mmattockx

All right, all this BPA talk and 8178's many comments about how easy it is to find the OS 61 RE pumper engines on E-b*y has me looking around for a NIB 61 to power my next classic pattern project. Since these engines are discontinued and I wasn't involved in pattern in the early 80's, I have no idea how to read the OS alphabet soup to get what I want. A Hanno Special is a no brainer, but they go for $$$ because everybody seems to think it was the best pattern engine of all time. So, what should I be looking for to get an OS 61, rear exhaust with a backplate pump?

Second, how do these engines stack up against a ST90 in terms of weight (the ST90 is 21oz w/o muffler) and user friendliness? I have 2 of the ST90's and they are a piece of cake to run.


Thanks,
Mark

jlkonn

My Feedback: (1)

I believe the "VF" designation was for the rear exhaust.

Steve25

Hey Mark,

Would you consider to go that way with a Webra ?
I tend to believe these are at least as good, but maybe have a longer life.
I had an FSR ABC, that pealed off, it was used max. one hour, then stand still for 10 years, It was not clean, ok, but when taking it back in service, it ran free. It started, ran well, then started to loose power, while the bearings seemed to have eaten the Chrome.
But I see a lot of oldies still using their OLD webra's, while never notice an old OS.
Now still operating an SF 61, but it never came near the power of the FSR

While I have now a whole bunch of older webra's ( Blackhead and speeds, I will normally have my first rear exit Webra, including it's tuned pipe ).
I bought this while available ( exactly the right one for a Magic ), but this nioce engine will offer me more then 2.2 HP, with very low nitro levels, thus cheap to run .

If You wish, I can watch out for a Webra rear exit for you, new or used ?

s. wallace

My Feedback: (24)

The VF series was very good but from the "small prop lots of revs" era. Had one on a Tipo & loved it, with an 11-7 prop.

The next evolution was the 61RF and RF-P (pumped). Outstanding engines, user friendly and would turn a pretty fair sized prop. I think I ran 12-10 or 12-11 typically with mine. My non-pumped ones ran very well on pipe pressure but I didn't have the fuel tank on the CG either.

I think you would be happy with either VF's or RF's, but I would be wary about buying a used RF-P. I'm not certain but don't believe the pump is available from OS anymore, and there isn't much you can do to service one. If you find one NIB go for it. I ran many, many trouble free hours with several of them.

The Hanno's were based on the RF-P and really were a jewel but like you say, NIB ones are fetching 1 arm and 1 leg.

NM2K

My Feedback: (14)

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To me, and I'm sure everyone has their own opinion, the FSR and VF OS engines were the last of the old OS high revving pattern engines that suit the BPA type of flying. I did manage to collect one of each, but have begun focusing more upon my OS SF engines. Come to find out, the real high rpm engines jangle the nerves a bit more than I care to admit.

I envied the fellows that I saw flying the RF and Hanno engines at our field many years ago. It was hard to believe that such quiet engines could produce such fantastic power. Hence my leaning toward the less expensive, ringed OS.61SF. I don't even need a pipe to manhandle my old Kaos models.

I owned and flew a Webra .61 Speed (ringed) in the early Eighties. Easily as powerful as the OS .61's of the era and just so "ho-hum" to operate without hassles. I wouldn't mind finding a couple of those these days.


Ed Cregger

mmattockx

Thanks for the info, everyone. I am now a little wiser and can scan the classifieds and auctions with an idea of what I want.

I like the sound of the RF-P for what I want, with a quiet pipe and high pitch prop, it will haul and not offend the neighbors at the same time. All good stuff.

Does anyone know if the VF/RF series are the same size as the current 60/90 size engines? If they are, then there seems little reason not run the 90's if you wanted a side exhaust engine.


Thanks,
Mark

s. wallace

My Feedback: (24)

The OS 61 SF/RF series have the same mounting "footprint" as the 61 & 91 FX. I replaced a 61SF with a 91FX, other than the 91 being a bit taller was no issue. The FX series has that rear-mount needle which I don't care for, especially when trying to nest it into a sleek nose of a pattern model. Looks like OS is going back to the needle on the carb (angled back), at least they did with the new 55AX.

I don't know if FSR series are physically the same size as the others, has been many years since I have had one.

Steve25

FSR's are not smaller, still they are lighter then an SF,
After replacing the defect FSR with an SF, I had to make major corrections to the balancing of the airplane.
Webra Speed 61 485gr
OS 61SF 550gr+, exhaust 150gr
OS 61 FSR 490gr, exhaust 120gr
The housing of the SF also has a marking stating 'VF'.
OS 61FX has a weight of 550gr, while
OS 90FX 560gr.
To talk about the old Webra Blackheads, these engines are in the .40 class weight, and if I remember well, they have another (smaller ) footprint. While their power doesn't come near the old fsr/.... engines, they still can take 11 x 7, or a dealer, which is flying for over 40 years, said they would take a 12 or 13 /7 as well.
Didn't test that yet, as my stuff is packed [&o]