*


All times are UTC + 1 hour



Post new topic Reply to topic
 [ 1 post ] 
Author Message
 Post subject: Some "dynamic" basics...
PostPosted: Sat Sep 28, 2013 10:15 pm 
Offline
Very Frequent Poster
User avatar

Joined: Wed Oct 16, 2002 1:00 am
Posts: 5638
Location: Denmark
Hi

Making a foil "lift" earlier, is NOT always a wanted feature...

It seems that many who does not foil, think so ?

If you got a big foilwing, with lots of camber - it will lift at much lower speeds, true.

BUT, so what - as it will also have a lot more drag, thus never get much speed, thus never giver a good upwind (nor downwind) VMG either, so bad bad bad in all situations.

Having a foilwing with very little camber, a thin profile, and small area - will lift a lot later of course (higher speed needed).
But it will be A LOT faster straight out no matter what, and regarding upwind VMG there will be a certain point where the size/lift will be maxed so to speak.
Not too much, nor too little :rollgrin:
The downside is when manoeuvering - then you will not be able to foil as good (easy and long), when turning and tacking and so on - if too low lift.
The upside can be that it can be easier controllable at very high speeds - depending on the outline and angles.

So it is a balance.


The same goes for low AR versus high AR foils.

The low AR are much easier to ride, and not nearly as sensitive - so good for beginners and for easy tricks/turns.
But they will have more drag, so not as fast.


Then you got the long versus short wing-wing distance.

Short = more manoeuverable but not as stable.


Finally, you got the change in AOA on the front wing, from center to tip.
This is what we call wash-out in flying terms, in order to avoid tip stalling in turns.
On a hydrofoil, that is slightly swept, this change in AOA will make the foil much more selfstable and easy to ride.
But the cost, is higher drag at high speeds (low AOA's) especially.

Again - a horses for courses situation.


Just a few very basic things, that seem to confuse many - as some think it is about to foil as early as possible :roll:

Which is not the case - there are many other choices to be aware of.

Kindly, Peter Frank


{ SHARE_ON_FACEBOOK } { SHARE_ON_TWITTER } { SHARE_ON_ORKUT } { SHARE_ON_DIGG } { SHARE_ON_MYSPACE } { SHARE_ON_DELICIOUS }
Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic
 [ 1 post ] 

All times are UTC + 1 hour


Who is online

Users browsing this forum: Tone and 1 guest


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 post attachments in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group