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Teakle ASW 20 3.5/1

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Martin Church
Posts: 74
Joined: 06 Oct 2015, 11:23
Location: Somerset edge of Mendips

Re: Teakle ASW 20 3.5/1

Post by Martin Church »

I bought the vac bagged wing cliff & very impressive it is.

Martin Church
Posts: 74
Joined: 06 Oct 2015, 11:23
Location: Somerset edge of Mendips

Re: Teakle ASW 20 3.5/1

Post by Martin Church »

Hi again guys as I've never built anything quite like this Could anyone help me with a method of getting the leading edge to the correct section?
I spoke to pat on Sunday & he told me the section was a Ritz 3 but how I go about making templates to ensure the correct section at the front I havent a scooby doo! I have rough shaped them with a davids razor plane & a sanding block but need to finish them to correct profile.
Pictures attached.
Anyone have a complete idiot proof way of acheiving this?
Thanks very much in advance.
Martin Church
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RobbieB
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Location: North West
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Re: Teakle ASW 20 3.5/1

Post by RobbieB »

Martin, to have a super accurate LE on a scale sailplane is probably not necessary. Yes, the most critical part of any working aerofoil but at these scales, these flying speeds and the required flight characteristics you are unlikely to notice any difference as a consequence of slight variations in the form.

What is important, to get the best out of the selected aerofoil is to ensure the entry level point (the actual position of the LE point) is in the correct position and consistent throughout the span. This will also, to a large degree, determine the smooth transition around the LE from top to bottom.

My method of ensuring this is to draw a line in the correct position on the LE material the full length of the wing and make sure that it remains visible all the way through the planing and sanding phase right up to the final fine grade sandpaper stage.

If you are flying in F3F, F3B etc at the very highest level then that might be a different kettle of fish altogether but on your present model I think accuracy of that degree will matter not a jot.

If you need a copy of the Ritz profile under normal circumstances I could whizz one over to you but unfortunately I'm on my jollies at the moment and I don't have a copy of my aerofoil programme on the laptop - perhaps someone else can come up with one in the meantime but I think there should be some other numbers after the 3, something like Ritz 3-30-10.

Martin Church
Posts: 74
Joined: 06 Oct 2015, 11:23
Location: Somerset edge of Mendips

Re: Teakle ASW 20 3.5/1

Post by Martin Church »

Thanks Robbie
Is my best bet then to take the profile from the fuselage root profile & shrink it down to the chord at the tip? This may give me a centre line I can work to.
Regards Martin

Martin Church
Posts: 74
Joined: 06 Oct 2015, 11:23
Location: Somerset edge of Mendips

Re: Teakle ASW 20 3.5/1

Post by Martin Church »

Thanks Cliff
Can I scale that up & down on a printer to get the chord or doesn't it work that way?

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RobbieB
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Re: Teakle ASW 20 3.5/1

Post by RobbieB »

Martin,

Pat will surely have made the root moulding on the fuz to match the wing aerofoil so that would a good way to go.

A few words of caution. The aerofoil I stated in the earlier post was only an example of Ritz nomenclature and not necessarily the one on the ASW - in fact I think it rather unlikely for Pat to have chosen one to be that thin as shown in Cliff's drawing above. I've never used the Ritz section so I'm not familiar with the numbers but I'm guessing the first one is the camber, the second is either the point of maximum camber or thickness and the third the percentage thickness. Perhaps someone can put me right on those. Again I would guess it might be something more like Ritz 3-30-12 or14 perhaps.

Also, Pat may have changed the section towards the tip and that could change the entry point so best check on that.

Cliff might have more info on all of this.

Martin Church
Posts: 74
Joined: 06 Oct 2015, 11:23
Location: Somerset edge of Mendips

Re: Teakle ASW 20 3.5/1

Post by Martin Church »

Thanks to you both for replying.
I will do a little more digging.
Maybe I need to get win foil & my graph paper out.
Martin

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Peter Balcombe
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Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: Teakle ASW 20 3.5/1

Post by Peter Balcombe »

Martin,
I have just spoken to Pat who confirms that both the Vega and ASW20 used the Ritz 3.0 section, but he can't remember the thickness numbers.
Anyway, I wouldn't get too hung up about this as you will be fine if you do what Robbie suggested & draw a line down the LE where the nose line is, rough back & sand to profile by eye, using the wing core profiles as a guide.
That is what I did, & Pat did exactly the same.
My 20 flies very nicely without having checked the profile accuracy.
Hope you get it flying soon.
Peter

Martin Church
Posts: 74
Joined: 06 Oct 2015, 11:23
Location: Somerset edge of Mendips

Re: Teakle ASW 20 3.5/1

Post by Martin Church »

Ok cheers peter I did see pat Sunday when I visited to pay my membership. Hopefully may see you up there sometime soon.

Martin Church
Posts: 74
Joined: 06 Oct 2015, 11:23
Location: Somerset edge of Mendips

Re: Teakle ASW 20 3.5/1

Post by Martin Church »

It's been a productive week.
One wing with leading edge now shaped airbrake in & capped & all aileron & flap faces capped. Need to add wing tip block & shape. I'm going to leave it full span 190" & mock up the extension join. I am however unsure if I need to glass these wings or not. They are the epoxy vac bagged wings but I will be flying it from crooks peak so I need a very durable finish. So tonight I've picked up the other wing & attached the Ramin leading edge.
One thing is for sure this is a big old Glider. I realised this after picking up a 1/4 Pik 20 on Friday & with both fuselages together it certainly shows its size.
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