Topic: Sequoia Systems Greenfinch234 Build

Hello all,

This is my first build thread so please bare with me!! I've never found the motivation to do a build thread before but this kit goes WAY beyond what we are normally used to so I thought I'd do a thread as some of you might be interested in seeing how this bird goes together.

The kit is the Greenfinch Two Thirty Four from Sequoia Systems and I think it is something very special indeed. Granted nobody will call it cheap, but hopefully as the build progresses you will see just how amazing an achievement it really is. I've been building models for a long time and this kit is the first one ever that, so far, really seems to live up to what I've expected!!

Unfortunately the build had already progressed some way before I finally decided to do a thread but I did take some shots before I started so here they are to give you an idea.

Here's the box that she comes packaged in, don't know wether you can see with the small image but it is beautifully machined from MDF with knuckle joints on all edges and a three quarter view of the aircraft along with its name on the top.

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And here's what everything looks like out of the box.

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Again not sure you can see too much detail but believe me the quality of machining and wood selection is nothing short of breathtaking. Most of the parts come on varying thicknesses of birch ply and need to be seen to be believed, i'm told there are over 970 in total!! Also there are five booklets of instructions with HUNDREDS of photo's, and an A3 sized booklet of drawings, along with bags and bags of bolts screws etc and a bundle of carbon and aluminium rods, along with lenths of 2mm clear tubing, the use of which becomes quickly apparent. There is even a bottle of 'Superphatic' glue, a brush to spread it into joints and a syringe to wash out the steel application nozzle, here begins the feeling 'these guys have thought of everything!!'

Ok first post done!!

Back soon,

Greg

Ooooo, subscribed. This model looks a "fine art" masterpiece to combining art and science.

Please keep posting. 

I've drooled over these kits before, nice to see one going together. 

Paul

Ok here's where the fun begins!! The first batch of parts are cut from the sheets, I use my razor saw to part the holding tags followed by a quick swish with some sandpaper and hey presto, a part that would have taken me about three weeks to shape by hand!! It took me about twenty minutes to get this far, including joining the four parts that make up the fuselage sides.

I still can't believe how nice these parts are, straight from the sheet, so intricately designed and yet, because they are ply, you don't have to handle them like egg shells!! No laser burn on the edges either, Sequoia use their own design CNC routers and apparently they are more accurate than lasers. I believe them!!

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Construction begins quite conventionally with the forward fuse box structure coming together first. Where it's unconventional is that you don't need any glue yet, the parts slot together so accurately that you can pick this lot up by one of the formers and it doesn't fall apart!!

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You can't see it here but the firewall is laminated from two identical formers. How do you ensure they are aligned perfectly and stay that way while the glue dries? No need to worry they've thought of that! there are 2mm holes at opposite corners that the aforementioned 2mm plastic tube slots into. This is used to make little alignment pegs that holds the two formers perfectly in alignment while they bond together. It's little touches like this that start to make you think that this is something a little bit special!!

TTFN,

Greg

That looks so clean too, no wood dust. Can you build it indoors?

Are these very expensive?

Oh dear, sorry folks, thought I'd change the photo's for larger ones so you could see better but all I seem to have achieved is deleting them from the thread!! Mods is there any way I can put them back?

@Paul

Know what you mean, I drooled over the pics on the Sequoia website for about two months before I plucked up the courage to go for it. Glad I did!!

@Stueysheep

It is a very clean build and mine is going together on the kitchen table (understanding wife!!) however there is a bit of traditional balsa shaping such as the fillets between the fin and tailplane. I just take mine outside for the dusty stuff. This is minimal though and not nearly as messy as a normal build!

The kit IS expensive (£350 delivered) but I believe it to be very good value. Granted I could walk into my LMS and come out again five minutes later with a ready to fly aeroplane at about a fifth of that price, but that isn't what this is all about. If you just want an RC model that builds in the minimum time so you can get flying, this isn't the one. But if like me you enjoy building as much as flying then you will REALLY enjoy this one, the amount of hours of enjoyment I've had so far more than justify the price for me, and when you see the amount of work that Roger at Sequoia Must have put in to finish up with such a clever and intricate design, it is worth every penny. I'm sure loads of you will disagree but in my book you get what you pay for!!

@Stueysheep
  I'm sure loads of you will disagree but in my book you get what you pay for!!

I am with you here, worth every penny in enjoyment... A thing of beauty there...

Just hope you get over the problems with posting  so you can thrill us some more... 

Ok there's a bit of a jump forward here I'm afraid but you haven't missed much, here is the fuselage so far with the fin added, which is built in as the fuse progresses

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What is amazing is how straight and true this thing is with literally no effort on my part, it just goes together that way. I think this is indicative of how accurate the machining is. There is literally NO slop at all in the tabs that slot the thing together meaning it can't go together bent. My face is beginning to ache from the virtually permanent grin I seem to have these days!!

And another one from the underside

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Here you can see the two wing tongue boxes that take the epoxy glass wing tongues. Another clever little addition here is the two slots you can just see in the vertical faces of the forward box. when the wings are plugged in a carbon rod pushes into that slot and through a hole in the wing tongue. The carbon rods are then tensioned together with rubber bands so the wings can't come off in flight, but will in a crash. Ingenious, and all internal!! there is a pop-off ply hatch that allows access to this area when the model is finished.

In this shot, on the far side just behind the two hoop formers (the rear face of which will become the instrument panel, which I can't wait to show you!!) is the hatch release catch latch (easier typed than said!!)

If you look very closely in the centre of the cross member that sits about half way up the picture on the left, you can see a short length of the 2mm tubing that has been inserted through the two formers. Through this tube goes a 1mm pin that locks the forward hatch in position. As this pin exits the instrument panel it bends 88 degrees (not 90, 88 degrees!!) and latches in to the aforementioned catch. Another little touch that, while not strictly neccesary, I absolutley love!!

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Don't know why but I decided on building the rudder next, here are all the parts ready to go. Each one is machined with a slightly different end fitting so that you can't inadvertantly slot one into the wrong place.

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I didn't think it was possible to shape such small pieces in balsa with any degree of accuracy but they've managed it. When pressing the parts together, very little force is required and they sort of slide home with a very satisfying sssshhhhhh

And here it is about 30 seconds later, finished!! all it needs now is a brush of superphatic over the joints, which wicks in like CA, but leaves a small fillet like normal aliphatic.

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Hello all,

OK now on to hinging the rudder. The tail surfaces on the greenfinch are hinged in an unusual but clever way, our old friend the 2mm plastic tube is bonded in short lengths to both fin and rudder in an alternating pattern that eventually results in a kind of 'piano hinge' type setup.

Obviously to get a freely moving hinge these lengths of tube have to be in EXACT alignment and to this end Sequoia provide some birch ply jigs, with slots for the tubes which you can see fitted here.

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The plastic tubes are tack glued to the tail post, whereupon the jig can be removed and a fillet of 'RC Modellers Glue' (Good stuff if you've never tried it!) added to finally bond it

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This glue dries completely clear after about an hour and really does work, I was a little skeptical that these lengths of tube would be held on firmly enough to properly support a flying surface, but they certainly aren't going to fall off any time soon! Obviously the jig that fits on the rudder has slots in the alternate positions, and when the two are mated makes a lovely hinge.

Here is a shot of the finished hinge, not easy to see I know (my dodgy photography!) but there is a length of 1mm wire running up the middle, which will eventually be held captive by the tail wheel assembly. What this means of course is that the rudder, and all other flying surfaces are easily removable for covering/repair. Clever eh

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Nice kit of parts looks very good

I've been watching this with great interest. What a superb piece of engineering and well worth the money in my opinion. I would be interested to know the dimensions and finished weight of this one, also is it suitable for I.C or only electrickery. I did send an email to Sequoia Systems, but no reply so far. Can anyone supply these details because information on the website seems a bit sparse.
Regards,
Tentpeg. 

@Tentpeg.

Yes the model is suitable for i.c and the instructions go in to some detail if that option would be your choice. The model comes with a fully built up epoxy glass mount for electric motors but isn't supplied with a mount for an i.c powerplant. However the instructions do state that Sequoia  have that in hand and can supply a suitable mount.

If you go to the Sequoia Systems website and click on Models then Greenfinch234, all of the instructions are downloadable as pdf's. Every bit of info you could need is in there. Roger from Sequoia is watching this thread with some interest as you can imagine, he e-mailed me to say that he has received your e-mail and has replied, including the relevant info that you have requested. In case you still haven't received that the greenfinch is 34" span and is about 1 kilo all up.

Thanks Greg, I finally found all the details, I'm something of a dumbo navigating websites.
It's quite a bit smaller than I thought and about the smallest engine I have is an OS .30 four stroke. I wonder if that would fit inside the cowl? I'm certainly very tempted after looking through the construction sequence. Even the spats are a work of art in themselves!
I shall continue to watch your progress with great interest.
Thanks again.
Regards,
Tentpeg. 

@Tentpeg

I Spoke to Roger from Sequoia this afternoon and he said that yes, an O.S 30 Four stroke WILL fit within the cowl, he thinks it is probably the perfect powerplant in fact. He did say though, for anyone else that might be watching that a Saito 30 Four Stroke WON'T quite fit as the rocker covers are splayed.

He also said that they can supply a custom adapter for the exhaust on an O.S 30 that will line the muffler up beautifully with the underside of the aeroplane.

Roger is considering creating an account on here so that he can answer any questions like that, but until then he said please feel free to give him a bell. He is an extrememly affable chap and has bent over backwards on a couple of occasions to help me out, which is part of the reason I am so pleased to have taken the plunge and bought one of his kits.

Hope that helps,

Greg

Ok folks on to the tailwheel, here are all the parts cut from the epoxy glass sheet, again the old razor saw comes in handy here.

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I used thin cyano here as it's all i've got at the moment which is a little contradictory to the intsructions which specify thick.

However it worked fine and here you can see the finished article, minus the final paint finish of course.

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I was a little unsure if thin cyano would bond the epoxy glass strongly enough but it's definately not going anywhere!
 

Unbelievable!   

yum.... Happy Xmas to me.... 

@ Stueysheep,

You've put one on your letter to Santa then I guess!! 

Right back to the fuselage. There are two precut stringers that curve up either side of the fuse from the cockpit edges back to the fin fillet. They are installed at approx ninety degrees to one another and provide a shelf for the head rest fairing to mount to, as well as forming a nicely curved contour between the head rest fairing and the rounded area where the carbon stringers will fit later. Here's how it looks.

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Doesn't look like they form a very nice line where they terminate at the rear fillet but they aren't finished being shaped yet. Hopefully once that's done they'll flow together nicely.

The head rest fairing itself can be fitted now. They require damping with water to aid the curvature over the top of the formers. What I did here was to get them wet and then lay them damp side down on the board. I then put the handle of a wooden spoon on the back at the top end where the curve is tightest and gently lifted the bottom end until the curve started to form around the wooden spoon handle. one half fairing can then be glued on and I was pleased to see that it finished exactly on the centre line at the top. The other side was then added and only needed a whisker shaving off at the aft end to make it fit nicely.

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You can see I've also added the sheeting that forms the cockpit front edge, which has slots that take the windscreen posts. The sheeting projects past the formers all around the cockpit as this will be edged with some black rubber tubing after the fuz is covered to give a scale like look.

Now we need to fill up that big hole forward of the cockpit. The forward hatch fits here and is framed up from the following parts.

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The hatch slopes toward the nose and therefore the four formers are slightly different sizes. If you look closely you can see they have holes drilled in the top showing which one is which, i.e four holes for number four. Believe it or not I still managed to put them together the wrong way around!!

Fortunately I caught the mistake before i'd bonded it all together.

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There are two more formers in balsa, one each end that take up the last of the ply stringers, unfortunately this is when I realised that one of the balsa sheets was missing. 
however a quick e-mail to Roger at Sequoia saw a very embarrased reply and a new sheet on my doormat the following morning. Can't say fairer that that. 

Those new formers were then fitted and the skins after that.

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Uncle Ben helped me out here!!

Here's a shot of the hatch fitted in the front. It is held down at the front by the rear lip of the cowl, and at the back by the latch pin mentioned earlier.

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You can see that the former just in front of the hatch is canted forward. this allows the hatch to lift at the back in order that it can be removed to get the battery out. This is neccessary of course because the cabane struts will prevent it coming off sideways. Starting to get a hint of that classic biplane look now don't ya think?

Very nice. Just a shame that many can't be bothered with building these days. So much satisfaction!

That's just sooooooo sweet....

Wonder if they ever considered doing an 68" version?

Just what I was thinking, Stuey.
60 inch span or thereabouts would be better. 
It is a bit on the small side and with the eyesight getting weaker I'm wondering if I could keep up with it.
I would like to make one and leave all that beautiful structure visible by covering with clear solarfilm with just some minimal decoration.
Regards,
Tentpeg. 

Greg, have you seen this thread?

http://www.rcmf.co.uk/4um/index.php?topic=67740.0

Hello guys,

Tentpeg and Stueysheep, Don't tell anybody but I have it on good authority that the Greenfinch260 is well on the way , and may feature built up tail surfaces similar to the way the mainplanes are constructed on this one!!

Stueysheep, Yes I saw Profmb's thread before I bought my kit, love his colour scheme!! Apparently he has fitted a .26 four stroke and converted to petrol though it is down on power and he can't achieve better than a fast taxi at the mo. Don't know whether a prop change is all that's needed. Are you still out there Profmb? let us know how you're getting on.

Hi everyone,

Decided to do the cabane struts next, why, because they are ply parts that are faced with balsa, and that can't be done until.....
The upper centre section of wing is built!!

I've been saving the wings until last as I just know it's going to be my favourite part of the build but temptation got the better of me and anyway, why the hell not, It's my aeroplane!!

Here's the ply cores ready to go.

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These are simply bolted into the fuz with nuts and lock washers, with the bolt heads recessed into the fuz sides in pre cut holes.

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And here's how it looks now. The struts are straight at the moment but when bolted to the wing centre section form a gentle 'S' curve when viewed from the front. The balsa faces are then laminated on locking this shape in and forming a kind of 'spring', the tension of which keeps the centre section in the correct alignment.

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Ok so on to the centre section, here are some of the parts ready to go. Just look at those ribs!!

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The sixteen parts to the left of the shot make up the four wing tongue boxes that will take the exopy glass tongues from the upper mainplanes. I'll show you them later but the tongues have a hook on their inboard end that is restrained by rubber bands within a hatch in the centre section, again so the wings can fall off fairly easily in the event of a vertical landing!!

Here's what it looks like about five minutes later. Sorry about the dodgy photography again.

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What I just can't get across in words properly is how these parts go together. It is SUCH a pleasure when you slot them together and they fit SOOOOO precisely. I've never experienced anything like it before, especially from a kit. I've scratch built models before where I've been very pleased with my own handiwork but this degree of accuracy isn't possible by hand, especially on the scale to which this kit is working. That assembly above is only six inches across!!

Oh well there's a can of Fosters with my name on it in the fridge so I'll see you all later,

TTFN,

Greg

Hi Guys - Profmb here...Roger Moffat pointed me to this new thread.  It is really good to see Greg_S enjoying the build as much as I did. 

Thanks for sharing this build Greg.

Yes I have had a bit of a problem with mine for the reasons that Stuey states.  I have bought a larger (Graupner) prop and I am hoping that this does the trick.  My problem was that the engine was not delivering enough power. I converted the OS 26 to petrol using the Runtronics system from Weston.  The problem with this is that the sensor is so big relative to the crankcase that I cannot get the timing sufficiently advanced for max revs. Brian Winch has been a great help, and he uses the Rexcel Unit which has a much smaller sensor. 

However, I was not helped either by a naff prop that I bought with the engine.  Gordon Whitehead a mate of mine advised me to get a Graupner prop and we shall be trying this. Our efforts were also thwarted because the engine would not run consistently when in a nose up attitude.  I think that this has more to do with the fact that I need to change the clunk in what is a very small tank.  This I have now done.

Another concern I have had is the best place to locate the tank relative to the spray bar. I feel that it maybe either too high when mouted above the horizontal fomer or too low when mounted below it!  But test will prove this one way or the other.  So for those of you who have also completed an IC version it would be good to have your experience.

You might ask why this has all taken so long...well once I had finished this beauty, I then purchased the new Saito 30FG and put it into the Black Horse Ryan.  This is one hell of an engine - so sweet!  So I have spent a lot of time playing with this and flying the Ryan...to the detriment of the Greenfinch...or should I say the 'Goldfinch!'

Anyway sometime soon I hope to get it into the air...

Hi there Profmb, good to hear from you.

Sorry to hear you've had strife with you're engine. I think it will be well worth it in the long run though, with that lovely petrol engine sound!! keep at it!! Shame that lovely Saito won't quite fit in the front of the greenfinch!!

Love your colour scheme by the way . In fact it has set me to thinking because I was pretty dead set on a translucent livery in order to show off the structure beneath. However having seen your model I am now a little torn! I'm beginning to think, much like I imagine that you did, that those classic lines deserve a classic kind of paint job!

In fact I think it's worth putting out there, what do you guys all think, any suggestions?

As it's not a scale model, I don't think that it's important and is purely a matter of personal preference.
If I were to build one, and the construction had gone together well, without any ugly bits showing, I would be inclined to use some sort of covering that showed the structure off to its' best advantage. 
Best regards,
Tentpeg. 

Evening all!

Cheers Tentpeg, I hear what you're saying. I think I might sort of go half and half, maybe a sunburst on the wings over a translucent background, not sure which colours yet. Still there's no rush at the mo, lots of building to do before I get that far!!

Ok on with the centre section, by the way I think I've finally managed to suss how you can attach an image that gets bigger when you click on it

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You can see that the end ribs have been fitted and the wing tongue boxes made up. These slot in through the ribs and were too tight to begin with. However I think I might have been a little over zealous with the Superphatic on the outside faces and a bit of a sand on all four sides saw them installed with no probs.

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The wing tongue boxes protrude by a small amount outboard of the end rib and this is in order that the facing rib has something to locate to.

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On to the sheeting pieces and trailing edge infills next....

Heres how it looks with the four sheeting pieces added on the upper surface.

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The two forward pieces require the front edge chamfering to match the angle of the ply leading edge but other than that they need no shaping whatsoever.

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Hi y'all, probably about time I made my first post:

I was pretty dead set on a translucent livery in order to show off the structure beneath. However having seen your model I am now a little torn! - Greg_S

'As it's not a scale model, I don't think that it's important and is purely a matter of personal preference'  - Tentpeg

Yes, so the builder can relax and indulge his fancies, but it is also presented as a 'Could Be' scale model, with respect to it's detailing, and overall proportions, so in many respects it can look much more scale than many so-called scale models. Hence we have space for a full length pilot, and instruments that would actually have been used, (hope Greg agrees, I'm sure in his job he knows more about those than I do), and other details like the absence of plastic bits sticking out of control surfaces.

With regard to the covering, a possible compromise is to use Solartex on the fuselage and under-surfaces of the wing, and Vintage Solartex on the upper surfaces - Vintage is translucent and in a few primary colours, and there is also 'Antique', which is a see-through cream. In this way, the detail in the structure can be seen if you look closely enough, but at an angle the aircraft could still look as if it has had a coat of paint!

Greg - lovely job on the centre section - and on the whole model! Congrats on the expandable photos - how's it done?

Good to be in touch - Bye for now,

Roger

Now the cabane mounting lugs can be installed, here's how they look fresh from the sheet. There are four holes at the rear of each piece, this enables the builder to set the upper mainplane to four different incidences very simply (+1 to -2 degrees) Think I'll set mine at zero.

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And here's how they look in the wing. The screws are simply pushed through as they are intended as alignment pins not fasteners.

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I cheated here and used thin CA to bond them in. The instructions suggest epoxy, or at least thick CA. However with my experience of how the tail wheel components ended up so strong, and with the knowledge that there are screws through both mounting lugs and a rib I thought I could gert away with it. Now they're done, believe me they aint coming out ANY time soon!!

@Roger

You made it on here at last, it gets addictive be careful!!
Thanks for your advice and thanks for the compliments on the build On the photo's side I simply stopped making them SO small, the system seems to thumbnail them slightly when posted only to be revealed at their full size when clicked on. I'm pretty sure some of the other guys will know the correct method, indeed Profmb's pics are really small in the post and then really big when clicked on. Perhaps someone will let me know how that's done, I'd like to know because I guess It's frustrating fro people who'd like to see the real detail in some of the shots.

'There are four holes at the rear of each piece, this enables the builder to set the upper mainplane to four different incidences very simply (+1 to -2 degrees) Think I'll set mine at zero.' -  Greg_S

This is the incidence angle relative to the bottom wing, (which is set at +2degrees to the fus datum). Note the incidence line is from the centre of the t/e to the centre - most forward part - of the l/e.

Setting the upper wing at 0deg rel to the bottom wing gives very safe handling - providing the aircraft is not inverted! The upper wing tends to suppress the stall of the bottom wing, therefore the upper wing is likely to stall first, transferring flying loads to the lower wing which is further back, therefore making the ship nose heavy, so it drops it's nose and unstalls itself. Which is usually a good thing. However, it does make it difficult to get it to spin, which is also usually a good thing.

For spinning and general aeros, it's useful to set the upper wing to -1deg rel to the bottom wing, so that the upper wing stalls closer to the lower wing to give a cleaner entry into the spin - when right way up - (I think the full size Bucker Jungman was set up this way for the same reason). It also gives safer handling when inverted.
-2deg might be regarded as a 'super-flick' position, and isn't recommended - at least not until we've tried it!

Adjusting the upper wing incidence alters the length of the aileron link rods - and for that reason we supply parts for two sets of these, for those who would like to experiment.

Greg's choice of 0deg to start with is a good one, but don't get too slow when inverted ...

toodle pip - Roger