Razor Back Option

[MotReklaw]

I like it too, but no experience with how it performs.

[jtpitkin06]

The razorback option applies to the model 7 SS. It is a 3 inch high dorsal fin extension to the vertical stab reaching forward and tapering to zero height at the rear of the baggage compartment.

According to the supplement in the builder's manual it "does add to the yaw stability of the aircraft."

The option is made from a 5 foot long piece of aluminum tube and a plywood rib. The parts weigh about 7 ounces. The increase in fabric is negligible.

This photo shows the razorback tubing and the plywood support. It is bonded in place with Hysol at the rear. The front end of the tube slips over a weldment and is bonded to a fuselage cross member.

John Pitkin
Greenville, TX

[Geowitz]

Ahh yes, I just always called it a dorsal fin. Thanks.

[cainbird]

I added one to my model 4 when I rebuilt it. I used a piece of 3/8" 4130 molly tubing and bent it and welded it in place. I dont know if it added any yaw stability or other benefits. I did it for aesthetics. There are photos in my profile.
Good Luck~Cain B

[dholly]

I did something similar on my Avid Mk-IV. A word of caution to any Avid builders considering this... the Avid flaperon counter balance weights are positioned on the flaperons so as to fit into this area with the wings folded... ie., watch your clearances... don't ask me how I know this.

[szicree]

The dorsal came standard on my Super Sport. It might be a good idea to install one so that your plane looks as up to date as possible (helps with resale).

[dginok]

I'm convinced! It shall be installed.

Thanks all,

[RV6flyer]

The razorback option applies to the model 7 SS. It is a 3 inch high dorsal fin extension to the vertical stab reaching forward and tapering to zero height at the rear of the baggage compartment.

According to the supplement in the builder's manual it "does add to the yaw stability of the aircraft."

The option is made from a 5 foot long piece of aluminum tube and a plywood rib. The parts weigh about 7 ounces. The increase in fabric is negligible.

This photo shows the razorback tubing and the plywood support. It is bonded in place with Hysol at the rear. The front end of the tube slips over a weldment and is bonded to a fuselage cross member.

John Pitkin
Greenville, TX

Were you able to bend the tube by hand?

[bbs428]

I made mine from an old, straight, knot free, 1" pine board and used the router to round off one side.
Worked out great. Attached the fore and aft ends, then pulled it down until it looked right.
Made some brackets from aluminum, pine, aero-poxy and some pop rivets.
Turned out strong and light. Covering proved to be no problem.

[bumsteer]

I didn't see it answered here and could find nothing on a search. From someone who made the razorback from aluminum, what size and temper did you use? From the photos I found looks like some used 5/8 inch and others look like 1/2. Thanks for any help.

Rick