Interesting thought. With the OS 4S 91 apparently being replaced by the 110 eventually, what do you think SPA will do when the 91 is no longer available new?

1. Stay with the 91 and find NOS NIB or find used engines
2. Approve the new OS 110 4S and allow piped 61 2S
3. Approve the new OS 110 4S and tell the 61 2S fans to take a hike
4. Reduce the CI to the $340 OS 81 4S.
5. Go back to Mickey’s original plan of 61 2S.

I for one like Mickeys idea of the 61 2S, I've got a ton of the os 61 SF's the 4S are getting real stupid with the prices's. Anybody ever try the Magnum 914S? Pete

the magnum 91 4 stroke works for about 2 flights then breaks.. not made for the pattern world.. seen several of them and also the satio do the same..
I say go 61- 2 stroke or electric

scott
spa 239
Team Castle Creations
www.rcfoamy.com

Why do they have to do anything? The rules simply state "naturally aspirated 4 strokes can be 0.91cuin" don't they? Nothing specifically about the OS brand, right? In that case, the people who choose 4 stroke engines will have to find an alternate engine brand or choice to stay within the rules. Or keep using old engines and rebuilding them. The world moves on without regard for a business decision made by OS.


Mark

I had a Magnum 91-4S in my WM Intruder. It ran pretty well when new. I put a gallon of 15% CP 4 stroke fuel then switched to CP 20% heli, still OK. Then the SPA 30% in my OS hit me and on the second flight the Magnum started to sound funny and on tank #3 the funny noise got loud and the compression got soft. I now have the OS 91but I will not spend 350 on the 81 and see how long it will last. It's original size planes and 2 strokes for me now. Maybe an old OS 70 (not the POS 70FL) in an original size machine but no more big boys.

Peace

Mark O

I've been running a .91 Magnum pretty hard for six or seven years now. It was in an Astro Hog until 2 years ago when it went into a U Can do 3D.
I have been running a pump since I changed it to inverted to go in the U Can Do. It really has been good to me. I've been using Omega 15% in my 2 and 4 strokes for 20 years. I use 15% for the a reliable idle and Omega for the castor content in the 4S. Since it's in the flight box I use it in my few 2S as well.

Ken

I just bought my third OS 91 new from a LHS. I paid $280. A real deal!! I have always wished the SPA would allow at least a 100 Four Stroke so I could use my Saito 100 which is a very powerful and reliable engine. Most of my requests to the SPA have gone the way of the DO DO bird ( extinct)!! I had asked the powers in charge to modify the rules to allow some more recent planes which are available on e...y from time to time. That's why I spend my winters scratch building 1975 and earlier planes from raw plans. I would much prefer to build from a kit that has a proven track record. Blue Jay kits are really nice and I have built several of them. I lust for a fiberglass fuse kit to be readily available for the popular stuff of the past. Don't get me wrong. I really enjoy the SPA events andthe people that compete in the events. They are great folks. I just get frustrated with the lack of availability of approved planes.

Glass fuselage of old birds ? Go to Wing Mfg. Phoenix V is available, and you may find more in the pipeline.

I won't give up my 4 stroke for a two stroke unless the BPA gets more contests. It's a chore to squeeze a four stroke in a fiberglass fuse designed for a two stroke. How about some good wood kits of the Atlas or the like which can be widened during constuction to accomodate a larger engine. I'm in the process of widening and lengthening a Phantom 1 from plans at this time. I like the OS 91 very much for many reasons. I would go back to old style pattern in a second with retracts and a pipe if it were allowed.

A question: I wonder why nobody here is considering [link=http://www.rcvengines.com/rcv91cd.htm]this animal[/link]? Admitted, it's a bit heavier and weaker than the FS-91, but the funflyer guys use it nonetheless.

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Funflyer guys must mean something different in Germany than it does here in the USA.

Fun Fly folks here in the USA use light weight, high powered two-strokes. Perhaps "funflyer guys" in Germany means the equivalent of our sport flyers?


Ed Cregger

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My last OS FS-91 Surpass II cost me about $230 when I used their coupon. Your hobbyshop sounds expensive.

I've returned to using two-stroke engines from the appropriate time period in my SPA models. Sometimes I sneak in a more modern two-stroke and use a tuned muffler. Sometimes.


Ed Cregger

Modern two stroke's.

The next two-stroke I will buy will be a Jett. I want to build an EU-1 A for nostolgic reasons with retracts, pipe, etc. I' m waiting for Carolina Aircraft to send me the fuse and cores. I built three of these in the 80's and loved the beast.

Ed, I was being sarcastic regarding my paying $280 for the OS 91. They list for about $ 300 now. Skip

I would not worry to bad. Someone will find a way for more power, rebuilds, or something like the "animal above". Looks real interesting. You really have to know what you are doing to get a 2 stroke turning out the same power and performance as a comparable 4 stroke, say a 61 2 stroke to a 91 4 stroke. This does not just apply to the engine, but the building and setup of the airframe as well. Not everyone has the knowledge or these skills, so it is so much nicer to just be able to take an engine or ARF/Kit strait out of the box and put it together without the worries of big time modification or hours of re-engineering. A lot of SPAers love competing and are attracted to the SPA because it is affordable compared to other arenas. Also if you've been to many SPA events you would notice quickly that approx. (do not hold me to the exact number) 70 percent of the Novice/Sportsman class are flying ARF's, a (certain one) or ARC, a (certain one) aircraft. This tells the story. I don't believe I have ever seen an ARF compete in expert class, maybe an ARC, maybe. By going to nothing but 61 2 strokes with stock mufflers, there would be a lot of learning to do and the market would have to produce some new (smaller/lighter)(40-50 size) ARF's for the 61 2 strokes.

Which ever way it goes, I will still be a part of the SPA. Its great fun, and a great group of people.

I agree with PatternFlyer 76. I got back in and with the SPA. I did not know anything about this until 18 months ago. I was finishing up a QQ Somenizi 86" Yak. We went up to Ohio for a visit, had dinner with some of my old rc buddies, they were talking about SPA/BPA, and the resurgence of old pattern. I returned home, looked at the P-6 I have carried around for many years, then found out I could buy a couple of ARF's, get flying right away. I did, then unloaded the Yak, joined SPA, and started all over again, where I left off in 1973. I may get out of Novice some day, but happy just to compete.
As far as SPA Expert flyer's using built up planes, I am sure they have been flying those planes since they built them, or took them off the basement, (garage), wall, put modern radios on board, and never missed a step, just fired up, took off, and just like riding a bike, back in the groove. Those guy's are an inspiration to us all.

I am going to fly 2 meter also, getting ready to equip 2 Focus Sports. More contest's that are within 500 miles of here, so another chance to compete again. No desire to be on a Wheaties box, but I can just keep trying to do better. AMA Pattern is another avenue, and I have gotten a lot of help with my questions from the 2 meter guy's, look forward to it.
Vince
Hobe Sound, FL

Be careful Vince

Cees

Is replacing the OS .91 anything more than speculation at this point?

If you can scale a design up 3% or so for a .91 4-stroke (which many have done), they you can certainly scale a design down 3% or so for a .61 2-stroke if a high power loading is what you're after. I doubt too many people would actually do that, but it's obviously within the Duck rule to do so.

David

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Let's not forget that an ARF won the F3A FAI class one year, some years ago.


Ed Cregger

Ed, thanks for the reply, but I meant funflier in the US. Actually, I got aware of RCV only by reading about the Jerry's Big Boy funflier here on RCU. A RCV engine was used there as one alternative. Of course, a funflier needs thrust and not speed and that's why the four-stroke is appropriate. But the RCV91 might even be sort of a Hanno replacement. Has about the same power at 11k rpm and below and weighs less than the Hanno with pipe. Backdraw is all the weight on the model's nose and the carb behind the engine. But it seems to be equivalent to the OS 91. Since it turns a 14x6 prop at 9k rpm (1.2 hp) it might as well turn a 12x11 at 9k. Not too bad.

Much thrust despite not so much power. Wasn't that the reason why the .60 two-strokes are not competitive against the .91 four-stroke, and the actual reason for this discussion?

Ed, ARFs of the composite variety have won every year since. That was the first (and only time) a wood, covered ARF won FAI. Don Szczur won it with a Focus.

-M

Well, many of us like to gripe about the four-stroke .91's not really belonging on an SPA model anyway. The classic pattern models were flown with 10cc two-strokes originally and that's what they should be flown with now - so many of us think.

Lots of folks won't bother with Magnum and Saito .91 engines, although it is my thought that the majority of we SPA enthusiasts aren't going to practice much anyway, when compared to how we practiced when we aspired to be pattern heroes. Meaning that an engine that is less robust than OS might serve us well in our older years. With OS' introduction of the 1.10, some think it likely that OS will discontinue their present .91 size engines, leaving a gap between the new .81 and the new 1.10. Even if they bring out a new .91, it is likely that it will be ridiculously priced. I know I won't be buying any OS four-stroke that costs me more than $250 net, plus delivery. It's just the principle of the thing. I don't endure price gouging with grace.

Personally, if people absolutely had to have a four-stroke engine, I wouldn't be against letting them run a .75. That, even with 30% nitro fuel, would be closer to the power output of a 10cc two-stroke with a high performance muffler (we won't say the resonant word).

I know that you know all of this. I'm just restating some of it so that we're all on the same page.

Moving the permitted four-stroke displacement up to 1.10 would be a bad move. I think we would see a loss in membership as a result. Not that I have room to talk. I keep forgetting to mail the cotton picking check. Sure wish they would accept PayPal. I'm willing to pay the extra 3.9% myself.


Ed Cregger

Aren't you guys going to have eventually move up in a couple of years anyway... unless you want SPA to represent antique aircraft only.
I've got a mid 90's Hydeout, compared to today's F3A planes it's a pensioner.
Even the 80's 1.20 powered somethings are 23 plus years old! Yet don't qualify to take part at a SPA event?
You guy's have rules that keep you firmly planted in the 60's early 70's.
So what's going to be the next step?
Maybe you should start thinking about a New Class... before somebody else does?