Chip Shop

[Martin McIntosh]

Thought I would put the full process on while I was at it since others may be interested. Now, just a few thousand to go.

[Martin McIntosh]

The rib tapes, dashboard kits and mini hinges arrived today from MRM, only ordered a couple of days before Christmas so super service and a good excuse to suspend riveting. Tapes fitted and the dash kits assembled. Good job that I did not drop any of the micro screws because there were none to spare.

Tried painting the undersides of the control surfaces with my usual Humbrol enamel but must have been using a duff/frosted tin because it refused to stir properly and even two coats did not cover so have ordered some Guild light grey. This seems to be rebranded Spektrum so should be OK.

Pics show my feeble attempt with paper ones then the proper jobbies. Sorry about the blurred photos especially the ones of the subject I shall probably pick, just photos of the PC screen.

[Martin McIntosh]

Geoff, just a bit more info. The glue I have used this time sets very hard, very quickly and the rivets have not sunk down as much as usual. Having been criticised on another thread for over prominent ones I have tried flatting some a bit with 400 grit used dry, then a light coat of paint to see what happens. They will probably require more flatting. You may or not be able to see in the pics the difference between the brown (flatted area) and the grey (unflatted).

[Geoff Gardiner]

Look good to me Martin.

I look forward to seeing what they look like with the finished top coat applied.

[Martin McIntosh]

Danny, if you are around and have a moment please. You said that your u/c failed because the fixing clamps bent a bit. I am about to install mine and fill in the surrounding area. My clamps are from 0.4mm brass but I have some rather heavy 1.4mm brass strip which I could bolt over the top of them. Is this the sort of thing you had to do to effect a repair?

 

Edited By Martin McIntosh on 06/01/2021 17:46:08

[Martin McIntosh]

Just removed the masking tape from everything and it looks OK. I gave up on the Khaki scheme because the paint in the tins did not even resemble the colour on the caps but luckily had two new 14ml tins of dark earth Humbrol enamel. I almost felt like Jesus with the two loaves and five fishes to feed the multitude when I had to eke them out but got there in the end. The green is Spektrum olive drab.

I could not find a full size scheme which really matched what I have built because they were missing the anti spin strips, had anti stall strips, rather different paint patterns or I could not get enough pics overall. One I picked was D-EFOM but later discovered that the underside is yellow, too late so this will just be a generic version with VT-CVT-X on it.

Lots of work still to go making seats and the vinyl masks for the lettering and decals. The bit I am not really looking forward to is glueing in the rudder/elevator hinges and joiner since this could be hit and miss and I only get one go at getting it right.

[Danny Fenton]

Posted by Martin McIntosh on 06/01/2021 17:44:53:

Danny, if you are around and have a moment please. You said that your u/c failed because the fixing clamps bent a bit. I am about to install mine and fill in the surrounding area. My clamps are from 0.4mm brass but I have some rather heavy 1.4mm brass strip which I could bolt over the top of them. Is this the sort of thing you had to do to effect a repair?

Edited By Martin McIntosh on 06/01/2021 17:46:08

Hi Martin, just seen this, sorry if it is too late.

I had mounted the brass strip wrong and the load could bend them, I reversed them and it was better, but really a rubbish solution, oleos clamped rigidly is the way to go. They flex no matter what you do. A design created before oleos were so easy to obtain.

Cheers

Danny

[Martin McIntosh]

Thanks Danny, I am not using oleos, just the simple torsion bars shown on the plan because of the difficulty in getting stuff at the moment. I shall fit the reinforcing bars because they will give peace of mind and are at least in front of the cg.

[Silver Wolf]

Hello Martin, below is my solution to the problem, at the finishing stage with my chippy. So at present untested but It worked well for a similar problem with an Astro Hog.

Slight deviation from the plan with regards the undercarriage. I have made P clips from brass and bushed the hard wood block with some brass tube

I mentioned in an earlier post that slight warp in one of the panels. I have since damped the panel and re-pinned flat to the board and it is within 1.5mm, so very pleased. I was a little nervous as the glue is not water proof and on another project found out that the wood only as to be damp!!!

Yours is looking good.

Kind Regards

SW

[Martin McIntosh]

Thanks SW, very similar to mine. I don`t think that things will bend very much now -

[john stones 1 - Moderator]

I remember thinking hmmm when building mine, that's looks fit for purpose Martin.

[Danny Fenton]

The problem is the entire leg flexes and bends backwards, driving the oleo fairing through the wing sheeting

I lost points at the Nats because I had to leave a gap between the wing surface and the shrouds.

My two larger Chippys have oleos and the shrouds can be fitted correctly, right against the wing skin.

Looking forward to seeing this Martin, should be a cracker.

Cheers

Danny

[Martin McIntosh]

I remember only too well what happened to my Chorus Gull when, on a fast landing, the torsion bars allowed the legs to bend right back pushing the spats straight through the wing underside. Reducing the length of the bars from 6" to 3" cured it. My 1:4 `Mew Gull` is built with 6g legs and short bars so I have used the same wire on this 1:5 Chippy. Yet to make the fairings but doubt if I shall cut the wing skin to clear them, I shall simply make them shorter.

[Martin McIntosh]

Having a go at the fairings and am attempting to use a thick walled carbon tube to simulate the oleos. I drilled out the centre and like a fool instead of splitting it tried cutting with my Proxxon. New blade now on order. The balsa halves have been made ready to fit and shall probably fix the whole things to the legs with silicone. A little litho round the `oleos` will not go amiss.

Since my chosen motor requires 20% nitro, fuel proofing is an issue, so following a recommendation on here I shall be using Rustins satin floor varnish which should be similar to the Sadolin gloss I have used in the past.

Just trying a bit on the ailerons and wing servo covers. It needs to be applied even faster than Tufkote so the large parts should be interesting to do. Spraying is out of the question in this weather.

I have also made a start on the roundels and fin flashes.Try getting round masking film on a very much curved fus. surface, more like an oval but I expect that you would need to be picky at the end of the day.

[Martin McIntosh]

Does not exactly convey my feelings because I found that I had started to do a fus roundel in completely the wrong size. I used my compass cutter on masking film and this time used the scale on it instead of measuring the radii with a ruler. I did not realise that the scale does not start at zero for some reason, so everything turned out at 15mm larger than intended. Stripped off the mask and started again but had already infilled the white and red bits with white, so too large now and will need to do some touching up later.

I have started to do the control surfaces with the Rustin`s varnish as above but this dries so quickly that even on these small parts it is a problem; it even starts to set very quickly on the brush. Adding a little of the supplied thinners helps. With hindsight I should have bought Sadolin PV67 in satin instead and may well try a test piece with the gloss version I have mixed with talcum powder, not tried by me before.

[Martin McIntosh]

Found twenty year old unopened tin of Solarlac flatting agent and found that this mixes OK with the much easier to use PV 67 so tried it on some test pieces. Fine at 5:1 but may need a little more.

Sneak preview of some decals done and in the midst of doing them. I had to cheat on the wing underside because I ran out of vinyl and masking to paint them on so they are just undersized vinyl from what I had left. I literally had to scrape the barrel for enough Humbrol white and Spektrum olive green to get this far: no chance of getting more at the moment with everyone either out of stock or wanting £10 postage for a 14ml tin.

[Martin McIntosh]

At last got to the stage when I can do a test assembly. Still work to do connecting up the rud/ele servos, adding the Rx, making up the wiring and Rx controlled switch for the lights, fixing the canopy in place ( I shall screw this on for now because the only pilot I could get is not worthy of his seat) and sorting out the cg which is 1/2" rearwards, but anticipating this I already have some more weight strips on order.

Talking of weight, if my luggage scales are to be believed it is, at the moment, 12lb 2oz (5.7kg) which is well within what I was hoping for and the chosen motor should be able to cope OK. Fus 2.6kg, wing 3.1kg.

Spent all of yesterday just doing the dreaded hinges. I can get the throws indicated on the Seagull instructions for their 80" one with the exception of ailerons which may be marginal but could cut down the top shrouds if necessary.

That needle valve would decide to protrude just at that awkward spot wouldn`t it?

I have omitted the cowl screws for the pics so it appears not to be in quite the right position.

[Geoff Gardiner]

That is looking 'mighty fine' Martin and the rivets have turned out well.

Is it all brush painted? My Hawk is ready for painting and I am debating whether to brush paint or wait until the spring/summer and spray paint (which I have to do outside).

[Danny Fenton]

Looks great Martin well done

Cheers

Danny

[Martin McIntosh]

Thanks both. I omitted to say that the cg was measured without batteries but a pair of LiFes are very light. The only ones I have which are not already spoken for are 700`s and would prefer 1100`s but not been available for a long time.

Regarding the paint, it is all brushed on including the clear lacquer. I think I said above that the neat Rustins dried too quickly to brush on so I reverted to Sadolin on the fus. I then tried the Rustins thinned 2:1 resin/supplied thinners and this looked good on the wing so rubbed down the fus parts and put a coat on top but it still looks a little shinier than the wing.

I did not find a pic showing any of the underside until it was too late but I shall not lose much sleep over that.

Surprising how that dark earth on the cowl is quite different to the rest despite the pair of tinlets I used being well stirred; not the first time I have seen this with Humbrol.

Geoff, my Hawk was sprayed with water based Ferrari red (big mistake using that). The Sadolin was also sprayed but ended up with a rough surface in places because my spraygun would not apply it quickly enough.

Long ago when I used to spray the original Tufkote on my aerobatic competition models I found that cellulose thinners would act as a paint stripper on overpainted bits so I would immerse the neat mixture in boiling water to thin it which was great.

When I came back to the hobby I tried that with the later Super Tufkote which immediately set in the gun. Ouch!

Rustins Plastic Floor Coating in gloss used with the correct thinners would, I imagine, spray fine but if you decide on this then try a test piece first. The thinners, available separately, may well work with Sadolin PV67 also.

[Martin McIntosh]

Nearly a disaster a couple of days ago just after I took the pics. The failover regulator switch I fitted was from an electric glider and reasonably well flight tested so I thought that I trusted it. However, on connecting the first battery there was smoke and melted wiring. Panic attack. Just the switch affected so I combed every site I could think of for a replacement, including placing wanted ads but to no avail so thought about pinching the one in my 1:5 Hurri but it has been lying in the garage for a long time so my Mossie became the donor along with its Rx.

I could have taken the pair of 1100 LiFe packs from the Hurri but ordered some NanoTech 1600s which arrived today. If fitted to the motor box along with the 700 lighting battery I reckon that the cg will now be correct since they are a lot heavier than the 1100s.

I would not normally consider Nanos again after a couple of lipos puffed after one light use as did nine of these purchased by a club mate, but since the chemistry and loading is quite different I am giving them a go.

Test filled the tank today and checked that the YS is pumping fuel through so will run it with the cowl off to start with when the weather allows. Other than that I just need to set up the control throws and screw the canopy on.

I expect this to then lurk somewhere for the foreseeable future. Now what?

[Martin Harris - Moderator]

OP number going in that handy hatch?

[Martin McIntosh]

Had not given that a thought yet. Thanks for reminding me.

[Martin McIntosh]

Pleased to report that in perfect flying conditions I plucked up enough courage to maiden it today. Went quite well but I do wish that I had given it (less if any) right thrust because it turned right under full throttle and left on idle which I can live with. Oodles of power from the YS 110. Not tried the flaps yet.