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1/4 Scale ASK21

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Mike Forsyth
Posts: 26
Joined: 14 Jun 2015, 09:30

Re: 1/4 Scale ASK21

Post by Mike Forsyth »

Hi Peter, I have been watching this build and was wondering what weight of cloth you used in your epoxy glass fuselage, and how many layers? and did you use a gel coat or was this just layed up just using epoxy as the first layer?

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Peter Balcombe
Posts: 1250
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: 1/4 Scale ASK21

Post by Peter Balcombe »

Hi Mike,
I used an epoxy compatible polyester gel coat (Easy Composites GC50), then a 100gsm layer from nose to wing root, plus 2 layers of 300gsm (one twill? & one plain weave) using 5 main pattern shapes per side.
In addition, I used 300gsm blisters in the wing root, main wheel & tailwheel fairings, plus strips/rovings around all of the canopy flanges.
The layup was as recommended by John Hall who has made all the fuselages for the Pat Teakle range over the years.
1/4” ply wing roots have now been epoxied into the insides of the wing roots & glassed over.

My only issues were where the mould surface wasn’t perfect (primarily around the wing root/canopy flanges) & my layup also had a couple of voids behind the gel coat in similar areas.
However, as I didn’t have a pigment in the gel coat (GC50 is clear only) then it isn’t really a problem as I have to paint the part in any case, so this will also cover the small amount of filling needed.
Peter

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Mike Forsyth
Posts: 26
Joined: 14 Jun 2015, 09:30

Re: 1/4 Scale ASK21

Post by Mike Forsyth »

Thanks for the information, it will come in very handy. One last question what was the weight of the fuselage? I always wanted to try making a glass fibre fuselage, but I think I will try on a smaller model first, just to test the water so too speak, I don't think I'm brave enough to do a 1/4 scale model, Even though you have a few imperfections you have done a remarkable job on your very first glass fibre fuselage I can only hope I'm that lucky.

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Peter Balcombe
Posts: 1250
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: 1/4 Scale ASK21

Post by Peter Balcombe »

Mike,
Bare fuselage weight with ply root blanks fitted is 1.7Kg for a fairly bulbous 2m long fuselage. (Wing is 70mm thick at root).
Not sure if this is heavy or not, although I gather that epoxy resin fuselages are usually lighter than polyester resin ones, but this obviously depends on the quantity of cloth & resin used in each case.

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Simon WS
Posts: 282
Joined: 18 Mar 2015, 11:39
Location: Kent, UK

Re: 1/4 Scale ASK21

Post by Simon WS »

Fantastic achievement Peter.

Simon

Geoff Pearce
Posts: 425
Joined: 18 Mar 2015, 09:11
Location: SN11 9EE

Re: 1/4 Scale ASK21

Post by Geoff Pearce »

Well done Peter, will you be challenging Roo for fastest build? :lol:

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Mike Forsyth
Posts: 26
Joined: 14 Jun 2015, 09:30

Re: 1/4 Scale ASK21

Post by Mike Forsyth »

Thanks, Peter. 1.7kg for the fuselage is not too bad, I will be watching this with special interest. You have done a Fantastic job 😃

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Peter Balcombe
Posts: 1250
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: 1/4 Scale ASK21

Post by Peter Balcombe »

Geoff,
I don’t think Roo has anything to worry about 🙂
It’s taken 18 months so far to just get a fuselage.
However, wing & tail designs are done, so maybe have something to maiden by next Spring.

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Peter Balcombe
Posts: 1250
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: 1/4 Scale ASK21

Post by Peter Balcombe »

With fuselage available, I have designed a tailplane arrangement using DevWing, transferring the output to DevCad to work up the detailed cutting templates and annotated build plan.
Cliff Evans kindly cut some parts for me, so the tailplane has started taking shape as shown below.
The plan is to embed a thin wing servo in the rear of the tailplane, this driving the elevator via a short pushrod to a ball joint on the bottom of the central elevator half joiner. The linkage sits in a slot cut in the top of the fin.
The tailplane is attached using a single bolt and anti rotation pin.
Tailplane internals
Tailplane internals
Last edited by Anonymous on 14 Sep 2018, 09:01, edited 1 time in total.
Reason: Problem with picture.

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Simon WS
Posts: 282
Joined: 18 Mar 2015, 11:39
Location: Kent, UK

Re: 1/4 Scale ASK21

Post by Simon WS »

Looks very neat Peter
Simon

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