Dan Ruggirello wrote:

As Paul also implied, not 15 lbs off the housing alone.  By gearbox, I

mean

the full reduction unit assembly.  Anyone know what the current full
assembly weight is for the RD1-B with mounting plate etc etc.?  57 lbs

or

so?  (If so, we are talking about a 25% weight reduction, right?)

SNIP<<

Understood, but my main point was to be realistic about weight,  weight
reduction and how to achieve it.
First step is to start with accurate data.  I'm not sure where many of the
numbers I see on this and other lists come from but many of them erroneous.

I'll get a precise number for the RD-1B and post it later but the RD-1A
drive is 42 pounds and the -B version is about 1.5 pounds heavier.  The only
thing that might have been missing in these figures was bolts for the
adapter plate (2 - 3 pounds at the most).  See, we have already reduced the
weight of the drive by at least 12 pounds just by talking about it!  : )

I reduced the weight of the RD-1B on my plane by about 3.5 pounds with very
little effort, mainly trimming excess metal from the adapter plate.  Total
time to do this was less than 2 hours and did not reqire any special skills.
I'll be posting instructions on how to do this on my website.

 Using machine tools on the existing castings and other parts, there are
probably 2 - 3 more pounds to remove and I will probably make this an extra
cost option in the future.  After that things would get a lot more
expensive.

If price were no object, the weight could be dropped 5 - 6 more pounds.
Would anyone be willing to spend $2000 more for a drive to drop 5 - 6 more
pounds?
Weight can be reduced elsewhere on the plane for a lot less.   I'm using
optional aluminum landing gear on my RV-8 at a cost of $700 increase in
price, but that gets me a whopping 15 pound weight reduction.  Spending
$1500 on an aluminum Racing Beat sidehousing  saves about the same amount.
Buying one of those new spiral cell batteries saves about 12 pounds over a
standard aircraft battery, and that's less than $100.

Tracy Crook
tcrook@rotaryaviation.com
www.rotaryaviation.com

Don't give me that. I offered to do a UBH casting pattern for you for free and 
you ignored me :) This would get the total weight of the housing down to about 11
pounds and short light weight bolts could be used to bolt it to the engine.
Also it would look ten times more professional. Don't underestimate that point.
No way would a UBH casting and hollow output shaft add $2000 to the cost 
of the PSRU if done right. If you believe that you are deluding
yourself because somebody will figure out how to do it at the same 
or lower cost. Here is a bit of subtle biz advice from an old businessman: 
You are vulnerable on these points Tracy. It is easy to get lulled into
a state of complacency but believe me things can change in an instant.
Unless you continue to improve your product to the best of your ability
and imagination you could become obsolete overnight. Been there and done that.
So too was Henry Ford with the Model T.

Here is the latest iteration on the hollow 4130 steel hydroformed output shaft.
The low stress prop flange and prop pilot are aluminum and slip over the steel prop
drive pins.

Paul Lamar
 
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