Stalker 40 tank height?

What's the proper tank height for a Stalker 40 RE in a full fuse ship?

Check with John Miller he has one in a Vector 40. Good guy.
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On my ARF Noblers, I mount the engine on 1/8 pads and recess the motor mounts in the tank area 1/8 inch. With a 4.5 oz Brodak medium wedge uniflow tank (1-3/4 inch wide; widest that will fit in the ARF Nobler) the tank height relative to engine position is about right for the Stalker .40 RE.

In one Nobler I did with an FP .40, the 1-3/4 inch wide tank only needed to be about 1/8 inch above the bottom of the engine mount lugs (with the plane sitting on it's landing gear).

I have not yet run a Stalker .40 RE with the more typical 2 inch wide tank. In that mode a 1/4 inch tank height offset may not be needed. However, I now build at least that much into the nose of all my full-fuse stunters.

It can be somewhat frustrating with the ARFs, grinding out the mounts in the tank area and getting the cowl to fit after mounting the engine on pads. But once done, shims can be switched from top to bottom of the tank as needed, to dial in an equal run up right and inverted.

I don't know why some tank height adjustability was not initially designed into the ARFs. Most plans and kits don't show any either. Some engine/tank systems seem to deliver an equal run upright and inverted, with the tank and engine sitting right on the motor mounts. But in many cases the tank needs to be higher, or the engine goes rich inverted.

By the way, if you have not yet run your Stalker .40 RE you can look forward to a very pleasant experience. It's smooth, powerful and relatively quiet. There is no muffler sticking out the inboard side and the rear exhaust keeps the model cleaner. Enjoy it! Ed Prohaska.

LAST EDITED ON May-18-06 AT 12:33 PM (CST)
 
>What's the proper tank height for a Stalker 40 RE in a full
>fuse ship?

Hi, I'll second the good reports over the Stalker 40RE. Mine, mounted in a Vector 40 has performed very well. I run mine on FAI fuel only, and haven't had to fiddle with the engine at all. I did break it in on the stand for about a half hour total . ( 3 minute runs with a cool down between runs) Even with the breakin, It took several flights before it all settled in. You can tell when that happens as the runs and needle lock in.

As for the tank hieght, I may not be of much help if you're using a metal tank. I've used a plastic RC tank on all my Stalkers. These tanks are easy to set up for uniflow, by running the pickup to the rear as usual. I replace the brass pickup weight with one of the sintered bronze filter weights.

I run the uniflow to the center of the tank, bent towards what will be the outside wall of the tank. It's better to not try to get the tubing so close to the wall, rather install a short piece of fuel tubing so it almost touches the tank wall. Make a slight bend on the outside of the tubing, right after it exits the stopper. I'll explain why later.

Take a third piece of tubing, and bend it so it ends at the upper inside corner of the tank. You can also use a short piece of tubing here as well to get it close to the corner.

To adjust the tank hieght, you check the upright and inverted lap times. If my inverted time is faster, I grip the bent uniflow tube with my curved forcepts, and raise the level of the uniflow end, inside the tank, by twisting it. This also correspondes to raising the end of the bent tube outside of the stopper.

What the important thing is, the tank doesn't move at all, rather by raising or lowering the uniflow, the engine sees that is a movement, up or down. It accomplishes the same thing with out the hassle.

This system has worked for me on all my Stalker engines.

edited for spellin' and syntacs erurs

I'm wondering why everything is spinning around?

LAST EDITED ON May-18-06 AT 09:53 PM (CST)
 
Rear exhaust version.

Full fuse installiation with homemade sheetmetal tank.

One layer of electrical tape on top of tank for anti chafe.

Tank pushed and held directly against engine crutch with foam packing (takes up bottom-side slop in tank compartment).

Tank is approximately .875" tall X 2" wide X 5.25" long yeilding around 5.125 oz capacity and is rectangular in form.

Tubing = 1/8" OD copper.

Pickup in center of tank vertically on outside wall at rear and exits front 1/8" below tank center line and 1/8" in from outside wall to accomodate fuel filter and clear heads of 4-40 mounting screws (when viewed from front canopy side up).

Uniflow vent rests directly on top of pickup at tank rear = 1/8" above tank centerline plumbed to suit your choice of muffler pressure or ram air in front. I plug end and drill hole on side of uniflow at rear (faces inside) say 5/16" to 3/8" forward of pickup to mitgate chances of sucking air.

Engine sits on 1/8" pads.

With this setup, final adjustments can be made by rotating spray bar (Tigre clone).

By the way, currently I'm doing alot of things with this engine that more conservative types might argue against.

Muffler pressure resrticted to 1/32" vent ID on tap with home made custom exhaust system machined from aluminum billet.

20% nitro

.060 worth of head gaskets (4 of them @ .015", famous Oriental brand)

22% oil .6 castor & .4 synthetic (the red stuff)

Tree-panned glowplug island (groove cut around glowplug in head to retain heat)- all big-time builders do this if needed and it is for nitro set-up.

Venturi sleeved to .290" instead of factory .300"

3 blade narrow 10.75" X 4.5" carbon prop @ 9400 to 9800 rpm depending.

Engine burns 4.5 oz in morning and 4.25 oz in hot afternoon on 625+ square inch 44 oz NOVI