Supersonic alien bird.

FtlIsAwesome

I am working on a scifi series. This question crosses both Aerodynamics and Exobiology topics.

I thought it would be interesting to have a genus of nonsentient birdlike creatures on an alien planet and they can fly at supersonic speeds.
What would the physiology of these creatures be? They would probably need to be metallic, such as aluminum, stainless steel, or titanium.
I'm thinking that there are different species, some that fly at different ranges than others, and some different sizes than other species, and many variations in shape.
Humans refer to these group of creatures as "Concordeans".
They can alter the shape of their wings, and I'm guessing that they would require organic jet engines to travel at such speeds.

Here are some Wikipedia articles I skimmed over:
http://en.wikipedia.org/wiki/Concorde
http://en.wikipedia.org/wiki/Turbojet
http://en.wikipedia.org/wiki/Supercruise
http://en.wikipedia.org/wiki/Bird_flight

Like Earth birds, the Concordeans have hollow bones to reduce weight, possibly something lighter than what any Earth birds have.

These creatures would require enormous amounts of energy for supersonic flight. Some solutions for this:
Large stomach(s) to store food, but this would increase weight.
Use photosynthesis.
Eat other creatures in the air or on the surface of oceans, but the Concordean would probably need to slow down for this.
Eat microscopic "sky-plankton" during flight.
Large lung(s).

I want one species to be able to cruise at Mach 2-4 (2,500-5,000 km/hr; 1,540-3,080 mph) for a distance of 20,000-30,000 km (approximately 5 times farther than the Concorde), while another can reach higher speeds for brief periods, possibly even hypersonic (greater than Mach 5).

They would need some kind of cooling system to get rid of the heat from air friction.

JaredJames

Well their skin would need to be made of some fantastic substance. Supersonic aircraft can change shape when flying (see concorde for good references on this) due to the heat expansion. So you'd have to deal with that somehow. So far I don't believe we've been able to produce anything capable of surviving hypersonic speeds.

Also, how would they reach these speeds? Flapping just ain't gonna cut it.

FtlIsAwesome

How could they grow a metal exoskeleton, such as aluminum? One question will be as to how they get the refined metals.
On Wikipedia Concorde page, it says that aluminum would limit the speed to Mach 2.02 due to the high heat. Stronger metals/alloys, such as titanium, would be needed for higher speeds.

I quickly realized that such creatures would use jet engines (the Concorde used turbojets) rather than flapping. They could have different types of engines for different speeds/circumstances.

The pulse detonation engine, or PDE, is an experimental type of engine that could theoretically allow hypersonic flight around Mach 5.
"All regular jet engines and most rocket engines operate on the deflagration of fuel, that is, the rapid but subsonic combustion of fuel. The pulse detonation engine is a concept currently in active development to create a jet engine that operates on the supersonic detonation of fuel." - Wikipedia
I'm thinking that the specific species can only sustain such speed for a few seconds (or maybe one minute).
The ramjet, and especially the much faster scramjet, can reach hypersonic speeds but only work when the craft is in motion. I may use ramjets for the creatures, but probably not scramjets.

The biggest question is, if they have jet engines, where are they going to get jet fuel? The Concordeans will need some kind of fuel source that at least equates or surpasses our current fuel for aircraft.

Another nagging question is, why do they need to fly supersonic? This probably wrecks the whole idea. But if people have conjured up living starships, why not imagine some living supersonic aircraft?

Using the term "bird" isn't really correct, these creatures are very different from any bird we know. They more closely resemble a Concorde with organic insides.

They would present a major technological assistance to the sentient aliens on the planet once they learn how to tame the supersonic creatures. Later on the sentient aliens would try enhancing the Concordeans abilities (ie. adding more engines to them).

To further complicate it, the planet has a different atmosphere than Earth's. And I currently haven't figured out its properties, other than its unbreathable by humans and is green. The surface gravity of the planet will probably be different as well.
For now though, I will just focus on it as if the creatures were on Earth.

Now thinking about it, they may not be able to use photosynthesis because they need to be white-colored to reduce heat during flight.

JaredJames

Metal skeleton, look like concorde and jet engines? These aren't birds anymore, they're mechanical objects.

The engine capable of hypersonic flight - ramjet / scramjet - but we don't have materials that can withstand it.

Uhh, living starships are technically supersonic craft - they travel at hypersonic velocities all the time. The main difference is between doing it in space = possible and doing it in an atmosphere = currently impossible.

White coloured to reduce heat during flight? This is just plain non-sense. The heating during flight comes from extremely high air friction. Note, the SR-71 Blackbird is black and that goes faster than concorde.

Your whole concept has gone from a supersonic bird to a living Concorde.

Why would something like this evolve? What would be the purpose of it? Is it useful? (it's only useful if supersonic flight helps it escape predators - if there is nothing that can fly or there is nothing that can reach significant sub-sonic speeds then it is relatively pointless.)

FtlIsAwesome

I was referring to "anti-flash white". The Concorde used this to reduce heat stress.
Wikipedia:
"Concorde also had restrictions on livery; the majority of the surface had to be painted with a highly reflective white paint to avoid overheating the aluminium structure due to heating effects from supersonic flight at Mach 2. In 1996, however, Air France briefly painted F-BTSD in a predominantly blue livery (with the exception of the wings) as part of a promotional deal with Pepsi Cola. In this paint scheme, Air France were advised to remain at Mach 2 for no more than 20 minutes at a time, but there was no restriction at speeds under Mach 1.7."

"highly reflective white" redirects to "anti-flash white". Another use of this is on nuclear bombers.
But if they can be black, that's fine. I'm not really concerned about what color they are.

My concept hasn't changed, this was the idea from the beginning.

There will be other predators in the form of other supersonic species.

JaredJames

I can honestly say I've never heard of that. No amount of paint is going to reduce the heating from friction unless it makes the surface smoother. Not by being reflective.

If you read where it links to, it speaks specifically of thermal energy generated by a nuclear blast being reflected, nothing to do with friction heating.
But again, why would they evolve to such speeds and how?

That aside, you're not going to get an organic jet engine - particularly not supersonic ones. It has to be made out of metal.

As I keep telling people, in sci-fi, do what you like. Just don't try and explain it.

Personally, this idea is really pushing it even for sci-fi in my opinion. I struggle to accept Moya in Farscape when I'm watching that - which is what you are describing here.

What I believe you have here is a cross between Farscape and Transformers. I'll point out to you that transformers works for me because they don't explain anything.

RandomGuy88

The Blackbird was painted black to help keep it cool. Obviously the paint job didn't reduce the heat generated by friction but it allowed the surface to radiate the heat away better.

JaredJames

The blackbirds paint was designed to dissipate more heat than it generated at the supersonic speeds.

The problem I have is that although they specify the white paint for concorde (I don't doubt it had it), it says the paint is only effective at reflect heat - like from a nuke - so I don't see how it's of much use to concorde. Perhaps there's something missing.

FtlIsAwesome

Okay, I used the wrong term.

My brain can't process what you're saying. Things should always be explained and well defined if possible.
Unexplanation = bad
Explanation = good
Details + Explanation = good * 2

This is puzzling. It is illogical to say anything is impossible. Nothing is impossible.
And Moya is entirely believable. The only two things I didn't like is that they didn't state that StarBurst was FTL, and there was no secondary FTL to explain interstellar travel.

I can sort of see where you're getting Farscape from, but not Transfomers.

I fail to see how this is relevant.


This is turning into a one-on-one debate instead of a discussion with everyone. To prevent this thread from going off on a detour, I am putting you on my Ignore List.


Back to the original discussion, what would the various physical aspects of these supersonic creatures be?

JaredJames

Uh, no. Sci-fi is worse when they try and explain things. If you have an engine that can go faster than light, you leave it at that. If you try to explain how it does that, it is easy to see the flaws and why it won't actually work.

Things in the real world should always be as defined as possible, but so far as fiction (especially science fiction) goes, explaining everything is a bad idea - I can point you to a thread from not so long ago here where we discussed this exact thing relating to physics of movies.
Let's not go down this route. Things are impossible whether you want to accept it or not. For example, it is impossible to use a conventional rocket to accelerate to the speed of light.
Google Starscream - it's a transformer which becomes an F22 raptor (supersonic fighter) and acts exactly how I believe you want these birds to. In fact, I'd say he's perfect for you to look at.
Exactly. The evolution isn't relevant, because it's sci-fi. Yet a minute ago you are telling me how everything should be well defined and explained - if everything must be so, then you must explain how they got to be like that. You see, vague in sci-fi is good.
That is your choice, but no one here will tell you different and I will continue to respond - everyone else will see the responses. I'd also note that no one else has responded. Perhaps that tells you all you need to know...

RandomGuy88

Maybe instead of the bird propelling itself to supersonic speeds there are winds on this planet that reach supersonic speeds and the bird rides in these "jet streams" just like a surfer rides a wave. This would get rid of the propulsion problem as well as the friction heating problem.

Of course then you have the problem of how do you get supersonic winds, we can do it in a wind tunnel but that is because of the nozzle design. Perhaps the winds are at very high subsonic speeds so the bird rides the wind to Mach 0.9 or something and then is capable of providing the extra propulsion to get past Mach 1. But I suppose at that point you would only actually be traveling at Mach 0.1 relative to the air so you probably wouldn't technically be supersonic. I don't know though. Someone with more knowledge of compressible flow should be able to tell you what things would be like in that case.

Its your story so you can make up your own physics.

FtlIsAwesome

The properties of their planet will be useful in determining the aspects of the Concordeans, but I haven't nailed down all the attributes of the planet.

Definite properties
Name - Amasar
Approx average radius - 12,090 km
Surface gravity - ~1 g
Surface atmosphere pressure - no greater than 2 atm

Working properties
Average radius - 12,095 km
Equatorial radius - 12,122 km
Polar radius - 12,068 km
Oblateness - 0.0045
Surface gravity - 0.90 g
Surface atmosphere pressure - 1.5 atm

The problem with this planet is that it would get a thick atmosphere like Venus due to its high mass. This is a different topic, so I will start a thread for solutions to this and other details of the planet and its system, in either General Astronomy or Astrophysics.




Attempts at providing a "reason" for these creatures has generally resulted going around in circles.

So I will provide this answer:

With an infinite number of lifeforms across this universe, there will be lifeforms with abilities that have no apparent reason. Basically, pure randomness is what would charcterize an infinite variety of lifeforms.

JaredJames

That is not an answer based on any factual content.

There is no reason to believe there are infinite lifeforms and that is not how evolution works. Based on current knowledge, there is no reason to believe there will be lifefors "with abilities that have no apparent reason". This is purely speculative on your part and outside the rules of the forum.

You are making things up to suit your need - bad for reality - good for science fiction. You need to choose which you want. You either want reality or you want good sci-fi.

If you don't accept this, start a poll in GD about whether sci-fi is better when the author tries to explain the physics.

nismaratwork

A poll might be a good idea in general... if the idea of these "Concordeans" is going to destroy the carefully planned illusion that is fiction, it would probably be good to know.

mugaliens

Exactly. There are two genre's of sci-fi, one which does whatever it can to adhere to the laws of physics, and everything else all the way to the point of sheer fantasy.

Very few stories ever attempt to meet the demanding requirements of the former. Most combine elements of fact and science while extrapolating into the world of the believable, but not necessarily factual. The goal is to create a world into which the reader can immerse themselves without raising too many flags. That's often far easier to simply say "they engaged the hyper-drive" than delving into the physics behind it.

JaredJames

Thank you. I'm hoping the OP will take note of these posts.

I've noted a lot of people coming here for help with sci-fi and they seem to want far too much detail. Just reading the detail in the posts makes me not want to read/watch the end product - because I know at some point they're going to try and regurgitate it to me and let's face it, usually not as well as it should be, meaning you have actual science in sci-fi explained badly which just strikes another blow against it.