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A TALE OF TWO SECTIONS...

Be kind to our tug pilots, we cant do without them.
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chris williams
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A TALE OF TWO SECTIONS...

Post by chris williams » 06 Jul 2019, 20:38

In all the years I have been towed up by Greenley tugs, I have never seen one stall out and spin... Conversely, the 75% electric Greenley that Motley & I have built has a stall behaviour that's hairier than a Bigfoot's armpit. (Any stall under 150' and it's goodnight Vienna) You might opt for the most obvious reason: the bigger Greenley pilots know what they are doing!
It got so bad in the end that Smallpiece and I made Motley do all the towing, although I believe he's out of therapy now. Our version, although the construction methods have changed, is to all intents and purposes, the same as the original, with the same symmetrical section.
Last week I designed and built a new wing, using the tried & tested glider section HQ35, thickened to 17% to match the original design. (No washout of course) The reason? the section's tried & tested low speed behaviour.
Yesterday we tested the new wing and the results couldn't have been better. Now the model needs written permission before it will stall, and recovery is immediate. I have fitted full length flapperons, which are mixed to come up together as a landing aid, as per glider experience.

I mention this for anyone who might be designing a similar tug or sports model and would like a reasonable guarantee of good low speed behaviour.
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Barry_Cole
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Re: A TALE OF TWO SECTIONS...

Post by Barry_Cole » 06 Jul 2019, 23:40

John will no doubt reply when his apoplexy wears off.

Watch this space.

8-) 8-) 8-) 8-)

BC

john greenfield
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Re: A TALE OF TWO SECTIONS...

Post by john greenfield » 08 Jul 2019, 14:55

V interesting
Our Ampleys, which are built exactly to the free plan that is downloadable from the Ghost Squadron website are very docile. You can hold full up elevator in and they just mush along slowly sinking with not a hint of a wing drop or stall.
I have not seen the troublesome model in the flesh but would like to out of interest as clearly something is very different and maybe something got changed during the scaling process. Changing from the Standard "Greenley" fat symmetrical section to a floaty glider section will obviously change the way the mode flys .....but it is now no longer a Greenley design ?

AEB
AEB = Aeronautical Energiser Bunny (with thanks to CW)

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chris williams
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Re: A TALE OF TWO SECTIONS...

Post by chris williams » 08 Jul 2019, 17:14

I also increased the span, so now I guess it's a Williamsley... :D

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Barry_Cole
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Re: A TALE OF TWO SECTIONS...

Post by Barry_Cole » 08 Jul 2019, 17:15

It's just a Tug, get over it.....

:evil: :evil: :evil: :evil:

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Pat Marsden
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Re: A TALE OF TWO SECTIONS...

Post by Pat Marsden » 09 Jul 2019, 06:47

Barry_Cole wrote:
08 Jul 2019, 17:15
It's just a Tug, get over it.....

:evil: :evil: :evil: :evil:

BC
Oooo........I'll pull up a chair and fetch me popcorn, this could be good :D

Mark Erwood
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Re: A TALE OF TWO SECTIONS...

Post by Mark Erwood » 09 Jul 2019, 17:02

Chris, can I ask a question or two?
You say the model is a 75% Greenley. Do you mean the small Greenley which would put your model at 66" or the large Greenley which would be 75"? The other question is why scale a Greenley when you could have built an Ampley?
Just wondering!
Mark

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chris williams
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Re: A TALE OF TWO SECTIONS...

Post by chris williams » 09 Jul 2019, 17:11

Yes, 75% of the large Greenley. I seem to remember the Ampley towing up some pretty serious gliders: all we wanted to do was tow up our 5th scale stuff on 2 x 3s, so I kept the outlines, but redesigned with a lighter structure in mind...

PS Scaling model outlines in CAD is but a few minutes effort!

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Barry_Cole
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Re: A TALE OF TWO SECTIONS...

Post by Barry_Cole » 09 Jul 2019, 17:47

I just scaled the drawing and the Amply seems to be an 80% Greenly. Wing section seems identical.

However, it did fly like a dog, and now it flies like an Eagle.

We may never know why.

:shock: :shock: :shock: :shock:

BC

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Trevor
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Re: A TALE OF TWO SECTIONS...

Post by Trevor » 09 Jul 2019, 18:02

A long shot, but mysterious misbehaving wings have sometimes been tracked down to the covering lifting at the leading edge in flight. Of course it all settles down again by the time you land so isn’t easily spotted.

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