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Stalker Engines---General Information


Stalker .51 Side Exhaust Stunt Engines

Tom Dixon announces that Stalker Engines has agreed to produce a side exhaust version of their .51 RE. The .51 SE will be exclusive to the
U.S. market; and will be available at the first of 2018.

Weight of the engine will be approximately 9.22 ounces. A factory quiet tube-type muffler comes with the engine. Tongue-type mufflers will be available from U.S. suppliers.

All Stalker engines are ABC, baffle piston designs, specifically built for control line aerobatics. They run very well on low, or zero, nitro fuels in a classic "4-2-4" type run.

The Stalker .51SE is a great choice for large profile models, as well as Classic, Nostalgia, and Old-Time models, whose nose design is not compatible with a rear exhaust engine.

Price for the .51 side exhaust engine will be in the $315.00 price range, but is not finalized as of this date. For more information and/or to reserve a Stalker 51SE, contact Tom Dixon at (770) 592-3279, or write to: 315 Santa Anita Avenue, Woodstock, GA 30189.

Other Stalker engines from .40 to . 76 are also available

Stalker Stunt Engines

All Stalker engines are ABC, baffle piston, ball bearing designs built specifically for control line precision aerobatics. The rear exhaust (RE) engines allow the furnished muffler to be hidden in the fuselage. Side exhaust (SE) engines have traditional bolt-on lightweight tube-type mufflers. Stalker engines sold by me are equipped with Sig R/C glow plugs and SAE size prop nut. All Stalker engines have ¼ X 28 threads on crankshaft. Available engines are listed below. I may not have all in stock at a given point, as I must "bundle" orders from Ukraine· for efficient shipping and payment purposes, but delivery is very prompt.

Stalker 40 SE $281.00
Stalker 40 RE $281.00
Stalker 46 SE $281.00
Stalker 51 RE $310.00
Stalker 51 SE $310.00
Stalker 61 RE LT $332.00
Stalker 61 RE longstroke $332.00
Stalker 66 RE $378.00
Stalker 76 RE $458.00
Stalker 76 SE $458.00
Stalker 81 RE $458.00 -- Special order only
Discovery Retro 68 (Yatsenko) $458.00 (No nitro-side mount)

Prices are subject to change due to currency fluctuations and varying shipping costs to get the engines to USA. Exact price verified at time of your order.

 


Modifications Of Your Engine

I am still providing re-work services on OS-FP and LA engines supplies by customers. (Some other engines can also be re-worked.)  My modifications allow the engine to run in a traditional 4-2-4 manner at lower RPM, allowing use of 5" or 6" pitch propellers.  Most people find this type of run to be more pleasant, more "traditional", and there is no need for special carbon fiber low-pitch propellers.  Most wood propellers on the market will work just fine.

     The FP-LA re-work consists of:

          Re-Time sleeve
          Correct-size Venturi
          Double Star needle valve unit
          SIG R/C glow plug
          Double Star tongue muffler
          Test run
          Return shipping in the U.S. and Canada

Total Price $85.00 per engine

Send the engine, Priority Mail, to:

Tom Dixon
Controline Sales L.L.C.
315 Santa Anita Ave
Woodstock, Ga. 30189
U.S.A.

Payment can be made by cash, check or money order.

The re-worked FPs and LAs work especially well on profile models.

All OS-FP or LA engines, from .25 to .46, can be re-worked. (The LA 60 is too heavy to be useful.)

Turn-around time is usually within five days from the time I receive the engine.

 

 

ENGINE TUNING STALKER, AND OTHERS - June 2017

 

Stalker engines, Double Stars and some others were designed for zero, or very low nitro-methane content in the fuel. Most USA fuels have at least 5% nitro, and more commonly 10% nitro.

In control line stunt use, running nitro fuel at stock cylinder head spacing in these engines can result in sensitive needle valve settings,
"run-away", or too hard a 2 cycle break in maneuvers. One solution is to lower the compression ratio via machining material off the squish-band of the cylinder head, usually ten to thirty thousandths of an inch. Easier, and much more adjustable, is to simply raise the head via head shims/gaskets. For most "no nitro" engines, adding 0.030" in head shims is pretty close. In cold, dense air, more spacing (shims) will likely be needed. The opposite is true for 100 degree weather in Tucson or Phoenix.

Many of the early Brodak .40's were over compressed, and respond well to shimming the head up. This gives a much broader needle, and no real loss in usable power, and starting without "biting" your fingers! Simply use extra head gaskets from Brodak to do this. Add shims until the 2 cycle break power falls off, and then remove 1 or 2 for optimum setting.
Any engine will make more power with more Nitro in the fuel. Often, for stunt engines, lowering the compression makes it very docile and friendly. Adding nitro brings up the power without changing the run characteristics. Extra nitro doesn't turn it into a racing engine - it just makes it a "torqueier" stunt engine. I often vary nitro level as the day gets hotter by adding, say, 1 ounce of 25% nitro fuel to 4 ounces of 5°/o, to yield 5 ounces of 9%. Two ounces of 25% nitro fuel and 3 ounces of 5% yield 5 ounces of 13%. I keep two quart bottles of fuel in my flight box, one 25% nitro and the other whatever base fuel that I'm running for the particular engine of the moment, either 5% or 10% nitro.
By filling the tank with a 5 ounce graduated syringe, it is easy to measure the amounts needed.

As a rule, engines get easier to set the lower the prop load. This is because a larger diameter prop requires a leaner needle to make more power to turn it. A leaner needle means there is less fuel now flowing hrough the engine, and less cooling as a result. I find that running the smallest practical diameter prop that will adequately pull the plane is
always best. This usually means a 10 to 10 1/2 inch diameter for .35/.40's, 11 inch diameter for .46 to .50's, and 12 inch or so for .60's. run a 13 x 5 wood on my Stalker . 76 and it is very happy there.

Smaller props also cause less gyroscopic precession (side-way wiggles) as the plane maneuvers. Lighter (wood) is better than heavier plastic too. If the engine is "happy" but the plane is too fast, reduce the prop pitch at the same diameter and needle setting. If the engine is happy and the power seems low, go up in pitch one inch. I've seen lots of guys who have great running engines on models falling out of the air - turns out their buddy told them to run a 4 or 5 inch pitch prop when they really needed a 6! This is especially true on heavy, or draggy airplanes and hot weather. If your engine is running well, and you are running a 6 inch pitch prop, but the plane won't perform well, then you need a lot more nitro, or a new/or bigger engine!

While electric power is becoming more popular in control line stunt, electric systems cannot completely compensate for temperature (air density) changes. An electric motor does not lose power as the temperature rises, since it doesn't use air for it's power. However, it is hard to add power to an electric, on the field, to compensate for lower prop and wing efficiency as the temperature (density altitude) rises. On a glow engine, just add more nitro! Extra power (not speed) will overcome a lot of efficiency loss of the wing and propeller!
Glow plugs are a crucially important part of an internal combustion stunt power system.

"Hot" plugs are required! My favorite glow plug has, for years, been the Sig RIC (#SIGGP003). The newest Sig RIC plugs are produced by
another manufacturer, but appear to have the same running character ----- Thank goodness! Many people have liked the Thunderbolt line of plugs, but as of this date, they are no longer available. Some of the Merlin line of plugs may be hot enough to work---I have not tested them. My refrain for a long time, has been, "Put a fresh Sig Plug and good fuel in it, then let's see what else it may need."

This has been an attempt to hit the "high points" of stunt engine
tuning. If you have more questions or problems, feel free to call me at 770-592-3279.

STALKER ENGINE UPDATE

Below are some points I have gained from flying (and selling) Stalker engines from .40 to .76 for about 2 1/2 years now. You may benefit from these:


Tank Height/NVA Position -If the engine, and standard 1 inch thick tank, both sit flat on the motor mount beams, the engine will run richer inverted. (Standard cylinder
towards landing gear installation). A quick, easy 'fix' is to remove the needle valve assembly and drill a second hole for the fuel outlet directly across from the original hole. Use a #55 or #56 drill bit, drill through the original hole, and out the other side. Be sure to remove all metal chips! Re-install the spray bar with the holes pointed fore and aft in the venturi. Doing this raises the place where the fuel meets the atmosphere by approximately 75 thousandths of an inch ... it's the same as shimming the engine off the mounts that much.

Of course, if you are building a new plane, put 3/32 inch (.093 ") aluminum pads between the engine and the wooden beams. If using a plastic tank, the center of the tank still needs to be about .075" to .080" below fuel exit hole(s) in the spray bar. On profile models, the center of the tank needs to be about 5/16 of an inch above the centerline of the engine (side exhaust, outboard mounted cylinder). Side mounted, side exhaust Stalkers will often give a "Fox burp" on outside turns (wingovers, outside squares) but will always keep running.

Nitro and Head Shim Spacing -If running nitro fuel, Stalker engines will require somewhere between 20 and 50 thousandths additional cylinder head spacing. Start with .030", and add a shim if the 2 cycle break is too harsh or too long. If the power is soft above 45 degrees, take a shim out. In hot weather or high altitude, more nitro, or less head spacing may be needed. The opposite is true at sea level, or cold weather. Stalker provides about 40 thousandths worth of .008" shims with each engine. 0.010" shims are also available from me or Jim Lee. In my engines, I have usually run .030" of shims and use 5% nitro Sig Champion fuel.

However, with the recent problems with Sig fuel availability, I am going to re-tune everything for zero nitro fuel. Preliminary 'backyard' test running showed no difference in starting on 0% nitro fuel. I have mixed my own 0% nitro, 18% synthetic oil fuel with methanol purchased at a local go-kart/motorcycle racing shop. A 5 gallon container of VP brand straight methanol was about $35.00 including the can. The oil is Klotz from Sig ... next time I will probably get the oil from the place that sells the methanol.
They may have the nitro too, but I want to fly without dependence on nitro.
Fortunately, Stalker and Discovery Retro engines were designed from the beginning to use no nitro fuel. No nitro fuel is easier on finish materials too.

Props -I generally prefer wood props for cost and availability reasons. However, Steve Wilk (Eliminator Props, (763) 257-3588, cell, Swilk117@yahoo.com) is a USA manufactured source for carbon fiber props. Many are copies of Rev-Up stunt size two blade props. He also has 3 blade props aimed more at the tuned pipe engines, but I am sure they could be pitched up if needed. Steve's website is Eliminatorprops.com.

Retro-fitting -Stalker engines are a bit longer, mounting holes to prop driver, than similar engines. However, with a little work, they can be installed in the place of existing engines. The mounts in the plane need to be re-drilled, then fitted with threaded inserts (available from Sig, DuBro, Brodak's, etc.). You only need to drill far enough, approximately 3/8 of an inch, so the inserts will be flush with the top of the motor mounts. A piece of masking tape wrapped around the drill bit helps as a guide to drill "just to the tape". Fill the old mounting holes with dowels and epoxy unless you want to switch engines back and forth.

The threaded inserts actually have an advantage, as the engine cannot compress the wood beams; it can only tighten down as far as the inserts. Naturally, you will need to modify the NVA and exhaust outlets, etc. too.

Tom Dixon 2018

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