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Blade thickness question
By daleh007, Section Wind Posted on Tue Oct 26, 2004 at 12:48:52 PM MST
Does the max. thickness move towards the trailing edge as you move towards the root?

Looking at some drawings of the bottom side of a rotor it appears that the max thickness runs parallel to the leading edge. In the descriptions I've read it says to draw lines at 30% and 50% of the chord width from the leading edge. If you do this you get lines that move away from the leading edge as you approach the root. Is this correct?
Daleh

Blade thickness question | 7 comments (7 topical)

Re: Blade thickness question (3.00 / 0) (#1)
by Flux on Tue Oct 26, 2004 at 01:37:52 PM MST

Normally the max thickness stays at a fixed percentage of the blade width, usually 25 to 30%.

It may look to be parallel to the leading edge in pictures because of the twist and the way the drop on the trailing edge runs out to the thickness.

Flux

Re: Blade thickness question (3.00 / 0) (#2)
by daleh007 on Tue Oct 26, 2004 at 02:33:04 PM MST

And I assume that your statement" Normally the max thickness stays at a fixed percentage of the blade width" is talking about 25-30% of the blade width at each station?
Daleh

[ Parent ]

Re: Blade thickness question (3.00 / 0) (#3)
by Flux on Tue Oct 26, 2004 at 03:06:22 PM MST

Yes
For each station mark a point 30% of the width back from leading edge. Join these points and you have the line of maximum thickness, which you don't cut, blend the profile into it.

Flux

[ Parent ]

Re: Blade thickness question (3.00 / 0) (#4)
by DanB on Tue Oct 26, 2004 at 04:07:58 PM MST

I usually shoot to make the blade about 1/8 as thick as it is wide...
perhaps more like 1/6 as we get towards the root. 25, or 30% seems way too thick to me.

[ Parent ]

Re: Blade thickness question (3.00 / 0) (#5)
by daleh007 on Tue Oct 26, 2004 at 05:47:41 PM MST

25-30% was referring to the cord width behind the leading edge at which the max. thickness is measured. Guess I didn't make this clear in my follow up statement.
Daleh

[ Parent ]

Re: Blade thickness question (3.00 / 0) (#6)
by twombo on Fri Nov 05, 2004 at 11:25:55 AM MST

How much washout... 3 or 4 degrees?

Re: Blade thickness question (3.00 / 0) (#7)
by daleh007 on Wed Nov 10, 2004 at 12:01:03 AM MST

what is washout? I haven't heard this term yet.
Daleh

[ Parent ]

Blade thickness question | 7 comments (7 topical)

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