NCFM Moth build

[isoaritfirst]

Just make a piece of epp that fits tight  into the area where the slugs are loaded. Half round on the bottom wing shape on the top. 

Be very careful though of making good end stops. I have had the Bung come out before and the slugs wreck the wing. 

Easy way is to push a short length of carbon rod or wooden dowel into the wing core from the end of where the ballast tube ends. 6mm should be enough and 40mm ish long. Lots of glueing area. And easy to fix. Bend an old push rod 90 degrees and warm up the end to melt a hole for the rod to fit into. 

[evad]

thanks guys , I think I have the jist of it now 

 

dave 

[Jerry Lunt]

5 minutes ago, isoaritfirst said:

Easy way is to push a short length of carbon rod or wooden dowel into the wing core from the end of where the ballast tube ends. 6mm should be enough and 40mm ish long. Lots of glueing area. And easy to fix. Bend an old push rod 90 degrees and warm up the end to melt a hole for the rod to fit into. 

I don't understand this at all 

[isoaritfirst]

Right from the beginning.     

Cut a slot for the ballast tube. Personally I cut right through the wing with a nice square cut slot. Right up against the spar if possible. 

Then at each end melt a hole that runs as a continuation of the ballast tube. It only needs to be small say around 6mm diameter and around 40mm deep or more. Then together with some glue push a carbon or wooden dowel into the hole. The rod will work like a buffer on a train track, sitting in the centre line of the ballast tube. Any ballast that tries to slide along the tube and smash your wing core will hit the rod and dissipate the shock through the length of the rod

[isoaritfirst]

I then cut a slther of foam off the cut out piece and glue back with pu. 

Ot glues back better than new. Pu sands ok. 

If you want concealed pushrods runing top to bottom I also find it much more successful to cut out a complete slot 5 mm wide right from servo to trailing edge. Install all the rods then glue back on the pieces you cut out top and bottom of the rod. Again dead easy and works better than trying to run holes through. 

[Jerry Lunt]

Now I have it. 

But wonder why the ballast would be allowed the freedom to move.  Maybe unplanned type arrivals could impart strong horizontal spin and the ballast momentum could apply force to the end stops leaving play in the setup.

I like a some firm foam there to absorb this and spring back.

I like the concealed pushrod idea, at least sinking them into the wing so you can have a shorter servo horn, less play, more ......  um  um  what's the word????

[isoaritfirst]

If you don't make some end stops you will find the foam will give way. If you always fly and land well and have few midairs you may be fine. But I know from experience it's easier to fit them now than later. I used to consider the foam was good enough. It isn't. The rods do give a soft end stop because they are mounted in the foam. 

[satinet]

when I put the ballast tube in my m60 i just cut a slot the same size as the ballast tube in the wing.  the use a bit of sand paper on the tube itself. Sand the round in to a bit of balsa and glue it all back together as a sandwhich with the EPP top/bottom. That's how I remember the instructions anyway. It's EPP whatever you do you can put right with a bit off GG and filler!

 

 

the ncfm ballast tube came with plastic end stops so it wasn't a problem stopping the ballast coming out.

[Jerry Lunt]

Ballast tube and cut-out with slivers from top and bottom for capping it off.

picture on side because ******* camera thinks it knows best 

I tested the tube for perforations by putting an ordinary party balloon on the rough end and blowing it up, stick my finger over the square end and submerged tube in water.  Revealed one hole which I sealed with CA.  When I came to put the tube in I found lumps of epoxy on one side where it had run down before curing, so these were sanded off but I failed to check for leaks again, I thought it would be OK.

Tube installed and excess GG cut and sanded away:

but when I tried putting a slug in, found there was some extrusion of GG inside.  Fortunatey, only one little blob which I could reach to knock off with a screw driver but still the slug would not slide in freely.  Some sandpaper stuck to a piece of poly pipe using double sided tape soon removed the offending GG and Bob's yer Dad's bro 

Unevenness now sanded and filled with lightweight filler.

If I was doing this again, I think I would limit the ballast size to 10mm diameter.  12mm plus the tube thickness left little EPP above and below the tube.  Might have been better to cap this one with balsa sheet.

 

[Andy_B]

Carefull boys       youll be accused of building soon if you don't look out ................I might even make a new fuz for the Reaper

 

PS mike ..I like the idea of the hole in the servo box

[satinet]

I did rebuild my m60 a couple of months back. Flew it at BD, but decided <5mph at BD with a model covered in 175micron lam film wasn't a good combo after several walks to the bottom.

[isoaritfirst]

 

Fuselage sliced in half on the band saw and hole melted out for switch and battery.

Switch has charge lead installed alongside and is pushed through hole from underside, with a  foam chunk glued in beneath it, to keep it all in place.

Wing picture shows a square carbon tube installed between servo bays to allow wires to be fed through to fuselage and also

for them to be able to be pulled through to allow servo replacement.

Servo frame shows simple construction.

First make or find a piece of ply that is the same thickness as the servo. I glued a couple of pieces together.

Then I rough cut into a length slightly wider than I needed and about 8" long and cut out a U shape on each end. I used the band saw and  end stop just running the saw down many cuts to remove the material. Then cut off each U shaped end and repeated  so that I had 4 pieces.

They were glued onto the thin ply backing board with a gap for the servo lugs to fit into. Then outer edges were cut closer to overall size on the band saw and tidied up with a run around the belt sander. Hardly any measurements were taken just roughed out and sanded. All very quick. 

 

[Gromit]

 

Scram & Mike, great to see some building underway during this awful weather, keep the posts & pics coming please.

Mike Just like Andy, I like the hole in the ply servo mount to aid servo removal if req'd, i'l be incorporating this into future foamie builds.

    Stu.

[Jerry Lunt]

How are you holding the servo in the mount?  Just with the covering?

[isoaritfirst]

Servo frames are sunk very slightly in the foam so that a piece of ply or thin epoxy board can be fixed in place to hole the servos in. They are actually a tight fit and would work fine with just the models covering spanning acoss the hole.

[evad]

guys , when you get to the covering stage of your builds please post some detailed photos of the processes you are using , I'm still not sure about using laminating film as the cost for delivery is just ridiculous .... 

mike , did your fuselage come ready shaped , if not how did you get such a perfect looking shape to it  ?  

thanks , dave 

Edited December 20, 2015 by evad
another question asked

[satinet]

 

Here are pictures of my m60 and Hp60. I sold the hp60 a long time ago. Back when both models were made the perceived wisdom was to thinned goop some areas, fill the epp with spackle/light filler and then tape and then cover with film, which was how both of these models were done orginally.

However, the m60 as pictured is a recent recover. I removed all crossweave tape from the wing and covered with 175lam film, which hadn't been "invented" when the model was built orginally.  Because the model was made with spackle I needed a fair amount of '77 spray to get it to stick. After that I just covered it with pro film on the wing and fin, solartex on the fuselage and solarfilm on the ailerons. I didn't put a breather layer between the lam film and profilm and you do end up with a lot of air bubbles. 

For the recover I did quite a few coats of thinned goop on the fuselage followed by Xweave tape then solartex. Not sure thinned goop helps, but it seemed like a good idea.

in my experience with these models you don't want to put your aileron linkage all on the bottom of the wing as it tends to snap off on heavy arrivals.  Either put the linkage on the top skin or do a crossover linkage like a mouldie.

AFAIK, Steve drake models come with the fusleage pre shaped. The ncfm instructions tell you how to shape the fuselage. The weak point on the m60/moth is the fuselage, which quickly becomes squashed in the nose and if you crash hard the wing tends to blow out of the top of the wing seat. Mine has a second carbon spar over the top of the wing inside the fusleage. If i was building it again now I might consider routing a channel in the top of the fuselage and filling it with wetted tows. 

As I say squished noses are pretty hard to avoid. 

Even on bare epp I didn't think lam film stuck that well. I guess it would depend on the epp.  You don't need lam film for the models to fly well. The m60 was a good model before I crashed it in to the side of rushup hill DSing, and recently rebuilt as shown.

The HP60 I think held/holds the world DS record for that airframe built as described above, on the rc-speeds site (not flown by me!), and it was not built with any special modifications. I think that was around 160mph or so. The models are good stock or nearly stock.

[isoaritfirst]

Top half of fuselage stuck to part taped wing.

X weave on LE and TE and around tips. also taped around the wing centre.

Servo wires will be fed through to reciever in cut out in fuselage bottom piece.

 

Hole cut right through for reciever which is then glued into gap and a piece of EPP re-inserted with PU into underside of reciever.

Cut out piece will be alos inserted over reciever to fully encase it but it will allow the area to be removed if needed.

[evad]

Thanks for the information Satinet , My brass rod for the ballast arrived today , so hopefully I can move my build on again , if I can grab some time 

 

dave  

[isoaritfirst]

This video of my Bluto has a long section at the end detailing the build that may be useful.

Profilm over New stuff is easy if you cover with strips. 

Also stick it down with 77 spay smooth it with a credit card as you go, without stretching it. Then very gently activate its glue with very little heat.

Once its all down well you can add more heat if needed - but best not to. 

Run Diamond tape along the LE joint, or if you feel really brave cover with a wrap that has no joints on the LE (easier with stripes and some model shapes with straight LE.)