By T.M. Hoyt

Editor's Note

There are check pilot stories and check pilot stories. This one is different - an intercepted letter from one friend of ours to another - from Tim Hoyt, veteran Alaska Airlines and ATC Hump pilot, now flying for Mathieson Chemical Corporation, to McKean Carmichael, vice-president of R.L. Polk & Co., a veteran light plane pilot who has just had his single-engine Navion converted to a Twin. When Mr. Carmichael has had a chance to evaluate his new ship, FLYING will present his views in a similar article.

Dear Mac:

As you know, some time ago Mathieson Chemical Corporation bought a Twin Navion. They wanted a twin-engine plane in a low price range, economical to operate, with a high safety margin on single-engine, and one that could get in and out of small airports. Neil Fulton, Mathieson's Chief Pilot, chose the Twin Navion, powered by 150-Lycoming engines, swinging Hartzell props.

Mr. T.C. Keeling, Jr., President of our Hydrocarbon Chemicals Division, who had considerable time in your single-engine Navion, felt that a Riley Twin could be utilized in his work. That, as you know, is where I came into the picture. I was hired as Captain on the company DC-3 in order to keep up my heavy equipment experience, and to take over the Twin Navion.

I had never flown a single Navion and, in fact, have very little single-engine experience. I liked the Twin right off. It has very good flying characteristics. With 150 Lycomings and Hartzell props, it measures up to all we wanted.

As the ship originally had 140's, Riley installed the larger engine and Hartzell props, which make all the difference in the world in the plane's performance. Mac, you are going to love that airplane.

When they finished our plane at Ft. Lauderdale, I ran some tests on it. It really has single-engine performance now. With a gross load of 3,450 lbs., I maintained 8,000 ft. on one engine and didn't drop below 90 mph indicated air speed. At 4,000 ft. with the same load, I was indicating 120 mph on single engine. At both altitudes I didn't use power above 2,600 rpm and 25 inches of manifold pressure.

I cut an engine at low speed of 80 mph and higher speed of 160 mph. The only effect you get in either case is a horizontal yaw that is easily controlled. The plane has no tendency at any speed to roll or go out of control. The rudder trim is ample to give you straight flight on single-engine. You do not have to hold rudder during single-engine operation.

From this point I proceeded to cut engines in every position I could think of. I cut the inside engine in a 45 bank with no bad characteristics showing up. I made a 45 bank into the dead engine and lost no altitude and the ship had no tendency to stall or drop off.

After all this I was convinced that the ship would climb out from take-off on one engine. With full tanks and some baggage, I tried it myself. I figured my gross load at about 2,875 lbs. At 75 mph she flew off. I pulled the gear up and held it down for single-engine speed of just over 100 mph and feathered the right engine. The ship had no tendency to drop. My rate of climb was never under 300 feet per minute and air speed between 95 and 100 mph. Directional control was easily held with rudder. I climbed to 500 feet with 2,600 rpm and 26 inches of manifold pressure. That means that if I wanted to I could still boost it to 2,700 rpm and 28 inches. I continued a normal pattern and landed on single-engine.

Nine times out of ten an engine will not quit cold, unless by cockpit confusion or a broken gas line. You will have some power left. This will usually afford you time to make your decision. Of course, there is that one chance out of ten, so I cut an engine on the take-off roll. I didn't cut the other one back immediately, as I wanted to see if it could be handled if it came by surprise. With the steerable nose wheel, I found that it can be easily controlled and the other cut back with no trouble resulting.

Climb Performance

With a full gross load you will get an indicated air speed of 160 at 8,000 feet. This I did at economy cruise. Up to 10,000 feet with climb power, I had at least 600 feet per minute climb. From take-off I can climb at 120 mph and still get about 1,000 feet per minute up to about 7,000 feet.

I was told at various times that the best climb speed with the single-engine Navion is 100 mph. That may be true, but it is now a twin-engine ship, so your first thought after take-off should be to establish single-engine climb speed of before continuing your climb. This ship climbs very well at 120 mph, and the engine instruments are normal for climb at that speed. By holding level flight after take-off, in a matter of seconds you establish 120 mph and have ample speed in the event single-engine performance is required.

At first my gas consumption was about 20 gallons per hour. Now after experimenting with mixture settings I find that we run between 17 and 18 gallons an hour. Without accurate gauges, I calculate my consumption at 20 gallons per hour. This gives me a total of three hours fuel. We hope to add another 20 gallon fuselage tank soon. This will give use four hours or a range between 500 and 600 miles.

I can't say that the ship isn't an instrument ship because it does handle very nicely on instruments. Consider the elements of weather, then decide for yourself.

On the weather map sequences and forecasts you may find diagrammed the exact situation that you ran into the week before, but when you get into it, find it completely different than you anticipated. At one altitude a ship can run into severe icing conditions, while at another there may be little or no ice. Many an airline has taken off assured that the weather at his destination will hold, only to have it fall flat on its face just before he gets there. His situation then is not critical. He can get down to a minimum ILS approach altitude with a load of ice, pull up, and with his de-icing equipment and power plants go back up to an altitude he chooses. Without proper de-icing equipment, ice on your props may not allow you the efficiency to do that. I found that I can easily establish a rate of descent of 500 feet per minute at a given air speed of 100 mph, but don't think I could carry enough power to keep my engines warm enough to take a sudden burst of power, if I came out of an overcast and suddenly found I needed it. This ship is still a light aircraft. In rough air on instruments, it would probably bounce around.

Radio Flying

Another instrument problem is radio. An airline takes at least five separate radio sets into a congested area, such as New York. They have two pilots, one to fly the ship and one to take down the current weather conditions and clearances. Those two men are busy from the time they start an instrument flight to the time they come to a stop at the ramp. In this ship on man is trying to do it all alone with limited radio equipment. Also, gas range is limited for instrument flying. You don't really have enough gas to go into a known weather area and get to an alternate airport that is out of that area if your destination should close down.

If a pilot does it day in and day out, sooner or later the percentages are going to bring up a situation beyond his control. If he doesn't do it day in and day out, his proficiency is going to get rusty and he adds that much more chance against his doing it successfully. A pilot is only as good as his judgment.

Basically, we have a ship with full panel instruments. We fully intend utilizing it under certain weather conditions; for example, on top flying, if the destination is clear or affords 1,500 to 2,000 ft. ceilings and the weather elements are not too severe. In this way our ship is going to afford the corporation in the neighborhood of 75% yearly utilization. The other 25% isn't worth the risk.

If utilized properly the Twin Navion has numerous advantages. For example, I can go to Norwich N.Y., which has a small grass airport not served by the airlines. To get there from New York and back by other means would take two days. With the Twin we left LaGuardia at 9 A.M. and were back at 2 P.M. that afternoon.

We don't try to make long trips in a short time. If a long trip comes up, we can usually work in several calls along the way. For example, a trip to Chicago and back was made in Louisville, Chattanooga, and Akron without excessive stops for gas alone.

All in all, Mac, I'm sure that when you get grooved in on your Twin you are going to get a lot of fun and use out of it.

As always,

Tim