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Glide ratio

Depends on your propeller choice (CS vs Fixed), altitude, airframe cleanliness, speed you descend at (maximum range or minimum descent rate) etc.
A ballpark number is 1nm for every 1,000ft of elevation loss.
Best bet is to go out and take a few measurements and put the results in your POH.
Tom
RV-7
 
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The CAFE foundation did a thorough test of a fixed pitch RV-6A that was published in Sport aviation in 1993. I don't remember which month.

Anyway, I seem to remember the glide ratio was approximately 10:1 at 100 mph.

A fixed pitch RV-7 should be similar.
 
Depends on your propeller choice (CS vs Fixed), weight,
RV-7

While the no-wind speed for maximum glide distance does depend on weight, the actual no-wind glide range, if flown at best speed, is independent of weight. You just get there sooner, if you're heavy.
 
On a related question, what is the optimal speed for best glide ratio? That should be fairly similar for most RV 7s with the same engine.
 
On a related question, what is the optimal speed for best glide ratio? That should be fairly similar for most RV 7s with the same engine.

That depends on the weight, and, in the real world (if you?re concerned with distance covered over the ground), the wind velocity.
 
one thing to consider in my opinion - should you get into the situation that this data may become necessary, such as in an engine failure - it may be impossible to put the prop to coarse pitch as this requires oil pressure... fine pitch
with a windmilling engine results in really poor glide performance. more like 1:8 around 85-92kts...
on the other hand, should the engine seize, the prop factor is yet a completely different animal with improved glide performance expected.
 
one thing to consider in my opinion - should you get into the situation that this data may become necessary, such as in an engine failure - it may be impossible to put the prop to coarse pitch as this requires oil pressure... fine pitch
with a windmilling engine results in really poor glide performance. more like 1:8 around 85-92kts...
on the other hand, should the engine seize, the prop factor is yet a completely different animal with improved glide performance expected.

I?d be reasonably confident that the windmilling prop after engine failure would generate sufficient oil pressure to allow the prop governor to produce a fully coarse pitch. At least it did on my C182 after I deliberately killed the engine with mixture to ICO. And as you stated if the engine fails catastrophically and seizes then the stationary prop would probably produce an even better glide.
 
having had the unfortunate experience of a con rod failure on the O-320 of my Falco Series III many moons ago, I experienced a very high descent rate at best glide... no control on the prop since all the oil was dumped thru holes on the top and bottom of the crankcase.

Better plan for the worst case and also train for that attitude change between engine on initial climb and engine out a split second later...
 
I?d be reasonably confident that the windmilling prop after engine failure would generate sufficient oil pressure to allow the prop governor to produce a fully coarse pitch.

agreed. that is assuming there is still oil in the system...
but consider a gradual oil pressure loss / oil leak and a shutdown short of a seizure e.g. possibly intentional to save the engine. that will still produce windmilling but without fluid to push the prop...
 
Last night I was doing my BFR, my instructor was surprised at the glide ratio. On approach into KSNA, she ask if we could glide to the airport. I was 2.4 nm from the threshold at 1160 feet agl with a 7 knot headwind (just looked at the datalog). We made it with 10 feet to spare. That is a 11.9:1 glide ratio.

What a great plane! An RV-7 with a three-blade Catto fixed pitch prop. Best glide at mid weight is 80 KIAS.
 
From my experience that glide ratio may be a little optimistic since the engine is running and probably putting out some thrust. When you shut down the engine and stop the prop it may not be as good. I did an engine and prop stopped on my 12 at best glide speed of 60 knots and got 10.3:1, less than the generally recognized ratio of 13:1. The 12 wing airfoil should be more efficient in glide than the 7.

Since I just finished a 7A I am interested in any real numbers. Reviews of others POH charts shows glide ranges of about 1 nm per 1000' for a ratio of 6.4-7.2:1 depending upon the prop position.
 
From my experience that glide ratio may be a little optimistic since the engine is running and probably putting out some thrust.

I just looked at the datalog. The engine was turning between 950 to 1050 rpm which is higher than my idle speed (about 700) so I assume the engine was being backdriven. So I would expect my drag to be higher than a stopped prop, but lower than a windmilling prop.
 
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