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Flair Fokker D.VII Build

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Scott Edwards 202/09/2013 08:25:53
197 forum posts
96 photos

Holy Bellcranks Batman !! Golly, must have been designed when servos only came in one size. I suspect bellcranks will be a lost art soon. Watching with interest, and looking forward to seeing those Lozenges (rather you than me though mate ...)

Andy Blackburn02/09/2013 16:21:59
510 forum posts
487 photos
1 articles

I think bellcranks are Ok as long as ball-links are used everywhere

> ...looking forward to seeing those Lozenges (rather you than me though mate ...)

I'm still looking for ways to cheat with the painting, but I suspect that it'll come down to using paint masks and tidying-up the edges by hand afterwards - long way off that yet, though.

Anyway, after a bit of a medical-induced hiatus (and a failed experiment to see if it was possible to flatten the sheets of liteply that contains the ribs), I'm getting back on track. This is where it's got to as of about 4 pm today:

top-wing-1.jpg

Having built the bottom wing, the top wing is probably a bit more straightforward; bottom LE, TE & capstrips, then spars, then ribs & webbing, then top LE/TE/capstrips. It'd probably be easier with thin cyano, but (in common with many people) I'm sensitised to the stuff and can't use it anymore.

David Davis03/09/2013 06:25:28
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3598 forum posts
659 photos

If you didn't want to paint the lozenges by hand, there is, or was a firm called Wildmann Graphics which produces or used to produce pre-printed lozenge Solartex in a number of different scales.

I'm not sure whether they are still trading and I haven't been able to access the site, www.wildmanngraphics.net but the proprietor gave out his phone numbers on another website in 2009. These are 406 260 4088 or 406 871 0563. If phoning from outside the USA you will need to start with the international code 001.

Trevor Crook03/09/2013 22:14:46
923 forum posts
67 photos

Andy, if you don't fancy the lozenge, I found a scheme when I built mine years ago that was red and white, with a bird silhouette on the side. I think I got it from one of the Osprey books. I'm sure you'd find it by googling. Also, Herman Goering's one was all white.

jeff2wings03/09/2013 23:20:33
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804 forum posts
1967 photos

That will be Jasta 18 "Raben" ( Raven ) however ,they still have the lozange covering on the under side of the wings ,how about a all black one ?

imagesca7kq5oa.jpg

David Davis04/09/2013 05:11:03
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3598 forum posts
659 photos

If you don't fancy a lozenge finish, the Fokker DVII served in the airforces of Holland, Turkey, Poland and Russia amongst others, after the war. Some of these aircraft were finished in plain natural linen whilst others were painted olive drab all over.

Mind you, not finishing a DVII in lozenge colours is cheating! smiley

Andy Blackburn05/09/2013 22:08:25
510 forum posts
487 photos
1 articles

I tend to agree - for me, I think it's really got to be mostly lozenges. I was thinking of something like this:

munson-dvii001.jpg

...which is taken from "Fighters 1914-19 (Kenneth Munson, Blandford Press).

> ...I'm not sure whether they are still trading and I haven't been able to access the site,www.wildmanngraphics.net ...

I'm a bit wary of Wildmann Graphics because the website isn't available. On the other hand, Arizona Model Aircrafters have some custom-printed lozenge fabric (**LINK**) but it's only in 25 1/2" wide rolls, I'm not sure what sort of fabric it is, the colour seems to be a bit fragile (requires fuel-proofing using a spray, I assume that brush-painting the fuel proofer will smear the colours) and the underlying structure seems to require very specific preparation.

I don't really mind hand-painting, I'd just want to make sure that the edges of the lozenges look OK - straight, sharp, well-defined - difficult with a brush unless a mask is used. However, I think at the moment, that might be the least-fuss route.

Edited By Andy Blackburn on 05/09/2013 22:13:37

Andy Blackburn06/09/2013 12:41:50
510 forum posts
487 photos
1 articles

The top wing ribs are installed (with spars) and a right PITA they were too; they all needed to be 'persuaded' to straighten again using a thumbnail and/or steam from a kettle, and then glued in place quick before they warped again. Unfortunately, I was so fixated on the rib-straightening task that a couple of errors were committed along the way. Exhibit A:

top-wing-oops-1.jpg

A first sight, this probably looks fine but the main spar brace goes across the three middle bays, and one is supposed to split the middle two ribs and remove 1/16" for the ply brace. Drat.

Exhibit B is less serious:

top-wing-oops-2.jpg

- basically, I've used the wrong rib; the one in the middle of the picture should be at the wing-tip. Oh dear. At least it won't be visible when the wing is covered.

So, what I've done to fix the wing brace problem is to take the back off a razor-saw and use that to carefully cut a slot in the middle two ribs:

top-wing-brace-slot.jpg

...and then slide the brace into place, use a reasonable amount of Super Phatic and clamp everything:

top-wing-brace-installed.jpg

...which, with a bit of luck, should do the job.

Edited By Andy Blackburn on 06/09/2013 12:44:52

Andy Blackburn16/09/2013 18:29:46
510 forum posts
487 photos
1 articles

Had a busy few days, finally got round to making a bit more progress. The various aileron accessory bits have deviated from the plan as I'm using one servo per aileron - I didn't like the idea of screwing aileron horns into balsa reinforcement (part 102) and it had to change anyway because of the new pushrod position, so a bit of scrap 3mm liteply was substituted, chamfered so that it wouldn't get in the way of the TE scalloping (runny epoxy reinforcement will be added after scalloping the TE):

aileron-furniture.jpg

...and it looked to me as though the aileron-end-sub-ribs (if that's what you call them, part 99) were a bit too big - but I can't be the only one to notice this, and I don't remember anyone else saying anything about it. I'm generally loath to mess around with stuff that I don't really understand, but in the end decided to replace part 99 with a bit of scrap 1/4" balsa, as above.

And, here's where we've got to as of about an hour ago - the cap-strips are installed and I'm waiting for the glue to dry:

cap-strips-installed.jpg

There's a shocking amount of distortion in that picture, but I assure you that the ribs are (mainly) parallel .

The lower LE sheeting will be done later on this evening, then I need to clear the board for a bit of maintenance/repair work for a few days otherwise there'll be nothing available to fly at the weekend. Should be back to the build by the end of the week, though - ailerons are next...

Edited By Andy Blackburn on 16/09/2013 18:32:45

Andy Blackburn11/10/2013 17:44:46
510 forum posts
487 photos
1 articles

So it's been about four weeks - I've spent about two or three weeks making repairs (I now have 5 flyable power models and 5 flyable slopers) an hour or so cutting the ailerons and at least a week contemplating what to do about the resulting mistake...

I did briefly consider glossing over this (move along, nothing to see) but decided to come clean because a) to do otherwise wouldn't really be playing the game, and b) it might be of assistance to other people in a similar position.

The ailerons on the Flair D.VII are cut free from the wing, the aileron faces are chamfered and then both faces are lined with 3/16" sheet; this works OK but it does rather rely on the builder making the cut in the right place:

planning-aileron-cut-in-wrong-place.jpg

I think it's just possible to see in this picture that the pen marks for the port aileron cut are 3/16" too far towards the TE. I didn't notice...

aileron-template.jpg

...not even when the template for the aileron cut didn't line up with the plan; I might have got away with at that point if I hadn't cut the rest of the "waste" wood away on the aileron ribs...

aileron-spar.jpg

... and of course, it's only after the spar is added and the aileron offered up to see how it fits that it becomes obvious that something isn't quite right:

aileron-too-small.jpg

It's not easy to see on this picture (might have to use bigger pictures in future) but the port aileron seems to be about 1/8" too small in chord. Oh dear. (Not what I said at the time, of course).

It could have been worse, I suppose; it looks as though the port aileron facing will have to be 3/8", sanded down. It might not be so noticeable after everything is painted...

Edited By Andy Blackburn on 11/10/2013 17:47:48

Scott Edwards 223/10/2013 22:53:10
197 forum posts
96 photos

Relative to my cockups that only scores 1 out of 10 I'm afraid Just build the starboard aileron in exactly the same way. We shall not judge you.

If its any consolation, I've just built two left hand Lancaster ailerons. Thats a 3 out of 10 on the cockup scale and a full 10 on the nitwit range. I just laughed, drank tea, binned the worst one, and made a right hander, Theres always a way

Biggles' Elder Brother - Moderator24/10/2013 00:08:52
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15748 forum posts
1460 photos

The beauty of building in wood - most things are fixable! Even if in the end it does mean "build another one"! wink 2

Nice work Andy! Looking forward the start of the fuselage.

BEB

Andy Blackburn28/10/2013 15:12:41
510 forum posts
487 photos
1 articles

Had a very busy couple of weeks but all is now back to normal and am now getting back to building - many thanks for the messages of support and encouragement, BTW.

I eventually summoned up the courage to confront the cock-up and, in common with many of these things, it wasn't anything like as bad as I had feared.

This picture shows how one has to attach the aileron facing - prop up the aileron on some 1/8" sheet packing before gluing the facing, although in this case a bit more wood thickness was needed as I don't want to top-hinge the ailerons (the lozenge pattern on the ailerons usually runs span-wise rather than chord-wise on the wing and it should be easier to paint if it's separate.), so the standard 3/16" part was replaced by a piece of 1/4" sheet;

fitting-aileron-facing.jpg

This is the bodged aileron complete with 3/8" facing in situ with some tape on the surrounding wood to make the sanding easier - there's still a bit of a gap at the front.

aileron-bodge1.jpg

And this is the aileron spar proper more-or-less in place

aileron-bodge2.jpg

The pencil line is just a reference mark, not a cutting mark - The 3/8" sheet bodge needs about 1 mm taking off it at the tip to make a good fit, so some careful sanding will be required. The aileron is still about 3mm too wide in chord when the spar is attached, but that's not a problem because the hinge line will be dropped about 3mm which - with the hinge gap - will reduce the aileron width by a couple of millimetres, and the rest can just be sanded off. Here's what the right-hand aileron looks like with the surgery performed:

modified-aileron-hinge.jpg

And here's what it looks like when in place:

right-ail-mod-hinge.jpg

I think it's just possible to see that the top edge of the aileron is chamfered to accommodate the new hinge position; looking at it now, though, I think there might have to be a bit of local reinforcement behind the aileron spar to stop the covering producing a "starved horse" effect when it shrinks.

Edited By Andy Blackburn on 28/10/2013 15:14:57

Andy Blackburn02/12/2013 20:49:44
510 forum posts
487 photos
1 articles

I think I've discovered what goes wrong with builds - life just gets in the way

The ailerons are finally bodged to the point of being structurally finished; they don't look too bad, even if they're not quite the same:

bodged-ailerons.jpg

They're roughly sanded and appear to be straight, which is a bonus. There's a piece of 3/32" sheet on the inner face of the right aileron; I wish I could claim that this was intentional, but it wasn't. Let's just draw a discreet veil over the circumstances that required this minor corrective measure.

The plan is now to finish-sand everything, hinge the ailerons and install the servos, the strut fitment is still a bit up in the air but I'm thinking captive nuts for the centre section and am still weighing-up a couple of options for the interplane struts; I think it might depend how flexible the wings turn out to be.

 

Edited By Andy Blackburn on 02/12/2013 20:50:56

Andy Blackburn25/01/2014 14:16:09
510 forum posts
487 photos
1 articles

After 6 weeks or so doing other things I really need to focus on this build for a bit because a) I want to enter it in the club scale competition this year (June?) and b) the club winter projects meeting is in a few weeks time; it won't be finished by then but it'll be interesting to see whether the major components are done.

In view of the rather flexible wing structure, I've decided to leave the interplane strut fixings as they are but - following advice from a mate who has one of these - use 3mm allen-head bolts in place of the supplied items. The cabane struts will be fixed by bending the strut mounts horizontal (rather than vertical as on the plan) and having some fixed 3mm screws in the wing so that it just drops on (as discussed above), attached with some nyloc nuts using a nut driver; so for assembly, that's a total of 8 hex screws with anti-vibration washers, 4 nyloc nuts and a wing bolt. I suppose I can live with that.

Progress so far this week is: aileron servo hatch covers completed (1/16" ply and 1/2" square spruce - didn't have any obechi) and servos installed:

aileron-servo-on-hatch.jpg

...here's how it fits into the wing;

aileron-servo-installed.jpg

I think the hatch cover could do with a bit of sanding on three edges to equalise the gap, otherwise it won't fit properly when Solartexed.

As suspected, the right-hand aileron (the one made as per the plan, rather than bodged) looks as though it'll need a bit of extra wood to support the hinge:

dodgy-aileron-hinges.jpg

As you can probably see, the hinge is fitted quite close to the edge and there's not a lot of wood there. Of course, this wouldn't be a problem if the aileron had a Solartex hinge as on the plan.

 

Edited By Andy Blackburn on 25/01/2014 14:17:47

Stevo25/01/2014 16:17:05
2699 forum posts
419 photos

Your doing great!

Thats the way to hinge - just as I did and... I'm glad I did...

I cut my hinge slots around 30 degrees down from the horizontal, near the top of course, on both wing and aileron. I then bent the hing in the middle by 60 degrees, and glued in place. I ended up with a much tighter join, and none of that lifting that a 'tex hinge will give you.

I've made a few 'tex hinges, and the mating between control surface and wing has got to be absolutely precision. Even then, any movement in the timber or slight shrinkage in the covering makes them look awful..

Andy Blackburn25/01/2014 20:51:01
510 forum posts
487 photos
1 articles

Pinned hinges? I didn't think of using them, but it's a good idea - I've not used pinned hinges very often for some reason, but the way you've described it there, I'm sold. Thanks.

smiley

jeff2wings25/01/2014 21:20:44
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804 forum posts
1967 photos

And just to be different ,I used Robart hinge points centre mounted

imga0015.jpg

imga0016.jpg

Andy Blackburn26/01/2014 18:04:51
510 forum posts
487 photos
1 articles

Nicely done hinges - might seriously consider doing it that way next time.

Scott Edwards 227/01/2014 08:40:22
197 forum posts
96 photos

I'm a recent convert to Robart pin hinges, didnt use them for years as they looked 'orribly fiddly to line up but they are actually OK. I found you can make the hinge lines exactly on the top of the control surface, which I never managed to do with 'fuzzy' mylar hinges, or flat plastic hinges. The look quite cool too, as in Jeffs wing pic above !

Any more thoughts on the Lozenge pattern Andy, or how to achieve it ?

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