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How To Fly A 4-Place Cessna Glider

By Bob Park

A funny thing happened on my way from Harper County to Reno County about three years ago. The engine in my Cessna 175 lost a couple hundred RPM. I advanced the throttle, but the engine started to run quite rough. I knew that an explanation of why it quit would be more trouble than to explain why I shut it off, so I shut the engine down and slowed to nearly a stall before the prop quit windmilling, at which time a cloud of blue smoke drifted from the cowling and past the windshield. I was only about 8 miles from my home field, and about 7,500. ft AGL, so it was an easy glide back home with a normal traffic pattern and landing. I was able to land and turn off the runway onto the taxiway and coast part way to the hanger.

I had been planning to replace the engine, and wanted to install a Continental 0-470, 130 horsepower engine such as the Cessna 182 has, but that has not yet been approved. Since the airplane had decided I needed to put a different engine in it, I bought the right to use STC SA 122 NW, which is approval for the installation of the engine I wanted. This STC was approved in 1974. I now own the STC.

The airplane was at Harper, Kansas, and I wanted it at Halstead, Kansas, where there was a willing mechanic. This was about 60 miles away.

I went to the FAA in Wichita, the Flight Standards District Office, and asked for a Ferry Permit. When they asked what was wrong with the airplane, I told them the engine doesn't run and I planned to tow the 175 with a 182. That got their attention, and was the start of 15 months of discussion and effort.

At a meeting of myself and several FAA persons, many questions were asked, and only one FAA man said he thought we could do it. The main concern appeared to be that they believed the 182 would not be powerful enough.

A plan for the towing was presented to FAA and another meeting was held. Many items were covered, and it seemed that another FAA person was beginning to think it could work. The regulations provide for towing a glider, but require a waiver to tow anything else. The certification for the 175 describes it as an airplane, therefore that is what it is and it can never be a glider so a waiver will be required. The chief man at FSDO says there will be NO waiver.

FAA opinion is that I could dismantle the airplane and haul it so there is no need to tow it.

Fortunately, some FAA persons understand their purpose and believe one should be allowed to try what they want so long as the public is not at risk - which is what the FAR say. I built a tow hook with which to replace the propellor, and was granted approval for that. I now have an airworthy airplane with a tow release and no propellor.

One day with clear sky and about a 25 mph wind right down the runway the 175 was attached to a Honda Gold Wing motorcycle with a 200 ft rope and the 175 indicated 80 mph, control was good, and an altitude of about 10 feet was maintained for 20 seconds or so then a normal landing.

A call to the FSDO office was made and I told them what we had done with no problems, and this without any engine cowling. They were impressed.

More serious discussions with FAA indicated they still were concerned about the ability of the 182 to tow. I had towed two gliders at once with the 182, and the total weight of those was higher that the 175 would be. An FAA test pilot had made a computer print-out of his analysis and said the performance would not be good. He had used gross weight of both aircraft, and a speed in excess of what would be required. I was told there was no way to predict what the performance would be.

This old Farmer thought he knew better, and having the benefit of some practical experience, set out to see just what the performance might be.

I made some tests and recorded the performance of the 182 to determine what power was required to maintain altitude with various flap settings and airspeeds. I also recorded rate of sink at various airspeeds and flap settings with a no-thrust power. I also recorded rate of climb with various flap settings and airspeeds at full power. Take-off distances were also recorded. Barometric pressure, wind speed, and temperature was recorded, humidity was not recorded. I also knew the weight of the 182 as flown. The handbooks for the 175 and 182 list performance, the two airplanes takeoff distance are the same and the wind correction are the same.

From the weight of the 182 and the rate of sink at zero thrust, and the actual power to maintain altitude as shown by the engine power curve using the manifold pressure and rpm, I had an indication of the actual power required to fly the 182. Double that would also fly the 175.

The propellor appeared to be 60 percent efficient. This seems an acceptable number to use. Since I knew the rate of climb for the 182 and the weight of the 182, I could figure the horsepower used for that rate of climb.

Based on these numbers I told FAA the take-off distance would be less that 1000 feet and the rate of climb would exceed 250 feet per minute with the weather we could expect in May and the wind of about 1O mph which is what I wanted.

FAA finally agreed I could try a tow at a long runway. Sunflower Gliderport was acceptable. I bought another 175 for these tests.

I really appreciate all the help that was available. We made three test tows at Sunflower with witnesses, still pictures, and video recordings made from inside the 175 and from along the take-off and landing runway. Another day we made two tows, one of them using a 100 ft tow rope. All went very well. The take-off distance was 960 feet and the rate of climb was 260 fpm verified by variometer with route recording capability.

The video was presented to FAA properly, and there was no doubt that the proposed tow could be done safely. Another application for waiver was made for the trip to Halstead and was approved - signed by the Chief FAA man at the Wichita FSDO. Within 24 hours of receiving the authorization, the tow was done and the 175 was at Halstead. There were no problems. It took less than 1 hour from start to done. Much better - and safer - than disassembling, hauling, and reassembling.

I appreciate the right to apply for the authority to do this. As the effort progressed, more and more FAA personnel came to accept - and even assist in gaining the approval. I thank them for the help. I was told by a FAA man many years ago that you can do anything if you go about it right.


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Published and maintained by Jerry Boone, Hutchinson, KS