Fin Offset
Posted: Fri Feb 17, 2012 5:39 pm
Richard, pulled your reply off the archives. I didn't receive as mail. Have you been officially subscribed to the list? Are you sending your mail to the list server instead of murphy-rebel@dcsol.com (murphy-rebel@dcsol.com) like you should be?
Anyhow, I forgot that the factory changed the tail spring retainer bolts to 1/4". This is so they can be used as rudder stops by putting a sleeve over them at the top. They do not actually hold any tail spring pressure, as the tail spring forces up on the fin post when on the ground. 3/16 bolts are definitely strong enough if installed properly as they only keep the tail spring from falling off in flight. Any shear load on these bolts from the stabs is minimal because both stab struts are usually pulling equally(actually pushing equally in positive flight) except maybe in a side slip, thus no shear load on these bolts. Keep in mind that the bolts holding the stab struts on are only 3/16 and these have compressive shear loads in positive flight and of course tension/shear loads during negative flight and no one has had one let go, KNOCK ON WOOD!
AS for the offset of the fin. 3/4 of an inch!!!!!! Do they want it to fly right hand circles all day without you!!!!!!! I offset my fin the original 1/2" (O-320 and Warp Drive) and I always need rudder in cruise to keep the ball centered and to keep flying straight. Don't need any rudder input on take off though. Both Howard Hanfords Rebel and the Rebel I just rebuilt (both O-320's and Aluminum Props) have no fin offset what so ever. They both need a little right rudder to keep the ball centered on takeoff, but both these aircraft will fly straight, hands and feet off for a hundred miles. I really prefer the rudder on takeoff and then its over with. If it were not for the necessity to make new fairings to cover the gap from the fin to stabs and the redoing of my dart style paint scheme on them, I would probably change mine to zero offset!!!!!
REBEL FLYERS, Richard has asked what everyone else thinks about fin offset, that are already flying. Lets hear the need for rudder pedal and how you mounted your fin. (straight or offset and how much!)
Blue skies and tailwinds,
Wayne G. O'Shea
www.irishfield.on.ca
Anyhow, I forgot that the factory changed the tail spring retainer bolts to 1/4". This is so they can be used as rudder stops by putting a sleeve over them at the top. They do not actually hold any tail spring pressure, as the tail spring forces up on the fin post when on the ground. 3/16 bolts are definitely strong enough if installed properly as they only keep the tail spring from falling off in flight. Any shear load on these bolts from the stabs is minimal because both stab struts are usually pulling equally(actually pushing equally in positive flight) except maybe in a side slip, thus no shear load on these bolts. Keep in mind that the bolts holding the stab struts on are only 3/16 and these have compressive shear loads in positive flight and of course tension/shear loads during negative flight and no one has had one let go, KNOCK ON WOOD!
AS for the offset of the fin. 3/4 of an inch!!!!!! Do they want it to fly right hand circles all day without you!!!!!!! I offset my fin the original 1/2" (O-320 and Warp Drive) and I always need rudder in cruise to keep the ball centered and to keep flying straight. Don't need any rudder input on take off though. Both Howard Hanfords Rebel and the Rebel I just rebuilt (both O-320's and Aluminum Props) have no fin offset what so ever. They both need a little right rudder to keep the ball centered on takeoff, but both these aircraft will fly straight, hands and feet off for a hundred miles. I really prefer the rudder on takeoff and then its over with. If it were not for the necessity to make new fairings to cover the gap from the fin to stabs and the redoing of my dart style paint scheme on them, I would probably change mine to zero offset!!!!!
REBEL FLYERS, Richard has asked what everyone else thinks about fin offset, that are already flying. Lets hear the need for rudder pedal and how you mounted your fin. (straight or offset and how much!)
Blue skies and tailwinds,
Wayne G. O'Shea
www.irishfield.on.ca