Kitfox vs RANS, The Building Experience

[Danzer1]

Hey Lowell, thanks for the added info. I certainly understand how the Rans could consume that amount of fuel (or any aircraft for that matter). Piloting technique, dirty aircraft - could have been a dacron covered s6 with the big wing, pitched for climb, needed a tune, combination of all, etc, etc...

What I don't get yet is how a Model IV can achieve 2.4 gph averaged over a 3 hour flight - which also had to include taxi, takeoff, climb etc. Clean it up all you want, but that's a mighty impressive fuel flow figure for any bird. I'm sure there are a bunch of us that would like to know what engine, PSRU, prop combination can achive that 2.4 gph avg. burn throughout an entire flight envelop. Not yet clear.

Thanks, Greg

[Norm]

What I don't get yet is how a Model IV can achieve 2.4 gph averaged over a 3 hour flight -

Thanks, Greg

My Model Iv is giving me incredible fuel economy. I don't know if it's quite that good but I did a 2.7hr flight as per hobbs and replaced the fuel I burnt with a 28litre jug of premium. That is about 7.4 US gallons So about 2.7 gal per/hr. Not quite as good as 2.4 but I find it believable depending on how level the plane was when it was filled at home and how level it was when filled at airport pumps. It's possible it was not fully filled.
One thing I know is it sure is nice to go fly for a few hours for less that $30. Just a little more that $10/hr.
Especially after running a 582 for the last ten years. Oh and no oil to add.

[Danzer1]

My Model Iv is giving me incredible fuel economy.

Hi Norm, That's great info! I know you have a 912, but which version and prop? Also, do you recall your avg. rpm and airspeed?

Thanks, Greg

[efwd]

Personally, I like that Kirk guy in the story.

[WWhunter]

Ditto, now that I have the full picture I can definitely understand the difference in fuel burns. Unfortunately (or fortunately, depending how you look at it) I am like the guy that flies at 20' AGL. I like to zig-zag all over and see thing up close. Yes, I would be the guy with the higher fuel burn!

[LSaupe]

One other factor might also be company and forum support. When I built my Kitfox, the company and forum support was really great (and I was building an old Model III). It would be rare that I would go more than a day without resolution on a question/problem I might be having. Any parts need from Kitfox were also quickly fabricated (if needed) and shipped.

My only interaction with Rans was with their bicycle division. What I experienced for customer support was poor at best (and these are some higher end bikes/recumbents). Hopefully the aircraft division is much better (they have also sold off the bicycle interests). I have no experience with their aircraft side of the house.

[Norm]

Hi Norm, That's great info! I know you have a 912, but which version and prop? Also, do you recall your avg. rpm and airspeed?

Thanks, Greg

It is a 912Ul with an IFO ultralight three blade prop. I have not put the inflight adjustable motor yet. I have it running about 5200 on take off and can hit 5650 in level flight
The day I got the 2.7 burn I was running 5200 to 5350. Airspeed at that RPM is about 90-95mph. I hope to get better once I have my inflight adjustable.
Altitude was about 4500asl and temps in the range of 45 to 50F
And yes I am still loving this new to me bird.

[Flybyjim]

My Rans S-7 with 100hp rotax Keiv ground adjustable 3 blade prop at 5200 burns 4gal per hour at 3000ft.

[Flybyjim]

Should have added at 5200 I cruise at 112mph

[av8rps]

I can believe Lowells' 2.4 gph number. Flying an aerodynamically clean 912ul Kitfox 4 with much slower, draggier aircraft could allow the Kitfox to fly at significantly reduced power settings. My 912ul Kitfox 4 with two 14 ft heavy and draggy amphib floats only burns a hair over 3 gph at approx 100 mph. So if I got rid of those floats and slowed down just a bit it wouldn't be too hard to get the fuel burn down by another half a gallon per hour.

These planes are really efficient. I once tested my plane just to see how low of a power setting it would fly at while still maintaining altitude...at approx 3500 rpm and 63 mph my fuel burn was less than 1.5 gph. And I could have flown forever at that speed as it flew just great even with that super low power setting.

Sorry for getting off the original building question this thread was started with.

Paul