Posted Monday, April 13, 2009 @ 11:44 PM
Well, after a couple of years of diversions and distractions, I have started back in earnest on the rebuild of RF4D N2188. I acquired this aircraft from Collin Gyenes about 3 years ago and decided to do a complete firewall forward upgrade -- mostly because nothing much was really usable up front, and because I wanted to add an electrical system, starter, radio, and a transponder. I decided to go with a new Great Plains 1600cc with the Diehl case because the Diehl case could be fit into the space between the engine and firewall without adding bumps to the front of the cowl required if putting a starter and gear ring on the prop, and a belted generator up front.
Going to 1600cc was not to try to get more speed. Basically 1600cc is the smallest you can get new, and I could use more takeoff performance since my home strip has tall trees at both ends.
The two big issues that arose were that the 1" extra width of the new engine would not fit in the old cowl, and the Great Plains prop hub stuck out 2" further that the stock hub causing more problems fitting the cowl. I also did not want to modify the look of the aircraft if at all possible.
Collin came to the rescue on both accounts -- he had a 1600cc crank machined (and deep drilled) for the stock prop hub, and he acquired a new cowl from Eugenio that was made to fit the 1600cc engine. I am using Collin's cowl for fitting and we are looking to get more cowls into the US.
I am also using an AeroCarb, and this requires a custom intake manifold for the dual-port heads, and to fit around the Diehl case. I also designed (with the help of Paul Jackson) and built a new engine mount system for the Diehl case that closely mimics the old mount. .
Another planned rework is the canopy. Collin and I are working with Todd's Canopies to create RF4 canopies with a little more headroom. Yes, it will bump up an inch above the line of the turtledeck, but we think it will look fine and add a huge amount of comfort for tall folks.
So, after the hiatus, I was glad to (re)discover that a lot of the engineering had been worked out and that it is now really just a matter of execution.
Here are some pics of current status:
Engine and Diehl case fitted. Mocking up AeroCarb and intake system. I may need to put a small bump on the bottom of the cowl for the air cleaner (unless I can find a smaller one with an offset that fits the AeroCarb). This could also become a great ram-air induction with some work. But it would need a real carb heat system, as these carbs can still ice up because of the temp drop from fuel vaporization.
The engine, Diehl case and new engine mounts from higher view. The wood blocks are for cowl spacing.
...with the top of the new cowl set in place.
The whole cowl taped in place to check fit. The cowl has a large cowl flap built into the bottom for better cooling. Collin is putting up a post asking about interest in getting more of these cowls to the US to reduce shipping costs.
Jig for making the intake manifold lower tube.
Cutting holes in intake manifold tubing.
This is the "Y" at the bottom of the intake manifold.
The lower tube almost ready for welding.
This is a Photoshopped image that is probably what the new canopy will look like. Once we get a design worked out, Todd can make them for a very reasonable cost. We will post details as this moves along.
Comments and advice welcome. Will post more pics as things progress (quickly I hope).
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Dann Parks • RF4D #4051 N2188 • now flying!
Pictures at: https://picasaweb.google.com/111628310900713778468/RF4D_N2188?noredirect=1
