Miniature Aircraft's

FURY EXTREME

November 27th, 2002:

 

OS 60B 3 Needle Carb, Bellwood Dual Glow Head, BackPlate HeatSink and the Perry Pump:

Well, I've been tinkering again, I was having problems with my stock OS91 flooding on me causing hydrolocking problems. Out of desparation to resolve that problem I replaced the stock two needle 91 carb with the 60B carb. I was hoping it would resolve the hydrolocking problem. I really didn't have any problems with the performance of the stock carb, once running mine ran pretty darn good. In the picture below you can see the 3-Needle 60B carb installed and you can clearly see the additional plumbing the Perry Pump requires. If you look closer you will notice a triple fin on the bottom of the engine. That is a modified Bellwood OS91 Backplate Heatsink. I had to machine about half of the fins off to make it fin between the lower frame brace and the engine. I figured even a reduced amount of fins would be better than none.

Also in the photo you can see the big green Bellwood Dual GLow Head. I have used this type of head before. I had a Webra 61 P5 that would not idle very well to matter what I did, also it wasn't a very powerful motor. I took a chance and ordered the dual glow head for the Webra and it really helped that motor. I got the Bellwood head and Backplate heatsink from a fellow modeler who didn't want it and I got it cheap so I couldn't resist trying it. I had heard alot of people have used the OS Blue HyperHead for more power but it really didn't help smooth out the motor nor did it make it idle any better. I only have about a gallon though this configuration and that is breaking in a new piston and ring so it's too early to tell how goood it will ultimately perform but early tests look very promising.

 

Above is a shot of the Cutris Muscle Pipe 2. Fat little sucker isn't it? It seems to be a very good muffler. It is quiet and seems to have as much if not more power than the Hatori SB-15. I do worry about the MP2 being a one piece unit, even though it really is a two piece they are hard bolted together.

Here's a shot from behind, you can see where I had to cut out about an inch and a half from the back of the cooling shroud to allow the head to fit. The head is about 1/4" taller than the stock head. There is much more surface to dissipate the heat and the cooling fins are oriented so the airflow stays over the head all the way down. The OS design allows the airflow to disperse before it gets down to the bottom of the head. I run an OS#8 in the main hole and a cooler OS #A5 in the angled lower slot. The idea is to use a hot plug and a cooler plug together to give a smoother powerband and more even burn, also idling is improved and you will further benefit from having a glow plug failure in flight as the other one will usually remain lit in the event of one failing. It is still possible to flame out whether it is too lean or too rich, the dual glow plug design isn't a cure all head. Hopefully, I can keep it happy and not run it too hot, I believe you have to be more careful running a dual glow head too lean as it could really get hot from the dual plugs under a lean condition at high RPMs.

Above is another angle of the Belwood Dual Glow Head. You only need to light one plug to start the motor.

Here's a shot of the head from the bottom, you can see how tall the head is and the horizontal layout of the cooling fins.

Here's a view from the lower left side.

Here's the Bellwood OS-91 Head and BackPlate Heatsink before installation.

To make the backplate heatsink fit the Fury, I had to bascially cut the heatsink in half and only use 3 of the 6 cooling fins. The only other option was to remove the lower framebrace which I chose not to do, as a matter of fact, I doubled the frame brace. I bought one from Ron Lund at a recent Funfly for two bucks because it had a hole drilled wrong... I think it will make the frame even stronger by doubling its thickness. This also hets my Muscle pipe a little further away from the landing gear strut.

This shot shows how the head is made. The second plug is machined at an angle at it is on the left side, the other hole is in the center of the head. You run your normal plug in the center hole and run the cooler plug in the lower angled hole.

This photo shows the combustion chamber of the head, you can see the hole on the right is the angled hole where you run the cooler plug. The top hole is straight down but is slightly offset of true center.

More to come soon!

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