Hey Paul and group,
I know Tony in Las Vegas that was offering the Titanium bolts for
the
13B. His email system is terrible as he has to many filters on there
to
get the emails. He asked me to ask you the following.
The Studs look good. I noticed he threaded the shafts a little too
far
but that could be adjusted no problem. You said the Aussies were
using
larger studs, how much larger?
10 mm (.3937) actually not 3/8th.
Not sure could be up to half inch.
Eighteen 1/2 inch studs are going to weigh .0589 pounds per inch.
About 13 pounds. Ti would be about 7 pounds.
Density = .17 pound per cubic inch. Steel = .3 pounds per cubic inch.
The current studs are 3/8 then cold rolled threads to fatten the
threads up.
Are the Aussies using 7/16 shafts and what is the benefit to doing
that?
High power engines tend to twist and break the housings. There are
only
two hollow dowel pins to prevent this. What the Aussis do is drill and
ream
all 18 stud holes for close fitting studs that prevent this twisting
from happening.
Necessary for a 800 HP turbo two rotor running on alcohol and NOS.
I think to reach a larger group of people, the standard 3/8 shaft will
require
minimal changes and they can just drop in. As far as elastic coef. I
dont have an
answer tothat but I dont think that our relative low RPM scenarios are
non taxing on
these studs. There is a huge weight savings on these things. Cost is
as pretty as the
studs.. Your input will help him out. I told him that at least 30 sets
would be
required for an initial run. What was your initial run on items like
the manifolds?
Thanks,
Doug Mueller
RX-6 13BT
N900DM
Boulder City, NV
Paul, Machinery's Handbook says: Steel COE 6.3 x 10^-6,
Aluminum (grade not specified) 1.2 x 10^-5,
Titanium 4.9 x 10^-6. All per unit per degree F
Bill Jepson
The COE is a little less than steel which is not ideal when it comes
to wide
temp changes. That is why the rotor housings shrink permanently when
the engine
is overheated.
Stiffness is half of steel so that is in Ti's favor in this regard
out weighing the lower COE. In other words they will stretch a bit
more
when the aluminum rotor housing expands due to overheating.
All and all it looks good. Make sure you constrain them from vibrating
with RTV as the lower stiffness means they will vibrate at a lower
frequency.
The remaining unknown is the fatigue characteristics of titanium.
Paul Lamar
I think the main advantage might be the lower modulas of elasticity
reducing
the chance of permanently shrinking your rotor housings if you severely
overheat
the engine by running it without coolant.
Paul Lamar
Vance W Jaqua wrote:
Titanium is notorious for notch sensitivity - For bolts, both titanium and
aluminum are cosidered
high risk desperation -Vance
Thanks Vance. I had no experience with it. OK folks bad idea. back to the
drawing board. Not worth the risk and expense.
Paul Lamar
Vance,That might be the case with Ti but lets be realistic if the Ti stud is not
compromised during installation is notch sensitivity still a concern? Does the
flexing of housings in our installation cause notching? Would exceeding the COE
cause it? I will test it but I think it wont. just my 2 cents worth. On the other
hand the point that Paul brought up about housings and shrinkage is a major
concern, but then again if my engine is overheated in flight, that is the least of
my problems at that point. I would be looking for a prime piece of realestate.
Doug
I think he is referring to the root of the thread. That is where the steel studs
break when they vibrate.
Paul Lamar
Hi Paul thanks for the comment. I am not sure that is the case with rolled threads. I
would agree with it if it was cut threads.
Doug
Probably what is required is a bit of testing on the ground.
If he can find a Mazda rotary road racer somewhere that might be a good test.
Paul Lamar
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