12.3.5 Propeller

This entry is part 31 of 50 in the series 12 - Engine / Propeller

About 3 years ago, I ran across an ad for an MT Prop… at a real good price. From a distributor. The story was that the prop was ordered but due to a miscommunication, a four-blade prop was what the buyer wanted but a three-blade is what they got.  Either way, the (new, never used) three-blade was up for sale. It was way too early for a prop, but I got it anyway. And for three years, it’s been sitting around, generally getting in the way. Now it’s on the engine… getting in the way.

Getting the cowling on is now impossible though. The opening for the prop was never trimmed. That’s intentional so that it could be done once the prop was on and it could be trimmed as close to the prop spinner as possible. So, somehow, I have to figure out how much to cut off of the cowling without taking too much.

So I measured the distance from the prop flange (on the engine) to the front edge of the spinner.  Then I removed the prop and bolted on a piece of plywood cut so that it just fit inside the cowling.

Then I made a spacer that would give me a dimension to where the cowling would have to be cut.

Now I just mark the cowling (black ink shows up better on green tape than black carbon fiber) where it needs to be cut.

Then cut the cowling and install.

The cowling is still very difficult to get on though as a result of the way I’m doing the cooling plenum and NACA extensions. and it’s almost impossible to assure that the NACA extensions are sealing properly on the baffles.  I may have to come up with a two piece upper cowling to resolve that.

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