chris426

this has been talked about before but the issue of tank height is p***** me off for the first time. my modeltech formula 3D has some probs running. the os 91 fx is inverted and im running onboard glow. the tank is about 30mm above the carb inlet which is quite high. the motor runs like a dream out of the model. i have gone over all the fittings and fuel tube, had the tank out to look for problems and it looks fine. not much room to lower the tank unless i reduce size and cut flight time. can i use a header tank? it would have to be very small. any advice??

greyfoxx

chris426 have you considered a Perry Pump or Klien Regulator with your application? Either are viable options if you have the room.

And don't over look the fact that, "Experience is a hard teacher. She always gives the test first and the lesson some time later!"

Phillip

DRC1

My Feedback: (10)

I had both the Perry and the Klein Regulator. Both are very good, however, the Klein struggles when the needle valve is remote located (read as not on the carb body). I couldn't get it to work on the 91FX w/ a remote needle. However, never missed a beat with the Perry Pump.

LLD

airbusdrvr

I will second the problem with the Cline Pressure Regulator and OS 91FX. I could never get mine to run right. I solved the problem with a YS 61 pumped two-stroke engine. It does not care where the tank is and runs great. They are still available, some NIB, on RCU classifieds and eB**. If the 61 engine will work, it is a good choice.

DarZeelon

Chris,


All planes need the fuel tank to be mounted, so its height center-line is at the same level as the carburettor jet (the middle of the carburettor barrel), with the model in level-flight attitude.

Also, the tank must be as close to the engine as possible (smack against the rear of the firewall, with the engine smack against its front.
It must be padded from any contact with the airframe, using at least 1/4" thick Latex rubber foam (solid fuel tubes too).

The best mounting is most often the side-mount, with the exhaust pointing down.


Everyone, It is not Klien, nor Klein... It is [link=http://www.billsroom.com/pcfs/]Cline[/link].

masama1107

My Feedback: (44)

I could not agree with you more DarZeelon, but in some cases, this is just not possible. In some of the newer 3D 60 size machines with narrow fuselages, altough side mounting would be the best option, there is not enough space to side mount the engines, because the muffler would not fit at the bottom right side of the fusellage. I have the same issue with my CMP Passion 60 3D with an O.S. .91 FX.

I'm going to finally try a perry pump on it, since I've had nothing but good results with them in other ongines. Hopefully that would solve the problem. Thanks LLD for your input on the O.S. .91 FX with the Perry pump.

Chris426, I think your answer will be the Perry Pump as well....

Cyclic Hardover

My Feedback: (3)

Onboard glow will not do a thing to solve the height. I have several planes with various sized inverted glow engines and they all run excellent. No regulators or pumps installed but some with glow drivers but just for performance and not to cure a problem. Unless you lower that tank, you will continue to have problems.

Cyclic Hardover

My Feedback: (3)

You are right on this with it not being possible due to poor design. Many I know have completely gutted the fron end of those U Can Do types and rebuilt to work. Frankly, I would even make the purchase. Warbirds are notorious for this but at least it's an easy fix

DRC1

My Feedback: (10)

Yes sir, you are correct...It is Cline...I was too lazy to look it up...

With regards to the other points you made...In general I agree 100% with you about tank location. However, as pointed out by others after my post, it may be difficult to acheive this with those kits having this type of issue. On the other hand, there are those, like me, that don't want to rebuild an ARF or choose to relocate the tank for improved flight performance. For instance with the tank on the CG you don't need to retrim your plane in flight as you consume fuel. Not a problem for most sport flying, but I like hands off trim to be hands off for the whole flight.

Due to the choices I described, we have options to overcome design issues and humor those like I. For this instance the Perry Pump or the Cline Regulator. The Cline Regulator, from what I understand, operates very similar to the YS regulator in the YS61, YS63, and the larger YS motors like the 140L (non-DZ pumped engines).

My first choice is the Cline Regulator and many folks use it for the reasons I stated. But due to the concerns with a remote needle, my second choice is the Perry Regulator.

LLD

Iflyglow

My Feedback: (79)

LLD,
It is very easy to use a Cline and a remote needle, you just mount the Cline next to the Carb between the carb and the remote needle just like Jim Cline will tell you too.[)]

BlackB12

My Feedback: (9)

What is the engine doing? HAve you tried leaning out the low speed needle to help counter siphoning? I had a plane that had the tank that much higher and at first it would just slowly flood itself at low rpms. That engine used an airbleed screw but it had the same effect. I was able to get it to operate perfectly without a pump or cline reg. Note: taking that engine out and running it on it's side on my profile plane required completely different low end needle setting so for you, it may be this simple.

Mike

DRC1

My Feedback: (10)

Funny you should post that...I talked with Jim Cline yesterday on that same topic. Yes, he did say many folks are doing just that with success. I'm not sure that I tried it with the 91fx, it may verywell be the answer. The key is that it must be with in 1 inch of the carb body...not the needle valve...

LLD

rexracer

I have also seen posts here on RCU saying that a Perry pump won't help a high tank. Apparently there is no check valve or anything in the pump so fuel will flow freely downhill. The Cline worked well for me.

prgonzalez

I got the same information from Perry's support. They told me I had to relocate the tank before using the pump. Because relocating the tank was going to be a real pain, my decision was to use the cline regulator. I have not flown the plane yet, but the engine is running perfect with the regulator.

jaka

Hi!
...Any pictures of your strange tank set up?

Sport_Pilot

The best mounting is actually with the tank center somwhat below the spraybar. About 1/4" below. That is with the normal setup. That is because the muffler pressure is at the top and will be reduced by the tank head when inverted.