Author Topic: Building a Slingsby Skylark 4  (Read 6662 times)

Ron

  • Guest
Building a Slingsby Skylark 4
« on: August 13, 2008, 10:25:13 AM »
This might be a bit long, so get your sandwiches and coffee ready :lol:
Only the names have been changed to protect the innocent, and prevent lawsuits :shock:

Building a Slingsby Skylark
From an ABC plan and a kit of ready-cut formers and ribs from XYZ Kits.

The story so far...

Started assenbling the fuz on the plan.
First observation is that the kit is different from the plan in the area of the front skid.
This means the cutouts on the front formers are wrong and the method of assembly will need drastic changes due to the thickness of the kit skid.

Talking by email to the designer reveals that he has never seen the ABC plan.
A bit gob-smacked by this.
And the ABC plan is different to his original, due, it seems, to 'corrections' made by ABC.
They were not corrections, the original was correct, they were in themselves introduced errors.

Talking by email to XYZ, the kit manufacturers, reveals that they transfer the original plans from the designer into a computer, using Autocad, so that the kit can be cut on a laser cutter machine.
They had queries at that time, but did not check with the designer, so again errors were introduced.
Gob-smacked once again.
Many parts were wrong in size and even shape.
Some were missing completely.

The plan from ABC is an old 'blueprint'.
This is produced by taking the original paper drawn plan from the designer, laying a sheet of matte transparent film over it, and tracing the drawing in ink.
This transparency is then used as the 'master' fo contact prints onto ultraviolet sensitive paper, and developed in a machine that uses rollers to expose the paper and put it through a developer bath.
This, in itself, introduces dimensional errors due to the master and paper running around rollers and 'creeping', and also the paper changes slightly with the developing 'damp' process and subsequent drying and folding.
In the old drawing office days this did not matter as the drawing had accurate dimensions written on the drawing itself, and the chap doing the job would use him own measurement tools to get correct sizes.

So...
Now we have a drawing that has been incorrectly 'corrected' and not checked by the designer, made in a system that changes the drawn sizes, and is being used as a template for the finished job.

And...
We have a kit of parts made from data about which there were doubts and was never checked.

Is it any surprise then that the two don't match up?

Additional comments:

1. There was information totally missing from the plans, like no mention at all that the tailplane was to be sheeted over with 1/16" balsa.
That only became apparent when the designer supplied a CD of photographs of his build, and subsequent emails to/from him.

2. There was no list of parts supplied in the kit.
This meant that there was no way to decide what other materials would be needed.

3. There was no materials list with the drawing.
This is against all my engineering training and experience.

4. There are even spelling errors on the plan, like 'apature' instead of aperture, and 'toy' instead of top.
This shows a lack of checking which is evident from previous remarks.


Conclusions so far.
Would I buy another kit from XYZ - NO.
Would I buy another plan from ABC - maybe, perhaps, but still consider blueprints to be old-hat.
Where the plan is to be used as a template it should be drawn on a modern plotter.

This is an ongoing saga, and the nice chap at XYZ has said he wants to sort things out.
I haven't talked to ABC yet.
The designer is obviously concerned.
I get the impression that I'm the first person to make this using ABC plans and XYZ kit.

To be continued.....

cvanscho

  • Guest
Building a Slingsby Skylark 4
« Reply #1 on: August 13, 2008, 10:56:41 AM »
Aargh!  Sounds like lotsa fun...not!

Imagine, though, when this glider is finally sailing gracefully through the sky, and you had to go though so much effort to get there!

Ron

  • Guest
Building a Slingsby Skylark 4
« Reply #2 on: August 13, 2008, 11:03:08 AM »
Ha :lol:

At this rate it might be sailing through the air fairly soon, and not all that gracefully :cry:

Fred

  • Slope Soaring is not a crime!
  • Administrator
  • Newbie
  • *****
  • Posts: 5121
  • Gliderist Simplex
    • View Profile
    • http://www.gliderireland.net
Building a Slingsby Skylark 4
« Reply #3 on: August 13, 2008, 11:09:46 AM »
:shock:
That's a bit of a pain !  :!:  :!:

Sorry to hear that Ron.

Now I hope the guys that cut the kit get the things right. I can understand a few mistakes (don't ask how I know  :mrgreen:   8-[ ) but having almost the entire kit wrong is bad. But I think the guys are serious and will find something.

Anyway, if we can be of any help, let us know !
Education is important, but flying RC planes and gliders is importanter!

Ron

  • Guest
Building a Slingsby Skylark 4
« Reply #4 on: August 13, 2008, 12:05:58 PM »
Thanks Fred.

I'm sure it will all come together.
It's the process that's the problem really.
Two separate routes from the designer to the plan publisher, and from the designer to the kit manufacturer.
And with 'corrections' being made on each route.

If the designer drew the original plan using Autocad or Turbocad and used that to make the first model, so he could make corrections, then all would be fine.
Then the kits could be cut direct from the computer files, and the plans could be printed on a plotter from the computer files.

But hey, this is a hobby right 8)
It's not really that important :lol:  :lol:

What am I saying :oops:  :oops:

Fred

  • Slope Soaring is not a crime!
  • Administrator
  • Newbie
  • *****
  • Posts: 5121
  • Gliderist Simplex
    • View Profile
    • http://www.gliderireland.net
Building a Slingsby Skylark 4
« Reply #5 on: August 13, 2008, 12:12:17 PM »
Leave this bottle alone Ron !  :P  :D

Yeah, I think if you design something to be made a SK from, you need to draw in CAO/DAO from the start...
Redraw a plan from a scan to make them compatible for cutting, is a big waste of time, might be better and less time consumming to restart from scratch and using computer tools...
Education is important, but flying RC planes and gliders is importanter!

Peter

  • ISR Club Member
  • Newbie
  • *
  • Posts: 185
    • View Profile
Building a Slingsby Skylark 4
« Reply #6 on: August 13, 2008, 21:11:02 PM »
That's a shame Ron that there are all those issues with the short kit and the plan.  I would have thought if one was going to market a short kit you would build or have someone else build a prototype first and iron out these sort of problems.   I actually have the Skylark plan too!  I was idly thinking of whether it would make a next project, but I decided on a Slingsby Gull 1 instead - but mustn't get ahead of myself.  I still have  some work to do on the Pilatus B4 although it is coming together now.

Ron

  • Guest
Building a Slingsby Skylark 4
« Reply #7 on: August 13, 2008, 21:33:43 PM »
Yeah it's the combination that's the problem really.
If I'd just used the plan alone there would have been a few questions, but the designer is very helpful.

And yes, even my wife's reaction was "It makes you wonder if anyone has actually built that kit before".
But it seems that the final plan and the final kit never come together for a check by anyone.

I've got another plan for a Skylark 1 - 107" span, and although that is a simpler construction there is more info on it.
Maybe I should have started with that  :?

We will overcome :!: