Test Flight

I elected to use the cool calm air of the following morning for the test flight, spending the remaining part of the day on some runway runs. The first thing I noticed, ...
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Test Flight By Harvey Mace, EAA 2740

Photo by Houston Walsh

"Macerschmitt", Harvey piloting

his is the story of the test flight T and results of subsequent flights of my homebuilt, Mace M-101 "Could Bee",

now tagged "Maeerschmitt",

first described in SPORT AVIATION

for December, 1959. I felt that this might be my only shot at building a plane, so from the outset, I was determined to design and build it completely on my own. This I did, with the sole exception of the paint job — George Pereira helped with that. The only "different" design idea about the Maeerschmitt was the wing-tip ailerons I built as conversation pieces —did they bring the conversation! Final assembly and weight and balance were completed on July 14, 1959. Bill Rysavy, our very cooperative FAA representative, nodded approval (he may have been shaking his head in dismay!) and we were cleared to leave Sacramento Municipal Airport on the only remaining clear runway (houses again!) to proceed to an abandoned auxiliary field. I elected to use the cool calm air of the following morning for the test flight, spending the remaining part of the day on some runway runs. The first thing I noticed, taxiing around, was the blessing of the sliding canopy — great! The second was

the slow response of my homemade tail wheel fork (the wheel was salvaged from a scrap pile). The spring was too stiff — like a board. Also, the brakes worked, but not with enough leverage; as a homebuilder, how would you calculate the necessary leverage in mating twin Cessna master cylinders with J-3 expanders? Anyway, there was nothing to keep us from flying, so I proceeded to 4000 ft. of runway the tower gave me to play with. With a very flat prop, 76-44, she accelerated smartly, and in short order was up! It's pretty hard to explain the exhilaration of being airborne in your own creation. I tested each of the controls in order, rudder and elevators being just right, the ailerons rocked the wings a little slowly, but worked; then I greased her back down on the runway, all in less than 4000 ft. — a huge success! Everything went very smoothly— the calm before the storm I guess. The return run I decided to be just

20

MARCH

1960

be so low, I decided to keep an eye

on the airspeed indicator and check it while hauling it off threepoint, a tough job in a strange hot airplane. She accelerated fast again, and as speed reached 63 mph lift-off was imminent and I had to quit looking and fly. I can safely say it got off

well under 70, very respectable. At the slower flying speed, and gustier air, it wasn't long 'til a gust

picked the upwind wing up and I corrected, then some more, then while seriously considering putting

her down, she leveled off. I've had ATC'd airplanes act like that in gusts, so we proceeded on. Then another gust and correction without results. I even took the time at this point to look at one aileron and put it in what appeared to be a good nonstalled angle, without results. Then the wings rocked up level and back

again, in spite of, not because of, my stick action. Now it was clear,

whizzed along, slower than before,

even to a hardhead, that I just didn't

then chopped the throttle and dropped the tail, and very unexpectedly took off again! She was getting off slower than we thought she would. We smoothed her back

had had enough. I've lost tail wheel tires before without ill effects, but this one must have jammed crossways, because in spite of determined opposition from yours truly, the

Photo by Houston Walsh

airplane had proven very docile, so I taxiied out for another runway run. Since the take-off speed seemed to

a fast taxi since I was heading towards the operating runway. We

on again and at this moment the scrap pile tail wheel tire decided it

Harvey Mace and son Kip

By this time a little right hand cross wind had sprung up, but the

have adequate aileron control, so I made a hasty one wheel landing which left the up-wind wing up. As

soon as the wheel was on the runway it began to have a keel effect and the wind blew the wing higher and higher. Now it was a race between slowing it down, with one brake, to drop down speed, against the wind getting a wing first. It worked out a tie. The wing just

touched, without damage, as it slowed

Maeerschmitt headed for the boondocks. It seemed a shame to have her stacked up from a little false economy. At the last instant the tire went the rest of the way and once more I had things under control. Back to the shop for a new tail

to drop down. The tip ailerons could have been made to work with a little more area, they worked at higher speeds, but we weren't in research and development for wing tip ailerons, so, while we were still ahead, we dismantled it

wheel!

and took it home to put conventional

Motor mount detail

wagglers on it. I thought it was a worthwhile experiment, after all, how many guys have gotten to fly wingtip ailerons, even for a little bit? I had looked ahead, away back, and had plans all laid out for conventionals, so it wasn't too tough a job. But the busy dusting season was upon us, and while I had it back in the shop I corrected all the other little ills. All this took another two months before we were ready for the runway runs again. This time it was apparent from the moment the wheels left the runway that we had all the aileron control we needed and enough left over for a couple of other airplanes. My redesigned tail wheel was working nicely and the brakes were better. It took only one more runway run to assure us that everything was ready for the following morning. I don't know how other guys take their test flights, but when I firstflight a job (I've first-flighted five different experimentals, slow ones and hot ones) I like everything right, particularly with hot ships. With them, besides being excited and interested, I'm scared. I won't fly without the odds in my favor. They have to have proper weight and balance, fuel flow checks, etc., and a calm cool morning for the first flight. Calm air is for being assured that any action will be the airplane, not the wind. Cool air, because it's more substantial to fly in, and gives the untried airplane a chance to prove

Instrument panel

Helen in the cockpit

Photos by Harvey Mace

I was so excited I forgot the carb heat was on 'til it was nearly ready to lift off, then about the time it lifted off I detected an exhaust note that shouldn't be there. In spite of getting full rpm it wasn't right, so I set her back down. Taxiing back

off. The "Macerschmitt" fairly leaped off the ground, and I found I had to throttle back over halfway to keep under 2500 rpm. I made no attempt to climb until I got past the point of no return, which looked like miles away. The thing that stands out

more after a good runup, maybe the carb heat had been the cause. No soap, it was the same again, back to the hangar. The people on the ground agreed that there was a slight popping. After everyone went home I went after the most obvious and easily checked possibility, the plugs. Sure enough, three of them turned up with silicon beads on them where I hadn't cleaned off the sand blasting sand well enough. A new set of plugs cured the popping and got 25 more rpm than it ever had, that paid off. Next morning, wolf had been cried too many times, I guess, and none of the flak-hole counters could be rousted out, leaving just the wife and three boys in the Clipper. This time I hoped to get past the point

off was the length of time it took to reach that point of no return! It did go by though, and things were functioning perfectly, in spite of the horribly flat prop. It was great for take-off and deceleration but too flat, even for a climb, half throttle easily taking it over the red line. The wife was having to push the Clipper

to the runway, I thought I'd try once

of no return on the runway quickly,

so there'd be no excuse to call it

in my mind the most about that take-

to stay with me at that, though.

We landed at our destination without incident. I let Helen make some runway runs and flew the pattern once more myself, but the prop was too far off for satisfaction so we called it a day. The next morning I mounted a borrowed 74-54 off a Tri-Pacer. This

was still too flat, but what a difference! It still got off snappy and climbed like a scalded cat. I could go to about two-thirds throttle withContinued on Page 22

Photo by Houston Walsh

itself without pushing the new cool-

ing setup too hard. Maybe you think all this caution is for the aged — you're right, I'm pushing 40 — but it's also backed up with the experience of what happens if you don't

Top view reveals sleek lines. Note tip ailerons, later modified to conventional type

do these things. Test flight morning dawned cool

and calm. All the people who insisted on being there were rousted

out, the wife was up in our Clipper, chase planeing, and I taxied out feeling at least as important as Scott

Crossfield. We were green lighted onto the runway and away we went. SPORT AVIATION

21

TEST FLIGHT... Continued out going over 2500 rpm. As to cruising speed, first I'd like to say a little about props here. In preparing this ship for flight, I was amazed at the number of people who were unfamiliar with this problem. First, if an engine is rated at 125 hp at 2600 rpm, that's only part of the story. It's at 2600 rpm and a known manifold pressure; yes, even with a fixed pitch prop (we'll overlook other fine details like temperature, etc.). Thusly, sticking any old prop on and turning 2600 isn't necessarily absorbing 125 hp. We know the propeller is changing horsepower to thrust. We know that airplane Y takes X amount of thrust to go 160 mph (if the airplane has 100 Ibs. drag at 160 mph, it will need 100 Ibs. thrust to do it). We also know, under certain conditions, one hp can produce 1 Ib. thrust. Therefore, hypothetically, our propeller will have to absorb 100 hp (X manifold pressure at X rpm for X engine) at cruising rpm to force the airplane through the air at 160 mph. Obviously then, a flat prop that is turning 2350 (cruise) at half throttle (greatly reduced manifold pressure) is not absorbing the necessary hp, therefore not producing the necessary thrust to go 160. Or, more simply for the layman, at 2350 rpm, a 44

It was going so well that, after a couple more flights, I put Helen in it, cautioned her once more about overshooting and sent her off in it. Her take-off run was very smooth, it gave a little wiggle after lift-off, not bad for her first time at real sensitive controls. She played around with it for about 40 minutes, then made a nice approach for the first of a couple of practice approach flybys. As she leveled off about 20 ft. over the runway, I could see she was getting too slow at a very awkward height, too low to keep an eye on the airspeed, too high to stall in. The thing that was fooling her was the extremely sloping nose I designed in for visibility. Her next time around, I erred. I motioned her to get lower, she saw me and was trying to figure out if I meant land, or what, and that's all the distraction it took. The "Macerschmitt" paid off about 10 ft. or 15 ft. up, the right wing dropped, and she had time to yaw some, too, and hit right wing down skidding to the left. The right gear retracted on impact, getting the borrowed prop in the process. Then

she rocked up on the left wheel and wing tip, skidding to a stop in a right turn. The wife wasn't hurt, fortunately. Maybe later we can get her to expound on the sensation of staring at one's hubby through the wreckage of his brand new homebuilt. At first it looked like a basket case, but on closer inspection it proved to be very superficial damage. I whipped her back in shape and the "Macerschmitt' is flying again. The dinged prop was shortened and repitched to 65 pitch, 65 in. diameter, which was a fair compromise prop, and would give

Photo by Harvey Mace

Conventional aileron now installed

inch pitch prop will only go 100 miles ahead in one hour (roughly), a 54 inch pitch 120 miles ahead, and about a 73 inch to go 160 mph. Actually

there is more to it than this, but at least it should explain why the "Macerschmitt" won't cruise much faster than a Tri-Pacer with the Tri-Pacer prop at 2350 rpm. But at least it

was enough prop to make a very enjoyable flying airplane out of it, and there ensued much picture taking the next two days. I'd like to brag here a little. Once past the aileron incident there was no further fiddling or adjusting to do to the ship. It was performing faultlessly, easily and without quirks. Everything was just as I hoped it

would be, except for verifying speed performance. 22

MARCH

1960

144 mph

without

slippage, at 2350 rpm. In actual practice, by stop watch, the "Macerschmitt" does 139 mph at 2350 now. I made the test flight, after repairs, from my place of business, a very rough 1700 ft. It gets off from there very well, getting to 1000 ft. from a standing start in under one minute (51 seconds, to be exact). It's still climbing 1000 ft./min. at 6000 ft. at normal climb power, and 650+/

min. at 11,000 ft. I haven't been

over 12,000 ft. since it's still doing so

well there I would probably need oxygen to reach ceiling. By way of acrobatics, I have only done barrel rolls, but these are done with great aplomb and no noticeable effort. The airplane is extremely stable, and flies hands off which was a big surprise to me. We've put our 75+ hours on it, and Bill Rysavy has lifted the restrictions. Best of

all, Helen has tried her hand again,

Photo by Mauno Salo

The "Macerschmitt"

and very successfully this time. Not too many gals have handled a 125 hp Goodyear racer, so she should feel quite proud. To sum things up, I feel the airplane is a real success. The accident was a blow, of course, but just one cf those things. By making a mistake, Helen learned a whale of a lot, so it wasn't all lost. As for the success of my innovations, the visibility aids I built in, low sloping nose and incidence in the wing were excellent for me, but, since they were a direct cause of Helen's misjudging, offers some doubt as to their worth. I personally know of two different dusters wrecked, one a washout, by more experienced pilots than Helen, from misjudging low sloping noses. The adjustable seat was excellent, as well as the sliding canopy. The variable incidence adjustment proved unnecessary. The adjustable stabilizer is needed in this airplane to compensate for our weight difference, but the direct quick acting control wasn't, though there is nothing wrong with it either. The 3.5 degree incidence was helping the landing and takeoff speed, but how detrimental it would be to higher speeds remains to be seen. It would be nicer to have had the airplane 100 Ibs. lighter, as it could have been, but this would have cost me more. Now on the next airplane I build— SPECIFICATIONS OF THE "MACERSCHMITT"

Wing span . . . . . . . . . . . . . 16 ft. 6 in. Length . . . . . . . . . . . . . . . . 17 ft. 9 in. Wing area . . . . . . . . . . . . . .65.5 sq. ft. Empty weight . . . . . . . . . . . . . .685 Ibs.

Gross weight . . . . . . . . . . . . . . 1 0 0 0 Ibs. Wing loading . . . . . . . 1 5 . 4 Ibs./sq. ft. Airfoil . . . . . . . . . . . . . . . . N A C A 0009 Propeller . . . . .65 in. dia/65 in. pitch Engine . . . . . . Lycoming 0-290, 125 hp Top speed, rated rpm . . . . . . 170 mph Cruising speed, 2450 rpm . . I S O mph Stalling speed . . . . . . . . . . . . . .80 mph Rate of climb. Sea level . . . . . . . . . . . .2000 ft./min.

At 12,000 ft. . . . . . . . .650+ ft./min.