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Fokker DVII by Flair

WWI biplane kit build blog

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andy watson06/08/2008 20:24:00
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Well here we go.

DIY is more or less finished, and the long promised reward of a kit arrived from leeds models this morning.

As the thread title says it's a WW1 german biplane- the Fokker DVII, or Fokker D7.  I hope I won't upset purists by calling it the D7 but for some stupid reason I have started refering to it as the DV7  and need to get that out of my brain!  Bought from Leeds because the web price was £125 rather than the £135ish everywhere else, but when I phoned up the guy said it was £135.  Don't know if the web price was an error, or they didn't communicate it to the shop staff- but they immediately honoured the web price.  I did fail horribly in getting any discount as a school project- that's 2/2 failures, model shops are tough!! 

Anyway- slightly disappointed at the size of the box because it arrived in a huge box which was about 30% packing!  Seriously though everything was well packaged in and out of the box- so well done Flair & Leeds Models.  I have had a look at the plans, and they are pretty confusing at first glance, but a few hours has made them clearer.  I am already changing plans because I intended to start with the fuselage, but noticed it makes reference to cutting bits out for different engines.  As I have promised the other half there is no expenditure needed for a couple of months on a kit  I better leave that till last until I can sneak an engine through the bank account.  Bloody joint accounts!

I will be a bit more tolerant of the lack of definitive instructions since this is a kit, and says not for beginners- as opposed to the jumper 25, but here goes!!!!

andy watson06/08/2008 20:35:00
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1942 forum posts
20 photos

Well it starts out in a less than glamorous manner.

I tidy the office since it's a tip. 

I need a work table, so I cannibalise a table football table and take out the players and scoring markers to give a 4 foot level surface.  Stick a piece of 18mm ply across it, but it looks a bit flexible.  A root in the garage turns up 5' of kitchen worktop, so I stick that on top, screw a piece of 12mm plasterboard onto it, and I think I am ready to go!  Now I learned a lot from Alex's boomerang blog, so I will make an effort with pictures!

http://i45.photobucket.com/albums/f81/andywatson3/PICT0373.jpg

http://i45.photobucket.com/albums/f81/andywatson3/PICT0374.jpg

So that's the work area ready to go! 

And before I have even taken the safety cap off the knife or touched a piece of Balsa it's going horribly wrong.  In asking for the digital camera I have piqued interest in what I am up to, and she has seen the comment about the engine!!  Might be rubber powered then...............

andy watson06/08/2008 23:26:00
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1942 forum posts
20 photos

Caution is the better part of valour.

I start with the tail since it's a simple matter of cutting strip balsa to size and pinning it to the plan.  Immediately run into a dilemma about where to cut- middle of the line, outside, inside?  Sort it out easily enough.  Learnt one valuable lesson- put the precut bits in first!  The triangular piece was precut and was actually about 1mm shorter than on the plan.  No problem in that it meant the centre strut had to be moved back a mm or so, but might have led to a problem.

anyway.....here it is.

http://i45.photobucket.com/albums/f81/andywatson3/PICT0376.jpg


If the rest of the build is that straightforwards I will be a happy man!!

Still needs sanding to profile, but I will wait till it's sunny and do it outside.  Oh yes-  I learned valuable lesson #2.  Digital cameras don't work if you forget to put the memory card back in!!

andy watson07/08/2008 16:31:00
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1942 forum posts
20 photos

Continuing in the vein of getting the easy bits out of the way, it's time for the rudder.

Been reading about flying the D7 and biplanes in general, and they all mention that the rudder is a much more important control than it is in my trainer, so that will be why it is so big then!

Initial reading of the plans led me to think it was a simple build straight onto the plan for most of it, with a 3mm liteply outside edge that needed supporting to be half way up the 6mm thick balsa used for the rest.  A secong (probably 5th) reading actually made me realise that the liteply needed doubling up, so they were glued togather first before constucting it over the plan just like the tailplane.  The rerason for the confusion was to allow the correct chamfered profile to the edge of the rudder, but the plans implied it should be sanded before construction (and would thus need propping up to halfway).  This seems silly- and I will sand it after construction.

http://i45.photobucket.com/albums/f81/andywatson3/PICT0377.jpg

All easy enough, but I was disappoonted to see one of the liteply pieces doesn't actually match the plan- the curvature is quite different.

http://i45.photobucket.com/albums/f81/andywatson3/PICT0379.jpg

I'm not sure if it's clear but part 44 isn't as rounded as the plan.  Now it makes no difference to the build- a bit of fiddling and a slight change in shape, but I would have thought either the plan could have been ammended to fit the piece, or vice versa.  A small amount of sanding/trimming is needed to complete, but it's basically done.

One issue, if anyone is reading, is there is a piece of wood added to the bottom of the rudder for the control horn.  It isn't labelled on the plans- is balsa ok, or should I have used ply?

Myron Beaumont07/08/2008 22:52:00
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5797 forum posts
51 photos

Yep! I'm reading   I would use balsa & impregnate it with superglue  Of course I can't see the actual plan but just try to imagine the type of stress involved .Use ply or a laminate of balsa in different grain directions OR one of my favourites =balsa with very thin ply each side == very strong

andy watson08/08/2008 01:19:00
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1942 forum posts
20 photos

Cheers Myron,

My thoughts were a few short screws wouldn't be as strong as I might hope given the size of the rudder, the leverage might cause the screws to work lose/pull out.  I figure prevention will be better than cure, so given that I have already glued the block in I will either

a) find scrap ply then shave off enough balsa to replace it

b) flood the balsa with superglue to strengthen it.  You use the term inpregnate it- do you mean to pierce the balsa in any way to help penetration of the cyano

Myron Beaumont08/08/2008 06:31:00
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5797 forum posts
51 photos

Andy

I suppose you could  Using thin cyano it shouldn't be necessary.  If the balsa is rock hard then a rew pin holes wouldn't go amiss Personally  I'd go for the 1/32 "ish ply option for real peace of mind.

David Ashby - Moderator08/08/2008 07:56:00
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Really interesting blog Andy - look forward to seeing her progress, good stuff.
andy watson08/08/2008 17:28:00
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1942 forum posts
20 photos

There has been more progress today, but I felt this should have a message to itself- and it's a simple apology to Flair.

When doing the rudder I said I was disappointed that the curvature of one of the pieces didn't match that of the plan.  Well it would have done if I'd got the right bit!  I started the elevators this morning to realise one of the pieces I needed was already out of the sheet- and sure enough it was nicely glued into my rudder.

In some small degree of mitigation the pieces do look very similar and were close together on the ply sheet- I just removed the wrong one!  I will make sure I check more carefully in the future.

Anyway- I saw on another thread how seriously kit manufacturers take criticisms of their kits, and I want to make clear that this was my mistake, and the correct piece does indeed fit exactly as per the plan!

Myron Beaumont08/08/2008 20:46:00
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5797 forum posts
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Andy

Whoops .Reminds me of the old adage" measure twice cut once" I think we've all nearly done it .Thats life ! Third wife !

andy watson08/08/2008 22:06:00
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1942 forum posts
20 photos

I was a bit grumpy at myself, but I did feel the most important thing was to make clear where the error lay.  I know when I was looking at which kit to buy I looked at assorted reviews and building blogs- and I wouldn't like mine to unfairly influence someone.  I will certainly make extra sure where a piece doesn't appear to match the plan that I have the right piece!

Anyway, onwards and upwards.

I spent a bit of time this morning carefully cutting out the wrong piece from the rudder.  I replaced it with the right piece and had to recut some stuts as the shape was different.  It was a bit time consuming, but not too bad.  Certainly it could have been much worse.  I decided to leave the balsa fillet in place that the horn will screw into.  It does seem pretty sturdy, and I am confident the screws will hold.

So onto making some progress, and the fin was a simple construction all from stock strip.  Only took a short time to build, and once complete it sits absolutely flush with the rudder. 

http://i45.photobucket.com/albums/f81/andywatson3/PICT0383.jpg


Elevator this afternoon, and they are a mix of light-ply curved edges, strip balsa and a tapered training edge.  The overall shape is quite complicated, but the excellent ply edging makes it very simple.  Like the rudder pieces the final piece is 6mm thick, and made from 2 3mm thick pieces of ply which are glued together before construction.  The rest is straightforwards.  Both have a triangular block in place to allow the connecting wire into.  I decided to make the starboard one from ply since the control horn will screw in there for extra security, the other is balsa.  When I was sanding the trailing edge curve I held both halves together to ensure both ended up identical.

http://i45.photobucket.com/albums/f81/andywatson3/PICT0380.jpg

The 2 elevator halves are connected by a bent piece of 14SWG wire.  I wish it had been supplied bent, because it is bloody strong!  Using a pair of mole grips I managed to get them bent in the right place, and just about flat.  A small amount of twisting got it spot on.  I put the 2 halves on the plan and laid the wire on top of the balsa structure.  I marked up the lines for the holes.  I was a bit worried about using a drill on them, since the wood is very soft, and tried to drill it by hand- that wasn't brilliant, so I used a cordless screwdriver as a drill and a more controlable compromise.  I then cut grooves for the wire to sit in, tried a dry fit before epoxying the wire in place.

http://i45.photobucket.com/albums/f81/andywatson3/PICT0382.jpg

andy watson10/08/2008 21:18:00
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1942 forum posts
20 photos

Bah, IE had a problem and needed to close, so no post yesterday- not that this meant there was no progress.

I am forced to go outside to enjoy a cigarette on the unreasonable basis that it is smelly and unhealthy.  I took advantage of this to use my time outside to sand the assorted pieces of tail to their appropriate profiles.  It was slightly timeconsuming, but since I was outside anyway, it passed the time quite pleasantly.  Doing the sanding outside also kept the natives onside since I didn't fill the house with dust!  I then decided to mess around with some masking tape and put the complete tail assembly together.

http://i45.photobucket.com/albums/f81/andywatson3/PICT0386.jpg

http://i45.photobucket.com/albums/f81/andywatson3/PICT0385.jpg

http://i45.photobucket.com/albums/f81/andywatson3/PICT0384.jpg

andy watson10/08/2008 21:49:00
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1942 forum posts
20 photos

Having completed the basic tail structure I decided to move onto the rear fuselage.  The fuselage is built in 2 distinct parts- the forward section is boxed in and balsa sheeted.  I can't do this bit until I buy an engine though, and I have been dropping gentle hints about pay day not being too far off!

So rear fuselage it is, and this is very simple- 2 identical sides built up out of strip, then cross members added to bring it to the correct shape.  I know the top doesn't look straight- there is a deliberate angle built in for the tail plane to sit on!

http://i45.photobucket.com/albums/f81/andywatson3/PICT0387.jpg


http://i45.photobucket.com/albums/f81/andywatson3/PICT0406.jpg


http://i45.photobucket.com/albums/f81/andywatson3/PICT0407.jpg

Adding the crossmembers was made easy by a plan view of the assembly, so I cut the parts, pinned 2 sides to the plan view and glued the cross pieces in place.  This did take a while though, because I was extremely careful to get everything square and straight.  Good job really as when I was moving onto the next section I realised that the other sheet that deals with the front fuselage says to build that, then attach the 2 sides to the front half before bringing the 2 sides together.  It is a bit awkward sometimes- these plans are on 5 sheets, and sometimes there are references on other sheets to the bits you make on another.  In fairness most people would instinctively start with the front of the fuselage and notice this.  Anyway, it all looks straight, so I am confident there won't be a problem later.  I have epoxied the triangle for the tail skid to attach to, but on the plans it says to bind the skid on before glueing.  Unfortunately I have no idea what to use for this binding (nothing is supplied), so ideas are welcome.  At this point I should remind you that I am (at best) on the lowest level of experience suggested for this kit, and I assume this is a standard process that most builders would be familiar with.

andy watson10/08/2008 22:52:00
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1942 forum posts
20 photos

Well the rear fuse didn't take a full day, so it is time to bite the bullet and move onto something a bit more technical!  Since there are basically only the wings to do apart from the fuselage I had a look at the plans and quickly realised the lower wings were the simplest of the 2 to build- no messing with ailerons and the like.  I also quickly realised that although the wings were on 2 seperate plans they were built as 1 wing.  This gave cause for concern on 2 levels- 1 about whether the finished beast will fit in my car (will be ok really), but more importantly that the plans need joining together.  There are clear markings showing where to trim and join the plan, but being extra careful to line everything up correctly meant I took a good while to do this.

I don't know how common this is, but there was a warning in the instructions about the possibility of the paper moving during printing.   It was apparant that this must have happened on my plans, because when the trailing edge was level there was a marked gap between the leading adge and some of the forward members on the plan.  In effect one wing is narrower than the other by about 1.5mm. 

http://i45.photobucket.com/albums/f81/andywatson3/PICT0408.jpg

It might be a common problem, but I don't really think this is good enough. 

Reading the instructions I saw the first thing I had to do was scarf join the trailing edge and leading edge sheet.  Once I had done a quick google to find out what a scarf joint was  (The plan actually showed it) I then set about fretting how to make sure it was 100% straight, as I was already worried about the wings being straight due to the printing.  In the end it was actually very straightforwards.  I put the trailing edge pieces on the plan, overlapped where the join was to be.  This was to make sure  didn't accidently make them too short.  I then pulled them out slightly to make double sure .  In truth there was no need to worry as there was plenty of wood.  I then laid both bits of wood up against a straight edge and carefully cut my angle through both bits.  The wood was thin enough that this was simple.  I then put them together, and pinned them in place again using the straightedge to ensure accuracy and ran cyano along the gap.  I repeated the process for the leading edge.

Feeling pretty pleased with myself, I took myself off for another read of the plans and bed to think about what to do with the mismatched wing plans.

andy watson10/08/2008 23:24:00
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1942 forum posts
20 photos

So, back up to date, and I awoke this morning none the wiser about the differing wing thicknesses.  I decided to pin the trailing edge in place, since that was alligned perfectly (I used that to set the position of the plan).  I couldn't pin the leading edge though, as I didn't have a full length straight line to follow.  In the end  left it unpinned, and started dry fitting the other parts.  There was an undercarriage block and some more sheeting, then the rib caps.  The rib caps ran from the trailing edge to the leading edge sheet, and I realised that if the wings were square then each rib cap would have to be an identical length.  Picking the wider starboard wing as the true one, I carefully measured and cut a cap.  I then made sure I used this single cap as a template for all the others.  I thought if I just cut a new one from the last I might have got a creeping error in my cuts.  Once they were all cut and in place I could use them to position my leading edge perfectly straight, so although it was worked backwards from the design, it worked me around the problem perfectly.   With an accurate leading edge in place I could then fit in the undercarriage block and the lower sheeting. 

One big advantage of my poring over the leading edge problem was I had become very familiar with the build process of the wings, and progress was rapid from this point onwards.  Main strut across the bottom, then fixing the ribs to that, and using the ribs to position the rear strut.  Not sure why I couldn't glue both struts down initially, since it came out exactly to the plan!  Just in case of the printing I guess!  Then assorted strengthening bits and pieces joining the struts for reinforcement.  2 holes drilled into one piece for dowels to attach the wing to the fuselage and it was almost done when another problem stopped me in my tracks.  I ran out of superglue!   So with my leading edge half glued on I have had to stop.  One place I did have a minor hiccup was in placing some of the parts over the central sheeting area.  I wanted to check that they were actually supposed to go where I thought they should go, but the only place to check was on the plan.  Unfortunately the plan was blocked by the sheeting.  Since I have all the ribs, struts etc already in place, I figured if the wing wouldn't stay true now it never will and removed it from the plan a few steps before the instructions said to. 

http://i45.photobucket.com/albums/f81/andywatson3/PICT0397.jpg


http://i45.photobucket.com/albums/f81/andywatson3/PICT0399.jpg


http://i45.photobucket.com/albums/f81/andywatson3/PICT0398.jpg

andy watson10/08/2008 23:30:00
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1942 forum posts
20 photos

Since it's Sunday, and the shops are closed I can't buy any more glue till tomorrow.  My only alternative was to join the missus in the front room to watch big brother, so I decided to mess around with what I have done.  A bit of masking tape and some imagination, and it's starting to take shape!!

http://i45.photobucket.com/albums/f81/andywatson3/PICT0400.jpg



http://i45.photobucket.com/albums/f81/andywatson3/PICT0401.jpg




http://i45.photobucket.com/albums/f81/andywatson3/PICT0402.jpg




http://i45.photobucket.com/albums/f81/andywatson3/PICT0403.jpg




http://i45.photobucket.com/albums/f81/andywatson3/PICT0404.jpg




http://i45.photobucket.com/albums/f81/andywatson3/PICT0405-1.jpg



The tail plane is at too steep an angle because the fuselage is just laid flat.  In the completed model it will be lifted up and reduce the tailplanes' angle. (I think)
 
andy watson12/08/2008 18:26:00
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1942 forum posts
20 photos

Done a lot of work since the last post, but it doesn't look like it!

Really it is simply finishing the wing.

Bought some Bob Smith extra thin cyano.  Wow, they really aren't joking when they call it extra thin.  I cut the tip off the bottle, and had tilted the bottle downwards to rest the tip on the board.  One cut and suddenly there was cyano shooting everywhere!  This stuff just pours out given half a chance.  In fact it can be too uncontrollable!  Not sure if it possible to buy thin rather than extra thin, but it does run into joints really well.  Maybe it's practice that's needed. 

Anyway, onto the build and it was a simple job to glue the second piece of leading edge in place.  I then glued a plywood brace in place, before belatedly realiseing it needed drilling out to accept the dowels to connect the wing to the fuselage. .  A bit of careful measuring, and some awkward marking out meant I could drill them in situ.  The dowels were run though the holes and the leading edges sanded down to allow them to run out parallel.  The top of the centre section was sheeted, and the rib caps added. 

http://i45.photobucket.com/albums/f81/andywatson3/PICT0415.jpg

http://i45.photobucket.com/albums/f81/andywatson3/PICT0416.jpg

The lower front sheeting now needed bending up to meet the leading edge.  I painted water onto the sheet to soften it, and it curved up without any problems, well except one minor one.  Where the wood was scarf joined it was much more brittle, and didn't bend as easily as the non-joined parts.  The join isn't as clean here because of this, but as it's going to be tucked away in the fuselage I don't suppose it matters. The wing tips were simply glued on, along with a couple of fillets to strengthen them (or possibly to shape the covering). 

andy watson12/08/2008 18:27:00
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1942 forum posts
20 photos

Onto the joys of sanding to shape the leading edge!  Actually it was quicker than I expected.  I use 80 grade to get a rough shape, then 180 to smooth it off.  I will give it a final rub with something finer before covering, but I shaped the leading edge, and also went over where the rib caps meet the sheet to ensure there are no bumps there.  There are a couple of bits to add to the top of the centre sheeted area- I think to support the join, but I will leave these until I have the fuselage built so I can check the fit.

http://i45.photobucket.com/albums/f81/andywatson3/PICT0417.jpg

Final job on the wings was the scalloping.  I have to be honest, I had mixed feelings about this.  I wasn't sure if I liked it, or not.  Seriously tempted to leave it with a straight edge, I went with the design and made a cardboard template.  I then simply used the template to mark out the scallops- simple as they fall between all the ribs- and cut them out.  I then clamped them in the middle of the curve and ran cyano the length of the wing.  A gentle sand smoothed out the rough bits, and the knife levered off the couple of clamps I had glued to the wing .  Once done I have to say I really like them.  They are a lot more subtle than I expected them to look, but I can imagine they will be a pain to cover!

http://i45.photobucket.com/albums/f81/andywatson3/PICT0418-1.jpg


http://i45.photobucket.com/albums/f81/andywatson3/PICT0419.jpg

andy watson12/08/2008 18:42:00
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1942 forum posts
20 photos

I am starting on the upper wing- it's much bigger than the lower.  59" span compared to 51" for the lower wing (funny, the box claims a span of 61" ) but the main difference is the width (chord?) with the lower 8" and the upper 11 1/2".  The instructions say to build it in the same way as the lower wing, then cut out the ailerons- which sounds a stupid and difficult way of doing things.  I'm sure there is a reason for that, but I really don't know what it is.

Anyway, I have a problem with the servos, although since no one can help me with the binding of the tail skid question from a couple of days ago, then maybe I am asking myself these questions!

The plans show a quite complicated set up of a single servo in the fuselage connected to the 2 ailerons by a pushrod going up into the wing and then a bellcrank set up operating the ailerons.  Seems a bit Heath Robinson, but sort of makes sense.  My concern with this method is the hardwiring of the ailerons to the fuselage servo- surely this means the wing cannot be removed, or the servo will get realigned every time?

The other alternative is to use 2 servos, one in each wing and a "Y" connector.  As far as I can see this would mean shorter rods and less parts to go wrong.  Would this be preferable?  The wing is 11/2" thich at this point, and looking around I have seen 2 methods- the servo upside down so the whole arm sticks out of the bottom of the wing, or the servo on it's side with the arm sticking through the bottom of the wing.  Is either better than the other? Presumably either method will require some kind of "service hatch" in each wing.

As a final question- since I am in the mood  can anyone recommend a servo?  I will be using a standard Futaba R607FX 2.4GHz receiver.  I am assuming the standard S3003 servos will be fine, but are they recommended?

Myron Beaumont12/08/2008 19:33:00
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5797 forum posts
51 photos

Andy

I use a S3003 on my Flair Puppeteer .It works the four Ailerons just fine ! In fact they  are the most used servos by me Apart from Hi Tec's

By the way -Do you write your blog as you build ? I'm sure it is very helpful to folks who follow on from your good self . Learn as you go  Eh! Well done -Keep up the good work & by the way I use Solartex to cover for lots of reasons already discussed on other threads

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