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Here's how I built a couple of props. The first one was good right out of the box--credit beginner's luck. The second one which I will discuss here took a lot of adjusting; you might find it interesting. At the outset, I will admit that it's easier to just buy a prop but what fun is that! There are probably easier ways to draw prop blades with a 3D CAD program but this is was my method.
1. The first thing is to decide what length and pitch to build. I kept a list of props I read about that a people were using with a given HP and speed range and put them on a spreadsheet. (pic 1) Comparing pitch is tricky because a prop builder might be quoting the pitch of the flat side or the pitch of the prop's chord line. There can be several degrees difference. I just assumed that every pitch was quoted at the chord line.
2. Pitch is quoted in inches at the 75% station. It is the geometric distance a prop with no slippage will advance forward in one rotation. However, a builder must know the chord pitch angle. My spreadsheet converted pitch-inches into a pitch angle. I chose 26.8° chord pitch angle for my 180 hp engine and a 67“ length. From some previous experimenting, I believe length is not too critical. Pitch and tip thinness make a big difference.
3. I used six nice maple boards, 3/4” thick, so the hub thickness would be 4.5”. I scraped them as recommended to open the pores and glued them together with Weldwood Plastic Resin glue, rolling glue on both surfaces and flipping the growth rings for each board, and clamped them tight for a couple of days. (pic 2) The Weldwood product was recommended because it has a more generous working time than Resorcinol.
This is an original, unstarted kit from Quickie Aircraft Corporation.
Included are fuselage shells, a smoke-tinted canopy, metal parts, original plans, and misc hardware. The metal parts are the find here, which have been gently bead blasted and oiled to prevent rust.
The kit can be used towards building a Q2 or Q200 (same fuselage and most metal parts).
Will crate and ship to your location at cost.
Asking $3,250 and proceeds benefit the Canard Zone and the Quickie Builders Association. Also listed on Barnstormers.
Marc Zeitlin posted a post in a topic,The only "fix" for a wing attach fitting corrosion issue is to completely disassemble and remove the metal parts, ensure that the composite spar is sound and wasn't damaged in the process of the original metal fitting installation, and then fabricate new fittings, protect them with alodining and appropriate coatings and then re-install everything with wet hardware. If you don't know what ALL of that means and how to do it, you're not in any position to do the work.
As I've stated numerous times before, I believe that it all could be done in about 40 - 80 hours of work, assuming that the underlying composite spar is in good shape.
As you surmise, there are many things that could bite you - the composite spar could be damaged, you might damage something in the removal of the corroded metal, or you might have trouble getting all the re-fabricated pieces to align and fit together correctly upon re-assembly. Paying someone $4k - $8k to do this work, with no guarantee of success, seems like a risky path to me.
VE's change hands fairly regularly, and they don't fall out of the sky regularly, but there HAVE been at least 4 known instances, in around 2K Variezes, of corroded wing attach fittings. Who knows how many are corroded and haven't been discovered? Nobody. I most certainly would never buy one that had any visible corrosion anywhere on the wing attach fittings.
See the picture below for a corroded fitting example - the visible portion, near the hand, is fairly decent looking - you wouldn't necessarily expect that the non-visible portion has severe interlaminar corrosion that has removed over 1/3 of the thickness of the material and damaged the rest.
Kent Ashton posted a post in a topic,Saw this oil cooler door idea (pic 1) on a FB page but I don't like it. The chap has an ingenious linkage to open and close the slots in flight but the problem is that when full open, half the cooler is blocked by the apparatus and even when open, the slots create drag on the air flow. In hot weather, you will want the whole cooler working.
I have a pic of a cooler using louvers by Marc Z. that is a better idea but it might be copyrighted so you will have to imagine it. :-)
I did not give this enough thought when building the Cozy. Eventually I arrived at this slider (pics 2,3) which is satisfactory but not in-flight adjustable. With experience, I know about where to set it. This time of year (Nov), it covers about 2/3rds of the cooler. In the winter it will block the entire cooler. Doing it again, I would offset the cooler which might have given the space for a cable-operated slider.