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General control line discussion => Open Forum => Topic started by: maverick11359 on July 17, 2022, 05:52:16 PM
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Hi Guys, just wandering what prop ,fuel ,mixer ,line length and run speed (4x2x4or just solid 2 )combinations you think best or run with your ST46's .I'm presently running 11.5 x 5.5 resin , 10 nitro , 61ft - W tip to handle, 5.3 second laps in 4x2x4 combo. Just flew last weekend in moderate to strong wings and had a hard time with the top of vertical and overhead maneuvers. Just thinking about experimenting with different combinations for example running a solid 2 speed in strong winds. Maybe a 12x4 or 12.25 x 3.75 to help push up against the wall I seemed to be hitting overhead.
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You don't mention what model it is and what it weighs. It helps with the equation. Being more specific on the brand of prop will help also. On a ST.46 I don't think a flatter pitch will help you much because the engine won't rev to the point it is effective. A wider blade than what you are using may be more effective. All props are not the same, even among the same diameter and pitch. One 11.5 X 5.5 might not work but another brand will. It takes experimenting and test flying. If it's a big, draggy model that is over weight, then you have an uphill battle.
Type at you later,
Dan McEntee
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Mine'll pull 60 Oz with a .210 intake & 12 x 5 T Flite . steady . Less plane for in any wind .
Needs the ' bouncey ' run , said should have same compression flipped Forward & backward . Ring gap at the transfer , not Ex side .
Ran a 40 with a 11 x 4 & 9 mm intake . Sucks the juice .
some rpm / prop figures . http://sceptreflight.com/Model%20Engine%20Tests/ST%20G21-46.html
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You don't mention what model it is and what it weighs. It helps with the equation. Being more specific on the brand of prop will help also. On a ST.46 I don't think a flatter pitch will help you much because the engine won't rev to the point it is effective. A wider blade than what you are using may be more effective. All props are not the same, even among the same diameter and pitch. One 11.5 X 5.5 might not work but another brand will. It takes experimenting and test flying. If it's a big, draggy model that is over weight, then you have an uphill battle.
Type at you later,
Dan McEntee
Hi Dan, My model is a JG59 I named after my father that draw it up but never built back in 1975.It's cord thickness and wing shape is an enlarged Jim Van Loo 1960's Chipmunk wing at 59"span. It's weight after trimming adding lead to nose and outer wing is 56.5 oz's ( started at 54oz's).The prop is resin built 1970's Brian Ether prop from that period, built back then for the ST46.
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Maybe a 12x4 or 12.25 x 3.75 to help push up against the wall I seemed to be hitting overhead.
That's not nearly enough pitch. You *might* get down to as little at 4.75-5" on a very strong engine with a enlarged venturi, but *no chance* with the average engine. Im any case, if you are having trouble coming back into the wind in the overheads, this will make it worse, rather than better.
11.5-5.5 is about right, depending on the size of the airplane and the quality of the ring.
I have posted my nominal ST46 setup several times, might want to search for it. Note that it is almost purely stock except for the venturi, you don't need any "improvements" aside from having a good ring, preferably a good factory ring. .173 venturi, 10% nitro, 18% 50/50 oil. If you need more power, use more nitro before you use more venturi. It has no problem with up to 30% without changing the stock head clearance.
Brett
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Brett nailed it. On my ST46 modified Super Chipmunk I used a little more pitch 11.5 x 6 wood prop & a chip muffler. Best sounding & best flying combination that I had. 64.5' lines center of handle to center of airplane.
https://youtu.be/ql-6MXh8KgU
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Did SuperTigre ever make the 46 with a chromed sleeve?
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Wow, that’s a really loaded question.
At one point in time I had at least two dozen ST 46 engines that were reworked (Randy Smith, Big Art, Big Jim, and others) and others some were stock from the factory. They all ran great but all had the same problem, after about 5 to 10 gallons of fuel the power would drop off a little and you could tell it was time to change the ring. Thinking it was a fuel problem I switched to all caster fuel, it seemed the normal SIg fuel made the rings last longer mainly because the carbon was washed away from the piston, the all caster fuel had the most carbon on the piston ring groove & piston. I would purchase 6 factory rings at a time and keep the best fittings rings and sell the rest, after sanding the inside of the cylinder lightly to remove the glaze from the inside, sometimes that helped restore the power back to the engine.
Props: The best prop at that time was a 11 X 6 EW Rev Up with a under camber sanded into the back side (,030) of the last 1”. This really helped in the Hourglass & Overhead’s to keep the line tension where i liked it. I tried a bunch of props but in the wind I found that 12 X 5 W Rev Up was slightly better in strong wind.
Line Length: Most of mine were flown on .018 X 64’ lines with lap times around 5.2 to 5.4.
Model Size: The Magnums I was flying all ranged between 52 to 58 ounces with the lightest being the I Beam Magnums around 46 to 51 ounces.
At this point I switched to the ST 60 and that in itself, was another story, with the introduction of the
Smith PA 51 & 60 were the engine of choice out there.
Later,
Mikey
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I flew several of these engine from several reworkers mentioned by Mike. I’m at 1,800 feet use 10% caster, 12% Klots and 10% nitro. 62 foot .015 lines. I tried dozens of props and found a Rev-Up 11.5 X 6 the best. Hard to find now. So I tried a APC 11 x6. Seems very good.