Not true.
The RV-6 was introduced in 1986 with a vertical stab and rudder that looked very similar to an RV-4 (and had no counterbalanced rudder).
The counterbalanced rudder wasn't introduced to the RV-6 until somewhere around 1998.
It wasn't done because of a perceived need. It was done for parts commonality (for the benefit of reduced parts inventory), and to update the RV-6 kit to benefit from some of the pre-punch advancements that had been made in newer kits.
Yep you are right. I bought and built a RV-6 kit in late 80's (drill your own holes). I finished and owned a RV-4 and currently a RV-7. The RV-6 did not come with rudder counter balanced. I got confused with my RV-7 (pre-punch) kit which does have balanced rudder. As far as reason one might think flutter. It makes sense that Van would try and make parts common with pre-punch production. A google image search of RV-4's shows some with counter balance other than Dave Anders -4. Cheers
Um, no. Many things not stock.
There is a long list I posted above. However as far as the air frame (primary structure not fairings), except for the turtle deck and rudder balance, it is at the core a stock RV-4. Of course your fantastic SDS electronic FI and E-ignition system is on the engine. Dave's installation of the SDS engine FI + EI on his RV-4 is typical, impeccable. Dave has a series of articles in Kit Plane in the last year, about developing tuned induction. His observation, optimal solution is a variable geometry induction. That would be hard to do. I'm sure Dave is thinking about it. In the meantime he is designing a fixed tuned induction based on well known wave propagation and pressure pulse data, which Cafe Foundation investigated when evaluation different exhaust for a 4-cyl Lyc (4 into 4, 4 into 2, 4 into 1, Y, cross-over). What you do in the exhaust side affects the induction of course, since they both join in the cylinder combustion chamber. There is a limited amount of tweaking you can do with normally aspirated aircraft engines. If you need or want boost you need turbo or super charger. Personally for daily flyer aircraft I'm a fan of simple and reliable, to keep prop turning making thrust.
BACK TO TOPIC, RETRACT....
Mr. Van addressed this in writing years ago why no Retract RV. Fixed gear is light, simple, and only losses a few (handful) of MPH in the up to 200 mph range, with good gear leg fairing and wheel fairings. Many retracts in the retracted position are not perfect and don't get the full drag reduction and the added weight cost speed.
CONS OF RETRACT GEAR:
- Adds Weight (negating some speed advantage)
- Complexity
- Drag in retracted position, if doors not riged perfectly (negating some of the speed advantage)
- Wheel-up landing possible by accident or malfunction
- More maintenance
If you are going to go fast, well over 200 MPH retract gear starts to pay for itself, at the expense of all the Cons above.
For people with fixed gear who want retract, I was thinking of developing a fake gear selector. The fake gear switch in the panel would have gear up and gear down locked lights with appropriate timing. When activated you would get a sound affect into intercom of gear retracting, extending and locking. If you forgot to put gear down and it detects a slow airspeed (pressure switch in pitot) you get a gear warning.....
(This is a joke but some small Part 135 charter airline in the day with a mixed fleet of fixed gear and retracts made all pilots treat all planes like retracts with checklist and verbalizing gear down (and welded). Still to this day I do "GUMPS" and state "Undercarriage" Gear DOWN, in my head.... It is my goal to never have a land gear up or ground loop in my RV. Ha ha. Batting 100 on that goal; don't get complacent.