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American ultralights can have retractable wheels if they're amphibious. Or a glider. They can also be heavier if you have a parachute. I think 17lbs is allocated to a parachute. But most are under 10. Oh, and an important note. Most ultralights "aren't." The affordaplane builds up almost 50lbs heavy. The legal eagle doesn't easily make it under weight. And a variety of others are just barely scraping by. Nerobro fucked around with this message at 23:02 on Apr 3, 2012 |
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Apr 3, 2012 23:00
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What's the lifespan of a canopy?
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Apr 16, 2012 07:22
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Slight cub infestation? That is massive. I'd call an exterminator. Or at least a Bearcat to clean the joint up. On plane news... I bought a house. It will be about a month before it's totally "in my hands." (203k HUD stuff...) I'm excited. I"m also seeking opinions on the KR-1.
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May 6, 2012 06:34
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I own a house now. :-) And I am negotiating some aircraft materials. woohoo!
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May 21, 2012 23:48
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hayden. posted:How safe are these ultralights? They look awesome as hell and I've always wanted to get my PPL, but maybe this would be a cheaper alternative. In a large part pretty safe. The idea is that they're draggy enough to never get going that fast, and in full stall they're falling at a non lethal airspeed. Really, they're as safe as you want to be. If you treat them as a "real airplane" they're as safe as a real airplane. If you treat it like a lawnmower... well you can expect some lawnmower ish things to happen.
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Jun 30, 2012 00:36
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I've always said that there are model airplanes that could carry a person. Now you're using model parts to carry you. :-)
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Jul 14, 2012 05:21
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It would seem money is starting to go my way. I think I can order aluminum this week. that means I also need to build some work tables and start doing an ever loving butt-load of layout.
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Jul 16, 2012 00:49
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babyeatingpsychopath posted:Here's a question I haven't seen addressed at all: It's only "sorta" crazy talk. There's a lot to consider though. Piston speed directly relates to engine life. Most motorcycles (the Hayabusa included) run with some fairly high piston speeds. While the base motor might make the power, and do it light enough, it's durability is in question. Second, sustained power levels. Motorcycle engines, for the most part, are designed for intermittent power. You'd need to look at adding an oil cooler, and potentially piston squirters. You'd also need to consider cylinder head heat soak. If the cylinder head can't extract the heat, you'll end up melting exhaust valves. Changing the gears isn't a very useful trick. At most you'd need two. changing prop pitch is the air going equivalent. To give an idea of why it's not so useful. If an airplane is sitting still, on the ground, and at full throttle, you can expect only a 200rpm drop versus cruise rpm. Also, with changing gears, pilot workload is an issue. So you don't want to do anything that's gonna stress a guy out while flying. More features is not more better! Propellers are heavy. And they're springy. This means the forces that come back from the propeller are difficult to manage. (This is also why wood props are popular. They self dampen somewhat.) Each gear interface, is a place where all the loads of the engine are placed on some very small gear teeth. This leads to a catastrophic failure mode. Namely munched gearbox! The single plug ignition is "something" of a concern. But there are plenty of airplanes out there there fly with single plugs. Including all auto conversions. You can set up redundant ignitions without redundant plugs. It wouldn't bother me much. The fuel injection system is a problem. The Hayabusa computer doesn't know what to do with changing altitude. Put in a new controller. Older bikes, with CV carbs are at an advantage there. CV carbs are altitude compensating! Which means you remove a control for the pilot. The Rotax 912 has CV carbs, so that's even certifiable. After a lot of thought on the subject. I concluded that the only way to use a motorcycle engine in an airplane, was to cut off the gearbox. You get several advantages there. First, lower base weight. (though you'll need to add a reduction gear...) Second, you can use a belt type reduction unit, which addresses the resonance issues. Third, you end up with an excuse to build a proper sump, potentially with a lot of cooling area, removing the need for separate oil cooler piping and the associated points of failure. The motors from motorcycles that most easily convert to airplane use are the bmw boxer twins, the honda flat fours and sixes, and harleys. All of those motors are separate crank and gearbox engines. And most of them run conventional car speeds. So you're not really finding more power. I suppose you could fly on a MotoGuzzi... but I have something deeply against using italian motors for anything that's life dependent. All of that said..... You have the same concerns with a car engine. And car engines fly all the time too.
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Jul 30, 2012 15:28
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Ferris Bueller posted:*Which is kinda funny that so many experimental builders are not actually experimenting, but I understand where they are coming from. Yes I realize that many guys are experimenting as well, and I'm not trying to dig anyone at all who has the balls/whatever to build their own airplane, tried and true design or drawing it up yourself. I have had this argument with myself a few times. And.. after hanging out on enough builder forums, I've determined that even though you fly a "RV6" or "A Hummelbird" or whatever.. the chances of your plane matching the performance of another plane are so slim that you might as well be flying a one off. That's what makes a certified plane so expensive. Building the planes to the EXACT SAME STANDARD so that the same numbers can be used from plane to plane. the RV's get close... But most homebuilts tend to be different in some significant fashion from the plans, or even the kit. Sadly, most builders don't thoroughly test their planes to properly determine what their flight envelope really is. I'm currently on the KRnet, and the DA-2 mailing lists. I was kicked off the Affordaplane mailing list. ;-)
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Jul 30, 2012 21:19
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so.. I'm trying to buy 2024 t3 aluminum from somewhere OTHER than aircraft spruce. .025 and .040
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Aug 22, 2012 03:29
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zharmad posted:I've had affordaplane plans for a while, and plan on building one once I get back in the US. My wife has concerns about my safety while flying, even though I plan on taking flying lessons before I ever try flying on my own. Does anyone have a whole-aircraft parachute or have any experience and recomendations for one? You just stopped my heart. My recomendation, is buy a parachute, but don't build an affordaplane. The Affordaplane is a flawed design. The design is more so flawed because nobody has actually characterized it's flight. Built to plans, it will be more than 75lbs overweight. That's 30%! Your wife SHOULD have concerns. Balistic parachutes are a good plan in general. There's no reason you can't build a plane that's "affordaplane shaped." But you should spend some time with a calculator and re-do all of the dimensioning. You can save THIRTY POUNDS of fuselage weight, and still retain strength to support 10g's of loading. ... After accounting for the 60% derating for aluminum in high vibration environments. I made and maintain (heh) http://theaffordaplaneresource.blogspot.com/ Lets say I put a lot of thought into my opinion.
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Aug 22, 2012 04:44
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And here we are a few hours later. So.. If you are set on the affordaplane, I can send you my notes on it. The changes are .. extensive.
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Aug 22, 2012 15:25
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zharmad posted:Well, I haven't bought any material yet, but was looking for a project to start over this winter. I'm not married to the affordaplane at all, but I expect to have about 90 days that I'm not working to devote to the project. Is it worth the time to re-work the plans or is there a better plan out there I could get? Well, to be really silly. You can buy an off the shelf ultralight. Brand new, for $10k. The legal eagle is a better plane. And it can be built under weight. The ultra baby can be done as well, and it shows the designers work, so you know the math is right. The Sky Pup is definitely 90 day able, but it's not a 3 axis ship. I really like the fischer flying products airplanes.
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Aug 23, 2012 06:15
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http://www.n56ml.com/n981jf/ Please tell me not to build a KR? Please?
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Aug 24, 2012 05:20
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helno posted:Changing your mind about the DA2A? Not really. Just that KR-2 is pretty as hell, and makes almost everything on the market look bad. Getting my hands on .025 and .040 alclad 2024 t3 seems to be harder than I was expecting. Any suggestions that don't have spruce in the name?
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Aug 24, 2012 14:52
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First off, since you're getting your license, why limit yourself to a ultralight? There are a lot of small, easy to build airplanes out there. Which opens your options to all sorts of "normal" engines. Is the engine the only thing that is really keeping you on the legal eagle? My only "problem" with the legal eagle, is that you need to learn to weld, as well as woodwork. A texas parasol is a very similar rig, but is all wood, simplifying life quite a bit.
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Apr 10, 2013 06:22
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charliemonster42 posted:My biggest concerns with doing a full scale airplane is time and money. I don't know how readily I'd be able to commit 3 years to a project like that. I've looked at a few full size kits, like Sonexes and RVs and the like, and would love to do one, but the level of involvement with a kit like that is orders of magnitude bigger. Ultralights, and "full scale" airplanes are very close in size. In fact, for single seaters, ultralights tend to be much, much bigger than "full scale" airplanes. For example, a KR-1 Length 12' 9" Wing Span 17' 0" Total Wing Area 62 sq. ft. Cruise 180mph Lets compare that to a Lazair: Length: 13 ft (3.96 m) Wingspan: 36 ft 4 in (11.1 m) Wing area: 143 sq ft (13.3 mē) Cruise 40mph The lazair is almost twice as big! Lets try another. The Legal Eagle: Length: 13 ft 0 in (3.96 m) Wingspan: 23 ft 6 in (7.16 m) Wing area: 107 sq ft (9.9 m2) Cruise speed: 50mph Lets get back to "conventional" aircraft. Those that don't have the ultralight tag. I'm going to stick wtih single seaters to keep things even. Rutan Q1 "Quickie" Wingspan 17 ft 9 in Length 17 ft 5 in Cruise 120mph FRED Wing span: 22 ft 6 in (6.86 m) Wing area: 111 sq ft (10.32 sq m) Length: 16 ft (4.88 m) Cruise: 71mph RV3 Length: 19 ft 0 in (5.85 m) Wingspan: 19 ft 11in (6.12 m) Cruise 170-190mph So, why a "legal" plane versus an ultralight? Ultralights live in a very narrow range of airspeeds. And in a very narrow range of weight loading. Ultralights can't fly around populated areas. Ultralights aren't really welcome in controlled airspace. Ultralights have quite short durations. Building a plane that fits into the narrow little corner of the law that is "ultralight" is just that. A plane that exists in a narrow little corner of the law. If you don't need to live in that little corner, don't. Building an ultralight means leaving a lot of the fun stuff at home. A decent guage cluster. Comforts, and even some safety systems. You don't see carb heat on ultralights, nor cabin heat. You also almost never see flaps, and things that you should want to use to keep your skills up. "Real" airplanes give you more room to fudge. You can leave things a little heavier and you will still get a decent plane. "Real" planes also are smaller, which means there's less material to buy, and usually cheaper materials to buy. They also tend to use normal covering techniques, and normal materials, so you can get normal advice from normal airplane people. Not that I'd personally use normal materials or covering... I'm just saying.. you can. :-) Now, you asked about the plane getting checked. As far as I know, nobody gets checked. But, if you crash, and there are legal proceedings, your rig WILL get checked, and then you could be up the creek. Operating an unregistered aircraft, that sort of thing. And no insurance will want to touch you ever again. Why do you think an airplane will take you three years to build? why do you think a Legal Eagle will take much less time than say.. a Cub clone? (they are of about equal complexity.) Something like a FRED assembles very quickly. So can a KR-1. I went through the same thing. I didn't think I could afford to actually get a pilots license. when I discovered that it was going to be a reality, I did a careful check of myself and what my desires were. Building a ultralight just didn't make any sense once I knew a real license was in reach. Recently I read through all of bob hoovers blog. I picked up all the really choice stuff on building an airplane on the cheap. http://realtinker.blogspot.com/2013/04/cheap-aircraft-building-techniques.html Helo: no offence eh? :-) Ninja Edit: And somehow i got through a post without mentioning a DA-2 or a Hummelbird. Amazing.
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Apr 11, 2013 05:40
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Sagebrush posted:My understanding of why rotary engines seemed to be a good idea in planes is that it came down to two things: (1) the inherent smoothness of the design, and (2) with iron rotors in an aluminum housing (vs. aluminum pistons in an aluminum or iron housing) they can't seize from overheating. You can also run a rotary engine with pre-mixed oil like a two-stroke, which saves you from having the oiling system as a point of failure. That's because nobody "really" seems to understand wankels. (I avoid the term rotary because that can mean a different kind of engine. See: Gnome rotary) Wankels really don't seize. (Modern cylinders and piston rings don't either..) But they do start detonating. Instead of seizing, the hot cylinder walls start to bulge, and you lose compression. And you lose apex seals. Or, if you manage to keep the seals around, then they start detonating, and really bad things happen. Like busted center section bearings, and more, blown out seals. The big advantage with a wankel, is it's size. They're downright tiny. However, they aren't a light as people seem to think they are. The need to have oil in the fuel is a sign of a design FAULT, not a design advantage. You can run a little oil in normal piston engines and it helps with ring life. Much as it helps with apex seal lift. The fundamental problem with Wankels is cooling. Piston engines have several methods for cooling pistons. There's the incoming air charge, there's air under the piston, there's contact with the cylinder walls, there's heat conduction through the rings, there's oil squirters to cool the bottoms of the pistons... There's NOTHING to cool apex seals, other than contact with the cylinder wall. And then they don't get any oil. The only way to carry significant heat from the rotor, is through oil. (or, in the case of the Hercules motorcycle, intake air... It ran the intake air through the rotor.) Oil management within the rotor isn't easy. There's also no easy way to increase the displacement of a Wankel. Rebuilding one is not far removed from building a new engine, because you can't refinish the cases. And, from what I've seen of installed weights, the weight of a Wankel is comparable to whatever horsepower engine you intended to run in the first place. ... I am a fan of these motors.... I've got several books on their history, and the math involved in them is inspiring. So is the story of making them survive. And the different engine case arrangements. (thing spinning block, with a straight crankshaft...)
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Jul 23, 2013 03:04
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When did you leave? I was there on saturday.
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Aug 7, 2013 14:41
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kastein posted:What are people using for PSRUs on Subaru engines? First off, what plane do you have in mind? I would recommend avoiding PSRU's. And that horsepower level for a subaru seems.. very, very high. I strongly suspect you'll run into head cooling issues at that sort of power level. I can go into the whole explanation of why "romp all day at 250hp" isn't the same as "flying at 200hp" if you'd like. So, to avoid the PSRU issue, feel free to run boost. Build for torque. Spin a multi blade propellor a little faster, and keep the blades shorter. You can find a lot of usable power without going to 6000rpm. Take a look at the people flying Corvairs. If you're dead set on trying to get 250hp from a subaru for any useful length of time, and require the PSRU, building your own is not an insurmountable task. I'd look at this guys documentation, http://www.zenith.aero/profile/Ben He's got a v8 engine driving a (mostly homemade) PSRU. We can also discuss what causes crank, and PSRU failure. :-)
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Feb 18, 2014 19:01
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1900 foot pounds isn't enough. At least not without some very, very, very, serious torsional damping in place. Hardening has it's own share of issues, beacause with hardening, comes brittlenss. Propellers are big springs. They resonate. If you reach the right rpm, where the power impulses are anywhere near the same frequency as the prop is rotating, you can build some massive forces in fractions of a second. The big advantage of having a zero lash drivetrain, is as those forces build up, they never unload the mechanical bits. The hammering action of teeth on each other causes even mild resonances to weaken and remove teeth rather quickly. Piston sprayers shouldn't be left on the table, don't add those as an upgrade, do them the first time. I can't say it enough, the sort of operation that airplane engines sustain, isn't equaled anywhere else that most people have experience with. Another thing to look at, is the Subaru engines aren't all that light. A good PSRU isn't going to be light either. If you really want 200hp, there are other engines that can do 200hp, without needing a massive array of associated support devices. For example, the ford SHO v8, is making 210hp at 4800rpm. And is a mere 390lbs. And then there's the classic inverted oldsmobile V8 in the wittman planes. You can check this for installed weights of subarus. http://www.sdsefi.com/air51.htm
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Feb 18, 2014 19:45
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MrYenko posted:That thing looks like what you'd get if you asked a scale modeler with zero engineering knowledge to build an airplane. I read this as if you were talking about someone who builds flying model planes. Instead of scale models that sit in dioramas. The first interpretation borders on insulting. :-) A lot of r/c people don't understand engineering, but somehow do grasp "what seems right" and they make planes that fly very well.
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Feb 26, 2014 17:38
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well.. I'm sure there's a lot of good wood there. "aircraft quality" wood is a matter of selection, more than "as delivered" state. But geeze, that pile doesn't look good. I love how he thinks his 1/10 model which was 800g, will be 750kg once scaled up.
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Feb 27, 2014 18:47
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You need to buy that thing just to fix everything that's wrong with it. :-) What's it's useful load?
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Jul 14, 2014 06:40
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Yes. Many of the first and even second generation of ultralights only had (or have) elevator and rudder control. Anything controlled by weight shifting realistically only has two axis of control as well. Unless you mean "rudder and throttle" control, which is another story entirely. You're giving up a lot of control at that point. The ability to "get in to trouble" also means the "ability to get out of trouble" While I'll happily fly a free flight glider that has no control, I wouldn't ride a free flight glider with no control. Even powered parachutes have elevator control of a sort. By pulling on both control straps you can chose to slow down and descend more quickly.
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Dec 19, 2014 16:15
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edmund745 posted:So what control problems do powered parachutes have? quote:Because a powered parachute proves that you can have an aircraft that is entirely flyable yet never inverts, never stalls and never spins. Most important with powered parachutes, is that their speed range is very very small. You've got just a few miles per hour between the fastest you can go level, and the slowest you can go level. quote:Is fly-by-wire even a realistic option for homebuilt aircraft yet? What is the cheapest factory-built aircraft that has it?
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Dec 23, 2014 19:53
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edmund745 posted:Yea, and losing the parachute canopy and switching to a canard/fixed wing arrangement would totally fix that problem. This is what surprises me about the observation that such aircraft don't already exist. quote:That would not work for all purposes--but I would bet that for a lot of small aircraft/recreational flying a lot of people wouldn't have a problem with it. The people who flew single control airplanes the most, were RC people. They were able to weasel out a lot of control from a single surface, but those lessons don't translate well to flying a fully controlled airframe. quote:Well,,, I did not suggest the fly-by-wire option. As has been mentioned, stall speed is the single biggest factor in safety. This discussion starts to hinge on "who you plan to have flying." A 3 year old could fly a throttle + rudder plane. With no training. (also note I'm not talking canard, the "can't stall" stability can be built into other layouts as well) In that case, your crash speed, will be essentially your cruise speed. ... Unless you have an adjustable tailplane to act as speed trim. but at that point, you might as well give the pilot control of the elevator. This discussion has me thinking about flying cars. If you can treat a plane like a gokart, why shouldn't everyone fly? The factors that answer that, also indicate why a dumbed down airplane probally isn't ideal.
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Dec 26, 2014 04:56
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edmund745 posted:It's not my pet theory; powered parachutes have been flying around on single-axis control for ~33 years. PPG's are not as simple as you think they are. They have at least two, if not four controls. By pulling on the two drag lines at once, you can slow down the PPG, and convert some forward speed to lift. IIRC they also have "speed" lines too.. or that may just be paragliders. Those give you elements of control that a throttle and rudder airplane just won't have... unless it's very marginal. Using just rudder, people were able to climb, dive, and even loop single channel r/c airplanes. That said, nobody does that anymore, because more control is better. At some point here, you need to explain what you think the killer application of a two control airplane is. What would be the niche you'd sell into?
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Dec 27, 2014 03:27
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edmund745 posted:I asked about any examples of fixed-wing-single-axis control aircraft, and there appear to be none. At least, not known to anyone here. You keep saying it, but PPGs are NOT single axis control. The ONLY example of single axis control are r/c airplanes, they work. You've still not pointed out what the "killer app" for this would be.
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Jan 1, 2015 22:12
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edmund745 posted:Why do you insist they are not? I insist they're not, because the people who seriously use parachutes don't use single control canopies. You need to take a close look at why people fly PPGs. Because you're really missing why people fly PPGs. By giving up elevator control, you're giving up the ability to positively touch down, or take off. That's a huge risk factor. Stalls aren't scary. Uncoordinated turns is what happens in a "classically" designed airplane. You can make planes auto coordinate. Though that ends up only working right for certian airspeeds. You've still not convinced me that there's any significant group of people who'd want to fly a crippled airplane. You also seem to think PPG canopies are foolproof. A good gust at the wrong time will collapse the canopy and you're in deep doo-doo unless it decides it wants to re-inflate.
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Jan 4, 2015 02:11
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helno posted:Met some interesting people. Got to chat with Burt Rutan and a couple of his buddies while flying r/c aircraft. My jealousy is unending. I was up there on saturday, it was a good day.
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Aug 9, 2015 05:05
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helno posted:Parked. That doesn't ground you does it? Expensive, demoralizing, but does it stop you flying?
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Aug 10, 2015 04:15
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MrYenko posted:Finally, a fuel tank that makes your wedding tackle part of the crash structure! Never looked at a CriCri or Quickie eh? :-)
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Nov 7, 2016 20:57
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He... is better prepared than most people who've dove into that. His plane is already better than some plans you can pay for. He is a very, very, good TLAR engineer, and doesn't often get it very wrong. Each episode shows a lot of learning. While he didn't discuss it, between the night fligth, and yesterdays flight, he taped the wing gaps That alone took the plane from barely flying to solid flying. ... He has had lots of hours training for his PPL. He's got his ultralight, that's actually less than 254lbs. (which can't be said about a lot of them..) If he did math, he'd knock 10lbs off the plane... I wouldn't worry much. Peter is safe (mostly) and will provide entertainment for years to come. Just... dont' do what he's doing.
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Nov 1, 2017 08:55
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MrYenko posted:All the problems of multiple engines, with none of the power reserve! He's been out of ground effect. He was out of ground effect before fixing the leaking wing panels. The wing gaps are EXTREMELY important. For a long time GWS sold a plane called the slow stick. It had two wing panels attached at the center, with a gap between them. If you closed the gap, you got something like double the flight time, and a 50% better glide ratio. It's also worth mentioning, he's running on only 80% of the voltage his motors are designed for. So that's going to get "fixed" too.
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Nov 1, 2017 15:14
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helno posted:Even in the latest video it looks pretty marginal power wise. The places weight could be saved are numerous. He's still a totally legal ultralight. Wtih none of the "funny business" that many of the other ultralights do. LIke.. Belite and the removable fairings. Or the other electric ultralights having 5 gallons (volume) of battery...
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Nov 3, 2017 07:56
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