Power required curve explanation 1

[O_antill7]

Hi there,
i am currently a 2nd year aerospace engineering student am i am stuck on the concept of power required curves! From my understanding of the equation everything component of Power required is a function of velocity and therefore as velocity tends towards 0 so too does the power required. However, when looking at every power required curve it always seems to tend towards infinity when you approach 0 velocity. Can anyone please explain why and then how i would further be able to plot the line of power require without it ending up at 0!
Thank you
Oscar
P.S I have attached my current attempt at plotting it

 

[IRstuff]

?? Every curve on your graph goes to zero at zero velocity.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm

 

[rb1957]

Yes, all are zero power and zero speed.

not sure I understand the question ?

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[O_antill7]

sorry i may not of explained myself correctly ! In theory my graphs at 0 velocity should tend towards infinity please see example image attached.

 

[BridgeSmith]

Granted, I know nothing about the subject, but it seems to me you're missing what the power required has to do. (provide a certain amount of lift, maybe?)

 

[LittleInch]

I think you need to post the equations your using a these look like GIGO to me.

How did adoubling of velocity in your top graph lead to power required giing up by a factor of ten?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[3DDave]

It appears you only included drag from boundary layer friction in your graph and did not include the induced drag from the required lift. As velocity tends to 0, the Coefficient of lift required to remain in the air goes to infinity and then so does the induced drag.

 

[rb1957]

This is a typical drag curve ...
lift induced drag falls (rather counterintuitively) as speed increases, and
profile drag (what you've labelled as "zero lift" drag) increases with speed.

produces a minimum drag at some speed (in your example at about 10 m/s).

sorry, again, what's the question ? The two pictures (1st post and 2nd post) are completely different aspects of power.



"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[IRstuff]

Sounds kind of like a paradoxical failure of the model.

For a fixed wing aircraft, lift comes from airflow over the wings, so if the wings are standing still in the air, no power is required, because you're not flying and you cannot be flying.

The equation cannot be applied below the velocity it takes for the plane to take off in the first place. Note that infinite power is not required to takeoff, either.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm