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estimating fuel time?

Old 09-24-2010, 03:12 PM
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ceecrb1
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Default estimating fuel time?

Whats the best way to estimate the flight time of a new plane/engine/tank combination before ending up with none in the air?

does someone have any tricks


dont see hte point of running it a full throttle on the ground with a timer as we dont fly like that.......
Old 09-24-2010, 03:16 PM
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SMOKEFAN
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Default RE: estimating fuel time?

Fly it for 5min and bring it down and check level.

Deadstick landing are fun. Start making them a part of your flight routine
Old 09-24-2010, 03:24 PM
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Default RE: estimating fuel time?

yeah i do "practice" deadsticks by reducing the throttle and leaving it there... gives you the chance to power up again if you fart it up.
Old 09-24-2010, 03:39 PM
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Default RE: estimating fuel time?

I do the full throttle run on the ground and time it....now I don't fly that way of course....but once the timer goes off I know I'm getting low and have a reserve for a go around or a holding pattern if I need to
Old 09-24-2010, 03:43 PM
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ArcticCatRider
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Default RE: estimating fuel time?

The point of running on the ground until empty is perfect. Since you know you don't fly like that, you'll never have to worry about running out of fuel before the stopwatch starts beeping .

This is the easiest and most effective way to figure this out, short of having a flow meter, or a graduated cylinder or a scale to measure what's left in the tank.
Old 09-24-2010, 03:45 PM
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Default RE: estimating fuel time?


ORIGINAL: SMOKEFAN

Fly it for 5min and bring it down and check level.
That's what I do, fly it for a few minutes, check the level, figure out how long a full tank would go, and then subtract off some time for margin. I rarely set my timers for longer than 10-12 minutes though, I usually want a break after that. Alternatively, you can run it full throttle on the bench for a few minutes (or run it out), and figure out how long a full tank would run. Basing the time on the full-throttle fuel consumption is best, since that would be worst case. If you base max flight time on casual flight fuel consumption, then if you ever fly full throttle most of the time, you may find yourself out of fuel. I typically have 1/4 to 1/3 of my tank left after a flight. One plane has an unusually large tank in it (because that's all I had at the time, and it fit in the plane) so I typically have even more after a 10-12 minute flight.
Old 09-24-2010, 03:48 PM
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Charlie P.
 
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Default RE: estimating fuel time?

Yep.  Ground run at 75% throttle or higher.  Remove the cowl if so equipped so it doesn't overheat.  But remember the air time may be less because of drag and a klunk that sucks air in different attitudes.  I like to leave three or four minutes in case someone splats in the runway or other complications keep you up longer . . . or your consumption is higher for whatever reason.

PS - the advantage of a hand pump is that you know how many revolutions you put in initially and then to refuel (or defuel) so you can calculate fuel usage vs. time in the air.
Old 09-24-2010, 04:00 PM
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Default RE: estimating fuel time?

The problem with running it on the ground is it doesnt get vertical load and it's not real world unless you fly around in a level circle all the time and do not do any arobatics at all. You could be a much as 2-3 mins off if you fly hard or do alot of arobatics.
Old 09-24-2010, 05:14 PM
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Default RE: estimating fuel time?


ORIGINAL: SMOKEFAN

Fly it for 5min and bring it down and check level.

Deadstick landing are fun. Start making them a part of your flight routine
same here. running on the ground and running in the air is much different.
Old 09-24-2010, 07:57 PM
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Gray Beard
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Default RE: estimating fuel time?

I just figure about one ounce per minute, haven't gone wrong yet. After I fly for 10 minutes my timer goes off and I land and see what I have left in the tank then set the timer to what it really gets. That way I'm set to fly in the real world.
Old 09-24-2010, 10:54 PM
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Default RE: estimating fuel time?

I always use geared manual pumps as in the picture. Normal pattern is to count the cranks going in and simply counting the cranks going out after a flight. It soon gives you an indicator to your real fuel consumption and just how long you can fly.

I don,t use timers, the timer in my head does pretty darn good and its easy to figure your duration counting cranks.

John
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Old 09-25-2010, 08:30 AM
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Default RE: estimating fuel time?

ORIGINAL: SMOKEFAN

The problem with running it on the ground is it doesnt get vertical load and it's not real world unless you fly around in a level circle all the time and do not do any arobatics at all. You could be a much as 2-3 mins off if you fly hard or do alot of arobatics.
Running on the ground, with the plane static, is worst case. While your flying, you have forward motion and the prop loading is less than the static case. So yes, running on the ground may give you a little less run time, but that just means you've factored in a little more margin.
Old 09-25-2010, 09:09 AM
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flythesky
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Default RE: estimating fuel time?

I've got an electric pump and time the fill time (count the seconds), fly for a short time (five minutes), land, and time the fill up time again. I've now got a general idea of fuel consumption. I increase flying time until I have maybe 20% difference in fill and refill time. In most cases that's around a 10 minute flight.
Old 09-25-2010, 01:18 PM
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Default RE: estimating fuel time?

Fly it till it runs out !!! Then your sure. ENJOY !!! RED
Old 09-25-2010, 01:19 PM
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Default RE: estimating fuel time?

My problem is that i´ve gotten used to my Extra 300, which when you remove the canopy, has the fuel tank extremely visible.. so its so easy to just SEE what i´m doing.. this new plane the tank is well hidden inside and I can only get a view of it if I unscrew the wings every time..

well tomorrow it will maiden.. i´ve changed fuel brand (mostly cause i´ve changed LFS, the last guy was useless, never had anything in stock.) so will take the oportunity of checking the needles/mixes on the ground as a chance to time a tank at least..
Old 09-25-2010, 02:48 PM
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Default RE: estimating fuel time?

Yep, most profile planes and helis make it easy too, just do a slow fly-by and look at the fuel level. I set my timer on one of my profiles for 10min, but ended up flying it about 20min one time, checking fuel levels every so often. With hidden tanks, you just have to rely on your timer.
Old 09-25-2010, 02:53 PM
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Default RE: estimating fuel time?

One once per minute per cubic inch at WOT. If the engine is broken in. Figure 80% of that if you are running rich for break in.

David
Old 09-25-2010, 02:58 PM
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Default RE: estimating fuel time?

I like the way Red thinks!!
Old 09-25-2010, 06:26 PM
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Default RE: estimating fuel time?

This is just a ball park figure but I have the YS stats in front of me and they figure there fuel consumption at: YS .63 1/2ozper minute, YS .91FZ 1.1oz per minute, the 1.40L 1.5oz par minute and the 1.40DZ at 1.75 oz per minute. With these high performance engines you can get an idea of the fuel consumption, I tend to get a bit better even with my YS engines. Fly, land and look.
Old 09-25-2010, 06:42 PM
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Default RE: estimating fuel time?


ORIGINAL: daveopam

One once per minute per cubic inch at WOT. If the engine is broken in. Figure 80% of that if you are running rich for break in.

David
i wish that stood true for all engines.....................this one sucks around 2.75 ounces per minute...(.56cu).............gives me about a 2.5 minute flight time with the 8 oz tank which is all i can stuff into the plane
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Old 09-25-2010, 07:33 PM
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Default RE: estimating fuel time?

I can fly about18 minutes of aerobaticsand have some left with my 34cc gasoline engine and the 420cc tank. That's 14 ounces, or 0.75 ounces per minute of actual flight, with a model that weighs over 15 pounds, using a fuel that costs 1/4 as much as glow alcohol.

Gotta love gasoline birds.
Old 09-25-2010, 09:10 PM
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Default RE: estimating fuel time?

When my timer in my head goes off, I just climb up a bit and fly around till I dont see any smoke trail. Then I land. Easy.... Scoot
Old 09-25-2010, 09:32 PM
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Default RE: estimating fuel time?


ORIGINAL: Charlie P.

I can fly about 18 minutes of aerobatics and have some left with my 34cc gasoline engine and the 420cc tank. That's 14 ounces, or 0.75 ounces per minute of actual flight, with a model that weighs over 15 pounds, using a fuel that costs 1/4 as much as glow alcohol.

Gotta love gasoline birds.
yep Charlie, you got that right, and i'm looking into a gas bird these days.
Old 09-25-2010, 10:07 PM
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Default RE: estimating fuel time?


ORIGINAL: Charlie P.

I can fly about 18 minutes of aerobatics and have some left with my 34cc gasoline engine and the 420cc tank. That's 14 ounces, or 0.75 ounces per minute of actual flight, with a model that weighs over 15 pounds, using a fuel that costs 1/4 as much as glow alcohol.

Gotta love gasoline birds.
When I think of gas I think of my brush cutter, when it finally ran out of gas I would takes a much needed smoke break and have a barleypop. When the throttle broke on my G-62 and went to WOT it was just way more flying then I wanted to do, that was with a 22oz tank. When I worked on sand rails and we would set one up for alcohol I had to open the jets 3 times bigger and those cars were always in need of a fuel station. A lot of good things to say about going gas. I like seeing them starting to come out with some of these new small gas engines. At the prices of glow fuel gas just makes sense. I have several of them but nothing small enough for a 60 size plane.
Old 09-26-2010, 12:15 AM
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Default RE: estimating fuel time?

I have a friend with a 3600.00 plane a DA200- 3000.00 and a 1600.00 in radio gear and servos......Thats alot of Glow fuel right there. Plus I only have room for 40 size planes. He has a dang auto shop that he stores his 80,000.00 worth of planes in

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