Daft question

[Guest]

Why do boats have their props at the stern and aeroplanes (usually) have theirs in the nose?

Wouldn't displacement boats track better if they were pulled rather than pushed?

Geoff



<hr width=100% size=1>

 

[Renegade_Master]

Cos the slip stream of water created by the prop (thus creating thrust forward)would have nowhere to go cept into & against a ruddy great hull. Plus the wave cutting effect of yer bow sections would be negated.

<hr width=100% size=1><A target="_blank" HREF=http://www.suncoastmarine.co.uk>Sun Coast Sea School & Charter</A>

 

[Guest]

Doesn't the prop act like a plane one, creating lift on the front of the blade rather than thrust on the rear, thereby sucking the boat fowards?

If so wouldn't it work better in undisturbed water?

geoff

<hr width=100% size=1>

 

[Guest]

You all know that my knowledge about boats is skimpy to say the least. But I say that some of the most sucessful (weight to lift ratio) aircraft are pushed like a boat rather than pulled. This is one good example http://www.nextaircraft.com/cgw/13815141726/

<hr width=100% size=1>She made me do it

 

[hlb]

Brian it is helpfull if you put. or image [/mage] between each what...uk/weed/agifs/images83/smiling.gif[/img]Haydn

 

[longjohnsilver]

I think you've cocked up completely Haydn. Now the poor guy is completely confused and probably wondering whether you even have a boat, and if so where does Tutts keep the hefalump.

<hr width=100% size=1>

 

[ccscott49]

Your prop(s) should be in undisturbed water, if the hull is designed properly. But designing a boat with egines and props forward, might be a bit difficult in the build, but I see no reason you could not do so, but also considering the dangers of running aground and wave action, it might not be such a good idea, back there, they are protected to a certain amount and easy to install.

<hr width=100% size=1>

 

[Martin_Billings]

Not a scientist. Only got as far as melting bic biros over bunsen burners but your question made me wonder the converse: why don't more propellor driven aeroplanes have the props at the back to push them. After all, jets get pushed along by the engines.

<hr width=100% size=1>

 

[Chris_B4]

Guessing

For aeroplanes it may have something to do with intake/exhaust of the engine

The propellor sits in front of the engine intake so the engine receives an accelerated flow of air. The exhaust vents rearwards so doesn't disturb the flow across the propellor, quite critical I would think

I don't think the position matters from a thrust point of view, either way air/water has to be accelerated across the propellor and the presence of obstructions ie. hull or fuselage has the same effect whether in front or behind. In which case other considerations such as ease of build, weight distribution etc have more influence as suggested by ccscott49

(Blimey, sometimes I'm amazed at the b***s**t I can come out with when I don't really have a clue what I'm talking about)

<hr width=100% size=1>

 

[oldgit]

One of the most efficent light aircraft around designed by Burt Rutan of Scaled composits was his pusher design which resulted in the Longeze and Cozehttp://www.stevegreenair.com/long EZE.jpg

<hr width=100% size=1>My little Princess/forums/images/icons/laugh.gifthe 33 of course.Shame its not just a bit bigger.