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Author Topic: K77 Fuel Consumption  (Read 1401 times)

Offline Chuck_Smith

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K77 Fuel Consumption
« on: January 10, 2019, 10:46:04 AM »
Guys,

I'm having some issues with fuel consumption, I need over 8 oz of fuel running on a pipe. The nose of my airplanes have 6 inches available and 2.125 width. NV centerline on a K77 is about .77 inches above the mounting rails which helps when I fabricate a fuel tank as I pick up volume on the height. I've been making sheet metal tanks which can hold about 8.5 oz if I keep everything on center. I can also drain pretty much to the last drop with them, but they are a PITA to make and don't give me a lot of extra time to walk out the lines and clean them.

Any of you have experience running a clunk tank off-center from the NVA? If I could put a 9 or 10 oz in there and have some extra room it would remove the pucker-factor on the cloverleaf. I've burped there a couple times.

I'm running 10% nitro and the K77 seems happy at lower oil content around 18%.

Thanks in advance,

Chuck

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Online Brett Buck

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Re: K77 Fuel Consumption
« Reply #1 on: January 10, 2019, 09:16:42 PM »
Quote from: Chuck_Smith on January 10, 2019, 10:46:04 AM
Guys,

I'm having some issues with fuel consumption, I need over 8 oz of fuel running on a pipe. The nose of my airplanes have 6 inches available and 2.125 width. NV centerline on a K77 is about .77 inches above the mounting rails which helps when I fabricate a fuel tank as I pick up volume on the height. I've been making sheet metal tanks which can hold about 8.5 oz if I keep everything on center. I can also drain pretty much to the last drop with them, but they are a PITA to make and don't give me a lot of extra time to walk out the lines and clean them.

Any of you have experience running a clunk tank off-center from the NVA? If I could put a 9 or 10 oz in there and have some extra room it would remove the pucker-factor on the cloverleaf. I've burped there a couple times.

I'm running 10% nitro and the K77 seems happy at lower oil content around 18%.

Thanks in advance,

Chuck

  Put a "doghouse" on the bottom of the tank. Ted and David used the metal cap from a dope thinner can, poke a couple of holes in the bottom of tank on the inboard side, solder the cap over it viola, 1/2 ounce or so, or in you case, maybe 20 seconds or so.

    Brett
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Offline Chuck_Smith

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Re: K77 Fuel Consumption
« Reply #2 on: January 11, 2019, 05:02:49 AM »
Brett, I like it. Makes good sense hydraulically too.

Chuck
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Offline Pepe Llopis

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Re: K77 Fuel Consumption
« Reply #3 on: January 11, 2019, 05:43:05 AM »
Very interesting topic, please Mr. Buck, can you post some design or Pictures? Thanks in advance.


José Enrique Llopis
Alicante - Spain
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Online Brett Buck

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Re: K77 Fuel Consumption
« Reply #4 on: January 11, 2019, 02:19:34 PM »
Quote from: Pepe Llopis on January 11, 2019, 05:43:05 AM
Very interesting topic, please Mr. Buck, can you post some design or Pictures? Thanks in advance

    I will later, but honestly, it is literally the metal cap from a can of acetone soldered to the bottom of the tank, with a few holes in the tank wall to let fuel in and out.  You can certainly make it more sophisticated, and I wasn't there when it was "invented", but if it took more than about 5 minutes for Ted to have the idea and implement it, that would be a stretch.

    Brett
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Offline RandySmith

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Re: K77 Fuel Consumption
« Reply #5 on: January 14, 2019, 06:16:13 PM »
Quote from: Chuck_Smith on January 10, 2019, 10:46:04 AM
Guys,

I'm having some issues with fuel consumption, I need over 8 oz of fuel running on a pipe. The nose of my airplanes have 6 inches available and 2.125 width. NV centerline on a K77 is about .77 inches above the mounting rails which helps when I fabricate a fuel tank as I pick up volume on the height. I've been making sheet metal tanks which can hold about 8.5 oz if I keep everything on center. I can also drain pretty much to the last drop with them, but they are a PITA to make and don't give me a lot of extra time to walk out the lines and clean them.

Any of you have experience running a clunk tank off-center from the NVA? If I could put a 9 or 10 oz in there and have some extra room it would remove the pucker-factor on the cloverleaf. I've burped there a couple times.

I'm running 10% nitro and the K77 seems happy at lower oil content around 18%.

Thanks in advance,

Chuck

Hi Chuck
Most get by with 8 ounces, so  8.5 should be  OK for you.  I would suggest that in this weather  you setup the  K77 with 5 or 7.5 percent fuel, if you start with 10 in the Winter time, you will need 20% to have the  same run in hot summer. The  K77 is a copy of the PA 75,  It makes huge power on 5%,  and  huge power on 10% in Summer

Randy
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Offline Chuck_Smith

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Re: K77 Fuel Consumption
« Reply #6 on: January 14, 2019, 06:41:30 PM »
Thanks Randy,

Up here in the frozen north they suck the fuel pretty good. I'll try dropping the nitro a bit, that should help. Great engine. Consistent as all get-out. Feels like cheating it runs so good. I'll be campaigning the K77 up in Canada this year and if I can get free I'll probably head out to Brodaks and the NATs.

I'd like to try a couple of PA 75's too.

Chuck
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