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Author Topic: OS 26 FS on a pat Johnston ringmaster +P  (Read 17311 times)

Offline Dane Martin

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OS 26 FS on a pat Johnston ringmaster +P
« on: February 26, 2015, 08:12:20 AM »
My latest project is an RM+P from Pat Johnston. The plane is not finished, but seriously close. I'm using the OS 26 four stroker. When it's all done, I'll weigh it ready to fly.
 I wanted the family involved (or was it the other way around? Lol ) so the shapes are just cut from monokote, everyone signed the plane in Sharpie then i used clear monokote to seal everything up. The wing is all in clear, and we'll add some graphics to that also

Offline Bill Little

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Re: OS 26 FS on a pat Johnston ringmaster +P
« Reply #1 on: February 26, 2015, 09:32:38 AM »
Looks good Dane, nice idea!  At least it won't be tail heavy with the FS!

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Online Brett Buck

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Re: OS 26 FS on a pat Johnston ringmaster +P
« Reply #2 on: February 26, 2015, 12:34:43 PM »
My latest project is an RM+P from Pat Johnston. The plane is not finished, but seriously close. I'm using the OS 26 four stroker. When it's all done, I'll weigh it ready to fly.

  I have seen a number of them with 26 Surpass' and it works out pretty well.  You can tolerate a very-far-forward CG with the Ringmaster, but you still might have to add some tail weight, particularly with the very light finish. Read the other Ringmaster setup threads (of which there are many) for the other things to watch out for - particularly the control rates, and the tendency of the wings to break off.

    Brett


Offline Dane Martin

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Re: OS 26 FS on a pat Johnston ringmaster +P
« Reply #3 on: February 26, 2015, 06:32:44 PM »
You guys are totally right. I really don't like the idea of adding lead, but there's no way around it in this case. But, the plane came out exceptionally light. Pat Johnston hand selected all the wood for me. So it's still gonna be light even with some tail weight.

Offline Dane Martin

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Re: OS 26 FS on a pat Johnston ringmaster +P
« Reply #4 on: March 01, 2015, 07:47:36 PM »
Getting close. Playing with the kid, so not working to hard on the plane. The way out came out for balance, it's flyable. I like my CG back a little more, so will definitely add some tail weight.

What prop would guys use on an OS 26 fs ? 9x5? Just a guess....

Offline Bob Reeves

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Re: OS 26 FS on a pat Johnston ringmaster +P
« Reply #5 on: March 02, 2015, 02:13:47 AM »
I would fly it before adding any tail weight to see how it actually does. It's a known phenomenon that 4 stroke powered airplanes can have the CG much farther forward than it would be with a two stroke and still turn. The Saito 40 powered Twister I flew from Intermediate to the middle of Advanced had the CG at the wing's leading edge.

Offline Robert Zambelli

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Re: OS 26 FS on a pat Johnston ringmaster +P
« Reply #6 on: March 02, 2015, 07:09:24 AM »
Hi, Dane - first off, go with Bob Reeves advice. He knows more about 4-stroke engines than anyone else on this site.

Regarding the OS 26 Surpass. I have around 500 flights with these engines on 9 or 10 different aircraft. One plane is powered by three of them.

Among the planes, a Flight Streak, Nobler, Colibri (three engines), the Sterling Mustang (fixed flaps) and many more.

The 26 on the Sterling Mustang was absolutely the best combination. It not only brought home many OTS trophies but also quite a few in Advanced AMA Stunt, beating planes like the Cardinal and Oriental.

I consider the Surpass 26 the best of the entire Surpass line and I've owned and flown most of them.

For the 26, the best prop I've used in all applications is the Master Airscrew 9-6 plastic prop.

For fuel, Powermaster 20/20 and Brodak 10/23-50/50 both work quite well.

As they are prone to leak air at the carburetor drum valve, you must seal it to get consistent runs - see my article in CL World or I will send you a copy.

To really eliminate carb issues, you can make a venturi like I did for my engines - see the photo.

Best of luck, Bob Z.

Offline Dane Martin

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Re: OS 26 FS on a pat Johnston ringmaster +P
« Reply #7 on: March 02, 2015, 07:27:58 AM »
Mr Reeves, that's good to know and I'll try it. It's about 1/2 inch back now. On an ots legal ringmaster, i like it back over an inch. But I've also never had a four stroke ringmaster.

Bob Z, thanks for the advice. I didn't make a venturi on my os fs 40's, but i did something similar to what Bob Reeves explained on the saito carbs. I love the OS fs engines. I have two 26's but this is my first attempt with one.
Power master 20/20 it's my favorite fuel, so that's good to hear. Master airscrew props are easy to get down the street. Sounds like fun!!!

Offline Andrew Tinsley

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Re: OS 26 FS on a pat Johnston ringmaster +P
« Reply #8 on: March 03, 2015, 01:21:32 PM »
Hello Bob,
I am intrigued to learn that 4 stroke models can have a much further forward CG than when flown with a 2 stroke engine. I am not doubting your statement, have you any idea why this is. I cant think of a good reason, but there must be one!

Regards,

Andrew.
BMFA Number 64862

Offline Bob Reeves

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Re: OS 26 FS on a pat Johnston ringmaster +P
« Reply #9 on: March 03, 2015, 02:16:57 PM »
The CG phenomenon was discovered way back in the early days when many were experimenting with 4 strokes. Several simply replaced a two stroke with a heavier 4 stroke then discovered even with the more forward cg the airplane still turned as well as it did with the two stroke. Several with allot more book learnin than me tried to explain the why, but not sure anyone came up with anything but conjecture.

Offline Dane Martin

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Re: OS 26 FS on a pat Johnston ringmaster +P
« Reply #10 on: March 03, 2015, 09:02:30 PM »
Here it is finished. I know the zinger props are not the best, but i just liked the look. I did but some master airscrew 9x6 props also. I will experiment and if i can't tell enough difference, I'll stick with wood. It matches the plane well.

Offline Bob Reeves

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Re: OS 26 FS on a pat Johnston ringmaster +P
« Reply #11 on: March 04, 2015, 02:24:58 AM »
Bob Z is the OS guy, he has allot more experience running OS engines than I do so take this with the understanding that I am coming from a Saito view point.

If you like wood props might check out the RSM wood 9-6 and see if you can find someone that has a stash of the props George Aldrich use to sell. A wanted add in the classified section may produce a few of the Aldrich props. RSM claims it's props are more efficient than the Aldrich prop but on a 4 stroke I'm not so sure that is a good thing. I know Saito's like to be loaded and the most efficient prop isn't always the best choice. Get you hands on a couple each and compare all four props (RSM, Aldrich, Zinger and MA) to see which one you feel the engine is happy with.


Offline Martin Quartim

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Re: OS 26 FS on a pat Johnston ringmaster +P
« Reply #12 on: March 04, 2015, 06:07:24 PM »
 Ringmaster P+ with a 4S that is sooo cool!  I wish I had the time to make one.

Martin
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Offline Dane Martin

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Re: OS 26 FS on a pat Johnston ringmaster +P
« Reply #13 on: March 06, 2015, 11:46:39 AM »
Thanks Martin! It's definitely a sweet airplane. I'll bee flying it Sunday. I expect it to be amazing

Offline Robert Zambelli

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Re: OS 26 FS on a pat Johnston ringmaster +P
« Reply #14 on: March 06, 2015, 02:58:08 PM »
Hi, Dane - the plane looks great.

I have one suggestion: the inboard mounted tank may give you some problems.
It may tend to cause the engine to run richer as speed increases.

You may want to try a Hayes 3 ounce clunk tank. Excellent quality, available from Tower Hobbies (part # LXK826).
It should fit between the engine and lead edge.

By the way, the tank you have on the plane now looks pretty big - how long do you like to fly?  LL~  LL~
I had a Surpass 26 on my Cardinette and it ran the entire stunt pattern on 2 ounces.

In any case, do try the setup that you have now. If it works, great.
If not try another tank.

Bob Z.

Offline Dane Martin

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Re: OS 26 FS on a pat Johnston ringmaster +P
« Reply #15 on: March 06, 2015, 04:08:26 PM »
The tank is way too big... It's a four ounce. I strapped that on because that's the size i always use on my ringmasters. Bad habit, all my other ones are two stroke.

So far for me, the inboard tank is the only way I've been able to get consistent runs. I've tried the uniflow and suction setups, but can't figure it out. So all of my profiles have the tank inboard on muffler pressure. If i can make it to the hobby shop, i would like to get a smaller tank!

Offline Martin Quartim

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Re: OS 26 FS on a pat Johnston ringmaster +P
« Reply #16 on: March 07, 2015, 05:47:18 AM »

I also have experienced that in board tank works better on profile.

How much fuel does it burn?

Martin
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Offline Dane Martin

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Re: OS 26 FS on a pat Johnston ringmaster +P
« Reply #17 on: March 08, 2015, 02:51:03 PM »
Ok, so the maiden flight was today. And WOWEE!!!! What a sweet flying airplane. Lap times were about 5.4 or 5.5  .
Two ounces is plenty to do the pattern. I broke the engine in on the plane at home a few days ago. Then today, i ran it a little rich and flew 3 oz oz. Went way over for the pattern, but that's great. It was a good maiden flight.

Ps. I'm not that sold on the zinger 9x6 wood prop. Looks pretty, but that's about it! Lol. Thank you guys. I believe i have some Aldrich props coming to test. More testing to come!!!!

Offline Martin Quartim

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Re: OS 26 FS on a pat Johnston ringmaster +P
« Reply #18 on: March 10, 2015, 09:51:04 PM »
Ok, so the maiden flight was today. And WOWEE!!!! What a sweet flying airplane. Lap times were about 5.4 or 5.5  .
Two ounces is plenty to do the pattern. I broke the engine in on the plane at home a few days ago. Then today, i ran it a little rich and flew 3 oz oz. Went way over for the pattern, but that's great. It was a good maiden flight.

Ps. I'm not that sold on the zinger 9x6 wood prop. Looks pretty, but that's about it! Lol. Thank you guys. I believe i have some Aldrich props coming to test. More testing to come!!!!

OS 4S are very fuel efficient and I like that!

Martin
Old Enya's never die, they just run stronger!

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Offline bruce finley

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Re: OS 26 FS on a pat Johnston ringmaster +P
« Reply #19 on: March 11, 2015, 05:31:36 PM »
We need video!!! ;D ;D

Offline Dane Martin

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Re: OS 26 FS on a pat Johnston ringmaster +P
« Reply #20 on: March 13, 2015, 10:15:06 AM »
We need video!!! ;D ;D


Still working on it. We misplaced the cord to the camera that was used. So this weekend, we'll try it with a different camera. It will have to be in between speed runs with the sport jet though.... ;)

Offline Gerald Schamp

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Re: OS 26 FS on a pat Johnston ringmaster +P
« Reply #21 on: March 21, 2015, 02:49:00 PM »
Hi Folks, I'm the one who originally put the OS .26 on Pat Johnston's Ringmaster. I got the plane from him and it had an FP .25 on it. It flew okay, but I wanted to try the little OS .26 four stroke. I got the manifold reworked by Bob Zambelli and it worked flawlessly from day one. I used a Perfect 2 ounce fuel tank, changed the fill tube out so it pointed forward, used muffler pressure, 10 X 6 Top Flite wide blade prop and flew on 62 foot lines. It was very nose heavy, but after I learned how to do a good landing when the engine stopped, the nose heavy condition did not hurt anything. I tried adding tail weight at one time, but plane did not fly as well. It weighed 27 ounces with the .26, 25 ounces with the FP .25.

Pat built the plane and it was very light, monokote on the wing an tail, Rustoleum on the fuse. The only realy change I did to the thing along the way was to put a 1/32" wire between the landing gear legs, they were 3/32" and a bit springy. But, the secret to getting a good landing was to be close to the ground when the engine stopped and get it on the ground ASAP, no down elevator, just hold neutral. John Thompson has the plane now and is having as much fun with it as I did.

I started out running SIG fuel with Castor oil in it, as time went on the engine started running ratty, at this time I noticed that everyone was using Power Master 4 stroke fuel, so I changed to it. The fuel cleaned the valves off and it started running fine again. Thanks to Bob Reeves and Bob Zambelli for making 4 stroke flying fun. Wish they still made the OS .26 four stroke they are so good. 

Offline Dane Martin

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Re: OS 26 FS on a pat Johnston ringmaster +P
« Reply #22 on: March 21, 2015, 08:11:14 PM »
Hi Gerald!
Pat told me all about that story. I told him coincidentally, i have two os26fs engines laying around. That plane was the inspiration for this project. What a sweet flying set up.

Offline Bob Reeves

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Re: OS 26 FS on a pat Johnston ringmaster +P
« Reply #23 on: March 22, 2015, 08:57:21 AM »
BTW: De Hill has been bringing his OS 26 powered Ringmaster out lately and that is one sweet running four stroke. Believe he is running an APC 9-6 and even using a hard tank which I have never been able to make work on a Saito no matter how I plumbed it. Not sure what fuel he is running but whatever it is, it is sure working on that little OS.

Offline Gerald Schamp

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Re: OS 26 FS on a pat Johnston ringmaster +P
« Reply #24 on: March 24, 2015, 12:39:43 PM »
Dane, if you don't have a home for that extra OS .26, it could live at my house. I'd like to have another Ringmaster like that, it was the most fun to fly. Bob Zambelli got me started on the .26 as I he was flying one on a Sterling Mustang, I don't remember for sure, be I don't think it had flaps either. It was on one of Windy's old videos.

Offline Douglas Ames

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Re: OS 26 FS on a pat Johnston ringmaster +P
« Reply #25 on: March 29, 2015, 08:02:38 PM »
IIRC De Hill's is an S-1 with some tailweight added. Flys great.
Yours should be even better with that nice airfoil!
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Offline Dane Martin

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Re: OS 26 FS on a pat Johnston ringmaster +P
« Reply #26 on: March 29, 2015, 10:01:25 PM »
Funny you mention this Doug!
I flew it again today. I tried a couple things Bob Z told me on the phone, and it ended up just needing no muffler and run on suction. After that WOW! that engine woke up. it was as powerful on 60' lines as my S1 with a 25LA on 52' lines!
 And for the corners... I was flying the pattern, but went around several times to practise the squares. It hit the corners so hard, my first square turned into a triangle! Took 4 squares before i got a pretty one. Gotta get used to this level of crisp action! It feels great

Online Brett Buck

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Re: OS 26 FS on a pat Johnston ringmaster +P
« Reply #27 on: March 30, 2015, 10:02:40 AM »
Funny you mention this Doug!
I flew it again today. I tried a couple things Bob Z told me on the phone, and it ended up just needing no muffler and run on suction. After that WOW! that engine woke up. it was as powerful on 60' lines as my S1 with a 25LA on 52' lines!


'!!!!   Glad your 26 works, but -  52 foot lines with a 25LA?!!! Either you found a 2" pitch prop, or you didn't crank it up enough. The biggest issue most people have it that they think it is way too fast. It should pull any suitable airplane at 4.5 second laps on 60' lines. On a Ringmaster, running correctly with a 9-4, it will be under 4 seconds on 60' line. I know, we tested it. That's why the 25 is far too big for a Ringmaster.

    The second most common issue I found when troubleshooting various people's "small engine" installations (second after "we improved it") was that many people are unwilling to set the needle correctly. They have this association of "two-stroke" = "burn up". Look how RC guys run them - tune for maximum squeal. They run them flight after flight that way and that is how they are intended to run. 

  If you try to run it in a 4-stroke, then, yes, you won't be happy with the power.

    I recommend starting by *peaking the engine out* - that is, running the needle in until it goes over the top, then back off to find the peak RPM. Then richen it up until it shows the first distinct drop in power - anywhere from 2-5 clicks on the stock needle. I guarantee it won't be too slow and I guarantee you won't want to fly it on 52' lines.

    Brett

Offline Dane Martin

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Re: OS 26 FS on a pat Johnston ringmaster +P
« Reply #28 on: March 30, 2015, 11:54:28 AM »
We run 52's when we're doing our little club races, but you are correct. A bit of an exaggeration for the four stroke fans. But really, the performance is amazing From this little 4 stroke. I don't want to say a direct comparison, because this is the only +p air foil i have.


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