The Davis DA-5
By Leeon & Harold Davis
The design theme was “keep it light, keep it conventional in layout and construction, but above all, do not compromise on aircraft standards”. The challenge was to prove that an uneducated father (12 years of school) and his eighteen-year-old son could develop, virtually overnight, a new design if the above theme was maintained. No non aircraft engines were ever considered. In fact, the design concept was sparked by the poor performance and reliability of these engines.
The first engine to be tested was the Franklin 2A-120-C but provisions for mounting a Continental were also made. When the Franklin delivery schedule was not met that mount was laid aside (4 working days lost) and a new mount was built for an old reliable Continental A-65. The performance with this engine has been above our expectations. Minor clean-up has boosted cruise to over 140 mph; the eventual goal is 150 mph. Wheel pants, improved cowl, and the optimum prop should produce this.
The design dates back to October and November of 1972. Many nights of figuring and sketching were done but time permitted little actual construction. The ailerons (less balance), 1 tail tab skin, instrument panel, 2 aft fuselage skins, and 2 aft bulkheads were built and collected dust. On May 3, 1974, while looking at the parts collecting dust in out storage shed, my son, Harold stated that he was going to finish that plane. The parts were gathered and dusted off. The paper work was located and a new Franklin engine ordered. Getting to Oshkosh was Harold’s goal so I could see I’d better clean up some of my work and pitch in. First I had to paint the original DA-2A which I had just sold, and then I helped my wife refinish an antique table. It was mid-May by the time I got into the project with both feet. It would still be another two weeks before Harold would be out of school. Friends looked an amazement at the pile of parts we planned to fly to Oshkosh. There were few setbacks and we were only about seven days behind schedule when we flew on July 22. The aircraft was hauled to the airport at midnight and early the next morning two high speed runs and four lift offs were made. Travis Boren, our friendly aviation advisor, arrived at 10:30 and by 11:00 we were ready to go. The first flight was picture perfect and no changes were made before Steve Fenton, a Davis owner, crawled in behind me to become the second pilot. By sunset we had flown six hours and found one problem. One of the nose wheel donuts which was made from a rubber hammer had broken. This was quickly replaced with an oil well packing washer. The flight test program was more of a test of pilots than the aircraft. Sunset was always a welcome sight and emphasis would shift to finish up work. Two more small problems cropped up and were quickly fixed. We had to install double trim springs to handle the aft C.G. This problem we had anticipated. The long exhausts which exit in the air outlets on each side cracked at about 20 hours and were shortened and reinforced. The bend at the end which kept the exhaust off the fuselage was probably causing them to vibrate. Later these gave way to four straights which allowed the lower cowling to be made smaller. Sound level in the cockpit was reduced while the exterior sound remained about the same.
Flight test went so well that we got back on schedule and left for Indiana the 27th and on to Oshkosh the 31st.
The aircraft is a real joy to fly because it has lots of zip and control response. The long nose makes you feel you are in a mini fighter.
When Harold, a student pilot, flew the DA-5 for the first time he was quite pleased. As he flew by on his first climb out he waved so I knew he was home in this strange aircraft. He was relaxed as soon as he left the ground and felt the controls.
Unlike the DA-2A the forward visibility on landing is hampered by the nose. In level flight visibility is very good.
I believe that the semi-supine seating is the only way to go for a single and 2 place side-by-side. I’ll admit it would wreck the C.G. on larger aircraft. It certainly improves cruise, appearance, and comfort. The seat bottom is part of the structure. Only the seat back moves. There are four seat positions and the upper holes are farther apart then the lower. This helps to get the over 6 footers into the small fuselage (34 ½ deep).
Structural features are either like the DA-2A or very conventional. The main gear was the most radical departure and it has proven unsatisfactory for dirt strips. It is simply a piece of streamlined wing strut material mounted rigid to the spar with only the tire for shock. The same simple light weight leg and axle will be retained but with a rubber socket in the wing for additional shock. The wheels and brakes are by Rosenhan. (NOTE: The current main gear configuration is the same style as the DA-2. The plans do not show this gear design)
The all flying “V” tail which has been quite successful on the DA-2A was retained and scaled down. The mounting is similar but the intersection at the fuselage has been improved. The tail and ailerons are 100% mass balanced. The tail is balanced at the tip on a protruding tube. The ailerons are balanced new the tip inside the wing.
The fuselage consists of only four skins. The forward lower is .032 and the forward upper and two aft skins are .025. Formers consist of a stainless firewall and four bulkheads. The bulkhead behind the seat is 5/8 sq. tube and provides roll over protection. Five-eighths square tubing also runs forward from this bulkhead to the firewall and provides for upper engine attachment. A tube cross member is located at the firewall and instrument panel bulkhead. This welded assembly provides for a light weight safety structure. External extruded angles at the lower corners of the fuselage provide for lower engine attachment and pickup wing spar torque loads. The tail skid also carries lower fuselage loads and provides for tie down.
The canopy hinges on the left and swings over to hit a bumper on the fuselage. A double lock on the right keeps it snugly closed in flight. The one-piece windshield is of commercial storm door plastic. It can be bent without heat.
The one-piece wing is of single spar construction with stressed skin. The main spar upper and lower caps are extruded aluminum angles. They are 10 ft. long. Twelve ft. is standard length. The dihedral angle is bent in. The web is corrugated is six places for vertical stiffening. The outer web is formed to a channel to form the spar beyond the cap angles. The two webs are spliced at the center line. There is a total of 67 pieces in the wing structure. This includes items such as a pitot tube, tie downs, aileron hinges and stops, inspection plates and doublers. The rear spar is a simple channel and carries only torque and aileron loads. The ribs are made on form blocks with planned wrinkles to take up excess metal. 2024 T3 is used for all ribs and they have three sizes of flared lightening holes. There is a wing walk on the right side only. The wing has only four skins. The inboard skins are 48 inches wide (standard sheet width) .025 and are wrapped from T.E. to T.E. The outer skins are 36 inches wide (standard sheet width) .020 and are wrapped from rear spar to rear spar. The wing assembly weighs 58 ¾ lb.
The engine nose wheel mount is of conventional tube construction. Nose wheel shock is absorbed by seven rubber donuts. Steering is direct to the rudder pedals. The nose wheel is GERDES and the tie and tube are commercial.
The new cleaner cowling which is shown in the three view will be better looking and should reduce vibration and noise level.
This aircraft was not intended for aerobatics nor would I want anyone to build with that intent.
With this little aircraft you do not need to build a trailer to go to those far out fly-ins. With over 140 cruise and dependable aircraft power those far out fly-ins are just hours away. And you can take a suit case, sleeping bag, and a small tent in the baggage are. In other words it’s not just for around the patch.