A question about giant pterosaurs taking off.

[checjb]

Have a read of Mark P. Witton's excellent book "Pterosaurs". It go into great detail of all aspects of these amazing creatures and covers flight, takeoff and how efficient their quarrelsome quadrapedal "walking" was. Oh, and he's a paleaontologist so actually knows.

 

[Minusorange]

They used pickup trucks to get enough speed to create the required lift

 

[Marky]

For the purposes of this question, assume that the pterosaur is not on a treadmill

Ah man, this changes everything!

 

[vanpeebles]

Does this help?

 

[Angilion]

I would also factor in that they may have had better lift with the skin rather than feathers. Also, reptiles are able to make huge bursts in acceleration due to how their muscles work, I know dinosaurs were not strictly reptiles but they could have had a similar bio function that was enough to launch the thing off the ground.

Pterosaurs weren't dinosaurs, but the general idea may apply. I wasn't questioning whether they could jump off the ground. Their chests, shoulders and arms were very muscular. My question was about how high they could jump and the details of the flapping needed to transition from jumping to flying.

I thought they used both their arms and feet to generate the initial lift, a super jump.

Yes, but mostly arms and chest. Those have to be far stronger to allow for flying, so being able to use them for other things is an advantage. But I was wondering how it was enough.

I heard the same theory, they based in on watching vultures and the like as I recall. don't remember the specifics but i'd guess if they lifted their wings and flapped down hard, given the size of the wing and the lift it would generate they'd gain height fairly fast. also, being as a wing is flexible and not like an aircraft wing, i'd thing it contacting the ground wouldn't be an issue - in fact, maybe it you actually give a bit of a shove upwards?

Maybe, but I'm thinking that an animal heavily adapted to flight with bones in its wings wouldn't be inclined to push its outstretched wings against the ground with any degree of force. It's the "flapped down hard" part that I'm questioning - did they have enough space to do that? How much of a flap would be needed to get enough lift to gain height above the launch jump? As you say, the size of the wing would mean that a flap would generate a lot of lift. How much flap would be enough?

probably ran and flap like swan.

honestly expected you to have watched a video claiming they still may exist

I think there wouldn't be any doubt about it if they did! People would notice. There would be threads in the motors section about them pooping on cars Also, air traffic control and air forces should notice a flying thing with a wingspan of 10 metres that hadn't filed a flight plan and wasn't responding to radio.

Was this the video? [..]

No, but that's a good one for my question. It shows a very small degree of flapping, with the wings barely moving below the body. Ground clearance wouldn't be a problem then. It also shows that they would have been jumping forwards a fair bit too, even without a runup. Seeing the proportional length of the wings helps me realise how much lift they'd get even from less movement in flapping. That motion looks right.

I think they'd have preferred to be heading downhill for takeoff, though. Big flying animals today minimise flapping where possible because of the energy requirements and the same must have been true in the past. No sense increasing your food requirements if you don't have to.

 

[v0n]

Lower gravity. Not just flying animals were bigger. Everything was. Trees, bugs, herbivores. Lower gravity, possibly planet revolved slower too.

 

[wordy]

I was watching a video about something (I forget what) and it mentioned that the common idea of these animals jumping off cliffs to get airborne is wrong and it's now known that these animals took off from level ground by jumping to get airborne and timing their first flap to gain lift at roughly the top of their take-off jump. I hadn't thought about flying animals taking off, so I watched some slo-mo footage of some modern birds taking off and that's how they do it.

But giant pterosaurs had a wingspan of over 10 metres. That makes me wonder how they got enough clearance for that first flap. Surely they couldn't jump 5 metres high. They weighed ~200Kg! Would a partial flap be enough to gain a little more height?

For the purposes of this question, assume that the pterosaur is not on a treadmill

Conclusive proof the dinosaurs never existed and the (flat) earth is only 4,000 years old.

Checkmate eggheads!

 

[arknor]

, air traffic control and air forces should notice a flying thing with a wingspan of 10 metres that hadn't filed a flight plan and wasn't responding to radio.

dont air traffic control use transponders ? and if they had a radar it would only be around airports anyway.
very little of the sky is likely monitored but if any did exist even just a few in the world someone would have taken a selfie with one by now

people still believe in the mothman

 

[tom_nieto]

For the purposes of this question, assume that the pterosaur is not on a treadmill

How can we possibly take this thread seriously?

 

[Unseul]

Lower gravity. Not just flying animals were bigger. Everything was. Trees, bugs, herbivores. Lower gravity, possibly planet revolved slower too.

Lower gravity? Where's that from??

Biggest animal to ever live, lives today (that we know of).

 

[Rroff]

Lower gravity. Not just flying animals were bigger. Everything was. Trees, bugs, herbivores. Lower gravity, possibly planet revolved slower too.

That was one of the first things I looked up but in the age these creatures were around the evidence tends to suggest there was less than single digit difference in gravity compared to today. You have to go back quite a long time before that for significant differences.

 

[NVP]

I'm not 100% on my recolection about the pterosaurs, but I think it was similar to fellow theropod, the pistorius, and had Össur blades allowing for much more spring in their initial launch.

 

[v0n]

Lower gravity? Where's that from??

Biggest animal to ever live, lives today (that we know of).

That's not quite correct in terms of sheer length, but - that's not the point - think land living animals. Argentinosaurus, Patagotitan, Paralititan, Puertasaurus, Alamosaurus. 50-80 tons of body with a heart muscle pumping blood to the head stretched 20-25 meters up and chewing on a 50 meter high Paraphyllanthoxylon and surrounded by dragonflies with 75cm wingspan* (* - not necessarily within the same era, ⟨± 180,000,000 current earthly years of "poetic license" taken⟩) . But yeah - the true logical answer for a standard size of flora and fauna across 500 million years - gravity on earth was simply lower.

That was one of the first things I looked up but in the age these creatures were around the evidence tends to suggest there was less than single digit difference in gravity compared to today. You have to go back quite a long time before that for significant differences.

They're wrong I'm afraid . Different gravity, definitely different axis (and axial procession). Possibly slower rotation, slower procession around the sun and ever so slightly closer orbit. Once you think it through, it's all occam's razor.

 

[Unseul]

That's not quite correct in terms of sheer length, but - that's not the point - think land living animals. Argentinosaurus, Patagotitan, Paralititan, Puertasaurus, Alamosaurus. 50-80 tons of body with a heart muscle pumping blood to the head stretched 20-25 meters up and chewing on a 50 meter high Paraphyllanthoxylon and surrounded by dragonflies with 75cm wingspan* (* - not necessarily within the same era, ⟨± 180,000,000 current earthly years of "poetic license" taken⟩) . But yeah - the true logical answer for a standard size of flora and fauna across 500 million years - gravity on earth was simply lower.



They're wrong I'm afraid . Different gravity, definitely different axis (and axial procession). Possibly slower rotation, slower procession around the sun and ever so slightly closer orbit. Once you think it through, it's all occam's razor.

Got any evidence to back it up?

A nice post on it: https://galileospendulum.org/2013/02/25/was-weaker-gravity-responsible-for-large-dinosaur-size/

There may have been minor differences sure, but the sort of difference required to explain that?

Big insects was due to the much higher oxygen percentage. As you've pointed out, the timeframe between them and the dinos is significant.

 

[v0n]

Got any evidence to back it up?

A nice post on it: https://galileospendulum.org/2013/02/25/was-weaker-gravity-responsible-for-large-dinosaur-size/

There may have been minor differences sure, but the sort of difference required to explain that?

Of course I don't (have an evidence). Dr. Francis can be militantly aggressive and dismissive all he wants, but the simple truth is - the idea that animals of a size of a Cesna and a muscle structure on those dug up bones powerful enough to stretch 13 meter wings, produce 2.5G uplift in a single flap and launch 250kg body into the air at sharp angle create way more physical problems than a simple and elegant solution that the earth inhabited by those animals was simply not the earth as we know it now.

I'm not even sure if we need any additional "proof" other than otherwise inexplicable gigantism of nearly all flora and fauna on earth confidently inhabiting the planet for hundreds of millions of years with very few size related mutations, compared to the current official version.

Dr. Francis elects to believe that all those animals lived in 1g and moved around like in Godzilla movies or dragons from GoT, and it's his right, he holds a title in his field and you and I don't.

But since I don't have a lifelong volume of bovine excrement on the subject to defend - instead of applauding men believing in dragons I elect to follow hard physics. The notion that the earth of dinos worked differently before getting hit hard with a fast earth bound bullet from space and ending hundreds of millions of years of gigantism once and for all - doesn't upset me, doesn't make any difference to me, but - you have to admit - it explains almost absolutely everything you can think of so far whereas such super giants flying, running, chasing prey, wagging 30 meter tails and mulching through tons of fuel a day required to maintain muscle mass to keep those sizes in motion in 1G, relatively unchanged, for so long... is... well... at least somewhat lacking?

 

[Minusorange]

it explains almost absolutely everything you can think of

So does saying prehistoric leprechauns sprinkled magic space dust on all the dino's that caused them to grow so large, doesn't make it true or based on anything scientific

 

[silversurfer]

Might not be a cliff but some prehistoric windy weather, cant be just the animals that were savage.

claiming they still may exist

only place I expect they might find that is an area isolated in some way. An extended cave system, polar subterranean waters or the japanese trench, volcanic outlets perhaps but all those areas would involve the smallest of creatures. The aboriginal people had an eagle so large it could lift a person but it went extinct as the easy prey was wiped out, it first thought to be a myth but actually proven correct now amazingly

 

[Rroff]

They're wrong I'm afraid . Different gravity, definitely different axis (and axial procession). Possibly slower rotation, slower procession around the sun and ever so slightly closer orbit. Once you think it through, it's all occam's razor.

Gravity is almost entirely related to the mass of the Earth. Centrifugal and related forces are a tiny point of a percentage in effect here - you would need a dramatic difference in rotation speed to have any effect here. If I remember correctly you would actually need an increase in rotation speed to aid flight as that would result in a body being pushed more away from the Earth - though I might be wrong on that as it is a long time since I studied those subjects.

 

[Angilion]

Lower gravity. Not just flying animals were bigger. Everything was. Trees, bugs, herbivores. Lower gravity, possibly planet revolved slower too.

Eh, what? Lower gravity? How? Gravity is a function of mass, so you're arguing that Earth gained a lot of mass between then and now. How? Planet revolving slower? What do you think caused it to speed up since then?

The giant bug time was many millions of years earlier, by the way.

Also, the rotation speed of the Earth has gone down over time, not up. If the solar system lasts long enough, Earth would eventually become tidally locked to the sun. But that's nothing for us to worry about as the sun will cook or melt the Earth long before then.

 

[Angilion]

[..] The aboriginal people had an eagle so large it could lift a person but it went extinct as the easy prey was wiped out, it first thought to be a myth but actually proven correct now amazingly

Haast Eagle. Less than 1000 years ago IIRC. I doubt if they could have lifted a person, though. Killed and eaten a person, yes. Lifted one, no. Maybe a child.