Bill Netzeband had been with Testors for many years, however, his advice about engines was mostly ignored. He did design the guts of the Series 21, while Testors called in some outside creative artistry consultants for a visual look that would set their product apart.

The terrible box shape was the result. They wouldn't change it when it didn't sell as well as the old engines (which both Netzeband and Dick McCoy were both trying to tell them), and dropped out of manufacturing engines larger than .049 size.

Incidentally, the Series 21 cylinder and piston were a drop-in upgrade for the older Red Heads.


Kiwi

OkiThumper,

I would defer to "the Kiwi's" comments regarding the external design of the Series 21 engines.

I know I bought two of them based on their looks. They were very heavy compared to other engines of similar displacements.

Regarding the red anodized glow head on the .049-I thought is was really cool looking too!.


The Kiwi,

Great information sir!

I do remember that they were much easier to start with an electric starter, than by hand. There was not much of anything in the way of compression, on the ones I owned, and they lacked a properly tapered collect or keyway at the front of the crankshaft where the propeller backing plate was. No amount of tightening could keep the propeller from coming loose (again, I have a sample of two to work with).

I always heard that the added weight/fins to the Series 21 were purely cosmetic. I did have an S21 40 that ran great! It had a dykes ring and after reassembly the engine had extremely low compression until the dykes ring could seat effectively.

Originally Posted by Ah Clem

Great information sir!

I do remember that they were much easier to start with an electric starter, than by hand. There was not much of anything in the way of compression, on the ones I owned, and they lacked a properly tapered collect or keyway at the front of the crankshaft where the propeller backing plate was. No amount of tightening could keep the propeller from coming loose (again, I have a sample of two to work with).

The Series 21 were ringed with the same type ring that K&B was using -- called a Dykes Ring. There was some trick, like carrying STP in an injector, or something else of similar weight to amp up the compression for hand starting. I never owned one, however, I'd bet that the same trick that worked for Red Heads would have helped the Black Head motors to grip a prop.

The thrust washer only had dimples on it that couldn't get a grip on maple, nylon, or other harder composition props, but the thrust washers from K&B's GH 35 and 45, plus late model GH 29s, with the sharp edged teeth, fit the RHs perfectly. I'd like to have such a thrust washer now as a spare to use on the McCoy 40 RH that I still have.


Kiwi

Originally Posted by gcb

This one is from an RTF. If I remember correctly, it was a P38 with one powered and one dummy engine. I have some of the plastic ones...they were designated Testor's 8000. I'm guessing the name was because .8cc is .049ci. They are affectionately known as "pipe bomb" engines.

Not sure where the term, "pipe bomb" came from. Perhaps the zip gun manufactured method of the plastic crankcase block?

I have one metal bodied one that came in an RTF space craft...don't remember the name. That's the one on the right, by itself. The ones with a tank are oriented for CL with the cylinder pointed horizontal left (from the front). The engine was marketed with the engine upside down in the box. It came with a prop, wrench, and needle extension.

gcb, this is good to know. I have one of those Testors engines with carbon fiber crankcase and tank. If I am flying R/C then, the head should be down with refill tube along the top; if C/L, the head should be horizontal with refill tube vertical and open end up, correct?

Originally Posted by The Kiwi

Bill Netzeband had been with Testors for many years, however, his advice about engines was mostly ignored. He did design the guts of the Series 21, while Testors called in some outside creative artistry consultants for a visual look that would set their product apart. The terrible box shape was the result. They wouldn't change it when it didn't sell as well as the old engines (which both Netzeband and Dick McCoy were both trying to tell them), and dropped out of manufacturing engines larger than .049 size.

This is an unfortunate marketing decision. I would have much preferred the Red Heads over the Series 21's. Several years prior (early 1970's), I bought a McCoy Red Head .19 stunt engine from America's Hobby Center on sale for $6. A few years later, I bought around a half dozen Series 21 engines, 29's and .40's for around $5 apiece on clearance at a local hobby store. The only one I have left now is one .40. I have a Dubro stack spring baffle muffler somewhere, was thinking of possibly building a Ringmaster for it.

Incidentally, the Series 21 cylinder and piston were a drop-in upgrade for the older Red Heads.

This is good to know, might come in handy with some vintage C/L models.

Originally Posted by tigreflyer

I always heard that the added weight/fins to the Series 21 were purely cosmetic. I did have an S21 40 that ran great! It had a dykes ring and after reassembly the engine had extremely low compression until the dykes ring could seat effectively.

That's what I gathered the reason for the odd engine shape. Unfortunately, Testors' management apparently didn't understand marketing with modelers. Modelers don't look for fashion statements, they look for economic prices and performance.

"gcb, this is good to know. I have one of those Testors engines with carbon fiber crankcase and tank. "

The black crankcases were actually glass filled nylon-carbon fiber was not around yet.

There are two versions of this engine for the Fly'em Plastic RTF airplanes, that I know of:
1) The earlier version, which was actually a front rotary valve and had a nylon mixture control instead of a needle valve. This was on the early versions of the Fly'em aircraft
2) A later version with a reed valve and normal needle valve. These are the ones we were supplied with for the demos.

The earlier ones had an aluminum crankcase, the later ones had the glass filled nylon. There may have been some overlap of materials, but the actual tooling was different.

Both ran well, but I seem to recall the later ones running stronger than the earlier ones.

The reed valve ones were later sold with an integral fuel tank, so that they could be used outside of Fly'em aircraft.

The engine that came in the Galax IV (the final version of the old, Wen Mac hovercraft), appears to be a reed valve engine with a separate tank.

Lots of variations/changes over the years.

Originally Posted by OkiThumper

Not sure where the term, "pipe bomb" came from. Perhaps the zip gun manufactured method of the plastic crankcase block?

I had assumed it was the crankcase shape.

gcb, this is good to know. I have one of those Testors engines with carbon fiber crankcase and tank. If I am flying R/C then, the head should be down with refill tube along the top; if C/L, the head should be horizontal with refill tube vertical and open end up, correct?

I have not used these for RC but I would assume that also. Yes for the CL position.

On the Series 21 McCoys, the only ones I have are two CL .19's. One has been run and the other is still NIB. Someday I hope to get around to using them in ships.

The idea of the Dykes ring is to be loose when going up and seal well after combustion. For that purpose they are "L" shaped. My guess is that running at the RPM we use them, the dykes ring probably assumes a more constant seal. In any case, they seem to not have a lot of compression when turning them over by hand but they run well.

George

That was common on the K&B .40R/C; the early/middle 70's engines, p/n 8011 like mine is, used a Dykes ring and the low compression happens only when hand flipping. I was told when you ran the engine, combustion pressure sealed the ring against the cylinder walls, improving compression only when running. Whatever the explanation, my K&B engines, along with my Red Head McCoys, ran (run) good enough for my non-competitive flying. Smooth and reliable for years.

I've got a Testors .049 with the plastic crankcase, as installed in a Testors BD-5 ukie. Was always concerned about overheating the engine and melting the case. Wonder how far the cylinder would have traveled

"I've got a Testors .049 with the plastic crankcase, as installed in a Testors BD-5 ukie. Was always concerned about overheating the engine and melting the case. Wonder how far the cylinder would have traveled"

Interesting.

When we got the BD-5's, they told us not to let it sit on the ground running as it would destroy the engine (so I think you were very wise, sir!).

Originally Posted by Ah Clem

When we got the BD-5's, they told us not to let it sit on the ground running as it would destroy the engine (so I think you were very wise, sir!).

Interesting, then this fiberglass epoxy matrix crankcase engine is best left without any type engine cowl enclosure, such as many 1/2-A profile and balsa log fuselage models and front mounted, where the prop provides additional cooling.

"Interesting, then this fiberglass epoxy matrix crankcase engine is best left without any type engine cowl enclosure, such as many 1/2-A profile and balsa log fuselage models and front mounted, where the prop provides additional cooling."

They were pretty well cowled in on the Fly'ems. The Zero especially. They also came with mufflers installed, which increased the head.

The issue on the BD-5 cooling was that is was a pusher, so no air flowed over the cylinder unless the ship was moving forward.

Again, it was glass-filled nylon, not an epoxy matrix. CF was still in the future and Testors would not have opted for that from an expense standpoint.

Originally Posted by Ah Clem

They were pretty well cowled in on the Fly'ems. The Zero especially. They also came with mufflers installed, which increased the head. The issue on the BD-5 cooling was that is was a pusher, so no air flowed over the cylinder unless the ship was moving forward. Again, it was glass-filled nylon, not an epoxy matrix. CF was still in the future and Testors would not have opted for that from an expense standpoint.

Thanks for the clarification, Ah Clem. Having never disassembled one, just curious, but do they have say, bronze bushings for the crankshaft?

A little extra info...the starter used on later McCoys were on Wen Mac engines. I believe Testors purchased the Wen Mac company to get the starter. Anyone know more about this?
Here is a WenMac II from a Aeromite.

George