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Maximizing range on an IO-540

pierre smith

pierre smith

Well Known Member
Jenny and I want to fly to Bermuda, from Charleston, S.C almost a direct route. I have the standard 60 gallon tanks but at my usual power settings, yields an 800 mile range. Bermuda is 765 miles offshore.

I seem to recall when flying with Don at Airflow that at 8,000' he turned my RPMs down to 2100 and WOT, I was burning close to 10 GPH at 160 MPH true, and if memory serves, the Dynon showed a 1200 miles range. That would work with adequate fuel reserves.

How do some of you IO-540 drivers increase range?

Thanks,
 
pierre smith said:
I seem to recall when flying with Don at Airflow that at 8,000' he turned my RPMs down to 2100 and WOT, I was burning close to 10 GPH at 160 MPH true, and if memory serves, the Dynon showed a 1200 miles range.
Click to expand...

Yep.

Here is what we did a few years back, 2300 rpm, 9.5 gph, 13.5 altitude. Note the range, and half tanks left.

DSC06106.jpg
 
i think you should consider the flight back to be the bigger challenge, as you will almost certainly have a headwind

an Aux tank would be a requirement for me if I were doing that flight.

I have a 19.5gallon fuel cell/bladder you are welcome to borrow if you want to plumb it up for this excursion, it has never been used before. I'd sell it too if you wanted to go that route, I believe I paid around $450 for it, to use with my RV-4 that I have since sold
 
Vero

I have SafeAir1 ER Tanks .. gives an extra hour or so ... might be a bit on the edge .. for the installation cost, you might be able to find aux tanks with extra capacity - like 15 a side - talk to Jesse Saint.

Otherwise, fly to Vero, fuel & make the jump. :)
 
All I can say is you got #alls to fly that RV to Bermuda. Don't go during winter or close to that time frame. Been thru there many times in a sailboat. Keep us posted on your plans.
 
Fly high

Pierre, Unless the headwinds are significant, a flight of that distance should be no problem in an RV-10 with 60 gal. fuel. If possible, fly high, and if not, drop down low and use moderate cruise power. Here is a screen shot from our recent trip from Yellowstone back home to Pennsylvania, crossing Lake Erie at 13,500'.



Note that the MPG shown on the Garmin is statue miles and based on ground speed. True airspeed, of course, is knots. I've repeatedly verified the true airspeed with four way GPS runs, and find that it reads about 1.5 mph slow at 8000'. :)
 
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Bermuda

This is not directed at Pierre, but at all the subsequent posts.
From Skyvector.com:
TXKF(Bermuda)
Fuel: jet A
Transient: none
Storage (blank), this to me means no hangar, no tiedowns, no GA parking for small aircraft.

REPEAT: THERE IS NO AVGAS AVAILABLE IN BERMUDA
Bermuda has a reputation of not accommodating GA aircraft unless it is Mr Blumenthals Boeing 727
 
I believe Pierre is the only one here thinking of a flight to Bermuda, but thanks for the information anyway. ;)

jrs14855 said:
This is not directed at Pierre, but at all the subsequent posts.
From Skyvector.com:
TXKF(Bermuda)
Fuel: jet A
Transient: none
Storage (blank), this to me means no hangar, no tiedowns, no GA parking for small aircraft.

REPEAT: THERE IS NO AVGAS AVAILABLE IN BERMUDA
Bermuda has a reputation of not accommodating GA aircraft unless it is Mr Blumenthals Boeing 727
Click to expand...
 
If the airplane can function on zero-ethanol gas, there may be the option either on land or from a marina. Pre-planning diligence and all of that.
 
Back to OP:

2 people on board, I climb to somewhere near 10,000' (choose based on required altitude by direction, plus winds aloft). About 12 minutes, 4 gallons, 20 nm. Add 1 gallon for taxi/start.
WOT, 2250 RPM, leaned to LOP 9.8 (call it 10) gal/hr, 160 KTAS.
5 hours = 800 nm, plus the 20 during climb, = 820 nm, no wind. Leaves 5 gal on board = 30 minutes.

Personally I never cut it that close, I try to always land with 1 hour of gas on board. So 740 nm, no wind, is my limit. For an over water flight like that I'd want even more margin in case we picked up a headwind.
 
Bob, you brought up an important point--------fuel used in climb and its effect on overall range.

The low----9.5 to 10 cruise figures I, Andy, and Pierre mentioned are just that--------cruise.

Thanks for keeping us honest.............
 
Mike S said:
Bob, you brought up an important point--------fuel used in climb and its effect on overall range.

The low----9.5 to 10 cruise figures I, Andy, and Pierre mentioned are just that--------cruise.

Thanks for keeping us honest.............
Click to expand...

Well, I cheated a bit - note the 'two person' qualifier. Loaded to 2700 lbs I lose just a few knots in cruise, but the time to climb increases by quite a bit.
OTOH I didn't count the fuel savings on descent - I can glide almost 20 nm with the engine off! I just count that as part of the reserve.

I think the range can be increased further by slowing down more, maybe around 45% power. But who owns an RV to go slow?
 
Lower RPM = greater fuel economy

I don't have my numbers here, but I did different runs at the same altitude (6000 ft), keeping %power the same, but changing the RPM (and increasing throttle to keep the same %power). Lower RPM's did give small increases to fuel economy.
 
Pierre,

You may have seen this before, but here's a good article on max endurance, max range and optimum cruising speed (Carson's speed). Googling Carson's speed yielded a few more good articles as well. Best Glide x 1.316 is the short-version formula for Carson's speed. Somewhere around 115 kts for me

I've not tested a X-C that slow, but I have seen that slowing down definitely increases range. A bunch of us flew together to KC for last year's pink flight; my fuel flows and my fill-ups were close to, sometimes lower than, the 4-banger RV's. IIRC, 150 KTAS at 12.5K', FF mid 7s (LOP to Pk), power was 17"/2100 RPM.

At some point it becomes mind over blatter (sp and pun intended).

Too bad about the jet A...woulda been a neat trip!

Cheers,
Bob
 
Pierre,
I am amazed at your explorer mindset. I could not do that flight even with avgas available.

On that note, I did find a picture of a barstool that I believe is appropriate for you. :)

10551034_610463299074962_3336197786953363758_n.jpg


Apologies to the group/moderators if it is too risqu
 
Mike S said:
Bob, you brought up an important point--------fuel used in climb and its effect on overall range.

The low----9.5 to 10 cruise figures I, Andy, and Pierre mentioned are just that--------cruise.

Thanks for keeping us honest.............
Click to expand...

...however, that higher burn on the climb is somewhat offset on the way back down. I don't know about the rest of you, but I typically use my cruse MP for the ride down hill. In other words, if I'm at 22 inches at altitude, I'll keep pulling the throttle back as I descend to maintain 22 inches. I also don't touch the red knob on the way down unless I need to advance the throttle for some reason. As a result, the FF on the ride down is quite a bit better than the cruise segment, and my speed is way up. Also, the longer the cruise leg, the more insignificant the climb segment becomes for your average fuel burn.

I'm doing Key West this winter and the Bahamas in the spring with a 540 and only 42 total gallons (Rocket), so I'm giving the subject of fuel burn a bunch of thought.
 
Range

A couple of pillows should keep the wife comfortable in the hopper of the Thrush ,and it burns Jet fuel ......problem solved
 
Max Range

Max Conrad flew a 180 Commanche from Casablanca to El Paso, a world record that still stands. He flew the same airplane with 250 hp 0 540 from Casablanca to Los Angeles.
I believe the fuel tankage was the same on both flights, but cannot find anything definitive on fuel capacity.
The airplanes were in two different weight categories because of the engine weights.

The airplane, N110LF, is on display in the museum in Liberal KS. All tanks except the seat tank are installed, the seat tank is beside the aircraft.
If the fuel capacity was 500 gallons the average fuel consumption with the 540 was less than 8.6 gallons hour. The heavy weight for the takeoff and the higher power required would suggest that the fuel consumption toward the end of the flight was under 7 gallons hour. This was a carbureted engine, the injected engine should be about 1 gallon hour less at low power settings.
 
Toobuilder;921441 I'm doing Key West this winter and the Bahamas in the spring with a 540 and only 42 total gallons (Rocket) said:
Michael, you're a good candidate for the Safeair tanks. IIRC, they add 15 gallons total....then you'd have near my range capabilities.

Best,
Click to expand...
 
g zero said:
A couple of pillows should keep the wife comfortable in the hopper of the Thrush ,and it burns Jet fuel ......problem solved
Click to expand...

Negative...it burns 47 GPH and only cruises at 140 MPH. They do, however, ferry them to Oz, South Africa and recently, six of them to China, via Honolulu, Marshall Islands, Guam, Tokyo and Shenghuan, China by filling the hoppers (800 gallons). in Air Tractors, not Thrushes. There's usually just OFF and ON fuel selection but there's an unused port on the fuel selector valve that they plumb into for long ferries. There's a header tank in the belly that both tanks dump into and from there to the engine.

Best,
 
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pierre smith said:
Michael, you're a good candidate for the Safeair tanks. IIRC, they add 15 gallons total....then you'd have near my range capabilities.

Best,
Click to expand...

Yes, more fuel for my airplane is a priority and I'm looking at developing a RV-3 style fuselage tank, but I'm keeping all my options open at the moment.

Minor correction - with more fuel I will have near the endurance as you, but I suspect that I have your range right now. I cruise at 190 (knots) on the same fuel burn as your 160 (MPH) .
 
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I cruise at 175 knots (204 mph) at 23"/2400 RPM normally and have run 217 MPH WOT during a race. The 160 MPH figure was for making Bermuda at reduced power settings.

Best,
 
pierre smith said:
I cruise at 175 knots (204 mph) at 23"/2400 RPM normally and have run 217 MPH WOT during a race. The 160 MPH figure was for making Bermuda at reduced power settings.

Best,
Click to expand...

OK. Fair enough. I saw the 160 (MPH) @ 10 from the earlier post and can beat that easily. I can still do 190+KTAS @ a shade under 11GPH at my usual 9,000 ft (typical MP is WOT 22/23, and RPM is 2200). I flight plan for 190 @11 and usually beat that. And that's with the old "tractor ignition"... I'm sure I'll pick up at least 1 GPH once I get a real ignition system installed. My "design goal" is to get 200 KTAS @10. I have a lot of cleanup to do on the airframe to get there, but that's my quest.

And I know we're talking RV-10 vs. Rocket here, but still an interesting comparison for range planning.
 
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This is the best that I have done, 13,000' between Lethbridge AB and Minot ND.
10.6 gph, TAS 218kts.
I need at least 1 knot of tail wind for every thousand feet of altitude to justify the climb, in terms of power lost.
The tapered EVO wing is significantly better then the standard rocket/RV wing at higher altitudes. I do not know how the RV10 wing compares with the other Vans airfoils in terms of higher altitude performance.

m7fhns.jpg
 
Tom, This is a C-550, right? Are you LOP in this picture? CHT's look warm enough to still be ROP (but I don't know the Big Conti's).
 
That is a curious picture, none of those engine parameters come close to my IO-550 setup, the manifold pressure is too high for 13,000ft, the fuel flow indicates very LOP and CHT's and EGT's are in the ROP range, the fuel pressure is about triple what mine is, and the RPM is also too low for that TAS when compared to most other IO-550 planes (cirrus, bonanza, etc)

Not saying any of it is false or misleading, just very very different. I have zero rocket experience- so this is educational for me.
 
This is Lycoming 540. At these low power setting I usually run very close to peak EGT, on the rich side. I used to go LOP but found that I did not like the 10 knot loss even if it was slightly more efficient. I spent quite a bit of time on this aircraft over a few years getting it to go fast for SARL racing. The benefits can be seen in how well it does on cross country flights. Although the speeds are higher I do not think that the engine settings are much different then I have seen in my other rockets.
 
Tom Martin said:
This is Lycoming 540. At these low power setting I usually run very close to peak EGT, on the rich side. I used to go LOP but found that I did not like the 10 knot loss even if it was slightly more efficient. I spent quite a bit of time on this aircraft over a few years getting it to go fast for SARL racing. The benefits can be seen in how well it does on cross country flights. Although the speeds are higher I do not think that the engine settings are much different then I have seen in my other rockets.
Click to expand...

makes more sense then, that is one clean ride you have then!
 
I file 205 knots under 8K and 210 knots above, at an average of 11 gallons. On average it usually puts me very close to my planned arrival time. I have almost 1600 hours in rockets, 850 in this one. This is my most favourite plane of all time; my wife also likes it as the wing greatlly reduces her motion sickness. (She can get sick snorkelling!!)
 
Re-Fueler

Pierre, you could convert the Air Tractor to a refueler & tank up the RV-10 (to / from) on its trip to Bermuda .. It could fly out and meet you on the way back. It does use GPS for the crop work, right!?

Just sayin'
 
Yeah, we're guided laterally to 1 foot, but cannot enter waypoints in this particular unit. The Satloc Bantam in the other Air Tractor that my pilot flies has waypoint entry capability and a moving map to depict his swaths as he sprays....I try and keep him happy. Has A/C too!

Best,
 
Prearranged 100LL

I know of several instances where AVGAS was purchased and prepositioned in Bermuda. Last one I know of was about 7 years ago. Guy was flying an Aerostar, I believe it was a 700.

If you want to do the trip it is possible without flapping your arms, but its not cheap.

http://www.aviation-fuel.com/
 
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