Geoff's Tucano

[Geoff S]

After clearing up a few outstanding jobs and shaking off a bit of lethargy I'm actually starting my build. I'm using the CNC and wood pack for convenience and because I'm lazy. I've already bought my power system - an XYH 3542 1000 rpm/v motor coupled with a Black Magic 50 amp esc. I intend to adopt Phil Winks' removable wing because I think a 45" ws model with a glued on wing is going to be inconvenient both to store and transport. I also favour a firewall-mounted motor configuration mostly because it means the motor wires don't need to be fed from the front of the motor, past the spinning outer case, which always makes me nervous. I imagine the motor committing suicide by severing its own power source

I'm starting with the fuselage because I want to have that ready to fit the wing centre-section when the time comes. I've made a firewall to Phil's drawing and hit the first snag. It appears to be 3 mm too high. MY CNC cut fuselage is 67mm high at the front and the firewall is 70 mm. The distance from the bottom to the motor thrust line agrees with drawing (mine's the original from the May 2003 RCME). However the drawing measures 68 mm rather the 67 mm of the CNC fuselage side. Mind you when I was at work all drawings used to bear the legend 'Do Not Scale' (though most of my drawings were circuit diagrams) but aeromodellers have been ignoring that for ever and using drawings as jigs.

So, is the firewall deliberately proud of the top of the fuselage side, or do I trim it back? Not sure, I'll have to ask Phil what he intended.

Geoff

[WolstonFlyer]

Just posting on here to follow your thread

[Geoff S]

It seems there are a few discrepancies between drawings and the CNC cut parts. My original drawing from 2003 shows the front of the fuselage side as being 68mm high, the CNC cut part is actually 67mm and it seems that Phil's drawing is 70mm, hence the dimensions of his firewall. It looks like I'll be trimming the firewall Phil designed by 2mm at the top and 1mm at the bottom. I don't think this will affect the motor thrust line too much.

Something else to be aware of if you have the CNC pack. Former F2 is supplied as a solid piece. It needs to have hole(s) cut in it to allow access to the motor connections. I intend to cut a 30mm dia hole in the centre of mine. The need to cut access holes is written on the drawing but no holes are shown. Easy to forget and far easier to cut before glueing.

Welcome aboard, Wolston Flyer Not sure you'll learn much except what not to do. This is a model I've been intending to build since 2003 so you can see how keen I am!

Geoff

 

 

Edited By Geoff Sleath on 07/03/2013 19:52:24

[Geoff S]

This my first attempt at adding photos to the forum so I hope it works OK

A useful tool to aid building straight fuselages is the SLEC building jig and I've used it a lot but not for some time to a scratch build like this one. It's certainly easier to use if the formers interlock with the sides but, with patience, it works well with the Tucano.

Just two views of the sides with F2, F3 and the fin post ready to epoxy in position. I used Grip 1 hour epoxy because it gives lots of time to adjust parts and is very strong once hardened. Takes a lot longer than an hour to cure, I find.

It's probably not obvious but the gaps to fit the firewall are offset by 2mm to allow for the right thrust without using spacer washers which I find to be a bit fiddly. It's always an option to use washers to fine-tune the thrust if it becomes necessary. To aid alignment I also marked the centre of the formers.

The firewall will be added later but before I draw in the side to the curve of the formers - a lot easier job using the jig. It will need some shaping at the top to fit the curve. I will be using the 3mm ply motor mount supplied in the CNC cut parts at the front but I've cut a large hole in it with a hole saw. Also cut a large hole in F2 for motor access.

Geoff

[Geoff S]

I think it was Phil Winks who pointed out that the fuselage drawing was wrong behind the cockpit and the side was shown 10mm deeper than it should have been. I was tempted to cut my CNC cut sides down before commencing construction but decided to see how it was once the top had been drawn in. I though some of the extra would be lost in the curve.

That has proved to be the case in part but there's still about 5mm too much. I've corrected this not by cutting some off but by adding 5mm. There's plenty of wood left to cut a 5mm strip long enough to glue to the sides. I've done that and intend to glue the triangular section to the inside without needing to flatted one corner as shown in the original design. There's a bit more wood but most of it will be carved away in the shaping process.

I suspect Nigel adopted the structure so that he could make the sides from a standard piece of 4" (100mm) balsa sheet. The CNC cut sides are made from sheets stuck together to make them wider.

Geoff

[Geoff S]

First, the scheme for adding 5mm to the fuselage sides aft of the cockpit and fitting the triangular stock inside rather than on the edge seems to have worked out OK. I did that and glued the soft 10mm sheet on top and carved it to shape. Incidentally it necessitated a thorough sweeping of the floor afterwards to avoid treading dust/shavings out into the lounge (my workshop is an extension that opens off the lounge in our 19th century cottage) to avoid conflict with SWMBO . The angle just forward of the fin seems to be just about spot-on for the fin extension to mate up accurately.

Second, I've fitted the motor. It's an XYH 3542 which is identiacl I think to the Turnigy and other 3542. I'm pretty sure XYH make them all and the rest are badged by the various companies. I set the firewall 38mm back on the right (starboard) side and 36mm back on the left (port) side to allow for the right thrust. This is too far back. The drawing shows a 10mm deep collar on the front of the original nose engine mount but I can only get about 5mm before it would foul the back of the spinner. So, if you're using a similar motor then the firewall should be nearer to the front by about 5mm (31 and 33mm from the front of the fuselage side). I'm not going to change mine. I'll just put up with a shallower spacer ring.

Third, I'm glueing the wing sections together using my Fuselage jig as a sort of sash cramp. I think it's successful - I haven't removed them yet. As I'm having a removable wing I've cut the main (centre) part of the wing to 18" ie cut a 36" length of 100 x 10 mm balsa exactly in half. (How I wish everything was measured in metric units 1.5mm =1/16"; 3mm = 1/8" etc is only approximate and the little errors add up) The centre section will be 77mm and square (ie not profiled) so the wing will be in 3 pieces before being joined with the dihedral braces - see Phil Winks' drawings.

So some progress today while SWMBO went out cycling and did about 120km in the drizzle.

Geoff

[Geoff S]

The shaped turtle deck. You can see the 5mm strip added to the top of the CNC cut fuselage side.

The motor mounting showing the sidethrust angle built-in by angling the firewall. The spacer ring was made by cutting the larger diameter with a hole saw in my drill press. The centre hole is cut the same way but watch your fingers! I resorted to holding the balsa gently in a pair of slip joint pliers. Make sure the middle hole is big enough to get the motor through

The wing parts being glued together using the fuselage jig as a clamp. As you can see, I use Titebond

Geoff

[WolstonFlyer]

Looking really good Geoff,

I wish I had fancy tools like a drill press and building board with a jig, it took me over an hour earlier today to cut out a 3mm plywood F1 using a hand held fretsaw (I broke 2 nearly finished F1's in the process of cutting the centre hole... what fun)

I am using the Turnigy Propdrive 3542 motor and have got a similar position for the firewall, 39mm and 41mm back from the front of the balsa fuse sides, but I am using the 3mm F1 where it looks like you have used the 6mm CNC pack version. I think the Turnigy motor has a bit longer alloy prop driver because I will have room for a 10mm nose ring between F1 and the spinner.

 

Edited By WolstonFlyer on 10/03/2013 00:29:23

[Geoff S]

Well, Wolston, I've been collecting tools for about 60 years so I'm likely to have a few around. They last a long time and I, like my Dad was, am a bit of a tool junkie. Most of them were for working on motor cycles (one of my 21st birthday presents was a Britool socket set I still have) then for racing dinghy maintenance and then pedal cycles before I tried aeromodelling.

I'm not looking forward to carving the wing profile despite what Nigel says in his build article. That's tomorrow's job.

Geoff

[WolstonFlyer]

In that case I have plenty of time to collect tools but I will need a place to put them, my building bench is the kitchen table at the moment!

I have already shaped my wings and it was actually quite easy with a zip razor plane and sandpaper stuck to a bit of 2"x4" for a sanding block.

[Geoff S]

Well I've done my bit for entropy by creating copious amounts of balsa shaving and dust whilst carving the wings. Not as difficult as I feared but, like the proof of the pudding is in the eating so the proof of the wings will be in the flying.

For those using the CNC cut parts I suggest separating the ailerons from the trailing edge, cleaning off the burnt balsa from the laser cutting and tacking back in place with a few spots of Cyano to make the razor planing easier.

I've also made the wing dihedral braces. As you can see from the picture, I still have the centre section to make and then there're the torque rods and servo to fit. Not sure how I'm going to attach the wing. There's Phil Winks' method which seems to involve a lot of weighty 1.5mm ply but looks like it should work well and possibly provide the basis for a battery support. Then I'm considering 5mm bolts front and rear - 4 in all - without the usual dowel or ply tongue.

The width of the underside of the fuselage is adjustable to some extent because as it stands it's slightly concave but can easily be squeezed straight. Phil's mounting plate would certainly overcome that tiny difficulty.

This is my total progress so far.

Less progress tomorrow because I'm going helicoptering tomorrow morning - indoors and I'll take the opportunity to get the latest RCME and see what Nigel suggests. The trouble with being retired is that there aren't any holidays - 24/7 work

Geoff

[Geoff S]

Not much to show today. Before I can fashion the wing centre section and the canopy I need to have the fuselage outline straight so I've made a pair of 0.8mm ply doublers to fix inside the fuselage around the wing seat. It extends from F2 to F3. At the moment it's clamped by nearly every clamp I own whilst the Titebond goes off. I'll leave it until the morning.

I've started the canopy by cranking a piece of 3mm balsa for the floor. The join is a small piece of lightweight glass cloth and thin cyano. I've made a pair of balsa sides which will lift the bottom of the clear canopy higher at the back than the drawing shows but nearer to scale. I notice Nigel's finished models look closer to scale than his drawing so perhaps he did the same.

Mine will be launched using a dolly because I can't throw. I never could very well but a high spinal injury has made it much worse.

Geoff

[Geoff S]

My build is at the stage where lots of time seems to result in very little to show for the effort.

Before fitting the top and bottom of the front part of the fuselage it's better if the wing and cockpit are in place so I've been making the cockpit and joining the wing using Phil Winks' idea for it to be detachable.

I felt the rise of the bottom of the cockpit needed to be a bit more than on the drawing. I discarded the idea of adding to the fuselage side and went for the detachable cockpit side instead. Here's my cockpit base:

 

I made some 1.5mm plywood sides and glued them to the bottom so that they matched the fuselage width. Then I added balsa strips inside just a bit wider than the canopy is thick to form a slot to hold it. The only problem with this is that it reduces the space available for the Vortex cockpit interior so they needed to be trimmed as did the pilot's shoulders but the didn't complain and I hope it won't impair their flying skills!

I'm not a brilliant pilot painter but they don't look too bad from a few feet (like 100 ) I'm not too sure but I think they may be a female crew - hard to tell.

The transparent cover fits quite well without the need to glue so once it is glued it should be secure.

 

Still needs a little adjustment to make it fit the fuselage accurately but a Geoff bodge will sort that out. I intend to fix it with a wide plywood tongue at the front and magnets at the back. The plywood sides will hopefully make it less likely to be damaged in handling when changing batteries.

 

Despite lots of trial fits of the wing components, once the glue (Titebond aliphatic) was applied it was much more difficult - the braces are a tight fit in their grooves. I made the mistake of trying to glue the dihedral braces, both wings and the three centre section all in one go. I succeeded but it was touch and go because the glue was going off faster than I thought it would. Better to fit the braces into one side first, then add the main centre section piece between the braces and the other wing and leave the front and back centre pieces until last.

Here's the wing neatly fitted to the fuselage and it checks well for position.

 

 

The two short pieces at the inboard trailing edge are very vulnerable to damage; because of that and because I'll be belly landing I'll be adding an epoxy glass cloth layer over the bottom sheet.

Mounting will be 2 4mm nylon bolts. One at the front and one at the back. The square centre section in the fuselage will keep the wing in place.

Geoff

Edited By Geoff Sleath on 16/03/2013 20:08:28

[Geoff S]

Not very exciting but I thought it may interest a few to see how I've attached the wing.

This shows the attachment from above. Just a single 5mm x 25mm countersunk nylon bolt at the back and a 3mm ply plate at the front.

The underside of the attached wing. I've inserted a 1.5mm ply plate into the balsa to take the load and a threaded insert (available from Model Fixings) for the bolt.

The fuselage 3mm ply plate supported by a soft balsa 6x6 mm spar to give some glueing area.

The top of the wing showing the support tongue (full width to provide a good location) and an example of the flanged threaded insert. I think they make a much neater job than the more common 'T' nuts. They are also useful in ARTF assembly because they can be fitted from the front of (say) a firewall when access to the back may be very restricted.

I think a single bolt will be adequate. My Blizzard wing is held by single bolts front and rear and are quite highly stressed (the ply plate in the Tucano is as strong or stronger than a bolt) and my 84" 7kg Maher's Thunderbolt wings are held by 2 x 5mm nylon bolts and there's never been a problem in over 100 flights.

Geoff

[Geoff S]

Not much progress despite weather more conducive to building than flying. I've fitted the underwing sheet and glassed it with lightweight cloth and wing skinning epoxy. It needs a few more coats. I've epoxied and pinned all the hinges into the flying surfaces. I've fitted the aileron servo.

The last job was slicing off the leading edge and glueing hardwood strips on to give it a bit of ding-proofing. It would have much easier if I'd done it before joining the wings.

Next job is to fit the other 2 servos and install the push rods before enclosing the rear underside of the fuselage. Then all there is to do is finish carving the front top and bottom of the fuselage to shape. I intend to glass the underside of the fuselage as it'll be belly landing - lighter than an undercarriage, I guess. Then its covering and flying.

Geoff

[Stephen Wright 3]

Hi Geoff

Just stumbled across your posts over your larfs-being-had over the great Dubai Drone incident last month.

It is indeed Steve Wright that you interviewed all those years ago. I should stress that your contribution to my life and career was far greater than merely recommending me for the job

It would be excellent to communicate - T and I are no longer together, but still see each other regulary (she too still lives in Bristol), and I know that she would love to hear from you.

I am on steve dot wright at uwe dot ac dot uk.

Get in touch, and we'll geek out!

Best wishes

Steve

[Ian Jones]

Wow, I'm pleased to see that I'm not the only one to take years to finish my Tucano(s). One is glow powered and has actually flown but the inverted engine has flooding issues so I don't regard it as finished. The other is an a slope version which at about the same stage as yours.

So please don't rush yours, it saves me considerable embarrassment .

[Colin Leighfield]

Good stuff Geoff. I glued 6mm carbon fibre tubes onto the leading edges of mine for anti-ding and also to give a nice profile. Great model, although it is very semi-scale. The fuselage is shallower than the original and of course the wing taper is much reduced. It has already been found though that you can cut the wing taper to the scale shape without problems. Although it reduces the area slightly it is still ok and still no tip-stall tendencies, which seems to be a feature of the flat sheet wing. If I built another I would do this, although my original is still perfect exceot for needing a new motor.

[Phil Winks]

Hi Geoff nice work and I like the cockpit arrangement it should improve access to the interior somewhat, mine flew again at the weekend and is still a great model, I have uprated the power to 4s which required a smaller prop but nothing else, she is a bit faster but more importantly accelerates better with better vertical climb.

[Geoff S]

Trust Steve to pick the one thread of mine that ended in disaster!

My Tucano crashed on its maiden flight when I tried to take off with a dolly because I can't throw. I kept it for a while but eventually threw it away (too many models, too many models to build and a few needing a little TLC ) I had a lot better luck with the Ballerina which has been flown a lot and actually has an undercarriage.

I'll be in touch Steve though I wonder what horrors I inflicted on the world by recommending you as a graduate trainee all those years ago

Geoff