Topic: Miles M52 55mm EDF Build

The Miles M52 is another one of those British designs that really captured my imagination – like the SR177, TSR 2 and P1121.   I have wanted to do an EDF version since I finished the SR177 2 years ago.  With the demise of my first EF16 in the Summer I had a spare Phase 3 fan fitted with a Don’s Wicked motor available, so I worked out intake and exhaust areas and scaled a 3-view drawing appropriately.  However, I never seemed to have the time to sit down and get stuck into the design work until the chance finally arose in October when I was at sea for a week with work.  I put in a few hours in on AutoCAD every evening and finished the fuselage and cockpit pod, but I didn’t have Profili installed on my laptop though so couldn’t do the wing, which had to wait until I got home.  I have used ideas from several different kits and designs I have seen to arrive at where I am now (eg the all moving tailerons from the EF-16, sheeted core structures for the fin and tail planes from the West Wings Hawk).   I was quite taken by the idea of getting all the parts CNC cut and made enquiries with a firm that advertises the service usi :''g their published contact details, but when, after 3 weeks, they hadn’t replied to my 4 e-mails I contacted SLEC on a Tuesday afternoon and was given Ian Hull’s e-mail address.  When I got home that evening I sorted and arranged the parts to fit their standard size balsa and ply stock.  No need to add the bridges to hold the parts in the sheet because their CNC software does that for you.  Ian got back to me with a quote on Wednesday, I accepted when I got home and saw the email and they started working on the files on Thursday.  The following Wednesday I was told that the parts had been cut, I paid by PayPal and the courier delivered them Thursday morning…………….9 days from initial enquiry to delivery 
Last week I printed the plans and stuck them together.  My only concern is that it looks as if it might be a little big for a 55mm fan, but it is too late now. 

I have resisted opening the parcel until this evening because I wanted o get the V-1 out of the way first.  It was well packed to protect the wood, on opening there were only 2 parts that had broken free.  To be honest it could have happened anytime, even whilst I was cutting through the cardboard and there isn't any damage anyway.  The Laser cutting is excellent.  I am also very pleased with the balsa selection.  The balsa parts are all in 3.2mm, the large Ply sheet is 3mm birch and the small 300x300mm sheets is 1.5mm birch.   I don't like using lite ply because I find it warps and just isn't as strong.
All-in-all, SLEC have done a first class job and have saved me hours of cutting.  I am extremely happy with everything and would have no hesitation in following this route again (P1121 next!  ).
Will start the building proper tomorrow.  Any questions or pointers then please do chip in.
Regards

Pete

That cutting looks superb Pete. The turn around is outstanding too.

I wish I'd sent my Canberra to SLEC first time round now.

How big is it compared to the F16?

Wow, that's lovely.

What wingspan, and how much would the power set up to buy from new dizz?

Can I assume SLEC could provide more kits with your approval for the rest of us?* 

*I imagine you'll want to prove it flies first though.

I'd quite like another EDF chuckie and something different would be great!

Fascinating to see one of these being built.  I've been thinking of making one, but with longer-than-scale wings so it could glide.  A sort of EDF-assisted glider really.

Looks really good, a fascinating subject.

I shall be following this one with much interest, great job on the drawings.

Bert

Wow!
So much  interest thanks, overnight too.
To answer the questions..............
Yes, having had more time to caress and fondle the cutting am even more impressed and I can't imagine how much time it has saved me, yet alone the improved accuracy. Size comparison:

                     M52            EF-16
Wingspan       680mm       660mm
Length           770mm       914mm
Wing Area      9.1dm²      12.6dm²
Scale wing span would have been 545mm

Have bought several times from Don, great service no hesitation in recommending.  Of course you take the import VAT risk with buying from abroad.
Dons Wicked 4800kV EDF motor and pentium ESC:
DonsRC -  (Powered by CubeCart)

Phase 3 Fan:
http://www.brchobbies.com/?page=shop&item=729
That set-up got my first EF-16 to 97mph S&L on 4S, no wind, so plenty of power.

There was a one-off set up charge (am guessing that was for importing the files into the CNC machine and the software adding the bridges), so that wouldn't be applicable if I get any more cut.  However, it needs to fly first and there may well be mods to the design required as I progress.  Am shying away from quoting costs because I don't want to mislead - obviously each quote will be different depending on how much CAD work SLEC have to do and the materials used.

Good grief Dizz, that's a bargain. Defo watching this build...

2/3 of the F16 wing area? That's should be alright because the F16 can be brought in at a jogging pace. Even allowing for a higher weight it should still fly well 

You 2 are quick of the mark.  I accidentally hit post before I had finished  

I just remeasured the wing area more accurately.  Both figures conventionally include wing area covered by the fuselage.  I spent quite a bit of time arriving at the wing size as a compromise between being big enough to work and scale look.

Because I have several Phase 3 fans (P3F) donated by dead Fantoms and EF-16s I have started several designs for that unit.

Christmas present shopping with daughter No3 now.  More this evening.

Pete

Just spent an hour identifying all the CNC parts and marking up the wood – first lesson identified  make a note of what bit went where on the files for cutting.
Will be starting with the cockpit pod but not sure how much I'll be able to get done this evening.

I cut the cockpit parts free and did a test fit earlier.  A couple of slots will need sanding to enlarge slightly, but all the formers and longerons locked together nicely dry – a good omen for the fuselage.  After sanding and final fit I'll run thin cyano into the joints.
Started thinking about a colour scheme, am not keen on all silver. 

The yellow might be good.  I believe yellow was the official prototype colour of the RAF at the time or something?  So it's very valid.

I reckon you should cover it in Flitemetal Pete. I'll send you a roll if you like 

That looks so good Dizz, coming together well......

Is this being skinned in balsa?

Yellow would certainly be visible and dead easy to paint.  Think the slightly earlier MB5 was painted like the second one.  
Mmmmm, metal covering..........how heavy is it?  I was going to glass it and spray.  Seem to have developed a reasonable technique now.
Yes, intended to skin with 1.5 and 2mm balsa Stuey (watching Family Guy at the moment  )

Eased a few of the slots then assembled the cockpit pod.  Held the whole lot together with elastic bands, checked it was true and applied a spot of thin cyano to each joint.  Cut some 1/8” square balsa strip and fitted in to the cut outs, securing with cyano again.  The strips are meant to stand about 1mm proud of the formers because they are then sanded back level with the edges of the formers making a far smoother structure.  So that is it ready to sheet tomorrow, probably about a hour total from cutting out to achieving this already very stiff and strong state  – would have taken me an hour just to make 3 formers in 3mm ply.

Couldn’t find any colour photos of the MB5, just this static model.  I quite like this scheme but will continue to look.

According to someone on RCG, Flite Metal weighs 0.00222 oz/in².

I don't know how that compares to paint but I can easy send you a sample if you wish to compare it to traditional finishes?

I don't have any digital scales (because they'd scare me). 

I was under the impression that the M52 was to be polished metal like most of the experimentals at Cosford. 

According to someone on RCG, Flite Metal weighs 0.00222 oz/in².
I don't know how that compares to paint but I can easy send you a sample if you wish to compare it to traditional finishes?

Ok, that would be good thanks Jamie.  I assume it goes stright on to the wood, so I wouldn't need to glass, etc.  It would certainly turn a few heads 

It's incredibly thin, so goes best onto a glassed surface Pete. It likes to be burnished down a bit. You are welcome to experiment a bit though  

The issue would really be whether it weighs any more than a coat of paint? 

This is going to turn out heavy again anyway I'm sure - I just don't seem to be able to build light!  4g of paint just on the small V-1 with sprayed car acrylic, I only added 15g to the last funfighter I did with Humbrol enamel.
Was thinking about the metal finish and radio transmission in the shower just now.  A mix of metal on the fuz and sprayed different shades of silver/ali on the wings to pick out panels (or vice versa) might look good and get the aerials in the clear.  
Also how to get more thrust out of the P3F, thinking more blades on the same motor with a 60amp ESC, but will start another thread to ask that question when I get back from the shops.

I used some software called Cone Layout to make some templates for the pod sheeting.  I cut the balsa a mm or 2 over size and trimmed to fit accurately as I glued it in place (the rear is done too).  The program will export the template as a .dxf file, so I have added them to my main M52 file.

I spent a very therapeutic 90 minutes watching the TV removing all the parts, cleaning up the edges and checking fit/dimensions.  I only have 3 very minor changes to the CAD drawings so far.  Then I Fabloned the wing plans, idea being that the cyano wouldn't stick to it later; also extended all the lines past the wing edge for marking back onto the balsa sheet idc.  Another CAD plan lesson identified - could have done that before printing.

Wing sheeting from 1/16” medium balsa edge joined using sticky tape and cyano, then sanded smooth.  Built over the plan using medium cyano.  Bottom spar 3mm square hard balsa, top spar bass wood.  Highly technical reason I didn’t use bass wood for both spars………I didn’t have enough.  The TE was sanded to a taper to accept the top sheet (similarly sanded).  There is 1/16” vertical webbing connecting the spars, but I forgot to take a photo before I added the top sheeting.  The wing as it is in the 6th photo only weighs 24g  .  BTW, cyano sticks to Fablon, right wing wing plan will have sticky tape added along joint lines (I know that works).

Wing will be attached to the fuselage by 3 x 3mm square stub spars that extend 15mm into the wing and will plug into slots in former doublers.

Remembered to take a photo of the spar shear webbing this time.  The wing is very stiff, am happy that they will be more than strong enough especially once glassed.  Realised that I forgot to build in some washout on the left wing last night, so this one had to be built flat too.  May be able to steam a bit of twist in later................. if I can be bothered.

Made the second wing this morning then during the course of the day sanded the tips and roots to make both wings exactly the same size, made LE and tip templates, shaped the LEs (a lot of job satisfaction using the razor plane ) glued on the tips and sanded everything flush/smooth.  Wings weigh 21g each now and are nearly ready for glassing, I just have to round off the root and tip leading edge sections.  If I remove balsa where indicated by the black scribble at the tips and from the underside at the root, I will effectively build in a degree or two of wash out.  Phew  

Haven’t posted a photo of the largely completed cockpit pod yet, so here it is after a coat of sanding sealer.

Looks great Dizz.... Really coming on and inspiring me to do a bit of balsa bashing very soon....

as for the washout, it looks too well engineered to accept any twisting... 

You are right Stuey, no chance of steaming in a twist, but the differential sanding has done the job.  Will start on the fuselage later this afternoon, just printing a mirror image for the left side so it can be built over the plan too.
Pete

Will the air intake be big enough or will you have holes underneath the fuse?  Actually that's probably a silly question, you're bound to need 'cheater' intakes with such a narrow 'official' intake.

Most of the aeronautical engineers who dabble in modelling claim that cheater holes are a waste of time.

I reckon it'll be fine as is though. The FSA of the Phase3 fan isn't that big and although the intake is narrow it's a huge diameter compared to the fan so I reckon the intake area will be ok.

Looking good though Pete. I'm quite tempted myself. I damaged the EF16 this morning bouncing down the ice on landing. The epoxy is curing at the moment but it's made me realise that little plane is aging now and generally getting a bit tatty...

No cheaters, that is, well, er, cheating!  
I adjusted sizes to get a scale intake size at 110% FSA IIRC.  I wrote a spreadsheet that does the sums which makes intake and exhaust "what-if" calculations quick and easy, posted below.  
Thats the trouble with foamies, they get tatty quickly unless you do some modification work to start with.  Mind you landing on ice isn't the best way to prolong the life of anything!  
Had a dig through the spares box and found a GWS impeller and a spare Phase 3 shroud.  With 6 blades it should shift more air if the 4800kV motor and ESC can provide the power...........one way to find out, can feel some testing coming on tomorrow.

That spreadsheet is brilliant.  What a good idea to calculate it properly instead of just hoping for the best.

That spreadsheet is brilliant.  What a good idea to calculate it properly instead of just hoping for the best.

Thanks, it has saved me loads of time when I have been messing around with other EDF designs/ideas.........there is a clue in the sheet 

The fin internal structure made up over the plan from scrap 2mm hard balsa, then skinned with 1/16” medium from off-cuts.  Cut to the correct shape, soft block tip added then the LE and TE sanded to streamline section. 

I am going to have to fit a lot of gear and rig the tailerons as the fuselage is built.  I have an idea what order I’m going to achieve things, but no doubt that will change as I progress.  To start with. the upper and lower fuselage longerons were pined over the plan and the formers dry fitted.  Everything (except F9 and F10) was an excellent interference fit and when the side longeron was added the whole lot squared up and locked together to form a strong frame work even without stringers or glue.  
Back to F9 and F10: the cut out for the exhaust ducts are correct, as are the outside diameters, but I made an error in drawing the longerons and as shown in the photo.  I have got around this by trimming a wedge starting at F8 back to 2mm wide at F10 and packing the former cut outs with a small 3mm balsa cubes.  All I need to do is run thin cyano into the joints, but I’m holding off for a while because in the morning I need to cut some holes in F2, F3 and f4 for servo and motor wires to pass through...........got to make up and test the new fan too.

I finished off the tip of the nose cone today.  Several more coats of sanding sealer and it is now ready for a coat of grey primer once I have made the canopy. 

I Drilled some 10 and 6mm diameter holes on ply formers F3 and F4 and used a ¼” brass “Soft Bore” hole cutter on balsa F2.  Dry assembled right fuselage side again, checked square and ran thin cyano into the top longeron joints.  Checked positioning of the bottom one and glued joints.  Did a final check of the side longeron and secured that too with cyano.  Left it for 5 minutes then eased it off the building board and made the left side in the same way.  I clamped the 2 halves together and checked the seams were straight and ran thin cyano down the joint.

The balsa fan doubler on F3 also makes the spar pockets.  1/16” ply on that then a balsa disc to accept the intake duct.
Obviously had to put all the bits together just to see what it will look like.   

That's looking really good 

I doubt I have anything worthwhile to add, but I'm enjoying this build (and fancy one too)!

If I do use the GWS impeller looks like I will have to remove the centre of the rear pod former to increase clearance.  I might do this anyway as it will draw air through the cockpit and help cool the battery pack.  
Now I have the basic fuselage structure the intention is to build from the inside out.  I used “Cone Layout” to make the duct templates and cut the intake from 1/64” ply.  I need to use ply because the cockpit pod will be glued to it eventually.  There is approx 5mm overlap arranged along the bottom 2 longerons.  I used a Permagrit grinding wheel in the trusty Dremel to chamfer the edge then rubber the internal surface down with 400 wet and dry to get a nice smooth finish.  I need to do a bit of sanding to the ply edge at the fan end tomorrow.

Cheers Jamie...........................but it has to fly yet mate!
So far it is working out as I hoped it would when I drew it whilst on the way to Gib.  There are a few minor draughting errors so far and only 2 more CNC bits to do (canopy and fan hatch).  Definitely nothing worth another set up fee to change the CNC files. 
Latest thing I noticed when I joined the 2 fuz halves is a fraction of a mm gap down the middle between the formers, you can see it in photo 7048 in post#35, couldn't see any gap whilst it was n the building board.  That will probably be due to me drawing at 3.2mm, a thou or 2 of cutter inaccuracy and the fact that 1/8" nominal wood thickness is exactly that - nominal.  Am not worried though, that fuselage structure is already far stiffer than many kits I have built at the same stage.

Your not hanging about . . . . your on a mission!