A

avi8tor50

Well Known Member
Getting read for first flight. Was wondering about details for:

Fuel Flow test: How did others do it? Jack up A/C to 30 degrees? How much fuel in tanks? How long to run the fuel into a container?

Landing speed numbers for 9A (Prefer in KTS)?
Downwind-Abeam numbers-Base leg-Final-Over the fence.

Thanks all.

Peter K
9A
 
Peter,

Fuel flow: I just let it sit level and ran the pump for a few minutes, measured the output from each tank.

Speeds: landing = 49 mph = 43 kts
I try to be at 100 mph (85 kts) abeam the numbers on downwind, extend flaps fully, slows to 80 mph (68 kts) and hold that over the fence to the flare. If I really want to land shorter, I decrease my base-final speed to 75 or even 70 mph (64-59 kts)

greg
 
Chain down the tail to simulate a steep climb out and keep it there until you are confident you have gotten an accurate measurement of fuel flow by timing how long to produce a few gallons or more. I believe you want to see in the neighborhood of 150% of the required full power fuel flow. Required full power fuel flow is appx. 1 gallon/hr for every horsepower, so for 160 hp, thats 150% of 16 gph, or 24 gph. Someone chime in here if Im off base but thats my recollection

EDIT: woops - should have said "appx. 0.1 gal/hr for every horsepower instead of 1 gal/hr/hp. No change in end result though

erich
 
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I figured around .5 lb/hp per hour. At sea level, the 180 hp will consume appx. 15 gph at full power.
 
Just disconnect the fuel fitting at the carb, raise it about 16" to simulate maximum climb angle.

Put a small measured amount of fuel in each tank, pump it out (into a container), measure the time and volume and calculate the flow. Drain any unusable fuel and measure that. Repeat for other tank.

Doing it this way also flushes the fuel system.

You should get about 25 gph using the Facett electric pump. Less than 20 and you should start looking for problems.

Vern
 
Speeds: landing = 49 mph = 43 kts
I try to be at 100 mph (85 kts) abeam the numbers on downwind, extend flaps fully, slows to 80 mph (68 kts) and hold that over the fence to the flare. If I really want to land shorter, I decrease my base-final speed to 75 or even 70 mph (64-59 kts)
Click to expand...

I'm not sure you want to be dumping full flaps at 100mph since Van has set Vfe at 90mph. I read somewhere you could drop partial flaps at 100 but not full flaps. I've made it a personal rule to not drop any flaps until 90mph.

My numbers for an RV-9A / O-320 / Sensenich FP and solo flight are 90mph downwind, abeam numbers reduce power, drop 10 degrees flaps, start your decent and maintain 90mph. On base drop another 10 degrees flaps and slow to 80mph continuing decent. On final drop the remaining flaps (32 degrees total) and slow to approximately 70 - 75mph over the numbers. I typically cut power over the numbers and just let the airplane bleed off speed keeping the mains off the ground. I usually touch down at about 55 to 60mph and I then keep the nose wheel off the ground for as long as I can, actually you want to gently bring the nose wheel down before you get too slow otherwise the nose will come down a bit hard. These numbers are pretty consistent for me and seem to work quite well. Of course speeds will vary according to wind condiditons.
 
Fuel FLow

My DAR wanted a fuel test done the following way. I have a tail dragger, so I blocked up the mains with the tail on the ground, till I had 15 degrees. This required about 10 inches under the mains. I don't know how it would work out on an A but you might be able to just tie the tail down as others have said. Once I had the 15 degrees I put a little over 2 gallons in each tank. It was only required to do one tank but I did both. Then use your backup pump and pump 2 gallons into a measured container. Time the time it takes to do this and figure out your gallons per hour. Use your book that came with you engine and figure the required fuel flow at full throttle. Multiply the required fuel flow times 1.5 and that's what you need to get from the backup pump. My O-360 requires 14.8 gallons per hour at full power according to Lycoming. Times 1.5 was 22.2 GPH. My facet pump rated at 30 GPH, put out 32 GPH. If you would like I can email you the report I submitted to the DAR. You could use this as a template for yours. The other thing I did while I was at it was to see how low the fuel could be pumped in each tank. I got the left tank down to I think 6 ounces, the right was about a half a quart. I also poured measured amounts into the tanks to mark my fuel gauges at 1/4, 1/2 and 3/4 full. You'll be surprised how off your gauges can be.
 
Follow up - check the latest "Savy Aviator" column from Mike Busch on the Avweb site. Here is his bottom line:

For a normally aspirated fuel injected engine designed to run on 100-octane fuel (8.5-to-1 compression ratio), takeoff power fuel flow in GPH should be roughly 9% of the engine's maximum rated horsepower. (For example, an IO-520 rated at 285 horsepower should flow about 25 to 26 GPH.)


For a factory-turbocharged engine (7.5-to-1 compression ratio), takeoff power fuel flow in GPH should be roughly 10.5% of the engine's maximum rated horsepower. (For example, a TSIO-520 rated 310 horsepower should flow about 32 to 33 GPH.)
 
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