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-   -   mile for mile (https://vansairforce.net/community/showthread.php?t=9578)

Joey 07-28-2006 04:20 AM

Quote:

Originally Posted by gorbak
How does the gph of a 118hp compare to a 160hp lycoming?

Extrapolating Van's numbers for the 118 hp engine (and checking the Lycoming Engine Manual) we get an estimation that follows:

Full power 173 mph 4.53 flight hrs 7.5 gal/hr
(assuming 34 gal. usable..start/taxi/takeoff...)
75% power 166 mph 5.27 flight hrs 6.45 gal/hr
55% power 150 mph 6.90 flight hrs 4.92 gal/hr

Van's RV-9A, N129RV, burned 6.1gph at 179.6mph (29.4mpg) when tested by the Cafe Foundation. Power was provided by a 160 horse O-320. That engine can be operated on premium automotive gasoline, too.

prkaye 07-28-2006 07:24 AM

>> That engine can be operated on premium automotive gasoline, too.

>> The poster listed a 150 HP RV-9, which could burn mogas

Curious, where does this information come from? From what I've seen on Lycoming's website, they say nothing but AVGAS for all their engines. How does one know whether you can really safely run MOGAS in these engines?

>> Consider this. Go ahead and put the 160 HP Lyc in and when prudent throttle back to a fuel burn of the 118 HP engine

Be interesting to see how the consumption rates compare for the two engines running at the same speed, say 150mph. The 160HP would be going that speed at a lower power setting, but it's a bigger engine overall. I wonder how close the GPH would be between the two engines running at the same speed (150MPH).

Bruce Reynolds 07-28-2006 08:27 AM

Weather factor
 
I have had to park my plane (twice ) in bad weather and take the Greyhound home. No fun at all. Then I had to arrange to get back and retreive the plane. The saying goes, "When you have time to spare, go by air". I never leave home without bus fare. Having said that, I have made seven trips from Salem Oregon to Southern California in my RV and it's far better to fly than drive.

Joey 07-28-2006 03:52 PM

Quote:

Originally Posted by prkaye
>> That engine can be operated on premium automotive gasoline, too.

>> The poster listed a 150 HP RV-9, which could burn mogas

Curious, where does this information come from? From what I've seen on Lycoming's website, they say nothing but AVGAS for all their engines. How does one know whether you can really safely run MOGAS in these engines?

Peterson Aviation has done extensive testing on auto fuel use in aircraft engines. They sell auto fuel STCs. You can see a list of engines on their website, www.autofuelstc.com
Quote:

>> Consider this. Go ahead and put the 160 HP Lyc in and when prudent throttle back to a fuel burn of the 118 HP engine

Be interesting to see how the consumption rates compare for the two engines running at the same speed, say 150mph. The 160HP would be going that speed at a lower power setting, but it's a bigger engine overall. I wonder how close the GPH would be between the two engines running at the same speed (150MPH).
So close as to be negligible. Regardless of the engine, an aircraft takes X amount of power to go Y speed. Assuming engines of similar efficiency (and most typical aircraft engines are) the fuel burn will be very close to the same.

If you come across some reliable performance numbers for an O-235 equipped RV-9, compare them to the Cafe Foundation report on the O-320 powered N129RV. The O-320 -9 will at least match the O-235 for efficiency in most situations.

Kevin Horton 07-28-2006 07:01 PM

Quote:

Originally Posted by prkaye
Be interesting to see how the consumption rates compare for the two engines running at the same speed, say 150mph. The 160HP would be going that speed at a lower power setting, but it's a bigger engine overall. I wonder how close the GPH would be between the two engines running at the same speed (150MPH).

The smaller engine will probably have a very slightly lower fuel burn, but the difference might be too small to measure. The small engine has three things going for it in this scenario:

1. smaller displacement means less frictional losses to turn it at a given rpm,

2. the throttle will be further open than the one on the larger engine, leading to lower pumping losses, and

3. the aircraft with the smaller engine should be a bit lighter than the one with the larger engine. The lighter weight should mean a bit less induced drag.

Robert M 07-28-2006 08:24 PM

(disclaimer) I'm only repeating what I have heard about the 118 hp gph.

I have been told that the 118 hp engine uses about 5 - 6 gph in econ. cruise.

According to Van's (and I think their numbers are pretty accurate) that would have you zooming along at 150 mph.

The biggest draw back for flying to visit relatives and such is ground transportation. Yeah, they can pick you up and drop you off but I would rather rent a car. Of course the "Wanna fly in my plane?" usually gets instant cooperation from anyone.

If your trying to save money by flying instead of driving - you might actually come out better going commercial.

HOWEVER! Getting in YOUR plane and flying yourself to whatever destination you desire brings into light the COOL factor. The COOL factor outweighs any and all cost or time considerations.

jcoloccia 07-28-2006 08:42 PM

Quote:

Originally Posted by Robert M
HOWEVER! Getting in YOUR plane and flying yourself to whatever destination you desire brings into light the COOL factor. The COOL factor outweighs any and all cost or time considerations.

That pretty much says it all.

N941WR 07-28-2006 08:58 PM

Quote:

Originally Posted by Robert M
HOWEVER! Getting in YOUR plane and flying yourself to whatever destination you desire brings into light the COOL factor. The COOL factor outweighs any and all cost or time considerations.

Flying in the big birds is like taking a Greyhound buss After 9/11 and all the so called security measures, I now avoid flying commercial every chance I get. I can't wait until my -9 is finished!

Robert, where in SC are you located?

jsherblon 07-28-2006 09:32 PM

I've never lost my luggage when I'm the pilot.

arffguy 07-28-2006 10:14 PM

That definitely says it all
 
And:

Quote:

Originally Posted by jsherblon
I've never lost my luggage when I'm the pilot.

And was it Doug or Rosie that said that he could take his handgun and nail clippers too? Plus the plane leaves when and where you usually want it to.

Back to the small engine debate:

Wouldn't an RV-9 with an O-235 at 118 HP still use close to the same amount of gas as a 110 HP Cessna 152 at any given RPM?


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