Ardent
Active Member
- Joined
- Mar 27, 2007
- Messages
- 31
I'm looking to find a hydraulic cylinder with a ~1" bore and 4"-6" stroke (easy), but it's gotta be light (tougher). All the industrial/standard hydraulics are heavy little buggers. I've looked into pneumatics but with a 1" bore their ~250psi type operating pressure will only give me roughly 200lbs of force at peak psi. This isn't enough as the pressure will be the locking force for the gear, and pneumatics bleed pressure faster. Also, a simple hand pump will do nicely for hydraulics, but pneumatics get more interesting. I'll likely pass.
What I'm doing is putting retracts in a Hummel Ultracruiser build (I'm from Canada, we're not bound by the same weight limits on our ultralights as ultralight pilots here must be licensed and tested so the category's somewhat different). So the gear is extremely light, on the order of less than 10lbs per leg. I will be using an axle in the wing the gear leg's fitted to, with on offset arm manipulated inside the wing by the cylinder to rotate the gear up/down.
While I don't have to sweat the weight limit, I do still have to be concerned with weight. I'm looking to find an aluminum cylinder, or an alternative if somebody here has a bright idea. Using conventional cylinders will easily add 30lbs+ vs. fixed gear. A lot on a 270lb plane, I don't really need to add. Any leads? I'll also need a lightweight manual pump, something aluminum. I was thinking something from sail racing perhaps as I've seen backstay tensioner hydraulic pumps with aluminum bodies kind of along the right lines, but not quite. I have a 20 amp electrical system but wish to avoid any electrics in this system.
What I'm doing is putting retracts in a Hummel Ultracruiser build (I'm from Canada, we're not bound by the same weight limits on our ultralights as ultralight pilots here must be licensed and tested so the category's somewhat different). So the gear is extremely light, on the order of less than 10lbs per leg. I will be using an axle in the wing the gear leg's fitted to, with on offset arm manipulated inside the wing by the cylinder to rotate the gear up/down.
While I don't have to sweat the weight limit, I do still have to be concerned with weight. I'm looking to find an aluminum cylinder, or an alternative if somebody here has a bright idea. Using conventional cylinders will easily add 30lbs+ vs. fixed gear. A lot on a 270lb plane, I don't really need to add. Any leads? I'll also need a lightweight manual pump, something aluminum. I was thinking something from sail racing perhaps as I've seen backstay tensioner hydraulic pumps with aluminum bodies kind of along the right lines, but not quite. I have a 20 amp electrical system but wish to avoid any electrics in this system.
