OS Jet Stream Mufflers

[Dan McEntee]

 
  OK, calling all you old timers out there that would have been around when the subject mufflers were being used!! After almost a life time of searching , near misses, day late and a dollar short efforts, I have come up with a couple of OS Jet Stream mufflers. I remember reading about these and seeing them on classic era models in the magazines, and then when i started in the even hack in the mid '80s (DAMN that seems SO long ago now!!) they were discussed a bit here and there. I think Merco mufflers were similar in construction, three pieces of cast aluminum in a sorta torpedo style chamber. I have  Merco .40 that I have to dig out and see what's in there.
 
   I'm interested in what the history of the muffler is. they look like they were intended for the OS MAX .35-S engine, but I'm not sure if they fit anything else as they are stock. In looking at my stash of .35-S engines, some of the exhausts have been untouched and some have been drilled out. I'm assuming that they all came from the factory with female threads just inside the stack, and anything else was don't by the engine owners. In looking at it, I found that these can be mounted either way, which will be handy. These things seem pretty rare, and they rarely come up on the usual sites for sale. I have a couple of Nobler ARF models I have been fooling around with and one has a .35-S engine in it, so i tested the muffler on it yesterday. I had been running a home made tongue muffler that I made for the .35-S engine way back in my Intermediate days that is a bit longer than most , and not too restrictive, and the engine runs very well. I put up two flights to make sure I had a good needle setting and then swapped out the muffler, and was pleased to see  almost the exact same reading on the tach when the engine started. The tongue muffler really  sprays the exhaust goo around, and the Jet Stream looks  like it's more concentrated, so maybe clean up after flying will be easier!!

   So, who all used the Jet Stream out there back in the day?  It seems they didn't make these for very long, and if the next engine in the lineage of OS .35 engines was the FP, then that would have interrupted the production of them. I have some more OS.35-S engines in my stash, including some Tom Lay specials that I hope to use in some classic models in the future, and one of these will look really nice on the Novi-IV I have always wanted to build!!

   Type at you later,
    Dan McEntee

[Brett Buck]

   So, who all used the Jet Stream out there back in the day?  It seems they didn't make these for very long, and if the next engine in the lineage of OS .35 engines was the FP, then that would have interrupted the production of them. I have some more OS.35-S engines in my stash, including some Tom Lay specials that I hope to use in some classic models in the future, and one of these will look really nice on the Novi-IV I have always wanted to build!!

  I don't have one and don't know where to get them, but one thing we noticed was that they spewed oil absolutely everywhere, as bad or worse than open exhaust. That how Peter Deane got his nickname - "Greasy Pete".

     Brett

[Paul Pomposo]

My purple twister had one of those in the ‘80s. It wasn’t long before it split in half and projected itself across the grass field. Ted and I spent an hour searching for this in the grass.

[Rusty]

http://sceptreflight.com/Model%20Engine%20Tests/OS%20Max%20S-35%20and%20S-30RC.html

[Trostle]

I have experience with the OS 35S from around 1964 through 1971 and ran them with the Jet Stream Muffler.  There is an internal baffle towards the end of these mufflers and an insert could be placed in that baffle which reduced the noise but reduced power as well.  Also, the another insert could be placed in the muffler outlet with the same results.  Using both inserts, there would be even further reduction in noise and power.  However, with this set up, I was able to practice in a parking lot across the street from the base hospital where I was stationed with no problem with the noise.  I used the OS 35S on my semi-scale Focke Wulf design during this time (MAN, Nov 68) that placed 5th at the 66 Nats, 5th at the 68 Nats and 1st at the 70 Nats.  To my knowledge, this was maybe the second time a stunt model with a muffler won the Nats.  Bob Gialdini may have been the first based on a photograph in Wynn Paul's Stunt History with Gialdini posing with his Nats winning Veco .45 powered Eclipse that shows some sort of a muffler.  (I have not been able to find any earlier use of mufflers on top placing models at the Nats.  If there is more information, I would like to be enlightened.)

My experience with the OS 35S is that they are not happy with tongue mufflers unless they are drilled out to where there is essentially no muffler.

I think Dave Gierke used the OS .35S when he appeared at the 65 Los Alamitos Nats with his All Ameircan and Novi models.

If you have an OS 35S set up by Tom Lay, you have something that is special.  Treat it well.  The only problem with the OS 35S for this size and class of engine is that the connecting rod has a limited life.

[Dick Pacini]

I seem to recall an upgrade/improvement to the OS 35S was the use of a SuperTiger Rod (which was bushed) and to install brass buttons on the ends of the wrist pin.

[M Spencer]

https://stunthanger.com/smf/engine-set-up-tips/tom-lay-os-max-35s/msg567117/#msg567117 Ere's a Fred with a like to one on the MODS .

The NYLON PAD is for the Back of the Rod . ( a 'T' ) to stop it going CLANG , along with a 'X'filed into the front thrust face . On a Big Art Injun .

One F M thing hadem 300 Degreeing the P & L three times then lapping with tootpaste . So the Top was Pre-Grown , Polishing things too .

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Mufflers 'n 'cases . Theres three ( or four ) Cases . The 'back 'tapped lugs , ditto untapped , and the untapped extending out to near the face .

PLUS theres R/C mufflers with the THING for the rotateing baffle , drilled . And Some Undrilled . and some without the round bit cast in there .
THEN , I Think , Maybe , heres a few differances in the muffler exhaust entry point . ( From a few I have , Four ! . ) PLUS whacking the hole out
so it matches the whole stack hole -    -  You end up slotting the front baffle . tho I suppose a more carefull appoach would be to  LEAVE IT
& knife edge it , opened either side . 

The later '703 strap on came out in the early 70's . Worth notching the bolt , side mount , as the underslung muffler can tear the lug out on a abrupt arrival .

RANDY SMITH somewhere goes into venturie size for each type - 703 / jetstream -  https://stunthanger.com/smf/engine-set-up-tips/art-adamisin's-os-max-s-35s/msg522121/#msg522121

[M Spencer]

Thats the 703 , with the EXTENSION , Woter availiable for them & those Jetsreams . Or were . Note the BOLTS , and the LUGS .
Might pay to notch both bolts , side mouted undercarrageless . As you can knock out either lug , even the wind sucking it into the ground on the glide / landing .

The JETSREAM ( and THOSE ) Fit the H29R - H 40 series etc & 35C & R C derivative . So may be OUTLET BORE size differances , like on the 703
& little strap on for the 15 , 20 & 25 . ALL tailpipe bores vary to suit .
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A .60 one with the straps ?


coupla pictures of a brand new .60 one . https://www.worthpoint.com/worthopedia/vintage-os-max-jetstream-muffler-60-1799853910 cant gettem on ere .

RIGHT , Model Sports in Dapto has a few NEW OS 35 S C Cases ( which are intercangeable ) the od crank , wrist pin or two Cetra . H29R & 35S runt same rod etc & P/L . According to the packets .
you need the 35 head putting a .35 P/L ineem , of couse .

Just to confuse the issue . THESE usually have C , or maybe R/C onem . Single Ball Race .


Theyre the ; back in - tapped wotsits .



And Fininanally ,  You can see the little 'C'on the COMBAT , which look to have GOOD Stunt Timing .



My , what big teeth you have .  Er , Intake .

oops , WITH the OS 30 S pieces . the 29R  TBR . The HEADS on the 'C '35 are WEDGE , but interchange with the HEMI 35 S heads . Keep things simple , they say . 



The P/L on the ball race 35 WONT interchange , Tho Lapped Iron set up . utterly uninterchangeable .

not Only THAT , but the 703 for the 30 , 35 then 40 , s gotta bigga ole inna da end ( outlet tube ) on the 40 . ( with RC /P.SP/RR / S on case is earlier long stroke . a PLAIN 40 in the coikle , its a latter R C with the later bore / stroke , Which they used from then . FP / LA / FSR like .)
SO 703 mufflers can have varying tail pipe bores .May even have slightly differant inside flange Dimn. , like S Tigre 46 / 60 . bigger slightly for slightly bigger stack . Like 1/32 = 0.8 m.m. differance .
the 704 s the big .60 strap on .