Not much dicussion on flight testing?

[robertahegy]

Interesting about the tail wagging. I have heard some others comment about this, but I have never experienced it in my 7A. Dan C. has commented about it (wagging) and flies a 7 with the original smaller rudder. As far as having to push hard on the rudders, I have never felt it necessary to push abnormally hard to get desired rudder effect. I haven't done any hammer heads, but I do a lot of turbulence and crosswind landings. I do a lot of climbing and hiking. Perhaps my legs don't feel the strain as much. It is more rudder than typical, but I really like the response and effectiveness.

Roberta

[n468ac]

Here a link to the flight test plan we followed with our RV6A.

http://www.checca.net/Airplane/fligh...-rv6a-0360.doc

We found it on the internet and modified it to suit us.

Basically my dad and I both flew the entire test plan separately ? then compared notes.

IMO it greatly helped us explore the RV6A envelope within a structured environment.

[David-aviator]

re "The surprise that Vans had with the spin characteristics of the 7 shows that what appear to be small changes can have larger than expected affect on flight characteristics."

It is my understanding that to meet utility category spin recovery requirments, the 7 did not stop rotating quite quick enough with the short rudder. They installed a 9 rudder and it did. They then reinstalled the short rudder on the 7, at least the last time I saw the airplane, it had a short rudder. Each 7 builder was given a tall rudder kit so as to meet those spin specs.

I do not think this is a big deal. The free kit is still up on a shelf waiting to be built. My airplane is OK in any cross wind I care to fly in, plus it may even have a smidgen less drag with the short rudder, which is good and more is needed.

I don't know about tail wagging, mine seems to not wag. Maybe you-all are experiencing dutch roll.

dd

[fodrv7]

There is a good reason Van made the rudder pedal forces high.

Unlike the tailplane (and the wing) the Vertical stabilsiser is cantilevered. That is, it sticks out from the fuselage supported only from one end. This imposes much high loads on the vert stab spar and it's attachment to the fuselage. Hence the Vert Stab spar is much more beefy than the Horiz Stab spar and extends below where it attaches to the horizontal stab (and is attached to the fuselage), in order to relieve some of the cantilever effect.

To get an appreciation of the loads on the vert stab, try picking your tailplane up of the floor by holding it at the tip, instead of in the centre.

Additionally because the RVs have such a large speed range, the rudder has to be big enough to be effective at low speeds and is consequently excessively large for the job at high speeds.

Van's high rudder pedal loads discourage you from booting the rudder on the cruise.

Incidently, for this reason, most jet airliners that I flew had either a mechanical limit to rudder throw at high speed or an artificial feel system that increased the rudder loads.

Fish-tailing? Of course. Because the rudder is excessive for it's job at high speed and will respond vigorously to side gusts..... but also damp it out quikly- unlike the V tailed Bonazas. And let's not get into yaw/roll coupling and Dutch roll.
Pete.

[NeilMcLeod]

Thanks for all comments. As far as leg strength, I'm a recently competitive and still active cyclist and work out at the gym twice a week. I'm not a big guy but probably have as much leg strength as the average RV pilot. Maybe my aircraft is not typical. I'll just say I prefer more balanced contol forces between pitch yaw and roll and I have flown aircraft that are like that. If I recall correctly I can barely hold full rudder in a slip at 80 kts. I don't want to go back to the small rudder that is hanging on the wall because I do frequently spin the aircraft and do acro. In spin testing at aft cg's (aerobatic aft limit) I decided I wanted all the authority that the big rudder provides. I still have trouble recovering consistantly on heading.I haven't flown with the smaller rudder though and am curious how much difference there is. I concur that high rudder forces may be "safer" in that it may make it harder to inadvertantly spin the aircraft. I'm not sure I buy the structual argument but not being a engineer I'll defer comment there pther that I agree we don't need to be "booting" the rudder at cruise which is much above blueline. As far as a slower rotation on take off, that is a point well taken and I'll give that a try. I have a strong tendency to want to get the nose down to where I see and get stabilized in the gusty crosswinds we typicaly have here.

Neil