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A4 Skyhawk - Building tips and Plan queries


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The following 2 minor issues effect Sheet 2 of the current A-4 Skyhawk drawing.

Firstly, it has been brought to my attention that the composite Rib 1 section drawing shows the aileron stock dimensioned incorrectly (Red circle below) - It SHOULD read 1.5" x 5/16" (as per the Green circle)

section issue 1.jpgNote the plan view of the wing on this same sheet correctly shows the aileron stock as 1.5" x 5/16".

section issue 1 fixed.jpg

Secondly, it has been suggested that the extent of both the top and bottom 1/16" wing skins could be misinterpreted by the builder, leaving them shorter on chord than required. The plan is currently drawn like this, the sheeting lines are shown to identify the varying direction of grain on the top and bottom skins.

skin issue 2a.jpgThe Red circles show the issue - this could be read such the skins run UPTO the Sub T/E and Sub L/E - but cutting the skins to this line will leave them a little short. Of course in reality the Sub T/E and L/E are glued ONTO the bottom skin, the top skin flowing over the rib profiles and onto them both when fitted later.

The drawing should be altered like this, making it clearer (Green Circles) that the skins overlap the sub T/E and L/E stock. Of course in reality, the skins should be left with ample overhang anyway to allow for any curvature along the ribs length - the top and bottom skins are then dressed back to the sub T/E and sub L/E before the true L/E and T/E sections are fitted.

skin issue 2a fixed.jpgI've contacted Traplet on both of these minor amendments in the hope that any future sales of the plan will receive the updated drawing.

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I've been made aware of a missing component in the Traplet woodpack today by a modeller who received his package this week and has spent some time checking the parts against the plan. A reported missing fuselage former F2!

Anyway I double checked my parts and mine is the same, I contacted Matt Jones and his pack too contains no former F2.

It must have been missed in the laser cutting programme, so Im assuming all packs manufactured and distributed so far will be the same.

It effects Sheet 3A, 3/16" balsa, below is the pdf from the laser programme showing clearly F2 in position.

sheet 3a.jpg

And heres my woodpack. You can see where the part ID F2 has been etched correctly, but the part not cut.

missing f2 sheet 3a.jpg

Of course the former is drawn to scale on the plan, so making the former will be easy enough, the material IS of course on Sheet 3A so its best cut from there as the grain is correctly orientated for use.

I have contacted Traplet today and I'm sure the laser programme will be corrected first thing tomorrow, apologies to those who have already ordered and have woodpacks effected in this minor way.

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I've spoken with Traplet on the missing F2 issue and they have confirmed there was an issue with the laser programme on Sheet 3A. This has now been resolved so all A-4 woodpacks manufactured from today will include the laser cut F2 as originally intended.

Although it is a simple enough task to trace the shape of F2 from the plan onto the wood to create your own former, utilising the 'spare' material on Sheet 3A, Traplet have kindly offered to supply anyone who has already purchased a woodpack with a laser cut F2. If you would like to obtain one please contact their Customer Services department by mail at customerservices@traplet.com or by phone - Tel: 01684 588599 quoting your address. There will be no charge.

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Hi Phil. Just got my plan and wood-pack today.smiley.

I have been studying the plan in anticipation, and I have a question - well more of a comment. If I'm reading it right, the plan seems to show no clearance between the aileron torque rods and F6. So presumably we need to be very careful with the upright length on our torque rods? Or maybe we could move the wing bolt a bit further aft and reduce the size of F6, to create more clearance, and put a bit more reinforcing on the wing trailing edge?

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Flyer - Yes I think you may have to redraw former F2 to a slightly different shape if you are going with a 2 seater variant... I must admit I've not studied it too hard but I think it will vary slightly.

Steve/Mark - this is a good spot! The clearance here was a bit of a compromise in an attempt to minimise wing bolt length to something reasonable, and Mark you are right, the composite section shows the torque rods with a better vertical length, avoiding the clash that appears apparent in the main fuselage profile, below.

torque rod clearance.jpg

In reality, there is no need to make them even that long. Aware of the possible clash, we cut the vertical rods down to just 18mm on the prototype, and this has worked without any risk of clash, plenty of room!

torque rods.jpg

wing bolt.jpg

Good discussion, and worthy of note to any builder - Aileron Torque Rod vertical height no more than 20mm

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Just thought I would quote from someone who has been banned from the Leek and Moorland Club "PSS is for people who can't fly!". Obvious why he is no longer a member? Then I started wondering? Only Batman and Superman can fly.

My pack has arrived - also my Balsa Cabin woodpack but they are still unwrapped. I will be too tempted to open them.

Sorry - a bit off subject.

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Hi Phil,

I must compliment Blackburn Model Supplies on their excellent customer service. On Sunday14th Feb I placed my order for the Skywhawk additional parts. On Monday they phoned me to say the specified snakes were unavailable, would another type do? I said yes, and on Tuesday the pack arrived on my doorstep in Dumfries, 130 miles up the road. 10/10 guys!

The woodpack arrived on Wednesday, complete with F2 on a separate bit of balsa, I can't wait to get started.

smiley

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Hi All,

Have you got more details of how you made the canpoy plug Phil ? I've a vague idea, from magazines etc, but it would be useful to me (and the others doing the two seater), to see how to make a viable plug. Is it bascially blue foam, covered in body filler etc?

I actually have a client who moulds motor cycle screens, so I am certain that if I give him a decent plug, he;ll be able to vac form it for me.

I've done a quick searchg on here about making canpoy plugs, but have drawn a blank.

Cheers

Ade

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Thanks Phil,

I'll do likewise then. Although I'm thinking opf smooth canpoy and making actual scale frame to go over it? Never done anything like this before, so it's a steep learning curve.

I'll make sure I document it on my build blog, least I'll give you lot something to laugh about secret

Cheers

Ade

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