Unfortunately Tom Lay is gone. He had a bunch  of parts. I would try Frank Bowman, he is listed in the vendors section. You might also try contacting Brian Gardner for one of his ABC sets that are a drop in replacement from what I have read and seem to be a better running engine.

Brian Gardner for one of his ABC sets

I vaguely remember hearing something about that. Is that ABC with a ring? Does it have the baffle, does it have different porting.

Oh, Randy this site "does" have the ignore feature, just don't want you to waste your time.

MM

Oh, Randy this site "does" have the ignore feature, just don't want you to waste your time.

MM

It does? I can't seem to find that button.

It does? I can't seem to find that button.

Bill, click on your own name to open your profile then you'll see a menu on the left that says modify profile, select personal message options then just add names to your ignore list. It's great, I've got like 4 guys on there.


MM   

My ST46 ABC sets are true ABC (no ring). True chromed brass liner and 27% Si piston. The porting is same as original and the piston is baffled as per original.

I take names on a waiting list and when have enough spoken for a batch gets run.

I currently have 9 sets spoken for and need a minimum of 15.

Aren't you the one who told me I need to start buying glow fuel buy the case and not the gallon?

  Yes. But I would gently suggest that the "move up to expert" plan shouldn't involve an ST46. You need a *conventional* stunt engine, that is, conventional for the year 2016, not 1976. That means a piped 40-75 (OS, PA or RO-Jett) or electric. The ST was becoming unsupportable even in terms of parts in the late 80's, not to mentioned being completely outclassed in terms of performance.
 
   In any case, I ran the ST46 from about 1979 to about 1988 (one of the last die-hards), and I flew A LOT at the time, because you had to. I never wore out a piston on an ST46 myself. The plasma liner is desirable because it solves the ring (and probably the inconsistency) issue, but it won't turn it into a 40VF.

  I can't find the "move up to expert" thread right off, but even an 46LA would be a better starting point, because at least you will be using a competitive prop. There are certainly a lot more of them around, with better parts support.

     Brett

     


   
   

   

I'm using a wide blade 11-6 running a steady 4 stroke. What would happen if I put on an 11-4 and ran it in a rich 2 stroke? Would it have more power because I could sure use it.

MM

I'm using a wide blade 11-6 running a steady 4 stroke. What would happen if I put on an 11-4 and ran it in a rich 2 stroke? Would it have more power because I could sure use it.

MM

   You can do that, but it won't improve the performance. As you run the RPM up, you will lose power faster than you gain performance from the prop. It's a less extreme version of what happens with 4-strokes and why they do so well with extremely high pitch props - the prop is less good but you make up for it by making the engine happier.

    Think something like a 12-6 Rev-up as a baseline. Most of the magic people learned about props was in this era, where you had to wheedle out every bit of performance. My baseline prop at the end was a 12-6 Rev-Up with a heavily modified airfoil, with about 5.8" of pitch until the last 4 stations, rising to 6.3" at the tip. The alternate windy-weather prop was a Rev-Up 13-5 cut down to 12 with a reshaped airfoil and a constant 4.8 helical pitch. That was only good in reasonable air density.

    To have much chance, you need to have a series of stock-style venturis ranging from the stock .157 (4mm) to about .181. Just take a stock venturi (wherever you can find one) and drill it out. Yhe 181 will only work (or be necessary) in pretty extreme hot conditions. I ended up running  a .173 almost all the time, with 10% nitro. It was too jumpy with 5% and the .173. Do NOT use all-castor, use a blend. Don't be stingy with the nitro. The last great stand of the ST46 was David coming in 6th at the 87(?) team trials running 15% Cool Power with a bunch of added castor.

    There are a bunch of posts where various aspects of the setup are provided. By the end of the road, pretty much everything there was to know about it was known. Along with the usual 400% overburden of bullshit. NOTHING on the engine needs to be improved in any consequential way and almost everything you hear about modifications and tricky or "special" parts is very wrong, as is anything about "softening it up", which if you are going to try to compete in stunt against a sea of piped engines and electrics, is the very last thing you need.

    It should go without saying that you want a relatively *small* airplane (600-630 square inches) and an all-up weight in the mid-upper 40s to low 50's at the absolute maximum. It's actually not all that  hard to build them in that weight range given the lack of hardware required. All of mine were in the area range as described and went from 43 to about 51 ounces. The very best airplane every made for the ST was one of the last serious ones, Ted Fancher's "Temptation" at 610 square inches. It also made a dandy 40VF airplane...  I would recommend something about iike an Imitation, which flew fine at 57 ounces.

    Brett

I've added you to the list mate

Brian

Put me on your list. I am already on your list for my "paperweight ST 51".

Yes & No .

the beauty of model aviation is you can do something Really Modern .



the ABC sets come with rod & Gudgeon ?  , Brian .
Ive met someone who says He has EIGHT ABC .46s and theyre so much better theres no comparison .

Man, you're right about that.

 
I got this engine on a Humongous I bought. 630 sq in and 49oz and it was set up with a Rev Up 11-6. It was oil soaked so I took a MAS 12-6 and cut it down to 11" and rounded the tips. It's a club but I needed the nose weight and it's got good blade area at the tips. Now if I can't find another rev up I'm thinking Zinger 11-6 with a thinned airfoil at mid prop?
  

  One thing about props, you never know for sure what is going to work in a particular situation. I would suggest getting about half a dozen of each type you can get (the Master Airscrew wood types looked to be a pretty good starting point to me), and keep one stock as a reference, and modify the others. I also suggest you get am *original* Y&O prop, or a "Bull" BY&O prop - not the Brodak Y&O which is different. Doesn't matter which size or pitch, because all you need it for is to see what the prop airfoil should look like.

   Failing that, strip the finish off whatever prop you have (wrap a paper towel around each blade a few times, then soak with lacquer thinner for a few minutes, and it will come right off). Clean up the mounting face to make sure it is flat, and then put it on the gauge and even up the pitch. Adjust the pitch, if needed, by scraping with a single-edge razor blade. Work from the center out to the tip. Wen you get each station the way it should be, then do long scrapes to make sure it is a flat and "fair" surface. Then balance the prop by sanding the airfoiled side. If it want to hang "level" one way, sand more on the LE of one blade and the TE of the other to shift the CG towards the shaft.

   Take a pencil and using your fingers as a marking gauge, draw a line on the airfoiled side of the prop, at about 30-35% of the chord from the LE. Start scraping off material between the line and the TE, being carful not to actually touch the TE itself with the blade. The idea is to make the aft part of the airfoil nearly flat from the TE to the line, with the TE about 1/64 to 1/32 thick.  Switch from side to side to make sure it stays even. It's actually pretty easy to keep it adequately even and balancing it again will get you very close.  Once you get the mostly flat part done, you will have a sharp edge along the pencil line. Take the blade and scrape the edge off of it, just enough to make it round and smoothly faired into the aft section but not to remove too much material. . Again, use balance to make sure you stay even.

   Once you get that rounded off, then take 240 grit sandpaper and smooth it out. If you scraped it properly, it shouldn't take much sanding. Smooth and round off the LE, again, just enough to make it a smooth airfoil. Then refinish it with the Satellite City finish method that uses thin Hot Stuff until it is reasonable smooth and shiny.

  There is definitely an art to doing all this, and definitely an even more mysterious art to figuring out what to do to make the engine run the way you want, and fly the airplane in the conditions you want. With practice I got to where I could to the rework as described in around 15-20 minutes but that was pretty far down the road.

   Don't necessarily go for wide-blade types. They work well sometimes, in particular, in dead air, but you burn a lot of power, and they are absolute death at times in any sort of wind. A narrower blade with more diameter is more efficient, and with limited power, more efficient is a good thing, usually. You should start with a straight helical pitch distribution as measured by the gauge. You should then get a baseline, and then add pitch at the tips to see what happens to the engine and the performance. I have not found a case were *dropping* the pitch at the tips helped anything, at least on 4-2 break engines.
 
    For a Humongous it is probably not critical to get maximum performance, since you will want to fly it pretty fast anyway. But you will likely get more performance with 11.5 or 12" diameter, if the engine is good enough to handle it. I have run 13" props on the ST in some conditions and it would be fine on strong engines, even a 13-5 Rev-Up (which stresses the engine more than a 13-6, in the air at least). But most people, myself included, wound up between 11.5 and 12.

    Brett