Old OS 15
06-07-2008, 08:26 PM
#27
RE: Old OS 15
Well... I'm close to hijacking another thread... but since I'm a little board and since there are few engines around here and I have a camera in front of me....
The first pictures are of the engine that came before the engine pictured in the thread starter. I bought this engine when I was about 14 and never used it. It is refereed to as an OS "Steel Fin" for obvious reasons. It came from a time before we discovered that a sleeve was a good thing. Steel fins (cylineder) with an iron piston and pre-synthetic oil... this was the time castor oil made its name.
The second set of pictures is of an HP .61. It is significant not because it has a baffle, but because it doesn't! It was the first production Schnurle (loop scavenged
)engine. Up until this engine, all model engines were cross scavenged engines like the engine pictured in post #1. This engine happens to be a very rare 2 ring RC version and included a muffler. Also notice the exhaust is on the "wrong" side. The carb is a plumbers nightmare. While I have the engine in front of me and the factory instructions, I have no idea how it works.
The last engine is an Super Tigre .71. I don't know why I added it. It was in front of me. I like it because it says "Made in Italy". Of course they are now made in China. Of these three engines, one has a 4 bolt head, one has a 6 bolt head and the ST has an 8 bolt. Over the years I've found nothing to suggest one is better than the other.
Bill
The first pictures are of the engine that came before the engine pictured in the thread starter. I bought this engine when I was about 14 and never used it. It is refereed to as an OS "Steel Fin" for obvious reasons. It came from a time before we discovered that a sleeve was a good thing. Steel fins (cylineder) with an iron piston and pre-synthetic oil... this was the time castor oil made its name.
The second set of pictures is of an HP .61. It is significant not because it has a baffle, but because it doesn't! It was the first production Schnurle (loop scavenged
)engine. Up until this engine, all model engines were cross scavenged engines like the engine pictured in post #1. This engine happens to be a very rare 2 ring RC version and included a muffler. Also notice the exhaust is on the "wrong" side. The carb is a plumbers nightmare. While I have the engine in front of me and the factory instructions, I have no idea how it works.The last engine is an Super Tigre .71. I don't know why I added it. It was in front of me. I like it because it says "Made in Italy". Of course they are now made in China. Of these three engines, one has a 4 bolt head, one has a 6 bolt head and the ST has an 8 bolt. Over the years I've found nothing to suggest one is better than the other.
Bill
06-07-2008, 09:20 PM
#29
RE: Old OS 15
Makes me feel old when someone says they've never seen a baffle-piston engine before.
Some of my best friends have baffled-pistons.
When the OS Max-1 .15 came out in 1958 it quickly became the FAI World Power champion.
By 1964 it was the Max-III RC was main engine used to establish the popular Quarter-Midget RC racers.
They are very compact and willing runners. Early versions had steel cylinders and the last of the breed had a unit construction case with drop-in liner.
I would not hesitate to use a Max .15 today.
Some of my best friends have baffled-pistons.
When the OS Max-1 .15 came out in 1958 it quickly became the FAI World Power champion.
By 1964 it was the Max-III RC was main engine used to establish the popular Quarter-Midget RC racers.
They are very compact and willing runners. Early versions had steel cylinders and the last of the breed had a unit construction case with drop-in liner.
I would not hesitate to use a Max .15 today.
]
06-07-2008, 10:34 PM
#32
RE: Old OS 15
Ahhh the OS pet. (Notice it's not an OS Max.) I love this engine for a lot of different reasons. The fact that you could get it with a muffler is out of this world for the era it was produced in. I love the fact you could get it in an "RC" version but in the end it was just an air retractor stuffed in a CL engine. This is a .099 in an era when there were 1/2A, .20's, .40's and .60's. Like the OS that started this thread it began as a "Steel Fin" but changed over its production life.
I miss the days when engines made substantial improvements with each generation.
Bill
I miss the days when engines made substantial improvements with each generation.
Bill
06-07-2008, 10:51 PM
#33
RE: Old OS 15
Bill, I guess you know that there are two different #701 mufflers. You appear to have both versions.
The #701 I have fits the 1971 Pet III with four backplate bolts. Unfortunately, the exhaust port on my 1959 Pet II is too large for it. I'll have to keep my eyes out for the earlier #701 version that fits the Pet II.
David
The #701 I have fits the 1971 Pet III with four backplate bolts. Unfortunately, the exhaust port on my 1959 Pet II is too large for it. I'll have to keep my eyes out for the earlier #701 version that fits the Pet II.
David
06-07-2008, 11:12 PM
#35
RE: Old OS 15
It runs great! The fuel draw is excellent. Since there is no idle stop I had to be careful closing the throttle. But, with a servo it would be easy to set the barrel travel end-points. It throttles about the same as my Fox .15X. It works better than the ring throttle on my Cox Medallion .15, but not as good as the #21 carb on my Max .15.
I have a thread on it here where I describe how it runs:
http://www.rcuniverse.com/forum/m_7586149/tm.htm
David
PS: do you have an extra Pet II #701 muffler? I'll trade you my Pet III #701 for it.
I have a thread on it here where I describe how it runs:
http://www.rcuniverse.com/forum/m_7586149/tm.htm
David
PS: do you have an extra Pet II #701 muffler? I'll trade you my Pet III #701 for it.
06-07-2008, 11:21 PM
#36
RE: Old OS 15
The #701 I have fits the 1971 Pet III with four backplate bolts. Unfortunately, the exhaust port on my 1959 Pet II is too large for it.
It seems odd to me that the exhaust port got smaller on later versions of the PET 99. In this time frame engine manufactures seem to gravitate to larger exhaust ports for improved performance... This was not the case with the PET 099. It actually got smaller with time..
Bill
06-30-2010, 11:37 PM
#39
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RE: Old OS 15
I have one of the first manufactured HP 61 with a 4 bolt head I am getting ready to list on e-bay; any one here tell me what this vintage engine is worth?
