Ringmaster conundrum

[Larry Renger]

OK, there is a very light Ringmaster with an FP 20 on it that is too fast on 60’ lines. Turns out there is about 1/2 oz of tailweight lurking in the rear. So, do I constrict the venturi on the engine oe substitute a .15? The choices are an OS steel fin, a .15 FP or a Brodak .15? The plane has a 2oz tank and is a bit shy of duration to do the OT pattren.

[Larry Fernandez]

OK, there is a very light Ringmaster with an FP 20 on it that is too fast on 60’ lines. Turns out there is about 1/2 oz of tailweight lurking in the rear. So, do I constrict the venturi on the engine oe substitute a .15? The choices are an OS steel fin, a .15 FP or a Brodak .15? The plane has a 2oz tank and is a bit shy of duration to do the OT pattren.

The best flying Ringmaster I have flown was a very light 19 1/2  ounces with an FP .15
Uncle Jimby won Old Time at the Golden State Championships with it.(I hate it when someone beats me with my plane).
I flew it  with .012 lines at 59 feet. The FP .15 was very happy with an APC 8-4 prop.
Give the .15 chance, I think you’ll be happy with it.

By the way, your still a smart-ass

Larry, Buttafucco Stunt Team

[Gary Dowler]

I second Larrys opinion. The 20fp is a bit much on a light Ringmaster , so get yourself a 15FP. A 8-4 APC and a 2 oz tank and you are set.

Gary

[Brett Buck]

OK, there is a very light Ringmaster with an FP 20 on it that is too fast on 60’ lines. Turns out there is about 1/2 oz of tailweight lurking in the rear. So, do I constrict the venturi on the engine oe substitute a .15? The choices are an OS steel fin, a .15 FP or a Brodak .15? The plane has a 2oz tank and is a bit shy of duration to do the OT pattren.

    A15FP is about right for a Ringmaster, even a relatively heavy one. David and I both test-flew one that way, that's what spun me up to put the 20FP on the Skyray. Try a 9-5 cut down to about 8.5, or an 8-4 APC. The OS or Brodak - forget it, no way in hades, they are in a completely different time zone from the FP.

   I think that some people are just not getting the idea here - the notion that a OS 15 Steel-fin could possibly be subbed in where a 15FP goes, or be a slight reduction in power from a 20FP, completely misunderstands the magnitude of the power difference. And the 15FP is not even that strong, by 15 standards. It's a mild sport motor from the 90's - but it's a different time zone from the old crock baffle-piston 15s.

     Same with the Veco 19BB and the 20 or 25FP - yes, the 19BB can put out nearly the same power in our application, but only by thrashing it within an inch of its life, requiring cylinder baffles, etc, just to keep alive for a while. The 20FP is a bit stronger the way we run it - but can do it much more reliably, and with much better run quality. It runs about the same speed in the air as the Veco (maybe 13,000 rpm) - but if you wanted you could get another 3000 RPM out of it. It's just coasting when run as recommended for stunt, and even then, is way too much for a Ringmaster, it will run that way forever if you want.

   Running a 15FP, stock, or a 20FP with a sleeved-down or smaller venturi (please DO NOT drill it out for an ST spraybar, which will sort of accomplish the same purpose, but permanently damages the crankcase, making it irreversible), is the way to solve the issue. An alternate solution is to take the 9-4 APC and depitch it to about 3.6", or until the speed becomes tolerable. Or, if you are really ambitious, get a 9.5-4.5 Bolly and depitch that.

     Brett
     

[GERALD WIMMER]

Hello

For those of us that build heavy or like to be different here's my answer an Enya 45 model 6001 . My stock Ringmaster flies well enough for me especially in high wind (normal NZ weather) on 64 ft lines. This model has placed well at contests even if it turns a little 'wide' compared to the 20/25 powered Ringmasters models I have flown against. Like a Fox 35 the old Enya 45 is no powerhouse but runs well with a nice sound to it. I de-tuned it too much initially and had to open it up as it was too slow and we fly a simple ' rounds' pattern with no squares, here in New Zealand for Classic Stunt  .
Back in the early 1980's I built my Super Ringmaster with a Enya 45 'baldie' in it and won and placed well in a number of classic stunt events till the silk covering perished but it still decorates the modelling room wall now.

A diesel engine that would probably work well in a Ringmaster, Shoestring or Flite Streak like a PAW 19 TBR diesel (with stock muffler) as they are light and powerful and sound nice with those low revs but the black exhaust goo may put some off! From experience I would say you need the smooth running ball-raced versions not the cheap bushed versions to get the best out of a diesel on a stunt model.

Regards Gerald

[Jim Hoffman]

Larry - If all is working well, try less prop pitch to slow it down

[paw080]

OK, there is a very light Ringmaster with an FP 20 on it that is too fast on 60’ lines. Turns out there is about 1/2 oz of tailweight lurking in the rear. So, do I constrict the venturi on the engine oe substitute a .15? The choices are an OS steel fin, a .15 FP or a Brodak .15? The plane has a 2oz tank and is a bit shy of duration to do the OT pattren.

Hi Larry, what size(diameter and pitch) prop is the FP20 flying with?   If the Ringmaster is to retain the
Fp20 for power, the model is going to need a larger fuel capacity tank.  Can the engine turn an inch
bigger diameter prop, with an inch shorter pitch?  There is no need to reduce the venturi diameter.

The second option is to power the Ringmaster with a good .15 engine; you'll still probably need to install
a larger capacity fuel tank(2.5oz?).   The engine change will require trying different size props that will
give appropriate speed for flying whichever stunt pattern you desire(O.T. or Modern).

For historical perspective,  I remember a friend who loved to compete in Stunt with a Goldberg Shoestring
powered with a SuperTigre .15D swinging a 9" x 6".   Best of luck;
Tony G

[Dan McEntee]

  If the engine is happy and a slower lap time is desired, why not  longer lines?  Ask the Dallas guys about Sean flying his Ringmaster on 65 foot lines. It is Fox.35 powered, though. He has licked up several pieces of hardware with that combo in both OTS and Classic. Said he had to let it out that long to slow it down and still keep line tension. I flew one of mine with a FP-25 on it on lines that long and it wasn't a problem.
  Type at you later,
   Dan McEntee

[Randy Cuberly]

I flew a 20 oz Ringmaster for several years in Old Time here in Tucson AZ.  I used an LA25 and it was a perfect combination with a 10=3 APC Prop on 60 ft (eyelet to eylet) .015 lines.  As I recall the LA25 Ran at about 10,500 RPM and the airplane flew 5-to-5.1 second laps.

Just set the speed you want with the prop pitch.  I also used a 10-4 APC at about 9700 RPM and it was a good combination but the 10-3 gave slightly more consistent runs, especially in Hot Weather (100+ degrees here in Tucson).

Randy Cuberly

[C.T. Schaefer]

I built a successful OTS Ringmaster and flew it in several local meets. It was a big hit! I was afraid it would be underpowered with a Fox .35 so built it for a McCoy. A McCoy .60 that is. It was fast, loud and very smokey. 70x .021 lines. One drawback was that the leading edge would crack on the last corner of the square loop! Fixed numerous times. Still have the plane. Sold the McCoy (dang!).  Planes name. 'Big Mac'   Cheers, TS

[Doug Burright]

Say what?! Gravity must be less where you fly, because we need Fox 35s and McCoy 35s to lead our Ringmasters around. A .15 will pull a solid-wing SIG Buster around the circle, but I have yet to see a .15 on 60' lines that would do anything except fly flat and level. Windy days are a major factor in our choice of engine selection, also.
But hey- we do have 2 paved circles and 3 concrete pads for grass circles, in a location that the City maintains for us!

[Jim Kraft]

Doug, You guys are just "plane" blessed. Now if you could get the heat and the wind to obey. All in all I have enjoyed flying there many times. It is kind of a landmark site for control line. And yes, I flew a Sterling profile mustang there a few years ago with a honk'n Fox 35 stunt that was way to fast but sure cut through the wind. I can not say much different for the weather in Salina. It is about the same. It can be dead calm in Abilene, and by the time I get to the field it is blowing hard enough to rip links of our log chain wind sock. Just some of the fun we flyers in Kansas learn to put up with.

[Larry Renger]

What is the story on the Brodak 15 compared to the OS 15 fp? 

[Jim Kraft]

I think it depends on which FP you have. The early ones were steel sleeves with baffled iron pistons. The later ones are ABN flat top aluminum pistons with three intake ports.

[Larry Renger]

That is interesting data, but doesn’t begin to answer the question. What is the comparison between all three engines, then?

[Brett Buck]

That is interesting data, but doesn’t begin to answer the question. What is the comparison between all three engines, then?

  There is no comparison.  Even their own specs show that the Brodak can probably be beaten by a Max III 15, or an Olympic 15. It's a mild 4-2 break motor to go where you might put an old baffle-piston 15 on "Junior" versions of 35-sized models. That's a good application, replacing a Fox 35 (or from another post, and ENYA 45!) is not a good application. They have a Brodak 40 for that.

    And of course, the 15FP *finished high at a world championship and several nationals*.

     The 15FP is not a particular powerhouse, but it's vastly more effective in a stunt plane that these ancient engines, but itself is a very mild sport motor by modern standards.

  Of course, this is just advice, no one has to follow it.

    Brett

[Dave Hull]

Larry,
Maybe we need to stage a direct comparison. Might be fun.

For history, I have an OS.15LA in a SCAR Goodyear. Ron Duly had a Brodak .15 he tried. I think he wanted to try it because of the success we have had with the Brodak .25's in Super Slow. After he ran the .15 once, and I called it a "Bore-doak" because it was so slow, he put it away....   If he's still got it, we could run them side by side so you could get rpms, airspeeds, prop sizes. And then back off some and see if you like the run for stunt. It would be easy if the bolt pattern was the same. I don't have a BoreDoak, so I couldn't say....

I also have an OS.15 steel fin we could run for comparison. Not sure I made a venturi for it yet. I don't know the condition of the engine, as it was second hand to me. Assuming it is at least average, you'd get what you want to know. Again, the hole patterns may be different.

The "Not-a-Monoline-Trainer" is set up for the OS LA, and we could use that if things fit.

Not sure who ended up with the engine dyno that Jed had. That would give you measurable differences between the three at least for static thrust with calibrated clubs. Did one of the Knights get that unit?

Divot McSlow

PS--Of course, if in your original post you aren't suggesting that you could go get one of these proposed fire-breathers, but actually have them, then bring your own motor (eBOM) and I'll help you try them out!

[Brett Buck]

Say what?! Gravity must be less where you fly, because we need Fox 35s and McCoy 35s to lead our Ringmasters around. A .15 will pull a solid-wing SIG Buster around the circle, but I have yet to see a .15 on 60' lines that would do anything except fly flat and level. Windy days are a major factor in our choice of engine selection, also.
But hey- we do have 2 paved circles and 3 concrete pads for grass circles, in a location that the City maintains for us!

       David and I flew flight-after-flight-after-flight - full AMA patterns of >500 point quality - with a 15FP Ringmaster including Napa Valley afternoon winds of around 15 MPH.  Paul tested his 15FPs in a Mike Dietrich Cobra.

    If you are talking ancient engines like Fox 15s, Max IIIs, etc, then yes, it will not fly very well. The Veco 19BB and 20FP are so overkill powerful that they are hard to handle without really knowing what you are doing. David finished high at VSC one year with a Veco 19BB so worn out it would/will barely start.

    Brett

     

[Brett Buck]

For history, I have an OS.15LA in a SCAR Goodyear. Ron Duly had a Brodak .15 he tried. I think he wanted to try it because of the success we have had with the Brodak .25's in Super Slow. After he ran the .15 once, and I called it a "Bore-doak" because it was so slow, he put it away....   If he's still got it, we could run them side by side so you could get rpms, airspeeds, prop sizes. And then back off some and see if you like the run for stunt. It would be easy if the bolt pattern was the same. I don't have a BoreDoak, so I couldn't say....

   It is definitely not intended to run like a modern sport 15, it is intended as a very mild 4-2 break stunt engine for airplanes like the Shark 15 (which is barely bigger than a 1/2A). It's not at all surprising that it doesn't work well for racing.

     Brett

       

[Howard Rush]

And of course, the 15FP *finished high at a world championship and several nationals*.

I can remember at least one Nats where there were four .15FPs in the top ten.

[Sean McEntee]

  If the engine is happy and a slower lap time is desired, why not  longer lines?  Ask the Dallas guys about Sean flying his Ringmaster on 65 foot lines. It is Fox.35 powered, though. He has licked up several pieces of hardware with that combo in both OTS and Classic. Said he had to let it out that long to slow it down and still keep line tension. I flew one of mine with a FP-25 on it on lines that long and it wasn't a problem.
  Type at you later,
   Dan McEntee

68', nose to handle

OK, there is a very light Ringmaster with an FP 20 on it that is too fast on 60’ lines. Turns out there is about 1/2 oz of tailweight lurking in the rear. So, do I constrict the venturi on the engine oe substitute a .15? The choices are an OS steel fin, a .15 FP or a Brodak .15? The plane has a 2oz tank and is a bit shy of duration to do the OT pattern.

In addition to longer lines being a much simpler solution to slowing lap times, its my theory that smaller models, flying on longer lines present better in square and triangular maneuvers.  Longer lines puts the model in a larger hemisphere, making the sides of, say, a square loop longer, thereby giving the illusion that the corner is tighter than if it were on shorter lines.  Just a theory, but between my own success and some guy from OK winning VSC with a ringmaster, I think that there is something to it.

Same is true for my T-6.  I judged a contest in Dallas and saw Joe fly his.  I don't know what line length he was flying but the model just seemed really "big" in the circle.  Needless to say, he killed it with that model on countless occasions.  When I built mine, and put a ST51 on it for both power and nose weight, I took it all the way to 70' nose to handle, and it will fly 5.6-5.8 laps with plenty of tension.  Veronique Beringer flew it up at Oshkosh last summer, and watching from upwind, the impression of sharper corners and longer sides in between was again noticeable.

[Larry Renger]

I do own Brodak, OS steel fin and FP, Torpedo green head, and Cox Medallion 15s.