- Joined
- Oct 30, 2003
- Messages
- 18,363
- Location
- Santa Maria, California
- Aircraft
- Givens Predator
- Total Flight Time
- 2600+ in rotorcraft
Hello Thom,
The funding roadblock has been removed.
When I left Scappoose I was going to use a real aircraft engine, but Paul talked me out of it on our way past Sturgis, South Dakota as we headed to Air Venture. Three weeks with a pod caster and sleep deprivation can be a real challenge to ones judgment.
When Paul came by the house he loved all the junk we have already built and rejected. We feel that part of a successful project is how much stuff you throw away because you figured out a better way to do it. Based on that it should be a successful project.
We recently abandoned the supercharger and direct drive. We felt that we could not dampen the torque pulses of the high power output at low rpm and the new main bearings they are using are a little weak for the kind of loads you get from a propeller.
We just scraped the cam cover drive for the pre-rotor pump because with the re-drive the engine rpm goes up and the pump speed would have been too fast. We may drive the pump off the cam instead of the crank or us an external drive.
Other than the vibration the HD engine is not that bad, 95 cubic inches and 87 horsepower at 4,800 rpm. It is still making 54 horsepower at 3,000 rpm. It weighs less than 140 pounds bare and 165 pounds with the re-drive, starter, charging system and exhaust. I have several laying around, one that makes around 118 horsepower at 6,600 rpm. The HD engine also has a pleasing exhaust note.
We learn things faster than we can build; so the ongoing redesign slows progress.
We are trying to keep it simple and conventional.
We are trying to make the frame stiff enough to raise the natural resonance of the extremities above the frequency of the perturbations. I am pleased with the new truss and engine mounts. The new tail, Doug’s fault, will put a lot of torsional loads into the tail boom if we allow it to resonate. The three-sided truss is fairly good in both torsion and bending. It has a solid connection to the engine mount/rotor tower.
The re-drive and pre-rotor drive are our focus at the moment.
It is a hobby project so it takes on a pace and timing of it’s own.
Thank you, Vance
The funding roadblock has been removed.
When I left Scappoose I was going to use a real aircraft engine, but Paul talked me out of it on our way past Sturgis, South Dakota as we headed to Air Venture. Three weeks with a pod caster and sleep deprivation can be a real challenge to ones judgment.
When Paul came by the house he loved all the junk we have already built and rejected. We feel that part of a successful project is how much stuff you throw away because you figured out a better way to do it. Based on that it should be a successful project.
We recently abandoned the supercharger and direct drive. We felt that we could not dampen the torque pulses of the high power output at low rpm and the new main bearings they are using are a little weak for the kind of loads you get from a propeller.
We just scraped the cam cover drive for the pre-rotor pump because with the re-drive the engine rpm goes up and the pump speed would have been too fast. We may drive the pump off the cam instead of the crank or us an external drive.
Other than the vibration the HD engine is not that bad, 95 cubic inches and 87 horsepower at 4,800 rpm. It is still making 54 horsepower at 3,000 rpm. It weighs less than 140 pounds bare and 165 pounds with the re-drive, starter, charging system and exhaust. I have several laying around, one that makes around 118 horsepower at 6,600 rpm. The HD engine also has a pleasing exhaust note.
We learn things faster than we can build; so the ongoing redesign slows progress.
We are trying to keep it simple and conventional.
We are trying to make the frame stiff enough to raise the natural resonance of the extremities above the frequency of the perturbations. I am pleased with the new truss and engine mounts. The new tail, Doug’s fault, will put a lot of torsional loads into the tail boom if we allow it to resonate. The three-sided truss is fairly good in both torsion and bending. It has a solid connection to the engine mount/rotor tower.
The re-drive and pre-rotor drive are our focus at the moment.
It is a hobby project so it takes on a pace and timing of it’s own.
Thank you, Vance