DR-1 Tri-Plane, ¾ SIZE
Travis H. Gier
Empty Weight = 535.5
Build Time: 7 months @ 493 hours
Engine: 2180 cc VW from Great Plains Aircraft with 2 to 1 re-drive
Propeller: 8046 Culver City
The Following is a summary of my DR-1's handling characteristics
I'm sure you have heard horror stories about the WWI aircraft and their atrocious handling characteristics. I know that I've heard many. The DR-1 Tri-plane is so unique that I fully expected a lot of little idiosyncrasies. I have heard all the stories- from dangerous ground looping to the severe adverse yaw problems that were surely going to kill a man. While you read through my report you will be able to see what Airdrome's little Tri-plane has evolved into. Each section is labeled with that phase of flight.
I know, I know. It is going to ground loop. Nothing could be further from the truth. There is plenty of control and I have yet to have the first tendency of a ground loop show up. Control is both firm and positive. In addition, I have brakes on my plane and I wish I had not bothered to put them on. With the slow putter, putter of the VW, it will idle at a dead stop on pavement. You will have to perform "S" turns for visibility during taxing, but that's to be expected.
From a dead stopped position, to wheels off, takes approximately 155' on pavement (180' on grass). I've found that smooth continuous throttle advancement to full power, with down elevator until tail comes up, will result in little, if any rudder input required. After the tail comes up, I neutralize the elevator and she will lift off on her own at 38 mph. I climb out at full power (4200 rpm) at 55 mph which gives me 1250' FPM.
I cruise at 3450 rpm's which results in an airspeed of 71 mph. I have changed the incidence on my stab from what is shown in the drawings. My rear mounting spacer is ½" thick and the forward mounting spacer is 1 ½" thick. By increasing the stab incidence it causes the tail to be higher in level flight, which increased the visibility over the nose. She will fly hands off, but you will still need to keep a little pressure on the rudder to keep the ball centered. Without the benefit of a fin to keep you tracking straight, there is a natural tendency to yaw.
Turns should (I feel must) be coordinated. I have a large T.C. that I regularly glance at. I've discovered that I'll get a little blast of air on my face when I'm slightly uncoordinated in a turn, (I have a small windshield). Remember, "Step on the ball" and turns can be as steep and tight as you want. There doesn't appear to be any adverse yaw to the left, but there is a very small amount to the right. This may just be my airplane or it may have something to do with torque or P factor. It really isn't much. Turns should be coordinated anyway.
I've approached landings as follows: Pattern altitude until on final. After turn to final I carry 55 mph to the numbers. At the numbers I'll back off to 45 mph until wheels touch. I touch down on the mains only. Once the mains are on I reduce power smoothly, holding a little down elevator to gently let the tail down slowly. Once the tail is down I hold full up to keep it stuck during rollout. Just keep her straight with rudder input, it won't take much. She slows down rather quickly and total roll-out on pavement is about 400 feet, compared to 300' on grass. If you try to 3 point your landings, you're asking for damage. Because the sink rate at these slower (- 40 mph) speeds is considerable, what will happen is the plane will see-saw between the main wheels and tail wheel. Eventually you will break something. Keep your approach speed up to 55+/- mph, and your sink rate low. Touch down on mains at 45+/- mph. Fly to touch down!
Don't be afraid to allow some sloppiness in your main shock cords. They will definitely smooth out the rough spots. This is certainly not every ones choice of landing methods. My Extra 300 lands best in a perfect three-point set up and stays stuck to the ground.
Stalls with power on occur at 34 mph, totally predictable and straight forward. You won't really make a bull break, but you will notice that your sink rate really goes up. Recover by pushing the nose down and flying out of it. Stalls at no power are different! As before, predictable and straight forward but you will get a HUGE sink rate followed by a drop of the nose. Simply relax the elevator. Add power and fly away.
Both left and right happen quickly at steep angles of attack. By applying full rudder it will spin very tightly. NEVER-NEVER-NEVER look over the top wing to orient yourself for recovery from a spin. ALWAYS- ALWAYS- ALWAYS look straight ahead over the cowl to orient yourself!
Intentional spins should not be performed due to the extreme loss of altitude and unknown airframe stress. It will take approximately 11/2 – 2 turns to defeat the spin once recovery has been initiated.
My home field has a 36/18 runway, both grass and paved. Seven days out of ten the winds are 9/27. I have landed and taken off in as high as 12 mph crosswinds. I've also passed on a day's flight when the winds were at 15 mph. If you really do want to ground loop, land with heavy crosswinds – "Avoid Heavy Crosswinds."
GENERAL FLIGHT CHARACTERISTICS
I've found the plane to be rather predictable in all aspects. Rudder and elevator response is more that adequate, but light. Ailerons are heavier (but that is to be expected due to wing mass), yet they have plenty of authority. At lower speeds (40 mph) there is a high sink rate. There is no real glide. Airspeeds must be kept up (45+ mph) or you will begin to sink. It is my policy that if I had an engine out, I would look for a landing site anywhere within a 45* angle, aim for that spot and stick to it.
This plane is a lot of fun to fly. People really notice it. I have had people follow me from the interstate highway to my field jus to stop and take photos. Everywhere I go the plane is a hit.
The following are my only deviations from the plans:
- Padded fiberglass bucket seat rather than sheet material.
- Different tail wheel
- Increased stab incidence
- Entry peg (step)