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01-12-2009, 06:46 AM
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Join Date: Jan 2006
Location: Dallas, TX (ADS)
Posts: 2,180
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Quote:
Originally Posted by asav8tor
I can remember from college the instructor writing on the chalk board "L/D Max = Max range for a prop airplane no wind."
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I can attest that this also works for airplanes without props  (assuming no thermals, of course).
TODR
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Doug "The Other Doug Reeves" Reeves
CTSW N621CT - SOLD but not forgotten
Home Bases LBX, BZN
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01-12-2009, 07:11 AM
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VAF Moderator / Line Boy
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Join Date: Jan 2005
Location: Dayton, NV
Posts: 12,256
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Totally Impractical, of course.....
I wasn't really thinking in terms of GOING anywhere with this musing...just thought "wouldn't be interesting to take off at sunrise and lope around the local area until the sun set...in summer!
It would be interesting to try it for a little while and see where you actually had to run to keep the engine happy - I suspect it would be closer to L/D max than slow flight, and that would probably be 3.0 gph or so. Still a long time in the air on standard tanks...
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Paul F. Dye
Editor at Large - KITPLANES Magazine
RV-8 - N188PD - "Valkyrie"
RV-6 (By Marriage) - N164MS - "Mikey"
RV-3B - N13PL - "Tsamsiyu"
A&P, EAA Tech Counselor/Flight Advisor
Dayton Valley Airpark (A34)
http://Ironflight.com
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01-12-2009, 07:52 AM
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Join Date: Dec 2004
Location: Southlake, Texas
Posts: 626
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Endurance
Paul,
I spent 4+48 in the Doll Oshkosh WI to Northwest Regional TX with 1+20 remaining at that cruise setting last August.
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Danny King
Beautiful Doll 80434 TT 1675 hours
I0360 A1B6 200 HP
Christen Inverted Oil
First Flight 12 July 2000
VAF Dues current for 2020
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01-12-2009, 09:47 AM
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Join Date: Jan 2005
Location: Houston, TX
Posts: 868
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Quote:
Originally Posted by ronschreck
I was at Sun-n-Fun a few years back and met an RV-8 driver from Kansas. He had extended his wing tanks to the wing tips, virtually doubling his fuel capacity. He told me he could fly, non-stop to anywhere in the continental US. I left after asking him one more question: Why?
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I saw that RV-8 at LOE a few months ago... and while quite impressed with it, I also wondered "why?" myself. I'll admit that an extra 9 gallons (HWA ER tanks) would be nice to have, but 75-80 gallons? Ouch, that hurts to think about that kind of endurance. I'd have to bring along a jumbo sized pee bottle...
My long range "record" was 853nm from Thermal, CA to Junction, TX; took roughly 4+45, had 6 gallons remaining and my butt and bladder were ready for a break. Then again, if I'd had those 9 gallon ER tanks and another piddle pack, winds permitting I could have made Palm Springs to Houston non-stop... tempting.
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John Bixby
RV-8 QB sn 82030 - 1750 hrs
O-360-A1D/CS/Pmags
Houston, TX
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01-12-2009, 10:37 AM
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Join Date: Jan 2005
Posts: 112
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Just because you have fuel for 6 hours plus reserve does not mean you are always going to fly for that time. I found having the wing tip tanks which give an extra 2 hours useful when I fly to places that don't have fuel or have expensive fuel. I can fly back home without having to fill up or divert to a field that has fuel.
I am afraid we have somewhat deviated from the original question on this thread.
Barry
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01-12-2009, 01:36 PM
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Join Date: May 2005
Location: Mesa, AZ
Posts: 209
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Quote:
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I also wondered "why?" myself. I'll admit that an extra 9 gallons (HWA ER tanks) would be nice to have, but 75-80 gallons
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I understand that we are experimental. I just don't think it is that wise to stick that much gas out there. That is a long way from intended design.
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Craig C A&P/IA
Mesa, AZ RV-8 SerNo 82582
Wings/Fuse N18VA Res
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01-12-2009, 02:36 PM
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Join Date: Jan 2008
Location: Ashland, OR
Posts: 2,574
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About 40 hp at best range (L/D) speed
QUOTE=gasman;288864]If you did fly at 80kts level for one hour on one tank that you switched to after you established your cruse, and then switched back for landing and then fueled the cruse tank you would see that you used more like 3 to 4 gallons for that period.
It takes between 55 and 60 HP to keep a 6 or an 8 in the air at 80kts. 12# of fuel /.41=29hp........ But I might be missing something.[/quote]
In round numbers, something close to 40 hp at best range speed.
So that is something like 2.7 - 2.9 gal/hr.
Just imagine how much further you could go with an aspect ratio 6.3 tapered wing!  Power required drops to about 35 hp.
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Steve Smith
Aeronautical Engineer
RV-8 N825RV
IO-360 A1A
WW 200RV
"The Magic Carpet"
Hobbs 625
LS6-15/18W sailplane SOLD
bought my old LS6-A back!! 
VAF donation Jan 2020
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01-13-2009, 06:51 AM
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Join Date: Jan 2005
Location: Louisville, Ga
Posts: 7,840
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Steve...
.....kindly check your PM's,
Regards,
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Pierre Smith
RV-10, 510 TT
RV6A (Sojourner) 180 HP, Catto 3 Bl (502Hrs), gone...and already missed
Air Tractor AT 502B PT 6-15 Sold
Air Tractor 402 PT-6-20 Sold
EAA Flight Advisor/CFI/Tech Counselor
Louisville, Ga
It's never skill or craftsmanship that completes airplanes, it's the will to do so,
Patrick Kenny, EAA 275132
Dues gladly paid!
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01-13-2009, 07:12 AM
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Join Date: Jan 2005
Location: Peachtree City, Ga
Posts: 1,040
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Endurance
Years ago (late 70's), a fellow USAF OV-10 pilot in our squadron had been looking over our performance charts and decided to max endure on a xcountry. He went to max endurance at high altitude and by the time he arrived back at home station, the command post and squadron had a SAR going trying to find the 'overdue' OV-10. Needless to say, he met some interesting people and his career was no longer a happy one! He is now with the FAA!
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Vern Darley
Awarded FAA "The Wright Brothers 'Master Pilot' Award"- for 50 years safe flying
RV-6A N680V / RV-10QB N353RV
Luscombe 8E N2423K 50+years
Hatz Biplane N2423Z soon to be birthed
Falcon RV Squadron Founder
KFFC Hanger D-30
Peachtree City, Ga
770 310-7169
EAA Technical Counselor #5142
EAA Flight Advisor #486336
ATP/CFI/A&P/DAR
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01-13-2009, 07:12 AM
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Join Date: Sep 2005
Location: Maple Grove, MN
Posts: 2,333
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About the lowest fuel consumption I have been able to do maintaining level flight is 3.5 or so, and that is around 100 knots or something like that. I know Pete's 9A will maintain level flight down in the 3 or just below gph range. I will try to get a fuel burn chart developed the next time I fly (probably not today, -23F at my house this morning!). When I make this chart, I will make sure I am at "optimal" economy settings, usually just LOP.
BTW, my airplane will overheat eventually flying level at 80 knots in the summer. The power required is high relative to the cooling air. I'm guessing I need around 4 gph at that speed. The charts will be interesting.
Paul, does your fuel flow meter see pulsed flow? I wonder if that could be fooling it a little. 2 gph does not seem possible. My burn at idle is around 1.3 IIRC.
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Alex Peterson
RV6A N66AP 1700+ hours
KADC, Wadena, MN
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