My mate has a 1953 OS .35 Max III that runs and starts perfectly.  I have a "new" one that I have been planning to use as a sport/engine. Is it posssible to get The Max III to run as well as a Brodak .40? If not, why not?

    The Brodak 40 is not a modern engine the way most people think of it, it is a "neo-retro" engine, mostly intended to replicate engines like the Fox 35 (it started as the Double Star 40 and appears to be made by the same people in the Eastern Block, although there have been some improvements since the beginning in maybe 96). You will get only a modest performance increase over a Max III in some cases. The Brodak will probably last longer if you get a good one. A Fox would probably be an improvement over the Max III, probably slightly more performance but will definitely last longer, particularly the conrod.

   If that is what you are comparing, you won't see much difference.

 Modern engines are the OS 40/46VF, PA series, RO-Jett series, OS20/25FP, etc.   

   If you are sport-flying and not interested in competition, almost anything you can get to run reliably is OK. I think you will find that engines like the 25LA are a lot more reliable and bulletproof, and give more performance that much larger engines, but that might not make much difference in the results.

      Brett

     

      Hi:

      Thanks for the prompt replies!

      I checked some old engine tests and noticed that the Fox .35 Stunt produced .45 hp. and the OS Max III produced .67 hp.  To me, this is significant!

                                                                                                                               Be well,

                                                                                                                               Frank McCune

Frank,
Back in the day we were all brainwashed into thinking the 4-2-4 was the only way to fly stunt, today the low pitch/high rpm approach works better than the 4-2-4 for tough wind conditions. Some of the old combat/rat engines like the K&B 35, Fox 36X BB, Veco 35C, McCoy 35 Series 21 have torque curves that peak around 10 - 11K. These engines could run a 4 ish inch pitch running 10 - 15% nitro in a rich 2 cycle and uniflow tank setup will strongly pull quit a large ship in the tough winds. It will work fine for Classic, N-30, OTS. For top level PA at national level you need a modern setup.

The Max III torque curve peaks out at around 9K like the Fox 35 & McCoy 35 Red heads and will not get to the 4 inch pitch especially with a muffler, you still need a 5 -6 inch pitch. But for stunt heaven conditions the old 4-2-4 still works fine (not to long ago the World Champion use an ST 60 in a 4-2-4 setup).


Best,    DennisT

What? Nobody cares about seamed nylons??
 

       Hi All:

       The OS Max III .35 came out in 1959 I think.  I will check that and if I am incorrect, I will post again.  My mate bought his as a preteen while living in South Africa about that time.

        Yes this engine does indeed have  peak torque  about 9000 rpm. and max hp. at 14,500.  I have learned that some engines just like to run in a wet 2 cycle with about 5" pitch props.  My HP .40 engines appreceiate that method of operation.  Sometimes, I  use a 4" prop to slow the air speed a bit.  A 6" prop is very fast with the HP engines.  My mate is using a ST G20/.19 with a 7-6 or 7-4 prop on a plane that is similar to a Blue Pants.  He runs it ar a very fast 2 cycle and it is a pleasure to watch and hear the ST run.  I appears the the older ST engines were a very good engine.  Then there was the ST G21/.35!
 
        For cowpasture flying, ther is something about using these older engines from our romatic past.  All of the horrible experiences that we had in the 50's seem to be conquered by our knowledge today. Lol

                                                                                                                                     Be well,

                                                                                                                                     Frank mcCune


 


    Iam guessing that the .46 proved to  be the best engine in that group.  Tell me about the SF clone.  I have a "new" Sf .46 that I  am getting ready to break in.  I hnope to power a Score with it.


 


 

Tell me about the SF clone.  I have a "new" Sf .46

Royal 46


Measured the Timing , looks maybe good for stunt. 140-110, 40-45 . ,
ST silencer bolt patterns close enought to fit , the merco on it .





The General Theory is things have improved since Ford started using computors to anaylise suspension / steering , with the GT 40 .
Met a guy whos ' career ' is designing radiator cores for Jaguar . ( Theres another for the tanks - No , thats someone else ) This may be taking it a bit far .
Basic configurations had been mastered before WW1 !  Pugeot 4 valve twin cam , etc .

http://theoldmotor.com/?p=139509

Some of these ' antique ' engines would be fantastic with modern metalurgy . Like Magnesium .  (  ) such as the Super Tigres built by Stalker .

My opinion is lower revolutions allow more time for complete combustion , and should be more efficent ( particularly in respect to TOURQUE )than modern G P ish
snot reving shite boxes . after all , the Morris Minor was tested at 100 mph & 100 mpg . ( apparently there were a few complaints when they wouldnt . 

a stunt organised by Morris Motors back in 1931, when a supercharged single-seater side-valve Morris Minor was specially prepared with the intention of achieving both 100 mph and 100 mpg. Driven by von de Becke (who is remembered for his Becke Special using a supercharged aged Wolseley Moth engine in a GN chassis) the racing Morris Minor was timed over the flying-start kilometre at 101.96 mph and over the fs mile at 100.30 mph at Brooklands in October 1931, being given BARC Certificates Nos 2469 and 2470 to confirm it.

The supercharger was then removed and the car was driven round a lenient circuit of public roads in the Midlands, and by judicious coasting and low speeds, a consumption of 107.4 miles on one gallon of petrol was accomplished. It was thus possible to celebrate the advent of the lowest-priced of side-valve Morris Minors with the slogan; "100 mph, 100 mpg, £100".

Even Aston Martins are mass produced plastic trash these days . tho theyre pretty quick .

What? Nobody cares about seamed nylons??
 

Nope! I'm a bare leg man myself...heh, heh, heh.   

Jerry

Hello
Here's a pic of my old engine test bead built in the 1980's a real old roughy now hence the distance shot. It has hosted a lot of engines over the years hence the need for alloy pads both sides!. Current is a K&B Sportster 45 has had in order OS 35 , ST G2135, OS Fp40, Enya 45 6001, OS LA 46 Enya 60's 7032 and 7033 .
The Sporty 45 is quite nice for a "new" engine it has a lot of low down torque and runs cool on a 12x5 but is a little porky but heck the model is tail heavy now but wasn't when it started with a 35 back in the Heavy Metal era!

Regards Gerald 

           This is why I am still using my 1971 Lawn Boy mower.  It is a two stroke that has a 19" cut and is very small and light.  It cuts very cleanly and starts on the first pull every time.  Perhaps Brett Buck will inform me how I get the LB to do the 4-2-4 break when the mower engages a heavy load.

      Just like you do with a Fox 35, set the carb to run rich when free-running, you will hear it clean up when you get in heavy grass. It won't actually go into a 4-stroke, but it will run from very rich to lean due to load. Just like a 20FP, except 1/5th the RPM.

      Brett

hello
Reminds me of the old Two Stroke motor bikes like Suzuki GT500 , they sounded real neat when running 'fat' with a slobbering rich mixture but really roared when given everything and things got very exciting fast partly because of the crappy brakes and handling back then! 
Regards Gerald

More I think about spark ignition, more interesting and worth testing it sounds. Maybe I'll try.. L