Hiper Bipe

My friend called me to his office one day and wanted me to build him an airplane that would be fully aerobatic and cross country full IFR with auto pilot. So we disgusted a lot of possibilitys. He had taken aerobatic courses in Cap 10 ,Decathlons and Steramans. He was an avid skydiver.
I said you look like a Hiper Bipe guy. And he said I salivate when I see one of those but I have been told they are to hard to build. I just shrugged. So It began.
It didn't take him long to find a kit that had been started.
We found an IO-360 200 hp Lycoming out of a Piper Aero. Bought a new Hartzel aerobatic prop.
It took a year and a half to make it fly. It wasn't the only project I was working on.
It was the day before Thanksgiving 1988. The FAA inspector met us at the hanger he looked the airplane over looked at the paper work and was taken back when he saw the gross weight I had set 2100lbs. He said your crazy. I told him the last TriPacers were rated at 2100lbs and this has just as much wing and a lot more power. He shrugged and handed over the airworthiness and said good luck.
Then my friend speaks up and I can go along on the first flight right?
The FAA man says if you need two pilots to fly it then yes.
I just about fell over I couldn't believe it. And he started in if I thought it was that dangerous I wouldn't even do it my self. Oh well.
First flight all checked out good lined up on the run way and he started talking on the intercom I tuned him out. I had had it up to 90MPH on the run way the day before.
Full throttle and we were off. At 80MPH I tried to lift it would not lift 90 MPH still wont lift 95 MPH it comes off but pretty mushy 100 105 and all of a sudden it turns into an airplane. In two seconds it is up to 130 and 20 deg. nose up and I am pushing froward on the stick. It's holding 130 MPH and 2500F/M and things on the ground are getting small real fast. At 5000 feet were only about 3 miles from the airport. I level off bring the engine back to 24 square 145 MPH and with full down trim I only have to hold finger pressure to keep the nose level. And my friend is talking a mile a minute. Looking at engine interments and everything is fine. Start feeling the controls and it has sever adverse yaw.It takes nearly full rudder for small aileron inputs to keep the ball near the middle.
I start with shallow turns and make them steeper it is all normal. Try a straight ahead stall. It starts to shake at about 100 and pays out at 90. Well lets see what the flaps do.Pull a little flap and it starts a little shake but otherwise no problems. Do some turns and the adverse yaw is less. Approaching the stall it pays out near 85.So I try full flap with 24squair it holds altitude at 100. The adverse yaw is still there but manageable even with full aileron and the aileron is really effective. I try to stall with power and it breaks between 60 and 70 with good warning. My friend is still talking.
It's been about half an hour it would be a good idea to get it on the ground and make sure we still have all the parts. I make a wide pattern with a shallow approach at 105 full flaps prop froward and 19".We are lined up with the runway about 500 feet to the right of the runway there are two poplar trees maybe 60' tall and 500 feet from the airport. We pass those trees and my friend stops talking. I glance over at him and his eyes are wide open. At about 5' above the ground and 300' from the pavement I chopped the throttle. We float to about 1/3rd of the runway and its a grease job 3 point on the center line. I turn off the taxi way and he starts talking. It seem when we went by the trees it dawned on him just how fast we were going. His Taylorcraft wouldn't even go that fast. We looked it over no leaks and every thing still seams tight.
I told him I would be back Monday so we put it away and I headed for Kansas. It was dark and I couldn't land the Colt at home so I went to Chanute. I called my wife to pick me up she informed me that my friend had called and he had flown it solo he was elated. When I called him back he was talking just like in the airplane what I remember him saying "its great" and "its a pussy cat".
I went back Monday I had been thinking about all week end. The front of the horizontal stab is attached to the sides of the fuselage with 3/8" bolts through a channel inside the fabric. So I drilled new holes 1" above the the original holes that reduced the negative angle of the stab.
So I flew it solo started the take off with full flaps and it lifted at about 65 I accelerated to 105 in ground effect then started to climb and retracted the flaps. I was at least 500 feet at the far end of the 3500 ft runway. At 5000 I leveled off and back to 24 square. It needed just a small amount of down trim to fly level with 145 IAS. The adverse yaw was still intolerable but some improved.I did a few take offs and landings and got conferable with full flaps and 85 on final.
The one thing that we didn't like was the kit manufacture literature called for a 160 cruse with a 180 HP and fixed prop.
MY friend would fly it every day. One day he called and said he found some thing strange.The rudder was not even with the top of the fin. So What had happened there were straps around the rudder spar with bushing rosette welds.With the sweep of the rudder when you push on the pedals you are trying to pull the rudder down inside the fuselage. The rosette welds had failed and let the hinges rotate down. So I built a new rudder. This time I used self aligning ball bearings. And the top hinge I made to have two bolts in the fin and that relived the tendency for the hing to rotate down. Now the rudder had a lot less mechanical drag and was easier to use.
Now we need to test systems I know he had been trying the LORAN but with a 50 mile radios test aria it was not to much of a priority.
Well he is in the left seat I in the right. 145MPH and he engages the auto pilot and let go of the stick. The stick instantly slams side to side the airplane turns sideways and I think flips end over end. It was difficult to grab the stick. I got the stick and found the auto pilot off then pulled the throttle. It stoped wings level inverted and nose down and low air speed. We were told that a rate based auto pilot had not worked for another builder.So I had also installed a yaw damper but it worked just to slow to be effective. So I took the fin and rudder home with me and built a new set 14" taller. Now it is the dead of winter 15 deg. out side there is a heated shop. So I use that shop to install that fin and rudder. I get the airplane as ready to go as possible open the shop door push it out jump in start up and taxi out and go. This is going good it doesn't need as much right rudder. At about 50' I retract the flaps and as usual were off to the races. At about 500' the left wing starts to go down and I try to put in right aileron its stuck.I try harder The stick goes all the way to the right and stays there. This thing dose a complete roll every 2 seconds and all I can do is push when it is inverted.I am thinking something under the seat is stuck. Maybe the flaps have something to do with my trouble I pull the flap handle hard and the stick is free. When I look out at the wing tips I figure out what happened.When the flaps are down the counter balances are above the wing in the cold air the aluminum ailerons had shrunk but the wood wings were still the same length. So back to the shop and adjust the ailerons for more clearance to the end of the wing.
The new fin and rudder vastly improved the adverse yaw now the controls work like an old airplane and the auto pilot works just the way we had intended in the first place.
As far as I know he still has it and flies it regularity.