Oh, sorry, it’s been down for a while as I was planning on moving from Joomla to Wordpress, I just didn’t have the energy to redo the site…
I’ll get around to it once my nerves have settled… :)
(from the light pitch forces you mean? :))
Yes… still shaking over here…
I dare say it is the lighter stick forces with the RV-6 than you may be used to.
But, RV-6s can come out with a CofG towards the aft limit – especially if it has a light engine and prop combination. I remember the build manual saying to keep the back end as light as possible.
The one you flew, you say had an IO-320 and a fixed pitch prop. The O-320 is the lightest engine intended to be fitted into the -6. Was it a wooden prop or metal? Also, if it has had a lightweight starter fitted now that will make a difference as will having a lightweight alternator, electronic ignition etc etc. Does it have a heavier tailwheel than standard?
Fuel, people and baggage take the CofG aft and they all alter the feel of the aircraft.
My (co-owned) RV-6 had (still has) an (AE)IO-360-A1A 200hp angle valve Lycoming and a metal Hartzell CS prop. We did have a lightweight starter and electronic ignition. With this relatively heavy firewall forward installation, we moved the battery into the baggage bay in accordance with the build manual options.
Most people that flew ours would be climbing at 1500FPM when trying to do a level turn as they applied the stick force they were used to in Cessnas and Pipers. The only person who flew it accurately first time was the guy we eventually sold it to – he had a bit of a natural feel for high performance machinery being an ex three times British Superbike champion…!
The RV-7 was designed to increase the max weight, use the bigger angle valve engine as standard etc etc. I never heard of it being done because of GofG issues with the RV-6.
Interesting about the three times British Superbike Champion… People lime that can make you feel a bit useless 
If stick displacement is what you want, you’d need to lengthen the stick. If the force was too low, then you’d shorten the stick. Obviously you can’t Increase displacement and force simultaneously by modifying the stick length.
Every machine I own except my certified planes (particularly my motorcycles) has been through a development process to get the handling how I like it. On some of those it’s been a long development process. All I’ve done on certified planes is move the CG within certified limits. One the nice things about Experimental Category planes is doing the same thing I would otherwise do on virtually any vehicle. Re certified planes, I’m still interested in doing an aileron spade STC for Luscombes some day – they have heavy ailerons combined with light pitch and very light rudder. I think you might be able to sell the STC and make literally hundreds in pure profit after many months of effort 
The anti-servo tab on the Cherokee doesn’t just add a bit of extra centering force, it adds all the centering force and without it the plane would be unflyable – that’s how flying tail elevators work. They were a favorite of John Thorp (who designed the controls on the Cherokee) partly because they are tuneable by changing the linkage – although I get the feeling it’s hard to make them perfect. My other plane (not a Cherokee) has a very powerful, fairly light and somewhat nonlinear flying tail elevator, but it’s set up with a lot of stick displacement so as long as you don’t fly purely by force gradient it’s OK. Not much to be done about that one, flying tails often feel a bit weird.
It’s pointing out the obvious that diddling with controls requires care. A local guy put a moveable pitch trim tab on the tail of his canard Q2 (two seat Quickie) years ago, with the intent of adding a ‘knob’ to counter the nose down trim change on that type when entering rain. Unfortunately he put the pivot too far back and it was unstable, sending him hard nose down into the ground on the first flight… which killed him. On the other hand doing things with hardware that require individual care to avoid individual consequences is the best thing in life for some.
Thanks for input!
This one has a Catto prop (composite?) and a slightly larger sealed tailwheel than standard IIRC.
The CG moved aft by about 1 cm when he replaced the starter so it seems to me that it’s pretty tail heavy already to begin with.
I can imagine that pilots may have trouble flying it initially considering how sensitive it is. My own muscle-to-brain feedback loop appears fast enough that it managed to detect the situation and not over control, i.e. I avoided embarrassing climbs or descents. :)
On the plus side, once we got slowed a little it really flew nicely and this one has the smoothest running 320 I’ve ever encountered.
If stick displacement is what you want, you’d need to lengthen the stick. If the force was too low, then you’d shorten the stick. Obviously you can’t Increase displacement and force simultaneously by modifying the stick length.
Yes, shortening the stick in this case would require more force so would reduce the risk of over controlling, which was the initial thought. Just holding the stick close to the base made it a bit better (in my view).
I’d like more displacement, but that would certainly require serious modification and is not something I would consider doing on my own..
I think this is exclusively a getting used to thing. You soon learn to think in terms of aircraft movement and g-forces instead of control forces like you do with a Cessna. If you didn’t, nobody would be able to fly RC airplanes. That said, if you think the aircraft has a COG issue, you should weigh it and fix it.
I’m on my fourth RV and never experienced anything like that (admittedly no RV-6). I would compare then to a Chipmunk ( without being underpowered).
I think Aerofurb’s comment could be relevant. An aft CG is quite likely with a light engine prop combination and full passenger payload.
Some owners install heavy propeller crush plates or Landoll rings on the flywheel to try to restore a forward CG.
Another possibility is too large a trailing edge radius on the elevator. The plans call for a 1/8" (3mm) radius. Too large a radius can cause a vortex interaction that has the effect of destabilising the pitch sensitivity. You can make a trailing edge squeezer with a couple of planks and some door hinges.
Another possibility is too large a trailing edge radius on the elevator.
Ahh, yes. I made sure mine are squeezed hard. But this also has some adverse affect, they could crack, particularly on the -4 with slightly thinner skin (I think the -4 and -6 has identical tail). Thicker skin was available as an option. All this is (semi) clearly pointed out in the manual though.
