More Detail on Making Wheel Pants.

In the Quickie Aircraft plans, they have you make the wheel pants as a couple of straight-sided items, as seen her in Paul Fisher's beaut.

Air doesn't like to flow in a straight line around an object. There has been a lot of work done on pressure recovery wheel pants, and I thought it would be a good idea to take a clue from the guys working in this area.

So, the problem becomes, how to make a pressure recovery type pant with our little birds that use the pant itself to support the weight of the aircraft?  For the shape, I went to a set of RV-7 wheel pants and tried to emulate that shape. The way I approached it, was to build the interior of the plant per QAC plans. That way I knew it'd be structurally sound.  Once the slab sides are complete, I would build up the outside of the pant for the improved aerodynamics.  This would be a great place to use a wind tunnel and scale models, but unfortunately, that's not my bailiwick.

Again, I started out making the regular wheel pant structure, including the brakes and axle hard points.  I then fitted the wheel in place.  The brake calipers will be buried in the foam for the time being.

Next, using two part expandable foam, I glue Styrofoam scraps all over the wheel pant, giving it a slightly unaerodynamic shape. The idea is to build up enough for carving.

Now using a couple of templates as a guide, I get out my trusty Milwaukee Sawzall and start whittling away at it. I try to go slow and slice off a little at a time. Just like carving a turkey.  Keep your broom and trash can handy.

Here are a couple of videos showing more about my Sawszall art carving methods.

Part 1

After flipping the canard onto it's back, here is Part 2.

Starting the de-bugging

Now that I proved that it can fly, I need to get after all the squawks. Right now, the main issues are engine heat and power. Yesterday I went out and:

1. Adjusted elevator push rod for better roll trim.
2. Significantly opened up the path for cowling discharge air.
3. Discovered air leak around #2 cylinder. Will repair after next test flight.
4. Took care of fuel line chafing on cowl.
5. Plumbed in an airspeed indicator to measure cowling pressure differential.
6. Hooked up mixture meter so I can observe it in flight. I will continually be checking the fuel/air ration to fine tune the EC3 mixture mapping.
   

It started raining so I didn't fly.

Regarding item # 5 above. There are a lot of factors about engine cooling and there are several great articles out there if you are willing to search for them.

One of the fundamental things to check for is to make sure that you have an adequate pressure differential between the top of the engine, compared to the bottom of the engine. The engineers like to refer to this as inches of water, as seen in a manometer. Let's say you had no baffling at all. In that case there would be zero pressure differential and zero inches of water.

Lycoming wants to see between 5 1/2 & 6 1/2 inches of water. Since rigging up a manometer can be cumbersome, there is an easier way, using an airspeed indicator. I had an old one laying around so I hooked it up kind of like this (scroll down a bit).

If I don't have enough pressure differential, that should be addressed first. But, if there is enough difference, then I need to go after different things like controlling air flow around a specific component, but first things first.

So looking at the table below, I will be hoping to get about 110 mph on the indicator.

MPH	KNOTS	IN. of H2O	#/IN2
30	26.1	.44	.016
40	34.8	.79	.028
50	43.5	1.23	.044
60	52.2	1.77	.064
70	60.9	2.41	.087
80	69.6	3.15	.114
90	78.3	3.99	.144
100	87.0	4.92	.178
110	95.7	5.95	.215
120	104.3	7.09	.2558

I'll report my results later.