One variant of the tiltrotor concept is the “trailrotor.” The basic tiltrotor concept has the problem that the proprotors must be a compromise between efficient at low speed and efficient at high speed, and no such prop design exists. The trailrotor is a concept that focusses the proprotor towards low speed efficiency, and then slows, stops and folds the proprotor out of the way at high speed. High speed forward propulsion would be provided by a turbofan engine… which would be geared to run the proprotor at low speed. The idea has been an alluring one for nearly 50 years, but has one major flaw: extreme complexity.
The design below is an early 60’s Lockheed design, but the trailrotor concept has been studied by just about everybody, and certainly as recently as the late 1990’s.
5 Responses to “Trailrotor”
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It looks like something that would be a lot easier to fold up than deploy in flight.
I always thought the disk rotor idea was a lot simpler in concept, and you could probably use centrifugal force to deploy it and springs to retract it when the disk stopped spinning:
http://www.flightglobal.com/blogs/the-dewline/2007/10/boeings-next-big-vtol-surprise.html
That link, Pat, led to this: http://www.blueridgeairlines.com/
Some of the images are familiar from websites sent to me by the tinfoil-hat brigade.
I went back to look at the disk-rotor thing. Isn’t there something funny about disk airfoils? The center of lift moves forward or backward as speed increases, or something like that? There was an article in Air International, I think, a year or so ago about this.
Takes me to an article on flight global about the Boeing Disc Rotor design.
Update on it BTW; Boeing is currently building a 20% scale model of it for windtunnel testing by DARPA: http://tinyurl.com/27fr87n
That’s to the Aviation Week “Leading Edge” blog article on it.
(AW&ST really has to figure out that links with 326 characters in them are anything but user-friendly.)
I can tell you they suck as gliders; I tried that disc design, and it was a disaster area; the thing would either dive into the ground or go flipping end-over-end.
Maybe with fly-by-wire you could get it to work
can’t understand why the Boeing design has the big wings on it; the whole idea of the disc rotor is to use the disc as a wing surface when it’s not rotating.
With the Boeing design the rotor downwash will hit the top of the wing, pushing down on it and greatly decreasing the rotor’s lifting ability.
Maybe it’s just supposed to be a test vehicle for the disc rotor, and not some sort of a prototype design for a operational aircraft
Although its disc wing didn’t spin, seeing the video of the Triphibian’s failed flight from the National Mall in Washington is a riot:
http://www.youtube.com/watch?v=OFP8gLYu43A
They came up with a really impressive way of upping a small internal-combustion gasoline engine’s horsepower: screw supercharging, screw nitrous oxide injection, it runs on gasoline and LOX.
That’s why it goes up in such a fireball; the LOX feed line ruptured. 😀