by Max Karant
This article first appeared in the December 1948 issue of FLYING magazine. Max Karant was the assistant general manager and editorial director of AOPA. Because of this article, he is given credit for using the name "Mite" applied to the Mooney M-18 for the first time.
THIS is the first time I've ever strapped an airplane to my pants and flown away. The Mooney M-18 (I'd call it the Mite) is so tiny that you almost "strap it on" to fly it.
This is one of the most interesting little personal planes to be produced in recent years. The M-18 has a number of unusual features: a 25-h.p. automobile engine, belt-driven propeller, almost unbelievable operational economy, and a number of others I'll mention as I go along. It is a low-wing monoplane made of wood, fabric and metal, and has a manually retracting tricycle landing gear.
The power plant is a converted Crosley auto engine. In order to use it in a certificated plane, Mooney had to get a CAA type certificate on the converted engine, as well as on the airplane. He worked out the modifications, then got the Crosley company to incorporate them. on their production-line model. Result is that the engine now is officially known as the Mooney CC46M-2. Though Crosley delivers the modified engines to Mooney in Wichita, the Mooney people still must make a thorough examination and test of the entire power plant before it can be installed in a certificated plane.
|Cockpit of M-18 is not soundproofed and controls are out in open to keep cost of plane down. Plexiglas hatch slides on runners and can lock in three different positions. Gas tank is located back of pilot's head. Baggage compartment holds 20 pounds. In flight, the single-seater is extremely sensitive to controls.|
Originally, Mooney was considering using a Waukesha or Hercules power plant. Then he saw a Crosley engine developed to run electric generators for the Navy (Crosley later adapted it for his automobile). It more nearly fitted Mooney's requirements, so he started work on the conversion. The result appears to be a reliable, rugged little engine. I found just two things wrong with the engine in the airplane I flew: at about 2,000 r.p.m. it vibrated furiously; and it had an unusually strong tendency to ice up. The latter, of course, is the most dangerous characteristic and is due, Mooney tells me, to the fact that the engine uses a very small carburetor venturi which is liable to cause it to ice up quickly and frequently. It did with me - and if I hadn't already made a few landings, which convinced me I could land this little mite in a Victory garden. I'd have been pretty scared when the engine suddenly started to drop r.p.m.'s. I quickly pulled on full carburetor heat and pushed the throttle wide open. The engine slowly began to pick up and soon was running normally.
Mechanics will be interested in these specifications for the Crosley engine used in the Mooney plane: bore, 2.5 in.; stroke, 2.25 in.; displacement, 44 cu. in.; compression ratio, 8.2 to 1; dry weight (including generator), 101 pounds.
The engine delivers its maximum 25 h.p. at 3,900 r.p.m. The fixed-pitch wood propeller, however, is driven by four Goodyear belts which turn the propeller at half the engine speed. Your first suspicion, of course, is that the belts would be the most vulnerable part of the entire mechanism. Apparently they are just the opposite. Mooney started out by using a common variety of V-belt, which held up very well, but which developed an apparently incurable slippage. During those tests, Goodyear engineers had been working on a new type of belt which eliminated all the V-belt problems, including the slippage. This new belt is called a wedge belt, and has proved so good that there have been no signs of wear, slippage or deterioration in all the rigid tests that have been made of it.
So far as the plane's powerplant efficiency and safety are concerned, there has not been a single serious problem come up with the belts. In all the tests Mooney has run, only one belt actually failed. It was one of the old V-belts and it failed during a prolonged test at 6,000 r.p.m.; the Mooney engine never turns over 4,300 r.p.m., and uses only a maximum of 3,900 for take-off. Mooney's present plan is to set up an arbitrary 250-hour replacement period for all power plants that go out in these little planes. He's setting the figure at 250 hours just to see how this equipment wears in the hands of average users. He feels that 1,000-hour replacement will eventually be common. For the time being, though, he wants to take back each power plant unit after 250 hours, exchanging it for a new one that will be installed in the customer's plane. Mooney's main concern is to make a careful check on the lubrication of the propeller-drive bearings, the one thing that actually caused trouble in early tests.
For all its modification, the engine is quite heavy: four pounds per horsepower. Reason, of course, is that it is basically an automobile engine with few of the lightweight, though expensive, aircraft parts. The Tillotson carburetor is the same as that on the automobile engine. So are the ignition system, the spark plugs-even the liquid-cooling system, which carries 1.8 quarts of coolant (40 per cent Prestone or Zerex, the rest water; this mixture is used the year-round) .
Because the power plant unit is by far the heaviest part of this tiny plane, it contributes more than anything else to the plane's unsatisfactory take-off performance. The Mooney M-18 has been licensed with a power loading of 28 pounds per horsepower - considerably higher than any other personal plane I know of. That compares, for instance, with the Bonanzas power loading of just over 14 pounds per horsepower. After flying this airplane for more than an hour, I couldn't help think of the performance this excellent little airplane might have if it had a higher-horsepower aircraft engine which could be installed for the same weight. But the reason this hasn't been done is simply cost; while Mooney could probably double the horsepower for the weight, the cost would increase tremendously.
The fact remains, however, that the M-18 does have critical take-off performance. I don't recall ever having spent so much time getting a plane off the ground. A couple of times it took me over 15 seconds to get off of a macadam runway and into a 20 m.p.h. cross wind. Some of this was due to my inexperienced handling of the very sensitive controls. But even when the plane is flown by a company pilot it takes quite a while to get airborne. Factory specifications say the ship will get off in 600 feet. The CAA performance figures for the airplane taking off and climbing 50 feet, at the altitude and temperature at which I flew this airplane, call for a distance of nearly 2,400 feet.
And because this take-off performance is so critical, anything and everything affects it. There's a pronounced difference between a take-off from a hard-surfaced runway and from a grass field, with the grass slowing take-offs perceptibly. Despite the strong wind that blew during the time I was flying this airplane, I never timed a take-off at less than 15 seconds - which compares with a number of four-second take-offs I made with an 85-h.p. Taylorcraft in a 10-m.p.h. wind just two days earlier. . . . But I'm getting a little ahead of myself.
You can't very well get checked out in a one-place airplane. So you just climb in, a pilot shoves you the various controls, knobs and buttons, tells you how to use them, and that's that. The Mooney people wanted to make sure I knew how to operate the retractable landing gear, however, so a couple of men lifted the wings, put a sawhorse under each, one man held the tail down, and I was ready to try the gear a couple of times. This gear is retracted manually; there's no electric motor or hydraulic pump to help you. There's a counter-balancing weight somewhere in the mechanism which is supposed to make it easy for the pilot to retract the gear quickly after take-off.
So aside from getting a chance to work the gear a couple of times on the ground, you don't get a chance to feel out this airplane until you fly it. I was shown how to operate the simplified trimming device (very much like Mooney's Simpli-Fly system on the Culver V), the engine and flight controls, and then I was on my own.
The engine doesn't have a starter so I held the brakes while a man cranked the prop. The engine starts up with a roar and immediately starts running so fast you think you're over-revving it. But one look at the slow-turning prop is enough to remind you that the engine is supposed to sound that way.
While the engine warmed up, I fastened the safety belt and made myself comfortable in the tiny fabric-and-tubing seat. My shoulders touched each side of the cockpit and I had to use my right hand to operate the trimming device beside my left shoulder. The vertical throttle. handle is on the left side of the cockpit, just ahead of the trim handle (they interfere with each other once in a while, especially during landing approaches). The rudder pedals and toe brakes are conventional and are at the forward end of two small tunnels into which you slide your feet, one on each side of a large bulge that sticks up into the cockpit just ahead of the control stick. The retractable nose wheel fits into that bulge.
The control stick is small and fairly short. Both it and the rudders are very easy and sensitive to operate. The plane is easily steered on the ground by gentle use of the brakes.
The entire cockpit interior is pretty bare. There is no soundproofing. All the tubing and controls stick out in the open and only the minimum required instruments are on the panel. The Plexiglas hatch slides on runners and can be locked in any one of three positions at the discretion of the pilot. At about 2,000 engine r.p.m. the hatch on the airplane I flew set up such a racket I instinctively ducked; the whole airplane vibrated at that power. But once you get the engine I running a little faster, the vibration settles back to normal and is much less.
The gas tank is behind your head and holds 7 gallons and 6 pints of 80 octane fuel. There's a glass-tube float gauge just behind your head, on the front end of the tank. The tiny baggage compartment is back there too; it holds a maximum of 20 pounds. The fuel cut-off valve is on the left wall of the cockpit, just ahead of the throttle handle. Mooney has rigged it rather ingeniously so that the valve - if it's accidentally left off - is bumped into the "on" position by the throttle when it is pushed to the wide-open position.
Once you've checked all these things you're ready for take-off. Because you've kept the carburetor heat on all during the warm-up (it's standard procedure), you must be especially sure that you push it off before take-off. Other than that, all you do is shove the handle up against the instrument panel and steer the plane down the runway with the rudder. You must be especially careful not to leave your toes accidentally on the brakes. Best thing is to rest your heels on the floor, steering lightly with the bottom of the rudder pedals.
Considering the racket the engine makes when it's wide open, you get the impression this little airplane is all set to leap high into the air as soon as you open the throttle. Instead, it just starts rolling, picking up speed slowly. After a while I started pulling the nose wheel off with the air speed reading about 40 m.p.h. Pretty soon the back wheels came off too, and I quickly dipped the nose to pick up whatever additional speed I could get so as to accelerate the climb. But then I found that you must get the gear up in a hurry because it too takes a large slice out of the take-off performance. That's where I had my first trouble.
As I've said, the gear is operated manually and is fitted with a counter weight to make it easier for the pilot to pull up all that-weight with one lever. That lever is pretty much like a straight flap handle. The hand-grip moves up and down on the main handle and is spring loaded. In the down position, the handle is forward and the spring-loaded handle has its tip snapped into a hole under the instrument panel; that locks it into the forward position.
As soon after take-off as possible you must reach under the panel, grab that handle, push down to release the tip from the hole, then haul back. When you get the handle all the way back, and the tip hooked into another hole alongside your right leg, the gear is up and locked. But I had quite a bit of trouble with this mechanism. Either the slipstream is responsible or the counter weight wasn't installed properly. In any case, I had such a tussle getting the gear retracted immediately after take-off I was afraid I'd accidentally let the ship dive into the ground. Yet you don't dare leave the gear down until you gain altitude, as you would with another plane. That extended gear takes too much away from the Mooney's performance, so you simply must get it up immediately, no matter how difficult. I can well imagine how my take-offs looked from the ground, as I ducked my head down to reach the gear lever, then cussed and sweated the thing into the up-and-locked position.
For safety's sake I think that particular feature should be changed. The gear-operating mechanism must be easier to operate and it must not force the pilot to pull his head down into the cockpit - particularly just a few seconds after the ship has left the ground and is still critically low both in altitude and speed.
Once in the air, with the gear retracted and the plane trimmed for level flight, the Mooney is delightful to fly. It's very sensitive to its controls; you can really "think" this airplane around the sky.
Maneuverability and stability are outstanding for so small an airplane. Despite the strong, gusty wind which had lightplane training craft grounded and tied down, the Mooney performed beautifully and revealed no unpleasant tricks. Except, of course, for that icing engine mentioned earlier. I was flying back to the Mooney airport at about 1,000 feet when the engine suddenly started to run down. Even though I slammed the throttle wide open and pulled full heat on, it kept on going down. I had already picked a smooth field to land in and was turning toward it when the engine slowly began to regain its power. Luckily the Mooney people had warned me to look out for icing; if they hadn't, I surely would have had a forced landing.
This characteristic is something Mooney is going to have to work out of his plane. Inexperienced private pilots have enough trouble with carburetor ice as it is, and this airplane, after all, is intended for the rank amateur.
With its low wing loading (7.4 lbs. per sq. ft.) and its low gross weight (700 pounds), the Mooney bobs around a bit in rough air. I had no trouble in normal flight but I had no luck whatever in getting maximum rate of climb. One climb I timed came out to 180 f.p.m., another came to just over 200. The best rate of climb the CAA could get during its tests at that altitude was barely over 400 f.p.m. At 2,000 feet the official rate is just over 300 f.p.m.
The Mooney has an excellent stall. There is a slight shudder at between 40 and 45 m.p.h. indicated but that's all. It doesn't even drop its nose sharply, just a gentle mush, with plenty of control. I made several tight turns at low speeds and the same slight burble gave me plenty of warning.
Cruising true air speed at 3,600 r.p.m. (1,800 propeller r.p.m.) is 80 m.p.h. Maximum-range cruise is at 75. Never-exceed speed is 120 indicated. Bill Taylor, Mooney test pilot, flew an M-18 from Little Rock, Ark., to Tampa, Fla. (900 miles) in nine hours, with a 10 m.p.h. average tail wind. On another trip he flew one 1,680 miles and got an average speed of 85 m.p.h. What's more phenomenal than anything else, of course, is the fuel consumption at those speeds: on the 1,680-mile trip Taylor averaged 1.55 gals. per hour. Other Mooney figures show the plane gets about 60 miles to the gallon and can be flown for between 45 and 59 cents per 100 miles, the cost of gas and oil.
First thing you do in preparing to land is to pull the carburetor heat on; the sooner the better. Then crank the trim handle back. For about three-quarters of the way back, the handle just operates the tail group (the whole tail moves up and down). That slows the ship down. Then you release the catch on the landing gear, let it drop down, then make very sure that the spring catch is care- fully locked in the forward position. Then crank the trim back the rest of the way, which automatically gives the maximum tail-down position and at the same time drops the maximum flap (16.5°). This is basically the same system as that used on the Culver V; both flaps and trim are interconnected.
Mooney has added another novel gadget to the M-18. Once it's trimmed for landing a conventional airplane -will suddenly go into a steep climb if the throttle is opened to any great degree. Mooney, however, has added a spring interconnection with the trim system on the M-18 so that, no matter how the airplane is trimmed, the throttle can be opened and closed suddenly without any drastic change in the plane's flight attitude. Despite the small amount of flap, the M-18 has a fairly steep descent. You simply point it at the spot on which you want to land, then sit back and wait. Normal glide is 57 m.p.h.
The Mooney's landing characteristics - especially with that 20 m.p.h. wind - are breath-taking. I had just gotten a green light from the control tower and headed for the end of the long runway. As I crossed a low fence just behind the run-up circle at the end of the runway I eased back on the stick. Suddenly, almost before I could realize what had happened, I was standing still. I'll bet I didn't roll two plane-lengths before stopping. I did the same thing several times later, and it was quite common to be landed and stopped within the diameter of the run-up circle at the end of the runway. This little plane's landings are as good as its take-offs are poor.
Although Mooney does have his CAA certificate (No. 803). he has not put this FLYING little plane on the market. To date he has produced about six, and each has gone to an operator who has agreed to participate in a market-research program. There is one M-18 in California, another in Florida, one in Kansas, and one in Ohio. Another is scheduled to go to New York shortly. Each of these air- planes is being flown by a wide variety of pilots and their comments are being sent back to the factory. Mooney is using this program to determine if there is enough interest in a one-place airplane to justify going into production as well as to work out the bugs.
It remains to be seen whether there is a market for such a plane. With the present limited production, the plane would have to sell for $2,050. Mooney wouldn't want to market it at all unless he could get the price down to $1,650, at least.
Unfortunately, the present used-plane market is pretty well loaded with good buys in that price range. And it's still debatable whether a one-place airplane would sell even under ideal conditions.
Meanwhile, Mooney is hard at work taking some of the bugs out of this intriguing little ship. High on his priority list is the take-off performance. Once that problem is licked he should find hundreds of enthusiastic followers. Personally, I would like very much to have one of these flying motorcycles for fast, economical travel in the vicinity of Washington.
23 July 2001