Fuel Pressure Regulators

[Robert Zambelli]

I remember seeing these a while back.
They really helped for multi-engine applications.
Are they still available?
If so, where to buy?

THANKS, Bob Z.

[Howard Rush]

Tony Huber in Renton, WA.  I emailed you his particulars.

[Randy Cuberly]

It's been over 16 years ago since I used them for Combat.  Back then I found them to be very unreliable and fragile.

Don't know anything about Mr Huber's though!

My personal opinion  is that on a multi engine project the simpler the better!

Randy Cuberly

[Dane Martin]

these are the ones i use in my helicopters, OS C spec engines and YS engines.
http://www.ironbaymodelcompany.com/index_files/Page438.htm

[Joe Yau]

these are the ones i use in my helicopters, OS C spec engines and YS engines.
http://www.ironbaymodelcompany.com/index_files/Page438.htm

Hi Dane, Would you know what this unit weights?

[Dane Martin]

Hi Dane, Would you know what this unit weights?

i believe the aluminum one is 1.1oz. they made a black one that was a little lighter.

[Brett Buck]

Tony Huber in Renton, WA.  I emailed you his particulars.

  Did you mention the very interesting observations about the various reference pressure sources, and that most of them went the wrong direction? That was the most interesting thing I learned from that experiment,

    Brett

[dirty dan]

  Did you mention the very interesting observations about the various reference pressure sources, and that most of them went the wrong direction? That was the most interesting thing I learned from that experiment,

    Brett

I kinda thought it would be interesting to let Mr. Zambelli discover this aspect to use of pressure regulators on his own. And at any rate it may have been unique to those specific engines (O.S. 15FPs for those without a script).

Dan

[Brett Buck]

I kinda thought it would be interesting to let Mr. Zambelli discover this aspect to use of pressure regulators on his own.

  I though it might avert any, er, deficiencies, in the resulting advice that might be thoughtfully passed along.

  On the other hand, it might end up being blamed on you somehow, which has a certain beauty to it

    Brett

[Jim Hoffman]

I had success using the regulators in a Classic F7F Profile Tigercat.  OS 15FP.   Fuel was stored in a bladder on the fuse.  Regulators mounted behind the motors

The regulator sealing element tended to glue itself to the seat when in storage for any time doe to the residual dried oil.  Needed to loosen them up w/ fuel before a flying session.

Over it's contest life, the airplane NEVER failed me in competition and is still hanging in the shop.  I think the custom mufflers from that airplane are currently w/ Gordan D. on his Pathfinder twin

BTW - two OS 15 FPs made more power than I expected. 

Jim Hoffman

[Dan McEntee]

   Hey Jim!
   Which Tigercat was that? I'm trying to dig the designer out of the back of my brain. A  profile model? Designer was named Adair maybe? Published in Flying Models? I had seen one once years ago, had two Fox 15's on it, vibrated like crazy. I was thinking two older steel finned OS .15s. Maybe even two of today's .061 engines?
   Type at you later,
    Dan McEntee

[dennis lipsett]

wrong thread.

[Robert Zambelli]

Hello all and thanks for all the good info regarding the regulators.

The reason for my query is that I'm considering putting a single tank on my triple engined plane. This tank would be pressurized by muffler pressure and feed all three engines through regulators.

For what it's worth, in a previous life, I was a development engineer for Homelite and I did extensive research on diaphragm type carburetors. As you may know, these carbs are flow control devices and work on a virtually identical principle as the regulators for model aircraft. The diaphragm was vented to atmospheric pressure on one side and the fuel chamber was on the other. When a higher flow rate was called for, the diaphragm on the fuel side was flexed away from the atmospheric side, opening a valve allowing more fuel to enter the fuel side. Very simple, very reliable. The float chambers on most carburetors do the same thing but are gravity-oriented.

Bob Z.

[Jim Hoffman]

Hi Dan,

You are correct.  

Bob Adair profile Tigercat,  published in Flying Models March 1968 and Classic legal.
I still have the plane, still flyable.  

It took some extreme construction techniques to get the weight low enough to even be a marginal stunter.  Fuse is a foam core w/ 1/32 balsa skins.

Powered w/ OS15 FP.  Ran high RPM w/  8-4 APCs.  Power was excellent, vibration was low.
 
Here is the only digital shot I have.  My hair is a different color these days

Jim Hoffman

[dirty dan]

 I though it might avert any, er, deficiencies, in the resulting advice that might be thoughtfully passed along.

  On the other hand, it might end up being blamed on you somehow, which has a certain beauty to it

    Brett

Yes, thanks for thinking of me. Especially as there will probably be blame enough to spread between Howard, you and me.

Or maybe not. Bob has just established himself as an expert on fuel regulators and so there won't be any issues whatsoever. Especially if he reads and further digests your comments.

For what it's worth I once had a small batch (100 pieces) of CL Combat-specific pressure regulators produced in Russia. It was merely a test of their capabilities and they did fine even though I had no real interest in marketing these specific devices; probably less than half of them were sold to various friends. Why? My experiences with pressure regulators for the Combat crowd was that an awful lot of hand-holding was involved. More than I wanted to be bothered with...

One of these Ruskie-produced regulators was at one time fitted to my Zilch-X OTS model which was powered with a Fox 35. Got it to work as well as a real good hard tank, leading Mr. McClave to refer to it and the bladder feeding it as a solution to no known problem. Alas, he was right although the fiddling was kinda fun.

Dan
 

[Robert Zambelli]

Hey, Dan - the reason for my post was to find a source for pressure regulators.
Thanks to some very helpful people, I found some good sources and information.

However, you should learn to read.
I mentioned that I did extensive research on diaphragm carburetors - I NEVER established myself an expert on fuel regulators (as you so wrongly stated), or anything else for that matter.
I am proud to say that my work did help in the development and refinement of the diaphragm carbs.

  Bob Z.

[Howard Rush]

The combat fuel regulators are kinda interesting.  People generally use crankcase pressure as a reference pressure (is that what you call it?) for the regulator.  I took crankcase pressure measurements, mainly on an OS .15 FP.  The pressure gradient is negative with RPM in the range you'd want to operate the engine.  The system works OK when the engine is screamin' lean and maybe when it's just a tad rich, but not where folks like to run stunt engines.  This is OK for combat, and Norm McFadden had a lot of success with them built into the back doors of Fox Combat Specials.  I thought constant pressure from a balloon might be a better solution, but then you'd miss out on the other function of regulators: to act as a switch to turn off the fuel when the engine isn't running.  Muffler pressure might be the way to go for stunt, but the pressure might be too puny for existing regulator designs.   

[mike londke]

Proportional Fuel Control System (Cline Valve)  available from Bruce Tharpe here- http://www.btemodels.com/  Call him at the # on top of the web page. He knows all about them and will be able to tell you exactly what you need for your application.  He"s a good guy.  Mike

[Jim Hoffman]

The pressure regulator we are discussing is intended to be installed immediately behind the engine.  The regulator takes hi (and variable) pressure fuel as in inlet, and regulates it to a rather constant pressure (outlet) to your engine. I believe my system is very much like the Paul Walker B-17 set up.

In a multi-engine model, say a twin engine Tigercat (or a 4 engine B-17) the idea is to:

1)   Have a single hi pressure single fuel tank mounted somewhere convenient, say in the fuselage.
2)   Have each tiny regulator right behind each engine to provide regulated pressure to that engine.

Due to the centrifugal force of CL flying, the fuel pressure at the regulator inlet will be VERY different at each engine.  One regulator is inboard of the fuel tank, the other is outboard.  By have the regulators behind each engine, the engines see relativity constant pressure to the spray bar and the motors now becomes immune to variations in pressure feeding the regulators.

I suspect that muffler pressure is not adequate to pressurize the fuel tank in a multi-engine system in the Tigercat configuration because the fuel head difference between inboard and outboard is way more than muffler pressure.  I used a big combat fuel bladder.  Perhaps an inline set up could use muffler pressure, but I don’t have experience doing that.

Hope this is helpful.

Jim Hoffman

[Dane Martin]

excellent info, Jim. in the helicopter world, especially two stroke YS engines, we run a tap from the engine back plate straight to a check valve, then into the tank. the pressure is extremely high, so you need a high quality tank. then everything else you discribed would be easy to do.

[Howard Rush]

I suspect that muffler pressure is not adequate to pressurize the fuel tank in a multi-engine system in the Tigercat configuration because the fuel head difference between inboard and outboard is way more than muffler pressure.  I used a big combat fuel bladder.  Perhaps an inline set up could use muffler pressure, but I don’t have experience doing that.

A combat bladder runs you about 15 psi, as I recall.  Delta pressure between adjacent B-17 engines was about 3 psi, but varied with flight condition.  A central tank would indeed need a lot of pressure, and the bladder worked a treat.  With a central tank, I'd use muffler pressure only as a reference for the regulator.  It's too little, I think, to work with Tony's regulators, which are made to use crankcase pressure. 

[dirty dan]

However, you should learn to read.
I mentioned that I did extensive research on diaphragm carburetors - I NEVER established myself an expert on fuel regulators (as you so wrongly stated), or anything else for that matter.
I am proud to say that my work did help in the development and refinement of the diaphragm carbs.

  Bob Z.

Bob,

Thank you. I stand corrected. You are not an expert on fuel regulators, despite the extensive research cited, the claimed development and improvement of diaphragm carbs.

Dan
 

[Robert Zambelli]

Thanks to all.
Per Howard Rush's suggestion, I have contacted Tony Huber regarding the regulators.
He will send me info and I'll post any results.

Bob Z.