Time has flashed by since our last posts, and a lot has happened, so I thought I'd catch up, try to answer a few questions, add a few comments and give an update. I'll imbed some with the quotes below, and finish with some pics...will take a couple posts due to photo limits in each post. Here goes...
Steve & Bob - do you plan to replace anything in the tail to reduce the elevator & rudder counter weights? Carbon fiber control surfaces?
Ralph, I have a tail kit for a 7 and an 8. I'm going to build the 7 HS and elevator, and the 8 VS and Rudder for my plane. They will incorporate a synergistic blend of strengthening mods from Ken and Eric of Team Rocket airshows near you, from Mark and Vince of the F1 Rocket Team Rocket, and from Steve. Steve will get the 8 HS and Elevator from my kit for his project, and will likely take the 8 VS and rudder that I currently have on my Super Six. We have not discussed lightening the tail counterweights or going to composite tail control surfaces....yet. The new tail will be done after initial flight test, but likely before racing in '23.
(snip)...
But.... Tapered wings, all else equal, make an airplane snap-rollier as well. (snip...)
So, you see, wing taper alone can have a big adverse effect on the behavior of an airplane at high aoa. I mention all of this with safety in mind. I muse about how much skin may have been saved over the years by Van's 10,000 or so relatively benign Hershey bar wings.
Ron
Yes, I am aware, and in the back of my mind always concerned. There is 1 degree of washout. And the taper is modest, tip chord is 55% of side-of-body chord. My lifting-surface code says it stalls first just about middle or a little outboard of the middle of the span. Should I have put in more washout? We will see. Might have to put an inboard stall strip - like Mooneys, Bonanza's, lots of others.
No matter what, it will never be as forgiving as a low aspect-ratio, untwisted rectangular wing. That is all part of performance trade-offs.
(snip...)
My objective was to publicize to those with much less background the often negative effect of taper on stall performance if not adequately compensated in either design or operation. The target is those with little knowledge in this area that may wish to duplicate and fly something similar (and why not, your wing is gorgeous!). My point is that without making allowances for the effects of a root tapered planform, stall safety characteristics may not be adequate.
Be Well,
Ron
PS: I admit I am a zealot for proper training against the sometimes fatal skidding turn to final which is part of my angst about stall behavior and thus, wing taper.
Thought I'd relate the many discussions that Steve (designer/builder) and I (builder apprentice/test pilot) have had on this topic. We have talked though expected behavior and gotchas extensively, have formulated the test plan, and have submitted it to the FAA for concurrence on test area and period. Quite a bit of slow flight/high alpha/stall work is included, and we have made allowances for test repetition, and re-test should stall strips or other devices be added to improve stall characteristics. FWIW, I share your zeal for proper approach turn execution and will fly the pattern in this new configuration more like a Glasair, Legacy or Thunder Mustang...all of which I have had the opportunity to fly and race.
This is a really fascinating thread.
Today there's an article on the Kitplanes magazine website about the F1 Rocket guys creating a new tapered wing. Apparently they're building it out of aluminum using metal techniques similar to a Vans hershey bar. It sounds like they are planning to put their version into production for Rocket kit buyers.
It's interesting to see two different tapered wing design approaches (composite vs aluminum) happening around the same time.
Would be curious to know the final specs and pros/cons of the two approaches, especially given that an RV-8 and Rocket are somewhat similar, other than the number of engine cylinders of course.
The F1 EVO currently has a tapered wing of metal construction. I've flown Mark Frederick's and it flies wonderfully. Steve can speak more eloquently about comparison between his wing and the EVO wing. Vince may may be working on a new wing for the latest iteration of the Rocket line. I'm not caught up on that tho...but I know whatever Vince and Mark do will be nice! Metal vs composite for the wing is something Steve and I discussed and decided upon at the outside of this project, so you can guess which way we think is better...or faster...or
We are getting really close. The wings are on, and final body work is being done on the wing-body fairings. There isn't very much left to do, unless we find an issue on initial systems check out (like an aileron pushrod rubbing on an internal rib, for example, it is hard to work that stuff out when the wings are in N. California and the fuselage is in Texas.) Weight and balance will be next, then ..... gulp!
This quote from Steve was as of just before Oshkosh AirVenture. We felt we were tracking for Reno '22, though the days were long, and the window was tightening. I had the opportunity to fly my good friend and airshow wingman Mercedes Eulitt's RV-7 in the Van's 50-ship, so I took a short break for that. Then during and following OSH, a few design change recommendations came to us, and, while we kept the press on a bit longer, we made the safe and conservative call not to try to take the new wings to Reno this year. I'll talk about the design changes below. We had really blasted this year, but it was the right thing to do, and after 9 years of work (due to the tyranny of distance and time available), there was no point in rushing the last month of work. We just want to do this right. When I pulled my entry, another Sport pilot offered his Legacy to me to race...if I could help him finish some prep work on it, and I...just...couldn't...say...no. So another side project intervened. Reno was fun, but we're back at it.
Before calling the Reno "knock it off", the work on paint finish, root fairings, and wing tips had progressed nicely. The initial layups for the root fairings were an experiment it fortitude for this composite apprentice, doing prep work and kitting out in the 106° day, and laying up when it cooled below 90. Doing the bottom portions, with the layers dripping hot resin or trying to fall on your face was ugly. Mornings were a little better. But the shape is what we were going for (patterned somewhat after Rocket fairings...with the aft section patterned after Steve's fave plane, the Spitfire.
The fairing was laid up in 2 sections, top and bottom, and the leading edge was scarfed in after. The fairing splits on the the upper section at the spar.
Wingtips were progressing and I had just about gotten the trailing edge closeouts done (it was farther than the first photo below. Steve had also brought out the fairings for the aileron control rod (from bellcrank to aileron).
We had also progressed well on the flap control rod connection at the flap root rib, and had the extension and retraction geometry worked out (manual flaps).
Next post will cover the design change decisions.
Cheers,
Bob