Increasing an airplane's range

Capt.Crash'n'Burn

Capt.Crash'n'Burn

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Capt.Crash'n'Burn
OK, lets say that I'm an FAA official who can wave a magic wand and grant STC's for whatever you want.

What would you do to extend the range of your bird besides turn it into a flying gas tank??

Would more horsepower to lift more fuel defeat the purpose, since you now have higher fuel burn rates??

Would you just put on bigger wings or something??

Would you plop down a million bucks and hire Burt Rutan??
 
New engine; fuel injected, 300hp. Get me there faster so there wouldn't be a need for onboard potty.
 
In my aircraft.

Slowing down adds 50nm.
and
Dry tanking the left tank in straight and level flight adds another 50nm because I can burn the 5 gallons of unusable fuel.

I almost always dry tank. I almost never slow down. ;)
 
Typically, the answer is to put more fuel in. In the Aztec I can get the long range tanks, adds roughly another 50 gallons.

While I'd like to do that, there's only one time I can think of when it's really caused me to have to deviate out of my way, and that was flying from Cozumel to Colorado. Because I plan for roughly 600 nm legs, we went to New Orleans instead of the long way across the Gulf to Corpus. It did add to the trip, but not enough to cover the cost of adding the long range fuel. :)
 
In the 172RG and almost any aircraft slow down and fly lower or fly higher.

At 10,000 feet reducing from full throttle <=75% power to 45% power adds about 65 nm. The same reduction at 4000 feet doubles that to 130 nm difference.

At full throttle <= 75% power climbing from 4000 feet to 10000 feet adds 40 NM at 45% power flying higher reduces the range.

Using the same power range my endurance profile is from 5.5 to 8.5 hours. I can add Tip tanks with 24 gallons at a cost of ~200 lbs for an additional 35% or 7.5 to 11.5 hours endurance.

At that point the toilet option is becoming mandatory.
 
Ted DuPuis said:
Typically, the answer is to put more fuel in. In the Aztec I can get the long range tanks, adds roughly another 50 gallons.

It did add to the trip, but not enough to cover the cost of adding the long range fuel. :)
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The big thing that the Metco Tip tanks do for me is allow me to shop for fuel. Over the past 2 years, not being forced to buy $6 fuel or to make an extra fuel stop has saved me enough to pay for the tanks. I bought them used, (1 new/unused) refurbed them myself. They cost me about 1/2 of new installed.

I know of one Aztec pilot that has on occasion removed the rear bench seat, and mounted an RV potty to the seat rails for long trips.

Other than that, O2. It allows you to fly higher and gives you more options wrt winds.
 
My apologies. Byington calls it Vlrc (anything within a 99% of the peak of the graph), CAFE foundation call it Vz. http://www.db.erau.edu/research/cruise/piston.frame.html , go tothe left hand "range vs. speed" link, figure 4.

It's very slow. I have mine placarded "Vlrc=124 knots at 15,000 and down low it's even slower. I'd have to go look at the placard.
 
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Capt.Crash'n'Burn said:
OK, lets say that I'm an FAA official who can wave a magic wand and grant STC's for whatever you want.

What would you do to extend the range of your bird besides turn it into a flying gas tank??

Would more horsepower to lift more fuel defeat the purpose, since you now have higher fuel burn rates??

Would you just put on bigger wings or something??

Would you plop down a million bucks and hire Burt Rutan??
Click to expand...

I wouldnt need an STC just to fly at maximum endurance speed.

Drag increases exponentially with speed. So.. if you want to increase your range, pull the throttle back. At some point you find the sweet spot. Notice this usually does not mean getting there FASTER.. just getting there on one fuel tank (which when factoring in time on refuel stops can mean overall a quicker trip)

Adding fuel will help. Adding power usually does not. Any kind of drag reducing/lift enhancing STC's can be beneficial.
 
Anyone contemplating a performance-enhancement STC should understand the testing and proof necessary to obtain FAA approval. If you still believe their claims, ask them to provide a money-back guarantee.

Doggtyred said:
I wouldnt need an STC just to fly at maximum endurance speed.

Drag increases exponentially with speed. So.. if you want to increase your range, pull the throttle back. At some point you find the sweet spot. Notice this usually does not mean getting there FASTER.. just getting there on one fuel tank (which when factoring in time on refuel stops can mean overall a quicker trip)

Adding fuel will help. Adding power usually does not. Any kind of drag reducing/lift enhancing STC's can be beneficial.
Click to expand...
 
Jim Burns said:
The big thing that the Metco Tip tanks do for me is allow me to shop for fuel. Over the past 2 years, not being forced to buy $6 fuel or to make an extra fuel stop has saved me enough to pay for the tanks. I bought them used, (1 new/unused) refurbed them myself. They cost me about 1/2 of new installed.
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I would definitely go for it if I found a deal like that, and I see the fuel shopping as being a big advantage. There have been times when I've thought about it, but most of my trips the fuel is roughly the same. Still, more options are more better.

I know of one Aztec pilot that has on occasion removed the rear bench seat, and mounted an RV potty to the seat rails for long trips.
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I'd have to get a fire hydrant. ;)

Other than that, O2. It allows you to fly higher and gives you more options wrt winds.
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Agreed. Having O2 has been very nice in winter. I built my system for about $200 total with a really big tank.
 
RMCN172RG said:
In the 172RG and almost any aircraft slow down and fly lower or fly higher.

At 10,000 feet reducing from full throttle <=75% power to 45% power adds about 65 nm. The same reduction at 4000 feet doubles that to 130 nm difference.

At full throttle <= 75% power climbing from 4000 feet to 10000 feet adds 40 NM at 45% power flying higher reduces the range.

Using the same power range my endurance profile is from 5.5 to 8.5 hours. I can add Tip tanks with 24 gallons at a cost of ~200 lbs for an additional 35% or 7.5 to 11.5 hours endurance.

At that point the toilet option is becoming mandatory.
Click to expand...

So am I understanding this correct, flying at higher altitude only saves gas at higher power levels?
 
Doggtyred said:
I wouldnt need an STC just to fly at maximum endurance speed.

Drag increases exponentially with speed. So.. if you want to increase your range, pull the throttle back. At some point you find the sweet spot. Notice this usually does not mean getting there FASTER.. just getting there on one fuel tank (which when factoring in time on refuel stops can mean overall a quicker trip)

Adding fuel will help. Adding power usually does not. Any kind of drag reducing/lift enhancing STC's can be beneficial.
Click to expand...

So I take it, a more aerodynamic wing, with more lift and less horsepower is what you're shooting for??
 
Capt.Crash'n'Burn said:
So I take it, a more aerodynamic wing, with more lift and less horsepower is what you're shooting for??
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Not so much more lift as a higher coefficient of lift (probably what you meant, I'm just using the aero-engineering terms). The easiest way to get a high coefficient of lift w/o redesigning the airfoil is to simply increase the wingspan. Gliders have very high aspect ratios, because long skinny wings have a high coefficient of lift an a low coefficient of drag. Therefore they provide a good L/D ratio.

The speed for your best L/D (and greatest range) is going to be very close to your best glide speed. So throttle back and you'll get the most distance. The problem with this though is it may not be cheaper.

I found on the Cherokee Six that it is almost a wash flying at 75% or 55%. Flying at 55% burns less fuel and extends the range a bit, but the extra time in the air costs money too. Each hour on the tachometer has a cost which offset the fuel savings.
 
Remember also that when you slow down to long range cruise that you should also consider the wind. It's better to have a faster TAS with a headwind and slower one with a tailwind. In an extreme case, if your normal cruise is 125 knots and your long range cruise is 100 knots and you have a 100 knot headwind, if you slow down to long range cruise you will never get there.
 
Me too. With 95 gal capacity, I can fly many trips with minimal fuel purchases at high-priced airports. Even more importantly, base fuel price here is almost $6. Forty miles away, it's $3.xx. So on the way out or on the way back home, it's "Hellooo, self-serve."

Jim Burns said:
The big thing that the Metco Tip tanks do for me is allow me to shop for fuel. Over the past 2 years, not being forced to buy $6 fuel or to make an extra fuel stop has saved me enough to pay for the tanks. I bought them used, (1 new/unused) refurbed them myself. They cost me about 1/2 of new installed.

I know of one Aztec pilot that has on occasion removed the rear bench seat, and mounted an RV potty to the seat rails for long trips.

Other than that, O2. It allows you to fly higher and gives you more options wrt winds.
Click to expand...
 
RMCN172RG said:
According to the POH for the 172 RG Higher altitude improves performance at high power while higher altitude decreases range and endurance at low power. However low power is still better than high power across the board.

http://williams.best.vwh.net/172RG_POH/5-24.html

http://williams.best.vwh.net/172RG_POH/5-26.html
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That's pretty interesting. Now does this apply to all airplanes as well, or just to some?

Is this some kind of universal principle of physics, or just the result of perticular charachteristics?
 
Capt.Crash'n'Burn said:
That's pretty interesting. Now does this apply to all airplanes as well, or just to some?

Is this some kind of universal principle of physics, or just the result of perticular charachteristics?
Click to expand...


The charts are pretty similar in the 172S and 172R POH copies I have available. But then they are all the same basic aircraft.
 
COFlyBoy said:
Not so much more lift as a higher coefficient of lift (probably what you meant, I'm just using the aero-engineering terms). The easiest way to get a high coefficient of lift w/o redesigning the airfoil is to simply increase the wingspan. Gliders have very high aspect ratios, because long skinny wings have a high coefficient of lift an a low coefficient of drag. Therefore they provide a good L/D ratio.
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That's what I was thinking. If you could redesign the wing a bit more like a glider wing, then fill those wings with fuel, you could stretch the range out by a ton.

BTW, I was looking at the Extra Flugzeugbau EA-400. The advertized range is 2,100 NM!!!:hairraise:

EDIT: the range is slightly over 1,000 nm. Damn wiki errors!!
 
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