Please school me on PA 40's. I think they made a big case and light case version? Is one version call the Merlin? Are some abc, is there side and rear exhaust? Can you use a muffler or need a pipe? Does it make more power than LA46?
There are (were) two of them - the PA40 (regular case) and PA40UL (ultralight). The original PA40 used the same case as the other Nelson engines at the time, I think the same as the pylon engine, and then later used for the 51, 61. and 65, essentially compatible with the 40/46VF, each other, and the RO-Jetts, with minor tweaks required to fit any of them interchangeably. There were/are side exhaust and rear exhaust versions (side using the combat case, I think).
The 40UL is smaller all around and somewhat lighter. I think it is about the same as the Aerotiger 36 but I am not sure. They run almost exactly like the original 40 as far as I can tell. I have only seen rear-exhaust versions, use the Aerotiger for side-exhaust.
All of them are AAC, as far as I know.
Any of the will run on a muffler, presumably, although I can't say I have seen anyone do that. The timing is the classic hard-breaking 136 degree exhaust duration. I only ever ran the original and piped, of course, since that is the way it is competitive.
Set up properly (as it can be, see below...) it is a vastly more effective stunt powerplant than a 46LA, this is a real competition engine and has had a NATS win and numerous high finishes. It is a vast upgrade over 4-2 break engines and muffler sport engines like the 46LA.
Having said all that, and despite Paul Walker having won the 94 NATs with it (which I note is **30 years ago**), I found it to be extremely fussy and hard to get set correctly to have decent power without explosive 4-2 breaks. I *sort of* got it OK in the Midwest in the humidity and elevation, but it was one of the most difficult engines we ever tried in terms of excess power boosts. You could tame it, but then it had a lot less power than the obvious alternatives. Paul and I, completely independently, gave up on it at about the same time, for the same reasons, and went back to the 40VF - which was like magic and ridiculously easy to fly by comparison. It was difficult in exactly the way Kafin was talking about, the breaks were far, far, too aggressive and powerful ,and you didn't have enough power to run it in a 4 all the time. I eventually got an OK system by pulling the pipe way out, and running 3 1/4 pitch, launching at 12,000+. Then I went to Muncie and it was absolutely hopeless.
The early marks of the PA61 has the same sort of issues but was so much more powerful that you could run it in a 4-stroke all the time and at least with the spigot venturi, avoid the break most of the time. Someone came up to me at the 2002 NATs and congratulated me on how well my Saito was running! Nope, PA61 pumped to the gills and thundering around in a constant 4. Later marks of the 61/65 made some internal changes that reduced the problem. Ted and I run RO-Jett 61s precisely because it *doesn't* to this, ever, in any conditions, and can run very nicely across the break, smooth as silk - like a giant 46VF.
If you have a PA40, just use it. If it is an Ultralight, PM or contact Michael Scholtes, his ran absolutely great, even 5 feet above sea level and 45 degrees F. If you don't, then I would instead suggest you will have a lot easier life if you find someone with a 40VF, 46VF, PA51, etc. Everyone has all these and they are just rusting in drawers since they have been supplanted by PA61/65/75, Jett 61, and much more so, electric.
Brett
p.s. I note that if you looking for an alternative, Randy sells (sold?) AAC cylinder/piston assemblies for the 40 and 46VF, which saves some weight, which is the only legitimate beef anyone ever had with the VF.
Topic: PA 40 (Read 1755 times)