George
I concur. Double press fit it is. And yea I'm lucky to have a great
machine
shop next door. It ain't cheap though. I'm still open to advice on a
perfect way to do it and I'll foot the cost of doing the two test
housings.
They will look like Swiss cheese with the other holes I am putting in
there
as well.
Paul my friend you have a habit of side stepping an issue you don't want
to address. You would make a good president:) The issue that has always
concern me IS NOT ABOUT EPOXY TENSILE STRENGTH or several different ways
(all satisfactory) for holding the inserted tube in. I repeat my concern
has always been about epoxy 's water sealing ability under the
circumstances
we plan to use it. With a good interface fit then epoxy is non issue and
we
have the advantage of warm water heating the intake manifold. Freeze plugs
in the blocks are only interface fits and they don't leak right?
Cary do you have any pictures of how you finished the outside of the
housing?
Cheers
DougFir
" You could always make that coupon sample I was describing.
Put it in the freezer for 24 hours. Take it out of the freezer
and bake it in the oven for 2 hours at 200 F and then repeat
500 times. Get back to me with the actual count :)"
"There is zero tensile load on the tube."
Notice I did not say anything about applying a load to the
sample. So boil it in antifreeze solution instead of sticking
it in the oven. The intent was to check the seal integrity and
not the strength.
BTW the radiator tubes you may have in your car are more likely
sealed with epoxy to the header flanges.
Sorry I should have been clearer. The bond to the aluminum was
exactly what I was talking about. If the bond fails it starts
leaking. I was not purposely side stepping the issue.
I am not against a press fit it is just difficult for the
average builder to accomplish. First the hole must be bored
to the EXACT size in the rotor housings +/- .001 and then
the aluminum trimmed to fit the inner trochoid surface exactly.
Not easy to do for the average fabricator.
In the beginning we used an NC punch to make all the slide
throttle parts. The flanges and all plates were punched out
square along with all the bolt holes. 3/16th thick with a 2 inch
hole was at the limits of the NC punch. The intent was to
mass produce the parts and keep the cost down.
If the tubes are cut first with the flange welded on them then
both flanges must be aligned so the holes in the flanges fit
the back plate of the slide throttle and the cut on the end
of the tube fits both trochoid surfaces. Are you going to
heat both rotor housings, cool the tubes and press fit
both tubes in simultaneously? Good luck.
That is why I used a slip fit for the tubes with square ends.
We placed both rotor housings side by side, inserted the tubes
with the flanges welded to them and bolted up the slide
throttle back plate to align the holes in the flanges
with the slide throttle back plate. The exact angular
position of the tubes was then marked on each rotor
housing. The back plate unbolted and the tubes bonded
in.
Think it through to final assemble. Perhaps you can
make a change in the design of the slide throttle that
can accommodate press fits with this alignment problem.
Sorry I did not explain all this stuff again when
the subject came up again. I assumed everybody had this
in their mind when I explained all this stuff way back when.
I'll dig it up. I will also add it to:
http://www.rotaryeng.net/fund-of-intake.txt
Paul Lamar ...No rotor no motor.
Paul & Doug ,
Ye Gads - what have I started, I was only trying to be helpful, as Doug is
planning some serious long distance flying and I didn't want to see him
POSSIBLY stuck in a strange country with a POSSIBLE leak of this kind.
Paul you are definitely right, this is much more than the average builder
can accomplish and indeed it may be terribly overkill.
However Doug has the capacity and the desire to try this method and I
couldn't think of anyone better to be able to accomplish it.
I was just looking at the outer housing and it's mighty thin perhaps only
4mm around some of the cast depressions - there may not be enough room for a
outer taper even a small one. Paul's suggested method of welding this may be
the answer but as Paul also suggested, there is a concern with warping. I
think the answer here is to have the outer tube tig welded ( very slowly,
i.e. a bit at a time). I am only thinking out loud here guys, so until I get
some more answers from my welder expert, I will leave it there.
My apologies - we're all trying our best!
George (down under)
--------------------------------------------
There is no question in my mind that this will NOT fail
in a mechanical sense. Therefore welding it won't help.
Yes you might someday develop a pin
hole leak but that is not catastrophic. You will just wonder
where the coolant is going. Worst case you don't have a coolant
level sensor installed and your engine starts over heating.
If I were flying anything for five hours over water short
of an airliner I would be very nervous. In that case I would have
a couple of gallons of spare coolant I could high pressure
pump into the engine a little at a time :)
Using the technique and tools I just outlined you could fix it
anywhere. Carry some spare JB Weld.
Paul Lamar ...No rotor no motor.
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