Middle Phase 2

[Mike T]

Posted by Jonathan M on 04/01/2018 20:02:42:

It strikes me that I am perhaps being a bit too detailed in documenting almost every step of this build?

Nope! It's all good...

Re the wingtips - just in case I'm reading you wrong, there should only be one layer of ply in the sandwich as this defines the centreline of the tip as well as the LE and TE. If you have more than one layer, it will introduce all sorts of problems with carving!

If you make the tip full chord, so you have an inset aileron, then the tip core must align with the TE of the aileron, so you must fix this in place temporarily (and properly aligned at the root as well) in order to determine the position of the tip's TE:

[Jonathan M]

Posted by Mike T on 05/01/2018 12:37:17:

Re the wingtips - just in case I'm reading you wrong, there should only be one layer of ply in the sandwich as this defines the centreline of the tip as well as the LE and TE. If you have more than one layer, it will introduce all sorts of problems with carving!

If you make the tip full chord, so you have an inset aileron, then the tip core must align with the TE of the aileron, so you must fix this in place temporarily (and properly aligned at the root as well) in order to determine the position of the tip's TE:

Cheers Mike - yes you're quite right! I've got a selection of thicker sheets with which to make up a single-decker sandwich with the ply as indicated in your diagram; and will pre-position the ply as suggested.

Thanks

Jon

[Steve Houghton 1]

Posted by Jonathan M on 04/01/2018 07:30:32:

Yesterday not a hugely productive day (some work stuff intruded, had to go food shopping, and the kid is ill with a persistent flu), but while the fuselage stuff was drying did some digging out of the wing aileron pockets.

The servos are an excellent fit into the inside slots of the covers, with very little slop, but I'll add servo-tape (or double-sided tape) on final installation to firm things up completely.

Edited By Jonathan M on 04/01/2018 07:38:32

With a foam wing, I tend to use the "potting method", whereby you wrap the servo in clingfilm or a thin plastic bag. You then smear the foam cavity you created with epoxy and micro balloons, (although the balloons aren't 100% necessary), then push the servo into the cavity and weigh it down so that it doesn't move. Once the epoxy has dried, you remove the servo and as much of the clingfilm as possible, then use a blob of hot melt glue to secure the servo in the cavity. This method stops the servo from moving about in the cavity as the foam has a tendency to give, especially over time.

An alternative to epoxy which I have used successfully is Gorilla Glue, the brown stuff that foams up. You dampen the foam with water first, (I use a spray bottle to do this), smear the cavity with the glue, then place your wrapped servo in the cavity, again weighing it down. As the glue dries it turns into a foam which fills every nook and cranny and then is really easy to trim with a blade. This glue is also perfect for gluing wing spars into foam too, but again you must weigh it down or the expanding foam will push the spar out of the slot.

[JACK]

l too have middle phase bought off fleabay,this is to be used to teach my son to fly,following which l will put together an aileron wing for it.....l fully agree with mg wing servos,also skinning with glass and epoxy will be of benefit,the design is plenty strong enough,build as per and you shouldnt have any probs...jack

[Jonathan M]

Posted by Steve Houghton 1 on 05/01/2018 14:39:14:

With a foam wing, I tend to use the "potting method", whereby you wrap the servo in clingfilm or a thin plastic bag. You then smear the foam cavity you created with epoxy and micro balloons, (although the balloons aren't 100% necessary), then push the servo into the cavity and weigh it down so that it doesn't move. Once the epoxy has dried, you remove the servo and as much of the clingfilm as possible, then use a blob of hot melt glue to secure the servo in the cavity. This method stops the servo from moving about in the cavity as the foam has a tendency to give, especially over time.

An alternative to epoxy which I have used successfully is Gorilla Glue, the brown stuff that foams up. You dampen the foam with water first, (I use a spray bottle to do this), smear the cavity with the glue, then place your wrapped servo in the cavity, again weighing it down. As the glue dries it turns into a foam which fills every nook and cranny and then is really easy to trim with a blade. This glue is also perfect for gluing wing spars into foam too, but again you must weigh it down or the expanding foam will push the spar out of the slot.

That's a good method Steve, which I was going to use until I found the SLEC servo-covers (which I particularly like as they shield the servo-arm). These hold the servos very well in themselves, but as they screw into the dowels at each corner, they're dependent on the dowels not moving in the foam over time! So I'm inclinded - now I've excavated the space for the servos plus a little bit extra - to line the foam around the sides and especially the corners with plenty of epoxy and micro-balloons.

I once tried Gorilla Glue on something else (fixing a retract housing in an E-Flite Hurricane), but found the foaming too unpredictable, so happier with epoxy generally.

[Jonathan M]

Cheers for the heads-up Jack.

[Jonathan M]

Kid gradually on the mend, so got a bit more time to concentrate on the MP today. Flushed-off the bottom cross-decking, then sanded.

Followed instructions (always a good starting point!), inserted battery most of the way through its opening, and marked the forward limit.

Instructions say to use scrap 1/8 x 1/4 to hold the front of the battery, but I added a floor cross-piece first for extra rigidity. Adjustable bevel helped get the angles roughly right for this, and the forward 'bulkhead' which was glued in afterwards.

I should have added some stiff squishy foam to the battery bay before adding the top decking... but I didn't!

[Jonathan M]

Next up was to add the top nose decking. Mindful that there was going to be very little sheeting available, I was careful not to waste any more than necessary.

Working forward, with the first section glued up, carefully marked and cut the next one along.

Found it was worth slightly bevelling the edge of the loose piece to match the glued one.

Penultimate piece.

And ran out of stock! But as the final sanding will bring the thickness down at the very front, found a piece of scrap would do.

[Jonathan M]

While waiting for the SuperPhatic to dry, got to work with making up my first aileron servo extension leads. (Good article on doing this in the October 2016 issue of RCM&E: basically don't strip any more or less than 4mm insulation off the wires.)

Being stupid and always making mistakes with wiring, took huge care to mark up the correct polarity one each plug and each socket before proceeding!

Finally, checked the wiring. The keen-eyed with have long since spotted that I'm sticking with my original plan of running a scalpeled-out groove in the foam to bring the extension wiring to the wing roots before gluing on the balsa LE - because it seemed quickest with the available equipment!

[Jonathan M]

Final work today was flushing-off and sanding the nose decking...

...and roughing the bevel for the sloping ply piece that will meet the front edge of the wing.

Tomorrow - or whenever - will radius the fuselage corners etc then cut out the hatch.

Jon-making-progress

[Mike Etheridge 1]

Wonderful finish on the fuselage , but you might need some lead ahead of the battery to get the C/G right. When I made my dark blue Flair Heron over 30 years ago I needed a fair amount of lead as can be seen in the photo. I also needed to add lead to the Middlephase 2 having made sure the battery could be fitted as far forward as possible.The fuselage hatch on the Heron gave complete access and I was able to fix enough lead with epoxy  glue to get the CG right. I seem to remember  having to cut into the nose area on the Middlephase 2 to glue in some lead?

 The Flair Heron originally had one servo set within the wing centre and Bowden cables linked to the ailerons. When I damaged the wing my nephew repaired it and removed the Bowden cable links and introduced torque arms which meant that the snake tubes had to be splayed out within the fuselage. 

Edited By Mike Etheridge 1 on 05/01/2018 22:58:48

[Jonathan M]

Posted by Mike Etheridge 1 on 05/01/2018 22:38:22:

Wonderful finish on the fuselage , but you might need some lead ahead of the battery to get the C/G right. When I made my dark blue Flair Heron over 30 years ago I needed a fair amount of lead as can be seen in the photo. I also needed to add lead to the Middlephase 2 having made sure the battery could be fitted as far forward as possible.The fuselage hatch on the Heron gave complete access and I was able to fix enough lead with epoxy glue to get the CG right. I seem to remember having to cut into the nose area on the Middlephase 2 to glue in some lead?

Good point and really useful photo - thanks Mike.

I did wonder about this. The MP's flat-bottomed hatch ends just aft of the battery bay, as designed. Extending it forwards to give access to the nose bay would involve cutting its base at more of a downward angle towards the nose, which curves down at a more extreme angle than the Heron, but this might risk weakening the foremost structure?

But there remains a gap at the top of the battery-stop bulkhead I glued in yesterday (roughly 10mm high by 30mm wide), so some jiggery-pokery could allow for thin epoxy and lots of small bits of lead to be dribbled over this into the foremost compartment by holding the fuselage vertically down. If this isn't feasible, an access hole (say 8-10mm diameter) for the shot-and-epoxy soup to be poured in could be bored in the top and plugged afterwards.

Also, given the lighter weight of modern RC equipment, I've left the elevator snake well over-length for now, about 50mm, and will do the same with the rudder snake when I fit it, to allow the servos to be fitted further forward than indicated in the 1980s instructions.

[Trevor]

I'd recommend leaving the final piece of nose sheeting off until the rest of the model is finished and covered so that you can see how much lead is needed. Then fit, say, 80 - 90% of it in permanently before closing off the nose.

Then, if you don't make your battery retainer full depth (i.e. leave a gap above or below it), you should be able to drop further small lumps of lead in there as needed, followed by a piece of foam. Don't stuff the foam in too tightly though or, if you do decide you want to take some lead out, you'll have an interesting time with the tweezers, getting it out!

Trevor

[Mike T]

I'd put the lead in 'dry'. That way you can pack down the lead thoroughly (tap the nose on the floor) and dribble in the epoxy afterwards. Warm the front end to thin it so it fills all the cavities. Trying to get a 'wet' mix in there will end in tears!

[Jonathan M]

Good suggestion Trevor, but I've already completed gluing on the sheeting to the nose.

Also good tip Mike to go in 'dry' then dribble thin epoxy in after. To make all this a little more feasible, I've been sketching on the fuselage side possible options to improve access to the nose cavity.

First is to make the removable-hatch 7" long (instructions say 6" long) so closer access to get stuff through the battery aperture in F8. Second is to bore a 1/2" hole through the middle of the bulkhead in front of the battery, which can be sealed with a bit of 1/16" ply and epoxy once I've got the right amount of lead in.

Edited By Jonathan M on 07/01/2018 20:41:34

[Jonathan M]

Posted by Trevor on 06/01/2018 09:17:42:

Then, if you don't make your battery retainer full depth (i.e. leave a gap above or below it), you should be able to drop further small lumps of lead in there as needed, followed by a piece of foam. Don't stuff the foam in too tightly though or, if you do decide you want to take some lead out, you'll have an interesting time with the tweezers, getting it out!

Trevor

Actually, re-reading this good advice, I'm inclined to not epoxy any of the lead in. I'll extend the hatch to 7" as planned and bore a reasonable hole through the middle of the 1/8" bulkhead for insertion/retraction of rectangles of lead sheeting. Then there's a good chance I can get away with stiff foam on top as a removable 'hold-down' for the lead, after which the whole nose-bay can be sealed by a screwed-in piece of ply. I'd also like to line the battery bay with foam to reduce shocks to the NiMH.

I like 'flexible' solutions. Will see how achievable this is once I've cut the balsa.

[Jonathan M]

Today...

Finalised the fit of the servos in the wing-pockets (excess aileron leads coiled and taped to servo side where there's a bit of room) and drilled 1.5mm diam pilot holes.

Trimmed the pocket surrounds for an exact fit, and down slightly so that the 2mm thick plastic covers sit as flush as possible.

Selected the two denser strips of the four lengths of supplied stock for the leading-edges (the remaining two will face the trailing-edges).

And glued up using PVA and masking-tape (used lower-tack tape than the blue 3M stuff as I don't want to risk tearing up fibres from the veneer when I peel it off).

[Jonathan M]

Just to point out that I haven't gone off the build in the slightest - just been off everything for a week with The Dreaded Lurg

Hope to be back on the case as soon as possible!

[Jonathan M]

Hurrah! ...back on the MP after 5 weeks of very pear-shaped life stuff.

Shaping the LE and flushing the TE of one wing:

Roughing out LE - prefer a block-plane over the razor-plane for longer jobs like this.

Pencil-hatching warns me when getting a bit to scarily close to veneer.

220 grit - first supported with a block to keep the line true, then wrapped in the palm to finish.

Flushing off TE (added pencil hatching only once got closer to the veneer).

Finished off with sanding-block.

Phew!

[onetenor]

Beware! Casting in damp anything. It can create steam which can cause an explosion and blow back of molten lead. Wear gauntlets, long sleeved overalls and a full face shield. Hot lead /solder is very uncomfortable on your skin to say the least and leaves very deep scars. Ask me how I know. No? well I'll tell you anyway.. As well as being a motor engineer I was a plumber and have the scars ( luckily small ones ) to prove it. I also have cast my b own fishing weights/ As result of these things I have seen a few "Blow Backs " asI call them. Please be warned. Burnt hands can become useless if badly burnt and we couldn't continue the hobby we love if that happened.

[Jonathan M]

Thanks for the warning Onetenor. I won't be casting anything for the MP however, just securing cut roofing-lead with epoxy (nose cavity) and a bolt/butterfly-nut (ballast).

[Jonathan M]

Maybe I'm being perickerty (or maybe I've just been conditioned by too much indoor FF scale where accuracy is vital or DLG mouldies where precision is similarly important) but my aileron stock looks a bit too thin really for the wing's flushed down rear facing, which looks theoretically like this:

Unlike the picture above, the leading edge of the actual aileron is about 8.5mm whereas the facing only comes down to 9.25mm. If I reduce the facing any more, then the wing will acquire a weird bump in the aerofoil. Need I mither about this, or would it be worth laminating some 1/32 sheet to one side of the aileron stock to build it up to thickness?

The other issue to address is that the the aileron stock needs fettling so that the edge is square to the bottom surface of the wing - in its current state it lifts (to effectively give the whole wing reflex).

Finally, I've abandoned the plan of building up solid wing-tips as per the original MP. I'll just use the facings supplied, but will first glue on a stub of aileron stock (about an inch, as per the wing on my ARTF Acrowot) then flush this off before gluing on the veneer facing.

More anon...

Jon

[Jonathan M]

Continued with the build today... and err... here this evening with the shameless detail - just in case someone else decides to build this version with 'new improved' aileron wing details that don't... err... quite match the instructions.

I won't mention the aileron that I cut in the wrong place (lesson learnt: cross or rub out all lines on balsa that aren't intended for any final cut!), except that it was scarfed back to integrity with some scrap wood!

[Jonathan M]

Aileron stock edges shot square with bottom edges, then 5" root pieces cut (in the right place this time!) and glued with Super 'Phatic (what a pleasure it is to have a relatively fast adhesive that isn't either epoxy or CA):

And tip pieces also glued on (pins didn't provide enough pressure, so these were re-glued and held with tape instead):

After root pieces flushed off, wings dry-taped together to check for basic fit on fuselage (not entirely happy with seating, looks like a little scribing into fuse will be needed in due course):

A happy perspective for the first time! Much work still to do, but gives a sense of the finished article. I'm going for the flat wing, no dihedral, just the 'rising-taper' in thickness on the underside to avoid the 'droop' look:

Tip TE piece flushed off, ready for the capping piece:

Veneer capping piece glued on and taped up:

I wasn't confident in the very short tip TE piece having sufficient strength with just the veneer cap on the outside, so cut a bit of scrap veneer to inside face, hopefully this will toughen things up:

Ta-dah! Wings joined with fast epoxy:

Final wing jobs will be bandaging join with supplied weave and Poly-C, and making up the ailerons.

Jon

[Jonathan M]

So this is my plan for the 'bolt-on' wing solution. Based on CF's scheme for the non-aileron wing, but moves the rear bolt fixing forward to 41mm from the TE (was shown at about 15mm). Also adds a balsa 'seat' glued above the ply plate which itself is epoxied under the top longeron.

The job of the wing 'joiners' are mainly to provide a hard seat for the nylon wing bolts, so they don't need to extend beyond the 4" wide glassed-on wing bandage.

Plan also shows the solution for fixing ballast to the fuselage base cut from 2mm thick roofing lead offcuts. Each 'leaf' weighs about 2oz and be increased in allows increments up to say 8oz, and each has a slot rather than just a hole so CG can be adjusted if needed when in use.

Here the wing marked up for the cut joiners. CF specifies hardwood but I'm using dense pine, which will be more than robust enough for the job - and will be easier to flush off afterwards!

With no apologies for mixing French units of measurement with proper British ones....!