22-2018, 06:08 AM
precession precession is offline
Join Date: Apr 2006
Posts: 144
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Sent you an email, Spatsch.

Looks like this thread may have just about run it's course, so just wanted to say many thanks to everyone who replied. Read every post carefully, went to every link, watched every video linked (some excellent videos by the way), and received lots of valuable information and advice.

Happy flying to all.
RV-4 in NJ

Last edited by precession : 05-22-2018 at 06:12 AM.
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Old 05-22-2018, 10:41 PM
1flyingyogi 1flyingyogi is offline
Join Date: Dec 2015
Location: Long Beach, CA
Posts: 263

Originally Posted by spatsch View Post
Sorry if I confused people with my reply.

I don't consider fuel injection part of an inverted system.... . So for me inverted system means inverted fuel pickup and oil. Hope that explains it.

And yes precession I don't know you by name.

I see what you mean. In that case, I don't have inverted systems either. Just fuel injection, no flop tube and only a "half" Raven system which is nothing more than a glorified air/ oil separator.

That was a very cool super slow roll, Eric! Maybe a fastback -4 with the bigger fuse side area can do it - barely??
Brian RV4
0-320 AFP fuel injection, EFII Electronic Ignition, Raven 1/2 Oil, Sterba wood prop
Dues Happily Paid
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