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Touring Motor Gliders Association (TMGA)

Average Fuel Consumption


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I have heard and seen various numbers. Measurements based on any one fill-up aren't very accurate due to the rather small amounts of fuel involved. Measuring over long periods is more numerically accurate, but also sweeps over many different operating conditions. Still FWIW, in the past 1.5 years, Val Gal swilled 318 gallons of 100LL. There's a fair amount of ground running at my home field, both to get OT up to 50 deg C and a 4,000 foot taxi to the most-used runway. When the master switch is on for in-hangar maintenance, I usually have that Hobbs (airframe time) disconnected. The second Hobbs, switched on by oil pressure, I'll call tach time and includes some A to B cruising and motor-soaring with the engine at idle. And ~ 10% of the time, the noisy fire hazard was off (yay!) Anyway:

Airframe: 100.3 hours --> 3.14 gph

Engine: 90.3 hours --> 3.48 gph

My standard cruise is with coarse pitch and 5,000 rpm. The steam gauge reads ~104 kt, the Dynon, ~98 kt. (?!). After recently fixing some fuel delivery issues and a carb overhaul and balance, my present best guess is that takes 4.0 gph. [Before the fixes, it was as high as 6 gph!]

So right at 30 sm per gallon or better when including TAS. I'm pretty sure that flying at the Carson Speed (1.32 x best glide, clean) of 79 kt, it will eek out 40 mpg.

For this period, $1500 for fuel, $3300 for insurance. 😒

I'd love to hear the experience of others ...

 

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  • 5 months later...

I've done quite a bit of XC in my Ximango (been to the west coast from Tennessee twice, plus other excursions to Florida, NC, SC, OH, and VA). I figure on 4.5 gph. That gives a little fudge factor, but I'm running a little harder at around 5200 rpm in cruise. I see 115 kt pretty regularly up to about 8000'. Above 8000' it definitely slows down. My Ximango is a little different than the others, though. Mine has positive seals on the rudder and elevator, as well as Mylar on the hinge lines, fairings over the wing fold latches, profiled spoiler caps, fitted and sealed gear doors, contoured composite inspection covers replacing the factory flat aluminum plates, and low profile inspection doors on the sump drains. I also tape up the wing fairings. It's noticeably cleaner and quieter than other Ximangos I've flown. I've played a bit with prop pitch, too. There is a sweet spot. 

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  • 1 month later...

115 kt TAS or indicated? If you could be so kind, I'd love to have some pictures and tips for smoothing the airflow around mine, which, as you say, is quite noisy. Pm'd my email ... Thanks!

 

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