Welcome Guest
HeliTorque
  
User Control Panel

Security Code: : Security Code
Type Security Code Here: :
 
Register Here
Lost Password?

Online Stats:
Visitors: 44
Members: 0
Total: 44

Membership:
New Today: 0
New Yesterday: 0
Registering: 0
Members: 6662
Latest: chrisw

Most Ever Online
Visitors: 447
Members: 10
Total: 457


HeliTorque :: View topic - Induced Flow in the Free Air Hover
Forum FAQ
Forum FAQ
Search
Search
Memberlist
Memberlist
Usergroups
Usergroups
Profile
Profile
Contact Manager
Contact Manager
Log in
Log in
Log in to check your private messages
Log in to check your private messages
HeliTorque Forum Index » Flight Dynamics

Post new topic   Reply to topic All times are GMT
Induced Flow in the Free Air Hover Goto page Previous  1, 2
View previous topic :: View next topic  
Author Message
WhirlyGirl
Administrator
Administrator


Offline
Joined: Jul 20, 2004
Posts: 3702
Location: Birmingham, UK


uk.gif

PostPosted: Fri Jul 07, 2006 6:12 pm    Post subject: Reply with quote

Paco,

I searched that AGK info you sent me trying to find something on this, but I'm guessing it's more of a Principles of Flight question (as it is in my syllabus too). Would you mind explaining why you thought C? I would really like to understand the effect that the tip vortices have on the Vi, and it would be great to have some explain it in a way that makes some sense! Laughing

WhirlyGirl Cool
_________________
CPL(H) / FI(H) - Cabri G2, R22, S300, R44, B206
Flight Examiner (H), Ground Examiner (H)
Back to top
View user's profile Send private message Visit poster's website Skype Name
paco
'Torquing Regularly
'Torquing Regularly


Offline
Joined: May 14, 2005
Posts: 90
Location: Wycombe Air Park, Calgary, Dubai


canada.gif

PostPosted: Sat Jul 08, 2006 2:50 am    Post subject: Reply with quote

I think some clue lies in the question. Like the diagram above, the induced flow is most at the tips because the blades are flying faster there, but not because of tip vortices, so answer a is out.

Answer B is b*llocks.

Induced flow is fastest when vertical through the disk (actually just below). Tip vortices (like you get with any aerofoil producing lift) cause the downwash to leak away, so the induced flow becomes less vertical round the edge of the disk as it is sucked in from outside, and therefore has less effect. One of the reasons that ground effect works is that tip vortices are reduced and the disk becomes more efficient, so that answer about GE in the exam about divergent ducts is more right than the other answers, even though it sounds strange (the other is that induced flow is reduced).

Recirculation makes air flow faster, and is a symptom of being near the ground and you are in a free air hover, so D is out.

Why can't they ask straightforward questions?

Phil
Back to top
View user's profile Send private message Visit poster's website Skype Name
WhirlyGirl
Administrator
Administrator


Offline
Joined: Jul 20, 2004
Posts: 3702
Location: Birmingham, UK


uk.gif

PostPosted: Tue Jul 11, 2006 3:42 pm    Post subject: Reply with quote

Well, it didn't come up in the exam - in fact none of the questions I asked about did! I found the standard of the questions very high, and in a format that differed from the way they had been asked in feedback questions I'd seen. Hopefully the logic I applied to obtain the answers was correct!

Many thanks to everyone for your help and input all the same - now I have to suffer for 2 weeks until they send the result through.

WhirlyGirl Cool
_________________
CPL(H) / FI(H) - Cabri G2, R22, S300, R44, B206
Flight Examiner (H), Ground Examiner (H)
Back to top
View user's profile Send private message Visit poster's website Skype Name
James T Lowe
Moderator
Moderator


Offline
Joined: Jul 27, 2004
Posts: 2575
Location: Leicester


uk.gif

PostPosted: Tue Jul 11, 2006 4:25 pm    Post subject: Reply with quote

Oh yes! That was today, wasn't it? How did the exams go? Do you feel you've done well? Smile
_________________
J.
Back to top
View user's profile Send private message Visit poster's website
WhirlyGirl
Administrator
Administrator


Offline
Joined: Jul 20, 2004
Posts: 3702
Location: Birmingham, UK


uk.gif

PostPosted: Tue Jul 11, 2006 5:01 pm    Post subject: Reply with quote

It was yesterday - the general opinion was that it was a hard paper, but we'll just have to wait and see what happens!

WhirlyGirl Cool
_________________
CPL(H) / FI(H) - Cabri G2, R22, S300, R44, B206
Flight Examiner (H), Ground Examiner (H)
Back to top
View user's profile Send private message Visit poster's website Skype Name
Display posts from previous:   
Post new topic   Reply to topic    HeliTorque Forum Index » Flight Dynamics All times are GMT

 
Goto page Previous  1, 2
Page 2 of 2

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Sponsors


Billund Air Center

Visit HeliTorque!