I repeat what I've read here; I'm not sure I've even touched a tuned pipe.  Short story -- it provides engine regulation.  Rig up a tuned pipe so that it's "too long" for the RPM in the conventional sense, run a venturi that's "too small" for maximum power, and run the engine "too rich" for maximum power.  The result is that the tuned pipe will hold the engine back from it's maximum power capability in a way that regulates its speed.

Done right, you can even get the engine to speed up a bit under load, although I think most folks aim for a constant engine speed.

So it's doing what the electric setups do (or, if you follow the historical timeline, the electric setups endeavor to do what tuned pipes do).

   The alternative method of controlling them is a common topic of discussion:

You leave out the alternative "real" method of controlling them, suitable for anyone content to stay in the bottom half of Expert.   The idea is to carefully select a low-pitch prop (around 4"), use a "small" venturi that's carefully selected to your prop and plane, and run them in a rich two-stroke (or, very occasionally, a rich fast 4-stroke).

No stack of head gaskets, no modifications to the inside of the engine

There's a happy spot in there where the thing will pick up power in maneuvers but won't "run away" (I've described the technique that I use somewhere).  It tends to be more fickle than the run you can get with a pipe, and not (I'm pretty sure) as well regulated.

It requires playing with venturi, needle, and prop -- and the prop that works perfectly on a 48 ounce whatever is not the prop that'll work on a 64 ounce Atlantis (basically it's the Impact's favorite uncle).

I came in precisely in the middle of Expert at the NW Regionals (several places behind Brett) using a bone stock OS 46LA in a 64 ounce Atlantis, with the only "mods" being a hand-turned venturi and a Tower 40 muffler -- and the only driver for that Tower 40 muffler is that it's lighter than the OS E3030.  Otherwise the engine was tuned just by choosing the best venturi size and needle setting for the plane and prop.  No special backplate, no changes to the liner, no head shims -- just as it came out of the box.

I understand, tuned pipe is the best solution to run 2-stroke engine in the most efficient way.

Very possibly not the most efficient, at least if you mean that in the engineering sense.

But the majority of stunters who fly with 2-stroke engines - they utilize 4-2 brake and uniflow tanks. No pipes.
The question is still open))

No, Brett and I answered the question as stated. 

Now you're alluding to a different question, and it appears to be based on data that doesn't match what I see at contests in the Pacific Northwest.

On your statement that the majority of stunters who fly 2-strokes fly a 4-2 break -- nope, at least not around here.  There are some, still, but there's a lot of folks who fly Schnuerle engines in a wet two-stroke as I described, or a solid 4-stroke.  There's a good minority who fly 4-2 break engines, but they generally don't win contests.

So -- what is the question that "isn't settled"?  Is it why people don't fly pipes?  I don't know -- but I suspect that people just like the setups they have, or they don't want to shell out a bunch of money.  There's a few vocal folks here that just can't seem to make the connection between the fact that the people who win at the National and world level fly tuned pipes or electric -- but that's their problem.

I could see, if I weren't focused on getting better, that I might want to stop at a 46LA engine and a wet-2 run.  It works pretty good, it'd work better if I dinked with my current setup some more, or went to a bit lighter plane.  But I don't want to stay in under-Expert.  While I don't think I'll win Expert any time soon, I at least want be doing a credible job of nipping at the heels of the top pilots.

So I did look at those leader boards.  I decided that it was either electrons or pipes, and right before I ripped my current plane apart to convert it to electric, I inquired of Randy Smith on the cost of a tuned pipe setup.  I decided to go electric, but it was an either/or decision -- I didn't see a viable third option to getting my equipment to the point where I'm not being limited by my powerplant.

Hello

Pipes and electric have won over 4 strokes and 4/2 break engines and the only way we could use a two stroke efficiently on a pipe making big power will be changing the stunt event 
 Something like those fun combat speed stunt runs how quick can you complete a pattern without crashing,  probably need 90 or 100 ft lines and fly like they did in the 1940's but with a 40 pylon engine set up, sounds fun but it would not be precision aerobatics!

Regards Gerald

What was the real reason for introducing the tuned pipe engines to the stunt ships?

Jerry

I wrote an article about this  years ago, I will try to find it,  In addition  to what you have been told. The  simple thing the  pipe setup did was let Pilots use modern Loop charged engines, The  40s we were setting up had more power than the  ST 60, This was achieved by using the  power of the  modern engines, and  launching at 11,000 RPMs, instead of 8600 RPMs that  typical stunt engine used.
The results was a lower pitch prop running much faster, greatly increasing the torque availble to power the plane.  The  lower pitch prop, also  added speed stability to the plane, as did the  pipe. In combination they both worked together wonderfully.
Most of the  1st engines  used  were  40  , 45 , 46  size, These would  easily fly  70 ounce 60 inch Stunt ships.  Not something  you would  expect in a  40 size engine.

Regards
Randy

I have a few 40 FSR engines which I am told are basically the V series but with side exhaust. Been running them at a wet 2 as I have not found any Side to rear headers for them in order to attach a pipe. Those engines are scary strong but a bear to keep them from wanting to run away. They really want to run at stupidly high RPM's

I have a few 40 FSR engines which I am told are basically the V series but with side exhaust. Been running them at a wet 2 as I have not found any Side to rear headers for them in order to attach a pipe. Those engines are scary strong but a bear to keep them from wanting to run away. They really want to run at stupidly high RPM's

Have you checked with Randy Smith about headers?  I know he had one for the 46LA when I asked.

I think rear exhaust and pipe in stunt ships made them more aesthetic, cleaner, and quieter. Now, slowly but surely stunt ships are becoming electric. So I bypassed tuned pipe and from electric RC jumped into electric stunt.

   Well, that is true to a certain extent, but it also  *made the performance drastically better*, to the point that it is nearly a different event than it was before. No other change since Aldrich put the "precision" in "Precision Aerobatics" was any change bigger and more important and had a more dramatic effect on performance.

    Electric is probably going to be a net improvement over low pitch tuned pipe engines, and performs better in most conditions, and with some improved reliability over the very accomplished piped runners, but not overwhelming. It will be a *drastic* improvement in reliability and performance for less-experienced and those still trying to compete with muffled 4-2 break engines  - because they missed the boat the first time 30 years ago. This is a second chance for them to get what the rest of us have had, more-or-less, since the late 80's .

   If your point is that if you are starting back on a competitive plan now, yes, by all means, start with electric, because that's where everyone will end up in a few years.

   If your point is that it was all some sort of affectation, I would have to disagree with you on that one. Ted Fancher, David Fitzgerald, and I watched one flight of Paul Walker's at the 1987 or 88 Golden State meet, and Ted flew the airplane. We all agreed, after watching only a few maneuvers, that we had to switch or we might never win another contest. The results are well-known, and the results so dramatic, that the guys who "knew better" became convinced we were all cheating somehow.   And never learned a damn thing, even though *we told everyone exactly what we were doing, why, and how they could do it, too*.

      Brett

   

In the end Compared to fossil fuel, the energy storage capability of the battery is less impressive. The energy by mass of gasoline is over 12,000Wh/kg. In contrast, a modern Li-ion battery only carries about 200Wh/kg. IC RUULLLES. Methanol is somewhat less than gasoline but............You can't compete with a couple million years of stored energy.

   There's no question that the energy density is higher for any common fuel. That's why Formula 1 cars are not electric. But for stunt, it just has to be good enough, and that threshold was crossed 20 years ago. So you use the advantages, like better repeatability and drastically better corner RPM control to their advantage.

    The other factor is that while IC is just about as good as it will ever be, there's still plenty to learn with electric, and even what is commonly known now makes it at least as good as the best IC systems. It's not overwhelming or a quantum leap like ST60 to tuned pipe to the point you immediately obsolete the older version, so it's not a show-stopper for IC, yet. But it will be soon enough.

    Brett

Hello

Current Formula 1 are hybrid Electric/Petrol 1.6 litre engined but Formula E (also known as Formula 1A) is not far behind in the 0 to 60 stakes  2 vs 3 seconds but the main problem of switching Formula 1 to electric only seems to be sound quality for the crowds.
 "The FIA announced in December 2019 that Formula E would be given world championship status from the 2020–21 season" 

  That, and the batteries will not last long enough for a regular race. First few years, they switched cars at pit stops because the battery in the first one was dead. They are fast, but just like a Tesla, yes, you can put it in Ludicrous mode, but if you drive it at full tilt, it will run for about 5 minutes. A Dodge Charger Hellcat, run similarly will go for about 50 miles.

    The regular F1 engines are turbocompound engines, much like a Super Constellation, implemented electrically instead of mechanically. The exhaust turns a turbine, which turns a generator, that charges the battery. The battery then either spins a motor attached to the crankshaft in classic turbocompound implementation and/or spins a motor that helps the turbocharger spin up faster to avoid turbo lag. It also has regenerative braking to charge the battery like a conventional hybrid. With that, the battery will provide boost for maybe 20 seconds/lap.

   It's pretty simple, there is only so much energy density, and any form of practical electric system using a Li-Ion battery is much, much lower than one using gasoline, methanol, diesel, etc, in terms of energy density. But for stunt, it was "good enough* 20 years ago (and hasn't really gotten much better in power/weight). Nobody currently running electric is making it through a stunt pattern using, say, a 12.5-3.75 Eather 3-blade, because that sucks up far too much power. If you tried to run it on the ground for 45 seconds like we normally do, it would probably melt.

    Fortunately you have compensating factors that make it so you don't need to run the extremely inefficient props used on tuned pipe engines, and as Paul and Chris have shown, the lack of vibration allows you to build the airplanes much lighter.

     That's not any sort of dig on electric, its plenty good enough the way it is.

       Brett