Burt Rutan’s Boomerang – Safety Through Asymmetry(wired.com)
wired.com
Burt Rutan’s Boomerang – Safety Through Asymmetry
http://www.wired.com/autopia/2011/07/burt-rutans-boomerang-safety-through-asymmetry
9 comments
Reminds me of the beautiful control theory concept of relaxed stability (http://en.wikipedia.org/wiki/Relaxed_stability). You intentionally craft instability in the system and use a controller to manipulate and exploit it, seemingly gaining extra performance for little cost. Unfortunately this doesn't even begin to scratch the surface of control theory but it's a neat introduction to an interesting branch of mathematics/engineering most CS people aren't aware of.
I believe that's how modern fighter jets are designed, for exmaple JAS 39 Gripen http://en.wikipedia.org/wiki/JAS_39_Gripen
They deliberately make them unstable and can then utilize that to make turns that are sharper than otherwise possible. The drawback is that they have to be controlled by computers all the time. This led to a spectacular crash in Stockholm in 1993 where luckily nobody was hurt.
They deliberately make them unstable and can then utilize that to make turns that are sharper than otherwise possible. The drawback is that they have to be controlled by computers all the time. This led to a spectacular crash in Stockholm in 1993 where luckily nobody was hurt.
The goal isn't actually to make the turns sharper. But to make the rolls quicker.
If you can change between maneuvers faster than your adversary you can cause him to be confused, giving you the advantage. This all comes from energy maneuverability theory which is the theory that modern fighters are based on.
Build planes capable of fast transients and a natural buttonhook tendency.
If you can change between maneuvers faster than your adversary you can cause him to be confused, giving you the advantage. This all comes from energy maneuverability theory which is the theory that modern fighters are based on.
Build planes capable of fast transients and a natural buttonhook tendency.
Yes, every modern fighter jet is engineered to be aerodynamically unstable and requiring intensive computer control just to be able to fly. It's part of the special sauce that lets them perform so deliriously ridiculously, and part of why the F-35 is the last human-piloted fighter jet. It's been beyond ludicrous for a long time now to maintain the assumption that a human pilot should be physically inside that thing.
I've been a fan of Burt Rutan since the VariEze first appeared on the cover of Popular Science in 1974. Oh how I wanted to build one of those planes. Burt Rutan has made more contributions to aerospace than anyone since Glenn Curtiss.
This wikipedia article is certainly relevant http://en.wikipedia.org/wiki/Critical_engine but I'm still not sure how the Boomerang can be so stable that it requires no rudder input during takeoff.
My guess is that by having one engine further back he creates the equivalent of the dihedral effect. If the plane starts to yaw in one direction. I have nothing but intuition to support this idea :)
I would love to see a detailed explanation of how this plane is so stable.
This wikipedia article is certainly relevant http://en.wikipedia.org/wiki/Critical_engine but I'm still not sure how the Boomerang can be so stable that it requires no rudder input during takeoff.
My guess is that by having one engine further back he creates the equivalent of the dihedral effect. If the plane starts to yaw in one direction. I have nothing but intuition to support this idea :)
I would love to see a detailed explanation of how this plane is so stable.
Another beautiful piece of non-obvious design.
I instinctively look for symmetry in my designs (and my purchases too I suspect).
I wonder if the reason it never 'took off' commercially was that people instinctively disliked the lack of symmetry?
I instinctively look for symmetry in my designs (and my purchases too I suspect).
I wonder if the reason it never 'took off' commercially was that people instinctively disliked the lack of symmetry?
It seems like it didn't take off commercially because it was just never pursued:
> Like many of Rutan’s creative designs, the Boomerang never went
> into production. There was never even a second example built.[deleted]
his another asymmetric http://stargazer2006.online.fr/aircraft/ares.htm
> Clements says the rudder pedals are rarely touched during flight, something unheard of for most pilots, especially those who fly small twin engine airplanes.
Is this really that unusual? In the Bulldog (which is very small and single-engined) you can get away with not using the rudder at all during normal flight.
Edit: Asked a friend who knows these things, it's not that unusual for a twin engine to not need a lot of rudder, but also not a rule either.
Is this really that unusual? In the Bulldog (which is very small and single-engined) you can get away with not using the rudder at all during normal flight.
Edit: Asked a friend who knows these things, it's not that unusual for a twin engine to not need a lot of rudder, but also not a rule either.
Best quote from this story, and how is it interpreted by different software makers: "You’re just going to screw something up. Best thing is to take your feet off the pedals and let it fly."
I can't get over how fascinating this thing is. Makes the "gristleships" in Alastair Reynolds's "Pushing Ice" all the more believable.
i think this must be more stable largely because the two engines are closer together (effectively one "side boom" is moved to the centre).
couldn't you do even better with a push-me pull-me configuration? then power would always be aligned correctly, whatever failed. perhaps that is less efficient, since the pusher is in the wake of the puller? it wouldn't look so fugly...
couldn't you do even better with a push-me pull-me configuration? then power would always be aligned correctly, whatever failed. perhaps that is less efficient, since the pusher is in the wake of the puller? it wouldn't look so fugly...
I'm pretty sure there's more to it than just that. For example, the difference in power output between the two engines wouldn't be necessary if the enhanced stability were due only to reduced distance between engines.
For example, the Blohm and Voss BV141, an experimental German aircraft, used an asymmetric single engine design wherein the weight asymmetry was balanced by the prop torque, which tends to cause yaw and generally needs to be trimmed out on non-counter-rotating twins and single engine airplanes. [0]
With regard to push-pull config: the Cessna Skymaster was designed this way. There are about 3000 of them flying around, including about 500 in military service, according to Wikipedia [1].
Another amazing aircraft design that never caught on and had some of the enhanced stability properties inherent in closer engine placement was the Beechcraft Starship [2]. For my money, it's the most beautiful business aircraft ever built, and it's got some seriously amazing aerodynamic features. For example, since it uses a canard design, it's very hard to stall: the canards will stall before the wings, which drops the nose, decreasing AoA and increasing lift.
There's an amazing image of a Starship chasing a SpaceShipOne during a test flight on the Wikipedia page.
[0] http://en.wikipedia.org/wiki/Blohm_%26_Voss_BV_141
[1] http://en.wikipedia.org/wiki/Cessna_Skymaster
[2] http://en.wikipedia.org/wiki/Beechcraft_Starship
For example, the Blohm and Voss BV141, an experimental German aircraft, used an asymmetric single engine design wherein the weight asymmetry was balanced by the prop torque, which tends to cause yaw and generally needs to be trimmed out on non-counter-rotating twins and single engine airplanes. [0]
With regard to push-pull config: the Cessna Skymaster was designed this way. There are about 3000 of them flying around, including about 500 in military service, according to Wikipedia [1].
Another amazing aircraft design that never caught on and had some of the enhanced stability properties inherent in closer engine placement was the Beechcraft Starship [2]. For my money, it's the most beautiful business aircraft ever built, and it's got some seriously amazing aerodynamic features. For example, since it uses a canard design, it's very hard to stall: the canards will stall before the wings, which drops the nose, decreasing AoA and increasing lift.
There's an amazing image of a Starship chasing a SpaceShipOne during a test flight on the Wikipedia page.
[0] http://en.wikipedia.org/wiki/Blohm_%26_Voss_BV_141
[1] http://en.wikipedia.org/wiki/Cessna_Skymaster
[2] http://en.wikipedia.org/wiki/Beechcraft_Starship
One of the Starships was based at our local airport for a few years. Very impressive looking aircraft. As I recall, it was a strange sounding beast; much noisier than you'd expect. Haven't seen it around in quite some time, though.
See also the Piaggio Avanti. http://www.piaggioaero.com/ One use to land at the airport near me (I have not seen it in a while). It also had a very distinctive sound (and was quite noisy).
I first found out about the Piaggio Avanti when I downloaded X-Plane 9 for the iPhone. The whole body creates lift and as a result it handles very differently from other small aircraft.
you know, there is a difference between "largely" and "only".
Yup, he built that too:
http://en.wikipedia.org/wiki/Rutan_Defiant
This is the kind of mechanical device where I could support patents, especially for a ~5-10 year span.