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Cozy MKIV - Sixth Flight Test

Date: August 14th, 2002

So the sixth flight was supposed to be descent cooling tests. After having done the climb tests, and since I park the plane at 350 ft. MSL (0 AGL) and I had to come down, I felt like I had enough information from the previous 5 flights regarding cooling. The basic idea according to AC90-89A is to figure out what RPM's to use during a descent to avoid shock cooling. Without starting a religious war about shock cooling, let me just state that I don't believe in it - old wives's tale, as far as I'm concerned. That being said, just to be safe, I figure I'll make my descents with 2000 RPM - that seems to keep the CHT's in the mid 200's.

Anyway, I was going to do climb rate / climb angle tests, but it was so dang hot today (Wednesday) that I didn't want to overheat the oil temps, which have been running a bit high. I decided to embark on the first "cross country", keep the power levels up a bit for engine break in, and test a few things on the way.

Before leaving, I finished the installation of the "Strong" pitch trim system [as an aside, this is a very nice installation - it took about 6 hours total to retrofit - it would probably be about 3 - 4 hours in a virgin installation]. There are a couple of changes that I would make to the system, but none are serious or large scale. I would use (and I fabbed) 2 CS201 spacers, rather than the tygon tubing, and I put an AN970-4 washer on the outside of BOTH ball joints (the stock MM4 AND the pitch trim one). This leaves room for the joints to move, and keeps anything from sliding off the bolt. Pretty minor change......

Anyway, to try to deal with the roll trim issue, I inserted one thin washer under the right lower distal bolt, which lowered the incidence angle of the right wing by about 0.3 degrees. It actually didn't take as long as I thought to effect this change, and if I had had an assistant, it would have been a lot faster.

I also fabricated a transfer pump from a generic fuel pump and switch that I bought at the auto parts store (yes, I know, I probably could have found one at a junkyard for $5, but I'm just not in scrounge mode right now). This allows me to tilt the plane backward, replace the wing drain with a 1/8" NPT fitting for tubing, tilt it forward on it's nose, and pump fuel out of one tank and into the other. I used this to drain 5 gallons out of the right tank and into the left one, and I then filled the right tank to the bottom of the gas cap neck to calibrate Vance's fuel sight levels and to find out the capacity. Right tank - 29+ gallons. Probably could have put in 30, but I was being cautious.

So after all that futzing around, I tightened everything up, did a complete preflight, and launched. I've flown one time in weather as crappy as this - on my long cross-country, back in 1975. It was 5 miles in haze with nothing that even remotely resembled a horizon. The air was 100 deg. F on the ground, 80 deg F at 3500 ft., and even at 6500 ft. it was still 70 deg F. Ugly, ugly, ugly - like flying through cream of mushroom soup.

However, I did verify that the pitch trim system works, and can trim the plane from 80 mph (didn't try any slower) to at least 160 mph, and there's no reason to think it can't go all the way to the top -). I also verified that changing the wing incidence angle by 0.3 degrees got rid of about 1/2 the roll trim problem. Vance was right - the bolt holes howl like mad if you leave them uncovered -). Took me a while to figure out what the heck had gone wrong with my headset.

All my previous flights (all five of them) had been conducted at about 1515 lb. This flight, I took off with an extra 20 gallons of fuel (120 lb) and an extra 20 lb. of ballast in the front seat (I've got a pretty eclectic party of ballast - 30 lb of lead in an old epoxy can, 23 lb. of my first dead battery, and 20 lb. in a 2.5 gallon water jug. I bought 10 2.5 gallon containers of water to use as ballast for higher weight testing - I figure we can always drink it, and it's pretty cheap and heavy). So this flight started at 1655 lb. Even with a density altitude of 2500 ft. at takeoff, I didn't really notice any difference in takeoff roll length.

I also tested the Navaid auto pilot - very nice. I don't have the "porcine" adapter for the Garmin 195 GPS yet, so I could only use it in wing leveler mode, but it worked very well. Hunted a little bit if it was bumpy, but in smooth air I didn't know it was on.

Took a lunch break in Pittsfield (PSF) and then headed off to Windham, CT (IJD). Took a break in the air conditioning there, added a quart of oil, and headed back to FIT.

I needed to keep my speed to 150 mph (power levels below 2400 RPM) or below in order to keep the oil temps down below 230 deg F. I'm going to have to fabricate a small air scoop and duct to feed the oil cooler directly - the oil temps are just too high (although the CHT's are fine).

When I returned, I removed one thin washer from the left lower distal bolt to increase the left wing incidence by about 0.3 degrees. This should finish off the roll trim issue. I transferred all the fuel into the right tank so I can eventually test the capacity of the left.

This was rather rambling and not exactly formalized testing, but I did verify the workings of a bunch of stuff, along with determining about how much I had to change the wings to get the roll correct.

So, for the next flight, accelerated stalls (up to 45 degree bank angle to start) and/or climb tests.

You can read the Flight Test Protocol (such as it is) for Flight 6.

End Date: August 14th, 2002


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