The term “3-axis control” is generally held to mean active in-flight control in 3 axes - the ability to adjust your orientation by means of movable surfaces. Penaud’s flying toys, while intriguing (and influential), demonstrated passive, not active, stability.
O&W played with Penaud-style models when they were young. In his 1899 letter to the Smithsonian, Wilbur said:
“as a boy I constructed a number of bats of various sizes after the style of Cayley’s and Penaud’s machines.”
“Bat” refers either to a Planophore or a helicopter-style device (or perhaps to both).
Various biographies mention that in their teens they tried to build larger versions of these models, with limited success.
That certainly demonstrates controllability, that´s the point I was trying to make, that the priciples of flight control were well known by the time of the WBs, as I said they built a functional control system.
Originally posted by Ale
**Don´t want to sound repetitive, but seems that my first post went completely ignored, here´s the LINK again; the Wright brothers didn´t invent the 3-axis control system, they just built a functional one. Look at the picture of the Planophore, let´s review the stability issues
Horizontal stabilizator, check
Vertical stabilizator (rudder), check
Dihedral, check (it´s not very visible in the picture, however the original Planophore had elliptical dihedral)**
A vertical stabilizor is not a rudder. It is fixed like a boat’s center board and it adds stability. A rudder is what is attached to the stabilizor.
A nice site to look at. I never saw the later models he made, just the helicopters. You can certainly see the influence on future A/C designs. I’m surprised the Wright brothers didn’t build a stabilizer/rudder system like the Planohore.
Dihedral is not part of 3 axis control. It aids in flight stability, particularly in the ability to trim a plane for straight and level flight. (yes, a nit pic).
Stability and 3 axis control are not the same thing. a Stealth fighter has 3 axis control but is highly unstable.
3 axis control is the ability to maintain course and direction in 3 dimensions durring adverse wind conditions (such as crosswinds). It doesn’t have to be pretty HOW you got to the runway, just that you got there.
It may sound like splitting hairs, but what they claimed to have invented (and what they received their patent for) wasn’t wingwarping, but a 3-axis system of movable controls. Wingwarping was the method they used to differentially change the wings’ angles of attack in order to achieve roll control, but the patent didn’t depend on using that method. It thus withstood the claim that the use of ailerons was fundamentally different and thus not covered.
So it’s true that if you take a really narrow look at wingwarping, you can call it a dead end and insignificant. If you look at what the Wrights accomplished with it and the patent they were granted due to this, it becomes enormously significant – an integral part of how they achieved 3-axis control and manned flight.
Well I misspelled it too, getting tired of using spell check for my declining ability to type.
I honestly don’t see a toy (that doesn’t have control surfaces) as being a model of 3-axis control. It is a glorified lawn dart and that technology goes back a long ways. It IS a model of stability so I credit your original statement but that is not what the Wright Brothers invented. They invented 3-axis control. We are arguing apples and oranges (oranges rule).
I agree that this is an intriguing point. None of the literature I’ve read quotes either of the Wrights as particularly crediting their work with bicycles, but there is also no obvious and direct explanation for how they so quickly got on the right development path: figure out how to control it, get some experience flying it, and only then hang an engine on it.
That they got some of the necessary inspiration from bicycles (unstable, need some learning, but can be rather nimble) is very plausible.
As much as it could be descrived as a toy the fact remains that it flew on the same principles a full scale plane does; and the Planophore had control surfaces, the stab and rudder were adjustable, as well as the wing incidences which could act, roughly, as warping; granted it was a static 3-axis control, but the model could be trimmed to flight left, right, up and down. You can think of it as a test model, “let´s see how could I turn a big plane to the left”, add a bit of incidence to the right wing, and/or some left rudder, the model will tend to dive so a bit of up elevator should be set. I do thi all the time; free flight models have control surfaces (not all though), and those surfaces have to be adjusted to make the model fly in the desired path; I don´t see what´s different to a 3-axis control system then, barring the blindingly obvious that there´s no live input.
(…scratching head…) So… if it’s all about passengers… how do FedEx, DHL, Airborne, UPS, etc. manage to make enough money to stay in business?
LTA craft use less fuel per mile travel and a particular speed and weight. It’s because you only need enough thrust to propell the ship forward, you’re not burning fuel to keep you aloft. It’s possible that for freight this might make more sense than a high-speed aircraft. If we didn’t already have an extensive network of railroads filling that niche we might have blimps and zepps instead.
Also - cruise ships are terribly inefficient means of transporting people. But then, transport isn’t really the point, is it? Zepps could have a niche in the leisure travel industry (as a matter of fact, in their heyday they did occupy this niche).
Getting a zepp industry re-started would require an enormous initial outlay of capital with no guarantee of success - which has a lot to do with why we haven’t seen this. But the Graf Zepplin proved that LTA could carry both cargo and passengers, and did so from the tropics to the poles. It is certainly possible, but yes, I think that the HTA aircraft have in part bullied them out of the arena, and we haven’t had the incentive to make LTA truly economically feasible (for that matter, it’s questionable just much economic sense HTA travel makes).
Actually, by my standards anything built before 1910 (at earliest) was a pretty crappy airplane with a lot of inadequacies, regardless of control systems. That doesn’t mean weight-shift is an invalid means of controlling aircraft. As I pointed out, there are some designs flying today that are wholly weight shift, capable of carrying more than one person, and can go head-to-head with traditional fixed-wing three-axis aircraft in spot landings, manuverability, and cross-wind control. To say that weight-shift is impractical or useless or not important is much like denigrating rotorcraft because no helicoptor can carry 200+ people at 500 mph non-stop over an ocean.
We could have a perfectly viable air transport industry utilizing only fixed wing, 3-axis control, convential tail, tricycle gear aircraft with turbine, tractor configured engines. We don’t, in a sense. need canards, traildraggers, biplanes, pusher engines, rotorcraft, or piston engines for aircraft. But we do have them, and new ones are being built every year. Why? Because aviation isn’t just about passenger travel. As I’ve mentioned before, there are applications where rotors are superior to fixed wings, where pistons make more sense than jets, and even where canards are required instead of regular tails. It’s like arguing that because most twin engine aircraft these days have laterally mounted engines that’s a superior design - but it’s not inherently so. In-line thrust has some advantages, too, particularly in regards to controllability in the event one engine fails. Since the death rate from single-engine operations in multi-engine airplanes is significant, this is not an inconsequential matter.
I realize that to most people “aviation” means the airlines and the military, but it just ain’t so. I live in the world of small airplanes, and there’s more of them out there doing more things than most people realize.
If you want to fly low and slow on little fuel per unit of time/distance, a weight-shift aircraft makes a LOT more sense than a larger, heavier 3-axis fixed wing. Not only can these be mounted on skis or pontoons, just as conventional 3-axis, they also allow the operator to change the wing itself. A 3-axis fixed wing is just that - it’s a fixed wing, and what you have is what you will always have. A “trike” - a modern weight-shift - allows the wing to be swapped out so you can physically change the wing to better suit the mission at hand, and do so in a matter of a couple hours. The fact that the areas where such a system is superior is limited in no way detracts from their superiority in their own realm. Trikes do things 747’s can’t, and there’s enough need and desire for them that there is an industry to design, build, repair, and supply them.
Yes, certainly as a supplement. But I can conceive of a couple scenarios where, yes, you COULD lose all control over a control axis. Ice, for one - if that stuff gets into the control surface hinges (which it certainly can!) and freezes solid so does the steering. Control cables can break or slip off attachments (that actually did happen to me once - rudder cables slipped off the pilot side pedals. Fortunatley, the co-pilot side was still OK and there was someone sitting in that seat who could fly the plane. Although if I had been alone I certainly would have considered switching sides.) A bird strike could damage the plane in such a way controls are jammed. All sorts of possibilities that could leave your stick and rudder either much less effective or effectively useless. And don’t forget the Sioux City, Iowa crash - granted they didn’t weight-shift the DC-10, but they brought it in with NO 3-axis control, only differential steering. Not only is it possible to lose 3-axis control in an aircraft, it has happened more than once.
Weight-shift and differential thrust may not be our usual methods of controlling aircraft, but the concepts ARE important and worth knowing about.
Mmm… no, they’re designed to keep the weight where you put it. But there is considerable range of longitudinal axis effects based on where you put the seat position - which is why an elevator trim wheel is standard equipment. The “trim for take-off” mark on the wheel is a guess - fly a C150 for any length of time you’ll find a better spot for when you’re flying solo, and another based on the weight of a person sitting next to you. Sure, these are weight and balance issues, but the flip side is that if you had to do so, you could move that CG around a great deal by re-arranging the cockpit interior
I’m not convinced it was a good idea at all. Bluntly, I think it was a mistake, one they corrected in later models. We don’t engineer negative dihedral in ground effect or low flying vehicles today. We do, sometimes, add drooped wingtips to better manage wingtip vortices for superior low/slow/ground effect flight, but that is NOT the same as negative dihedral. Negative dihedral makes an aircraft less stable and less controllable.
Sure it will - certainly just as useful as, say, turning with just rudder when the ailerons aren’t working. The instance where weight-shift will probably work best in a small GA aircraft is in elevator failure (if the ailerons fail you use rudder). And there you do have a fair range in which to make adjustments, at least in some airplanes. A 150lb person (me) is heavy enough to weight shift a C150. That’s a bit light for a C172, but a 200+ person, or two smaller folks, could pull this off. Particularly in a Cessna high wing. Small, low-wing Pipers are more stable in many respects, which makes this considerably more difficult to pull off in, say, a Warrior. Of course, that’s just my experience in horsing around with these airplanes - I can’t speak for how effective this would really be in, say, a Cub or Taylorcraft or Luscombe.
(Use can also use the doors as steering mechanisms, too - there are all sorts of fun things you learn in flight training)
Now, in a Drifter or Quicksilver you can’t move the seats - they’re fixed - and you can’t get out of the seats because there’s no floor (it’s a looooooooong way down). But you don’t have to - the airframe is lighter, so just leaning will have more effect. Of course, those models are open cockpit - there’s a a drag effect from you sticking your limbs in the airstream you’d also have to account for. But you can weight-shift steer those, too.
Would I willingly start a flight in a 3-axis airplane and fly it weight-shift? Nope. But if I had to I think there’s a decent chance of it working. Hey, if things are THAT bad I don’t care if I trash the plane - I’m trying for ME to survive! That means do whatever you have to in order to impact the ground at a low enough speed that you live to tell about it.
Sam Stone—you have not figured military history an Cold War logic into your argument.
Zeppelins were vulnerable to Fighter in WW1. But blimps (a related airship) were used extensively by the US Navy in antisubmarine warfare patrol in WW2, because there were no Axis Fighters over the Atlantic.
After WW2, huge infrastructure for airplanes had been built the world over. Airfields, towers, hangers, et al.
Millions of men and women had learned to fly airplanes, navigate airplanes, repair & maintain airplanes.
Huge numbers of airplane factories had been built.
Existing military aircraft, especially transports and bombers, were converted to civilian use.
All of this precluded a re-assessment of airships.
The economic efficiency you claim to cite isn’t all it’s cracked up to be. Often, efficient solutions are ignored because existing infrastructes are expensive, and disposing of these older infrastructures requires a certain amount of vision & courageous leadership, which is usually lacking.
well, hmm… a philosophical gray area. Can an adjustable surface be considered a control surface? If you said yes then you have to consider an arrow as an example of stabilizing surfaces. Granted the goal is to make the arrow go straight, it is still a deliberate attempt to control direction and stability.
If you want to award bragging rights to model designs then you have to give the Britts credit for breaking the sound barrier. Their models worked but they canceled a full-scale airplane due to past fatalities. Chuck Yeager would kick your ass, but go ahead.
I know I slant toward the Wright Brothers because of hometown familiarity but I do enjoy reading about the accomplishments of all the other pioneers. The WB’s truly understood what they patented beyond they knowledge of everyone else and should be acknowledged for it.
A little trivia: the front elevators of the early WB machines were not parallelograms. They were deliberately articulated so that one elevator surface would stall at a different rate than the other. It effectively gave them a pre-stall warning.
Xema, I intended the reference to bicycling to help explain the Wrights’ piloting ability specifically, but you’re right in that it may also have helped them consider the control problem in fully 3 dimensions, not 2 and 1/2.
magiver, imagine a pilot in the Penaud machine wanting to climb or dive, or turn. How could he do it? The plane would stay going the same direction. That’s stability. The ability to change that direction in flight is controllability, and that was not present.
When carrying freight, compare ton-miles per day. (Surely you’re aware that an index of efficiency doesn’t become invalid because you offloaded the passengers in favor of freight??)
If we’re talking about what matters (fuel per passenger- or ton-mile), this is true at low speed, but wrong at high speed (something for which many customers will pay a premium).
Dubious - LTA craft are less efficient than HTA for time-sensitive cargos, and hopelessly behind railroads (and trucks and ships) for heavy hauling.
Howzat? They have lost the intercontinental routes due to the speed and cost advantages of HTA craft, but ships still haul millions (e.g. on ferries). I guess it’s possible to argue that cruise ships are marginally less efficient due to have been tarted up a bit.
Now yer talkin’. This is what LTA might work for, though it obviously depends on novelty, so the market may be limited. Here’s a link to the new Zeppelin company, which is trying to get going in the tourist ride business. Note that at 335 euros for a 1-hour flight, it ain’t cheap.
This has been alluded to previously. But what is the development that capital will finance and that will make LTA transport efficient and practical? If it’s a competitive idea, why won’t it work on a small scale first? Why do we need dozens or hundreds of airships before the first of them become practical?
In what way (other than demonstrating much greater efficiency)?
Several hundred million airline passengers a year might possibly quarrel with this. What’s a more economically sensible way to travel from, say, Chicago to London?
We might do well here to review and summarize up a bit. Weight shift came up because it was what Lilienthal used for control. My point was that this method of control did not contribute to the solution of the problem of manned flight, only became workable some 60 years later, and is employed for less than 1% of manned flight. This is not the same thing as saying that weight-shift control isn’t “valid” or can’t work, or doesn’t exist - I accept that it is, can and does.
I agree with much of what you say, though I’m skeptical that there’s any inherent advantage to weight-shift control when the goal is lightweight, low, slow, economical flight. And I know of several 3-axis control aircraft where wings (or parts thereof) can be swapped to suit conditions.
No doubt. And when it’s irretrievably lost, attempting control by weight shift is obviously better than doing nothing. But when your normal controls are working at all, they are almost invariably the best bet.
Worth knowing about - yes. But their importance is minor.
That’s what I was trying to say - sorry if I was unclear.
Consider that the Wrights were planning to use the Flyer at low altitude in a place with strong gusty winds. Dihedral does make a plane more susceptable to gusts (as their correspondence notes) so it would have been questionable on a plane to be used at Kill Devil Hills. And for dihedral to have its roll-stabilizing effect, the plane must sideslip a bit, which isn’t a great thing when flying at an altitude of a few feet. So it made sense to avoid this approach in 1903.
In 1904 they were flying at Huffman Prairie in Ohio. Winds were much lower there, and they eventually flew much higher. Accordingly, they took out the negative dihedral. They were smart guys.
Using the pitch effects of power is also valuable in this (mercifully) very rare event.
A sound plan. OTOH, keeping the plane intact will tend to ensure that you stay that way.
I think I may have sinned of unclarity here; what I´m trying to refute is the notion that the Wright brothers invented 3-axis control, the principles and method to achive that were well known (at least among the people into flight study) well before the WB designed the Flyer, Penaud was the first to understand how the tail surfaces worked and developed the first explanation of how to use it for stability and steering.
To me, saying that the WB invented the 3-axis control for airplanes is like saying that Edison invented light; no, he just invented a way to produce light, just as the WB came to a mechanical solution to provide 3-axis control. Well, actually 2 and 1/2 since the rudder was coupled with the wing warping for coordinated turning.
No it didn’t. If Zeppelins were really useful and airports were in their way, they could simply land wherever they want.
Your idea that there was no ‘vision’ or ‘leadership’ in the aviation industry seems to suggest that the decision to keep open airports was made by some central body. This is not the case.
If Zeppelins were more efficient at hauling general cargo, Fed Ex would buy them. If there was a side benefit of giving them the ability to moor closer to destination customers than an airport would allow, so much the better. They’d lease some property on the outskirts of the city and set up their own landing zone.
If they truly made extra profit from that, they would begin to under-price their competitors, and the competitors would also have to move to airships to stay profitable.
If enough did that, and enough passengers desided to go that way, then the old airports would become underused, and eventually would fade away.
But none of that happened, because airships were seen as more expensive, slower, harder to manage, or more dangerous than an equivalent traditional cargo plane.
