OS 160FX setup

[Dean Pappas]

That's right, Bob.
The hopper needs a fair bit of air in it, which is exactly counter to the use of a hopper in order to de-bubble the engine run near the end of the main tank.
It is only good in the short term, but that's OK. It helped in my 1/3 Laser.
Many, many moons ago, Kavan sold a pressure carb for the popular 60s of the day.
The one for the Enya 60 (hey, Phil Kraft won the World Champs with one just the year before!) had a 
bicycle valve biult into the side of the carb, attached to a fuel nipple that was plumbed to a tank vent.
A cam attached to the  throttle arm would open the valve below 1/2 throttle and burp the tank.
Of course, if the plane was interted, it would pee out the side of the carb.
I spent hours in the backyard, annoying the neighbors and trying to get that thing to transition consistently. 
No Sir ... didn't like it.

Dean Pappas 
Sr. Design Engineer 
Kodeos Communications 
111 Corporate Blvd. 
South Plainfield, N.J. 07080 
(908) 222-7817 phone 
(908) 222-2392 fax 
d.pappas at kodeos.com 

-----Original Message-----
From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]On Behalf Of Bob Richards
Sent: Thursday, December 02, 2004 3:46 PM
To: discussion at nsrca.org
Subject: Re: OS 160FX setup


Running crankcase pressure was a very good thing for control-line engines. I had a ST .15 that would not run well without it, but ran great in every attitude with it. 
 
One problem with RC application is the fuel metering of the an RC carb does not work well with the pressure. Also, when the crankcase pressure drops as the engine idles down, there is a good chance that raw fuel can run back from the tank and into the crankcase, which will flood the engine. With muffler pressure, a little raw fuel in the muffler won't hurt anything. If you put a one-way check valve in the pressure line, then you won't get the variable pressure to the fuel tank that you really need for the carb to work well.
 
I've used one of the Cline regulators, and it seemed to work very well, but I did not get a chance to use it very long. I was testing an MVVS .61 for pattern. (Great engine!). One problem was that the carb had to be modified slightly. The carb was designed for muffler pressure, but the Cline regulator reduces the fuel pressure to atmospheric. I had thought about running a muffler pressure line to the vent (atmospheric) side of the regulator diaphragm, but never had a chance to try it out.
 
For the life of me I can't understand how the hopper tanks work. If the main tank drops 6 inches, then you still have to pull fuel from 6 inches, with or without the hopper tank. The only way I can think of it working is if there is some air in the hopper, then momentary changes in the main tank height won't be felt at the carb, but extended up/down lines would be. Still, it seems to work, and may be the route I would go. I like simple.
 
Bob Richards.


 

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