weight vs hp and BSFC and to some extend, cost, is what
counts. I remember the bureaucrats work on the RO80 and the Spider. There
was no factual basis for their explanation than. So why wasting our energy on
it now.
----- Original Message -----
Sent: Sunday, October
16, 2005 7:38 PM
Subject: [FlyRotary]
Displacement - Again?
Been there, done that {:>). If you are going to
compare the power production of 13B rotary engine with a
normal reciprocating engine, then the accepted standard for a power cycle
(for a four stroke) is 720Deg crankshaft degrees of rotation. 720 degrees
of a reciprocating engine has all cylinders firing be it a 4,6,8 or 12
cylinder engine.
Clearly the 80 CID or 1.3 Liters comes from simplistic
sum of the two 40 CID chambers per rotor. The 2.6 liters takes a bit more
explaining.
Where I believe the controversy comes in is that
720 degrees of a rotary leaves two faces of the 13B yet
unfired. For all six faces to fire it takes 1080 degrees of
crankshaft rotation. Each rotor face rotates 120 rotor degrees for a
complete cycle- since the e shaft is geared 3:1 then 120 deg rotor
rotation = 3*120 = 360Deg of E shaft rotation. Or another way to look at
it is 360 deg of rotor rotation ( a complete rotor revolution) = 3*360 = 1080
deg of e shaft rotation.
Now you can argue that the rotary has not finished its
combustion cycle (all chambers firing) until all six faces have fire (1080
deg) - however, the accepted standard for a complete cycle of a
reciprocating 4 stroke is 720 degs.
So IF you are interested in comparing oranges and oranges,
then its generally
accepted you compare only 720 deg of the rotary's rotation to equal the 720 deg
of a normal 4 stroke reciprocating engine.
IF you do accept that -
then that means 4 rotor faces have gone through their cycle in 720 deg of
e shaft rotation. So at approx 40 CID per face we have 4 x 40 = 160 CID
for the 720 deg cycle. And that turns out to be 2.62 liters of displacement.
Its really no different than adding up the
total displacement of all the cylinders in a reciprocating engine which do
happen to complete a power stroke in that standard 720 deg. I think the
fact that two faces or (80 CID of displacement) have not yet fire with the
rotary is what bothers folks in this comparison.
But if you are going to compare the power of the two different
designs of engine you have to pick one or the other as the standard of
comparison. And keep the parameters the same for both engines. For
example:
If you believe the cycle of the rotary is not complete
until all six faces have fired then you have 6 x 40 = 240 CID in the 1080
degree rotary cycle.
We could insist that the reciprocating engine be compared to
the 1080 deg rotation of the rotary, but then you would have to increase the
effective displacement of the reciprocating engine to include an additional 1/2
of its displacement since it will have gone through another 360 deg of rotation
to match (720 + 360 = 1080) the rotary cycle of 1080deg. That way you
again have oranges and oranges.
But, in that case both we and the recip folks could
boast about even more HP than we do now {:>)
Since I am mainly interested in comparing a rotary with the
reciprocating engines production of power, I adhere to the 720 deg standard for
the comparison.
Not taking any sides , but someone asked where the 2.6
liter figure came from and I hope I have answered that.
----- Original Message -----
Sent: Sunday, October 16, 2005 9:21 PM
Subject: [FlyRotary] Re: flyrotary_Web_Archive Re:
Banishment
> Hi Dave,
>
> OK, one revolution of the e-shaft is 1/3 revolution of the rotors. So
> each rotor has had one intake event. Each face has a calculated
> displacement of about 650 cc. Two X 650 cc = 1.3L. If you can
explain
> why it's 2.6L, maybe I can send Paul an apology. Or are you just
> trying to get my goat? :)
>
> I'm not trying to create a big discussion on the displacement of the
> rotary, I just want to understand where that 2.6L per revolution number
> is comming from. I haven't been able to see it. I think Paul
gets it
> from comparing to a piston engine, and I agree that the 13B compares
> closest to a 2.6L 4 cycle 4 cylinder engine.
>
> Bob W.
>
>
> On Sun, 16 Oct 2005 16:27:59 -0700
> David Leonard <wdleonard@gmail.com> wrote:
>
>> Monty, Glad to have you and you know you will always be welcome here.
>> However, you are wrong and 'he' is right about the displacement of the
13B.
>> It is 2.6L or 159.6 cubic inches to be more exact.
>> That is the volume of intake on one revolution of the e-shaft.
>> But I think you knew that, you were just trying to get his goat.
;-)
>>
>> --
>> Dave Leonard
>> Turbo Rotary RV-6 N4VY
>> http://members.aol.com/_ht_a/rotaryroster/index.html
>> http://members.aol.com/_ht_a/vp4skydoc/index.html
>>
>> On 10/16/05, Monty Roberts <montyr2157@alltel.net> wrote:
>> >
>> > The doctrine of immaculate ingestion. Whereby molecules of air
and fuel
>> > magically migrate into a very small, very perfect
engine,unsullied by the
>> > mere laws of physics, thereby creating the salvation of the world
through
>> > massive power levels.
>> > In the protestant tradition of placing the individual at
the front of the
>> > line rather than at the bottom of the church hierarchy, I will
henceforth
>> > place all replies at the TOP of each post.
>> > Monty
>> > Which doctrine was that Monty?
>> >
>> > Bob W.
>> >
>> >
>>
>
>
> --
> http://www.bob-white.com
> N93BD - Rotary Powered
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>
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