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Planes => Delta Wings and Funjets Section => Topic started by: Andy Sayle on February 09, 2016, 11:47:37 AM

Title: Andy's Drak
Post by: Andy Sayle on February 09, 2016, 11:47:37 AM
Rather than jump all over Mutley's thread on his Drak build, I thought I'd do my own.  I ordered a nice pair of Draks (Draken? not sure what the plural of Drak is.) last year after seeing the kickstarter that Chris of Ritewing did.  It looked like it would fit my needs perfectly.

I wanted something bigger than a fun jet, but a similar layout.  Something that can cruise fast, and carry a decent payload.  Something that is robust and can handle rough landing sites.  The Drak will do all this, it looks a bit like a funjet if I take my glasses off. And squint. Quite a bit of squinting actually.  Its the right layout anyway, pusher, eleven controlled, pointy nose.  And it has a vast fuselage.  Really big.  And if that wasn't enough, there are two saddle bays in the wing roots too!  Just the ticket.

Feeling flush, and after selling a few multirotor kits, I ordered two.  The idea was to build one up for fast FPV action, and another to have a foray into mapping, with a down facing CSC camera in the fuselage.  There should be plenty of room for my Sony A6000 to mount nicely. 

The kits came, and I have cleared my workbench for the build.  Sort of.  The workshop is like a bombsite. Organised chaos you could call it.  The quality of the kit is outstanding.  The EPP foam mouldings are all great, a silvery grey colour and quite high density too.  The foam is very sturdy, but with a little bit of give.  It should take an impact very nicely indeed.  The downside to this is a bit of extra weight, the foam components don't feel as light as they perhaps could be.  You can't have everything though, and as this is never intended to be a lightweight floater of a model, Mr Ritewing made a good choice.  The accessories are great too, some cleanly cut Correx fins and compartment lids, a bundle of spars, a bag of thumb screws and some threaded inserts, a formed ally motor mount and a roll of laminate.  So, on with the build!  Oh, have a look here:  http://www.fpvhub.com/index.php/topic,48115.0.html (http://www.fpvhub.com/index.php/topic,48115.0.html)  for some nice pictures of the Drak components, along with Mutley's choice of equipment that he is putting in his...  I'll decide the stuff to go in mine, as I go along I think...

First up was the elevons. These are foam, and are designed to have some 1mm glass spars bonded in with Goop.  Before this can be done, some EPP lumps need trimming off, these are presumably part of the moulding process.  I used a new snapoff knife blade to cut the lumps off cleanly, and accidentally cut a bit of my finger too.  Blood all over the place, which has to be a good omen right?  Any model that draws blood is going to be good... 

The moulded grooves for the spars stop just short of the end of the elevons, so I melted the slot out on one end to extend it.  This will allow me to leave the spars too long, but have something to hold on to whilst manipulating them in the slots (and not getting myself covered with Goop!).   I  taped the elevons down to the workbench to hold them flat, ran a bead of goop in the slot and pressed the spar in with a rolling action.  This should make sure the spar is evenly bonded in the moulded EPP slot.  I had to press it down a little to get it to the bottom of the slot, using a little pokey stick.  I then ran another small bead of goop over the top, and smoothed it out using a wet fingertip.  This is being left to dry for a day whilst work gets in the way of things... 

I also did the top side of the wings whilst I had the fans on (did I mention Goop stinks!), these have two spars in the top, and two in the bottom.  No pictures yet, phone battery had died....

I'll do the other sides when they are properly dry, although the wings need to have the spar tubes bonded in first.

More later.....
Title: Re: Andy's Drak
Post by: Andy Sayle on February 09, 2016, 11:50:28 AM
Oh, did I mention I ordered one of the motors and ESC's that Mr Ritewing sells specifically for the Drak?  Well I did.  Very nice quality motor, and the ESC looks like an ESC.  We shall see how that works later, as that is getting installed in the mapping machine.  This will be built reasonably lightly.  The FPV machine though, I am debating whether to put an "adequate" powertrain in it.  Roughly translated, that means stupidly overpowered....

We shall see....
Title: Re: Andy's Drak
Post by: Coyote on February 09, 2016, 12:56:36 PM
Cool another build ! Like a bit of variety :)
Title: Andy's Drak
Post by: Cockney Boy on February 09, 2016, 02:30:03 PM
Proper tempted to buy one but it would be packaged in Divorce papers :(
Title: Re: Andy's Drak
Post by: Billy_boy_2010 on February 09, 2016, 11:38:46 PM
Looking good so far.

Please tell me you're running it on 6s. Seems the perfect plane for a fast 6s setup but with the potential for a semi sensible cruise current?
Title: Re: Andy's Drak
Post by: Andy Sayle on February 10, 2016, 12:23:46 AM
I'm in a dilemma with the power setup.  On the one hand I have the ritewing motor and esc, optimised for 5s.  On the other hand I could ditch those, and fit a setup for 6s.  Or even 8s.  I use a fair few 4s packs on other stuff, so doubling up in series would be an option...  I think I may stick with the ritewing setup on the mapping plane, and have some fun with the other...
Title: Re: Andy's Drak
Post by: wgt40w on February 10, 2016, 10:28:33 AM
Quote from: Andy Sayle on February 10, 2016, 12:23:46 AM
I'm in a dilemma with the power setup.  On the one hand I have the ritewing motor and esc, optimised for 5s.  On the other hand I could ditch those, and fit a setup for 6s.  Or even 8s.  I use a fair few 4s packs on other stuff, so doubling up in series would be an option...  I think I may stick with the ritewing setup on the mapping plane, and have some fun with the other...

If a mapping plane is flown too fast, at an unsuitable low altitude, might that mean:-

1) You get insufficient image overlap?

2) Images are slightly blurred?
Title: Re: Andy's Drak
Post by: Andy Sayle on February 10, 2016, 10:33:59 AM
That's what I'm thinking too.  I've slept on it (not literally) and I think I'll use the Ritewing setup for the mapping beastie, mainly because I already have it.  And as for the FPV ship, that shall be treated to a monster of a powertrain.  I'm going to have a look at ecalc now, and run some numbers to see what sort of motor I should be aiming at for a big power 4 or 8s setup.  I'm leaning towards running a pair of 4s in series, and getting the power from voltage, rather than high currents.  That way I can use a lighter ESC, cables, connectors etc.

Oh, and bragging rights ;)

Andy
Title: Re: Andy's Drak
Post by: Andy Sayle on February 10, 2016, 01:06:57 PM
This build is great.  It's been a while since my building mojo has been in attendance, but this kit is going together really nicely.  It seems to be really well thought out.  Anyway, here's some more pictures too, of things like the moulded in spar grooves, and where I melted the ends away a bit so I can keep the spars too long, which makes them easier to manipulate when covered in Goop.  Which, incidentally, is possibly the second most sticky substance known to man.  The first being snot from a 2 year old.  The glued finish is pretty good.  It seems that most of Goop is solvent that disappears overnight, leaving about 50% of the stuff behind as a tough rubbery layer.  As a result, the finish is not nice and smooth like when it was applied, but it leaves behind a little trench.  I may fill these in.  Then again, I may not.  I'll  probably laminate the fast FPV ship wings, so it's not essential there I reckon.

There should be some pictures of the motor mount.  This is an ally plate glued to the fuselage, and with a covering foam moulding over the top, to make a sandwich.  There is then an adjustable folded ally part that motor bolts to, and this can be positioned fore/aft to suit on the plate when it is glued in.  This was a bit of a pain to get lined up when bonding, as the parts tended to slide about a fair bit.  I used plenty of Goop here, and a bit of pressure from some clamps to squeeze the excess out.  You can't see, but I put a few pins in to hold it in the right place overnight.

The end result is a really strong motor mount, with a tiny bit of give in the foam.  Perfect for absorbing knocks on landing.  Oh, the formed motor mount bit, can also be orientated so the motor doesn't scrape on the ground on landing.  Clever stuff from Mr Ritewing.  Surprisingly light too!

Next job, is spar tubes.  Measure these to length, and cut using my trusty razor saw.  A new blade would have helped here, but who wants to wait around for a delivery of new blades?!  Make doubly, no triply sure that you remove the actual spar from inside the spar tubes here!  They are shipped one inside the other, and the last thing you want to do is cut the spar at the same time as the tube!  I wrapped a bit of tape around the tubes before cutting.  It helps stop splintering of carbon tubes I find...

Once they are cut to size, I took the shine off the tubes with a bit of 120 grit sandpaper, used very lightly.  This should help get the best bond, not many adhesives like shiny surfaces.  Wipe down with alcohol to get the dust off, and they are ready to be installed in the wings/fuselage.  I did an alignment check on the dining room table (Shhh, don't tell SWMBO), and the alignment is pretty good with no adjustment needed.  The tubes were bonded in along the bottom with Goop, and left to cure overnight.  I'll glue the foam caps in place when this is set, so not to risk them moving about too much.

That was it for last night, the Goop fumes were making me dizzy.
Title: Re: Andy's Drak
Post by: Andy Sayle on February 11, 2016, 10:52:45 AM
Another couple of hours spent on the Draks last night.  As the spar tubes are nicely bonded in place, I couldn't resist a quick assemble to see what it looked like.  A decent size is probably the words I would use to describe it.  I did notice that the Goop drying had pulled one of the spar tubes slightly off centre.  Not so much to cause any major issues when assembling, but enough to be noticeable.  It might be worth pinning the spar tubes in place to stop this happening if I ever build another.

Now spar tube caps.  These are more EPP foam mouldings, but they are quite a loose fit in the slots.  Apparently this is so that a foaming adhesive can be used, and allow the spar tubes to be positioned perfectly.   Given the fact that accurate airfoils can be made in EPP, I'd like to think that a nice fitting spar tube recess could also be made  Ah well, out with the foaming polyurethane glue.  I'm going to mix this with some quality American wood glue, to make sure it foams up nicely.  The PU glue basically reacts with moisture, which it gets from the wood glue.  Any pva, or white glue would do the trick.  Even using a small bit of water would probably work too.

I followed Mr Ritewing's build video for gluing these caps in.  A smnall amount of foaming PU glue on the spar, a bit of goop on the EPP-EPP bit, and a bead of hot glue around the top, to ensure the small bit of foam doesn't move, whilst the other glues foam up, and move around to fill the gaps up.  A good tip is to not put a massive amount of the foamy glue on here.  After a few minutes it all starts to get a bit messy.

Once all the spar caps for the wings were in place, I did the fuselage spar caps too.  These are much bigger chunks of foam, so it takes a bit of preparation, and speedy work with the hot glue gun to get them held in place before the foamy PU glue starts expanding.

Whilst I had the hot glue gun powered up, I also did the bottom of the fuselage stringers.  These are done in a similar way to the wings, with the exception of the slots not being straight.  I used a bead of goop on the straight bits, and hot glue on the bendy bits, and a number of T pins to hold the spar in place whilst everything sets.  I'll do the top sides on the next building session, as well as trim excess glue and fill any gaps left on the spar caps.

After that, I think most of the gluey stuff, is done, and it is on to painting/laminating/making stuff look pretty.  Oh, I better route some wiring before the laminating too.
Title: Re: Andy's Drak
Post by: mutley2 on February 11, 2016, 11:49:22 AM
Coming on a treat, my capping's were a little short, good to see your are the right length.
Title: Re: Andy's Drak
Post by: Andy Sayle on February 11, 2016, 12:30:00 PM
I was quite glad too.  They are far too long for the wings, but about 10mm longer than the slots in the fuselage.  I'll trim them back with some side cutters when the glue is cured/dried/glued.

I forgot to mention above, that the spar cap mouldings in my kits, were about 5mm too short too.  I whipped out SWMBO hairdryer, warmed them up, and stretched them by hand.  It worked a treat.

Title: Re: Andy's Drak
Post by: Billy_boy_2010 on February 11, 2016, 08:12:13 PM
Looking good so far.

It's a really quick build by the looks of things.

Really must resist!
Title: Re: Andy's Drak
Post by: Andy Sayle on February 12, 2016, 11:46:54 AM
Yeah, it is going together quickly.  So far, I'm impressed with the kits.  There are a couple of little niggles but that is just me being really picky, like the spar tube foam caps being a little distorted or on the small side, but I can see my Mr Ritewing has done it that way.  Including the control horns and links would have been a nice touch too, instead of having to buy them separately (guess which bits I forgot to order!).

Oh, and, Resistance is Futile.  Apparently....
Title: Re: Andy's Drak
Post by: Andy Sayle on February 12, 2016, 11:47:57 AM
Here's another build update too.  It was just a quick building session last night.  First up was to inspect the foamey PU glued in spar caps, and see if they have distorted or gone wrong at all.  Other than me putting a bit too much glue mix in, and it foaming out of the ends, it seems to have worked really well.  I had a few little puddles of cured foam on the floor of my little workshop, but luckily I put a sheet of plastic down to catch them!  These trimmed off fairly easily with a sharp knife (that bit me.  Another Drak related injury).  On a few of them, there was a little bit of glue that had crept into the spar tube.  Again, this trimmed off nicely with a sharp scalpel, and a little bit of sanding.

Once these were cleaned up, I installed the remaining little fibreglass spars on the underside of the wings, and top of the fuselage.  Exactly the same methods were used as before, so no pictures.  I also filled a few of the gaps in the spar caps with some Goop whilst I had a fresh tube open.

Once that lot is dry, I'll glue a couple of blocks of foam inside the fuselage to make a few equipment bays and that is pretty much it for big gluey type jobs.  So I'll start thinking about wiring, and cutting some channels for that.   Once that is done, I'll get some laminating done.  I'm definitely doing the elevons, and the wings for the fast FPV ship.  As for the wings on the mapping type one, I'm tempted to leave as is for now, to save a bit of weight.  I'm undecided on whether to lam the fuselage too.  On the one hand it will add even more strength, and impact/wear resistance to the underside.  On the other hand, there are compound curves all over the place, which will make it a pain to do.  I'd welcome opinions on this!

I've been having a think about colour schemes too.  I'm toying with the idea of getting a bit creative with some black sharpie markers and maybe a bit of brush applied plastidip in either bright green or bright orange applied direct to the EPP, underneath the laminate.  This should last nicely.  The alternative, is some lightweight printed vinyl (or applique type Profilm) applied over the laminate.  I've done that on wings before, and whilst it adds a bit of weight, it looks amazing.  The advantage of that is that it can easily be replaced, or changed at a later date too.  Although, anything under the laminate can just be covered over too I suppose!

Cheers
Andy
Title: Re: Andy's Drak
Post by: Andy Sayle on February 13, 2016, 10:53:49 PM
I did done a bit more last night.  The first bit, was to cut and glue in a block of epp to support the ends of the two piece correx covers for the main fuselage bay.  Mr Ritewing supplied a nice chunky lump of EPP moulded to fit snugly in the forward section of the fuselage bay.  I wish more kit suppliers did this, it's a cracking idea.  Anyway, I cut the back end off to sit where the covers meet in the middle, around 55mm thick.  I gooped it in place but cut a few channels to clear the spar tube, and wiring channels down the edges of the fuselage bay (did I mention them?  Another cracking idea from Mr Ritewing, recessed wiring channels down the full length of the fuselage bay).

Once this was dry, I made some little holes for the threaded inserts using a bit of hot wire.  The inserts screw into the foam with a hex key, and should be plenty strong enough to hold the covers in place.  I added a small amount of goop to the threads biting into the epp foam, just to make sure they stay put.

Another little job completed was to cut a few slots in the servo bays in the wing so that my servos of choice drop straight in with a nice snug fit.  I used a bit of 1.5mm wire heated with a gas torch to melt some channels through the foam for the wiring too, and then made corresponding channels into the fuselage saddlebays, and through to the main fuselage bay.  I may add more holes there for other stuff in the future.

Finally, I made a couple of servo extension leads to the vector FC that I am intending to mount in the rear bay for the fuselage.  I layed it all out using some pins to hold things in place to see how to route everything.  The ESC fits aft of the rear spar tube, Vector main unit and current sensor in front of the rear spar tube, and the gps puck thing sank into the foam I mounted above.  I'll probably bung the receiver in one of the saddle bays, and the vtx in the other saddle bay to give them a bit of separation.

I also had a tinker with a bit of spare foam.  I had this idea in my head of doing some tribal design type thing on the wing, using some black markers.  It turns out that Laminating film doesn't stick well at all to wherever the ink is, so it's back to the drawing board for that idea.  The lam that came with the kit sticks fantastically well to the bare EPP though, so the other idea of laminating and then using either profilm or printed vinyl is looking favourite at the moment.

Oh, and has anyone got any experience of mounting the vector about 5 inches aft of the CG location.  The manual says it should be as close as possible.  That's not going to happen here though...

More tomorrow night hopefully...

Andy
Title: Re: Andy's Drak
Post by: Andy Sayle on February 23, 2016, 12:34:04 PM
So after a week or so interlude on holiday, I'm back on the Drak build(s).  As the drawn ink under the lam wasn't going to work, I've made a start on laminating the elevons and wings.  Only a couple of pictures, as it is damn difficult to hold a chunk of foam, and covering iron, and a camera with only two hands.  I used the laminating film from Mr Ritewing, it is marginally thicker than the stuff I am used to, but on a test piece it doesn't half stick well to bare EPP.

I started with the elevons, and used a couple of pieces, wrapped around the hinge side of the elevon.  I found it was important to start in the middle of the elevon, and work outwards, to minimise any distortion.  This seemed to work well, although there is a slight bow that has been introduced.  Nothing to worry about though, a bit of heat and the hinging process will sort that out.  The laminated elevons are amazingly stiff, certainly comparable to a half decent chunk of balsa that hasn't been covered, so I have no worries about using these on a fast FPV machine.

As the iron was warm, I laminated a pair of wings too.  These were wrapped around the leading edge so the seam was at the trailing edge.  The width of the film wasn't quite wide enough to cover the entire wing in one piece, so I figured I would rather have the join running chordwise.  The wingtip was a bit tricky as there is a little flange for supporting the tip fins.  Again, the addition of the laminating film increased the weight by a few grams, but vastly increased the torsional rigidity of the wing panels.  For a fast FPV ship, it is a great addition.  For my mapping ship, I shall probably just run a 6" strip along the leading edge of the wing to save a few grams.

Mr Postman also came whilst I was away, with a new v2 gps, an airspeed sensor and an alerter module for my Vector.  I think I'll mount the pitot tube at the join between the fuselage and the wing, in a removable housing.  I'm wary of it catching in transport and general use, so this seems to be reasonably well protected.  I did think about putting it in the nose for the cleanest airflow, but this is just asking for damage (Both in transit, and on landing!)

Next job is to get some elevons hinged, control horns and servos/linkages sorted.
Title: Re: Andy's Drak
Post by: Andy Sayle on February 24, 2016, 10:04:35 AM
Not too much done last night, I got distracted refurbing my TBS Caipririiiiininnininha ready for some possibly nice weather this weekend.  I ran the servos on a sweep test for 10 min to burn them in (I always do this to check they don't go pop, or have any other problems.  The last thing you want is a duff servo that you have just installed).  I'm using Hitec HS5665MH servos.  Overkill for this plane, but they are reasonably priced, perform well, and can operate directly off a 2s lipo if needed.  Part of me is contemplating running the electronics off a separate battery pack.

I installed the servos in the wing using a smallish dab of hot glue.  The pockets were relieved for the lugs on the servo (I did wonder about cutting them off, but that's just adding work for myself) and a clearance hole/channel cut for the wire.  I also found I needed to chamfer the edge of the bay to allow the servo to obtain the maximum throw.  The hotglue works well here as it can be pulled out using a bit of alcohol to loosen the bond.  Perfect if a servo ever needs replacing.  I also started the control links.  I'm using Robart 1" bolt through horns.  These are nice and robust, have a three bolt through design that will clear the elevon sparring, and also have an integrated ball where the clevis is installed.  This will alleviate any bending in the control link, due to the misalignment of the hinge and control link.  The control links are 3mm solid carbon rod, with m2 ends bonded on with some Loctite gel CA.  I've only glued one end, as the other needs to be trimmed to size once the horns are installed.

It was at this point I realised I need to have covered the elevons before installing the horns.  I'm still undecided on the colour scheme, so onto the cairprprprriiriirnha it was.  I can't decide whether to use a bit of profilm on the elevon (Black) and do a fluorescent green leading edge, or whether to take a leaf out of Mutley's build, and use some fancy printed vinyl all over.  Obviously in a different pattern though!  And there is a roll of rather nice carbon effect vinyl sat in the corner of the workshop too...  bit heavy that mind...

I'll ponder that at work today....
Title: Re: Andy's Drak
Post by: Andy Sayle on February 25, 2016, 12:52:23 PM
Just a quick 30 min on the Drak last night.  I started off the electronics install properly.  First up was the Pitot tube.  I've decided to mount this at the join between the fuselage and wing panel.  So I melted out a channel in the root of the fuselage to drop the tube in, and then melted some channels for the tubing that go back to the saddle bay.  This will allow the tubes to be taped in place (maybe with a dab of hot glue too) for easy replacement.  The sensor will be mounted in the saddle bay, and the Vector bus cable routed back in the main bay alongside the servo extension.

I then thought I better update the firmware on the vector and check it works, but I had a little issue.  I don't know if it was my heavy handedness, or a fault in the products, but when I removed the cables from the GPS v2 unit, and pitot sensor, the cables took the outer connecter shells from the sensors with them.  Not ideal really, so I've pinged a support email off to RC-Log (where they were bought from) to see what they recommend.  I reckon I can probably get the shells back in place, and maybe put a dab of adhesive to stop them coming loose...

Still no decision on the colour scheme.  Anyone know of any good printed vinyl suppliers (Not really heavy vinyl either, nice light stuff please!)?  I also can't decide whether to have a go at laminating the fuselage.  I want to, but the complex curves, and high chance of me ending up with a wrinkly mess is putting me off...
Title: Re: Andy's Drak
Post by: Andy Sayle on March 14, 2016, 11:52:08 PM
The build has been on hold for a short while, other things getting in the way of building time.  I'm still no closer to a colour scheme, so I'm going to have a crack at laminatification on the fuselage, and go from there.  I can always put some decorative vinyl on at a later date..

Andy
Title: Re: Andy's Drak
Post by: mutley2 on March 15, 2016, 11:42:09 AM
Hey Andy, I think Lam is the way to go but the part where the wing joins the fuzz is a real 3d shape and needs to be thought out, I used some thin lam I had from the Z3 build and it turned out ok but was hard work. I also went for the Ritewing balsa control surfaces, top grade balsa and worth the few quid extra IMo.
Keep the build pic's coming  :D
Title: Re: Andy's Drak
Post by: Andy Sayle on March 15, 2016, 11:46:48 AM
I'm going to get the flight controller and electronics installed for now.  I only have the fairly thick laminate that came with the Drak kits, what thickness is the Z3 stuff?  Any ideas of a UK supplier?

I think I'll use the thicker lam on the underside, that is going to take a beating on some of the rocky sites I have planned to fly from!

Cheers
Andy
Title: Re: Andy's Drak
Post by: Billy_boy_2010 on March 16, 2016, 12:19:39 AM
I would always always lam something which I wanted to last. I bought some lam from flying wings. They had two levels of thickness which should suit you. I suspect both are thinner than the Ritewing stuff though.

People spend far too long on the appearance of their planes IMO. I wouldn't get obsessed about colour. Having said that- I'm going to iron some ooracover onto my wing post lam which should prove pretty quick and easy im hoping!
Title: Re: Andy's Drak
Post by: mutley2 on April 02, 2016, 07:44:36 PM
Hey Andy, what batteries are you going to use?
Title: Re: Andy's Drak
Post by: Dave G on April 03, 2016, 09:39:48 AM
Hi Andy, I notice your servo leads have a nice twist in them, did they come like that or did you do it?
Title: Re: Andy's Drak
Post by: Billy_boy_2010 on April 03, 2016, 01:10:32 PM
Quote from: Dave G on April 03, 2016, 09:39:48 AM
Hi Andy, I notice your servo leads have a nice twist in them, did they come like that or did you do it?

Use an electric drill and it's a doddle.
Title: Re: Andy's Drak
Post by: Andy Sayle on April 03, 2016, 09:26:35 PM
The servo wire was twisted when I bought it, this is the stuff I use:  http://www.componentshop.co.uk/3-way-heavy-duty-hitec-jr-twisted-servo-wire-20-awg.html (http://www.componentshop.co.uk/3-way-heavy-duty-hitec-jr-twisted-servo-wire-20-awg.html)   I have twisted the wires myself in the past too, using a drill and that works good too.

Battery wise, one of the Drak's will have the Ritewing SS motor, and a 5s setup.  I'll start with a 5000mAh pack for the maiden to keep the weight down a little (unless I need some more weight in the nose!) As for the other one, I'm not sure yet.  I'll see how the first flys, before deciding on a motor/batt combo.  I'll lean towards a 6s setup for that one though, mainly because I already have a lot of 3s and 6s packs I can use..

I should really get back on to this build, i got distracted by some little quads!

Andy
Title: Re: Andy's Drak
Post by: Dave G on April 07, 2016, 09:36:36 AM
Quote from: Billy_boy_2010 on April 03, 2016, 01:10:32 PM
Use an electric drill and it's a doddle.

Really! a drill - you and Andy do this, could you let me know how?  :o
Title: Re: Andy's Drak
Post by: Andy Sayle on April 07, 2016, 10:06:24 AM
It's easy.

Get tour untwisted servo lead, or separate wires and hold one end of then in a vice, or pin them tightly to a workbench to stop the end flapping about.  With the other end(s)  clamp them together in the chuck of your drill.

Now hold the wire(s) fairly taut,  and set the drill going to wind it up.  Start slowly, and don't over twist them.  Whilst you need to hold the wires quite tight,  be aware the wire length will shorten as you twist.  The last thing you want is a load of broken wire from over twisting and over tensioning.

Once you have the desired twistyness you need to hold it for a few seconds.   Then unclamp the wires from the drill chuck, and be reAdy for them to unwind a bit.  Then you are done!

I normally do them in 5 or 10 metre lengths, and wind it onto a reel to store...

Hth.
Andy
Title: Re: Andy's Drak
Post by: Dave G on April 08, 2016, 08:46:31 AM
Quote from: Andy Sayle on April 07, 2016, 10:06:24 AM
It's easy.

Get tour untwisted servo lead, or separate wires and hold one end of then in a vice, or pin them tightly to a workbench to stop the end flapping about.  With the other end(s)  clamp them together in the chuck of your drill.

Now hold the wire(s) fairly taut,  and set the drill going to wind it up.  Start slowly, and don't over twist them.  Whilst you need to hold the wires quite tight,  be aware the wire length will shorten as you twist.  The last thing you want is a load of broken wire from over twisting and over tensioning.

Once you have the desired twistyness you need to hold it for a few seconds.   Then unclamp the wires from the drill chuck, and be reAdy for them to unwind a bit.  Then you are done!

I normally do them in 5 or 10 metre lengths, and wind it onto a reel to store...

Hth.
Andy

Thanks very much  :D
Title: Re: Andy's Drak
Post by: Andy Sayle on May 04, 2016, 01:36:39 PM
Time is marching on, and I haven't finished my Drak yet!  So last night, I hinged the elevons, and started on the control rods too.

I decided to use some trusty diamond tape to do the hinges.  I used the "overunder" type hinge where two pieces of tape about an inch and half long are taped together (adhesive side to adhesive side) with about 5mm overlap.  One side goes on the top of the elevon, and the other side goes on the underside of the wing.  The next one goes on top of the wing, and under the elevon, and the third one goes on top of the elevon and under the wing.

I did three sets of three tape hinges, one at each end of the elevon, and one in the middle.  This gives a completely free hinge, that is held in the right place really tightly.  Obviously taking pictures of some crystal clear tape on a grey background is next to impossible.

Oh, and I gap sealed the hingeline with a length of diamond tape running along the top of the hinge, and a length running underneath the hinge.  This does reduce the movement a little, but I don't think the Drak will need 3D style throws anyway.

Next up, I fitted some rather snazzy robart control horns.  These are moulded plastic with a built in ball.  They bolt through the elevon (over the spars in there) and the ball takes out the twisty action due to the control rod not being at 90° to the hingeline.

The next job is to find the neutral angle for the elevon (I think Mr Ritewing has a jig for printing somewhere in internet land), and trim the control rods to length to fit the servo end clevis.

I've still not decided on covering/colourscheme too!  Sod it, I'll press on and sort it out later...
Title: Re: Andy's Drak
Post by: Andy Sayle on May 05, 2016, 11:24:50 AM
Another hour or so on the Drak last night.  This time I've finished the control rods off.  I cut the carbon rod to size, and glued the clevis adapter thing on with some CA.  Just the ticket.  With the 1.25" robart horns on the control surface, and the clevis on the inner servo horn hole, I can get around 25mm movement each way on the elevon.  That should be plenty I think.

Next up, was the fuselage.  I've decided to not bother laminating it.  It feels really sturdy, and some grass stains won't look too out of place from landing!  I may change my mind and out a strip of lam on the underside though, we shall see.

So, I've mounted the Vector, ESC, airspeed pitot thing, GPS/mag sensor, and tucked the wires down as neat as I can get them.  Hot glue worked wonders here!  I've also fitted a Jeti Duplex rx for now.  I'll do some LOS test flights, and vector tuning, before swapping the RX out for a TBS crossfire beastie.

I've also bonded the correx saddle bays in place with some goop.  A knife slit through one half makes a really nice hinge for access.

The next job is to get a little FPV cam mounted in the nose, wire that in with a VTX up front too, and then assemble the beast to see where the batteries need to be located to hit the correct CG.  If all goes well, I should be up for a test flight next week at some point!

Andy
Title: Re: Andy's Drak
Post by: Coyote on May 05, 2016, 09:03:07 PM
They really are that massive that the kit you put in it looks completely lost in space :)

Looking forward to seeing how you get on with the maiden.
Title: Re: Andy's Drak
Post by: Andy Sayle on May 05, 2016, 11:25:54 PM
They are almost too big to be honest.  There is so much room to mount stuff, it makes deciding where to put it all a nightmare!

I've been reading up in how to work a Vector this evening.  Think I've got the general gist of it. I'm planning in starting out with a LOS flight with no assistance at all, and then switch in stuff to try it out...

I need to buy some more 5s batteries too.  Only got one 5000mah pack at the moment...
Title: Andy's Drak
Post by: Ritewing on May 07, 2016, 08:49:48 AM
Here is a good maiden vid. Enjoy!  https://youtu.be/yYwAzLVuVPQ

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