Tank facing location for pusherprop
 

The Sr-71 is getting close to compleation,the book shows the tank with the klunk up towards the front of the plane.This does not sound right to me.I would asume the tank be installed in the same direction as a standard foward mounting motor.This plane is a pusher.Am I correct?The way the weather is around here the maiden may be on skis.


Thanks Frank

RE: Tank facing location for pusherprop
 

That does sound strange. On my pusher the clunk is toward the back of the plane. I first installed it facing the front and had nothing but deadsticks... that was until we turned the tank around... flies great now.

RE: Tank facing location for pusherprop
 

The clunk should be towards the rear of the plane. The main drawback of pusher / tank set ups is that when you go into a climb, the tank is above the engine. This tends to make a lot of engines want to go rich, when you actually want them to lean out a little for more climbing power.

RE: Tank facing location for pusherprop
 

Frank,

As noted, the clunk should face aft. I guess it is possible for it to work facing forward, but only for part of the fuel load.

Worth noting, if you use a bubble tank, it doesnt matter which way it is installed

RE: Tank facing location for pusherprop
 

Hi!
Use a Tettra "Bubble" tank and you have no clunk to worry about...

RE: Tank facing location for pusherprop
 

Frank,

In a Bobcat 50 (NitroPlanes) I put the tank in with the neck pointed aft ( fitting thru the fomers)and I had the fuel line to the front of the tank and a 180 dergree bend in the brass tube ( so it doubles back) and more fuel line with the klunk in the aft end of the tank.

I worked ok but the fuel line and vent tube prevented the Klunk from have full movement in the tank. AND after half a flight inverted flying was out of the question because the klunk would hang up on all that plumbing! I bought a Bubbles tank from JETT Engineering. Tank upgrade and spring air retracts are scheduled for winter non-flying/maintenance season.

bob

RE: Tank facing location for pusherprop
 

It sounds like the bubble tank is the way to go.But it sounds like a pain to fill.Do all bubble tanks fill the same way?And do you you need a special extra filler tank for them?

RE: Tank facing location for pusherprop
 

Can someone tell me about filling the bubble tanks.Do you need a special filler?


Thanks Frank

RE: Tank facing location for pusherprop
 

One needs a syringe to fill Bubble tanks. Preferebly a large one.

The procedure is this. with the syringe suck all of the air out of the tank.

Clip the feed line to prevent air returning to the tank.

Fill the syringe with fuel and connect to the feed line. Remove the clip.

Give one last pull on the syringe to remove any last bubbles.

Fill the tank and clip the feed line. connect to the engine.

The procedure may change depending on the syringe size. If a syringe can be obtained that is twice or more the capacity of the tank it is lot easier. Then the syringe can be half filled, connect to the tank to suck there air out and then immediately fill the tank.

Ed S

RE: Tank facing location for pusherprop
 

Thanks Ed that is what I needed to know.

RE: Tank facing location for pusherprop
 

The "Jett Super Tanker" is the ticket... works like a charm!

RE: Tank facing location for pusherprop
 

You can also fill these with your electric pump from your flight box. Just let the pump suck out all of the air first, then fill. you have to be careful not to overfill the tank, as it will get slightly pressurized if you let it fill completely. If that happens, let it bleed off a bit or else you'll get too much fuel at the carb when you go and start the engine. I do this all of the time on an 18 ounce Tettra tank, and it works very well. If you have a small tank, use the syringe method, as it's easier.

RE: Tank facing location for pusherprop
 

Using a bubbleless tank, it makes no difference which way the tank faces.

As you can see in the picture the tank is in backwards. This was for installation convenience.

Ed S

RE: Tank facing location for pusherprop
 

I have an Enforcer with a standard tank facing aft and it does seem to bog a little during climbs. A bubbless tank seems the way to go for me. Can anyone provide a link to purchase the bubbless tanks?

RE: Tank facing location for pusherprop
 

Hi!
You fill a bubble less tank the same way an ordinary R/C tank...using an electric fuelpump or mechanical fuel pump. You certainly dont have to suck out any air before you fill it up!
I have done this for 15 years in F3D and Sport 40 without any problems.
I admit that the best way is to fill it up using a syringe sucking out the air first...but in practise you don't have to bother sucking any air out at all ...just fill it as with an ordinary tank!!

RE: Tank facing location for pusherprop
 

www.jettengineering.com Jett offers a few different size Bubble-Jett tanks up to 12 oz

www.centralhobbies.com Central carries a full line of the Tetra bubble tanks, all the way up to 24 oz I believe.

Keep in mind, a bubble tank utilizes 100% of its fuel capacity - no unusable fuel or risk of uncovering the clunk. So sometimes you can get away with a slightly smaller tank.

RE: Tank facing location for pusherprop
 

Thanks for the links BOB27s. I'll order from central hobbies. I had good past experience with them.