Martin Morgan wrote:

Well I've talked about it before and even mailed Tracy off list. But it

is

finally going to happen. After this coming weekends jolly flight and
beat-up, I'm going to pull my Pitts apart.

I will have to rebuild 51% (or rather, build 51% of a new Pitts and use

49%

of my existing one) to qualify for experimental, so this will still take

a

while.

I intend to use a N/A 13B with a bit of porting.My current Lyco should

be

putting out something over 200hp and I don't want any less than that!

(more

IS better). I'm hoping that Tracy will have the higher ratio box out

soon

that he mentioned working on a while back (any chance Tracy?).

My main concerns are the gyroscopic loads. Tracy believes that his

Gearbox

can handle Advanced levels aeros if the output shaft is replaced as part

of

seasonal maintenance. But what about the gearbox mount and engine mount?
(and the rotors themselves for that matter, I'll use the lighter late

model

ones to help with this)

For those Australians on the list that sent me their email addresses,

Thank

You! BUT I managed to lose all of them along with some thousands of list
mails in a lesson on Linux email servers (what's a backup?). Please do

mail

me off list and I'll try not to be so stupid in future...

Regards to All

Martin Morgan
Pitts S-1S
martin@i-byte.com.au

You will probably need peripheral ports to insure that you have over 200

HP.

We will be testing Tracy's 2.17:1 gear box and the rotors in my engine
for gyroscopic loads with carbon blades when I get back from your
country. I assume you will use a composite prop.

It will be an inevitable outgrowth our test on the LAEV
prop hub. We plan to nod the prop dyno at a 60 degree per second rate
constantly while running the engine at 6000 RPM WOT. This is how
Butch described the test:

"That's one hell of a SCARY big 240 HP Fan to just turn loose
while developing 360 deg gargantuan gyroscopic forces."

It should be a rather exciting experience. We are thinking of charging
admission to view the tests :-)

Paul Lamar

I'd love to see it myself! (and where will you be standing?  ;)

As far away as possible.

I was planning on composite or wood. The LAEV prop would be brilliant,
although coming out of a tailslide it is easy to do over 180 deg in a
second.... (I currently pull the power at the last moment for these as I
don't trust the lyco that much either). Don't know what the rate would be
for a Lomchovac, but they are done WOT.

Martin Morgan

I am going on what the Skyranch Engineering  manual says.
They say, on page 436-437, that with a 40 pound metal prop
(blades only), a prop RPM of 1500, a five foot diameter prop and
a pitch change of over 60 degrees per second will permanently bend the  
prop flange on a Lycoming. As I recall the bending moment involved is 
600 foot pounds. They used a one turn in six seconds flat spin as
an example.

Paul Lamar
 
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