Scale Soaring UK

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.

John will no doubt reply when his apoplexy wears off.

Watch this space.



BC

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

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

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



BC

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



BC

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

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

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!

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.



BC

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.

Thanks for the info Chris. Part of my interest was that I had been considering an Ampley. Well I've got a spare motor and a 10s battery pack so it seems logical?? You say that you lightened the structure - what about torsional rigidity of the wing? Lack of could have some funny effects.
Mark

As many of you will know i have an SDD ( 100" Greenley ) an SD ( 88" Greenley ) and also 2 Ampleys. One of the Ampleys was lightened and nicknamed a Milliamp and flies around very well on a 4s battery for my wifey to have a stooge around with. The other is a tug, powered by 8s and can easily pull a 4mtr glider whilst still being docile enough for my wife to fly. Neither the Ampley or the Milliamp show any nasty handling characteristics associated with a stall and will both come in slow and at high angle of attack, effectively landing on the tailwheel first.
Would be interesting to find out why the plane in question exhibits the nasty stall. As AEB is about to embark on a tour of europe whilst us brits are still welcomed it may be a while until he responds further so I guess I had better stock up on popcorn and cider

Mark Erwood wrote: ↑09 Jul 2019, 18:44 Thanks for the info Chris. Part of my interest was that I had been considering an Ampley. Well I've got a spare motor and a 10s battery pack so it seems logical?? You say that you lightened the structure - what about torsional rigidity of the wing? Lack of could have some funny effects.
Mark

Mark

Build an Ampley from the plans and you will have no problem, John has an Ampley running a 10s setup that is quite tame......just remember to throttle back quick if you get a line break on take off otherwise it might try and torque roll itself into terra firma

what about torsional rigidity of the wing? Lack of could have some funny effects.

It would be quite difficult,even for me, to build a wing that thick and with such a short span without sufficient torsional rigidity. It's worth pointing out that it also survived three plunges into the well known terror firmer...The wing is now surplus to requirements and is looking for a good home

What I think it could be, having studied aerostromatics, is that the wing, could have been put on upside down!!

terry white wrote: ↑13 Jul 2019, 16:18 What I think it could be, having studied aerostromatics, is that the wing, could have been put on upside down!!

Typical isn't it, just when you think you are getting the hang of things, really getting a handle on stuff, someone goes all technical on you...............

When you've sorted out 'what's watt' someone might like to give Geoff Pearce a hand and advice preparing his new scale tug?

It's all happening out there!

M

MDev wrote: ↑31 Jul 2019, 09:17 When you've sorted out 'what's watt' someone might like to give Geoff Pearce a hand and advice preparing his new scale tug?

It's all happening out there!

M

How did I get dragged into this?

Kicking and screaming like the rest of us......



BC

MDev wrote: ↑31 Jul 2019, 09:17 When you've sorted out 'what's watt' someone might like to give Geoff Pearce a hand and advice preparing his new scale tug?

It's all happening out there!

M

Mark, had Geoff asked then help would be given. We are not psycic you know As it happens Geoff did ring me today anyway.

You bypassed the humorous bit Pat, I'll tell you at Binham.

M

MDev wrote: ↑04 Aug 2019, 11:39 You bypassed the humorous bit Pat, I'll tell you at Binham.

M

Not so much bypassed as missed it completely then, looking forward to it being explained

Geoff, If it involves flaps, don`t ask Pat, Just a waste of 2 good servos
T.

Tonyh wrote: ↑09 Aug 2019, 21:37 Geoff, If it involves flaps, don`t ask Pat, Just a waste of 2 good servos
T.

Yeah, dont bother with them Geoff, I rarely use them on my Greenleys much to the annoyance of a certain person

Cliff Evans wrote: ↑10 Aug 2019, 19:37

Pat Marsden wrote: ↑10 Aug 2019, 16:03

Tonyh wrote: ↑09 Aug 2019, 21:37 Geoff, If it involves flaps, don`t ask Pat, Just a waste of 2 good servos
T.

Yeah, dont bother with them Geoff, I rarely use them on my Greenleys much to the annoyance of a certain person

He watches you know Pat!

Yes, I know Cliff

Pat Marsden wrote: ↑11 Aug 2019, 06:12

Cliff Evans wrote: ↑10 Aug 2019, 19:37

Pat Marsden wrote: ↑10 Aug 2019, 16:03
Yeah, dont bother with them Geoff, I rarely use them on my Greenleys much to the annoyance of a certain person

He watches you know Pat!

Yes, I know Cliff

I am

AEB