SZD30 Pirat

Let us all watch your new project progress.
Richard Farrer
Posts: 18
Joined: 07 Oct 2015, 21:32
Location: Whiteshill, Stroud

SZD30 Pirat

Post by Richard Farrer » 23 Dec 2017, 16:45

Well I promised you a build thread and now that some significant progress has been made here it is. First photo is of the assembled parts then a photo of the fuselage ready for planking with the jig in the background and the half finished tailplane in the foreground. Before planking I am preparing the radio installation, fixing the tow release in position and epoxying in a precautionary 500g of lead.
Attachments
2017 Nov Pirat  parts 2.jpg
2017 Dec 1.JPG

Nigel Argall
Posts: 122
Joined: 20 Mar 2015, 18:26
Location: Cornwall

Re: SZD30 Pirat

Post by Nigel Argall » 23 Dec 2017, 17:03

Is the jig in the background for the Pirat or something else? Also, how come everyone else has such incredibly clean and tidy workshops??!

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manolo
Posts: 17
Joined: 18 Mar 2015, 10:08
Location: VALENCIA (SPAIN)

Re: SZD30 Pirat

Post by manolo » 23 Dec 2017, 18:01

They clean them and order them just to make the photo ... :mrgreen:

Richard Farrer
Posts: 18
Joined: 07 Oct 2015, 21:32
Location: Whiteshill, Stroud

Re: SZD30 Pirat

Post by Richard Farrer » 20 Jan 2018, 16:29

Nearly a month has gone by and the winter weather has kept me in the man cave. This is my first quarter scale build and I am staggered by the number of hours I have put in to get this far. The fuz is planked up and ready for its glass epoxy covering. I finished the tail feathers and when I received the natural Solartex I just had to cover them to see what it would look like. I have also built one outer wing panel. That was difficult as the plan seriously lacks detail in the aileron department. The accompanying magazine article is of little help as it emphasizes applying scale details rather than how to build the thing. The wing tips were finally made by laminating soft balsa either side of a ply core. The result is pictured.
There will be a long gap before the next post as I am off to find some Portuguese sunshine in my motorhome accompanied by a brace of slope soarers. Its a hard life being retired!
2018 Jan 006.jpg
2018 Jan 004.jpg
Attachments
2018 Jan 008.jpg

Richard Farrer
Posts: 18
Joined: 07 Oct 2015, 21:32
Location: Whiteshill, Stroud

Re: SZD30 Pirat

Post by Richard Farrer » 06 Feb 2019, 22:36

I see that over a year has elapsed since I posted a progress report. Although the build continues I keep being diverted to build other models. I had to wait until the weather warmed up to glass the fuselage but that has now been done and it is painted. I have built the second tip section and started on the wing centre section which is a couple of centimetres shy of two metres long. It is a huge plank being of parallel chord. A lot of soul searching has gone into the construction of the centre section to ensure that it has adequate strength. My previous Pirat, bought secondhand, suffered wing failure across the airbrake cut out so I didn't want that to happen again!
I consider myself to be an experienced builder but I have found this build very taxing and I would not encourage anyone else to build from this plan as it is inaccurate and lacks important detail. The wing joiner detail in particular is misleading and has caused the burning of much midnight oil.
I can see the end in sight however and am hopeful that a maiden flight will take place this summer.
Attachments
2019-02-02 11.10.28.jpg
2019-02-02 11.29.08.jpg

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B Sharp
Posts: 642
Joined: 19 Mar 2015, 17:18
Location: Perthshire

Re: SZD30 Pirat

Post by B Sharp » 07 Feb 2019, 09:23

That is coming along very nicely Richard.
Many years ago I purchased a similar Pirat on Ebay. When I picked it up the fuselage was a glass moulding in poor condition and all the flying surfaces were effectively scrap. I purchased the plans that you have and constructed the wings tail and rudder from them. I wholeheartedly agree with your comments as I had to do a lot of mods before I was happy with the results.
Although it looked ok the tailplane incidence was wrong resulting in a near loop on the first launch. (It may be worth your while to check this on your model - 1.5 degrees should be about right) I accept that this was my fault and I inserted a fair chunk of packing. Having said all this the Pirat flew very well and gave me a lot of pleasure for many years.
Brian. :)

Richard Farrer
Posts: 18
Joined: 07 Oct 2015, 21:32
Location: Whiteshill, Stroud

Re: SZD30 Pirat

Post by Richard Farrer » 12 Feb 2019, 21:04

Hi Brian, Thanks for that info. I will check the incidence thoroughly. As you will recall the wing section is thick and undercambered. When setting the incidence what would you consider to be the zero incidence line for this aerofoil? The tailplane is symmetrical so no difficulty there.
I have now finished sheeting the centre section after much concern over the strength of the resulting structure. Now to construct a wing fixing system that doesn't rely on clamping together two alloy plates with sandpaper glued to them! Some M6 Stainless steel bolts straight through the wing into a big juicy ply/balsa cross member in the fuselage will suffice, I think. Cheers Richard

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chris williams
Posts: 1011
Joined: 10 Mar 2015, 10:50
Location: Blandford Dorset

Re: SZD30 Pirat

Post by chris williams » 12 Feb 2019, 21:33

Richard, what scale is the model? I ask because rigidly fixed wings on the top of a fuselage can be very susceptible to the loads experienced in a cross wind landing...

Nigel Argall
Posts: 122
Joined: 20 Mar 2015, 18:26
Location: Cornwall

Re: SZD30 Pirat

Post by Nigel Argall » 14 Feb 2019, 09:58

Chris, I’d love you to say a bit more on this. Pretty much every power model I have ever owned (and a good few of the smaller gliders) has had some variation on the dowel-at-the-front-and-plastic-bolt-at-the-back type of fixing. Why is this not suitable for larger models? Is it the structural strength or simply that you are looking for a bit of ‘give’? (Maybe a lot of give?). I have noticed on your videos that there is often a lot of movement at the wing root – i.e. the gap opens up as the model loops. In other words is the practice of holding wings on with shock cord as important as the type of mounting?? Hope all this makes sense.

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chris williams
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Joined: 10 Mar 2015, 10:50
Location: Blandford Dorset

Re: SZD30 Pirat

Post by chris williams » 14 Feb 2019, 11:46

Nigel, it all depends on how and where you intend to fly...If you are going to fly solely from aerotow, then you will presumably always be landing on a nice, smooth surface. If you are going sloping, then the chances of a hard landing are that much greater. For a model, say, 10lbs or under, you should be able to get away with using a couple of plastic bolts as the main wing retention method. Anything heavier and you might have to go to at least one metal bolt, with an ali bracket , both in the wing and in the fuselage. The huge advantage of shoulder-mounted wing with rubber band retention, is that the the rubber absorbs nearly all the forces when things go divergent on you.
Another method for a top-mounted wing is to make up a wing joiner box, bolt it to the fuselage, retain the wings with rubber bands, and hide the whole shebang with a detachable fairing. (A la Topaze) That only works for a two piece wing setup, though...

The bottom line is: 3-piece wings suck!

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