Q-talk 132 - Tri-Q Front Fork Setup Procedure
- Category: Q-Talk Articles
- Published: Wednesday, 23 December 2009 16:24
- Written by Doug Humble
- Hits: 1518
A question about how to set up the front fork on a Tri-Q came up on the Q-List recently. It was concluded that this procedure had not been documented before. I will try to do so here with the help of Kevin Boddicker who has made these changes.
Kevin wanted to raise his ground angle of attack on his Tri-Q so that it would take less back pressure on the stick before his Tri-Q would rotate on takeoff. Kevin says the Tri-Q's have the same angle of incidence as their tail dragger cousins, if built per plans. Therefore, on the ground, the Tri Q's have a negative angle of attack compared to the tail dragger versions. The Tri-Q's won't just levitate off the ground on take off like the tail draggers. Kevin says you have to yank them into the air. This abrupt takeoff maneuver can cause pilot induced oscillation (PIO) because immediately after leaving the ground your angle of attack is too steep, and the pilot must nose the aircraft back down. This could cause the pilot to overcorrect causing the PIO. Everyone would agree that PIO close to the ground could be hazardous to ones health.
Before implementing this set up, Kevin got approval from Scott Swing, the manufacturer of the Tri-Q landing gear. You can see in the "original setup" photo, that only the phenolic washer was above the fork. In the new setup both cupped washers and the phenolic, along with a flat washer are above the fork as follows: top cupped washer against the welded washer on the fork with the cup UP. The second cupped washer pointing down, then a flat washer next to the phenolic washer. The fork comes next. The thin flat washer goes between the fork and the nut.
Kevin says that over the nose visibility has suffered slightly, but the takeoff procedure is more normal and the PIO has been reduced significantly. "Your mileage may vary"
You can order a printed copy of Q-talk #132 by using the Q-talk Back Issue Order Page.