Phil's Barnstormer

[Phil Winks]

Well not to much any way Kevin , I have got about a dozen or so brackets to make for the jig, not an appealing little job but it will make future wings so much easier so I guess it has to be done

[Phil Winks]

I've finally got the main wing under way. 1st I set up a jig which consists simply of a piece of 18mm MDF long enough to take half the wing and enough for the 4 centre section ribs past the tip. this is marked with a series of parallel lines to denote one edge of each rib at the required spacing. perpendicular to these the 2 spar positions and the leading edge are marked, all done with a fine pencil and a true square as accurately as physically possible. either side of each rib position away from the spars (between them in fact) a series of pilot holes are drilled for the right angle brackets that will be used to hold the ribs in position and true, then a 20mm ali angle is fixed to the Leading edge mark to but the front of the ribs against. this allows the wing main panel to be dry fitted to check all is well. when happy the ribs can be glued to the bottom 2 spars with the angle brackets clamped either side of them to hold firm, then the top front spar is glued in and weights applied to the top of the wing till dry.

and a closer view showing the angle brackets in position

once this is dry I add the shear web, this has been, as many have, moved to the front of the main spar, in my case to accommodate the wing tube behind and touching it,

the observant will notice a double rib at position 4, this is where the plug in outer panel will be separated once this panel is ready for covering. Also you should note I've removed the section for the ailerons and flaps carefully retaining the rib of cuts to make the ailerons and flaps with later. the piece of angle ali in this area is to facilitate the clamping of the new trailing edge to ensure it is perfectly straight.

I should also add the inner most rib has been set at a minimul 1 degree inward from vertical, for the dihedral this angle was set by cutting that edge of the shear web and fixing the 1st rib only as I fitted that piece of shear web.

Edited By Phil Winks on 08/03/2014 16:50:54

[kevin b]

Hi Phil.

Fitting a tube between the spars. Will it strengthen, or weaken the ribs ? I'm pretty sure with the extra bonding area that it will strengthen it, but if it weakens the structure, wouldn't you be better leaving the webbing where it is ?

kevinb.

[Phil Winks]

Hi kevin to give you a better perspective on the placing of the wing tube

click on the pic for a larger image.

As you can see there is still substantial material above and below the tube and being epoxied to the shear web at its contact point will add imense strength. the plan is to use a tube of self mixing epoxy ( comes in a double syringe with a mixing nozzle) to lay a fillet of epoxy above and below the tube between it and the web.

[kevin b]

Thanks Phil.

I think in the scheme of things the tube must add strength (as well as weight) to the structure.

kevinb.

[Phil Winks]

Certainly it does both but at an estimated 1/2 to 3/4 oz per tube the weight gain is minimul and its bang on the COG so affects the balance not one jot, the important function is it allows me to get a 5' 3" wing into a much smaller space for storage and transport

[Phil Winks]

progress report the wings are going slower than expected partially due to a day at the field sunday but given the glorious weather it just had to be done

once the ribs and spar joints were dry I lifted the wing up in the jig and fitted the lower leading edge sheet using the recomended 3/8" packing pieces under the front as in the 1st picture, the trailing edge sheet is placed dry underneathe to keep the ribs flat when weighted down.

then, remembering to wrap those LE packing pieces in packing tape to prevent them becoming a permanant fixture, the 1/2" x 1" LE block was glued in using mini sash cramps from the LE to the spar to ensure a firm clamp against the LE of the rids while the aliphatic dried, this was followed by the lower TE sheet being glued and the ribs weighted again while it set. Once the weights came of this is what we have.

so next is to trim the excess from each end, except the upper main spar, and the reason for this I'll explain when I've got the other wing to this stage. Note the LE sheet goes back to the rear edge of the main spar and the TE sheet while supposed to be 1 1/2" has been taken to the 3/16" sub spar put in to carry the aileron/flap hinges 2" from the TE, the TE sheet has been purposly left long untill the top sheet is run down to it to ensure a good clean joint between the two.

PS thats a total of 118 photo's in the album for this most pics I've ever done for a build my ISP will be complaining about my band width usage 

Edited By Phil Winks on 11/03/2014 21:50:42

[Biggles' Elder Brother - Moderator]

Coming along very nicely Phil.

The problem now of course is that you start to run into the flying season and it becomes a dilemma "do I stay at home and build, or do I fly and my schedule slips back" - but its nice when the weather lets you have the option!

BEB

[Phil Winks]

Posted by Biggles' Elder Brother - Moderator on 12/03/2014 00:35:07:

Coming along very nicely Phil.

The problem now of course is that you start to run into the flying season and it becomes a dilemma "do I stay at home and build, or do I fly and my schedule slips back" - but its nice when the weather lets you have the option!

BEB

Thanks dave well your right of course but given my aim for the 1st part of this flying season ( my A test) the flying will get priority at least once a weekend leaving me a day and evenings to try and keep this on schedule, to be fair it is on the home straight, well nearly only the windscreen on the fuse and this wing to complete.

[Phil Winks]

Just to keep up to date I haven't been idle during the week, and despite skiving of to the airfield on Thurs afternoon now have two half completed wing panels, both at the same state with the leading edge and bottom sheeting fixed, if you look closely, which you cant cos I forgot to take the pictures, I've fitted the hard points for the cabane fixing points.

A point has come to light regarding these, future builders may want to spread rib 4 further out as, if the fixing holes are drilled dead centre of the flat section at the top of the cabanes, thankfully mine aren't drilled yet, they come very close to the inboard side of rib 4 and may make fitting the T nuts difficult.

What did I say earlier about thinking ahead

[Phil Winks]

A quick update here 1st the missing photo from the last post, ie: the cabane hard points

When fitting the wing the front hard point will need some resin injecting into the gap between the lower sheeting and the ply to prevent crushing

Next the servo try mounts and servo tray blanks

Also visible are the flap/aileron riblets and LE glued to the TE bottom sheet, the T pins are to create the gap required for the hinge, thick CA was used here with a kicker spray to simplify this fiddly job.

next I've profiled the aileron/flap LE and the trailing edge of the bottom sheeting

and fitted the trailing edge top sheet after marking the cut lines on the bottom sheet ready for separating the ailerons and flaps once the aliphatic dries

[Tony Bennett]

looking good sir.

be flying soon then.

[Phil Winks]

thankyou sir About 3 weeks I reckon Tony, still quite a bit to do and as you can see the down side of a small workshop is only one job can be tackled at a time, so while this wing is drying the other has to wait.

Left to do: get the second wing to this state with the ailerons and top sheet, then produce the bespoke ali bar dihedral brace/centre section joiner, this will effectively make the two wing tubes become one when they're inserted into the centre section, more details as I go on, then I need to make and fit both wing tips, finish the servo trays, join the centre section halves, fit the T nuts into the hard points, fit the outer panel retaining bolts then cover.

[Phil Winks]

A little more progress this morning,

The second wing has caught up with the 1st and the centre sections have been split from their respective outer panels.

I've addressed the wing tips with a mod I alluded to earlier, basically I've given her a trainer style tip with the top of the tip flush to the top of the wing and I've raised the back of the tip section by 1/8" to give the tip only a tiny bit of wash out.

Lightening holes still need to be cut and the fillets shaped but this is where the tips are at present.

The glue you see foaming out of the joint is light weight gorilla glue ( a foaming polyurethane glue) this stuff is immensely strong and pretty fast to go of too, this is the white stuff not the stronger and slower setting brown variety they make I may well be tempted to use that at the centre join instead of epoxy.

Now the issue with the width of the cabanes / hard points as detailed on the plan, as you see from the pic below a 25mm packer is needed to get the hard points any where near the centre of the top of the cabanes,

I'm not sure how this has come about but will be checking the wings against the plan etc to work it out

[Mike Hardy]

Hi Phil, I thought I would wait until you finish before I make a start!! Seems a complex build? but your build blog will help a lot.

Question - your wood list, does it need modifying in light of your experience so far?

Your progress seems pretty impressive so far.

Mike.

[Phil Winks]

Hi Mike and thanks. I did need to get some extra 1/8 and 1/16th sheet but that was probably due to it being used on another build. One point i would make on the plug in wing mod is the tube joiner, ideally it need one to have access to a small lathe and fairly accurate bending facilities for a 10mm die Ali bar approx 5" long. More details will follow soon as I intend to make it this week.

[Mike Hardy]

Hi Phil, Yes I heard you had a new 'play thing' for Christmas!! Have you thought about making up a wing joining kit for the project now you have the kit to make? I am sure all of us would be interested in purchasing such from you. I think you are using phenolic tube in the wing panel - where did you get this from? or could it form part of the 'kit' Once the wing panels are 'plugged in' so-to-speak how do you propose to prevent them coming apart during flight?

Regards, Mike.

[Phil Winks]

Well it was a little after Xmas and was courtesy of my tax rebate god bless the HMRC

The phenolic and ali wing tubes came from Fighter aces and are pretty good quality, though my two came from differing batches as there wasn't enough stock when I 1st ordered and there is a minimal difference in size the tube from one will not quite fit the other about 4 thou difference which on a close sliding fit can make a the difference between a smooth and a tight fit. So if I was to make up wing tube joiners for any one, which I will do if asked, I'd need the off cuts of tube and phenolic, about 20mm would be fine as the fit needs to be as close as possible with out being an interference fit.

Edit to answer your last question Mike

There will be 2 ply tabs that protrude from the wing panel that coincide with slots in the centre section and pass into a hardwood block glued to the inner edge of R4 (last outboard rib on the centre section) then a 3 or 4mm bolt will pass down through the tabs and the block into a T nut in the bottom surface of the centre section, not being a wildly acrobatic model the forces pulling the wings outward are minimal so very little is needed to hold them in place and its pretty amazing what the shear strength of a 3mm bolt is. this one in a wildly out of control mega spin probably won't make them fail

Edited By Phil Winks on 24/03/2014 18:24:56

[Tony Bennett]

still a good looking build sir. yours will fly before mine i expect.

[Phil Winks]

thankyou Tony, hopefully it will live up to expectations.

Now with one wing panel close to completion (just a few rib caps and the retaining tabs to fit) I thought I'd show my modification to the wing tip, basically I've treated it to the trainer wing treatment which could arguably help with any tip stall tendancies, my own personal night mare,

And just because I can 2 general views of the panel, seems a shame to cover it

[Devcon1]

Phil

You could always go transparent on the covering. I like the wing joining setup.

John

[Phil Winks]

Posted by John Milne on 24/03/2014 19:04:13:

Phil

You could always go transparent on the covering. I like the wing joining setup.

John

This is sad but as a joiner that option is very tempting John

[Phil Winks]

well after several evenings in the shed and a good part of this afternoon bent over the lathe I'm now read to complete the wing construction by joining the two halves of the centre section.

1st the servo trays have been completed and a 1/2" strip of the centre section top sheet fitted behind the L/E, to allow the L/E to be profiled,

Below you can also see the fixed tab in the outer panel for the top retaining bolt to pass through

on the centre section the block holding the T nut for the retaining bolt is visible inside the box that is simply there to help, along with the sheeting, spread any loads across two ribs

the wing tube joiner rod in all its splendour

then the tube joiner in situ with half of the centre section removed

and the whole ensemble ready for glueing/screwing together, I've trial fitted this all and am delighted with how rigid the centre join is even without the essential epoxy or those clamps in the next picture,

finally when this is all covered I will have a metal strip joiner approx 40mm long screwed across the outer panel/centre sect join into the L/E as a final belt and brace so to speak, there will be a spruce strip let into, and profiled to, the L/E at this point to take the screws

So next up will be to get that centre epoxy joint done, 1st thing tomorrow, then I can trial fit this all to get the T nuts located for the cabane fixing points before progressing with the centre top sheet and getting the whole thing ready for the covering. Also a servo ext lead needs fitting from the aileron servo bay to the wing root.

[Phil Winks]

centre section all glued up so will be progressing this during the week hopefully

[Phil Winks]

Here we go pretty much on the home straight, my most feared section of any build, getting the wings on straight and square. To be honest I never know when its over why I worry, if accuracy has been the watch word throughout the build, then little can go wrong and any slight discrepancies are easily fixed in most cases, this one has come out within 0.5 mm measured from wing tip to top centre and bottom front of the tail fin on both sides, taking 4 measurements, 2 either side always makes me more confident of the results and helps prove the tail fin is vertical too, All that said any minor alignment issue can be got round by drilling, in this case 3 out of 4 of the cabanes out by 0.5 to 1mm more than the bolt so the wing can be rotated slightly before nipping the bolts up tight.

so now the pics

Phillipe (Well everyone else has named their pilots and the french theme seems to fit) looks like he's wondering when he will eventually get his wings

The metal bolts will swapped out for nylon ones.

The cutout above the pilot looks a little to far back to me but I dare not cut through the rear spar.

Edited By Phil Winks on 31/03/2014 21:08:34