Physics Assignment

[PyroTek]

Not sure if this is the right forum, but it's the one i frequent most.
For my Physics Assignment, I have to do an EEI (Extended Experimental Investigation).
I'm pretty sure that you can do anything for it, for instance, my mate did a tesla coil 2 years ago, and another did experiments with audio waves.
I'm thinking I want to do something relating to aviation, such as finding the most efficient propellor, for example. (You don't have to make a new kind of thing, just be able to start from a basic stage and work up to a more advanced conclusion, as far as i know).

Now, I was wondering if you guys had any ideas of what I could focus my EEI on? Something to do with aviation of course.

Thanks heaps!

Pyro:D

[hogespa28]

Every flight I do is an 'Extended Experimental Investigation' :\

[PyroTek]

well I can't exactly take my physics teacher flying just yet.:ok:

[Lasiorhinus]

Sure you can - that would make it VERY experimental.

[forget]

Prove - once and for all - that spnining up wheels before landing has absolutely no benefit on tyre wear. Easy.

[PyroTek]

forget: Doesn't it?

[Lasiorhinus]

If you need to ask the question, why not make that your focus.

There are quite a few patents for tyre pre-spinners out there (look on google patents), so you should be able to get some ideas for mockups.

Run a few controlled experiments using rotating and not-rotating tyres, and see how much is worn off in each landing....

[Spinnerhead]

Or that other great PPL argument that is just dieing for a through physics investigation.

"Does your indicated airspeed decrease when you turn downwind?"

We all have our own beliefs - some very strong and wrong.

[Peter Fanelli]

Put a plane on a huge conveyor belt........

[Mach E Avelli]

What about the cargo of birds in a box? Hit the box with a stick to get the birds flying under their own steam - does the weight being experienced by the aircraft change?

[PyroTek]

is that even humane?!:uhoh:
And I strongly doubt it would, if the box is a closed environment, may be different if it is a cage, but if inside an aircraft, it'd still be a closed environment. Wouldn't lift the aircraft any... i dont think...

[OZBUSDRIVER]

Have fun with Coanda effect vehicles. End up looking like flying saucers that really do fly. Mostly unknown to the average punter so could earn points with the teacher.

Coanda demonstration (http://jlnlabs.online.fr/gfsuav/index.htm)

anyone that checked this before, :ooh:ummm this a more conventionally powered model

[Lasiorhinus]

The birds in the back of the truck is a classic example. Its usually phrased along the lines of a truck, weighing two tonnes, is carrying one tonne of live birds in the back, and arrives at a bridge with a maximum capacity of 2.5 tonnes. The driver bangs on the side of the truck with a stick while driving across, with the aim of keeping at least half of the birds flying at any given time.


Trouble is, its false. In a closed environment, the weight of the air being pushed downwards to counteract the weight of the bird exacts a force on the floor of the truck equal to the weight of the bird. (assuming the bird is not climbing or descending).

Actually, if your truck is tall enough, and you can get all the birds to the very top of the container right before you reach the bridge, and all the birds stop flapping their wings, and just glide slowly towards the floor, and you're quick enough crossing the bridge, you might make it in time... gliding (descending) birds do not exert a force on the floor of the truck.


Best way to test this - get a lot of birds, a truck, and go play on a weighbridge.

[sleemanj]

Actually, if your truck is tall enough, and you can get all the birds to the very top of the container right before you reach the bridge, and all the birds stop flapping their wings, and just glide slowly towards the floor, and you're quick enough crossing the bridge, you might make it in time... gliding (descending) birds do not exert a force on the floor of the truck.

You are joking right?

[forget]

This'll get better than the conveyor belt thread. :ok:

[Lasiorhinus]

You are joking right?

Am I? Do you have any proof either way? :E

[PyroTek]

Well, despite the birds, maybe i'll go for experimenting with the shape of a wing.

[Lasiorhinus]

How about the aerodynamic or otherwise properties of the bumblebee?

[Spikey21]

If a fly has parked his ass on your ceiling, when you scare him off does he drop, roll, and then fly away or does he fly off inverted and then roll upright ?????

:confused: :E

[flog]

Trouble is, its false. In a closed environment, the weight of the air being pushed downwards to counteract the weight of the bird exacts a force on the floor of the truck equal to the weight of the bird. (assuming the bird is not climbing or descending).

It so isn't a closed environment. :ugh:

Go and look up your fluid dynamics and the properties of air in a non sealed environment (which unless you got some fine and fancy truck for carrying birds in, sure is vented to the atmosphere.)

A bird near a truck - flying along above the truck bed (in or out of a box, assuming it's not sealed in - in which case refer Heir Schrodenger and a little QED) is not flying by forcing wind down onto the truck bed at an equal weight to the bird. Cmon people, we're pilots here, at least some of us should know how a birds wings generate lift...It's kinda similar to something else we know that has wings and can fly.

:mad:

[PyroTek]

tie birds to the bottom of the truck? that'd get it off.

[Hasselhof]

Back to reality... why don't you figure out an experiment based around a home built pulse-jet engine?

See here (http://www.youtube.com/watch?v=AePLpM5SnqE), here (http://www.youtube.com/watch?v=teQXaqeEnl8), here (http://www.youtube.com/watch?v=yZTAMPfJ2Us&feature=related) and here (http://www.youtube.com/watch?v=1Fr00GjghnU) for some demos.

Wikipedia (http://en.wikipedia.org/wiki/Pulse_jet_engine) page on pulsejets.

One of my mates made one out of a berrocca can and it worked great until his wife made him stop :{

Good luck :ok:

[Lasiorhinus]

Louie probably does a reverse of the flip technique he used to get himself inverted on the ceiling in the first place.
I'd imagine he lets go with his back and middle feet, while still hanging on with his front feet, for just long enough to swing around until he's facing the opposite direction, then lets go with the front feet, and flies away.

Here's a description (http://www.coolquiz.com/trivia/explain/docs/flies.asp)of how it gets onto the ceiling. Read it backwards to find out how it gets off again, later.

[flog]

You could try out the fabled Cat-Buttered-Toast Array.

Theory is that if you take a cat and strap buttered toast to it's back, butter side up, then drop it - it should spin, hovering above the floor without touching the ground.

Take a number of these and place them under a vehicle and you got yourself a hover car!
--
Everything works in theory...

[carbon]

Back to reality... why don't you figure out an experiment based around a home built pulse-jet engine?

That gets my vote, the ultimate fuel to noise conversion machine! Horrific BSFC, and pretty useless thrust wise, but wow what a noise!:ok:

[PyroTek]

could be a nice disruption to the class :ok:

[Mech-prentice]

Actually, if your truck is tall enough, and you can get all the birds to the very top of the container right before you reach the bridge, and all the birds stop flapping their wings, and just glide slowly towards the floor, and you're quick enough crossing the bridge, you might make it in time... gliding (descending) birds do not exert a force on the floor of the truck.

Well, no. Birds in free-fall won't, because they're accelerating freely. Birds gliding are just like people in a steadily descending lift (if they stand on scales the weight shown will be normal). The air is still bearing their weight.


It so isn't a closed environment.

Go and look up your fluid dynamics and the properties of air in a non sealed environment (which unless you got some fine and fancy truck for carrying birds in, sure is vented to the atmosphere.)

A bird near a truck - flying along above the truck bed (in or out of a box, assuming it's not sealed in - in which case refer Heir Schrodenger and a little QED) is not flying by forcing wind down onto the truck bed at an equal weight to the bird. Cmon people, we're pilots here, at least some of us should know how a birds wings generate lift...It's kinda similar to something else we know that has wings and can fly.

In my experience, someone being a pilot has been a poor indicator of them knowing how wings work. Many have fiercely defended the "two particles of air separated at the leading edge must meet again at the trailing edge" fiction to me.

A bird (or anything) flying generates downwash. If it's immediately above something like a truck bed - close enough that the downwash impinges on it - then the bed will turn (hence accelerate) that flow. That means the bed will feel a force exerted by the downwash.

If the truck container is built so that air can continually flow in the top and out the bottom then the flying birds won't add to the weight of the truck. If the air is recirculating within the container then the weighbridge will detect the full weight of the birds, flying or not. If only some portion of the air is recirculating and the rest is flowing through the container, then the weight of the container will change while the birds are flying, but not by the whole weight of the birds.


PyroTek:
The tyre wear idea seems like a pretty nifty project. One where it's feasible to fairly thoroughly experiment with most of the variables (pre-spun, not pre-spun, over pre-spun, landing speed, tyre material, runway material) and come out with a pretty compelling case one way or the other at the end.

For super-bonus points, do a cost/benefit analysis on tyre pre-spinning devices: if it saves you 75c per flight in tyre wear but costs $1.75 per flight in increased fuel burn for the added weight, then even though they'd work (hypothetically) they wouldn't be worth using.

[forget]

Birds gliding are just like people in a steadily descending lift (if they stand on scales the weight shown will be normal).

My brain's gone into a sort of seizure. Is that right :confused:

[PyroTek]

PyroTek:
The tyre wear idea seems like a pretty nifty project. One where it's feasible to fairly thoroughly experiment with most of the variables (pre-spun, not pre-spun, over pre-spun, landing speed, tyre material, runway material) and come out with a pretty compelling case one way or the other at the end.

For super-bonus points, do a cost/benefit analysis on tyre pre-spinning devices: if it saves you 75c per flight in tyre wear but costs $1.75 per flight in increased fuel burn for the added weight, then even though they'd work (hypothetically) they wouldn't be worth using.

I'm just not sure if I'll have the time or resources to perform an experiment that thorough...

[Lasiorhinus]

In my experience, someone being a pilot has been a poor indicator of them knowing how wings work. Many have fiercely defended the "two particles of air separated at the leading edge must meet again at the trailing edge" fiction to me.


Oh, if that's in any way unclear, have a look at this British Airways training video (http://www.youtube.com/watch?v=1SwECTyXaA4). The bit about lift generation starts at 3:30

[Capt Fathom]

Here's one close to home Pyro...

I need the formula for Bundy Rum.

Email me at [email protected] :E

[tooty]

Here's one on Bernoulli's prinnciple

Experimenting with Bernoulli's Principle (http://scifun.chem.wisc.edu/HomeExpts/bernoulli.htm)

The most interesting physics of flying is lift. Why not build a little wind tunnel with a fan or hair dryer. Then put something like smoke into it so you can see the streamlines. Then expereiment with a few different wings and AoA. you could verify some results and get an overall picture similiar to here

FoilSim II 1.5a beta (http://www.grc.nasa.gov/WWW/K-12/airplane/foil2.html)

[Lasiorhinus]

And see if the particles of air do meet up at the trailing edge, or not!:E

[PyroTek]

tooty, my school has it's own wind tunnel. all good :D

[Carambar]

Jeez, what school do you go to!

[Fark'n'ell]

Lasiohnus

Curious as to how flies s**t on the ceiling without making a mess over themselves.:ok:

[Lasiorhinus]

My school had a wind tunnel, too. It was where most of the lockers were, so on a winter's morning everyone froze while getting books for class.

Fark, I don't think the flies are that concerned where it lands. Perhaps they DO get it all over themselves.

Maybe Pyro could film flies to answer this question for us?

[PyroTek]

not saying which school, but it's a small wind tunnel, about 30x30cm in width/height. about 1.5 metres long, it's for the Design/Technology Department, But I'll give it a go.

[PyroTek]

Alright, sorry to double post, but I have come across an issue,
Is there a way to look at, say: the chord line, camber, etc to work out the Lift Coefficient?
Has anyone got any resources I could look at so I can calculate things from the shape of the wing?

thanks
Pyro:ok:

[ForkTailedDrKiller]

Yeah Pyro, I would start by calculating the Co-efficient of Gravitivity for a variety of different aerofoils, using the formula:

r=(15 + c − int(c / 4) − int((c − k) / 3) + 19 * (m mod 19)) mod 30

Where:

r = the co-efficient of gravitivity
c = the cord of the aerofoil
k = the maximum height of the aerofoil, and
m = the rate of change of k across c

You will then be able to demonstrate which aerofoils are able the overcome the force of gravity most efficiently for a given weight.

Should be a pinch of piss for a smart young fella like yourself!

Dr :8

[PyroTek]

by K, max height relative to what? the ground?

also,
Rate if change of K across C?
m= d/dx k/c? :confused:

and, by "int" do you mean 'integral sign'?:ugh:

[CaptainInsaneO]

Co-efficient of Gravity?

Correct me if I am wrong, but I thought the amount of Gravity an object has, is dependent on the amount of mass of that object.

Therefore the amount of Gravity (with reference to earth) would be fairly constant. Being approx 9.8m/s^2

We measure Gravity in terms of acceleration, which has units (in SI) metres per second per second. The fact that there are units means that it is not a co-efficient.

Are you meaning to refer to the Reynolds number, or the co-efficient of friction? Or Am I completely wrong and all this flying since uni has spoiled what I learnt there?:)

[Carambar]

I agree.

A coefficient is a dimensionless quantity and having gravity represented as so, doesn't sound right.

On the other hand you could calculate the lift coefficient experimentally (assuming you have the resources) by measuring the static pressure at different locations around the airfoil and integrating those over the surface area.

Another, less involved concept you could investigate is - flutter. If you place your diff airfoils in a wind tunnel and keep increasing the freestream velocity, you'll eventually reach a point where the vibrations become larger, and continue diverging if held at that speed (natural frequency). The physics can be a bit full-on but can be simplified to illustrate the basic concepts.

good luck :ok:

[Lasiorhinus]

There is a difference between gravity, and gravitivity. Gravitivity is much cooler. But it doesnt bend spacetime as much as relativity.

[mr.tos]

Coefficient of lift would be ideal. But given your circumstances, probably not applicable.

[ForkTailedDrKiller]

CaptainInsaneO, Carambar

Who said anything about gravity?

I take it you are not familiar with the Co-efficient of Gravitivity !

Note the spelling: G R A V I T I V I T Y !!

... and you call yourselves pilots !

Dr :8

PS: Sorry Pyro, I thought the "Co-efficient of Gravitivity" was a give away! I was just jerk'n ya chain! Guess I will just have to take you for a lap in the FTDK next time I am down your way - as penitance!

[Lasiorhinus]

Hoo sed pielots ar ment two bea aybel too spel?

[PyroTek]

Guess I will just have to take you for a lap in the FTDK next time I am down your way - as penitance!Hells yeah,

and, I thought you just made a typo with Gravitivity...:ok::p

[SOPS]

I could follow this thread while we has truckloads of flying birds........:ok:

[Jabawocky]

Back in the land of ADSL.......... and geez Forkie.....good fishing trip there:ok:

Almost as good as up at Karumba!:)

J

[psycho joe]

PYRO

You could determine whether it is PITCH or THRUST that controls AIRSPEED...


..I don't think the topic's ever really been discussed. :E

[ForkTailedDrKiller]

PITCH or THRUST that controls airspeed

??

Please explain?

Dr :8

[Capt Fathom]

You could determine whether it is PITCH or THRUST that controls AIRSPEED...

Neither! I control it! :E

[Gundog01]

Myth busters have run an "experiment" with a large container filled with pigeons. The container was on a set of scales and they weighed the container with all pigeons perched and all pigeons airborne.................

no difference in total weight.

[sms777]

So, there you have it!

If Myth Busters say it, you'd better believe it :E