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Author Topic: .15 carrier questions  (Read 56484 times)

Jim Roselle

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Re: .15 carrier questions
« Reply #50 on: September 10, 2015, 01:26:51 PM »
Eric,

Thank you. I was planning on Tucson this month but don't think I will make it since I am going in for hernia surgery tomorrow. I will definitely be at carrier plus in October.

Jim

 
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Offline Burt Brokaw

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Re: .15 carrier questions
« Reply #51 on: September 12, 2015, 01:14:05 PM »
Hi Jim

I just read Eric's comments on my tank tuning.  The solution he is describing that I used was for a very different problem than the one that you have.  The procedure that he described was to solve the problem of going rich AFTER takeoff and staying that way for the entire high speed run.  Which is a different problem than the one that you are describing.  Wish that you were able to come down for the Marschinke so that I could see for myself firsthand what you are experiencing.  Going rich during the takeoff and then leaning out after a lap or so is something that I don't remember ever running into.  Are you sure it is not going lean on takeoff and then richening up after a lap or so?  That would be a more understandable problem.

I do not normally log onto forums (or any other social media for that matter) but did so this time at Eric's request.  I would welcome any chance to help in any way that I can but direct contact is preferred.

Burt
lecreit@msn.com
520-743-3003  hm
520-360-6552  cell
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Offline john vlna

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Re: .15 carrier questions
« Reply #52 on: September 14, 2015, 05:33:20 PM »
The problem does sound a bit odd, but I do think it is a vent problem. Try moving the vent, I suggest moving it to the front of the tank. The distance outboard may also need to be adjusted where it ends in the tank. A vent in a uniflow at the back of the tank will normally be rich on the ground and then lean out. Several laps is odd, but ??? could be. Each tank can have it's own peculiar characteristics.
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Jim Roselle

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Re: .15 carrier questions
« Reply #53 on: October 24, 2015, 03:06:06 PM »
Well, I messed with the tank by moving it outboard and helped sporadicly. I decided to take it to Phoenix Carrier Plus today even though there's no way it could do an official flight. Jim Hoffman suggested the venturi might be too large. I jammed a broken off piece of ballpoint pen in the venturi (see photo) and gave it a try. I still need to fine tune it but it flew well enough to make two officials. I plan on replacing the pen piece with some aluminum tubing in the future but the pen worked well enough to have a lot of fun today!

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Offline Paul Smith

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Re: .15 carrier questions
« Reply #54 on: October 26, 2015, 09:16:58 AM »
I think you have hit upon the fix.  RC engines are designed to have muffler pressure and often the venturi is too bog to work without it.  This is especially true with a light plane that accelerates quickly.  One fix is to get the fuel pickup inboard, at least even with the venturi.   The other is to choke down the venturi.

Finally, some (maybe all) contests allow you to just use the muffler with muffler pressure.  The weight and back pressure of the muffler is a tradeoff for getting the engine to run.

Or you could just dump 75 amps through a 40,000 RPM dentist's drill and forget about it.
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Paul Smith

Offline Wayne J. Buran

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Re: .15 carrier questions
« Reply #55 on: October 26, 2015, 01:01:30 PM »
Jim, I use the ASP 15 R/CV in my .15 Guardian with  Brodak BH-547 wide wedge uniflow tank which is stock with no issue. See the illustration for tubing positions in there catalog. The vent tube is about .250 to .375 outside of the carb fuel nipple. The fuel pick up  looks to be about .250 above the glow plug center. Engine runs fine on low and high speed.
I will say that I just had a similar problem like yours on my Fairey Firefly Profile. That is powered by an Irvne .36 ABC with an OS 4BK carb. The tank is a 6 oz oval and standard vent. Until I moved my vents right up front and at least .375 outside the fuel nipple I had the same issues, take off screaming, get fat after lift off and started lean out slightly as fuel was consumed. Now it is fine so the vents do impact fuel suction. I'll try to post a picture.
Wayne
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Wayne Buran
Medina, Ohio
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USAF Veteran 35 TAC GP/ 6236 CSG, DonMuang RTAFB, Bangkok, Thailand 65-66 North Coast Controliners   "A fine is a tax for doing wrong. A tax is a fine for doing well!

Offline Wayne J. Buran

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Re: .15 carrier questions
« Reply #56 on: October 26, 2015, 01:15:45 PM »
Vent position. Two pictures. Close lower vent and notice position of top vent. Also side view. I used this tank because of the wing position. Hope this helps.
Wayne
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Wayne Buran
Medina, Ohio
AMA 14986 CD
USAF Veteran 35 TAC GP/ 6236 CSG, DonMuang RTAFB, Bangkok, Thailand 65-66 North Coast Controliners   "A fine is a tax for doing wrong. A tax is a fine for doing well!

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