Dave Ansell

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Although for most airliners being able to change direction very quickly isn’t hugely important, as unmanned aerial vehicles are getting used more and more, especially in complex urban environments, being able to turn sharply can make the difference between carrying on its mission or ending up splattered against a wall.

A very productive seam of ideas for engineers has been bio-mimetics, copying ideas from living things. This has given us ideas ranging from velcro to catseyes in the road, but Brian Roberts and Rick Lind from the University of Florida and colleagues have been taking this strategy one step further. They have been taking ideas from dead creatures, very dead creatures that haven’t lived for 65 million years, pterosaurs to be precise.

These were a form of flying reptile which survived for over 150 million years and included the largest ever flying animal with a wing span of 40 feet. One striking feature of many of these pterosaurs is that they have large head crests. It has been suggested that these were just for display but they may have had an aerodynamic purpose, acting like a rudder.

So the group wondered if putting your rudder at the front of a plane might be useful. They have done lots of modeling and found that for the same size rudder at the front of the plane, it should give the plane a 15% smaller turning circle. The problem is that you also loose stability so they are looking into somehow morphing or moving the rudder around to get the best of both worlds.

So in the future we might see pterosaur inspired planes flying around our cities. Who knows what else ancient animals and plants might inspire.

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The next in military aviation :)

The pterosaur. yor_on, Wed, 22nd Jun 2011

It's all about the control system. If pterosaurs had the ability to control a forward rudder properly, it would have improved their maneuverability by trading off intrinsic stability. Geezer, Wed, 22nd Jun 2011

I think the all singing all dancing umpteen million pound modern fighter aircraft is one of the the most useless pieces of military equipment ever designed.
Spitfires and Messerschmidts were cheap enough to deploy in an actual war situation and had some effect on the outcome but modern planes are too expensive to risk and are about as useful as a F1 machine on the road. syhprum, Wed, 22nd Jun 2011

Quite so syhprum, and the often overlooked Hawker Hurricane shows just how cheap yet effectice a war plane can be.

So expensive are modern war planes that the military are turning to unmanned drones. With the cost of Typhoon Eurofighter at around £86m, it can be a great saving if you only pay around £10m for a drone, I think . But will all these advances in drone technology just lead us back to the same high costs for drones as for manned warplanes?

Perhaps if the fear of losing a well trained pilot were still present, we might be a little more reluctant to send in the bombers in the first place. Don_1, Wed, 22nd Jun 2011

I suppose it isn't quite the same, but canards have been incorporated in many different aircraft for years. 

http://en.wikipedia.org/wiki/Canard_(aeronautics)

If one was adding a forward tail, I would think that one might choose to do both a forward and a rearward tail, somewhat like having 4 wheel  turning on vehicles.

I agree is is a little silly to spend about $2 Billion per airplane (B-2) to invade a country like Afghanistan with a $25 Billion GNP.
CliffordK, Wed, 22nd Jun 2011

I can't help thinking that the answer to the question "Can Pterosaurs be used to model aircraft?"
is
"No, because they are all dead."
Being fossils and made of rock, they don't fly very well. Bored chemist, Wed, 22nd Jun 2011

Don't you believe that the "reconstructions" are 100% accurate? 

And that a species that obviously wasn't competitive enough to survive would be a better model than those that did actually survive.

Here is a Wikipedia image with quite a spectacular skull.
http://en.wikipedia.org/wiki/File:Pteranodon_sternbergi_pair.jpg



When a bird is attacking prey, it needs precise positioning of its head.  This may be different than an airplane that needs to position the entire aircraft.  Also, undoubtedly the entire neck would move in the direction of the turn which may prove to be different than having a fixed wing location on an aircraft.


CliffordK, Wed, 22nd Jun 2011

As I have explained before, I am no scientist, much less an aeronautics engineer. But I gave this question much consideration and then sat down and ritteded out (using two fingers) my thoughts. Java updated, kicked me out of everything and I cannot recover my post.

I'm not doing it all again!!!

So in brief, Pterosaurs were not capable of powered flight, they were gliders. Modern birds are capable of powered flight. To change direction quickly a bird needs to flap its wings to increase the airflow over the tail feathers. It can also alter its wing shape and attitude independently, thus giving varying power from each wing. The pterosaurs, on the other hand, had its greatest airflow at its head. Therefore, positioning of the rudder would be more effective on the head, rather than at the rear. So it seems to me that this might also be the case in a drone with its power source being at the rear, thus pushing the drone through the air, rather than pulling it.

The one thing I do wonder about, in this quest for tight turns, is just how tight can a turn be made at high speed? I would think a tight turn would be partly dependant on the speed of the aircraft. The faster it travels, the wider the turn. Don_1, Thu, 23rd Jun 2011

The reason for putting the tail at the rear of the aircraft (other than tails typically aren't at the front of anything).

Anyway, it gives stability to the craft. 

Consider what would happen if an airplane suddenly starts flying sideways in the wind.  If the tail is at the rear of the craft, then the cross-wind would push that part of the craft around behind and the craft would spin to the point where it is once again heading into the wind.

If the rudder was at the front of the craft, then the crosswind would be more likely to push that to the rear, and the plane would suddenly find itself flying backwards, which often is undesirable.

I wonder if you had a multi-engined aircraft, perhaps with rear mounted engines or exhaust ports (or perhaps wing mounted), and had a thrust imbalance (perhaps a dead engine).  Would a lack of a tail rudder cause the airplane to enter a spin?
CliffordK, Thu, 23rd Jun 2011

I can see it. Our Swedish prototype, hungrily turning its head looking for prey.
Take that StarTrek..

:)

With their trusty 'operators' hiding somewhere near, on this..
Hah.


yor_on, Thu, 23rd Jun 2011

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