Wulf

My Feedback: (5)

I was just given a new never mounted 1957 Super Tigre G21 .35 size C/L engine-Can anyone tell me anything about this engine and what is the fitting on bottom of crank front housing used for-I assume it`s for pressure but ,Ive never seen one located here-
Appreciate some info on this Italian stallion--

kdheath

Yes, it's a pressure fitting. From that, I expect this is the combat version of the 35. Look into the exhaust. If the piston has a flat top, it's the combat version. If it has a baffle, it is the stunt model. The combat model would be fun in an older design combat model for some nostalgia, but not very good for stunt flying.

Wulf

My Feedback: (5)

It has the baffled piston--Therefore I presume it`s a fairly good stunt engine.I`m I correct in saying that??--
One more ?---Is the tank hooked up with feedline and pressure line only--much like exhaust presurerized RC setups???

R8893

My Feedback: (20)

Wulfman,
Yes you do hook the engine up just like muffler pressure. However it does not operate quite like muffler pressure. Crankcase pressure will pressurize the tank whenever you turn the engine over. Muffler pressure bleeds off through the muffler when the engine is not running, and indeed when you run at low throttle. When starting the engine with crankcase pressure you should squeeze the fuel delivery line closed to prevent flooding. Release the line as soon as the engine starts running. Normally it is necessary to prime the engine to get it to start. The pressure fitting on the bottom of the case gives timed crankcase pressure that is higher than the pressure obtained with a fitting in the backplate. The port in the crankshaft aligns with the fitting when the piston is at bottom dead center and the pressure in the crankcase is at its maximum. Note too that if the pressure line in the tank is below the fuel surface fuel will be forced back into the crankcase through the pressure line. BTW I still run my old ST 35C's and G21-35's on tank pressure; I never made the switch to bladders.
Chuck

kdheath

Here's a link to a fair amount of ST 35 experience:

http://www.clstunt.com/htdocs/dcforu...ID1/10169.html

Sounds like some of what you want to know. Depends on what you want to do with it. Combat or stunt? Sport flying?

Wulf

My Feedback: (5)

My Thanks to all--------

gcb

Around that time Super Tigre switched models. My G21 .35 has a separate crankshaft assembly and crankcase. It came with several intakes. The large one needs the pressure fitting, the others will run on suction.
I also have the G20 .15 that has the same setup except it has two ball bearings where my .35 has a BB in the rear and a sleeve bearing in the front.
I think I remember reading that my version broke crankshafts easily. Not sure about the other versions.

George

kdheath

I think I remember reading that my version broke crankshafts easily. Not sure about the other versions.
George
[/quote]

That's why they didn't make it in combat-under high nitro/highrevs, they broke a lot of cranks. But on mild fuel for sport/stunt, I don't know of any failures.

William Robison

My Feedback: (3)

I ran a ST G21 5.0cc (0.29 cid) in proto speed, nd a G20 (later G21) 2.5cc ia A speed. Never broke a crank, nor did I ever hear of anyone else breaking a crank in one of them.

Bill.

gcb

Bill, I guess I was a little vague in my statement. It was/is my understanding that the early G21-.35 did not make a good combat engine because of crankshaft breakage. I never had a newer version.
My first G20-.15 was the version with the removable front housing. I have later versions of the G20/15 (1960, I think) in glow and diesel. Never had a crank problem with any of them. The G15 and X-.15's I have are still new so I can't speak for those.

Here are the .15 and .35 I was referring to with the removable front end.

George

William Robison

My Feedback: (3)

George:

I'm not certain on the "G" numbers, my first 15 did not, as I recall, have a removable front cover, but otherwise both it and the 29 looked like your picture. The later 15 was physically larger, and the intake was angled to the front.

Bill.

Wulf

My Feedback: (5)

That`s it--my G21 .35 looks like your picture--with bolt on front cover--

gcb

Between my first one and the 1960 version came one called the "Jubilee", I think. I do not have a Jubilee, but here is the 1960 version:

William Robison

My Feedback: (3)

George:

If that engine has an unfinned head it will be the one, so far as I remember. I did get the factory supplied spinner with mine, the factory spinners were no more expensive than the Froom, and they were a lot stronger.

Bill.

tflame

My Feedback: (1)

Hello Wulf
I have one that I bought in 1969 The G21/.35c flat top piston And I just replaced the bearings on it. It always had real good compression and I have used in Combat wings and stunt planes. I`m getting it ready for a Flite Streak ARF. I ran it today on 5% Powermaster 29% castor oil and it hummed. When I got it it came with 2 venturis one for stunt and the other one for combat. I polished the head,venturi and prop drive. The crankcase I cleaned with thinner and I cleaned the outside with some scouring powder and a tooth brush.It looks pretty. Of course I made a new solid fuse for the streak not wanting it to depart the plane. Use it is a great engine.

Yours
Tflame
Modeler since 1963

Strat2003

My Feedback: (1)

Are the flat-top piston versions the ones that had what they called "airfoil ports" on the bypass? I just got a 1972 vintage G21 .29 which I intend to use in B Glow SAM events next year. It has two absolutely huge angled bypass ports directly across from the exhaust.
Mine is a rear-rotor engine. Does anyone have experince with these?

gcb

I think Super Tigre was the first company to angle the ports and remove the baffle. Others soon followed.

George

William Robison

My Feedback: (3)

That was a relatively early variant on the Schneurle porting in model engines, before boost ports were used. The G21 0.15 I had with the unfinned head had the same porting. The G20 0.29, though, had a baffled piston and ordinary loop scavenging.

The patent for the Schneurle porting was issued in the mid 1920s, the ST engines were far from the first to use the system.

Bill.

Jim Thomerson

The later model G20 15's had the smooth piston top, but the G20 19's and 23's made in the same case were baffle piston engines. At least the ones I have seen were.

Jim

gcb

Bill, I think you have your "G" reversed. The G20 was the smaller engines and the G21 were the larger ones.

Jim, I haven't looked into my G20-.23's in a while but I think all of mine have the baffle you mentioned. Mine are RC versions with a plain bearing in front and a BB in the rear (I think). Although I don't have one, I read that the .19 had 2-BB's like the .15. I'll defer to you about the baffle. The first pic is a couple of .23's

Mr. Garafoli (sp?) sure confused a lot of folks with his series numbering system. Some he changed and some he didn't. Here are a G-15 and an X-15.

George

William Robison

My Feedback: (3)

George:

As I said in an earlier post, I'm not sure about the "G" numbers.

I traded the 0.29 for a pair of NIB Max III 0.15 R/C engines about 1970, it was definitely fitted with the baffled piston. Still have the pair of OS 15s, still new and un-run, still in their boxes.

The last ST 15 though, was indeed the flat piston.

Whatever the "G" numbers, and Garafoli (sp?) was very confusing with his numbers.

Bill.

telmore

Can someone give me a chronology for ST C35 and G21/35 motors?

Tony

I thought the g21/35 was later than '57 and that none had baffles!

gcb

I really like the Max-III .15's, they are excellent engines. My first Max was a Max-I .15 (CL). I have a NIB Max-II .15 and several Max-III .15's (CL and RC). It is interesting to see how the carbs and exhaust restrictors evolved over the production life of that engine. Earlier Maxes came as CL or RC. If you got the RC version, they also included CL parts. They also included rubber dust covers for the intake and exhaust. That stopped with the Max-III because it had a true throttle that did not use the CL needle valve assembly.

George

PS Sorry for straying off ST topic.

gcb

I went searching in my engine boxes and came up with an old oil-soaked paper showing parts and prices. There is no print date but in the G21 section a reference is made to the G21Series (62) which MAY indicate 1962. The G21 series (also designated as AA) came in .29, .35, and.40.

The ST .35 Combat is not a G21 but designated S.T. The S.T. series came in .35 combat(CA), .35 stunt(SA), and .51/.56 ring RC(AAA).

The G20 series (also designated as "A" series and Jubilee series) came in .15 (glow and diesel), .19, .23. The parts list excludes front BB for the .19 and .23. It also excludes a pressure fitting for the .15 diesel.

My .15's (glow and diesel) and .23's conform to this (.15 crankcases stamped 1960). Additionally, the .15's have no head fins and no piston baffle. An "A" is stamped in a mounting lug on the .15 glow, not sure if that is a series designation.

My .23's have a baffle but are later models (crankcase stamped 1970).

My older G20 .15 and G21 .35 with the removable front end are both baffle.

I hope some if this helps. I hate to keep typing "My" but since the models changed so much, yours may be different.

George

Edit: Another box, another paper (from 1963). The G21 .29, .35, .40 has 2BB's, The S.T. 35C plain bearing, flat piston, and the 35S plain bearing, baffle piston.

Steve Helmick

My recollection is that the earlier G.20 and G.21 with seperate front housings were baffled piston, but I never owned one. We had a local who had one, and it sounded good, but suffered from needle setting problems when I saw it fly. Maybe a Baby Pacifier would have helped, or at least less nitro or smaller venturi. However, as a NIB engine, I would suggest putting it on eBay and buy something more suitable for your purpose and for which parts are available. Maybe a Nelson.....

I liked the ST .35C Combat engine real well. I had one G.21 .35, but we didn't tumble to the need for smaller props on it. The ST .35C was very much the opposite, a 9-7 was not enough pitch, but it wouldn't pull a full 9-8 well, except on 50% nitro, which made it a bit fussy. I also ran G.15's in A speed, and G.21 .29rv in B and B Proto, and a G.65rv in C speed (D now). The front intake G.15 and .29rv were great engines, the G.65rv much less so, IMO. Steve