SLINGSBY DART 17R 1/3 SCALE

cw · Posté le: 08/07/2008 21:59 Sujet du message: SLINGSBY DART 17R 1/3 SCALE

I am building a 3rd scale version of the Dart 17R from my 1:3.5 scale plan, hopefully for Retroplane 2009...

1:3.5

1:3.5

3rd scale: building the spar. The Dart has 2 wing panels, but they are too big for my small workshop. So, I am building the wing in 3 sections, a la Skylark 4. The spar for the centre wing panel has 12 x 6mm spruce each side of a central 1.5mm ply web to form a classic 'I' beam

Checking the fit against the centre fuselage formers...

Laurent Beldame · Posté le: 08/07/2008 22:55 Sujet du message:

Quite promising Mr Williiams.......should be even more forgiving than the Skylark 4 (if you remember some comments heard at the Schweisel) Wink

Cheers

cw · Posté le: 08/07/2008 23:12 Sujet du message:

Laurent, there were many comments made at the Schweisel, which ones do you mean...? Confused

Laurent Beldame · Posté le: 09/07/2008 08:31 Sujet du message:

...the one for which the consequence was to have your transmitter landing in my hands to fly the Skylark...nice souvenir Wink

L

Walter · Incurable Posteur Inscrit le: 05 Nov 2006

..."Quick Chris" is here... Wink

Hello Chris,

...welcome to the retroplane forum - good to have you and your phantastic planes here...

I hope I will meet you in Ireland 2009!
Last November I found the book from M. Simons about the Slingsby sailplanes in a book store in England - I was very happy to get it!

Can you please post some technical datas from your Dart. Especially what weight do you expect - and secondly if possible - what is the weight of your Skylark...?

Thanks a lot
Walter

cw · Posté le: 09/07/2008 21:59 Sujet du message:

Laurent, it took a lot of time to get the transmitter back from you...! Laughing

Walter, the new Dart will span around 5.6m and weigh 11-12kg
The wing section is HQ 35/15 at the root, tapering to 35/12 at the tip. There will be no wing twist or washout

The Skylark, at 1:3.5 scale weighs 8Kg and spans 5.2m

patte de loup · Posté le: 16/07/2008 22:19 Sujet du message:

Welcome on the forum Chris. Enjoy to read your new building . Very Happy

Nice to see you once again for Retroplane 2009. Wink

Pat'

cw · Posté le: 16/07/2008 22:46 Sujet du message:

Merci Pat...I hope you all had a good time at Retroplane 2008

Now, the 1st stages of the fuselage contruction...

Chris Ze Swiss · Posté le: 17/07/2008 21:58 Sujet du message:

Hello Chris!

I remember, last year, at the Rétroplane meeting, when I was helping pilots to carry their equipment from the car terminal until the slope, I came to you singing "If you want somebody, call my name", "remake" from Sting! Laughing

What a good time there!!!

Nice to meet you on this forum! Very Happy

Waooooo! Nice and fast construction!!! [clap]

Read you soon!, Christian

cw · Posté le: 19/07/2008 17:54 Sujet du message:

Hi Christian, nice to meet you again...!

Now we must build the wing centre section to work out how to best attach it to the fuselage...

cw · Posté le: 20/07/2008 20:40 Sujet du message:

Using a template to check the fidelity of the airfoil...

The rear of the ribs are reinforced with 0.75mm plywood

Now it is time to put fuselage and wing together

Laurent Beldame · Posté le: 20/07/2008 21:28 Sujet du message:

Good evening m'sieur Williams

One simple and innocent question:
The ribs of your wing seems to be mounted in a vertical way like the real thing I guess ; how can you ensure that there will be no twist at the end ?

I assume that the main factor depends directly from the quality of cutting of all pieces but .... [humm]

Merci

L

cw · Posté le: 20/07/2008 23:19 Sujet du message:

Laurent...it does not matter if the wing is twisted at this stage. It will twist easily if you apply pressure to it. Once the bottom sheeting is added it will only become rigid when the top sheeting is applied, then you will see what happens... Wink

cw · Posté le: 21/07/2008 22:18 Sujet du message:

Hah! I forgot to take the photos of the next stage Embarassed

So, here is the Skylark centre section, which is very similar...

As you can see, the wing rests on supports shaped to the bottom of the wing to keep it all straight...

Once the white glue has set, the wing will then be rigid

cw · Posté le: 23/07/2008 22:12 Sujet du message:

Back to the fuselage now...

The internal structure is braced with 6mm sq. balsa diagonals to prevent twisting during the sheeting process...

3mm sq. spruce reinforces the fuselage at the rear where the ply will have to be joined

The top .75mm plywood sheeting is soaked with water and heated with a domestic iron to take out some of the tension when it is glued to the fuselage...

12mm balsa sheet taped to the bottom longeron keeps the fuselage straight as the ply is glued in place...

Laurent Beldame · Posté le: 24/07/2008 13:24 Sujet du message:

Therefore we all assume that Mrs Williams (certainly an holy spouse!)knows where the iron is ... Laughing

L

loopingfred · Posté le: 24/07/2008 13:38 Sujet du message:

Well, she knows now that he can use it ! Laughing

cw · Posté le: 28/07/2008 20:16 Sujet du message:

Madame Williams knows where everything is...!

Moving to the front of the fuselage now:

The outer planking is covered with car body filler and sanded roughly to shape...

We have to start removing the temporary formers... (Note glassing in between the formers to hold the planking together)

Note the hole on the former to allow a finger to be inserted to pull it out!

Cleaning up with a power file..

Ready now to fully glass the interior...

patte de loup · Posté le: 28/07/2008 20:57 Sujet du message:

Hi Chris,

It can't be more clear Wink

Is the car body feeler named "Sinthofer ". Or what's it ? Polyester resin?
Soft? Easy to sand? [humm]

Pat'

Arnaudo · Posté le: 28/07/2008 21:24 Sujet du message:

Hello Chris,

Very pleased to see you on the forum. Having a look at your new building, reminds me the begining of the fuselage of the Minimoa. Building like ships.

Hope to see you one day, may be in ireland. If i succeed to build the Minimoa in lest than 4 years Very Happy

Arnaud

cw · Posté le: 28/07/2008 22:22 Sujet du message:

Pat, over here it is called this. It is easy to sand soon after it cures (5mins) but gets harder the longer you leave it...

Arnaud, it would be good to see your Minimoa in Ireland. 4 years is a long time, maybe this build log for my new Minimoa will help...?

http://www.rcgroups.com/forums/showthread.php?t=660340&highlight=minimoa

Arnaudo · Posté le: 29/07/2008 13:51 Sujet du message:

Chris,

I am building the 1/4 scale model i bought threw traplet. So this is your plan Very Happy

Started the log on retroplane.net on 02/2006

Arnaud

cw · Posté le: 01/08/2008 20:08 Sujet du message:

Keep building Arnaud...!

Now we must properly glass the inside of the fuselage (note card template)

A bit more filler on the outside to soothe the soul

Now to play with the retract...

Making the retract doors...2 pieces of 0.75mm plywood are laminated together with epoxy and taped to the bottom of the fuselage to get the correct shape...

cw · Posté le: 07/08/2008 22:26 Sujet du message:

Now the doors are fitted and held shut with torsion springs...

Time now to check on progress...

Starting on the wing/fuselage fairing...

More of the same...

GuillaumeG · Posté le: 08/08/2008 16:29 Sujet du message:

Hi Chris,
it's still nice and quick as usual! Your building is very efficient! I would like to ask you if you could make some close-up pictures of your retract system, and of the doors springs.
Keep going!
Thanks Wink

cw · Posté le: 08/08/2008 22:38 Sujet du message:

Gillaume, I should say that this build started earlier this year back in March and we are not up to the present date yet...!

The door hinging and springing I have copied from a Graupner Swift kit I built a few years ago. The doors have a brass tube epoxied to them and the retaining rods run through tubes in the fuselage so that they can be easily removed at any time. The torsion springs are just fine piano wire, also retained by small brass tubes as shown by the black arrows...

The retract is a standard Multiplex item...

GuillaumeG · Posté le: 09/08/2008 10:20 Sujet du message:

Thank you Chris that's clear (the same system is used in F3k for hinges of rudder for example).

Last question, how the doors remains "enough" opened, as it's the wheel going down which pushes them?

cw · Posté le: 09/08/2008 20:10 Sujet du message:

Gillaume, the doors rest against the retract legs: I have not yet worked out a method to make them open wider...

Meanwhile, before we can make the wing fairing over the centre of the wing, we must first make up the canopy frame to create the correct shape.

First, the starboard (right hand) rail must be hinged up...(Pressing the rail against the hinges marks the masking tape so that you know exactly where to drill the holes)

Now the rest of the frame can be made. The rear former is made up from laminations of .75mm plywood to obtain the correct shape...

The joints are reinforced with hardwood, to be trimmed up later

Drilling the holes for the locating peg to ensure that the canopy closes in the same place every time

Now the joints are reinforced with thin piano wire pegs...

cw · Posté le: 14/08/2008 21:49 Sujet du message:

Now that the canopy frame is assembled, we can start to make the wing/fuselage fairing...

1st, we make up blanks from 12mm balsa sheet

The balsa blanks are glued to a .75mm plywood base

The wood is sanded roughly to shape, and body filler is applied to get it all to the final smooth shape

et voila...

cw · Posté le: 17/08/2008 20:53 Sujet du message:

Now the outer wing panels must be made...

1st job: the wing joiner box (2 x 14mm flat brass boxes)

The wing box must be made while it is attached to the centre wing panel to ensure that the steel blades line up properly

Now we must make sure that the root rib lines up properly too

Once the bottom of the wing panel has been sheeted, it will be placed on these supports to keep it straight and true