Mail Sack, 1/21/13, Getting started and various topics.

Builders,

Here is a sample of from the mail:

A letter From Jeff Moores, Merlin/Corvair builder and flyer from Newfoundland Canada. Jeffs story of building and flying is in this link:

“Hi William, I flew my Corvair/Merlin today from our frozen pond on Full lotus floats. Everything worked perfectly. The temperature here today was -10C so I preheated the engine for an hour with the heat gun and scat tubing setup. It started immediately as usual. Taxi on the snow was easy as there is lots of power available only needed about 1200 RPM to get it moving. The takeoff run was only about half the run required on water. From the pond to the hangar is uphill, but I was easily able to taxi right up to the door!!! I’m so pleased! -Jeff “

On the topic of the “Getting Started” series, Pietenpol builder/flyer Gary Boothe writes:

“I love this stuff! Even though I have one plane and engine under my belt (engine was closed up 8 years ago!), this is a great review as I prepare for #2. I now have 3 cores, all able to make use of one of the options…Gary”

 (The story of Garys plane is here: New Pietenpol, Gary Boothe, Cool, Calif.)

On the topic of the “Getting Started” series, Builder Robert Sceppa writes:

“I have just had my crank reground, safety shaft made and its in the shop for nitriding, ala Pramod. The front gear was removed before it is nitrided. Its an 8409 crank and I suppose I have to have that gear put back on, but its no problem I have some one that can do it.”

Robert, sounds like you are working on an ‘Allan Able’ format engine. It is good to have resources and skills available at that level-ww

On the topic of the “Getting Started” series, 750 builder and CC#24 grad Charlie Redditt writes:

“I love the numbering system, and since you obviously don’t have enough to do ;-) I might suggest an accompanying list of specialized tools (like the gear puller you mention above) that go along with each group. I’m sure that such would be mentioned in any instructions or videos for each group, but a tool list is really useful for tyros like myself.”

On the topic of the “Getting Started” series, Builder Dan Branstrom writes:

“This is an obscure point, but I think I remember asking about the original GM nitrided cranks, because a bunch of original Corvair engine parts still in the cosmoline were sold from the cache of a former mechanic in San Diego, and I met someone who had scored one at a Chapter 1 open house. As I remember your comment at the time was that the ion nitriding used today was superior to the nitriding used by GM when they manufactured them. Of course, since it’s a new crank, and a 5th bearing would be added, I imagine that the difference in nitriding wouldn’t make any difference.-Dan”

Dan either of the two processes, done correctly, work well in our application. Cranks from GM, Moldex, and Weseman’s 8409 process are Gas nitrided. Cranks that are from Nitron and Wesemans new cranks are Ion nitrided.  Nitriding by either method involves keeping the crank at very elevated temperatures for many hours. After this process, the cranks need to be checked for straightness. A good number of them will require the work of a skilled crank shop with either a brass drift or a press. After either  of these operations, that spot needs to be rechecked with a magnaflux test. Moldex does this when processing cranks. Dan’s 8409 process has an additional step: the cranks are all stress relieved for many hours in an oven before any work is done to them. When they are later gas nitrided, they never warp nor require straightening. The process is a little more expensive because of the two heat treatment cycles. Where many people speak of nitriding ‘warping’ cranks, in reality the heat of it is just stress relieving them. If this is done first in a separate operation, the nitriding, by either method, has no detrimental effect on straightness.-ww

About William Wynne
I have been continuously building, testing and flying Corvair engines since 1989. Information, parts and components that we developed and tested are now flying on several hundred Corvair powered aircraft. I earned a Bachelor of Science in Professional Aeronautics and an A&P license from Embry-Riddle Aeronautical University, and have a proven 20 year track record of effectively teaching homebuilders how to create and fly their own Corvair powered planes. Much of this is chronicled at www.FlyCorvair.com and in more than 50 magazine articles.

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