Stunt Engines and the ST 51

As an interesting hypothetical... I was wondering if the current PA and Ro-jett piped engines were not avaialable, what would the current top Stunt pilots use as a powerplant. ST 60, Modusa, OS, Merco, ST 46, ST 51 or other?
The reason I wonder is that I have run my Magnum with an ST 51 now for about 75 flights. And for the life of me I cant imagine a better stunt engine. I use a bolly 3 blade, 11.5 in 5 pitch prop.
The things going for the ST 51 are as I see it:
Readily available
Cheap $100
Gobs of power. I can fly the entire pattern in 4 cycle. This engine has more power that anyone could really want. Cenrtainly more than an ST 46 and enough for 700 square, 60+ oz models. Why would anyone need an ST 60?
Smooth Stunt runs. The "break" I get is from a rich 4 cycle to a lean 4 cycle, with just a hint of 2 cycle where its needed. Really smooth and even breaks. Even at this it pulls so hard my arm get tired.
Light for the power output. about 11 oz.
Simple- bolt on a tongue muffler and fly
Starts easily- usually on the first flip
Consistent- I havent touched the needle in over 20 flights and it runs the same- perfect.
Given this I am really surprised that I dont see more use of the ST 51. I also use and have run an OS LA 46, with MAC muffler and with a tongue muffler. Its a nice setup but doesnt even come close to the power, consistency, smooth stunt runs and ease of use as the ST 51 does in my experience. So why arent these motors more commonly used?
And back to my original question: If the current piped motors werent available, would these be considered or used by the top tier pilots?
Just wondering...Brian

>As an interesting hypothetical... I was wondering if the
>current PA and Ro-jett piped engines were not avaialable,
>what would the current top Stunt pilots use as a powerplant.
>ST 60, Modusa, OS, Merco, ST 46, ST 51 or other?

40/46VF.

>>As an interesting hypothetical... I was wondering if the
>>current PA and Ro-jett piped engines were not avaialable,
>>what would the current top Stunt pilots use as a powerplant.
>>ST 60, Modusa, OS, Merco, ST 46, ST 51 or other?
>
>40/46VF.
>
> Brett

Saito 72.
Saito 56.
OS Max 52 FS.
OS Max 70 FS Ultimate 2.
YS 63.

>Gobs of power. I can fly the entire pattern in 4 cycle. This engine has more power that anyone could really want.

Sorry to say but the ST51 is not even in the same league with the PA engines. I've flown them both and the PA 51,61 &65 are stronger and lighter. Also the PA is a longer lasting & better built motor, available in rear or side exhaust. Bottom line is you get what you pay for.

ST51= 11.6oz
PA61&65 = 11.4

>Sorry to say but the ST51 is not even in the same league
>with the PA engines. I've flown them both and the PA 51,61
>&65 are stronger and lighter. Also the PA is a longer
>lasting & better built motor, available in rear or side
>exhaust. Bottom line is you get what you pay for.
>
>ST51= 11.6oz
>PA61&65 = 11.4

Larry,
I wasnt trying to directly compare the 51 with the PA engines. Its just that the 51 doesnt seem to be widely used as opposed to the ST 46, OS 46 and others. BTW the ST 51 weighs in at 10.9 oz on my Tom morris digital scale.

>Larry,
>I wasnt trying to directly compare the 51 with the PA
>engines. Its just that the 51 doesnt seem to be widely used
>as opposed to the ST 46, OS 46 and others. BTW the ST 51
>weighs in at 10.9 oz on my Tom morris digital scale.

Sorry miss-understood that part of your post. I need to get away from the Forums and back to building engines and airplanes.
The one I have here tips my scale at 11.6 and the Aero 61 at 11.4. My digital scale is getting up there in years and I just can't bring my self to putting that much weight on my good scale for balancing engines. That must mean all my planes are lighter then I thought. Don't get me wrong I think the ST 51 is a great engine. As for all the power one would need, I thought the OS VF46 was all the power I needed until I dropped a PA in my plane. For the price it's cheep no doubt. Made in Mexico now I think, even if it does say made in Italy.

If the PA or RoJett were extinct I would to go to the OS VF.

>If the PA or RoJett were extinct I would to go to the OS VF.
>
>Larry

Which is already extinct!

There's nothing wrong with the ST-51, or the OS-40vf, or and or.etc
The question is What Plane is the best for the ST-51. SV-11 comes to mind.

Scott(in that wing area)Riese

Hi Scott, et.al.

The SV 11 is a GREAT match for the ST 51 (which is made in China now, Larry ). I made my biggest "jumps", contest wise, with that set up. Mine was 64 oz. Any 'smaller, light' 60 size ship will do fine with it. It's "killer" on the USA-1.

As to it's popularity, it's release coincided with the developement of "pipes". Windy, and some others, tested the 51 on pipe.
As is the norm, when the pipes caught on with the "Top Dawgs", that became the "hot" set up and the 51 just never gained a following with the top fliers. So as it wasn't being flown to top placings by experts, it didn't gain a reputation with a lot of other fliers. It is a very good power plant for stunt.

I do think, however, that it would be tested on a 70+ oz. Patternmaster! LOL!!

Bill <><

Thanks Bill. Now that the engine is available it can do nothing but good for C/L. For someone not looking to spend $400.00 to $550.00 on a top notch set up it's great and can power a very competitive plane and have three back-ups for the same money.

>There's nothing wrong with the ST-51, or the OS-40vf, or and
>or.etc
>The question is What Plane is the best for the ST-51. SV-11
>comes to mind.
>
>Scott(in that wing area)Riese

Scott,
I think Magnum Ha Ha!!!

Mikey,
I did like my Magnum with the St 51. It has had a rather poor "iron on" finish I did removed, and is awaiting a new paint job! It does fly real good in that configuration. Actually I have seen a few Magnums powered by St 51's fly real good.
Bill <><

>>There's nothing wrong with the ST-51, or the OS-40vf, or and
>>or.etc
>>The question is What Plane is the best for the ST-51. SV-11
>>comes to mind.
>>
>>Scott(in that wing area)Riese
>
>Scott,
>I think Magnum Ha Ha!!!

OOOPPPSSS

I forgot we have real desingers on this forum.

Scott(sorry Mike)Riese

Brian....methinks that most of the tuna pipe gurus would admit that a HUGE contributor to the success of pipe power is a flat prop....in the 4" range. Advantages are many, but a constant speed and controling "wind up" top the list.

See Ya

Brian,

Part of the problem here is you are making a classic mistake in a straight-line projection of what all US fliers are using based upon what is being flown in your area.

I have owned a couple ST 51s, both quite good. In particular my first Impact had a really nice ST 51--CL version--in it and after converting model to a Saito 56 I spent the first few flying sessions questioning the wisdom of my decision.

For what it's worth, when flying the ST 51s I was never tempted to buy an ST 60 no matter who had fiddled with it.

Gordan Delaney has a superb ST 51 in his Classic Stunt model and he seems able to fly at the highest levels pretty effectively with it.

You're not the only one.

>As an interesting hypothetical... I was wondering if the
>current PA and Ro-jett piped engines were not available,
>what would the current top Stunt pilots use as a powerplant.
>Just wondering...Brian

I am not yet a "top stunt pilot" but:
Saito 72
Saito 56
O.S. Max 52 FS
O.S. Max 50sx modified
Irvine .53 modified
Stalker .61 SE

Brian,
Well heck I think I am going to put in my two cents worth and I may get some flak but that’s OK.

How much better can a pipe set up be, than the St.51? Well there is a big difference when you have acquired the skills and knowledge of how to properly run a pipe set up. Peabody was close with his remarks about wind up being one of the major considerations but there is more to it than that. The constant speed of the model through all the maneuvers helps keep your timing during each maneuver more consistent. The pipe regulates the power of the engine with slight boosts of power on the ascending vertical portions and reduces the power on descending vertical portions of the pattern. The same is true for a simple loop or figure eight power on & off throughout the pattern.

In perfect stunt air 5 to 7 mph the ST's and Stalker's can hold there own but when the winds pick up, (or dead calm) the advantage goes to the pipe set up hands down.

The trick with the pipe setup is to knowing when and how the make slight changes to the prop and pipe length to optimize the performance gain from the pipe set up. If you are not willing to make these small changes and do a little experimenting to learn just how you airplane is affected with these small changes, then maybe you would be better off with the 4-2-4 style of engines

Here is a supre tiger G51 that a friend bought from an RC flyer for 15 dollars. Note the rear intake. I'm in the process of trimming the engine out for this profile magnum. The venturi is to small at this point. The next bit of R&D will be to open up the venturi and get a little more speed out of the engine.I think when everything is in trim this will be a nice flyer.

Mike