REFLECTOR: Fitting a New Nose Gear Bumper

[Mark Magee]

Hi Brian,
Yes I used urethane, can't remember the durometer of the block I bought. I
discussed the durometer of my urethane block with Jorge Bujanda and his
son, an engineer, reviewed calculations on the durometer I purchased and
found it to be harder than the 'rubber' used on the OEM unit Jorge used. I
went experimental and put considerable time into my working around Jorge's
well thought out and working solution, for at the time the prime vendor was
out of stock. I went to plan 'E' and found the block of urethane on EBay
for about $8.00 shipped and went 'Experimental/Jiggy' on the project. I'm
very pleased with the results, I don't see ever having to mess with that
bumper in my lifetime. Urethane is fabulously durable material, and a close
cousin to polyvinyl, a product know to be durable and long living.
I would recommend to anyone to use Jorge's solution as it is a known
quantity and working. My urethane bushing I believe to be a final solution
for me, but in my jigginess to get it done, (did I tell you folks I have 5
kids....) I took few pictures, have less data and only know my research
from the time worked. Jorge on the other hand was meticulous in documenting
is methodology and procedures and parts list, and therefore much more
repeatable for the group.
If you want to be experimental, you can probably find a block of urethane
on EBay for 1/10th the cost of Jorge's recommended bumper, you can cut with
a circular saw or hacksaw to fit and get a very good result. (Make
allowances for the change in durometer from Jorge's) You will however be
forced to boldly go where no man has gone before.
Except me. And I can't remember what I did exactly.
Works great... :)

Mark B. Magee
N34XL XLFG 300HP 80HRS
Brady TX USA


On Sat, Mar 10, 2012 at 10:07 AM, Brian Michalk <michalk at awpi.com> wrote:

> From the manual, I see that the drill location for the nose gear bolt is
> 2-1/8" aft of the canard bulkhead.
> What is the diameter of the strut?  Perhaps someone could measure their
> strut-to-CB distance for me?
>
> If I get a rubber block that is too soft, the strut will impact the canard
> bulkhead.  If I get one that is too hard, what happens?  Will the strut
> break on landing?  I have the equations to calculate the hardness needed,
> but I don't know what the desired deflection is.  Maybe I'm over
> engineering this, and the original engineering was just a SWAG anyway?
>
> Someone mentioned using a block of urethane.  That would seem to be a very
> hard material.
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