Vance, One has to wonder if the prop's design twist distribution missed the sweet spot for our airplane/engine combo. I'm thinking it may be too flat, if the smaller engines used in single-place planes turn their props faster, or these birds fly slower. Too little twist would tend to unload sections in the lower radii in cruise, making it easier to overspeed your engine, since their contributions to torque would be less. Just a thought. Slow airplanes, like Quicksilver, require flatter props, while faster airplanes demand twistier props. One fact most people are not aware of is that a given airfoil shape will have a significantly higher AOA at stall (and CLx) on a propeller than on a wing, due to rotational effects. So it may be better to have a little too much blade twist than to have too little, especially in cruise. Flatter props will, of course, climb better.
Efil01 did a brilliant job combining the best of both wing types. The problem is nesting the next smaller tubing inside the existing spars since typically this doesn't work with 1/8" diameter steps and wall thickness greater than 0.058". However, by going to the next larger tubing size, for the span extension, and 0.058" wall thickness, you could extend the span out to that of the STOL version. Bending moment at the joint would be well below that at the strut attachment, so it's safe structurally.
Gauntlet thrown down. Why no takers? Is it because certain positions are idefensible via reason? As a small-group animal for tens of millions of years, only trying to live in mega-society for a few thousand, our instincts are to try to scale the default small-group paradigm up to the larger scales. Just as altruism works inside the implicit accountability of the small group, but seems to fail in the larger societal scales, so does the paradigm itself, as it leads to top-down forms, where corruption sets in, and abuses follow. This does not optimize happiness & life satisfaction. Want Big Daddy to take care of you cradle-to-grave? Or do you see more possibility in watching out for yourself? We all have the brains to pull this off; we just need to be prudent, i.e. exercise wisdom, either garnished from our own life experience, or learned from a trusted elder. BTW, I define wisdom as the ability to avoid unforseen negative consequences. So what I believe conservatives are saying is: Don't give up your all-important, God-given liberties for goodies like free healthcare or free education, which for their own reasons will rot on the vine. Eschew the top-down nanny-state that will eventually turn us into dummies, then inevitably begin abusing us, and embrace instead your ability to make your own way as an individual! In the end we will all be happier and more proud of our accomplishments in life. The Founders developed something very special, and anyone who advocates ditching it is, in my mind, a damn fool. But remember: It is a counterinstinctive intellectual construct. As such it is like an arrow trying to fly backwards; unstable vis-a-vis our everpresent hard-wired instincts. We all, by our reason and wisdom, bear responsibility for actively keeping it alive. It goes without saying that: "When an optimum is reached, all change is negative."
Yeah, that was my original thought: that toe-in would work to increase drag on the more forward tire relative to the direction of the plane's momentum, thus working to help align the plane with its direction of travel, so I couldn't understand how toe-out could be beneficial. Now I get why this could be wrong, and could make a swerve worse. Thanks for the explanation! I think I'll keep it neutral just the same. I imagine tires last a lot longer on grass - maybe forever! (Jk) How many tarmac landings is a Carlisle good for anyways?
With gps nav, it should be easy to stay out of classes B & C airspace anyway, at least out here in the stix. Real-time weather is a good reason to consider ADSB-in, though. Homebilder's Help describes a cheap kit for same.
So the big mystery to me is: why more thoughtful liberals are so reluctant to eschew the anti-logic of their nutcase radical leftist "leaders"? I recognize the raw power and pervasiveness of the left-wing propaganda machine, and understand the need for younger folks to fit in to some social context - have a "tribe" so-to-speak, which also tends to support homogeneity of opinion, but there's always the closet, if one lacks the boldness to be different. The voting booth is a private place. I venture that most liberals just want bigger government & more services, and perhaps better protection of the environment, but not the total destruction of our system of government, so why can't they see that they have much more in the way of shared values with us conservatives? It seems they'd follow their insane lefty leaders off of a cliff! Maybe life in the city provides so much stimulation that people have no time to think things through. In the country, it's mercifully different. OMG, another frightening thought! What if the only thing slowing down this seemingly inexorable march towards totalitarianism is the baby boomer bulge?
Appreciate the offer, Vance. Maybe there is a screw-top NGK plug BPR8E (or something) that would work with those caps. Have you ordered the new plugs yet? I went to a shop that sells chainsaws and offroad vehicles and bought their last 2 BPR8ES solid-top plugs. Paid too much, but had a hard time finding them in the auto parts stores. I'm about 4 gallons of premix away from putting on your OI pump! Again thanks for that!
Dude, I did my own pre-purchase inspection. You can too. These birds are simple but elegant in their design, and stout. My advice, FWIW, is to read up and learn as much as you can on this site and others. Take stock of your own competencies: engine mechanical stuff, electrical, welding, fabric work, etc., then look out for problems on the bird that align with your weaknesses. On Avids, the flaperon hangars are a weak point, as they are essentially hi-grade plywood painted over with dope. But there are 5 per side (fewer on the speedwing versions). If one or more is broken or weak, some complex wood-and fabric work would be in your future. All the engine stuff is pricey, so pay good attention to that being correct. If possible take a look into the exhaust ports for scuffing on the cylinder walls, piston carbon or lead fowling, etc. On this site the guys are awesome and knowledgeable, and will welcome and advise you along the way! And what a journey it is! Good luck, and welcome!
Just a question: Do you carry extra plugs just so you can easily swap in clean ones? These one-piece items don't wear out (well, they do but only very slowly), but they do crud up if engine conditions aren't right. One could just as well carry the wherewithall to clean & maybe gap them.
Thanks, guys! True, I don't fly often enough! Last time up it felt chilly! Does NGK make a BR8ES-P plug? I'm so glad there's a simple answer out there! I will definitely pursue this. Thanks, Fred, for going the extra mile (or couple of km).
So here's another con. Of course it's way more convenient when stopping for gas on a cross-country, as you don't have to guess how much petrol you're going to buy, then add the appropriate amount of oil to the gas tank before filling the tanks, but here's another reason: If you do any cruising at high altitude, such as if you're going over high or difficult terrain, you will likely want a leaning system as well, so your engine is not running overly rich on fuel, reducing your range. However, running leaned out at altitude, and likely at higher RPM, with premix, less gas means less lubrication, whereas with the oil injection you get the same oil flow, even though you're burning less fuel. The OI system only responds to two things: engine speed (RPMs) and throttle position. My bird was set up for premix, and I am going back to the OI system, principally for these two reasons. Reason 3: every time I go to fly, I have to pull a couple of plugs, and shake & wipe them clear of oil so my engine will start. With the OI system putting proportionally less oil in at idle, maybe this inconvenience will be mitigated.
The only correct way to revert to premix is to disable the oil injection pump. Some people completely remove it and fabricate a plate to cover the opening, but most simply remove the plastic gear that drives the pump, then put the pump back on. The pump itself mounts below and between the two carburetors (above if we're talking Kitfox, with the upright engine). Here's a pic of the (disabled) pump from below, on my Avid with the inverted (plugs-down) engine. That squarish metal thing on the upper left is the bottom view of the aft carburetor's float bowl. The white plastic gear on the oil injection pump shaft won't fit thru the hole where the pump mounts, but the housings are layered, and removing the next layer allows access. All this engine stuff is pricey, so hopefully the seller has the pump and that white plastic gear, as well as the Bowden cable to tie in to throttle position! The pump has two "banjo" (shaped) fittings which connect via small plastic line to the injection ports. Maybe the banjo fittings are more visible on the second pic. With typical strong pressure pulsations of 70-100 cycles per second at cruise there's no need to actually spray the oil at high pressure. I think it just dribbles in, but gets essentially atomized by the pulsations. Visible on the upper right is the oil inlet connector tube, blocked off here with some red plastic.
Hi Y'all, Every time I go to fly my Avid I have to pull a couple of plugs, then shake and wipe away excess oil, then reinstall, otherwise I can't easily get the engine to start. I have a grey head 582, and am still burning down my premix before reinstalling the OI system. Do we all share this misery? Will the lower oil flow when idling with the OI system mitigate this problem? I have the pull starter, so really feel it when the engine won't start. BTW, I shut down by turning the fuel valve to off, then waiting the couple of minutes for the engine to shudder to a stop.
Brilliant work on the wings! On the cowl bulge, I was contemplating making one, but find myself pulling a spark plug or two to clear off oil almost every time I fly, as otherwise I have a hard time hand-starting the engine. In my view this is the chief disadvantage of the inverted engine, at least burning premix. I now am just going to leave that hole in my cowl to allow front-cylinder spark plug access without cowl removal. I agree that the gap between flaperon leading edge and wing trailing edge is not optimal aerodynamically, but may be necessary for folding.
One benefit of the bellyrad is the aerodynamic shielding of those draggy round landing gear legs just behind, and tucked up against the belly. I think that shielding helps reduce the penalty for just sticking that rad out in the stream, uncowled. Of course, nothing says that cowling the rad will automatically reduce drag - that would require flight test data and careful aero design based on same, with some design iteration. Another thought for improving cooling would be some kind of extended gill flap to help suck air thru the radiator. That option, however, is inconsistent with the current bellyrad, as the rad will kill the momentum in that near-wall flow, so deflecting it away to create suction over the current in-cowl radiator's air exit would likely be futile. Here is a great opportunity for a variable cowl flap, which could be closed down in cold cruise conditions to reduce drag!
It's more fun just putting around the sky anyways, unless you're actually trying to get somewhere. You Alaska flyers amaze me. I must still be a little shy of trusting the 582 like you guys do. Hey, I'm still trying to nail down my landings.
Based on the sandbag test in the Avid literature, the maneuvering speed Va should be 104 mph. Why they list something lower as never-exceed speed I don't understand. That Va I quoted is equivalent airspeed, or EAS. Errors in the static pressure measurement could easily cause your ASI to read high or low, though. Change AOA, open or close your vents? All act to bugger the cabin pressure, which is used as the static pressure. I'm tempted to build a static cone or other device to try to get a decent static pressure measurement then calibrate the ASI. The total, or ram pressure is relatively easy to measure accurately. The static is difficult to get right.