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Middle Phase 2

Kit Build with Aileron Wings

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Mike Etheridge 105/01/2018 22:38:22
1475 forum posts
407 photos

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. 

Slope Soarers

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

Jonathan M06/01/2018 02:59:25
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604 forum posts
267 photos
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.

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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.

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Trevor06/01/2018 09:17:42
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338 forum posts
51 photos

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 T07/01/2018 17:29:06
376 forum posts
28 photos

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 M07/01/2018 20:40:29
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604 forum posts
267 photos

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.

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

Jonathan M08/01/2018 09:17:57
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604 forum posts
267 photos
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 M08/01/2018 19:23:06
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604 forum posts
267 photos

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.

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

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

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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).

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Jonathan M16/01/2018 09:12:01
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604 forum posts
267 photos

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 crook

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

Jonathan M24/02/2018 20:11:09
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604 forum posts
267 photos

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

Shaping the LE and flushing the TE of one wing:

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

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

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

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

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Finished off with sanding-block.

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Phew! laugh

onetenor24/02/2018 22:11:10
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1884 forum posts

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 M25/02/2018 05:47:47
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604 forum posts
267 photos

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 M26/02/2018 20:25:30
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604 forum posts
267 photos

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:

dsc_0458.jpg

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?

dsc_0451.jpg

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).

dsc_0453.jpg

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.

dsc_0457.jpg

More anon...

Jon

Jonathan M27/02/2018 20:10:41
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604 forum posts
267 photos

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 M27/02/2018 20:29:00
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604 forum posts
267 photos

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):

dsc_0462.jpg

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

dsc_0468.jpg

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):

dsc_0474.jpg

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:

dsc_0478.jpg

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

dsc_0479.jpg

Veneer capping piece glued on and taped up:

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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:

dsc_0486.jpg

Ta-dah! Wings joined with fast epoxy:

dsc_0487.jpg

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

Jon laugh

Jonathan M02/03/2018 10:55:26
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604 forum posts
267 photos

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.

dsc_0493 detail sketch.jpeg

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!

dsc_0493.jpg

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

Jonathan M02/03/2018 20:30:08
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604 forum posts
267 photos

Snow enabled play...

Joiner slots hacked out, and bottoms masking-taped to prevent (five-minute) epoxy absconding:

dsc_0497.jpg

Joiners flushed off, extra margin taped off, whole area coated with two layers of sanding-sealer to prevent Poly-C moisture from penetrating veneer, and hole cut in bandage for servo-leads:

dsc_0502.jpg

First of four coats of Poly-C:

dsc_0504.jpg

Next up is making seats etc for wing-bolts and getting everything nicely mated... then onto shaping the fuselage!

laugh

Jonathan M03/03/2018 20:06:44
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604 forum posts
267 photos

Epoxied in the ballast bolt, and made 3mm ply bridges for the captive nuts. Tightening up the nylon bolts with the wing in place so the ply would seat snugly under the top longerons before the 5-min epoxy went off resulted in some creaking sounds... when I later took the wing off I discovered the cause of the creaking: I now have arched bridges! On the basis that it is the nylon bolts that are supposed to shear on an unplanned impact rather than the ply bridges fail and rip out, I really ought to laminate on (curved) strengthening beams under each one.

dsc_0506.jpg

With wing still snugly tightened in place, a straight-edge on the rear decking revealed that one side was several mm higher than the other:

dsc_0510.jpg

Also the wing seat needed shaping to match the wing section each side, so a bit of scribing (0.7mm deeper on the high side) and some gentle work with a miniature spokeshave dealt with that. There's still a bit of a gap near the LE, but I'll worry about tidying that up later with a fillet.

dsc_0514.jpg

The LE needed a bevel cut to match the slope on the rear of the hatch (which is all in the instructions):

dsc_0515.jpg

And glued the curved ply piece in place. I particularly like this photo because it finally shows that I've actually been making a glider rather than abstract sculpture!

dsc_0516.jpg

I've decided to revert to the shorter 6" hatch exactly as per the instructions (rather than the 7" version I considered earlier) and made the down-cut with a razor-saw while the section was still square as it seemed more accurate to do it that way. Tomorrow, after I've shaped the whole fuselage, I'll make the horizontal cut each side and fashion the hatch locating-tabs.

Edited By Jonathan M on 03/03/2018 20:09:49

Jonathan M03/03/2018 20:15:57
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604 forum posts
267 photos

Whilst waiting for things to dry, I also donned nitrile gloves and hacked some of my stash of roofing-lead into four leaves of ballast, each weighing 2oz. Just in case the ballast needs positioning a bit forward or aft of the designed CG, I made a slot in the middle of each leaf. And because lead isn't apparently very good for you, I wrapped each leaf in insulation-tape, after which I binned the nitrile gloves and made a cup of tea!

dsc_0517.jpg

This piccie of one leaf of ballast in place is quite useful, as it shows my 'architect-designed' arched bridges:

dsc_0519.jpg

More later... laugh

Jonathan M04/03/2018 14:53:57
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604 forum posts
267 photos

This morning's work...

First rough your fish:

dsc_0523.jpg

Then de-scale:

dsc_0531.jpg

It seems to look alright from this end:

dsc_0532.jpg

And seems okay from this end too:

dsc_0533.jpg

Slipped fin into the slot I made earlier and bolted wings on again (because I can!):

dsc_0535.jpg

Fuselage looks as shapely and symmetrical as it needs to be... while the black Oracover will I'm sure cover the multitude of small sins!

smiley

Jonathan M04/03/2018 15:17:01
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604 forum posts
267 photos

Just a hint of what I hope to being doing with my MP.... eventually!

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