Purbeck 1/3rd Scale DG800 Build Thread

Let us all watch your new project progress.
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Geoff Pearce
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Re: Purbeck 1/3rd Scale DG800 Build Thread

Post by Geoff Pearce » 22 Mar 2018, 17:47

Simon WS wrote:
22 Mar 2018, 16:46
You know me Barry, spectator only at aerotow events!...

This one is just a tiddler Geoff, as I'm building it as the 5m version (for the slope obviously!).


Si
Nice project anyway, look forward to flying with you again

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terry white
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Re: Purbeck 1/3rd Scale DG800 Build Thread

Post by terry white » 22 Mar 2018, 20:26

Nice to see your off with start number two Simon.

You've certainly started with a bang, a lot done in one day ,look out Roo and Paul W. he will take the prize for first in the air if we let him. :lol:

As already mentioned all three models were prototypes. Each with a different lay-up and finish.The intention was to produce a model with a similar spec as the very popular ASW 27. The wing lay-up of your no2 kit has a full length, top and bottom spar with a carbon vertical section making it into an 'I' beam spar,The wing joiner is incorporated, and is an integral part of this spar.There are three 150g glass interweave cloths. The first covering in an elliptical manner the wing joiner block and front and rear incidence blocks,the weave placed diagonally to the span. The second leaf was taken from the root to beyond the air break position with the weave span wise. the third and final leaf was taken from root to the whole length and cord of the wing.Carbon tows were layed into the trailing edge for stiffeners and to allow sanding to a sharp edge without the edge wandering from the straight. The spoiler channel was fitted, the low voltage drop cables to the 5in No servo positions in each half span. Last but not least the full length hing line was fitted with peel ply to make the living hinge which you have mentioned. All was then uncased into 1.2mm obechi veneer epoxy bonded, into the vac bag and low temp oven overnight and one day.
The following few days, while on test it showed that due to the long half span and short cord,coupled with a reasonable thin but changing section, the wing did show more flexibility then we wanted,so the following two prototypes were layed-up the same but changed the third full length interleave of glass to one of carbon cloth. This certainly made the wing much stiffer as you noticed with your first kit.
However a hand built wing of this complexity was becoming overly expensive to produce for mass production, hence only the three were ever made.

Don't think that the flexibility of the wing will lessen its strength in any way,That wing is incredibly strong where it is required to be.In the past I often gave talks to surrounding clubs on club nights. Any who were in attendance will tell you that for the party finish I would span a wing across the back two chairs at the tip and the root and then stand a medium size car battery in the middle of the wing, leaving it there while I took question and answers,just to show how strong Purbeck wings were, :o Can anyone out there remember this?

Well done Simon, I'm here if need me. Terry (Purbeck sailplanes)

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Simon WS
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Re: Purbeck 1/3rd Scale DG800 Build Thread

Post by Simon WS » 23 Mar 2018, 06:16

Thanks Terry - great to have that info. I'll try to limit the number of stupid questions I ask!
The added glass and Kevlar in the fuselage has made a huge difference to the stiffness so now I'll start adding ply bulkhead corners to add crush resistance around the wing joiner and incidence pins.

I'm actually enjoying it again!

Simon

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terry white
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Re: Purbeck 1/3rd Scale DG800 Build Thread

Post by terry white » 23 Mar 2018, 10:44

Si,If getting you to enjoy your modelling again is all that the DG 800 achieves, it will be well worth while. Ter.

catwok
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Re: Purbeck 1/3rd Scale DG800 Build Thread

Post by catwok » 23 Mar 2018, 20:12

Glad to hear you have found your bag of "mojos" Simon....

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Barry_Cole
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Re: Purbeck 1/3rd Scale DG800 Build Thread

Post by Barry_Cole » 23 Mar 2018, 23:34

But he is still looking for his tow release.....

:shock: :shock: :shock: :shock:

BC

Geoff Pearce
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Re: Purbeck 1/3rd Scale DG800 Build Thread

Post by Geoff Pearce » 24 Mar 2018, 15:31

Barry_Cole wrote:
23 Mar 2018, 23:34
But he is still looking for his tow release.....

:shock: :shock: :shock: :shock:

BC
He's got enough friends who could lend him one no excuses :cry:

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Simon WS
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Re: Purbeck 1/3rd Scale DG800 Build Thread

Post by Simon WS » 26 Mar 2018, 16:07

I've been hard at it since I got the second DG and with huge thanks to Paul and Terry for help and advice the ailerons and flaps are roughly cut out from the wings leaving the live peel ply hinges intact. They still need a bit more work to free them up and get clean edges, but Terry assures me it is actually quite difficult to wear your way through the peel ply so I am gently using a triangular file to ease them up a bit!

Image

Already getting a decent range of movement.

Image

Next I drilled the joiner hole in the fuselage wing roots and trial fitted the wings and checked alignment with a laser and via the traditional measuring between wing tips and fin (I confess I had to Photoshop this image because the actual laser lines weren't too visible in the photo, but it did work well in practice - honest!)

Image

As this is a hand built prototype, a few adjustments were necessary to the joiner tube alignment to get the wings square to the fuselage and I will need to do some fairly major surgery to the wing roots to get a good fit.

Image

Anyway, I'll tackle that when I've made all the crush bulkheads and glued them in. I fancied a bit of bling (and strength) so I laminated some ply sheets with 200 gm carbon each side and then started marking and then cutting them out. I don't know if others have a better way, but I use bits of cardboard and basically use an iterative process to get a good fit. I ended up with quite a lot of them!

Image

Image

I don't know if any of you are Scrabble Players or Countdown Watchers but I'm sure you can do better than my "Doc Driving Under the Influence"!

Then a quick fit into the fuselage and that's enough for today.

Image

I realise I'm not doing anything that others have done many times so maybe these postings aren't of any interest, but TBH it helps me keep at it, so plan to continue unless asked to stop!

Simon

john greenfield
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Re: Purbeck 1/3rd Scale DG800 Build Thread

Post by john greenfield » 27 Mar 2018, 08:50

Don't stop !!!

AEB
AEB = Aeronautical Energiser Bunny (with thanks to CW)

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Barry_Cole
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Re: Purbeck 1/3rd Scale DG800 Build Thread

Post by Barry_Cole » 27 Mar 2018, 09:15

john greenfield wrote:
27 Mar 2018, 08:50
Don't stop !!!

AEB
Until the Ailerons fall off??????

:shock: :shock: :shock: :shock:

BC

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