Size of Dragon Hydrogen Bladders

[Admiral Valdemar]

Y'know, if you're going to be true scientists, use SI units. I'm fed up of Imperial crap showing up when everyone does calculations on this board in metric.

It could be that methane was used instead (it's certainly biologically produced) for producing a flamethrower effect, or possibly some kind of binary chemical like in the film Reign Of Fire which at least gets around the problems of having a flammable liquid in your body.

But this really is speculation without any real idea of what these critters would be like, assuming they're your typical dragon shape (old English given those wacky Chinese ones have no gorram wings!).

[Lord Zentei]

Y'know, if you're going to be true scientists, use SI units. I'm fed up of Imperial crap showing up when everyone does calculations on this board in metric.

It could be that methane was used instead (it's certainly biologically produced) for producing a flamethrower effect, or possibly some kind of binary chemical like in the film Reign Of Fire which at least gets around the problems of having a flammable liquid in your body.

But this really is speculation without any real idea of what these critters would be like, assuming they're your typical dragon shape (old English given those wacky Chinese ones have no gorram wings!).

The lift of H2 is 1.1 kg per cubic meter at sea level, and no other gas exists that has better lift as far as I'm aware. An animal that has a bladder 10 meters in length and one meter in diameter will therefore have a lift of 34.5 kg. It isn't worth it.

[Sporkzen]

For some reason this thread has made me envision large flying explosive fire breathing blowfish...

[The Third Man]

Y'know, if you're going to be true scientists, use SI units. I'm fed up of Imperial crap showing up when everyone does calculations on this board in metric.

It could be that methane was used instead (it's certainly biologically produced) for producing a flamethrower effect, or possibly some kind of binary chemical like in the film Reign Of Fire which at least gets around the problems of having a flammable liquid in your body.

But this really is speculation without any real idea of what these critters would be like, assuming they're your typical dragon shape (old English given those wacky Chinese ones have no gorram wings!).

The lift of H2 is 1.1 kg per cubic meter at sea level, and no other gas exists that has better lift as far as I'm aware. An animal that has a bladder 10 meters in length and one meter in diameter will therefore have a lift of 34.5 kg. It isn't worth it.

You're overstating by a factor of 4 - radius, not diameter So it's just a poxy 8.5kg. It seems to me unlikley that you could make a viable 10x1m structure out of organic stuff (bones, gristle, skin, what-have-you) that is sturdy enough for the job at such a low weight.

We could look at bigger structures (say, 10m diameter spheres) to see if we gain anything by scaling up, but then you run into the problem of weight of supporting ancillaries - the heart(s) which pumps blood through the skin of this enormous sack for example, which start adding to the total weight again.

Maybe it might work if the creature made its hydrogen envelope out of something light-weight and low-maintenance (in terms of blood requirement etc) like, say, spider-silk, but then the creature would finish up looking nothing like a dragon as we know it. It would certainly not be able to behave anything like a mythical dragon either, being such a fragile, lightweight and flammable beastie.

[Lord Zentei]

You're overstating by a factor of 4 - radius, not diameter

I blame the lack of edits, my recent 36 hour work stint and an invisible dog chewing up my keyboard for this elementary error.

We could look at bigger structures (say, 10m diameter spheres) to see if we gain anything by scaling up, but then you run into the problem of weight of supporting ancillaries - the heart(s) which pumps blood through the skin of this enormous sack for example, which start adding to the total weight again.

Maybe it might work if the creature made its hydrogen envelope out of something light-weight and low-maintenance (in terms of blood requirement etc) like, say, spider-silk, but then the creature would finish up looking nothing like a dragon as we know it. It would certainly not be able to behave anything like a mythical dragon either, being such a fragile, lightweight and flammable beastie.

All in all, super strength muscles and a conservative size would be a safer bet.

[wolveraptor]

Fish might be a round-about start. They separate the O from H2O with their gills. You just need a way to collect the hydrogen.

Wrong.
They only collect the O2 that's in solution in the water; they don't break up the water itself.

that'd be pretty cool if they did break up the water molecule. each breath would result in nuclear fission. boom boom.

[wolveraptor]

Did no one see my post? we already have the wing length and size on our hands. We don't have the volume of hydrogen on our hands though. Just remember that there is a good deal of it in the bones, which are hollowed.

[xcr]

I would think that it would make most sence for a Dragon to depend on its wings in order to fly, and to be built in a mannor befitting such an animal. On that note, how large are the largest flying animals know to have existed- anyone know?

[AMX]

that'd be pretty cool if they did break up the water molecule. each breath would result in nuclear fission. boom boom.

Also wrong.
Breaking up a molecule is a chemical process, not nuclear.

[Darth Raptor]

Seriously, are you expecting to find a bio-chemical means of producing enough hydrogen to not only lift a large animal but the H2 production units as well? Forget it. You would be better off with boi-fusion or something.

The dragons' means of hydrogen production is identical to methane production in extant species, only dragons posess a unique strain of digestive bacteria that gives off hydrogen instead of methane. For an ignition catalyst, they chewed platinum. A false palate in the back of the skull (similar to what keeps crocodiles from drowning) kept the dragons from exploding while they used the flamethrower.

[Lord Zentei]

The dragons' means of hydrogen production is identical to methane production in extant species, only dragons posess a unique strain of digestive bacteria that gives off hydrogen instead of methane. For an ignition catalyst, they chewed platinum. A false palate in the back of the skull (similar to what keeps crocodiles from drowning) kept the dragons from exploding while they used the flamethrower.

I seem to recall a different mechanism from the Flight of Dragons cartoon. Not that it matters: I reiterate my earlier point that biological production of H2 will not be sufficient to lift the entire animal. The fact that it is a symbiote that takes care of the H2 production matters not one whit.

[Darth Raptor]

I seem to recall a different mechanism from the Flight of Dragons cartoon. Not that it matters: I reiterate my earlier point that biological production of H2 will not be sufficient to lift the entire animal. The fact that it is a symbiote that takes care of the H2 production matters not one whit.

The hydrogen is not lifting the animal; the wings are. The hydrogen in the flight bladders and that infused within the skeleton merely contribute to a light-weight build that makes it possible to fly. It's not a zepplin, it's a one ton bird made hollow with air-sacs filled with lighter-than-air air. Expending hydrogen reserves doesn't drop it out of the sky, the added weight makes it too tiring to fly and forces the animal to land.

[The Third Man]

It's not a zepplin, it's a one ton bird made hollow with air-sacs filled with lighter-than-air air.

Hmm. But the figures say that for a one tonne creature, if we want to ease the load on its poor tired muscles by just 1% we will need a hydrogen sac more than 10m long and 1m diameter.

That's just to improve it's fly-ability by 1% and it's a pretty blimp-like spec; for anything better than 1% the thing will definitely resemble a zeppelin.

[Broomstick]

I would think that it would make most sence for a Dragon to depend on its wings in order to fly, and to be built in a mannor befitting such an animal. On that note, how large are the largest flying animals know to have existed- anyone know?

Quetzlcoatalus, as referenced on page one. Pterasaur. Wingspan between 35 and 50 feet (somewhat speculative, given that I don't think a complete skeleton has been found).

[Broomstick]

And yes, I know I'm back to the damn Imperial units but I'm a bit mind-friend these past few days and can't find my handy converter. Call that about 12-16 meters in wingspan, close enough.

[Broomstick]

Y'know, if you're going to be true scientists, use SI units. I'm fed up of Imperial crap showing up when everyone does calculations on this board in metric.

1) It's pretty fucking ironic to here that from you seeing as YOUR COUNTRY came up with Imperial measures in the first place, then imposed them on most of the world for some considerable time.

2) I guess I'm not a "true scientist"

I have the useful information that the maximum wing loading of a goose is 2 lbs per square foot, or, as near as this native of a former British colony can figure on my fingers and toes, about 1 kg per .01 square meters... which seems ludicrously high to me, but if you don't like my math figure it out yourself. I hasten to add (if anyone is bothering to listen - the reading comprehension in this thread seems low anyhow) that geese, like most birds, already have hollow bones.

And if you could point me to some handy site that has a useful metric/imperial calculator maybe I'd more consistently post with metric, because frankly I don't care to spend three fucking hours performing calculations just to have the dubious privilege of joining a conversation involving idle speculation about creatures that doesn't even fucking exist.

Anyhow, at one tonne (metric spelling, note) the thing would have massive, massive wings - the square/cube law is going to catch up with you fast.

The heaviest flying critter currently living is the greast bustard, at 21 kg. Wingspan is about 2.5, maybe 3 meters long. Which doesn't tell us the wing area or wing loading. The albatross has up to a 4m wingspan, but again, without the area you can't determine wingloading.

Compare, again, to the extinct quetzlcoatlus at somewhere aroun 15 meters - which may have been a better glider than flyer. Well, that's the biggest, and presumably heaviest, flying critter the planet has yet produced. About the size of a small, four seat airplane - but much lighter and with much less horsepower.

As for lift gasses - you're pretty much stuck with hydrogen or helium... except that helium isn't something that living animals can generate through chemical means, or find in handy containers lying about. So it's hydrogen or nothing.

[Hardy]

1) It's pretty fucking ironic to here that from you seeing as YOUR COUNTRY came up with Imperial measures in the first place, then imposed them on most of the world for some considerable time.

Yes. And the British actually grew out of using such bizzare units. While ironic, it's still a pointless Ad Hominem.

The Imperial system is one of the few things that makes me most ashamed to be an American.

I have the useful information that the maximum wing loading of a goose is 2 lbs per square foot, or, as near as this native of a former British colony can figure on my fingers and toes, about 1 kg per .01 square meters... which seems ludicrously high to me, but if you don't like my math figure it out yourself.

95.76 Newtons per square meter.

And if you could point me to some handy site that has a useful metric/imperial calculator maybe I'd more consistently post with metric

http://www.google.com/help/calculator.html

And I apologize for nitpicking, but I am slightly angered.

[wolveraptor]

that'd be pretty cool if they did break up the water molecule. each breath would result in nuclear fission. boom boom.

Also wrong.
Breaking up a molecule is a chemical process, not nuclear.

of course

it's splitting the atom that creates nuclear fission.

[Elfdart]

The fact the wings did the flying and the bladder just lightened the load somewhat helps a bit; it mostly reduces the wingspan requirements into the realm of possibility.

But really, any discussion of calculations requires the dimensions of the critter.

I never understood why they didn't just give the dragons bigger wings. The best dragon on screen is still Vermithrax pejorative from Dragonslayer. She was about 40' long with a wingspan of 90' (or 13 and 29 metres for metric nerds) and looked like something that could fly. If they wanted something with shorter wings, why not give it flamingo-like length/ wingspan ratios? You'd end up with a more serpentlike dragon resembling those in classical art. Or a scaled-up Archaeopteryx or Ramphorynchus.

[Queeb Salaron]

that'd be pretty cool if they did break up the water molecule. each breath would result in nuclear fission. boom boom.

Also wrong.
Breaking up a molecule is a chemical process, not nuclear.

Yeah. We used to do that in 8th grade science class with a couple of electric diodes and some salt. And then we lit a match to the test tube with the O2 in it, and it went "Foop!"

Coolest noise ever.

[Mark S]

On the fire breath issue, I suppose there isn't much way an animal could produce a liquid that ignited when in contact with air?

Flying: Could it have a huge wing span and only glide? Or is a ton too large for this?

[Queeb Salaron]

On the fire breath issue, I suppose there isn't much way an animal could produce a liquid that ignited when in contact with air?

So that when it opened its mouth to eat, it burst into flames.

I'm sure Darwin would call that a disadvantageous adaptation.

[Broomstick]

1) It's pretty fucking ironic to here that from you seeing as YOUR COUNTRY came up with Imperial measures in the first place, then imposed them on most of the world for some considerable time.

Yes. And the British actually grew out of using such bizzare units.

Yes, that's why the English still express body weight in units called "stones".

The problem is that metric is a foreign language to me - I got almost all of my basic training in science back before Jimmy Carter's push to metric the US and prior to college metric wasn't hardly mentioned even in science classes. I learned physics mostly with Imperial units. Heck, when I was a kid even soda was still sold in pints, not liters, and illegal drugs were sold by the ounce and shipped by the pound, not by the gram and kilo. I even remember when Canada made the switch from Imperial to metric (they were still working on the adjustment back in the 1980's, which contributed significantly to the Gimli Glider incident). So when I "translate" there's always the possibility of my screwing up, just like those who don't speak English as a first language sometimes stumble over that. This transition has been made within the lifetimes of quite a number of people, and us old fogies are going to be at a disadvantage for the rest of our lives.

And if I recall, when the Concorde was built there was a to-do between the British and French over whether Imperial or metric units were used - the British haven't been as purely metric as they like to think, and certainly not for as long as they portray themselves to have been.

I have the useful information that the maximum wing loading of a goose is 2 lbs per square foot, or, as near as this native of a former British colony can figure on my fingers and toes, about 1 kg per .01 square meters... which seems ludicrously high to me, but if you don't like my math figure it out yourself.

95.76 Newtons per square meter.

I'd like to mention that, due to being tired last night, I misplaced a decimel point. It's about 1 kg per .1 square meters. Does that affect the newtons? I'm not even sure what newtons are a measure of - wing loading is normally expressed as a unit of weight (the load) and a unit of area (what supports the load).

I never understood why they didn't just give the dragons bigger wings. The best dragon on screen is still Vermithrax pejorative from Dragonslayer. She was about 40' long with a wingspan of 90' (or 13 and 29 metres for metric nerds) and looked like something that could fly.

That wingspan area probably isn't big enough, even so. In fact, it's probably a third of what a dragon would need. Keep reading.

Flying: Could it have a huge wing span and only glide? Or is a ton too large for this?

Nope, a ton is not too large for gliding. In fact, Boeing and Airbus sized planes have been successfully glided to a safe but completely unpowered landing. Air Canada (757) and Airtransat (Airbus) have both had such incidents occur. Gliding is not dependent on weight (or at least not that alone).

The airplanes I fly range from about 3/4 to 1 metric tonne (roughly). Including not only the wings but the tail and fuselage area you're looking at about 10 square meters of area that supports the weight in flight, with a 9 meter wingspan. The unpowered glide ratios range from 7:1 to 3:1 (the latter is a glide, but it feels/looks more like a controlled fall than what folks usually think of as a glide). A 7:1 glide ratio means that for every 7 units of length the aircraft moves forward, it descends 1 unit at best. Birds that do a lot of gliding, like gulls, have glide ratios closer to 20:1. Yes, I realize I'm mixing machines and animals here, bear with me.

So, clearly, a theorectical creature of 3/4-1 tonne in weight with a 9-10 meter wingspan and about 10 square meters or so of wing area could, in fact, glide without power although it would be far from a champion at the activity. And would be about the same weight as a small airplane, though the body, not requiring a passenger/cargo area, would probably be smaller than the fuselage of such an airplane.

Gliding, however, is not powered flight. Due to the limits of flesh and blood, 10 kg/sq m is about the maximum wingloading for sustained, powered flight in an animal. So, to support 1,000 kg in powered flight an animal would require about 100 sq m of wing area/supporting area. Configure that however you want, it works out to something the weight of a small plane requiring ten times the wing area of that airplane for powered flight. It's going to be big and fragile. Which doesn't totally eliminate the possibility - jellyfish are fragile predators that exist in vast numbers. But big and fragile isn't compatible with high winds.

For another interesting take on animal-powered flight, check out MacCready's Gossamer Condor and Gossamer Albatross - man and machine were somewhere in the 150-200 kg range in weight and capable of sustained flight (the Albatross successfully crossed the English Channel) using solely human muscle power. However, the damn thing kept breaking and could only be flown in relatively calm air, and the wingspans were enormous.

The lifting capability of hydrogen may help support such a creature, but the more it relies on lifting gas the bigger the volume and the more fragile the creature.

[CJvR]

The Dragon design can't work without either a lower gravity, a higher atmospheric density or some superlight & superstrong construction materials & muscles.

I think the Diskworld dragon answered the question best, it can only work as long as you run it on magic.

[Mark S]

On the fire breath issue, I suppose there isn't much way an animal could produce a liquid that ignited when in contact with air?

So that when it opened its mouth to eat, it burst into flames.

I'm sure Darwin would call that a disadvantageous adaptation.

I was thinking more along the lines of it being stored in a sealed vemon sack or created directly from something like a saliva gland under the tongue. The liquid would by no means always be present in the animal's mouth to explode whenever, just 'spat' or sprayed out when needed.