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I'm pretty sure older Quicksilvers and many other ultralights have no ailerons, but they have elevators.
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# ? Dec 19, 2014 13:42 |
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# ? Mar 29, 2024 00:43 |
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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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Nerobro posted:... 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" There is a lot of info on "2-axis control aircraft" (mainly homebuilts) if one searches. None I found was using a canard configuration tho. Many that have 3-axis surfaces but 2-axis controls just link the rudder to the ailerons. Just about all of them that only really have 2-axis surfaces lack the ailerons and just have the rudder & elevator. Incorrect aileron use is the cause of spins but the elevator is how you stall, and the thought here was to avoid stalling or spinning. It's just idle chit-chat I suppose. The main cause of small aircraft crashes seems to be the engine suddenly not working at inopportune moments, and nobody has any good solution for that issue yet.
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# ? Dec 19, 2014 17:27 |
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edmund745 posted:
I could be wrong but I think the main cause of crashes is pilot error - controlled flight into terrain, loss of control follows I think, either vmc or imc. Full engine failure is pretty rare and generally usually happens just after maintenance. Once you get past the infant death period engines tend to go pretty well unless grossly mishandled.
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# ? Dec 19, 2014 18:16 |
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edmund745 posted:Yea that is what I mean. Which would be a "1-axis control aircraft", since they count control 'surfaces' and so they don't count the throttle.... Stalling while uncoordinated is the cause of spins. GA accidents are not mostly due to engine failure. Reducing control axes seems like a really misguided way to try to improve safety. Note that 2-axis ultralights have a very difficult time with even a light crosswind, for example.
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# ? Dec 19, 2014 18:28 |
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DNova posted:Stalling while uncoordinated is the cause of spins. quote:Reducing control axes seems like a really misguided way to try to improve safety. Note that 2-axis ultralights have a very difficult time with even a light crosswind, for example. Also years ago it seems like I read of a paraplane that had all three wheels as caster wheels. You could take off and land it running crazy-looking crab angles to the runway if you had to. It made sense to me (even for ultralights?) but none of the ones I'm seeing online now are like that.... Statistics are not hard to come by, but gathering any meaningful idea of them can be depending on how they have mixed different aircraft together. In this thread on the subject elsewhere, the "pro-3-axis-controls" people mostly just say that they're used to 3-axis and not having it would be odd or scary: http://www.homebuiltairplanes.com/forums/aircraft-design-aerodynamics-new-technology/11488-thoughts-simple-two-axis-control-aircraft.html To say that "a single-axis airplane doesn't have enough controls" doesn't really make sense tho,,,, because you are basically saying that there are airports that you can fly a normal plane like a Cessna 152 in and out of, that are impossible in a paraplane.
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# ? Dec 19, 2014 20:51 |
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As has been said there were definitely plenty of 2 axis ultralights. The Lazair started out life as one and was moved to three axis simply to make it easier to handle in a crosswind. The overhead stick models had options for a mixer that could be enabled and disabled for takeoff and landing but after the series 3 redesign that went away. In its original configuration it was much like a an ercoupe, limited elevator travel and mixed rudder and aileron meant no stalls and no cross controls. Unless you really mess with the CG and elevator travel the Lazair can never really stall enough of the wing to really call it stalled. I really like the idea of an electric PPG as it gets rid of much of the noise and starting problems inherent in small two strokes. And with a PPG you generally shut the engine down prior to touchdown so unless you are over an inhospitable area it is not really life threatening. There are other things that keep them from being idiot proof but like most things it is really knowing went to stay on the ground that determines that.
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# ? Dec 19, 2014 21:39 |
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helno posted:... As has been said there were definitely plenty of 2 axis ultralights. ... JUST rudder + throttle? .....or ailerons + throttle might work too I suppose.
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# ? Dec 21, 2014 23:49 |
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Well PPG are the only ones that fit into that and even then they can make pitch changes using the harness. Hang gliders can actually make changes on three axises using weight shift. Any craft that was controlled with only power and a directional control would be incredibly limited. Removing the ability to stall/spin just means you have to worry about other control problems and some of them are caused by the lack of control. I'm still not clear on why you want to get rid of 3 axis control. Any craft operating in the air will want to move on all three at some point or you might as well just drive a car. If you are worried about people mishandling things it is far easier to just use a fly by wire system than to try to solve that problem mechanically without giving something up.
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# ? Dec 22, 2014 00:12 |
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DNova posted:GA accidents are not mostly due to engine failure. Only 15% are caused by mechanical problems of all types including engine failure. Page 16 figure 8 http://www.aopa.org/-/media/Files/AOPA/Home/Pilot%20Resources/Safety%20&%20Proficiency/Accident%20Analysis/Nall%20Report/11nall.pdf
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# ? Dec 22, 2014 00:19 |
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helno posted:Removing the ability to stall/spin just means you have to worry about other control problems and some of them are caused by the lack of control. quote:I'm still not clear on why you want to get rid of 3 axis control. ... quote:If you are worried about people mishandling things it is far easier to just use a fly by wire system than to try to solve that problem mechanically without giving something up. (I know enough about electronics and programming to say that it can certainly be done DIY--but what is the legal climate like for such an aircraft? Is anybody actually flying anything like that?) I did find that same report and looked at it a while- http://www.aopa.org/-/media/Files/AOPA/Home/Pilot%20Resources/Safety%20&%20Proficiency/Accident%20Analysis/Nall%20Report/11nall.pdf But I noticed the chart Figure 50 at the bottom of page 43 (page 41 in the document page numbers). "Types of Fixed-Wing Amateur-Built Accidents" On the next page commenting on that chart, it says "Fifteen of the 24 accidents classified as “other or unknown” involved unexplained engine stoppages, a chronic problem area for amateur-built aircraft."
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# ? Dec 23, 2014 15:56 |
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edmund745 posted:So what control problems do powered parachutes have? I'm not very qualified to respond to this as I've no personal dealings with powered parachutes, but I was talking to a cameraman who did a bit of it on the side and had had two pretty major accidents. as I understood from one of them a bit of turbulence from a hill put him in an upset attitute leading to the wing partially collapsing and the cables getting somewhat tangled. wasn't able to get out of it before hitting the ground and it broke a lot of bones and an airlift rescue from a hillside as fortunately he was found by a walker. Powered parachutes also can't even remotely fly in the envelope that normal light aircraft can As has been mentioned previously if you can't fly out of balance your crosswind ability is extremely limited as well as the ablity to use useful techniques like side slipping to lose height / get down past obstacles.
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# ? Dec 23, 2014 16:47 |
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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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Nerobro posted:Wind gust caused collapse of the canopy is a big control problem. quote: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. You wouldn't be able to fly acrobatics with it, but it would be an enclosed cabin, much higher speed than a powered parachute, much less noise and much better fuel economy/longer range. 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. quote:... And what's the point? GA will always be positively or at least neutrally stable aircraft. Fly by wire doesn't really show it's advantages until an airplane is on the wrong side of the stability curve. But even so--how would a fly-by-wire system help anything at all? It would help by limiting what you could do with the controls of the plane. It would seem to be safer to design an aircraft to totally prevent unsafe maneuvers than to install a fly-by-wire system to prevent them, or to just use mechanical controls and hope the pilot never makes any such mistakes.
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# ? Dec 24, 2014 22:23 |
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So you want to get rid of spin/stall accidents but now have an aircraft that has a takeoff and landing speed that is the same as cruise. A big factor effecting aircraft crash survivability is the stall speed. Statistically the lower the stall speed the less likely you are to die in an accident because you generally hit the ground at close the the stall speed in most landings. This is what determines the 61 knot stall speed limit of single engine aircraft because anything above that is incredibly unsurvivable. What you are talking about throws that idea out the window. I can land and take off in a couple of hundred feet at around 25 mph and cruise around 40-50 mph. It I was limited to flying at my cruise speed I would need about 5 times the distance to get up to speed and my climb rate would be measured in the tens of feet per minute. I have control over all three axis of the aircraft but the elevator travel is limited so that it cannot stall and therefore cannot spin. PPG's are great at low speed but just because they cannot spin doesn't mean that they cant lose control in other spectacular ways (death spiral, canopy collapses. etc). PPG's are notoriously difficult to launch and the vast majority of the training is teaching you how to get the wing inflated and over top of you without collapsing. I witnessed a guy spiral one into the ground he was doing very tight turns close to the ground and got himself beyond the point of no return so when he tried to level out he hit the ground and broke his thigh. I really like the idea of PPG for low and slow recreational flying but it is because it is convenient not because it is any safer than fixed wing flying. Have you got any flight experience? It is actually quite difficult to spin most light aircraft and they require a huge amount of back force to stall. helno fucked around with this message at 00:22 on Dec 26, 2014 |
# ? Dec 26, 2014 00:16 |
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I'm still completely confused as to how you deal with a crosswind.
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# ? Dec 26, 2014 00:28 |
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PPG's deal with it by taking off directly into the wind but they take off at a jogging pace. The Ercoupe dealt with it by having beefy landing gear so it could land crabbed but I doubt you could beef it up enough to do the same thing at cruise speed. It is an interesting thought experiment but getting rid of the ability to spin/stall comes with plenty of other limitations.
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# ? Dec 26, 2014 00:51 |
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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: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. I can never tell when sarcasm happens, or maybe I've lost track of the thread, but isn't this what a weight-shift trike is? https://www.youtube.com/watch?v=d6hR-5i675U $17,990 no pilot's license req'd (in the US)
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# ? Dec 26, 2014 05:55 |
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Jonny Nox posted:I can never tell when sarcasm happens, or maybe I've lost track of the thread, but isn't this what a weight-shift trike is? I don't have any flight experience, so take it for what you will. But when you say "it won't work", you are ignoring the fact that it does work with RC planes, and with powered parachutes. There is a huge number of light/homebuilt accidents where the pilot adjusted the controls wrong for only a few seconds before realizing their error--and yet could not recover from the mistake. Every one of those pilots thought they were "smart enough to handle it". A LOT of these times, the pilot makes a high-banked turn close to the ground. Also a LOT of these times, the pilot is flying very close to the stall speed. https://www.faa.gov/aircraft/gen_av/light_sport/media/SportAccident.pdf 3-axis control on an aircraft makes perfect sense. It also leads straight into a LOT of crashes due to pilot error in operating those controls. An aircraft that had controls like a powered parachute would be a lot safer overall--because you would be forced to totally avoid the most unsafe types of maneuvers.
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# ? Dec 26, 2014 10:10 |
People have very patiently explained it multiple times but you've decided your pet theory is correct and are not open to any information otherwise.
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# ? Dec 26, 2014 11:03 |
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edmund745 posted:No, because a powered parachute has control surfaces--and a weight-shift trike has 2-axis + engine control, where a powered parachute only has 1 axis + throttle control. Go talk to a PPG pilot. They actually do much of the control with weight shift and the drag brakes are only used for large control inputs. I think you should go to a flight school and ask for an introductory lesson and ask them to demonstrate stalls and you will be able to understand why we think your idea is silly.
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# ? Dec 26, 2014 16:17 |
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edmund745 posted:huge number of light/homebuilt accidents... I would argue that there aren't really a huge number of accidents. As I said previously controlled flight into terrain accounts for a lot more accidents that the former or engine failure as you stated earlier. for a fixed speed aircraft, if people are wanting to cover a bit of distance really they're looking for about 90 knots minimum. that's a lot of energy to hit the ground with or runway to get up to speed to take off for a slow machine. let alone being unable to deal with a crosswind. Perhaps I'm thinking of the wrong type of aircraft, but lots of people fly 3 axis microlights and also possibly hire bigger 4 seater stuff to take more passengers / go places. One of the beauties of the microlights is that because they are cheaper to operate people can fly a lot more hours which keeps currency up which I would say gives one of the best safety advantages going.
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# ? Dec 26, 2014 20:02 |
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helno posted:Go talk to a PPG pilot. They actually do much of the control with weight shift and the drag brakes are only used for large control inputs. In the powered parachutes I was talking about, you can't do any weight shifting because you are firmly strapped into the seat. Ones such as these- http://www.sixchuter.com/ hailthefish posted:People have very patiently explained it multiple times but you've decided your pet theory is correct and are not open to any information otherwise.
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# ? Dec 26, 2014 20:53 |
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The Six chuter style is pretty unique. The vast majority of PPG is fans on backs style. You should ask Entone about those he bought one a few years ago and I havent seen any pictures of it other than the day he bought it. 25-28 mph on 40 hp is pretty silly when a more conventional PPG can take off into the wind at a walking pace on 10 hp. The Lazair does 50 mph on 18 hp. Unfortunately you seem to be missing the point we are trying to make. Not being able to control pitch means you are flying at a fixed speed and that means it has to be slow enough for take off and landing which is severely performance limiting. It is very easy to make an aircraft that is impossible to stall despite the pilots best efforts and most have very gentle stall characteristics to minimize the landing speeds which is the biggest factor in fatal accident rates. helno fucked around with this message at 00:22 on Dec 27, 2014 |
# ? Dec 27, 2014 00:03 |
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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. What is the point of all this? This is not a thread for kids with aspergers to tell us about their amazing new theories on a subject for which they have exactly zero training or foundation while summarily dismissing anyone with the same.
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# ? Dec 27, 2014 00:08 |
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even a J3 cruises at about 70mph on 40hp. It can also land in a crosswind. I keep looking at the thunder mustang every now and then. It seems like an incredible machine, but I imagine getting one into the UK would be nothing but hassle. Still 300 knots for 20gph is impressive. probably not really better than an rv to live with though.
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# ? Dec 27, 2014 02:54 |
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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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Colonel K posted:even a J3 cruises at about 70mph on 40hp. It can also land in a crosswind. You don't really live with a Thunder Mustang... you tend to die pretty quickly. There were (at least) three Thunder Mustang crashes in 2014 alone, one fatal, out of a fleet of only 37 aircraft.
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# ? Dec 29, 2014 07:23 |
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DNova posted:What is the point of all this? I find it odd that single-axis-control is entirely acceptable for powered parachutes, yet it is presumed to be wholly inadequate for fixed-wing aircraft. helno posted:The Six chuter style is pretty unique. The vast majority of PPG is fans on backs style. Sixchuter Powrachute Blackhawk Paramotor SummitPPC Infinity Powered Parachutes Skyview Powered Parachutes ...that's the manufacturers I saw in the first 3-4 Google pages, all of them only make trikes, and I think all these are in the US. edmund745 fucked around with this message at 15:01 on Jan 1, 2015 |
# ? Jan 1, 2015 14:52 |
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Jesus christ, quit while you are ahead. Or go loving build one and prove everyone wrong.
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# ? Jan 1, 2015 19:39 |
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edmund745 posted:Go to Google Images and do a search for "powered parachute". The trike-style is NOT unique. I was not denying the existence I was just explaining that they are much less common than the backpack style. Plenty of manufacturers make small trikes for people who cannot run fast enough to take off. Very few of them make large trikes like you are talking about. And again they are an example of a very inefficient vehicle. The Powerachute is a 100hp motor that goes 36 mph. Probably the closest thing to what you imagine is the Maverick flying car 190 hp 40 mph airspeed for the low low price of $94,000. http://mavericklsa.com/specifications.html It turns out that even it can have problems if it is loaded and/or rigged incorrectly so pilot error is still possible. https://www.youtube.com/watch?v=szvthEEZcp4 Here is a lesson on how and why paragliders and PPG fly the way they do. Parachutes are very different stability wise than fixed wing aircraft. They must be designed for a narrow speed envelope because they are inflated by the airflow. So the aircraft are designed to fly at that speed, if you add power they go up if your reduce power they go down. The harnesses are designed to keep the wing inflated and some actually have trim lines to allow a slightly higher cruising speed (this is effectively a very limited pitch control). There is such a thing as a high speed canopy and they are quite tricky to fly and kill a lot of people who botch the landings. TLDR: PPG's have limited control because they inherently cannot have full three axis control not because minimizing controls is a perceived advantage. Three axis flight control was literally the discovery that enabled the wright brothers to successfully achieve controlled powered heavier than air flight. Go take a discovery flight and a ground school course and you will realize why we think your idea is stupid.
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# ? Jan 1, 2015 21:50 |
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helno posted:Go take a discovery flight and a ground school course and you will realize why we think your idea is stupid. You're talking to a classical ideas guy. He's not going to do a goddamn thing about this other than make lots of nonsense posts and ignore anyone with criticism.
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# ? Jan 1, 2015 21:56 |
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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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Nerobro posted:You keep saying it, but PPGs are NOT single axis control. This page: http://buckeyedragonfly.com/ says in the FAQ: quote:6. Why a Powered Parachute? quote:You've still not pointed out what the "killer app" for this would be. Also it would be for people who don't ever want to stall or perform uncoordinated turns, since doing either of those things would not be possible (even intentionally).
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# ? Jan 3, 2015 15:06 |
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edmund745 posted:
http://www.ercoupe.org/
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# ? Jan 3, 2015 15:42 |
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edmund745 posted:
That would be because you are able to maintain different pitches at lots of different throttle settings in other aircraft. It doesn't directly control an axis only an amount of thrust. It seems like in your example you have absolutely no choice for a cruising for best speed or economy. or even trying to get to minimum flying speed to land. Your example is much more like a hot air balloon where the throttle is the axis control. I don't see how you can reconcile having a much higher cruise speed and what seems like no crosswind landing ability.
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# ? Jan 3, 2015 20:43 |
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Um,,, old? The newest ones would be 45 years old.... Also,,, they still stall, as this real-actual-video by an actual owner, flying who really knows how to fly----clearly shows: https://www.youtube.com/watch?v=y7IhGiyhI_w The stall might be mild by fixed-wing standards, but there is still some altitude lost and an amount of time where the controls were not effective. Powered parachutes don't ever stall or lose control effectiveness--as long as the canopies are inflated properly,,,, because they do not allow you to opearate the aircraft to the point that the controls would be not effective. Which goes back to what I said before--most of the shortcomings of powered parachutes for recreational flying (their cruising speeds, their fuel efficiency) are a result of the canopy, not the control system itself. Colonel K posted:... It seems like in your example you have absolutely no choice for a cruising for best speed or economy. or even trying to get to minimum flying speed to land. quote:I don't see how you can reconcile having a much higher cruise speed and what seems like no crosswind landing ability. So while they were still limited to flying in pretty light winds, the wind direction didn't matter much since you could do crab takeoffs and landings whenever you needed to. Now it appears that none of them I found are like that, and I don't know the reason for the change. ??? They still put one on the front? The wki article on crosswinds landings mentions the steerable gear of the B-52: http://en.wikipedia.org/wiki/Crosswind_landing And I recall a more-recent experimental jetliner that had the same thing. I wonder why all small aircraft don't have all-pivoting landing gear? It is difficult to build for a large plane (that would need power steering) but not for a small one that could just use caster wheels. It would seem to make crosswinds pretty much a non-issue.
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# ? Jan 4, 2015 01:23 |
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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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# ? Mar 29, 2024 00:43 |
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edmund745 posted:
quote:I mentioned before--some years back, maybe 20 years ago? a lot of the powered parachute trikes I saw in magazines came with caster wheels on all three wheels. If you're free castoring all your wheels how do you do ground handling and taxiing, or even braking for that matter without adding lots of complexity and weight? Crosswind gear was briefly available for some cessna models, I think 185s and 195s generally speaking though people didn't like it because it had unusual handling features, added weight, complexity and expense.
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# ? Jan 4, 2015 11:12 |