K&B Sportster

[Motorman]

Anyone using the K&B 65 sportster in a stunt ship?


MM

[Dennis Toth]

I think the drawback to the motor is its weight. That whole series would be great because you can rotate the cylinder to point the exhaust to either side or rear. It seems they are built to be driven into the ground from 300 ft by the R/C guys. If you could find a way to get it down to say 12 oz for the base engine would likely be a good high speed low pitch setup.

Best,       DennisT

[rustler]

The S.L.O.P. guys drastically reduce the weight of the K&B 21 Sportster. Probably the same can be done to the 65.
Not sure about suitability for stunt.

[Tim Wescott]

S.L.O.P?

Somehow the idea of using a 65 in a high-speed, low-pitch setup just doesn't work for me -- it seems like it'd be hard to get the power down enough.

[dennis lipsett]

S.L.O.P?

Somehow the idea of using a 65 in a high-speed, low-pitch setup just doesn't work for me -- it seems like it'd be hard to get the power down enough.

The K&B Sportster line behaves more like a 4 cycle than a high speed 2 stroke. I routinely used 14/5 inch props of the 65 and with a diesel head an 18/6 inch prop. The 28 usually sees an 11/4 prop and does a great job of flying a Primary Force. I used an 11/7 on a Sportster 28 diesel in my R/C days for shock effect and it never let me down. Had the engine for a little over 10 years until I converted it back to glow and it quit in a reverse wing over at the top of the maneuver. It hit the asphalt and was trashed.
Still have quite a few of them but probably will never get back to them to use. a Fox 19/25 venturi nva assembly is a drop in to convert it for C/l on the 20/28 engines.

Dennis

[rustler]

S.L.O.P. - S.L.(ow) O.(pen) P.(ower) - maybe just a Brit. event. Open F/F power. PB engines up to 0.21c.i./3.5cc engines.

[Andrew Hathaway]

I thought the purpose of the Sportster 65 was to power RC foamy Mig gunnery target drones.  It seems like the bulk of them out there were salvaged from the drones.

The problem I always run into with any of the "other" engines, that may be less popular or simply unknown quantities, is that I don't want to take the time to build a real stunt plane around an engine that might not work.  I'd rather spend that time building for an engine I know will run well and work out in the end.  The engine is the cheap part compared to the time and raw materials spent building a 60 size stunt plane.

[dennis lipsett]

I thought the purpose of the Sportster 65 was to power RC foamy Mig gunnery target drones.  It seems like the bulk of them out there were salvaged from the drones.

The problem I always run into with any of the "other" engines, that may be less popular or simply unknown quantities, is that I don't want to take the time to build a real stunt plane around an engine that might not work.  I'd rather spend that time building for an engine I know will run well and work out in the end.  The engine is the cheap part compared to the time and raw materials spent building a 60 size stunt plane.

Andrew,

It is true that the  K&B 61 was used in the foamy drone target program after the HB61  and HB ceased production. Carl Goldberg  also had the contract for the foam drones for awhile. But that was not the purpose for which the engine was designed, just one of the applications that the engine was used for. As for stunt even though it is a great engine with a lot of grunt I seriously doubt that anyone would use it or consider it for a stunt model. At 19 oz without the muffler it is dead in the water for any ones consideration. Still they were quite an engine that was woefully misunderstood by the R/C community and a major mistake by K&B to produce an engine that needed a break in and 25% oil at the time they introduced it. It doomed the Sportster line to less then stellar acceptance. However it has acquired a cadre of real enthusiasts who know the engine and what it is capable of.

Dennis

[George Hostler]

The K&B Sportster line behaves more like a 4 cycle than a high speed 2 stroke. I routinely used 14/5 inch props of the 65 and with a diesel head an 18/6 inch prop. The 28 usually sees an 11/4 prop and does a great job of flying a Primary Force. I used an 11/7 on a Sportster 28 diesel in my R/C days for shock effect and it never let me down.

Still they were quite an engine that was woefully misunderstood by the R/C community and a major mistake by K&B to produce an engine that needed a break in and 25% oil at the time they introduced it. It doomed the Sportster line to less then stellar acceptance. However it has acquired a cadre of real enthusiasts who know the engine and what it is capable of.

Dennis, I appreciate your keen observations and experiences with sport Schneurle engines as well as cross scavenged engines. I've always wondered about why K&B would attempt a technology that was somewhat fragile toward abuse. It reminds me of the Chevrolet engineers who decided upon a Chevy Vega that used chrome plated aluminum block for sleeving instead of steel sleeves. The average owner did not maintain oil and coolant changes as prescribed which drastically shortened the life of the engines, giving the car a bad reputation of unreliability.

Thus, 18% oil mixes with the K&B was sure to doom it on the first lean run. Use of a chromed plated aluminum piston running in an aluminum cylinder was a bit unusual. It is amazing that these engines run well on wider diameter props of low to moderate pitch. I'm taking your advice on using added Castor same as with the Fox and McCoy iron piston in steel sleeves for running these engines.

[Motorman]

I bought the Sportster to make a mono line speed trainer that never happened so, I'm just wondering what to do with it. Target drone engine lol maybe I should get it running on the stand and blast it with a shot gun.

MM

[Andrew Hathaway]

I bought the Sportster to make a mono line speed trainer that never happened so, I'm just wondering what to do with it. Target drone engine lol maybe I should get it running on the stand and blast it with a shot gun.

MM

Or for maximum authenticity mount it to a styrofoam cooler with some random servos and RC junk and mow it down with an M16 or M60 machine gun. 

[George Hostler]

I bought the Sportster to make a mono line speed trainer that never happened so, I'm just wondering what to do with it. Target drone engine lol maybe I should get it running on the stand and blast it with a shot gun. MM

Some are now flying stunt with the heavier 4 cycle engines. In the right airframe, perhaps a shortening of the nose to accomodate its heavier weight, or adaptation of the earlier stunt airframes with heavier ignition engines, revision of airfoils, etc., wouldn't the Sportster .65 prove to be a decent stunt engine?