Customer Profile

Colorado STOL CH 701 Builder Installs Turbo Rotax 914 for Mountain Flying

Clarence Wood's Rotax 914 installation

Clarence Wood's Rotax 914 installationHere's an update on the engine change made in my STOL CH 701, with the Rotax 914 (101 hp) replacing the Rotax 582 (65 hp) and the associated performance.

My purpose in making the.change was to attain a superb rate of climb over a wide altitude range since I fly from a 5,000' elevation strip and often need to go to 12,000 -13,000'. In brief, after 20 hours of test flying I have ample proof of having attained the objective. In the course of testing I have gathered same data I feel would be interesting to you. I do not consider this information to be highly accurate since it has been gathered with only a stop watch, sensitive altimeter, manifold pressure gauge and the airspeed indicator.

Following is an average of the data collected to date:

Rate Of Climb OAT: 50 F approx.; IAS: 45 mph; Wt: 850 lbs. approx.; 5,000 - 8000 MSL.
  Max Power (115 hp through 8,000 MSL) 2,050 fpm
  Max Continuous Power (100 hp) 1,600 fpm
  75% of Max Cont Power (75 hp) 800 fpm
Cruise Speed A comfortable cruise of 72-74 mph is attained at 45% (45 hp) of Max. Cont. Power
Takeoff Run It is difficult to obtain accurate information since the brakes cannot hold the aircraft for engine run-up and the aircraft is airborne before full power is attained. My judgment is that takeoff distance has been reduced 20-25%.
Service Ceiling I have not completed this phase yet and will report on it later. I expect to make runs up to 20,000' MSL.
Other Information The engine is equipped with a 68"-3 blade Warp Drive propeller set at a 13 tip angle. The angle may not be optimized.yet.
  You will note from the photos the plane is equipped with all-terrain gear so all performance data collected incorporated this gear.
  Empty weight is 593 lbs. Addition of the 914 engine, larger battery and heavier propeller resulted in about a 70 lbs. increase. Other increases came with upholstery, heavier landing gear, ELT, instrumentation,etc.
  The engine and turbo control system have worked very well so far. As you can see from the photos a Rotax oil cooler is installed at the cowling inlet. Since cruise is at such a low power setting, fuel consumption is averaging only 3.5 gal/hr.

Clarence Wood's STOL CH 701 with Rotax 914 installation

This about summarizes things at this point. I will let you know how the altitude tests turn out (with oxygen tank).

Along with this letter I am enclosing a photograph of my CH-701 (Serial Number 7-1702 with a 582 LC engine) which is now completed and flying.

I purchased the kit July 1991, picking it up at the factory. Construction time turned out to be 425 hours excluding the painting. Painting was performed by a local auto body shop using a urethane system. FAA airworthiness approval was obtained August 27, 1992 and the first flight was September 5th. At this writing I have 28 hours of the 40 hour restriction flown off. All performance characteristics seem to be very close to those advertised and those of the two factory demos I flew when I picked up the kit.

This was my first experience working with sheet metal and rivets. I found it to be simpler than anticipated and very straight forward. On several occasions I spoke to Matthew and John with questions and always found their direction to be both correct and helpful.

My kit included the FWO, two wing tanks, hydraulic disc brakes and the cabin heat options. Empty weight without seat cushions was 474 lbs. Center of gravity was no problem.

I live in mountainous terrain and fly from a dirt strip (Elevation 4,720) so altitude performance is very important. So far I have only flown up to about 11,000 MSL but I believe the altitude performance will be very satisfactory.

I am very pleased with the airplane as well as the kit and look forward to many years of pleasant flying with a very good STOL design.

This article is presented as part of a series where we profile customers and their building and/or flying experiences or stories. The views, opinions, or technical data do not necessarily reflect those of Zenith Aircraft Company. The information is provided strictly for entertainment and education.

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Zenith Aircraft Company: 2000-05-15