Topic: Miles M52 55mm EDF Build

Hi Pete bet that will go like a "rat up a drainpipe" really looks the DDs,are you taking it to Weston would love to see it?
Has he been for his morning run yet or would'nt he shift off the couch
Enjoy the rest of the week
John

Hi John, since it is you I'll bring it to Weston    He was on the bed when I got back, but he has had a good run around Berry Head this afternoon in the snow.

Finally got around to some fan testing today using the stand and scales as shown.  Unfortunately the GWS impeller couldn’t take more than 1 run and now looks like below.  However, having had a look at the figures maybe it wasn’t such a bad thing: at the 1 minute WOT point it was pulling 9.6 Amps more than the 3 blade Phase 3 impeller for only 18g extra static thrust.  It would have required use of the 60 Amp ESC which would be very difficult to build into the intake duct and weighs 12g more than the 40 Amp one – so lots of pain for a mere 6g benefit.  I forgot to measure the GWS efflux velocity, so can’t compare, but the P3 impeller gave 145mph and from my rule of thumb I estimate the S & L speed will be around 120mph (at a scale of 13.1:1 = 1572mph).

Hi Buddy, guess the GWS fan is a no go then.

The rest look 'kin fab though.

H

What was the thrust of the Phase 3 incidently Pete? Just wondering how much thrust 4 of them might give 

I reckon I'm gonna have a go at making a vacform machine on the strength of what you've described 

Looking at about 32Amps WOT.  Applying the 80% rule that calls for a 40 Amp ESC so the 60Amp can go in the P1121 idc.  I removed the heat shrink from the heat sink and cut a hole in the inlet duct for the ESC to sit in.  I made some extension leads for the taileron servos and extended the battery wires.  ESC held in place with a bead of Zap-a-goop and 2 small balsa wedges.  View down the intake shows the ESC heatsink right in front of the fan face and the power leads entering the duct behind where the cockpit pod support will be.  This shouldn’t create very much drag.  
Eric arrived today as well.  I went for a leather flying helmet in the end and this 1/14 scale light weight resin job from Pete’s Pilots looks right to me.

Hi Buddy, guess the GWS fan is a no go then.

The rest look 'kin fab though.

H

Yep, thats a 4800kV motor so it was doing about 57k rpm when suddenly all the blades came off  

What was the thrust of the Phase 3 incidently Pete? Just wondering how much thrust 4 of them might give  

I reckon I'm gonna have a go at making a vacform machine on the strength of what you've described  

As you can see, on the test stand there isn't any ducting, so the thrust I'll get installed will be different, but the last run on 35C 2200mAh 4S started at 640g and settled to a steady 590g after 40 seconds.  My first EF-16 had the same power train and had a T:W just about 1, I can't remember how much it weighed, but it was definitely more than 700g.

Hi Pete,
Not sure how I missed this build - good job - the M.52 is looking very good indeed. I am awaiting a set of parts back from SLEC (my very first cut-files, eek!) and your comments on their service also match my own experience to date.
Paul W.   

Smallest jobs take the longest time: took an hour to fit the fan and another 90 minutes to make and fit the link to the exhaust ducting.  Before going to far though I did test everything because once the last bit of fuselage sheeting went on major surgery required to get at anything.  In my excitement the predictions I made yesterday should have waited until the installation was complete to be relevant.  I couldn’t use the scales to measure static thrust, but with the fuz held vertical and on full power it wanted to go up on the 2200 Lipo (weight 696g) and just started to fall on the 2500 Lipo (715g) so I estimate the thrust at about 700g, which I’m pretty happy with.  Efflux velocity was 121mph, apply my estimation rule and S&L speed will be around 90mph allowing an additional factor for the large disc around the exhaust which will affect airflow around the back end.  Everything held up ok, in fact the fan was very smooth, if extremely loud, so I trimmed and fitted the last bit of 2 mm sheeting.  Once the damp balsa had dried I attacked the remaining joints with a coarse permagrit and finished off with 240 grit wet and dry paper to get a decent, smooth shape.  Obviously had to put it all together, but can’t compete with Jamie’s Meteor shots in the snow.  
Am actually rather pleased with how the M52 is coming out, weight of everything in the photo, including the battery and the remaining parts still to be fitted came to 855g – only the fuselage glassing and the paint job to add.  T:W will be approx 0.75.  A quick C of G check had the balance point about 12mm ahead at the moment, so still looking good to be pretty close. .
The fuselage has been filled, awaiting it to dry before sanding and then l try and get the glass cloth stuck down before turning in.

Hi Paul,
Thanks.  Not so busy at weekends now I'm back at Devonport so I'm hoping to be able to get to a few more e-fly ins this summer, hopefully be bringing this and the SR177 with me.
Will be doing a P1121 next and will definitely be using SLEC to cut it - it is so accurate and saves so much time.
Like your E28 too 
Pete

Thanks Pete - looking forward to seeing those two models of yours in the flesh!
Paul W.

No photos worth taking this evening.  Fuz was glassed with 50g cloth last night, lumps and bumps sanded off this morning and flow coat applied before I went out.  To make it easier to see how much has been removed when sanding down to the final finish I colour the epoxy with a dedicated pigment from Fibretech; if you remove too much resin the white cloth becomes visible = time to stop.  Final sanding when I got home was pretty easy because the epoxy was still a little “green”.  Have sprayed with filler/primer and it is currently drying.  Am out all day tomorrow so next update will be on Sunday.
Fly Navy has located an alternative full body Eric that looks as if it will be exactly the right size and has kindly posted it to me to hopefully be displayed in the cockpit.     John wondered if my Eric is named after Capt Eric “Winkle” Brown CBE DSC AFC RN………..yes he is!  There are a few pages about the M52 project in his book “Wings on my Sleeve”.

Wings on my Sleeve

Great book, great pilot - what might have been...?!
Paul W.

Been thinking whilst heading down the M5.............. am going to have to set some negative incidence on the tailplane wrt the wing, how much though?
Would -3 degrees be enough?

Home about 20.30 so hopefully someone will help me decide by then as I want to crack on with it tonight.  No1 Daughter managed to get the HUmbrol enamels for me todayso I'll be able to airbrush tomorrowif I can get it glued together.
 

Hi Pete,
How goes the final assembly and Painting - are you going for yellow?
Paul W.

Hi Pete,
How goes the final assembly and Painting - are you going for yellow?
Paul W.

By the time I got back, had a shower and cooked something to eat I didn't feel like building, but I did manage to spray some aluminium paintdown the intake and on the cockpit pod.  Am going for yellow undersides and dark green/grey camo uppers.

 

Am going for yellow undersides and dark green/grey camo uppers.

That'll look very good - though I hope the camo isn't too effective!
Paul W.

On incidences -  depends where your CG is. If you've accepted the calculated CG (rather than moved it forward "for safety") and the wing loading isn't particularly high I've start at -1ish. If you've opted for a "safety" CG or the wing loading is high then -3 to -4 may be needed.

£0.03 supplied,

PDR

Hi Pete,
WRT to taileron setting – your 3 degrees sounds like a good place to start.  The wing section is a flat-bottom lifting section – is it set with the underside parallel to datum?  That will give you an effective wing  incidence of something around + 2 degrees?  Assuming that the model will not be too lightly loaded (!), that combination ought to take a fast flying model on an upward pathway off the ramp?  Wonderful to have instant incidence-change available on the elevator stick though!!
Paul W.

Thank you both for taking the time to reply.  The reason I am keen to get it in the right place is because I have to fill the root area with balsa block and it would be good to to have it aligned with the taileron.
Wing is indeed a flat bottom section with the bottom aligned to the fuselage centre line. Profili shows zero lift a about -2 incidence.  C of G will be slightly ahead of calculated and it won't be lightly loaded so I'll stick with minus 3 degree on the tail plane.

Haven’t been able to do much today as unexpected visitors arrived at lunch time, however this morning I used a new blade to cut around the fan bay hatch opening.  I glued the removed skin to CNC ply hatch formers and cleaned up the edges.  I stuck clear tape to the edges of the opening, replaced the hatch and filled the gaps with plastic padding.  Excess plastic padding sanded off whilst it was still soft and the hatch removed.  I cleaned up the edges again and then replaced the hatch to sand everything flush.
The ESC has heat sinks on both sides of the board, so too get some cooling air over the side inside the fuselage I cut 2 holes in the skin and made some air scoops from plastic spoons (care of the supermarket café).  Not scale, but they won’t be very obvious once painted.
1/8” square wing attachment stub spars cut to length and secured into the slots in the wing ribs with thick(slow) cyano.  I then also wicked thin cyano into the joints so the approx 80mm of spar inside the wing to well bonded to the ribs and wing sheeting.  Area has had a coat of filler primer and has been left to harden until tomorrow.

Hmmm...ifyou have the wing at an effective incodence of +2 then I'd be more inclidned to mount the tailplane at zero. If you put the tailplane at -3 you'l have an effective angle of -5, and that sound way too much.

PDR

just watching a short clip of dennis bancroft on Dave..... and some archive m52 shots...

Hmmm...ifyou have the wing at an effective incodence of +2 then I'd be more inclidned to mount the tailplane at zero. If you put the tailplane at -3 you'l have an effective angle of -5, and that sound way too much.

PDR

Mmmmmmmmmm, decisions, decisions 
If I hadn't been sat in the car for 8 hours yesterday I wouldn't have even considered it

just watching a short clip of dennis bancroft on Dave..... and some archive m52 shots...

Is that in the Hudsucker Movie or Dave +1 and Top Gear?

Is that in the Hudsucker Movie or Dave +1 and Top Gear?

nope, it was an edition of speed with clarkson looking at going fast in a plane.. recorded from earlier today... might be repeated...

nope, it was an edition of speed with clarkson looking at going fast in a plane.. recorded from earlier today... might be repeated...

Thanks, got that clip from You tube.......but worth watching the programme again anyway 

Sprayed some yellow and more aluminium (around the intake) last night.  Wings have been glued on with 12 hour epoxy and left jigged to cure until I get back 0100 tonight.

Wings are rock solid 
Masked and sprayed the fuselage, which is now drying overnight so I can handle tomorrow morning and get the cockpit in before being away with work for a couple of days. 
Eric 2 was waiting when I got home, unfortunately he might be a little too tall to fit without surgery to remove his boots and sort out stiff hips.  It would be a real shame to hack him up so I will take a better look if I can squeeze him in whole some how later in the week.

You will need to finish off his oxygen mask Pete,I only plonked a bit of filler on it and moulded it somewhat ,needed to cover his mouth and nose up
Sshh don't say anything and I won't
John

I set about 3 degrees of elevator down trim then glued the tailplanes on level with the bottom of the wing using 3 hour epoxy and left it jigged all afternoon and evening to set.  Idea is that when the transmitter trim is set back to zero both tailplanes will have exactly the same up setting. The fin has been glued on with 30 minute epoxy: I used 3 x approx 2mm dowels to add some strength.  
Current weight now 663g "empty", 910g with 2200mAh 35C Lipo and 928g with Eric 1.

Looks fantastic buddy, really good

Cheers pal, still got to fly though 
Airbrushing and decals tomorrow.

If I need to get at the tail servos and linkages I will have to cut a hatch, so I marked where to cut with some BDR tape.
Airbrushed the upper surfaces today in several sessions using thinned Humbrol matt enamels 106 Ocean Grey and 30 Dark Green.  Masking always takes a long time, but the paint also took a long time to dry in the damp conditions.  Have left t now for the paint to thoroughly dry and harden overnight.  In the mean time I’ll make the decals.

Cute - really, really cute Dizz!

Back in the days when I sprayed enamels and cellulose I made a "curing frame" comprising a couple of dozen 40watt lightbulbs mounted on a frame made of wooden batten with 18swg alloy sheet in-fill. This could be mounted over the top of sprayed models like a sort of sun-bed and even in mid winter would cure off gloss enamels in 60-90mins or K&B superpoxy in half an hour. I don't do much spraying these days, but I found it invaluable at the time.

PDR

Thanks.
I don't do enough airbrushing/spraying to warrant a full blown drying rig; I have just shut the door and turned the radiator up to full (11  )

Our local site was sold a couple of weeks ago, so instead of going flying after walking the dog this morning I have rather sadly been working on the M52.
The markings are pretty simple with only the lettering needing to be done on the vinyl cutter.  I produced the graphics file at Christmas and cut them last night.  I made the roundals at the same time, but using SolarTrim and a compass cutter.  
Vinyl doesn’t stick to matt paint as well as it does to a gloss finish, so to give it a hand I smooth the enamel with very fine wire wool.  The decals are lifted from the backing paper with paper masking tape, positioned, pressed down and then the masking tape is peeled off.  Finally the decal is rubbed over with a soft cloth.  Panel lines with a permanent 0.5mm fibre-tip pen.  Pitot tube from ali tube and is removeable.
Current dry weight has gone up to 672g = 918g with a 35C lipo.  Don’t know how it happened, but C of G is at 56mm (looking for 57mm for a 30%MAC).  I will be adding a light coat of clear satin lacquer later to protect the matt paint which will shift the C of G aft a little more and there is scope for a little more lightening in the cockpit.  The aim is once the initial flight has been achieved is to be able to fly with Eric and some cockpit detailing.

Looks really nice Pete,done a cracking job there mate, :afand hope the maiden goes well for you
Sad to hear about flying site have the club an alternative one lined up?
John

Thanks John.  Am pleased that the weights and C of G seem to have come out well too, shear luck!!
We are looking, maybe a field down towards Kingswear.  Not sure what to do if that doesn't come off.
Guinness is a luckily dog today, am taking him out again now.
Pete

Anywhere near a pub with him
John

Excellent work Dizz, and what a perfect choice for EDF