Would a jet work under water?

Question

I am 15 and have wanted to be an aerospace engineer since I was 10. Over the years I have come up with lots of ideas for new aircrafts, the first one I came up with was a plane I called the sea snake. It would start under water like a sub then using jet boosters under the wings it would shoot out the water.

It would use large hydrogine fuel cell, or some other way of seperating the H2O, for under water (it would use the hydrogine for fuel and send the oxygin to the pilot) it would use jets similer to the ones on jet skis but larger.

It would use scram or ram jet engines for flying threw the air due to the fact salt water destroy a jet engine with moving parts.

the shape would be like a f-14 tomcat when the wings are folded back

http://www.allwoodwings.com/1-MilitaryPlanes/IMAGES-MilitaryPlanes/F-14,SwingWing,VFA-142,swept.jpg

I know it prob won't work but I just want some ones opinon.

Answer 1

If you separate the water into oxygen and hydrogen...then since you are under water you need an oxygen source to burn the fuel. so it would work but the technology isn't available otherwise we would have hydrogen cars that you just fill up with water. I am studying to be a mechanical engineer. so good luck

Answer 2

submit ur idea

Answer 3

You really need to work on your grammar and spelling.  You will not be able to get into any decent college or university without passing basic English 101.

A little basic chemistry would allow you to see a few of your errors.

Where are you going to get the energy to run the fuel cell?  

The two HYDROGEN atoms will require one oxygen atom to recombine into water, none left to send to the pilot.

To answer your original question, where would the oxidizer for the fuel come from?  I do not think that your idea would work.

EDIT:  The KEYWORD is energy to separate water into two (2) Hydrogen atoms and a single oxygen atom.  Sorry for the typo in the first listing.

When the fuel burns, it will require one atom of oxygen for every two atoms of hydrogen, a net gain of zero atoms of oxygen.

You have several other issues that you need to address, but since you seem to have it sold, why bother?

I wish you well in your pursuits at community college.

Answer 4

I am having a very hard time understanding what you are trying to say...You need to learn grammar and how to actually type your words out before you even think about being an aeronautical engineer.  Why would the plane have to operate underwater to begin with??  Would it not then be a submarine?

I have to disagree with a previous poster that weight would not be an issue.  It wouldn't be an issue underwater until the plane surfaced.  

Why not try working on spacecraft?  After all, that's where the future is headed

Answer 5

hello apart other things, like lack of useful water molecule splitter iinto hydrogen and oxygen,

the turbines and compressors are made for a completely different fluid. thus a common jet engine would not work well.

the first thing is that water unlike air is not compressible - you dont need a compressor, what would actually be stuck all the time with the water supply. second the blades of the turbine are again designed for EXPANDING of hot gasses, which produces the torque for turboprop engines or simply torque for the compressor.

i furthermore suggest study on cavitation principle, which breaches the limits of speed of submerged moving objects.

typical cavitation vehicle is a Skhval torpedo, which produces something like a air capsule in the water. this enables the torpedo to float much faster than regular ones, since it

actually flies in the air rather swims in the water.

the cavitaion would work against you with your turbine, because it would produce bubbles following the blades of turbine, which would stuck the turbine flow and decrease its performance.

if you need to launch your craft submerged, either use solid rocket proppelants, or a airthight capsule similar to rocket launchers of submarines.

Answer 6

perhaps a shape like an F/B-22 will be better? it has delta wings so would work pretty good, or if not, something like the wings of an ME-109 would also work, but with elongated flaps.

The dynamics of moving through air and moving through water are pretty similar, and as such the mathematics of that are also pretty much the same. Only thing would be greater drag, so the shape would have to be streamlined, as well as crash avoidance (fish...poor....poor...fish....who wants fish sticks?).

Answer 7

There would be a major problem with the rusting of the engine being under water (salt water) Also there is a problem with harnessing enough energy from the hydrogen almost impossible to run a jet engine to go fast enough to propel at high speeds, last the problem with the oxygen ratio when burning fuel.

Answer 8

I know this is hard to take at your age, but you need to care more about your grammar right now.  I can see that you have some bright ideas, and I would encourage you to pursue a technical education.

But you need to understand that you live in a system in which you are required to lay down your demonstrated competence in layers like the courses in a stone wall.  To make the wall strong and stable, you must start with a level foundation and build the wall straight up, so that each layer of blocks rests directly on top of the previous layer.

The foundation for all achievement is basic learning, and that starts with clear communication.  To be able to express yourself clearly, you must have a correct understanding of the English language and be able to wield that language as a tool that will allow you to impress people with your ideas and apply force to human situations.

It doesn't matter how good your idea is.  If you misspell the name of a major component, the people who have the power to help you make your idea a reality will not take you seriously.  They will say something like, "This guy does not pay attention to details--he's a Geek, not an engineer."

So that's why you should care about your spelling and grammar:  you really can't get started without the basic reading, writing, mathematics, social studies, and general science that will form the first layers of your wall of blocks.  Get those things square and level, and the wall can go very high.

Having said all that, I would suggest that you sit down with a dictionary and an encyclopedia, and make a study of the word "Jet."  Find out what the difference is between a jet ski and a jet airplane.  That will get you started on an understanding of what parts of your idea are practical, and what parts will not work.

Write up everything you do, and take the time to get the spelling, word use, and grammar correct.  It will pay off for you Big Time, in the long run.

Good luck!

Answer 9

yes your right it wont work.

firstly, it would need too be much simpler in shape than a tomcat. theres no way you would get enough energy to push something like that throught the water.

secondy, heres the key rule in science and propulsion.

YOU DONT GET SOMETHING FOR NOTHING

why do you think jets use aviation fuel? because it is the smallst, lightest way of getting the huge amout of power neccesary to power a jet.

burning hydrogen and oxygen together creates water and  harvestable energy that han be used in a combustion engine.

that is where you intend on getting your power from yes?

well that wont work because you need to seperate water into hydrogen and oxytgen first which will use at least the same amount of engey to do. minis efficiency! and even if you used stored energy on board, the energy required to push the plane through the water is too much. the only upside is that weight is less of an issue.

there are plenty of other reasons why it wont work which i cant be bothered going into in detail (such as why would someone want this plane? millitary or personal? its too expensive for personal, and you may as well use special missiles in the millitary )  

plus no ones going to give you the funding for designing it - not even as a concept vehicle!

thats just my opinon, i hope it answered your question.

have a nice day!

Answer 10

It won't work.

The amount of energy needed to separate water into hydrogen and oxygen is equal to the amount that you would get from burning the hydrogen.

Water has two hydrogen atoms and one oxygen.  Anytime you burn hydrogen in the presence of oxygen (which is about the only way you can) you will need to have twice the amount of hydrogen as oxygen, and you will end up with water and no surplus oxygen.

Fuel cells turn hydrogen and oxygen into energy and water, not the other way around.

Though hydrogen would work for fuel on a jet engine

I'm a mechanical engineer, have worked for an aerospace company for over ten years, and worked on a hydrogen pulse jet (similar engine to V2 rockets) when I was in college