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Author Topic: OS .40 4 stroke?  (Read 11849 times)

Offline david beazley

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OS .40 4 stroke?
« on: October 29, 2010, 06:19:10 AM »
I have an old OS .40 4 stroke.  It is one of the first generation non-surpass.  Anyone used one for CL?  Any feedback is appreciated.
It's only paranoia if they aren't really after you.
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Offline Andrew Tinsley

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Re: OS .40 4 stroke?
« Reply #1 on: October 29, 2010, 08:53:09 AM »
Hi,
  Not too familiar with 4 strokes, but if it is the very early type with exposed rockers, then it is very definately no good for stunt. I had one and it just about pulled the skin off a rice pudding! They make beautiful power plants for old timer fying with a little radio assist. They just purr along and make a delightful noise. Wished I hadn't got rid of mine. I used it on new planes before putting in an old sparker, just to get the trim somewhere near. That way I only had one problem at a time!

Regards,

Andrew.
BMFA Number 64862

Offline Robert Zambelli

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Re: OS .40 4 stroke?
« Reply #2 on: November 04, 2010, 12:59:30 AM »
David.
I was not aware that there was an open rocker version of the 4-stroke OS 40. ENYA 40, yes.

I have a few of the versions that came just before the Surpass. Closed rockers, small pushrod tubes. They are marked "FS 40" on the exhaust side of the case.

They are absolutely some of the smoothest and most consistent running engines I've ever owned.
They do not make the power of the Surpass but what they do make is plenty. I flew one on the prototype ARF Cardinal (Just over 50 ounces) for many years and let everyone try it. The runs were PERFECT. I tested it with a variety of props and found something that I had never seen before. It just wanted to run at one speed. With props from 10-6 wood to 11-8 plastic, it ran at the same speed.  n~ n~
The fuel of choice was Powermaster 20/20 with 2% castor added.

The Surpass 40, on the other hand, I just could not get to work. It was incredibly powerful but as inconsistent as could be. Without touching any settings, I could make ten flights in a row and not get two runs the same. I tried everything - different props, fuel, plugs, tanks. Nothing worked. It was run in exactly per the instructions. Valves were right on. Also, it required over five ounces of fuel for the pattern (The non-Surpass version needed two).

Finally, one day after starting it, while walking to the handle, I heard a "BANG" and it stopped.  ~^ ~^  Stopped instantly. I could turn the prop around 3/4 rev each direction and it hit a hard stop. Turns out the crankpin broke and was driven partway through the bottom of the case. Also bent the rod, distorted the piston and damaged the sleeve. I was actually happy that it self destructed. Good riddance!!!!  LL~ LL~  #^

Bob Z.

Offline david beazley

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Re: OS .40 4 stroke?
« Reply #3 on: November 05, 2010, 01:43:28 PM »
Bob,
That's the one I have, enclosed rockers, first generation OS .40.  The first OS .60 had the exposed rockers.  That is the one Maynard Hill set his world records for RC with and flew across the Atlantic as well.  I could never get it to run well with muffler pressure on a clunk tank in RC but runs like a dream with no pressure.  I am starting a Brodak P51-B and was thinking of trying the 4 stroke on it.  Do you think it would work on the P51?
It's only paranoia if they aren't really after you.
Analog man trapped in a digital world
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Offline Robert Zambelli

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Re: OS .40 4 stroke?
« Reply #4 on: November 07, 2010, 06:45:38 PM »
David - I'm not familiar with the Brodak P-51.

Is it a copy of the old Sterling kit? If so, NO GOOD!!! Way too much engine.

I flew one for many years with an OS 26 4 stroke.

I would suggest the Brodak P-40.

Bob Z.

Offline david beazley

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Re: OS .40 4 stroke?
« Reply #5 on: November 10, 2010, 05:19:41 AM »
Bob,
I don't think the Brodak is the same as the Sterling.  The Brodak has a 470 sq/in wing and lists engine sizes .28-.40.
From what I have seen the Sterling had a 38" wing span and the Brodak is 46".  Maybe someone out there in CL land knows better than me.
It's only paranoia if they aren't really after you.
Analog man trapped in a digital world
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Offline Robert Zambelli

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Re: OS .40 4 stroke?
« Reply #6 on: November 11, 2010, 05:52:46 AM »
Hi, David.

If it were my situation, I would put it on a plane of at least 54 inch span.

Although not a powerful as the Surpass, this engine will make more power than most of the 2 stroke 40s.
I would look at planes designed around the 35 to 46 engines, like the P-40, Profile Pathfinder or Thunderbird. If you like Old-Time, the Viking is a fine candidate.
Keep in mind that the 40 FS is heavy, weighing around 12 ounces. Because of this, you will need to shorten the nose accordingly - the alternative of course, is to add lots of tailweight. Use of a lightweight prop and spinner will help.
Most of my flights required two ounces of fuel but you should allow for a three ounce tank just in case. Try the Hayes three-ounce clunk tank.
Let me know if I can be of more help.

Bob Z.

Offline david beazley

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Re: OS .40 4 stroke?
« Reply #7 on: November 11, 2010, 06:02:25 AM »
Thanks Bob for your input.  I guess I will rethink the installation on the P51 project and save the OS for a more appropriate project.
It's only paranoia if they aren't really after you.
Analog man trapped in a digital world
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Offline Dennis Vander Kuur

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Re: OS .40 4 stroke?
« Reply #8 on: November 12, 2010, 09:29:24 PM »
Here in the midwest Jim Schuett runs an OS .40 four stroke (pre Surpass model) on a Twister. It pulls the plane around very well. I remember he used it to win the PAMPA Expert event at the Milwaukee, Wisconson contest a couple years back when it was so windy he didn't want to chance flying his full blown stunter.
DennisV
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Offline david beazley

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Re: OS .40 4 stroke?
« Reply #9 on: November 13, 2010, 06:59:20 AM »
I have a Twister kit that is next in rotation to be built.  Looks like that is where it will go.
Thanks!
It's only paranoia if they aren't really after you.
Analog man trapped in a digital world
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Offline Mike Lauerman

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Re: OS .40 4 stroke?
« Reply #10 on: December 17, 2010, 12:52:11 PM »
I ran an OS .40 non-surpass in 1984. Ron Sheldon's Hobby Shop got 2 in, and I bought this one for $90.
I installed it on a scratch built profile biplane I built for test purposes, to satisfy my dilemma with top wing incidence. (top wing was incidence-adjustable) 36" wingspan, 28" fuse length, silkspan/dope finish.

Adhering to the old rule "just one adjustment at a time", I was cautious to bench run the engine prior to installation. An associate and I took turns running it just outside the Service Dep't at Allison BMW, where we worked. After 8 tankfuls of 6 oz., I was satisfied with its performance. Consistent as could be, only it would backfire on starting and lose the prop nut! (the cleanliness of the area was tantamount in recovery of that nut! In desperation, I simply applied a length of silicone fuel hose to the end of the threaded crankshaft. Never loosened it again. It was as though the nut 'took the hint'!)

11/5 Top Flite prop, 10% Sheldon's fuel. The plane balanced a trifle nose heavy, and seemed to weigh a ton...
I took off with the throttle blocked wide open, engine not 'screaming', just making unbelievable prop draft...It taxied for 1/4 lap, I held 'down' to raise the tail; when I gave a little 'up', the plane caught up to the engine.
Climbs, dives. The first wingover gave no hint of engine strain, it didn't lose ANY RPM! It was effortless!
Took some getting used to, but when I tried the "C/L Immelmann" (at the top of the wingover, crack full down)
the Bipe did a quick roll, swooping downward, then doing a slow loop (on its own, 20 ft. slack in the lines!) then returned to the end of the lines at about 20 ft. up, gently wagging and returning to that super smooth constant!
I would fly that plane over that year, then again in '86 & '87.
I got my final adjustment figures, (wasn't that far off with incidence) and received all kinds of "advice" and other verbal insubordination... ("4 strokes don't work for C/L", etc.) but I enjoyed the plane, to this concensus: The 4-stroker never gave me any trouble, besides the occasional backfire starting. Its performance and consistency left plenty of carefree room to get to the purpose of the airplane: the tests.
Heavy, yes. But not too heavy on the lines. It did land a little fast... 

Offline dennis lipsett

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Re: OS .40 4 stroke?
« Reply #11 on: December 20, 2010, 06:49:20 AM »
Hi, David.

If it were my situation, I would put it on a plane of at least 54 inch span.

Although not a powerful as the Surpass, this engine will make more power than most of the 2 stroke 40s.
I would look at planes designed around the 35 to 46 engines, like the P-40, Profile Pathfinder or Thunderbird. If you like Old-Time, the Viking is a fine candidate.
Keep in mind that the 40 FS is heavy, weighing around 12 ounces. Because of this, you will need to shorten the nose accordingly - the alternative of course, is to add lots of tailweight. Use of a lightweight prop and spinner will help.
Most of my flights required two ounces of fuel but you should allow for a three ounce tank just in case. Try the Hayes three-ounce clunk tank.
Let me know if I can be of more help.

Bob Z.


Bob,
I find the sentence saying that the pre Surpass will make more power then most 2 stroke 40's interesting. Remember this engine came out at a time when 4 strokes were never rated at the power potential of contemporary 2 strokes. Even 120's were rated at the power of a 60 and could be used in lieu of a 60 2 cycle. I certainly ran everything and can attest to the fact that statement is true.
Perhaps it really does reinforce just how litte raw power is needed for stunt rather then controlled power. But, to say that it was that powerful at that time and with the competition it faced with very good to excellent 2 cycles at that time period has given me a singular moment of amusement.
« Last Edit: December 20, 2010, 10:21:49 AM by dennis lipsett »

Offline david beazley

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Re: OS .40 4 stroke?
« Reply #12 on: December 20, 2010, 05:36:59 PM »
The .40 in question was bought in the early '80's.  I had purchased it shortly after getting into RC. (sorry guys but no one I knew at the time was flying CL).  I used it interchangeably with a ST .25ABC engine.  The ST seemed to give more power but the OS had the Wow factor.  It always ran like a Swiss watch.
It's only paranoia if they aren't really after you.
Analog man trapped in a digital world
AMA # 2817

Offline Robert Zambelli

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Re: OS .40 4 stroke?
« Reply #13 on: December 21, 2010, 12:15:57 PM »
Actually, I should have been more clear.  :'(    The watchword should be performance, not power.
What I should have stated is that the non-Surpass 40 flies a plane as well as or better than ALL the 2-stroke 40s I compared it to.
I have a plane that I built exclusively to test and compare engines. A simple profile with a Viking wing.
I have flown it with powerplants from a SAITO 30 to a SAITO 56, as well as just about everything in between.
Brodak 40, FP 40, OS 40H, ST 40 and on and on. Also, Surpass 40, 48 and 52. Enya 46.
Two and three Surpass 26s.
Comparing performance (line tension, wind handling, smoothness, ease of control, etc) the OS FS40 performed better all the two stroke 40 size engines I tested.
It also was the quietest and most economical - 2 ounces for the pattern.
I did not compare it to any of the high-end 40s like the PA or Double-Star as I did not have access to them.
I then put the FS40 on the prototype ARF Cardinal and brought it to five or six Brodak Fly-Ins. I let EVERYONE fly it and most of them said it was the best profile they ever flew.
Yes, we even flew it at night.   y1

Regarding absolute (measured power), as I recall, the Super Tiger 15 is rated at just a bit more horsepower than the Olhsson & Rice 60.
But, put the ST 15 on a six foot free flight plane and see what happens   LL~ LL~

Bob Z.

Offline Bill Little

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Re: OS .40 4 stroke?
« Reply #14 on: December 21, 2010, 02:24:29 PM »
Hi Bob,

I am sure you are familiar with the Brodak P-51"B" that is being talked about.  it was Mike Garmon's first "Warbird" that John kitted. (Shortened GB Nobler wings)  AS you know the first series all used the same wing, different fuselage stylings.  Mike told me he removed R-1 and went from there for the wing.  I built the Zero prototype, from Mike's pencil drawings (which I still have! ;D ) for John.  (I had to build a new wing for mine....... :( )

I have flown Mike's original (Steve Fitton has it) with a K&B .40, the non ringed one John sold for a short time.

I think from what you have said, the OS .40 four stroke in question would be great for it!
Big Bear <><

Aberdeen, NC

James Hylton Motorsports/NASCAR/ARCA

AMA 95351 (got one of my old numbers back! ;D )

Trying to get by

Offline Robert Zambelli

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Re: OS .40 4 stroke?
« Reply #15 on: January 20, 2011, 08:15:21 AM »
Back to the OS FS 40.   y1 y1
I mounted it on the Brodak P-40 ARC prototype and what a pleasant surprise!
At 49 ounces, it flew perfectly with a 3 ounce Hayes clunk tank.
I like this engine more each time I use it.  #^ #^

I do remember in the past on another website, someone stating that this engine was a waste for CL stunt, or something to that effect.
All that told me is that he may have tried one and was probably too dumb to figure out how to make it work.  LL~  LL~

It's really a fine powerplant and very reasonably priced at swap meets - I've found them for as little as $20.00.
Also, I've never seen one break.

Contact me if you need more info.

Bob Z.


Offline Phil Spillman

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Re: OS .40 4 stroke?
« Reply #16 on: April 01, 2011, 07:34:27 PM »
I've used both the OS .40FS and the Surpass models on an Old Time Dragon Stunt plane. The pre-Surpass ran very nicely and steadily but didn't have enough power for me. I then mounted my Surpass .40 and used a Zinger 11 X 5 wooden prop and a venuturi made for me by a close friend. The venturi featured ST NVA parts and has worked quite well until I pranged the plane thanks to a pine tree in Huntersville,NC and then really heavy winds in 2009. The Surpass engine was run using a wired open rc throttle in a Humongous given to me by the late Willis Swindell. My own engine didn't perform well in this set up so Willis lent me his own Surpass .40! It ran quite well for me until i replaced it with an LA .46 which ran much better for me!

In my experience four strokes are tempermental little beasts which will surprise you once in a while with fine runs and frustrate you more often! In all instances I used the YS 20/20 blend and always use good after fun oil. I have used both ATF and Air Tool oil as after run oils.

Saito Engines generally are more user friendly at least they have been for me. Haven't a yet tried Enya 4C Engines but I have heard that are generally quite user friendly.     
Phil Spillman


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