FW: [COUPERS-FLYIN] glide and stalls

Tim and Martha Briggs Fri, 26 Nov 2004 08:59:46 -0700

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-----Original Message-----
From: Tim and Martha Briggs [mailto:[EMAIL PROTECTED]
Sent: Friday, November 26, 2004 7:59 AM
To: Ed Burkhead
Subject: RE: [COUPERS-FLYIN] glide and stalls

Ercoupers:

My two cents on all this debate about glide ratios. On my latest BFR, my CFI and I tried glides at 60, 70 and 80 MPH indicated and the shallowest descent rate we could achieve was about 500fpm at 75 IAS. My airspeed indicator is not very accurate so it may have been faster in reality. While I like to study such technical things, I know if I turn into a member of the Ercoupe glider club, I won't be thinking about ratios and calculating my max distance available based on some ratio. While its nice to have a reference speed, the other variables would seem to negate much of the usefulness of a glide ratio. Terrain, winds, visibility, thermals etc.. For me the critical info is how much altitude I have to work with and what is my groundspeed. I generally plan for a worst-case scenario of gliding into a headwind which would reduce my groundspeed to 60 MPH or 1 mile a minute. With 1 minute of flight for each loss of 500 feet altitude, I can glide about 1 mile for each 500 feet of altitude. Knowing this, I can plan accordingly. If I have 2000 feet to work with, I can glide for about 4 miles.

I can't really judge distance accurately in terms of miles anyway, so the bottom line is that I probably won't even be thinking about all this stuff. Rather, I'll be "eyeballing" my landing site and sizing up my glide by visual reference the same way we judge our approach to a runway. I probably will reference my VSI and GPS groundspeed to see how my glide is shaping up. My GPS also has a selectable track vector that shows where you will be in 3 minutes or 6 minutes. If I were trying to glide to an airport or other feature that was on my GPS that would help too.

One man's opinion...

Tim

Erco 415G

N94413

-----Original Message-----
From: Ed Burkhead [mailto:[EMAIL PROTECTED]
Sent: Thursday, November 25, 2004 9:35 PM
To: Coupe-List
Subject: RE: [COUPERS-FLYIN] glide and stalls
----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]----
Cyrus wrote:

Maybe this impression should be modified in the FAQs. 9 or 10 : 1 ratio would be better than a C150.

My problem with the 6:1 glide ratio is that I did careful measurements (albeit with an airspeed indicator with about a 15% error). My computations showed a 12:1 ratio at the best glide speed of 80-85 mph and 8:1 at the worst gliding airspeed of about 63 (bad airspeed indicator). Cut those numbers down by 15% and you sure dont get 6:1 for best ratio.

Id like to see several someones do RIGOROUS glide testing and well work up the data. Anyone interested should contact me and Ill send you a procedure you can use. (If I get time, Ill write up the testing procedure and post it on my website next week).

Ed Burkhead

http://edburkhead.com/

ed -at- edburkheadQQQ.com (change -at- and remove the QQQ)

-----Original Message-----
From: Dr. Cyrus Wood-Thomas [mailto:[EMAIL PROTECTED]
Sent: Wednesday, November 24, 2004 9:45 AM
To: Ercoupe Hangar Flying
Subject: [COUPERS-FLYIN] glide and stalls
 
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Ed said: I do NOT believe the glide ratio (at best glide speed somewhere near 75 mph) is ANYWHERE near 6:1. I'm betting 9:1 or 10:1.
Ed Burkhead

Williams said: At "best glide speed" the coupe has reasonable
glide performance. At "minimum" speed some sink like a rock. William R. Bayne

Cyrus says: thanks for clearing this up guys. from reading the FAQs in the website I got the impression the coupe sank like Lake aircraft (due to the exposed engine up top, the wing floats, heavy weight of construction). But they don't feel like they do. It doesn't make sense that they should have a high sink rate. (besides 'high sink rates' are for people who build expensive kitchens!) Maybe this impression should be modified in the FAQs. 9 or 10 : 1 ratio would be better than a C150.

Why did some planes get modified to have extra back elevator, on a spring loaded resistance device, so that the planes could be stalled? when do you need to stall a coupe? on landing?

Cyrus

Dr. Cyrus Wood-Thomas D.C.
Chiropractic Physician

Diplomate of the National Board of Homeopathic Examiners

Past President of the Chiropractic Academy of Homeopathy

MDH Homeopathy, India

www.angelfire.com/az/CysWebSite

Tel: 928-925-0246 Long distance: 1-800-563-4095
Mailing address: P.O. Box 3248 Prescott, AZ 86302

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FW: [COUPERS-FLYIN] glide and stalls

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