Posted Sunday, December 31, 2006 @ 10:53 PM
Hello Steve, Folks,
Section 2.2 of the RF4D Flight Manual quotes manoeuvring speed (they call it Vp) as 124 mph/ 107 kt.
I use knots, so if you fly mph you'll have to convert by multiplying by 1.15.
I fitted this 3M Mylar gap seal tape (with the PTFE anti-chafe tape on the ailerons), but not having any better recommendations, I used the self-adhesive tape with the zig-zag leading edges. It came from Germany. I stored it rolled up for over a year, and it glued on quick and sweet as anything. That was in 2005, and they're still on there over 250 aerobatic hours later. I pre-flight it every day, and have not seen any sign of it peeling off. I did clean the area with acetone first of course. I have since incorporated exactly the same mod on my British (red) RF4, and it is approved by the LAA.
By how much should you reduce Va? By as much as you think appropriate. I really don't know, but I ensure I do not have full aileron above 100 knots. This tape has very significantly increased my roll rate -- nearly doubled it, but that will increase torsion on the whole wing. Do NOT roll and pull at the same time, the combined rolling and pulling loads could easily tear off a wing. I would suggest you get familiar with the standard airplane first, before adding the tape. Rob Dorsey, David Perrin, the Unipart Duo and the Skyhawks (among many others) all flew upward vertical quarter rolls in standard airplanes.
Previously I could fly a quarter vertical roll up and down, but with these seals I can almost fly a half roll each way with a humpty-bump flop over the top. Be very careful going downhill, you can easily exceed Vne if you don't start at stall speed and pull at least 4g to recover. Start by rolling through a small angle, with the throttle closed, and gradually increase the angle. Then you can transition to the full-power recovery.
Going upwards, be prepared for a tailslide. If the airplane slows to a halt pointing upwards, I find it best to hold the stick rigid in the central position with both hands (jam your elbows) and clamp your feet hard on the pedals, although some folk suggest putting everything over into one corner. Whatever version you use, the important thing is not to let the controls whack against their stops as you slide backwards through the air.
And start all this sort of experimentaion high up (5,000 feet agl) and over the sea or the desert. These airframes are more than forty years old, and you know how easily a dry old twig snaps. You don't want a heavy old Volkswagen engine falling on somebody's head... or your heavy old (or young) body.
Where these seals really help is in flying a clean Immelmann (roll-off-the-top). Pulling into a loop at 120 kt, even if you pull 4.5g all the way around (so the loop won't be circular) you're lucky if you're still doing 65-70 at the top when you have to make that half-roll. You're way below Va, so you know you can whack on full aileron, with rudder to taste, and get a much cleaner half-roll without sagging too much.
The best book on aerobatics, by far, is Alan Cassidy's Better Aerobatics. My well-thumbed copy is down at the hangar right now, but I guess we'll start an aerobatics section, and I'll put his address in there.
Happy Fournicating, Bob
[Edit by Bob Grimstead on Tuesday, November 18, 2008 @ 00:00 AM]
[Edit by Bob Grimstead on Tuesday, November 18, 2008 @ 00:06 AM]
[Edit by Bob Grimstead on Tuesday, November 18, 2008 @ 00:09 AM]
[Edit by Bob Grimstead on Friday, June 10, 2011 @ 06:17 AM]