Finn,
I think the
flange does make some
difference, just don’t know how much. The reason I think that is
that the stock manifold has slotted holes at two of the exhaust ports,
allowing
for the engine and/or the manifold to move/grow without affecting the
other or
breaking the studs. I did the same thing on my exhaust system.
The bends
came from R.G. Wagner and is 304-SS
material, the same stuff that Ed Anderson has used successfully for
many
hundreds of hours. They are about 1/8” thick which absorbs much of
the heat stresses, similar to a cast iron manifold. Each bend passes
through a close tolerance chamfered hole and is welded on the back side
nearest
the exhaust port. I didn’t wrapped it so that I can inspect for cracks
and to allow the heat to escape. So far, no cracks. I do have a Zetex
aluminized fabric heat blanket on the upper and lower cowl in the
vicinity of
the exhaust. It made a significant difference in cowl temps.
Mark S.
From:
Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Finn Lassen
Sent: Wednesday, July
26, 2006
10:09 AM
To: Rotary motors in
aircraft
Subject: [FlyRotary]
Re: Joe
Hull's OSH
Trip
- Part 2
Sure looks
good! Too good to change.
I don't think that the flange has much significance.
Time will tell, but you may find that the thermal stresses are where
the bends
are welded to the collector.
Now, you do have fairly long bends which may
absorb the expansion. Then again, the length of the bends may make it
worse.
A lot of factors here: difference of EGT of the three rotors, airflow
over the
outside of the bends and collector, vibration, etc.
In any case, please keep looking for cracks in the collector where the
bends
are welded to it.
If so, you'll have to at lease cut two of the bends at a straight point
(near
port?) and slide pieces of tubing over the cuts. Better would be to add
actual
expansion joints.
How thick is the material of the collector?
If this were a pusher, definitely safety wire the collector!
Finn
Mark R Steitle wrote:
Finn,
Maybe that’s
why some of the
aftermarket flanges are one piece. That’s how I made mine for that
very reason. So far, so good.
Mark S.
From:
Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
On Behalf Of Finn
Lassen
Sent: Wednesday, July
26, 2006
9:37 AM
To: Rotary motors in
aircraft
Subject: [FlyRotary]
Re: Joe
Hull's OSH Trip -
Part 2
Ground running
won't necessarily get you into that
thermo cycle range. Seems you consistently have to get above 5,000 RPM
before
anything happens.
No expansion joints: it will crack.
Unless you use ridiculously thick material. Which is probably why the
stock
Mazda manifold is so heavy.
Finn