Scudrunners

A guy once asked to do the flight testing for the removal of the aerobatic restriction on an RV6 and then do a basic aerobatic course for him.

I refused on both counts. Not knowing the build quality meant I was not going to find out the hard way some important rivets were not set properly. Even if I was comfortable removing the no aerobatic restriction I absolutely refuse to do initial aerobatic training on any model of RV.

They have the trifecta of bad from the POV of a inexperienced aerobatic pilot

1) Very light stick pitch force gradient. You can generate a lot of G very quickly with jerky stick movements

2) It is very slick and will build speed very rapidly on a downline

3) It doesn’t have a particularly fast roll rate, so if you screw up and are in a inverted downline by the time you roll it upright you are going to be going very fast

All of the above combined with a structure barely strong enough to meet the aerobatic criteria and a pretty low Vne for such a zippy airplane means that you should be an experienced aerobatic pilot before trying any aeros in this airplane

Exactly!

And it’s actually worse. For the RV-4 and RV-8 the pax is in the back seat. Any experienced aerobatic pilot is going to be very leery about moving the C of G that far back wrt doing acro dual vs solo. That’s really scary.

Not sure anyone will understand this, but if you do aerobatics in an RV, have a constant speed prop and not for the reason you think.

Colonel wrote: Sat Dec 03, 2022 6:15 pm To get really big horsepower out of a Lyc 540 you either have to spin up the RPM

Right, winding up the RPM a bunch is an option too. I’ve heard guys will run O-200s in F1 racers at 3500rpm and I feel like I picked up somewhere that an O-360 will hang together at that speed too though an un-drilled crank might be needed. You would know better than I do though, these things are closer to your circle. Do they even make fixed pitch/helicopter cranks for 540s?

RPM is not a problem for the engine. It is a problem for the prop when you are direct-drive.

The Reno guys are running their blades super-sonic which is incredibly trick. Most of us keep
the prop tips to a max of 0.9 mach. Above that, thrust decreases. Unless you're a warlock.

PS first thing I would look for at 3500+ RPM is valve float. You might need more valve spring and at that point a roller lifter is a requirement. Flat tappets are not going to tolerate stronger valve springs.

You might eventually get rid of the hydraulic lifters if they pump up.

A guy I know spent a few months of quality time in the local hospital after the surgeons cleaned out the fastener section in the hospital parts stores. He was racing his F1 with the O200 turning up around 3500 RPM

The engine suffered a total instantaneous traumatic disassembly at not a good time and place……

Reno is a bit like the Isle of Man TT. Extremely high risk must be accepted to participate.

Not what normal people do.

Fun fact: people say health insurance is expensive here. No, it isn’t. I pay far more for life insurance. 20x base.

PS I remember seeing a really weird failure of an underworked O-200. Clamshell cracked.

No idea if it was an ancient casting flaw that finally let go, or if the casting crystallized over the decades. I think you need to anneal them or something? Not a metallurgist - I always let my Dad worry about that.

Colonel wrote: Thu Dec 08, 2022 1:00 am Reno is a bit like the Isle of Man TT. Extremely high risk must be accepted to participate.

Not what normal people do.

I would love to race at Reno at some point. Presently I don’t want it more than what I’m already doing but if I win the lottery, look out world!

Just a bit or trivia. Back in the 70s when some folks in Columbia were do ing international cargo flights at twice the MCTOW, they tweaked the engines on the Navajos to take off….”once…”at about 76” MP.

Apparently, according to the folks at Flight Safety, was not particularly difficult to do, but I have forgotten the details.

Bob Piche - Azores Glider - could probably fill you in on that.

I’m amazed the turbocharger on the Ho large enough to create that much boost down low.

I hope they used Methanol injection.