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bulldogtrekker
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Joined: 14 Dec 2013
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 Posted: Tue Feb 17, 2015 9:58 pm Post subject: |
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Well, I am glad everyone enjoyed the posts about the Roadair. The extra photos and the cutaway drawing were helpful.
There is no independent documentation that the gizmo ever flew. |
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Bud Brewster
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| Posted: Tue Feb 17, 2015 10:38 pm Post subject: |
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Ah-ha! Thanks.
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Last edited by Bud Brewster on Sun Mar 18, 2018 4:34 pm; edited 1 time in total |
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Robert (Butch) Day
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| Posted: Wed Feb 18, 2015 12:40 am Post subject: |
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"It is my understanding it briefly got about 6 inches off the ground, but no further testing followed. I acquired it as part of my Tallmantz Collection purchase in 1985."
Info from: http://www.fantasyofflight.com/aircraft/korean-war-post-wwii/1959-trautmann-roadair/
Still not documented proof of flight. BUT if the patent was properly issued then there had to be some proof for the US Patent Office.
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orzel-w
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| Posted: Wed Feb 18, 2015 4:44 am Post subject: |
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Sounds like it might have been similar to the Wright brothers first hop, or the Spruce Goose.
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Brent Gair
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| Posted: Wed Feb 18, 2015 10:29 am Post subject: |
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I don't want to be to aviation-geeky but I don't get this...
That wing (which is obviously WAY too small) has no control surfaces of any kind. There are no ailerons or spoilers for roll control. I can almost forgive the absense of flaps for the sake of simplicity but these wings are just big fins. I don't understand the aerodynamics of how this thing would turn. Seems those short coupled rudders with no roll control on the wings would make for dangerous flat skidding turns with a giant radius...if it turned at all before entering a terminal death spiral. |
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Bud Brewster
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| Posted: Wed Feb 18, 2015 11:24 am Post subject: |
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Good points, Brent. It looks like the wing itself can rotate at the point where it's connected the fuselage, so perhaps the whole wing is one big aileron.
Would that work?
The wireframe diagram in Wayne's post only shows a hinge that allows the wing to swing out from it's recess in the fuselage, but the picture above shows the wing twisted a few degrees counterclockwise from horizontal.
Of course, we also see that the wingtip is damaged, so maybe the wing is twisted because it's not actually attached correctly to the fuselage -- just laid out in roughly the right place for the museum display.
Does anyone want me to draw some nice colored lines on the photo to show what I mean?
No?
Well, okay . . . 
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Is there no man on Earth who has the wisdom and innocence of a child?
~ The Space Children (1958)
Last edited by Bud Brewster on Sun Mar 18, 2018 4:36 pm; edited 1 time in total |
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Brent Gair
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| Posted: Wed Feb 18, 2015 12:57 pm Post subject: |
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| Bud Brewster wrote: | Good points, Brent. It looks like the wing itself can rotate at the point where it's connected the fuselage, so perhaps the whole wing is one big aileron.
Would that work? |
I don't know. I can think of that introducing a host of unnecessary complications. I don't want to pass myself off as an expert. I'm trying to think of any other airplane that rotated to entire wing for roll control and I'm coming up empty.
Some aircraft (most modern fighters) can rotate their tailplanes independently ("elevons"- combined elevators and ailerons) to aid in roll control. In the old days, some aircraft like the Wright Brothers planes used wing warping where there was no separate control surfaces but cable could warp the outer wing for roll control.
I just don't know what the plan was here and if rotating the whole wing would work. I can't rule it out...but I can't think of an example where that is used (excepting things like missiles where the fins aren't actually lifting surfaces). |
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orzel-w
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| Posted: Wed Feb 18, 2015 2:50 pm Post subject: |
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| All-Aero.com wrote: | | At about 90 mph the Road Air lifted off the ground to about 3 feet. As Herb soon began to loose control, he set the Road Air back on the runway averting disaster. He put it in storage, never to be flown again. |
http://www.all-aero.com/index.php/home2/11138-trautman-roadair
We may be discovering why it made only one short flight. This low front view shows there was very little dihedral in the low-mounted wings.
Compare this with some high-performance aircraft like the P-51. The dihedral is almost identical.
The dihedral (angle of the wings in the front view) depends on where on the fuselage the wings are mounted (low, mid, or high) and how much stability/maneuverability you want. A fighter like the P-51 needs to be highly maneuverable, so a minimum of dihedral is used with low-mounted wings. A civil aircraft like a Cessna 172 has essentially straight wings (almost no dihedral), but the wings are mounted high, so the weight of the fuselage "hangs" below the wings, making for a very stable aircraft. I've ridden in a 172 and was even allowed to take the controls for a bit (that's how stable they are─I have no flight training). Banked turns are very easy. You can accomplish them by either pushing on one rudder pedal OR by turning the steering yoke (wheel). Doing both is unnecessary. If you use the rudder pedals, the tail starts swinging to one side, then the plane starts banking in that direction by itself. If instead you turn the yoke, the plane first banks in that direction, then starts turning. More sophisticated control, combining banking, rudder, and elevators, is used if you want to make harder turns and/or maintain constant altitude through the turn.
A jet fighter like the F-104 has wings mounted mid-fuselage and negative dihedral (wings angled downward), so control is very touchy.
So, looking at the RoadAir's minimal dihedral and low wings with no ailerons, observers watching the test flight must have heard a muffled "Oops!" from the cockpit when it became airborne.
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Brent Gair
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| Posted: Wed Feb 18, 2015 3:43 pm Post subject: |
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I actually learned to fly before I had a driver's license. My first solo flight was in a Cessna 150 Aerobat C-FCBJ on August 18, 1976. And I scored a reasonable 88% on the written exam. But I only flew for a few years...it's a very expensive hobby for a poor boy.
There have been some aircraft that have (in the past) done away with rudder pedals. the Ercoupe being the one that comes to mind.
But the Ercoupe did not do away with any control surfaces. It simply coordinated them so that turning the wheel to move the ailerons would automatically engage the rudders to overcome adverse yaw. It still had rudders, and ailerons.
Some modern aircraft will use spoilers for roll control since, unlike ailerons, they not induce adverse yaw (the tendency for a plane to yaw opposite the direction of bank).
I have seen model airplanes operate without ailerons. It's not impossible... but uncoordinated turns can go bad in a hurry, so it seems odd on a passenger plane. |
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orzel-w
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| Posted: Wed Feb 18, 2015 9:03 pm Post subject: |
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The Ercoupe is a good example of a stable low-wing aircraft. Note how much dihedral is built into the wings.
Those wing tips are all they way up in line with the propeller hub. Looks like it would make for a nice cozy cradle.
I've never flown any R/C models, but what I have noticed is that many scale free-flight and some R/C model plans have more dihedral in the wings than the full size aircraft they're modeled after. This increases their self-correcting tendencies and makes them less squirrely to control.
So anyway, the point I was driving at with all this lecture about dihedral and stability is that the RoadAir appears to have very little inherent stability, due to the low wing position and minimal dihedral. That makes the absence of ailerons very troubling.
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WayneO
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orzel-w
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| Posted: Thu Feb 19, 2015 9:34 pm Post subject: |
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| Brent Gair wrote: | | That wing (which is obviously WAY too small)... |
Don't forget that the fuselage is intended to provide some of the lift, being an airfoil shape itself. (Still, it does make me wonder just what Trautman's job description was at Douglas Aircraft.)
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