Jeepers, I can't do my mag check at 4krpm, the brakes are so weak. Stock setup, and dry disks. Probably a good thing in my case, though, as it keeps me out of trouble! JimChuk - Great panel layout! Is that an MGL FLT-2 in center?
I wondered about the small offset in my model C's fin. It's to the right, ostensibly to counter the P- factor of a left-turning prop. I presume the AOA at which this was set is that of taxiing with the original taildragger gear, but with so many possible LG variations, along with the possibility of using other engines, some driving right-turning props, and different prop diameters to boot, it makes sense that this offset was discontinued in the Mark 4. There's plenty of rudder authority in any case. Still, I'd advise putting the stiffer tailwheel spring on the side of the downward-moving blade, as this side will be where the center-of-thrust is while taxiing with the TW configuration. By the way, the use of different stiffness springs on different sides of the tailwheel is a way to eliminate shimmy, as the two sides would have different resonant frequencies. But y'all likely already knew that.
The dihedral serves a couple of functions. It helps keep the fuel flowing in turbulent air when fuel level is low, and helps stabilize the airplane in roll when stalled. As a side benefit, it allows you to cruise hands off, once trimmed up, using rudder only. The dihedral and wing twist were designed in to protect us from ourselves, i think. A Stinson -style monster fin might have also been a good call, since so many Avids get damaged in groundloops.
Good point on trim vs stick-force mitigation. My concern regarding trim setup comes from realization that elevator is not balanced - all area is behind the hingeline. If your trimtab is too small, deflection for landing approach trim may be large, or you may be unable to trim to final approach speed with CG fully forward. Of course, more trimtab span is available if what you have is insufficient. I expect that you will be o.k., as I believe the mark 4 tab is bigger than it needs to be. If your setup is successful I might just do something similar.
In answer to Chris' question: I have so far only flown with pre-mix, and have only recently put the OI system back in play. My wet plugs problem was solved with the longer-tipped plugs, thanks to Fred. One other issue relative to this question of OI vs premix is that of adequate mixing when buying avgas on a cross-country flight. Obviously, with premix, you need to know in advance how much gas you'll be buying, so you can add the oil first for better mixing. But how can you be sure it was mixed well enough? If you go to the airport cafe for lunch, maybe diffusion will sufficiently level any concentration gradients in the oil-fuel mix - or maybe not. Airplane wing tanks aren't exactly the best mixing crucible shape, wide and shallow, with far away corners. Y'all can tell me from experience if inadequate mixing has ever been a problem. Glad to hear that altitude cruise while leaned is not. On leakage past the pump while stopped: I have not observed it since the OI installation a few weeks ago. I made marks on the oil tank, and the level is holding. I'll keep an eye out for this, though. Looks like the next W&B will not be with empty oil tank. Adding oil should be allow me to get an approximate arm for oil in the tank, though. Relative to another thread, I may take a harder look at API-W3/TC ashless oils, based on Chris' favorable experience with same.
Welcome, Super-D! Like Fred says, the guys on this site are friendly, helpful, and knowledgeable. The Avid rocks, and is inexpensive (relatively speaking) to fly. You've definitely got a tiger by the tail! There is so much to learn, and so many ways to build and set up the airplane the way you want. Each of us tracks a unique path, as we come from many walks of life, ages, and even different countries. We all share a fascination with the magic of flight, and most are more interested in the flying than actually arriving somewhere. What is really great is that you can toss out a question to the group, and get back several different answers, or approaches to a particular problem that comes up. You can then pick the approach you like best, or let those ideas inspire you to your own solution!
Cowlove came up with a really neat & simple version of the hacman system using an inexpensive, small 12V diaphragm vacuum pump. These things are used in some portable medical devices, and are surprisingly easy to find online. My greyhead's carbs have no drillings for throat vacuum, to be used as a source, so the vac pump was much easier to do. I have installed his system on my engine, have used it to shut down the engine, but have not had the opportunity to check it out at altitude. Cowlove shared a pic of his instrument panel with the Catalina at 14kft! A nice side benefit is the ability to smooth out idle at any density altitude. FWIW.
Just don't ever fly into icing conditions! Maybe all that aft-body upsweep is sufficient to keep mud from the tires off of the H-tail. That would be my worry, as it's difficult if not impossible to see any contamination on the tail from the cabin.
Yes, Adelle clamps can be a real pain! So can those little spring hose clamps, as they tend to distort, then not work right (at least the cheap ones do). Correct me if this is a bad idea, but I've taken to using small cable ties to terminate fuel and oil lines instead. I pull them tight with pliers, pulling against a crescent-style adjustable wrench open just enough to pass the tail of the zip tie through.
Thanks, Nick. There are, for me, some keeper ideas here. I think I will also install a bar to extend the rudder horns to the same width as those of the tailwheel. The uneven spring pair is evidently offered as a way to mitigate shimmy, but with a left-turning prop, and hence greater on-ground P-factor thrust on the left side, I think I will break with tradition and swap the stiffer spring to the left side. I think I'll keep my Maule TW for now. Plunka-plunka-plunka!
USA35B was used on Pacers and worked well. Looks almost like a dead ringer for NACA4415, one of the most versatile of the old NACA 4-digit sections. For the H-tail, a serious consideration is mud splatter and other forms of contamination. A thin flat plate can get to a max sectional CL of 0.7. This is about as low as it goes, so it doesn't get worse with contamination, so for safety reasons aero designers just size the thin, flat-plate tail accordingly. On more modern planes they've gone to thin NACA airfoil shapes that have less aerodynamic profile drag, but they too have low enough thickness ratio that their max CLs are low enough to not degrade much with contamination. They too are sized to the max CL when badly contaminated. The CH750 kinda scares me with its tiny, thick, highly cambered H-tail. If it gets too contaminated with ice, mud, etc, and the stall CL is degraded too far, it's not inconceivable that the H-tail could be overpowered at some flap deflection, stall, and the plane suddenly noses over. Speed won't help as it increases wing nose-down moment. If the pilot is too close to the ground, or doesn't get what's happening, and pull up the flaps, he's toast.