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.
>> >
>> >
>>
>
>
> --
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>
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