----- Original Message -----
Sent: Sunday, January 25, 2004 8:58
AM
Subject: [FlyRotary] Re: Torsionals
Tracy
Crook wrote:
Don't know if anyone has commented on this
already Pete, but yes, the single rotor does have torque
reversals.
Don't know how much of a problem this
will be but the torque signature (IGNORE RPM FOR THIS COMPARISON, it
doesn't matter) will be the same as the three cylinder piston
engine. Raven had a challenging time developing a redrive for the
Suzi/Geo 3 cyl. engine if that is any clue.
Tracy
If the two
rotor is similar to a 4 cylinder 4 stroke piston engine, wouldn't a one
rotor be similar to a 2 cylinder 4 stroke engine? Lamar has published the
plots many times showing no torque reversals for a two rotor but very
strong torque reversals for a one rotor.
--
Perry
Ahh yes, the never ending debate on how
to compare the rotary with a piston engine.
The reason I said to ignore the rpm when
comparing torque signatures was to compare ONLY the relative torque
amplitude variation of the engines. The two rotor engine looks just
like a 6 cylinder in this respect. Yes, I know the 2 rotor rotary
only has two power strokes per rev but they are 50% longer (270 degrees vs
180) than those of a piston engine, thus, they overlap exactly like
those of a 6 cyl. This is relavant because tortional resonance has
nothing to do with rpm that the system happens to be turning.
The torque variation represents the amount of
excitation energy fed into the system. The higher this
energy, the more critical the damper is if the system has to spend any
time at or near the resonant point. In terms of this
excitation energy, the one rotor probably has double or more the
amount that a 2 rotor has (all else being equal). Notice that this
excitation energy is not directly related to engine
horsepower.
Somehow I doubt that I have made things any
clearer.
Tracy
Yes
it does make it clearer, thanks. I thought about that after I posted the last
message (maybe I just reread your previous message!). It is clear that the
PSRU will be under more "stress" with a one-rotor. Has anyone ever bolted your
PSRU to a one-rotor? Do you even approve it for a one-rotor? --
Perry
Obviously, I am working on that for my One-Rotor.
There is a list of design features influenced by the running
characteristics of the engine. To name only a few - flywheel, idle speed, flex
coupler, redrive - have an influence on the impact of torque dynamics. I can
not say at this stage of development what the solutions will look like. One
observation I made on the POP engine on the test stand was, the attachment of
the load prop to its shaft had to be better then a couple of big set screws.
It had to be taken out after two runs (5Min) and I added a regular key to it.
And that in spite ot a simple industrial rubber coupler.
The good news is, that all this was test stand
set up using HDW mostly picked out of my junk boxes.
Nevertheless, the data will not be
ignored.