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Old Dec 29, 2011, 08:09 PM
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Vernon Hunt's Avatar
Florida
Joined Mar 2005
806 Posts
Biber has it spot on. From what I've read 25 deg. of sweep or more needs anhedral. My DLG wing has 30 deg. of sweep and needed 1.5 deg. of anhedral per side and thats only a 60" wing.

Vern
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Old Dec 29, 2011, 10:54 PM
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nmasters's Avatar
Colorado
Joined Aug 2006
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Quote:
Originally Posted by biber View Post
sweep does act like dihedral, whenever the swept wing does create lift. So at low speed, the dihedral effect of the sweep contributes noticably to the whole and at high speed it hardly does at all.

With sweep and winglets you have lots of effective dihedral already and in many cases less would be better.
Then you build some anhedral into it to have just the needed amount.
Here's an article on the dihedral effect due to sweep.

--Norm
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Old Dec 30, 2011, 02:59 AM
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miniphase's Avatar
Kent, UK
Joined Nov 2004
870 Posts
Quote:
Originally Posted by Vernon Hunt View Post
Paul,


How's your thermal wing coming along?

Vern
I'm powering on with decorating at the moment but I'll start heating up my hot wire in a few weeks and move the thread across to this forum
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Old Dec 31, 2011, 09:39 AM
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Vernon Hunt's Avatar
Florida
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806 Posts
Paul,

I can't wait to see the finished product. I got the servos in and the fuselage glassed. I hope to glue this pod on today and start the finish. I do have a set of cores for a Horten style wing I cut 3 years ago. Maybe I otta press some balsa on them and see how it flys.

Vern
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Old Dec 31, 2011, 10:43 AM
less is more
Knoll53's Avatar
United States, CA, Marina
Joined Sep 2006
2,851 Posts
Vern,

I broke out my magnifying glass and I could not see any control surfaces near the root. Does this ship fly with Elevons only?

Also, at 100" wing span, this puppy could float. Do see a need for any sort glide path control?

Kent
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Old Dec 31, 2011, 10:53 AM
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Vernon Hunt's Avatar
Florida
Joined Mar 2005
806 Posts
Kent,

I have found that flaps is luxury that a light glider like this does'nt need. Saves weight. At a good field without trees in the way I can land it predictably at my feet.... most of the time. Gotta plan ahead.

Vern
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Old Dec 31, 2011, 11:47 AM
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Florida
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806 Posts
Heres what I've got as of noon today. Looks like it might be a good flyer....

Vern
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Old Dec 31, 2011, 12:01 PM
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miniphase's Avatar
Kent, UK
Joined Nov 2004
870 Posts
As it doesn't fit in the car, you'll be walking to the field with this beauty then Vern?

Also can we request some movie of the launches? I'd love to to see how she goes up the line.
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Old Dec 31, 2011, 12:23 PM
Deniable plausibility
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Derbyshire, UK
Joined Aug 2008
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Very elegant wing you have there. Nice one.

Happy New Year!
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Old Dec 31, 2011, 01:22 PM
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Vernon Hunt's Avatar
Florida
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806 Posts
Paul,

Yes, I will be walking...... not, I will have to keep the rear door open cause it sticks out the back about 12". I wanted to save as much weight as I could, so I glued the thing together. There are trade-offs that have to be made when one has very little money.

Thanks Shedofdread

Happy New Year!

Vern
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Old Dec 31, 2011, 01:23 PM
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Vernon Hunt's Avatar
Florida
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Originally Posted by Vernon Hunt View Post
Paul,

Yes, I will be walking...... not, I will have to keep the rear door open cause it sticks out the back about 12". I wanted to save as much weight as I could, so I glued the thing together. There are trade-offs that have to be made when one has very little money.

Thanks Shedofdread

Happy New Year!

Vern
Vids will be available
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Old Jan 01, 2012, 12:28 PM
Designing something...
United States, CA, Cameron Park
Joined Jan 2004
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Quote:
Originally Posted by Vernon Hunt View Post
Heres what I've got as of noon today. Looks like it might be a good flyer....

Vern
She looks good Vern.

Brian
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Old Jan 01, 2012, 05:47 PM
Deniable plausibility
Shedofdread's Avatar
Derbyshire, UK
Joined Aug 2008
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Quote:
Originally Posted by nmasters View Post
Here's an article on the dihedral effect due to sweep.

--Norm
OK, I've clearly overdone the mince pies and mulled wine but if one uses the formula on p14 to get the effective dihedral for the Co8 design described at the end of ther document, I certainly don't get the 1.5deg that's quoted.

Would someone be so kind as to run that calc themselves and see what they get. It's driving me nuts.

Many thanks (he said, off to somewhere quiet...)
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Old Jan 02, 2012, 09:48 AM
less is more
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United States, CA, Marina
Joined Sep 2006
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Quote:
Originally Posted by Shedofdread View Post
Would someone be so kind as to run that calc themselves and see what they get. It's driving me nuts.)
I had the same experience. It's a slippery subject. What bothers me about such technical papers is that they sometimes state a formula without showing how it was derived. In structural design this would be unacceptable. A formula may be just an estimate of an observation. Not knowing where the formula came from leaves me in the dark.

With that said, it was a good article. I learned a lot. For me, I had my answer with biber's post #30. I know, I know....how much anhedral is needed.....

Kent
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Old Jan 02, 2012, 10:06 AM
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United States, CA, Marina
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Vern,

You appear to have a knack for building light planes. You have a big balsa end cap at the tip that you mount the winglet to. Is this structure wrapped in FRP or does just the wood get the job done?

I do not believe that I have ever built a wing with big winglets, but I would think that I would be snapping them off on a regular basis. I fly at steep slope sites with tiny LZ's that do not always lend themselves to upright landings.

Kent
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