Logo
Builders' Plan Gallery  |  Hip Pocket Web Site  |  Contact Forum Admin  |  Contact Global Moderator
August 20, 2019, 06:23:30 PM *
Welcome, Guest. Please login or register.
Did you miss your activation email?

Login with email, password and session length
 
Home Help Search Login Register
Pages: 1 2 3 4 5 6 7 [8]   Go Down
Print
Author Topic: 1/18th scale D.H. 85 Leopard Moth  (Read 9881 times)
0 Members and 1 Guest are viewing this topic.
Prosper
Platinum Member
******

Kudos: 54
Offline Offline

United Kingdom United Kingdom

Posts: 1,416

Topic starter


Ignore
« Reply #175 on: November 12, 2018, 12:11:21 PM »

Picture 1, Nursing Sister: "Doctor! At long last the patient's sitting up and taking notice!" The landing gear is fixed but there are a couple of issues. At some point a few weeks ago I know that the struts would collapse into the ground position with very little pressure, and then spring into the flight position when the pressure was removed. Now, one of them jams. I don't know what's happened in the intervening weeks to cause this - mebbe it's just temp/humidity changes. It's not a problem - the strut has to be positioned manually, that's all - but I had thought it would be a nice touch if the struts extended when one picked the model up and compressed when the model was put down.

The other problem is potentially serious and is due to the fact that full-size aeroplanes are stressed to land whereas scale models have to be stressed to crash-land. The full-size LM has no forward/backward movement in the landing gear (why would it have?) but my model does. Pic 2 shows the spring (big arrow) and the gap between the rear struts and a fuselage bulkhead (little arrow). The gap is tiny. When the model lands the struts swivel back so either they or the bulkhead or both, could be broken or damaged. I twigged this back in the summer sometime but now I'm seeing it for real. The spring is fairly stiff and of course the struts all have a bit of give in 'em, so I hope the whole setup can mop up a good bit of shock without breaking. Maybe this is always destined to be a 'long grass only' model. . .

Pic 3 is the belly panel. This iteration is to be rejected (nasty wood) but will provide the template for cutting a better one.
Quote from: Prosper
To remove the panel I intend to shove a rod into one of the holes around the undercarriage struts and up to where it can bow the panel from the inside until it pings out at the front. "There is no Plan B"
Method tested. Method works.

Pic 4 shows the padded shoulders either side of the cabin top. I didn't make a very neat job of these but I'm letting meself off because fair dos, they were really difficult to cut, fit and glue into place. Perhaps I can clean them up a bit another time.

I've now got my first good weight estimate. The complete fuselage and tail surfaces inc. motor peg but without prop and noseweight will be about 16 ½ to 17 grams. I hope the wings won't be much more than 15g but that's vague because I can't guess the weight of the folding wing components. Unfortunately some back-of-a-happy guy-packet sums tell me that with a forwward CG, just balancing 15 gram wings might need 2.5 to 3g of noseweight, never mind balancing the tail.

Stephen.







Attached files Thumbnail(s):
Re: 1/18th scale D.H. 85 Leopard Moth
Re: 1/18th scale D.H. 85 Leopard Moth
Re: 1/18th scale D.H. 85 Leopard Moth
Re: 1/18th scale D.H. 85 Leopard Moth
Logged
strat-o
Gold Member
*****

Kudos: 7
Offline Offline

United States United States

Posts: 370



Ignore
« Reply #176 on: November 12, 2018, 04:04:38 PM »

Stephen, seems like this plane might do well as an indoor flyer.  Once trimmed, I've seen indoor aircraft actually land in lieu of crashing.

Marlin
Logged
Prosper
Platinum Member
******

Kudos: 54
Offline Offline

United Kingdom United Kingdom

Posts: 1,416

Topic starter


Ignore
« Reply #177 on: November 12, 2018, 04:49:03 PM »

That's an interesting comment Marlin. I've never flown indoor and I'm not likely to, but I've wondered about the landing business. It's not so much that indoor rubber scale models are trimmed to run out of turns just as they touch down - though that may be part of it - but it's the surface the model lands on. The surface is very hard but very skiddy. I should think that's a good bet compared to outdoor landings in which on most surfaces the model is arrested either instantly or almost instantly - in which case it has to take the ensuing tumbles. I think indoor the worry would be brick walls - and chairs, I think I've heard vilified also - the equivalent of sheds and trees, I suppose. The 'kwik-bilt' test model flew very tame circles once trimmed, in calm air.

Stephen.
Logged
Prosper
Platinum Member
******

Kudos: 54
Offline Offline

United Kingdom United Kingdom

Posts: 1,416

Topic starter


Ignore
« Reply #178 on: November 21, 2018, 01:44:02 PM »

There's only one photo here - I've got more to post but I'm trying to go over to Linux once and for all and haven't found a graphics program with anything like the speed and utility of my mid-1990s Paintshop Pro. And this 'simple' text editor is loaded with junk too.

Quote from: Prosper
At some point a few weeks ago I know that the struts would collapse into the ground position with very little pressure, and then spring into the flight position when the pressure was removed. Now, one of them jams.
I fixed the sticky undercarriage strut in the end. I had to bend the whole unit to near breaking-point to extract the inner strut from the outer - probably foolhardy but I got away with it. Then today I made most of the venturi; a new belly panel, and the fairings that sit on top of the upper shock struts to cover the 'rotating-strut' gear mechanism. Then slapped more silver paint on things.

I may have more modelling time in the offing what with the weather going downhill generally - but also I'll be spending time trying to obtain 'apps' that do what I want them to do in Linux.

Stephen.
Attached files Thumbnail(s):
Re: 1/18th scale D.H. 85 Leopard Moth
Logged
Mefot
Gold Member
*****

Kudos: 7
Offline Offline

United Kingdom United Kingdom

Posts: 293




Ignore
« Reply #179 on: November 21, 2018, 01:52:28 PM »

and haven't found a graphics program with anything like the speed and utility of my mid-1990s Paintshop Pro



Have you tried a programme called GIMP. I used it years ago before I could afford Photoshop. I suspect it has improved in the meantime  Smiley
Logged
Prosper
Platinum Member
******

Kudos: 54
Offline Offline

United Kingdom United Kingdom

Posts: 1,416

Topic starter


Ignore
« Reply #180 on: November 21, 2018, 03:20:36 PM »

Hi Mefot, thanks for the suggestion. I've used the GIMP for years too. It's good for a few particular tasks and much more 'powerful' than the pre-millenial Paintshop Pro but that also goes with more fiddling and faffing. The number of clicks to get that one measly photo ready to go on HPA is really ridiculous. Cannot save .xcf file. Must export. Cannot export transparency. Convert. Quality 90%. . .all this means clicks. It can't seem to save chosen resize ratios at all so more clicks per operation to resize the image. . .

. . .and why does it have to be reduced to 600 pixels width to get within the 400kb limit when Paintshop gets 1500 px width out of the same filesize? [rhetorical question, but if anyone does know the ansa, I'm just interested.]

Many people I've moaned to about such issues don't seem to see a problem. Do they prefer clicking mouses to building model aeroplanes?

Anyway I favour Linux in principle and do appreciate that this is all freeware.

Stephen.
Logged
Prosper
Platinum Member
******

Kudos: 54
Offline Offline

United Kingdom United Kingdom

Posts: 1,416

Topic starter


Ignore
« Reply #181 on: November 22, 2018, 04:12:12 AM »

Quote
[rhetorical question, but if anyone does know the ansa, I'm just interested.]
Okay, I am interested: Image resized to 1500 x 1125 px using Paintshop Pro = 185 kB; same image resized to 1500 x 1125 px using GIMP = 1.06 mB. Appearance is the same. What's going on there?

I stayed up late and found this current GIMP 2.8 less useful than the 2.4 I'm used to. I had a dekko at their website and it seems they're playing with the big boys now. Not for amatoors like me. Fair enough. I found a program called Pinta which does most of what Ps P does albeit less well, but it can't resize images economically enough for HPA thumbnails.

Right, back to Leopard Moths and Windows.

Pics 2&3 show the aforementioned fairings over the top u/c struts. Although these are less than 2mm thick I hollowed them out anyway - that 0.01g weight saving could be important, y'know Smiley. Pic 4 is the paper venturi, and pic 5 attempts to show how I made the rims or flanges at either end. I placed the paper cone on a non-stick surface and bled thin CA round the base - plenty of it. You can just about see the CA round the base of the cone. When this had cured I prised the whole lot off the non-stick surface with a razor and cleaned up the CA 'flash' surrounding the venturi cone, into what looks a bit like a flange.

How I'm going to fashion the central element and mounting of the venturi I don't know. It's about scale size but is just kind of generic in shape - I tried to make a steeper shorter cone at the front but couldn't do it.

Stephen.
Attached files Thumbnail(s):
Re: 1/18th scale D.H. 85 Leopard Moth
Re: 1/18th scale D.H. 85 Leopard Moth
Re: 1/18th scale D.H. 85 Leopard Moth
Re: 1/18th scale D.H. 85 Leopard Moth
Re: 1/18th scale D.H. 85 Leopard Moth
Logged
cvasecuk
Silver Member
****

Kudos: 5
Offline Offline

United Kingdom United Kingdom

Posts: 239



Ignore
« Reply #182 on: November 22, 2018, 05:48:21 AM »

I too still use PaintShopPro7 rather than more more modern programs but find it crashes if I use the mouse pad to zoom. If you do find an alternative which is as good please let us all know!
Ron
Logged
RalphS
Gold Member
*****

Kudos: 23
Offline Offline

United Kingdom United Kingdom

Posts: 806



Ignore
« Reply #183 on: November 22, 2018, 06:20:02 AM »

No problems here with PsP X6 running on W7.  To re-size Jpegs just needs Edit/Image/Resize and box comes up showing last size used. Just click and it is done.  No zoom crashing either.  I went to a series of talks/teach ins at out local Photo club - sorry.. Society.. to get to grips with the basics of digi processing and came to the conclusion that PsP gave 90% of PS at 10% of the price. Excellent program.

Love the Leopard Moth progress - I would want to put it in a glass box.  I saw a full size one over the Peak District last year when I was coming off Jacob's Ladder.  Unmistakeable plan view - sounded nice too.  Keep up the good work.

Ralph

ps. Just finished an all foam prepainted Ares Taylorcraft for micro radio.  Sussex Models was selling them off quite cheaply.  Everything held together with magnets. Didn't have to think about anything except to to get the rudder and elevator linkage the right length and the correct side.  Cheesy
Logged
Prosper
Platinum Member
******

Kudos: 54
Offline Offline

United Kingdom United Kingdom

Posts: 1,416

Topic starter


Ignore
« Reply #184 on: November 22, 2018, 06:49:46 AM »

Ron, Ralph, you boys are so with it, man - Paintshop 6, 7? Mine is v. 4.15 and isn't even the whole banana - it's a promo version  from a CDROM full of tat, from the days when you bought a computer magazine with a disc sellotaped to the cover Cheesy. As you say, resizing and saving is dead quick. It has line-draw which displays the pixel count as long as the mouse button is depressed which makes it really good for obtaining ratios from photos. It displays the ratio of selections, so you can f'rinstance crop a piccy to 1.33 to 1 without counting pixels. . .and it opens and works at light-speed. Sigh.

Stephen.
Logged
Prosper
Platinum Member
******

Kudos: 54
Offline Offline

United Kingdom United Kingdom

Posts: 1,416

Topic starter


Ignore
« Reply #185 on: November 25, 2018, 02:01:56 PM »

Quote from: RalphS
I would want to put it in a glass box.
I might do that Ralph - it would be fitting: this model's picking up plastic components so fast it's like an Airfix kit anyway Smiley. It's got more plastic than a Cirrus SR22 Cheesy.

It's been parky the last few days, and no sun to lob out a bit of radiant heat. Around 10 deg.  at my working table. I can only stick that for short periods these days. I wonder if the low temp caused the beading of the gloss varnish I sprayed on the Leopard Moth window frames? Pic 1 shows these [plastic Grin] items and pic 2 shows the one I sprayed months ago - the smooth lower one. For a while I thought I would just go with the wrinkly examples, but when I placed them on the LM fuselage for a preview, wrinkly next to smooth, it looked awful, so I'll have to make another attempt.

Re. the 'Chrome Pen' which gives this shiny metallic look: it's by no means a perfect answer to anything. The very uninformative (at least it was when I perused it months back) website, says "low abrasion resistance" or something like. That's a euphemism if you want one - frankly you can't touch a 'chrome-penned' surface, even delicately, without degrading it. Rub it and it's gone. It has to be sealed with varnish. I tried brushing varnish on, but that immediately destroys the chrome look. I got away with it once - IIRC I had a huge drop of varnish hanging off the brush and quickly ran it along a strip of chrome paint such that the bristles didn't ever touch the surface.

I struck out "paint" because I don't think this qualifies: I think they've found a way to suspend minute particles in solvent such that when applied to a surface the particles coalesce, the solvent evaporates and the surface looks like real, solid chrome (it is impressive to see). However, it needs covering with a sealant of some kind, and however glossy, that detracts from the 'real metal' look to some degree.

Furthermore, however clean and grease-free the surface, the chrome solution tends to puddle up due to surface-tension (like many paints do), leaving bare, uncovered circles here and there. Touching-up these bald spots immediately re-solves the surrounding area which can leave a curdled mess of ridges and dull areas. This pen can certainly do very useful and impressive things but is no doddle to use. It highlights even the tiniest specks of dust too. I think I'll be keeping it for little details like door handles. I also intend to get into the reservoir to try brushing it on.

Stephen.
Attached files Thumbnail(s):
Re: 1/18th scale D.H. 85 Leopard Moth
Re: 1/18th scale D.H. 85 Leopard Moth
Logged
OZPAF
Palladium Member
********

Kudos: 180
Offline Offline

Australia Australia

Posts: 5,045



Ignore
« Reply #186 on: November 25, 2018, 07:12:32 PM »

I was wondering Stephen if some small sort of warm spray box - (booth?) might help for spraying these critical paints? I was thinking of a open cardboard box with a incandescent low wattage lamp inside it?

I can imagine it's a wee bit annoying when what worked last time doesn't now.
Strife and vituperation or something Smiley

John

Logged
Prosper
Platinum Member
******

Kudos: 54
Offline Offline

United Kingdom United Kingdom

Posts: 1,416

Topic starter


Ignore
« Reply #187 on: November 26, 2018, 04:20:37 AM »

Good thinking John. If I'd had my wits about me I'd have at least used an electric fan heater to waft warm air about. I guess I wasn't expecting trouble. My spraybooth is normally 'The Planet', inasmuch as I prefer to spray outside, wind permitting. Some long time back I was doing some small spray job indoors - into a three-sided cardboard bunker, in fact - and the low sun happened to illuminate a cloud of microscopic droplets rising from the bunker and drifting very slowly round the room. I was very surprised that an airbrush with a 0.3mm needle/cone and about 20 p.s.i. would produce so much yuk. For little jobs like these window frames I hold my breath while spraying (indoors), and then 'step away' to where the air's cleaner.

I did in fact make a new 'hot box' a few months back, using a 60w or 100w incandescent bulb (hard to find nowadays - I believe you're sent to the guillotine if caught in possession anywhere in Europe). It operates between 40° and 70° and is for forming balsa/aliphatic sheet.

Stephen.
Logged
OZPAF
Palladium Member
********

Kudos: 180
Offline Offline

Australia Australia

Posts: 5,045



Ignore
« Reply #188 on: November 28, 2018, 06:40:35 PM »

Quote
I did in fact make a new 'hot box' a few months back, using a 60w or 100w incandescent bulb (hard to find nowadays - I believe you're sent to the guillotine if caught in possession anywhere in Europe). It operates between 40° and 70° and is for forming balsa/aliphatic sheet.

 Smiley
John
Logged
fred
Gold Member
*****

Kudos: 6
Offline Offline

Canada Canada

Posts: 486



Ignore
« Reply #189 on: November 29, 2018, 05:21:36 PM »

Said recycled Cardboard box... fitted  with a Cheap Bathroom vent fan..duct taped on even (as example)
using a bit of dryer duct as exhaust to a window opening.
Allows one to paint indoors (where cold wet breezes are absent )  while the exhaust arrangement  keeps much of the airborne filth out of one's lungs.
 Although Face filters are in plentiful supply.
Logged
Prosper
Platinum Member
******

Kudos: 54
Offline Offline

United Kingdom United Kingdom

Posts: 1,416

Topic starter


Ignore
« Reply #190 on: April 29, 2019, 05:19:15 PM »

This came out of hibernation a few weeks back, but while the grass grew the weather was almost totally unflyable, so there was  little incentive to push on with the model. And anyway, the grass grew too long to walk on while the wind blew. But today my neighbour mowed the grass - several weeks earlier than I'd guessed he would - and it suddenly seems that in three or four weeks the grass might regrow enough to allow test flights of this or that delicate model. I hope that if the Leopard Moth's sprung undercarriage works as intended, the model might be able to land on firm surfaces - but I'm not going to risk that until I'm fully comfortable with the model's behaviour, and that means long grass to start with.

Another drag was that the balsa/aliphatic sheet I made for the wings last year was heavy (reply #163). I buy balsa very infrequently but in goodly amounts, to last me three or more years maybe. The sheets of any given specification (light C-grain in this case) come from just two blocks because they're sawed to order. I believe the saw operator uses one block to push the other through the saw - thus keeping their hands safe - then grabs the emerging block and brings it back to push the other through, in turn, so there's a constant feed. If one of the blocks is bad then half your order will be bad. In this case it was nearly two thirds, I don't know why. So I'm instantly short of light C-grain, only weeks after making the order, and have a dead weight of rubbish wood, making the good sheets very expensive. I've used the &%%$ wood to make a couple of electric test models but it's no good for serious work.

Pic 2 shows wing blanks of the bad wood; it's not just heavy but bits of it are almost pith, right next to rock-hard streaks and furry bits (however much you sand the surface the fur is still there, and this isn't just a phenomenon that occurs at full moon) and holey bits where the pores are really wide and deep.

Never mind. In seeking to overcome the problem I tried a slightly different way of coating the wood with aliphatic. It has proved slightly lighter but more to the point, quicker and simpler. Necessity is the Frank Zappa of invention, as the old saying goes.

I hope to get re-enthused with this model if the weather improves.

Stephen.
Attached files Thumbnail(s):
Re: 1/18th scale D.H. 85 Leopard Moth
Re: 1/18th scale D.H. 85 Leopard Moth
Logged
OZPAF
Palladium Member
********

Kudos: 180
Offline Offline

Australia Australia

Posts: 5,045



Ignore
« Reply #191 on: April 29, 2019, 08:42:23 PM »

I'm sure you will find a "Zappa" way around these minor hassles Stephen.  Smiley What is that unusual truss assembly hiding next to the fuselage in the maintenance hanger?

John
Logged
Prosper
Platinum Member
******

Kudos: 54
Offline Offline

United Kingdom United Kingdom

Posts: 1,416

Topic starter


Ignore
« Reply #192 on: April 30, 2019, 02:13:59 AM »

Hullo John, the truss is the test lashup I made to test my idea for articulating and springing the undercarriage. It's facing backwards but if you mentally flip it round you'll probably see it matches the finished, installed u/c. I don't know why I kept it once the job was done.

Stephen.
Logged
Prosper
Platinum Member
******

Kudos: 54
Offline Offline

United Kingdom United Kingdom

Posts: 1,416

Topic starter


Ignore
« Reply #193 on: June 01, 2019, 03:51:08 AM »

Quote from: Prosper
In seeking to overcome the problem I tried a slightly different way of coating the wood with aliphatic. It has proved slightly lighter but more to the point, quicker and simpler.
Spoke too soon. Yes I've got the weight down; yes it's quicker and simpler, but after a week I saw that the grain was showing through again. Although I heat the aliphatic-coated sheets to about 60°  to cure them, and the material is fully workable after an hour or so, it evidently takes many days for all the water in the glue to fully evaporate = shrinkage = grain showing.

So, more testing.

Stephen.
Logged
fred
Gold Member
*****

Kudos: 6
Offline Offline

Canada Canada

Posts: 486



Ignore
« Reply #194 on: June 01, 2019, 02:52:35 PM »

Microwave does V quick work on PVA laminated Balsa.
 Dunno if appropriate to your needs.. But?
Logged
Prosper
Platinum Member
******

Kudos: 54
Offline Offline

United Kingdom United Kingdom

Posts: 1,416

Topic starter


Ignore
« Reply #195 on: June 04, 2019, 05:20:27 AM »

Thanks Fred, idea noted: microwaves 'cook from the inside'. It doesn't address the primary issue though which is grain showing on the surface of the coated sheet. I think I have made an advance with my 'speriments, but had better wait before I start crowing.

Stephen.
Logged
Pages: 1 2 3 4 5 6 7 [8]   Go Up
Print
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.21 | SMF © 2015, Simple Machines Valid XHTML 1.0! Valid CSS!