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Pat Teakle Asw 22 6m

Let us all watch your new project progress.
Dave Mackintosh
Posts: 43
Joined: 26 Dec 2020, 19:02
Location: Cambridgeshire

Re: Pat Teakle Asw 22 6m

Post by Dave Mackintosh »

Good evening folks.
My progress so far, all panels except the tips are cut. I had to cut 4 panels for the mid section, as at the moment I can only cut up to 1030mm at a time.(The mid panels are around 120mm wider).
I will cut the tip panels tomorrow night.
Cheers.
Attachments
4panel.jpg
panel2.jpg
cnc.jpg

Dave Mackintosh
Posts: 43
Joined: 26 Dec 2020, 19:02
Location: Cambridgeshire

Re: Pat Teakle Asw 22 6m

Post by Dave Mackintosh »

The tip panels now complete the foam cutting phase. I am now turning my attention to spar and joiner sytems.
Cheers.

User avatar
larrikin
Posts: 17
Joined: 29 Nov 2015, 01:39

Re: Pat Teakle Asw 22 6m

Post by larrikin »

Hi Dave
I’m keen to see what you do by way of spars.
I have my own ‘22 build happening but I confess to have balked at this “spar sizing” stage.
What’s your priority, ultimate strength/stiffness or scale-like flex?

https://www.rcgroups.com/forums/showthr ... om-Scratch

David.
Avatar is K7 VH-GQX in 1980.

Dave Mackintosh
Posts: 43
Joined: 26 Dec 2020, 19:02
Location: Cambridgeshire

Re: Pat Teakle Asw 22 6m

Post by Dave Mackintosh »

larrikin wrote:
17 Mar 2021, 23:38
Hi Dave
I’m keen to see what you do by way of spars.
I have my own ‘22 build happening but I confess to have balked at this “spar sizing” stage.
What’s your priority, ultimate strength/stiffness or scale-like flex?

https://www.rcgroups.com/forums/showthr ... om-Scratch

David.
Hi David, Great build thread!
I would like a bit of both? I won't be stressing the airframe too much,as I fly like an old duffer theses days.What are your thoughts? My first thought is a near full span carbon faced 2mm spar,with a tapering cap.
Cheers.
Dave.

User avatar
larrikin
Posts: 17
Joined: 29 Nov 2015, 01:39

Re: Pat Teakle Asw 22 6m

Post by larrikin »

Hi Dave,
What are my thoughts?
You might regret asking that one. :)
As you're about to experience, I'm the classic over-thinker and you'll be flying yours while I'm still pondering mine ... 5 years from now. :oops:

I place a huge importance on torsional stiffness and this will be handled by carbon cloth at +/-45 under a timber veneer skin.
It's the bending stiffness vs strength that has me pondering.
Each time I think I'm happy with a spar arrangement, I recall the Southern Sailplanes Kestrel 17. http://members.optusnet.com.au/~rlearmont/Kestrel.html.
It uses/used a foam core with balsa skins and ZERO spar. Nothing!
And, from memory, there was an aluminium tube only about 200mm long that accepted the joiner rod, the end of which wasn't supported by anything other than the foam core. There may have been a web on one side of the aluminium tube to the top or bottom skin to fill a slot from the hole cutting process where the tube goes into the core, but that was it.
Yes, it's "only" 4.25m span, but I saw a few of these fly and none of them failed during loops or winch launches. The wing flex was a load indicator and the elevator was adjusted accordingly.
I too will be flying my '22 like "an old duffer" with the occasional low-level, high-speed pass, but I have no intention of high "G" manoeuvres.
I used the word "intention" deliberately. Where my quandary lies is, do I account for the unintended "G" manoeuvres that may never happen.
I've seen some funky stuff happen to sailplanes on tow when the tow goes pear-shaped.

I've chosen to make the wing in 6 panels. What I'm thinking is to use a spar/web setup for the root panels, then use Drela-style weblets instead of the spar for the mid and tip panels. Remembering that there's a timber veneer 'stressed skin' to add bending stiffness, too.

David.
Avatar is K7 VH-GQX in 1980.

roo Hawkins
Posts: 868
Joined: 18 Mar 2015, 20:12
Location: Northamptonshire

Re: Pat Teakle Asw 22 6m

Post by roo Hawkins »

One of the ways I do spars on my pat teakle gliders is a wood spar of about 6 mm and glass carbon tows on to each one .I stick pins in and go around them with carbon tow canot do 4 spars in about a hour. After fixing in the wing I add a ply web sometimes with a carbon tape on..I place the carbon side of the spar down side in to the wings and sometimes I lay a carbon spread tow on top. That is my simple method on bigger models I will do the same but with a full carbon d box. The original pat teakle gliders only add two spars in the wing.so the wings flexed a bit too much. But few great.

Dave Mackintosh
Posts: 43
Joined: 26 Dec 2020, 19:02
Location: Cambridgeshire

Re: Pat Teakle Asw 22 6m

Post by Dave Mackintosh »

larrikin wrote:
18 Mar 2021, 09:04
Hi Dave,
What are my thoughts?
You might regret asking that one. :)
As you're about to experience, I'm the classic over-thinker and you'll be flying yours while I'm still pondering mine ... 5 years from now. :oops:

I place a huge importance on torsional stiffness and this will be handled by carbon cloth at +/-45 under a timber veneer skin.
It's the bending stiffness vs strength that has me pondering.
Each time I think I'm happy with a spar arrangement, I recall the Southern Sailplanes Kestrel 17. http://members.optusnet.com.au/~rlearmont/Kestrel.html.
It uses/used a foam core with balsa skins and ZERO spar. Nothing!
And, from memory, there was an aluminium tube only about 200mm long that accepted the joiner rod, the end of which wasn't supported by anything other than the foam core. There may have been a web on one side of the aluminium tube to the top or bottom skin to fill a slot from the hole cutting process where the tube goes into the core, but that was it.
Yes, it's "only" 4.25m span, but I saw a few of these fly and none of them failed during loops or winch launches. The wing flex was a load indicator and the elevator was adjusted accordingly.
I too will be flying my '22 like "an old duffer" with the occasional low-level, high-speed pass, but I have no intention of high "G" manoeuvres.
I used the word "intention" deliberately. Where my quandary lies is, do I account for the unintended "G" manoeuvres that may never happen.
I've seen some funky stuff happen to sailplanes on tow when the tow goes pear-shaped.

I've chosen to make the wing in 6 panels. What I'm thinking is to use a spar/web setup for the root panels, then use Drela-style weblets instead of the spar for the mid and tip panels. Remembering that there's a timber veneer 'stressed skin' to add bending stiffness, too.

David.
Thanks David, Food for thought. I am hatching a plan and will have some pics soon. Something along the lines of the built up Pat Teakle wing. With a tweak or two.
Dave.

Dave Mackintosh
Posts: 43
Joined: 26 Dec 2020, 19:02
Location: Cambridgeshire

Re: Pat Teakle Asw 22 6m

Post by Dave Mackintosh »

roo Hawkins wrote:
18 Mar 2021, 11:43
One of the ways I do spars on my pat teakle gliders is a wood spar of about 6 mm and glass carbon tows on to each one .I stick pins in and go around them with carbon tow canot do 4 spars in about a hour. After fixing in the wing I add a ply web sometimes with a carbon tape on..I place the carbon side of the spar down side in to the wings and sometimes I lay a carbon spread tow on top. That is my simple method on bigger models I will do the same but with a full carbon d box. The original pat teakle gliders only add two spars in the wing.so the wings flexed a bit too much. But few great.
Many thanks Roo.Great info.
Dave.

User avatar
larrikin
Posts: 17
Joined: 29 Nov 2015, 01:39

Re: Pat Teakle Asw 22 6m

Post by larrikin »

Correction.

I was incorrect about the spar arrangement of the Kestrel.
The receiving tube for the joiner bar was ~300mm in length and did have a supporting plywood sub-rib at the end of the tube.
Aged and confused,
David
Avatar is K7 VH-GQX in 1980.

Dave Mackintosh
Posts: 43
Joined: 26 Dec 2020, 19:02
Location: Cambridgeshire

Re: Pat Teakle Asw 22 6m

Post by Dave Mackintosh »

Evening Chaps.
Progress so far.
Plenty of work still to be done.
Attachments
rigged.jpg
twinspar.jpg
joiner.jpg

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