Scale Soaring UK

This is from the Mike Trew plan, a 1/5 scale 118" span model of the French 50's sailplane and, apart from an aborted similar scale Minimoa from many years ago, will be my first scale glider traditional build.

The plan has been acquired from Sarik and extensively studied in order to formulate a build method, materials needed and what changes to Mike Trew's original design may be desirable. First decision was to go with a different wing section and a PDF file was kindly supplied by Peter Balcombe with the HQ rib profiles, so I should end up with a more versatile model. The pushrod activating the ruddervators will be dropped in favour of mini/micro servos, the ailerons and brakes will be wing mounted servos.

Decisions still to be made:
Colour scheme: although this can wait until later it will have some bearing on how I cover/finish the model. At the moment I'm leaning towards glassing the fuselage and filming the wings/tail surfaces.

Wing joiner: the plan shows a traditional brass box/steel blade arrangement, I will probably go with this as I can get the parts and it's what I'm familiar with.

Brakes: I probably won't do the scale blades (scale police look away now), they look like a lot of work that could be easily wiped away on a slope side landing so will either go commercial or "barn door" type diy.

I intend to fit a tow release and instead of balsa I will manufacture the nose from car body filler, this will add a lot of ding resistance and weight where it's needed.

The back end is known to be vulnerable so needs beefing up, first thought on this would be to replace the 1/8" x 1/8" top spruce longeron with a 1/8" x 1/4". Any ideas on this would be welcome! The wood is on it's way from SLEC and today I made this: 2 metres long so should be future proof

All being well I can make a start on cutting out parts next week ...............

Good work Stephen.
You went for the Bridson jig after all then

Thank you Peter, yes it made sense - re-usable/adjustable and super accurate, what a clever idea and I'm looking forward to it's maiden build!

Stephen,
Hope I’m not teaching you how to suck eggs, but:
Mark a fuselage datum line on all formers once cut & use your jig to hold each former at correct height & station via uprights on your jig brackets - datum marks should all be a the same height on each side of the Fuz.
You will be able to check fuselage straightness by eyeing from front along top spine slot to check everything stays in line.
Probably a good idea to add longerons on each side in left/right pairs to even out bending/twisting forces (steam longerons if necessary).
Once top half of the fuselage is planked, it should be rigid enough to hold its shape once taken off the jig in order to do the lower half.
Peter

Thanks Peter, I'm eager and grateful for any advice I can get as this is my first "jig" build. What are your thoughts re. increasing the depth of the top longeron to strengthen the rear of the fus (I'm mindful of previous comments regarding the weakness in this area)?

Stephen,
I will have a look at the plan, but from what I remember, the main issue around the rear of the fuselage is that given that there are two largish holes in the fuselage planking where the tailplanes fit in, there isn’t much to prevent the fuselage failing at the point immediately in front of the tailplanes.
Given that you are not planning to need ruddervator pushrods going through this area - just two servo cables, I would suggest some internal strengthening (without adding much weight) from say the former in front of the one where the tailplane LE connects, to the rear former (where the rear of the tailplanes are secured).
(I made the rearmost former (or certainly reinforced it) with a former made from 1/16” thick epoxy board, particularly as it had the screw threads poking out of it to secure the tailplane halves)
I found that if the model went over onto its back for any reason, the fuselage broke off just in front of the tailplanes!

I am glad to see you have made a start Stephen. I am also glad to see you have made a "Robbie Jig". I made one many years ago and have used it to build at least 5 very straight gliders since then. I will watch your build with interest.
Brian.

A large stock of wood arrived from SLEC a few days ago leaving me little excuse not to get started. The jig is fully up and running with former supports now added:
First job was to christen the Dremel and make a start on the forward 3mm ply formers, I soon realised that this wasn't going to be a quick job with the fuselage being round, not to mention the constant in/out of the Dremel blade (which is a fiddle) to facilitate cutting inside:
After the 3mm formers are complete I then have to cut the rear formers from 1/16" ply and laminate to 1/16" balsa, at that point I should be able to start jigging up and getting the glue out.

Apologies for off topic - nice to see the Moulton in the workshop

paulj wrote: ↑31 Jan 2019, 18:30 Apologies for off topic - nice to see the Moulton in the workshop

Well spotted! There's also a TSR30 hanging just above the TSR27.

A little bit more progress, the ply formers are all cut and I started to cut the corresponding 1/16" balsa formers indivdually before realisng it was a mugs game, so glued the ply direct to a sheet of balsa and then clamped them up to dry overnight:


I then produced a spliced join on the spruce longerons, not easy on 1/8" x 1/4" material, something a bandsaw probably would have handled better than my Dremel. In the end I found the best and most accurate method was to use the coarse side of my perma-grit to bevel each piece. PVA and clamped overnight:


Then on to cutting out the ribs for the ruddervators, I was surprised how tiny they looked - I think these will be quite delicate when finished with just a balsa leading edge and spruce trailing edge to add:

Going ok then Stephen.
I used a razor saw to cut the strips for my splices, but whatever method works for you.

Stephen, I agree that the razor saw is a good way of cutting strip wood splices. I have a series of fine to coarse blades for different materials. I have found the painful lesson in the damage these blades can do to fingers if you lose control. Regards John.

I tend to agree with all the comments as I have yet to find the perfect splicing method. Its impossible to get a good splice cut with my Dremmel jig saw or even with my razor saws. Also the longer the splice the harder it becomes.
My fall back method is to roughly angle cut the spars with the Dremmel then after clamping one cut on top of the other sand them together with my perma-grit block. This is not perfect but does give a fairly good fit.
Brian.

60 grit disc on a disc sander works wonders...

Have used my router mounted upside down in the workmate and screwed temporary angle iron fence at the required taper angle to the top.
Works for me, just mind your fingers though.

John M

A bit more progress, the tailplane ribs were produced using the sandwich method so should soon be able to put the empennage together:


Now gettiing close to assembling/glueing the fuselage together, I tried a dry fit on the jig to make sure everything went together or needed some final fettling:


I might have erred in producing former supports that are too simplistic, I have marked the datum line on all the formers which gives me a horizontal reference point but I'm finding it a lot of faff to measure up from each side to level them, unclamping and re-clamping is not the most precise method of adjustment. I notice that others have produced T shaped supports with a horizonal bar extending outside of the former. I have thought of making a new set of supports but I'd like to avoid that if possible so I'll have another jiggle around tomorrow and see if I can crack it with the set up I have.

On a more positive note, I went shopping this morning and came back with a piece of plasterboard ideally sized at 2M x 600mm for building the wing on. I say wing as there is only one on the plan, any suggestions for the easiest/quickest method of producing the second one?

Stephen,
Also possible to trace the important lines on the rear of the plan sheet if you temporarily tape the plan to a large window/patio door pane (printed side to glass).
The rear illumination then shows up all of the print on the reverse side

StephenB wrote: ↑04 Feb 2019, 18:18 '.................I might have erred in producing former supports that are too simplistic, I have marked the datum line on all the formers which gives me a horizontal reference point but I'm finding it a lot of faff to measure up from each side to level them, unclamping and re-clamping is not the most precise method of adjustment. I notice that others have produced T shaped supports with a horizonal bar extending outside of the former. I have thought of making a new set of supports but I'd like to avoid that if possible so I'll have another jiggle around tomorrow and see if I can crack it with the set up I have.

On a more positive note, I went shopping this morning and came back with a piece of plasterboard ideally sized at 2M x 600mm for building the wing on. I say wing as there is only one on the plan, any suggestions for the easiest/quickest method of producing the second one?'

Stephen,

The jig adaptor plates are ok, just need a bit of fine tuning and a better way of clamping the formers to them.
Make sure each plate is in contact with the jig base once secured to the ali angle - that way they can't rock from side to side.

Also, I never found those spring clamps, even heavy duty ones really satisfactory for this job - proper mini g-clamps are much better, done up really tight and preferably one each side when you are at the early stages of construction when you are struggling getting longerons to fit.

Robbie, thanks for the comment and the photo.

I know what you mean about the spring clamps - I'm reluctant to go to anything bigger as they will crush the balsa on my ply/balsa laminate formers, getting G-clamps in might be problematical as the gap between my formers is quite narrow compared to your fuselage (65mm at worst). Although I notice on yours you haven't clamped each former??

Ah, I missed the ply/balsa laminate bit.

You could always put a drop of thin cyno onto the former/support mating faces - both sides once you have them lined up correctly. Separating them later will be easy enough with a razor saw or good blade. That, together with the clamps should hold them fast. Just make sure you put the cyno where you can get at it later with the razor saw.

Some of the clamps have probably been removed in that photo to be used for something else. I normally clamp each one but don't necessarily support every former:


I used 'T' type supports on the M100 around the three main wing mounting formers to position the main longerons accurately as they were the fuselage datum.

Robbie is right (once again). Once the bottom longeron is in place on the supports a little spot of cyano between the support and the former lends security when they are clamped up. If you check out my Skylark 4 build - on page 2 there are several photos of my jig and clamp setup. It is definitely fiddly at 1/5 scale but it can be done.
Brian.

Thanks chaps, that's a very good tip re. the cyano to hold the formers in place.

I spent the afternoon getting everything aligned using a straight edge clamped to a builders square that I could move down the line of formers setting the datum on each one. I've dry fitted all the longerons and keel so feel confident I can move on to glueing it up.

Yes Brian it is fiddly and I'm also very conscious of how delicate a structure this is, a consequence of the 1/5 scale I guess, I'll feel a lot happier when it's sheeted up!

A little more progress, slow but steady, I'm finding this quite a tricky build possibly due to the scale, Mike Trew has I think designed it to be a light build which makes for a delicate structure - the elevators particularly so. Also I'm having to do a lot of "fettling" where parts are not matching up too well, the plan is very heavily drawn and a bit "furry" so transfering to photocopier and then to wood before being subjected to my "Dremeling" skills leaves me with a heavy filing and sanding workload!

Anyway the fuselage is now glued up and appears to be un-banana like, so far so good:

Before I can do much more work on the fus I need to have some flying surfaces to hand, so next job was the tailplane and ruddervators, a micro servo installed in each half, set-up a V-tail program on my Taranis to make sure all was working correctly before skinning:

Then on with the open structure ruddervators:

Soft balsa tips were added and the mounting hardware fabricated from 1.5mm aluminium sheet:

Final job today was to add the spruce angled cockpit longerons/canopy support:

It’s coming on well Stephen

Good progress! I don't know why you feel that you are going slowly - some of our contributors take years to get that far, don't they Barry.
Brian.

Phew! That was a close one...................

A bit more action on the Fauvette front to report. The V-tail has been a long winded exercise with a lot of fiddling to get it set up correctly, the ruddervators are very delicate and don't take kindly to frequent handling/fettling so I was glad to finally get them covered:


The tailplane halves slot nicely onto the rear facing fixing bolts and are aligned with a single stud at the front, a tailcone sits here which is removeable on the original but as I have no linkages to connect I will bond it permanently in place:


I have gone as far as I can with the fuselage, wing joiner is dry fitted, cables are installed for the ruddervators, so before sheeting can commence I need to have the wings available.


Wing joiner boxes have been epoxied together, modified from the plan to allow for the shallower aerofoil:


Wings next and I need to make a decision on the brakes, I'll most likely install the pop-up "door" type (non scale of course) to simplify the build and make the model more prang resistant. If I aim to keep the same area of vane as the original scale brakes they come out at a size of 300mm x 30mm - does that seem sensible?

Wing ribs have been cut out after a false start whereby I realised half way through the starboard wing batch that my printer had produced them at it's default setting of 97%! Half a day and a bit of balsa wasted. Spruce spars and trailing edge spliced and all ready to go.

Dry fitted lower spar and ribs on the plan to check fit and now ready to start glueing up but I'm dithering over the build sequence which I think goes like this:

Glue ribs on to bottom main spar and lower aileron spruce spar, glue false leading edge and spruce trailing edge which will be packed up to suit.

Glue top balsa trailing edge in place, slot out root ribs and epoxy in place the wing joiner box, glue top main spar in place.

Webbing around the wing joiner box - epoxy in place at same time as the box goes in?

At around this point I need to remove the wing to get the bottom sheeting on but doubt it will be very stable so do I web the whole wing prior to removing and sheeting?

At which point should I seperate the aileron?

Stephen,

It is preferable to get to the stage where you can add the top sheeting - that obviously includes all the false LE stuff, webbing etc while the structure is still on the board. This ensures the spar remains straight and doesn't bend.

To do the bottom sheeting the wing will, of course, have to come off the board and you will probably be quite alarmed at how twisty is is. This is quite normal and will be remedied once the lower sheeting is added. To do this, the wing must be placed back on the board, upside down and the structure supported with the correct incidences while you add the lower sheeting so you don't introduce any adverse twist into the structure. You can either do this by making full profile supports for the appropriate positions or use a wedge system as I usually do as shown below - just make sure the blocks and wedges are well secured and don't move.

Once it is all dry the wing can finally be removed from the board.

It is of course, not actually necessary to buid a wing on a board at all:

Thanks Robbie. So, don't remove from the board untill the whole top surface is complete - sheeted, brakes installed, capping strips in place, leaving only the lower sheeting and cap strips to be fitted?

Then cut the aileron out?

Just the top sheeting and as much of the TE as you can do with the wing on the board. Don't start cutting out for brakes and stuff until the lower sheeting is fitted and the wing nice and torsionally rigid. Detail like cap strips can be left until the wing is off the board.

The important thing is to ensure the wing is well supported once you have turned it over to do the bottom sheeting - once that is added the relative incidences along the wing are more or less set in stone.

How are you going to glue the LE sheeting on?

I would normally use PVA for the sheeting, pinning and taping to hold it in place, although in this instance with a spruce false LE I may have to fit the balsa LE prior to sheeting to give me something to pin to.

I like to use CA for the cap strips as I can hold them to the curve of the rib for the few seconds it takes to set - quick and simple.

Stephen, to either glue down your leading edge sheeting with no false LE sheeting or the finished LE in place is not the best way to do it. You are likely to end up with wavy sheeting.
I would seriously consider a 1.5mm false LE glued on the nose of the ribs with the spruce reinforcing piece behind it. Sand the 1.5mm flush with the top of all the ribs and you are left with a nice straight gluing edge for the sheeting. You can then add the LE proper and plane and sand it to profile and the same to the underside of the wing when you turn it over. The LE proper doesn't need to be added until the wing is off the board with all sheeting added.

You can reduce the thickness of the LE by that extra 1.5mm if you want to but to be honest, I wouldn't bother (Scale Police alert!!!).

Stephen,
I can’t recall what I did with mine, but agree with Robbie.
The plan shows a Spruce horizontal dummy LE spar, so if you have fitted that, just add a vertical balsa dummy LE on the front & sand flush to tops of ribs to give a glueing land for your top sheeting.
Once top sheeting fitted, turn over, support & sand lower edge flush prior to fitting lower sheeting.
Once top & bottom sheeting fitted, you can cut/sand sheeting back to the balsa dummy LE & fit the real LE.
Plane/sand the LE to profile. I generally do this by eye, but you can also use cardboard/thin ply LE profile templates.

BTW, I tend to use Aliphatic glue wherever I might need to sand the joint as this dries hard & is better to sand than either Cyano (too hard) or white glue (too gooey).

Thank you Robbie and Peter, that makes sense and I'll proceed on that basis.

The onset of fine spring weather severeley cut in to my build schedule (such as it is) as attention was diverted to non-modelling jobs outside, but the nagging thought of a partially finished wing eventually lured me back in to the workshop.

Spruce false LE fitted:



Followed by the 1/16" upper trailing edege, and as advised I glued a 1/16" dummy leading edge on to the false LE to give the sheeting something to "land" on. The ply and balsa bracing was glued between the spars before the top surface sheeting was added along with cap strips:



The airbrake aperture was then cut out and blade fabricated along with it's fibreglass control horn before mouting the servo in the in the D box After running the cables and checking the operation the servo was hot glued in position prior to sealing up with the lower sheeting. Aileron servo was similarly mounted:


The underside was then sheeted, cap strips added, 3/16" sheet leading edge glued on and shaped before giving the near complete wing a sanding. Finally the ply root rib was fitted leaving only the wing tip to be shaped prior to glueing on, followed by the removal of the aileron.

Looking very nice Stephen

Yes, it is a bit of a b****r when life gets in the way of building but the model is coming along quite nicely Stephen.

Brian.

After a long period of idleness, summer diversions and a workshop reconfiguration it's back to the building board for wing number two!

Port wing traced on the back of the plan courtesy of a neighbours patio doors, ribs cut, spars spliced and dry fitted prior to glueing up. Starboard wing nearby as a reference as I've forgotten how I built it

Nice to see you back on track with this build Stephen. Nice workshop by the way - clean and tidy and easy to work in.
Brian.

Thanks Brian, I do like to be "organised" - I heard it rumoured that others hereabouts are like minded

That would be a certain Mr B Cole I suspect. Strange fellow - doesn't understand the concept of tidy.
Brian

I wonder if we could come up with a formula...i.e. The number of models produced per annum in direct relation to the tidiness of the workshop?

I have a feeling that I may be being got at, here.



BC

Could well be Barry, but I have a feeling it's like water off a ducks back

Geoff

Quack Quack

Chris, I think we could definitely come up with a relationship to the number of lost tools, servo arms, screws and other bits and pieces that inhabit the bench.
Barry, if it looks like a duck and quacks like a duck it probably is a ………….
Brian.

I find I'm spending most days in the workshop now in an effort to move the Breguet toward the finishing line. As ever some days are more productive than others, one day I'm steaming ahead and making swift progress, another day I'm wrestling with a myriad of fiddly jobs and rectifying silly mistakes!

I have completed the second wing, all that remains to be done on both wings is to cut out the aileron and fit the wing tips:



The wing root formers needed a bit of fiddling to get the joiner box and incidence tube accurately placed, these were then epoxied in place:



I realised at this point that I had made the mistake of glueing the incidence tubes in to the wings before lifting the wings off the plan, I couldn't get them to align properly so had to open up the sheeting dig them out, set them up accurately with the wings in place on the fus and re-fix everything. Finally all was ok and the wings fit nicely on the fus:

I've started on the planking/sheeting and the finished wings can be offered up to fabricate the wing root aperture and upper wing fairing which will support curved sheet balsa to blend the upper coaming in to the wing:

I've still to figure out how to blend the wing fairing, upper sheeting and reaar fusealge/tail boom together, once I've resolved that conundrum I can finish the upper planking and remove the fus from the jig. Now that really will feel like progress!

Bit the bullet and commenced work on the upper coaming, the plan suggests that this should be done in one piece of 1/8' balsa sheet, either side of the upper longeron. I first tried to gauge the shape I'd need to cut with paper, then moved on to a card template before trialling it with a piece of 1/16" balsa.



Despite soaking the 1/8" sheet in water I couldn't get it to follow the double curvature and the "flare" as it joins the wing root, so decided to tackle it in smaller pieces, 3" sheet wasn't wide enough to cover the depth of the coaming anyway so I had to continue with planking on the upper section. Doing it in bite size chunks got the job done fairly quickly, using cyano to help hold the curved sheet in place and bonding with PVA:




In between drying times I fashioned a ply nose former to carry the Hobby KIng sourced tow release:



Some cockpit detail has also been added:

Progress as of late has been lacklustre due to a bout of the dreaded man flu. Back on course now, finally the upper half of the fuselage sheeting is finished and the model has been removed from the jig:

A 3mm liteply tray has been fixed between formers F1 and F2, the upper half will carry the Rx battery and the lower half will have the tow release servo fitted to it:

Aileron carefully removed from the lefthand wing using razor saw and scalpel:

Starting to figure out the mechanics of the Frise ailerons, an aileron horn has been fashioned from Paxolin which will have it's connection point in the centre of the radius of the upper aileron spar, Robart hinge pins will be located behind the lower spar. It's all very tight in the aileron and wing trailing edge so careful and fiddly work is needed to stand some chance of getting smooth movement of the flying surface:

Looking very nice Stephen.
Best of luck with the Frise ailerons, but they do look very good when you get it working.
Peter

A little more progress on the "Warbler". The aileron for the right wing was sanded to profile, hinge points located and dry fitted to the wing. I couldn't arrange the internal mechanism to actuate the aileron so had to settle for an external pushrod connected to a fibreglass control horn - the space within the wing and the aileron wouldn't allow for enough of an angle to push the internal horn. But after a lot of effort it works and mimics the fullsize Frise aileron, the left hand aileron should be a lot quicker:



The servo was then hot glued in to position and closed off:



Blanks cut from hard balsa for the wing tips, I will probably glass and paint these:



Wheel fairing carved from soft balsa:



Tail cone carved from soft balsa, hollowed out and bonded to the rearmost Paxolin former using Pattex Stabilit Express:



And finally we have a pilot!

A bit more progress to report, tow release servo installed, connected and checked to be working. It failed after 30 minutes of running on the sevo tester so was replaced (Turnigy MG servo - good job I ordered two)!



The nose block slowly built up with hard balsa and roughly carved, fitting in weights wherever I can:



Finally the fuselage is completely planked:



Fully riggeed the airframe, and all the internal parts to get an idea of where the CoG is and how much lead I'm likely to need:



One last little job at the end of the day, Rx switch fixed behind instrument panel:

Is there going to be a hatch to replace the aero tow servo the next time it fails?

Tom Pack wrote: ↑20 Dec 2019, 02:48 Is there going to be a hatch to replace the aero tow servo the next time it fails?

No Tom, that's the first servo I've had fail on me in forty plus years so I'll trust that the curent rate of failure means I'm good for another forty years Same applies to my wing and rudder/elevator servos - they are all buried within the structure, worse case scenario I have to dig them out and make good.

I envisage flying this mainly from the slope anyway so the tow release I could live without if I had to.

I've covered the fuselage in 25gsm glass cloth and Eze-Kote, one application on to the bare wood, another to apply the cloth, sand back and then a final coat which was also sanded back with 500 grit to produce a nice smooth finish prior to painting. Whilst I accept it isn't as tough as epoxy I think for this application it will be fine and was very quick and easy to apply.

The cockpit interior has been painted out prior to fitting the "furniture":

And I've resolved the spring steel tailskid issue by making it from piano wire, bent in to a thin "U" shape and then formed to shape before epoxying in to a plywood mounting box (as per the full size). To make it appear solid I've simply covered it in heatshrink:

Steady progress, but with a lot of fiddly jobs and waiting for paint to dry it doesn't seem to amount to much.

Canopy frame roughed out from 3mm birch ply:

Finished to shape and size, corner fillets from glass cloth and epoxy prior to covering the inner surfaces in glass cloth and Eze-Kote:

Brass tubing added for scale canopy support and painting commenced:

Fuselage hung in the car port (good test of the nose release)! and primer applied, the paint finish is a rattle can job:

Good progress Stephen! This is the bit that seems to take ages - don't hurry it, enjoy the process and the finished model will look so much better. There is nothing wrong with rattle cans by the way - I use them all the time.
Brian.

Looking good

Starting to look like the finished article now:

Fuselage painted rattle can white and red:

Wheel fitted:

Tail end detail:

Canopy glued to frame and cockpit detailing finished:

Overall view of model, rigged to roughly ascertain CoG and estimate any additional nose weight needed:

It looks like I will be over the design weight, I estimate a finished AUW of 5lbs giving me a wing loading of 16.5 ozs sq. ft. but I'm hopeful that with the modified wing section she'll fly fine.

Looks lovely, Stephen...I shouldn't worry too much about the wing loading as the HQ section is generally very tolerant of the higher values...

chris williams wrote: ↑06 Feb 2020, 10:16 Looks lovely, Stephen...I shouldn't worry too much about the wing loading as the HQ section is generally very tolerant of the higher values...

Thanks Chris, I was hoping that would be the case with the wing section - it's nice to have a get out of jail card!

Looks gorgeous so far!!

D

Finally, it's finished!


Frise aileron:
Non-scale door type spoiler:
Canopy hinged to one side (scale) and secured with magnets on the other:
All graphics supplied by our very own Barry Cole:
With the CoG slightly forward of the position marked on the plan she comes in at a little under 5.5 lbs giving me a wing loading of a touch under 18ozs sq. ft.

Looks fantastic - well done!

Lovely, and super-light... Good luck with the maiden!

Very nice!

She looks very nice Stephen.
I’m sure the maiden will go well.

Congratulations, you have made a lovely job of the Fauvette. I hope you have a eventless maiden flight.
Brian.

Thanks all for the kind comments!

It may be a while before she flies as there are no slopes close to me and so the maiden will most likely have to wait until I next visit the UK, which is tentatively scheduled for September.

Still, that gives me time to build something else!

What a beauty, congrats on this build!!
Wish you lots of fun on the maiden!!

Daniel

Stunning work, cant wait to see the maiden video, congratulations on a lovely model, I have one in 1/3 and it's a lovely flying model that I hope to fly again very soon,.
Best of luck
Alexis Scott