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Motor Falke ¼ scale - Cliff Charlesworth.

Let us all watch your new project progress.
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Peter Balcombe
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Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: Motor Falke ¼ scale - Cliff Charlesworth.

Post by Peter Balcombe »

Max,
No, if you look at the first wing build post (28 Nov?), you will see that I used my normal build method - build wing up from lower main spar, notching each rib onto the spar.
If the ribs didn’t have notches as laser cut then I would have cut them by hand.
The build log post says that I built the ribs onto the bottom spar, raising the outer TE by 5mm? as required for the washout.
The photo shows the intact rib section between the spars to confirm the above.

The Cliff Charlesworth method of build was to make up a spar box & then slice out this section of each full rib to suit - meaning that the cut angles had to be different, but correct in order to avoid a wavy TE.
However, it is easy enough to mark the spar position on each rib from the plan & then notch each rib top & bottom. I can’t recall if the spars taper, but this can be worked out & taken into account in the notching.
The ribs can then be placed with TE at the correct level along the span to get straight TE lines.
Peter

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Max Wright
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Joined: 10 Mar 2020, 19:57
Location: Clayton Bay South Australia

Re: Motor Falke ¼ scale - Cliff Charlesworth.

Post by Max Wright »

I'm confusing myself by reading Trevor's build log and your thread on the SF-33.

They are two different aircraft, but I took it that the spar design was common.

This is a shot from 18th March, 2015 . . .

Wing root.jpg
Wing root.jpg (6.42 KiB) Viewed 196 times

It looks like you've left filling in the spaces in the vertical sides of the spar until later.
Max

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

Re: Motor Falke ¼ scale - Cliff Charlesworth.

Post by Peter Balcombe »

Max,
Yes. If you notch the ribs to sit the ribs onto the bottom spar and drop in the top spar, you need to complete the box by adding vertical grain spar webs between each rib.
Photo of spoiler area posted on 12th Jan 2019 shows the spar webs in that area.

To get the full box spar equivalent you add webs front& back, but the benefit is that:
a) the webs don’t necessarily need to fill 100% of the inter-rib gap;
b) the webs can more easily be vertical grain - stronger than horizontal grain.
c) you can more easily get at front & rear of the assembled joiner area to block this in - solidly bonding joiner to spars.

The whole point of the box section is to tie the two spars together to make the spar system resistant to higher bending loads - however that is achieved. Note that many wing designs use just a front or rear web to achieve a similar objective, saving weight but not quite as strong.

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Max Wright
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Location: Clayton Bay South Australia

Re: Motor Falke ¼ scale - Cliff Charlesworth.

Post by Max Wright »

Ah. Thanks, Peter.

I guess a spar is like a truss; in that in a truss, the vertical sides actually have spaces - or is some cases the vertical is just a rod bent into a row of z'ds.

What occurs to me is, that if there are spaces the spar could become the conduit for the wing servos.

Cheers
Max

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Peter Balcombe
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Location: Clevedon, North Somerset, U.K.

Re: Motor Falke ¼ scale - Cliff Charlesworth.

Post by Peter Balcombe »

Max Wright wrote:
13 Oct 2020, 00:27

What occurs to me is, that if there are spaces the spar could become the conduit for the wing servos.

Cheers
Max, if you mean using the spar box for servo cable routing - then yes no problem, although the root section should be fairly solid around the joiner so just exit the box just before you get there.

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Max Wright
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Location: Clayton Bay South Australia

Re: Motor Falke ¼ scale - Cliff Charlesworth.

Post by Max Wright »

Sorry, Pete.

I should use the Smilies. :oops:

Not everyone gets my humour.

Thanks for your interest.
Max

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Barry_Cole
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Joined: 10 Mar 2015, 09:30
Location: Hampshire UK

Re: Motor Falke ¼ scale - Cliff Charlesworth.

Post by Barry_Cole »

Seemed like a sensible idea to me...

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

BC

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Max Wright
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Joined: 10 Mar 2020, 19:57
Location: Clayton Bay South Australia

Re: Motor Falke ¼ scale - Cliff Charlesworth.

Post by Max Wright »

Many a true word . . .

I'm starting to like it, Baz. ;)
Max

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Max Wright
Posts: 103
Joined: 10 Mar 2020, 19:57
Location: Clayton Bay South Australia

Re: Motor Falke ¼ scale - Cliff Charlesworth.

Post by Max Wright »

This afternoon, the Graupner wing joiners and the extra magnets arrived. I've got some more spruce to make the aft wing spar, so I should be able to make a start.

T-61A 3.JPG

I can't get my head around the crank at the root end of the wing and the wash out at the tip.

The plan says that the leading edge has to remain flat on the building board right across. So if I raise the trailing ends of the relevant ribs, they will lift off the spar.

I'll read all of my reference material again to see if I can glean the meaning. In the meantime, feel free to join in. :)

Cheers
Max

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Cliff Evans
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Re: Motor Falke ¼ scale - Cliff Charlesworth.

Post by Cliff Evans »

Max, the way the wing is constructed, the ribs will not lift off of the spar. If you have Cliffs book, Fig 39 on page 74 and Fig 15,16 and 17 on pages 140 - 141 shows how he constructs the wing. If you have not got the book, scans of those pages are below. The box spar is made and the ribs are cut to size from the blanks for forward and aft riblets. Washout on the falk is from rib 16 (the aileron break) to the tip. I feel sure others will join in.
img009.jpg
img006.jpg
img008.jpg
Laser Cut sailplanes

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