Learning to build in 1/87 scale

As you said, the picture says it all...

L.

I'm actually looking for very small electric motors, to see if it would be possible to motorize aircrafts as small as 1:87. I haven't found them yet, at least not easily and relatively cheaply available. Today's result is too big for 1/87, but would be good for ordinary scales - and it was cheap.

Like the hunt for hairdryer fan jet engines described in another thread, the flea market never fails. Today I found a small electric toy car of the simplest kind. For one euro, it was worth carrying home to see what was hiding under the plastic cover (photo 1 below).

A few minutes later, a pot of gold did certainly NOT reveal itself, but what was found was still worth saving (photo 2).

What I finally ended up with (photo 3) was a little bit more than the small 3-volt motor. From the battery case, a set of contact plates were rescued (might be good for glueing to a suitable card box within some plane), plus two springs (one never knows, maybe springs for some undercarriage some day, although the springs from cheap ballpoint pens are smaller and hard to beat).

Like I said, not a pot of gold, but still worth saving for a rainy day.

And I'm still looking for those VERY small electric motors...

Those little motors look great, Gil. And the price is just 5 dollars (if you can get them locally, that is), for three engines of varying effect:

[Blocked Image: http://RSK.imageg.net/graphics/product_images/pRS1C-2077891w345.jpg]

I do seem to remember a thread about vibrator motors, now that you mention it, but that was at least some years ago, or so it seems now.

Any idea at all about measurements, voltages, and such? Many thanks as usual. - Leif

Gil, you are not only a pearl, you are also a resourceful old pearl and the guardian of many pots of gold. Diameter 6 mm, I say! I might even have one of those in my mobile phone then, unbeknownst - after all, it does vibrate. In that case, the voltage should be something in the neighbourhood of 3,7 V.

Now at least I know what to look for. Perhaps one of the hobby suppliers here in Sweden will have something along those lines. They do seem to stock up pretty quick with the more toy-like gadgets (as apart from card models).

Many, many thanks, also from many others at this end, I'm sure. I wonder what the situation is like in Germany, for example at Graupner, or Robbe - anybody know something?

Leif

Jan - yes, it is a pager motor, turned toy motor; I just don't know where to look for one yet - haven't seen them at the flea market exactly... By the way, what kind of a pager are we talking about here, the kind everybody had in TV-series way back when, before mobile phones, or the kind of thing doctors still carry around - just so that I know what to look for.

And yes, the "Atomic workshop" certainly could keep one busy for a while. The motors seem kind of identical, right - diameter 7 mm. A bit pricey, though, at 15 dollars. Sure seems worth it with all those gears, and a prop too, if you're going to use it for flying, but not quite for just static display. Kind of overkill, if you see what I mean.

[Blocked Image: http://www.atomicworkshop.co.uk/Images%5CVoodoo15200150.gif]

A search for "Micro electric motors" turned up a massive result pointing at the source of all these little miracles: the workshop of the world, China, or in some cases Taiwan.

Many thanks in advance for the mail, Jan. Watching my letter box eagerly every day...

Leif

OK, Gentlemen. Thanks to your combined efforts, I will try to put together the lowdown of what you have supplied.

First of all, these two threads at Cardmodels.net (as mentioned by Gil) provide a world of links, leading to what comes next: "Power boosting" by Gil, and "Motorized models" by Fimdan.

Abstracting the most useful information from those, will get you to "American Science Surplus", and a couple of remarkable items. This one is called "World's smallest vibrator?" and costs 4 dollars:

[Blocked Image: http://www.sciplus.com/itm_photos/34568.jpg]

And this one is entitled "World's smallest motor?", at just 3 dollars (measurements in both images are in inches):

[Blocked Image: http://www.sciplus.com/itm_photos/33348.jpg]

And there's even a suitable power source, of matching size (or smallness!):

[Blocked Image: http://www.sciplus.com/itm_photos/31666.jpg]

It is entitled "Tiny NiCad", and sells at a reasonable 4 dollars. Measurements given are roughly 30 x 15 x 9 mm, if I've done the maths correctly in my head. This is still a little bit on the large side, and also a bit overkill, I think.

But it gets better! Here's an article from the Fine Scale Modeler Magazine detailing step-by-step how to motorize a 1/72 scale plastic model of a Spitfire using parts like (but not identical to) the ones above:

Below I have attached the full original article in pdf-format (also available directly from the source here).

Anybody at all interested in this subject, do read this article! The gist of it is that the author used a 1,5V pager motor from American Science Surplus for 3 dollars (see above), plus a common 1-cell battery of the type found in clocks, calculators, etc. The battery was mounted in such a way that it could easily be ejected downwards by pressing the antenna mast downwards. Slightly less pressure on the antenna mast just closed the electric circuit and made the prop spin.

This, I think, is appropriate technology, and the real pot of gold at the end of the rainbow. No overkill here - of course, find a way of replacing a cheap battery, instead of going for the recharging option (as I have done until now). And keep it simple - no need for extra switches and complicated soldering, except perhaps to the motor and connecting strips to the battery (no problem there).

Gil, Jan, I thank you both (and other friends at Cardmodels.net) for leading us here.

After this, we don't really have any excuse for not trying it out on a paper model as well, do we? (And I'll be hunting for pager motors from now on...)

Less than two dollars for this:

[Blocked Image: http://www.goldmine-elec-products.com/images/G12809B.jpg]

And it works on anything from 1 to 5 volts. 15 dollars for ten of them, might be the way to go, considering freight, etc., if you really decide to buy from these people. Jan, how about a collective order from Kartonbau.de, a la GPM and others?

It sure is getting better, and better, Gil! But I've got to tone done expectations of making paper models fly, particularly small ones - the old truth still holds, I think, that the density of paper is too large, versus its structural strength, compared to balsa, depron and other recent exotic materials.

But using paper models to provide the final cover of such a model (depron, etc), still is a very attractive idea (although the cut-out pattern would have to be reproduce on some kind of light-weight adhesive film, so the "paper" link by then would have become kind of ephemeral).

But let's dream on, by all means. After all, I've seen people flying RC stuff in the park outside which they carry around quite carelessly as toys while the baby sleeps in the pram next to them, whilst I tend to regard them with awe and more like the eighth miracle of the world...

Leif

OK, guys, so I checked out the particular pot of gold recommended by Gil, the Electronic Goldmine, and its page for DC motors. You should do the same! In there I found many interesting (and cheap - how do they get the prices down to this level?) motors, among them this and this:

[Blocked Image: http://www.goldmine-elec-products.com/images/G15615B.jpg][Blocked Image: http://www.goldmine-elec-products.com/images/G15768B.jpg]

It says it is the smallest motor they've seen, and that it is ideal for making small robots (I'm not familiar with that particular type of toys, but obviously you can use it for hobby purposes).

The point for me is that the diameter is just 4 mm, which would make it possible - just as an example - to get the props spinning on a 1:87 version of Jan Müller's DH88 Comet. I have not found any other motor (including the ones reviewed above so far) which would fit into the Gipsy-six engine nacelles at this scale. But this would!

Runs on anything from 1,5 to 3 volts - and you get two of them, brand new, for a dollar!

Now, there's an incentive for a common Kartonbau.de order, Jan!

For other purposes, like ships and aircraft in larger scales, there are a multitude of alternatives (all cheap). Just one example:

[Blocked Image: http://www.goldmine-elec-products.com/images/G15601B.jpg]

This is a small, German made, geared motor with a diameter of 16 mm. Says in the text: "We connected this up to one CR2354 coin battery and we could not stop the shaft with our fingers. Gearhead has a 76:1 ratio. Iron core motor is very efficient - current draw at 3VDC was only 21mA. This is the best, high torque gear motor for its size that we have ever offered."

Jan, if you let people have a look through the alternatives at the page above, perhaps quite a sizeable common order might be placed? I'd be in the market for let's say 10 two-packs reviewed above (just to be on the safe side and have a supply at home - it's not as if they would take up much space...)

Leif

Glad tidings for all of us in Europe - I've found a high-quality European supplier of 4, 6, and 7 mm diameter pager motors. It is the Swiss firm Didel. Have a look at their supply of pager motors here (scroll down past the cogwheels if you don't see the motors immediately).

Here are the three 4 mm diameter variants:

[Blocked Image: http://www.didel.com/microkit/pricelist/images/Mk04S.jpg][Blocked Image: http://www.didel.com/microkit/pricelist/images/Mk04.jpg][Blocked Image: http://www.didel.com/microkit/pricelist/images/Mk04L.jpg]

They are 8, 11, and 14 mm long, respectively. Each of them comes in variants for 1.2 volts (all of them) or 3 volts (the smallest one) and 2.4 volts (the two larger ones). In addition, as you will see, they have a wide assortment of "larger" (all of 6 and 7 mm diameter!) motors.

Three euros a piece, minimum order of 20 Swiss francs (which means at least five motors). Not unreasonable at all, considering the mass of complementary details they carry, and the documentation on their website. See for e.g. the very complicated specifications sheet and the tips on how to insert gears (and how not to do it; sensitive stuff these little motors!).

An advantage of chosing the longest motor would be that the shaft appears to be longer, which would make it easier to attach a tube to make it longer (this is still necessary; I've just checked my 1:87 drawing of Jan Müller's DH88 Comet, which I use as a reference for this little study in possibilities).

Next search thus would be for tubes with an inner diameter of 0.7 mm (the most common shaft diameter of these little motors). Didel also carries rivets of 0.76, 0.80, and 0.94 mm diameter (one of them possibly with an inner diameter of 0.7 mm?) which might be the solution to this problem. Hope so. In any case, I'm sure they'll answer a mail request for advice, eventually.

With these high-quality motors available directly, and at such reasonable prices, I don't really see a need for finding and operating on used cell phones. But if you happen to have one and want to try it (I would, if I had one on my hands), here's an important tip on how to get rid of the assymetric weight on the axis:

See David Cook's "Robot Room", with detailed instructions for how to use a vice, or a pair of locking pliers, in order to deform the weight slightly (attached photos).

After that, they seem to slip off quite easily (by hand). If not deformed, they will not budge. Whatever you do, don't try to just pull the weight off - you'll destroy the motor, since they are very sensitive to axial pressure.

This is indeed a wonderful new world opening up, also for card modeling!

Leif

PS. Going through the Didel website from their portal page I found links to an electric power model airplane weighing less than 1 gram (sic!), and a R/C helicopter weighing 3 grams (sic!!!). I won't go there anymore, or I'll get terminably diverted from card modeling - which is neither my intention nor wish.

I'm posting this addendum just in order to save (and share) the information as I get it and digest it. In this post a few caveats and misgivings - but also a promising new source:

1) The Swiss company Didel (above) truly seems a great place. It is an offspring of a research institution. But I am a bit wary of their present status, since their webpages haven't been updated for at least a year, and many pages are much older than that. Are they still in business? We will see.

2) The US firm Electronic Goldmine (reviewed before that) does not ship to any other European country than Switzerland and Norway (!) - not Sweden, not Germany, not Britain - and no exceptions. So count them out, unfortunately (if you do not live in Switzerland or Norway).

3) However, there is a US firm which ships worldwide, accepts paypal, and have VERY reasonable shipping costs (the same internationally as in the US, which is unusual indeed). Here's the lowdown:

Name of firm: Pagermotors.com. Freight: around 3 dollars (for purchases 10-50 dollars). See their low shipping costs here.

Have a look at their pager motors here. As you can see, the offer is much more limited than sources reviewed earlier. But they do have a 7 mm motor - and a 4 mm motor! (Don't be distracted by the removable attachment clip):

[Blocked Image: http://www.pagermotors.com/index_files/Products/7mm_NW/7mm(NW)_s.jpg][Blocked Image: http://www.pagermotors.com/index_files/Products/4mm_NW/4mm(NW)_s.jpg]

To the left is the 7 mm Namiki Pager Motor, with the eccentric conveniently removed. Price: 1.50 dollars each.

Data: 7 x 19 mm overall. Runs on 1.3 volts, 70 mA. Shaft diameter 1 mm (0.98). Free shaft length 5.4 mm. See also technical file (pdf)

To the right, the 4mm Namiki Pager Motor, also with the eccentric removed. Price: 2 dollars each.

Data: 4 x 16 mm overall. Runs on 1.3 volts, 70 mA. The body of the motor is flattened, so there are actually two diameters, 4.2 and 4.7 mm. Shaft diameter is 0.8 mm (0.78 mm). The downside is that the exposed shaft is only 2.3 mm, so attaching a longer shaft will pose some difficulties.

But perhaps that won't be necessary! From the technical file (pdf) I got the drawing attached below. From that, you can deduce that the engine house proper is 10 mm long (well, 9.9), and that there is a rather long (ca 3 mm, which is long, at least in this context) extra bit of covered shaft before the 2.3 mm free part of the shaft. This feature might even be turned into an advantage.

Perhaps it will be possible to fit the motor in the fuselage of the model, while the extended housing goes neatly through the front part of an engine nacelle, and the prop attaches directly on to the shaft. Much easier - and 2.3 mm is ample space for a prop in 1:87!

I will use the drawing and overlay it on some 1:87 planview of models, and get back later. This is just an interim progress report.

I have copied and redrawn the Namiki 4 mm motor, and superimposed it onto three different plan views of models which have been test-built or reviewed in this thread, plus Jan Müller's DH88 Comet, which I have used privately (on the drawing stage) as a test for trying out the small pager motors.

Starting with the DH88 Comet, the Namiki motor will be just right. See the first of the attached images below.

It will even fit into the Cessna 140, built so beautifully by Gil - although it will be tight, if you wish to incorporate a full cockpit. The lead wires will just about touch or even go through the instrument panel. But I think it might work - if only just. (For a review, and Gil's test build, see this post; and the finished model here.)

The PWS-50 which was reviewed and built earlier in this thread will be difficult - but not at the point I thought the difficulties wold occur, namely the front of the engine nacelle. The fit there is rather perfect, in fact. The problem arises in the cockpit area, where the motor will make it kind of difficult to move the control column for the pilot and passenger.

In any case, I am pleased with the result on the drawing board. Pager motors of this kind clearly can be used for 1:87 scale builds.

On larger aircraft, such as B24, B17, Catalina or the whole row of radial engine WWII single engine aircraft, there will of course be no problems at all.

An interesting point is whether the motor would accomodate a WWI rotating engine plus prop. I tried it out on Eric Johnson's Sparrow model reviewed in this thread, and as you can see from the last image, I think it will work just beautifully. Of course, the whole engine should be glued to the prop, and the entire outfit made to rotate, just like the real thing.

PLEASE NOTE THAT THESE ARE NOT THE ORIGINAL VERSIONS OF THE MODELS. THEY ARE ALL SCALED TO 1:87 (sometimes from 1:33, sometimes from 1:72).

Do click in the images and have a look at the full-size drawings. The four individual ones are scaled to a common size, roughly twice real size (at least on my screen), to enable a closer study.

The last composite has been reduced to a size which on my screen shows up in roughly real size. Goes to show what small sizes we are discussing right now!

Michael, about the razors - yes, the thought has struck me, too, and I have glanced many a time upon them in the supermarket. But at 9 euros a piece, and just to find out, no thanks...

Meanwhile, good news from Didel in Switzerland. They are indeed in business, and can deliver most of the small motors described at the top of the page.

The administrator and researcher there, Jean-Daniel Nicoud, much prefers to work creatively, he says, than updating webpages. However, everything available is listed in an Excel sheet which can be downloaded from here.

It is really quite ingenious, since you just tick of how many items of what you want, and it will calculate the price including freight and convert to euros from Swiss francs. Then send an email to Didel (info@didel.com) and attach your filled-in Excel sheet.

In order to know what to order, you should of course have the Didel webpage on pager motors open.

At the moment, I am trying to find out from Jean-Daniel whether it is possible to attach a small scale paper prop directly on to the motor shaft, and whether there are rivets which could be used as shaft extensions. Jean-Daniel seems a bit hesitant and recommends pinions and gear boxes, but that's for real flying models I think and hope.

Leif

I'm using the thread to think aloud, in order not to forget:

1. Pondering the problem of making the propeller shaft longer (if it really turns out to be necessary), I now think you should go for the simple solution: Roll a thin paper tube around a pianowire with the same diameter as the shaft (0.6 or 0.7 mm, or close to that). Incorporate the wire in the paper tube, except for the last 3 mm, which forms a sleeve to glue on to the motor shaft.

Glue the propeller to the paper shaft (or make it around the shaft as an integral part).

The tricky bit will be to align it properly, so it doesn't wobble. These little motors are likely to want to turn out some 6.000 rpms, and they shouldn't be forced to work at much less. Perhaps you will have to make a small bearing (a piece of nylon RC control rod)? In that case the shaft extension could be made of your standard 0.75 mm pianowire with the propeller glued at one and, and a paper sleeve connecting to the motor shaft at the other end.

Or perhaps a piece of suitable wire insulation, to double as a flexible coupling? In that case you need two bearings, which is too complicated.

2. What I'm thinking most about now is how the small battery cells (1.5 volt silver iodide clock batteries most likely; can be purchased for some 2 euros a piece in many sizes) should be mounted best - and simplest - in order to be able to change them; and how to design the simplest "switch" which can be manipulated from the outside without destroying the appearance of the models. Not every model has an antenna post mounted as conveniently as the Spitfire...

Leif

First @ Michael: Yes, you are saying in the clearest possible way what I was trying to get across. Thank you! (Although I was thinking about wire insulation instead of rubber hosing - difficult to find rubber hoses with an inner diameter of half a mm or thereabouts.)

Now for today's business: I have found what might be a very viable alternative to small clock batteries, namely rechargeable capacitor cells (which are also used in some solar-powered watches; I had one, but forgot all about it).

I was going through the US Pagermotors site again, more or less idly. By going to their site map page, I accidentally found a page on rechargeable polyacene capacitor cells. Here's what they look like:

[Blocked Image: http://www.pagermotors.com/index_files/Products/Electronic_Components/Polyacene/Polyacene(L).gif]

And here's the data: Data: Voltage Rating 3.0 volts. Price per unit: $1.10. Dimensions: 9.3mm (diameter) x 2.3mm (thickness). Capacitance 0.6 Farad. Internal Resistance < 20 Ohms. Weight 0.454 grams.

Comments on the site: "These tiny batteries can be charged and discharged over and over with little to no noticeable loss in capacity. Some people have successfully replaced the bulky capacitors in BEAM projects with these batteries. For more power, try wiring multiple units in series or parallel. Two batteries wired in parallel will provide adequate current for most Photovores and Solar engines."

Now, Pagermotors.com obviously is a site and a company which (like Didel in Switzerland) is maintained with no small amount of idealism. Compare for their links to university workshops and other projects. And for their low prices and civilized rates of shipping (2.50 dollars for orders under 10 dollars; 3 dollars for orders 10-50 dollars!).

It seems that two cells in parallel would be able to drive a Namiki motor. Or perhaps only one cell would suffice? I have written to the administrator, Fritz Meitzen (fritz@pagermotors.com) to enquire, and I eagerly await the answer.

If this is feasible, it wold provide the ideal solution. What we want is not something that will make the prop turn for an hour or even ten minutes, just something that will make it go for a minute or so.

Recharging lead-outs are much simpler to build into a small model, than a detachable battery option. Recharging could probably be made by two common 1,5 volt batteries in series. And the rechargeable cells are actually only half the price of a non-rechargeable clock battery.

If this works out, a complete outfit would be: One pager motor (2 dollars). One rechargeable capacitor cell (1.10 dollars). Freight (less than 0.90 dollars, spread out over an order of 4-5 units). Total 4 dollars, 3 euros. And if two cells are required, the total will still be around 5 dollars only per model. Quite acceptable!

Waiting for an answer to my inquiry, I give you a larger image of the 4 mm Namiki motors, just to enable comparison with the 1 cm capacitor cells (measurements on the ruler is in mm, which again brings home the small sizes we are dealing with here):

[Blocked Image: http://www.pagermotors.com/index_files/Products/4mm_NW/4mm(NW)_L.jpg]

I'd just like to report that Fritz Meitzen at Pagermotor.com has responded to my enquiries in a most friendly and encouraging way. He even offered to send a few parts of my choice free of charge for testing. So I've gratefully indicated a 4 mm Namiki motor and two of the rechargeable Polyacene capacitor cells.

In his mail, Fritz Meitzen is a bit dubious as to the running time of the motor if powered by two of these cells. "You can use the Polyacene batteries to run the 4mm Namiki motors. However, I do not think that the charge would last that long. Two batteries wired in parallel will usually discharge completely in a matter of seconds. [] You can charge them with a standard AAA battery or use solar cells."

(I should say that Fritz Meitzen is also running the Flexsolarcells site, similar to the Pagermotors site. Very interesting - look it up!)

Waiting for the trial parts to arrive, I could not help trying to calculate how many seconds "a matter of seconds" might imply. Refreshing some faint school learnings with Wikipedia information, here's how it goes:

Data for the polyacene cells indicates a capacitance of 0.6 Farads at 3.0 volts. Inserting this into the formula for Farads, we get:

Farads = Coulombs / volts

0.6 = Coulombs / 3.0

Coulombs = 0.6 x 3.0 = 1.8

Coulomb is the total amount of "electricity" the capacitor will store. However, chances are that the little Namiki pager motor will stop operating at around 1.0 volts, so there is probably only 2 volts x 0.6 Farads = 1.2 Coulombs to be had out of it.

How long will this suffice? Checking the current draft for the Namiki motor, it is given as max 120 mA, that is 0.120 Amperes. Putting this into the formula for Coulombs we get:

Coulombs = Amperes x seconds

1.2 = 0.120 x seconds

Seconds = 1.2 / 0.120 = 10

Now this is for one cell, at maximum current draft. If we use two cells in parallel, the worst outcome will be 20 seconds, and if the current draft diminishes as the voltage goes down in the capacitor cells, the running time will be slightly longer, although at lower rpms. Perhaps as much as 30 seconds can be had out of one charge?

30 seconds running time for demonstrating that the prop really moves at high speed in a 1:87 scale little aircraft, that isn't too bad, is it?

And it could get better - if your model is large enough to incorporate the 7 mm Namiki motor, it draws only 70 mA, which would mean a running time of at least 35 seconds on two cells in parallel (compared to the 20 seconds for the 4 mm motor), and probably some 50 percent more, or 50+ seconds.

Next on the agenda: Design a SIMPLE on/off switch, and recharging socket, using as few sophisticated parts as possible. I am thinking needles, connecting wires which are there in any case, and holes in the paper framework of the aircraft. On the outside, nothing more than three small pinpricks of holes should be visible when the model is displayed.

Until then, Leif

First @ Michael, and the idea to skip batteries and have lead-out wire for the motor through the wheels to a battery box:

What an ingenious idea! And it would clearly work, as demonstrated by the attached three-view of the little PWS-50 free download from Modele Kartonowe, which I already test-built in 1:87 (see this post).

However, I am too fascinated by the idea to mount an onboard "fuel supply" to abandon it totally yet (and it could still be combined with Michael's idea). For a drawing-board test, I chose the PWS-50, because that was the model where it seemed most difficult to get the parts in, due to its small size (see this post above). The attached three-view demonstrates the difficulties, but it seems just possible.

The basic idea is to mount all parts on a common fuselage keel, running from front to back. This keel would be multilayered, and incorporate connecting wires inside, between layers, much like an etched board in electronics (and there's an idea for you - make the keel out of an etched board - but now we are dreaming...).

This would enable "channels" for pins inserted from the bottom up into the center of the keel. Two of these little pin-prick holes would be for the charging socket, and they should be placed so that the aircraft could be stuck onto this socket and remain in balance there. Thus you could run the motor directly from the charging socket, serving also a display stand (a little like Michael's idea).

The charging socket thus would serve as a "universal" display stand for similar models, which is why some care must be devoted to creating a good standard (distance between pin-prick holes, polarity, etc.), suitable for all your prospective models to come.

The on/off switch would be a third discreet pin (entirely removable if you wish), stuck into a position not interfering with the charging socket/display stand. Perhaps from the top or bottom just aft of the cockpit.

I realize this might be difficult to envisage from a description in mere words. I'll work on the idea some more, and get back eventually.

Meanwhile, I have not had any further response from either Didel or Pagermotor.com, so we'll have to wait for what develops.

PS. The little steel-ruler measure in the three-view is courtesy Jan Müller - many thanks Jan! If anybody wishes to have one handy to incorporate into drawings, I attach a 300 dpi resolution pdf of it below. Enjoy!

PPS. I edited the steel ruler file so that it now contains two versions, one full size ruler, and one cropped, like below. Both are lighter and better visible. The file is also smaller - no layers.

That is so great, Gil! I was playing around with that a while back as well, and we will have to get back to it. We need a couple of good pilot figures!

While redrawing some figures I couldn't help put faces on them as well. I used one of the layer mixing techniques in Photoshop, but I plump forgot which by now.

I'm not saying who's faces we are barely seeing here, but they are quite prominent on the the site...

This is fun, isn't it.

I'd just like to report that Fritz Meitzen of the Pagermotors and Flexsolarcells sites wrote this to me yesterday:

"Your order will ship out tomorrow [last of August] via Airmail. I threw in a couple thin film solar cells as well."

Which means that shortly I'll be able to demonstrate my own photos of these little gems. And I'll start thinking about a solar-cell demonstration stand for small aircraft models, with their props rotating as soon as the sun shines.

Just to report that I'll be away this week, when the motor, capacitors, and solar cells are due to arrive from Fritz Meitzen at Pagermotors. There will thus be an interlude in reporting.

My wife and I are going to Germany, Brandenburg and Berlin area, but unfortunately no time for contacting friends, since this is a Church group event visiting our German counterpart parish, and the agenda is very full.

Leif

I'm happy to tell you that when we woke up up today, after returning yesterday from a very full and satisfying week in Germany, the long-awaited envelope from Fritz Meitzen and his Pagermotors conveniently arrived in the mail!

The contents were truly wonderful - two small motors, four capacitors, and two solar cells. It will be a great challenge - gladly undertaken - to find a way of working these small wonders into 1:87 paper models of aircraft.

Meanwhile, here are some pictures, to give you an impression of how absolutely wonderfully small these parts are (the model is the PSW-50, scaled to 1:87, and the figures are 1:87 from Preiser):

Acting on a tip by Ober Freak (in Martin's ongoing thread on the P40 Warhawk build) I found a free model of the Curtiss SB2C Helldiver by "Matt77". The paintwork of this model was so attractive that I went to work rescaling it to 1:87, rearranging the parts, and adding a good 3-view drawing of the original (also scaled to 1:87).

You can see the result below, and I have also attached a 7.6 MB pdf of the now 2-page 1:87 model. (Use the pdf, and not just the attached images - these are illustrations of lower quality and they are not to scale!)

In the course of the work, a couple of obvious faults in the original model were amended. The conversion process was not as easy as it might seem. Therefore I have detailed the different steps in a separate post immediately below, since it might be a good example of how to go about rescaling of models generally.

The scale of the original free model of the Helldiver was stated as 1:72. This, however, was obviously wrong - at least in the 72 dpi version offered at the site. The author must have worked in quite a different resolution, and then just saved it as a "web ready" image. This will automatically change the resolution to 72 dpi, and thus spoil the scale.

Since there was no way of knowing the original resolution, a little bit of detective work was necessary. The first step was to ascertain if the instruction drawing was to the same scale as the parts sheets of the model. This was quickly confirmed by copying parts of the canopy and superimposing on the three-view.

The fit was excellent, and the scale thereforedeemed to be the same. This would make it much easier, since now a side view from a three-view drawing of the original could be used for comparison to arrive at a correct scaling factor. If this would not have been the case, some large part like the wing can be used for matching to a drawing of the original, scaled to 1:87.

Next step: Find a good three-view drawing, plus the dimensions (span, length) of the original aircraft. A Google image search will always turn up at least something, although you may have to look through many pages of thumbnails of photos before you arrive at a good three-view. In my case, it came by way of Google from the Airpages.ru site. The otherwise excellent and reliable site by Richard Ferriere could not help out with the Helldiver.

Once you have a good three-view drawing, you can use information about span & length of the original to scale the drawing to 1:87. Figures of the dimensions of the original will almost certainly turn up as you look through your Google search results. Otherwise, search Wikipedia or one of your favourite sites for aircraft references.

When you scale your three-view drawing, be sure to change the resolution to your prefered working resolution (in my case 300 dpi). Do the same with copies of the original downloaded model pages.

Once you've got that right, you can copy for example a sideview from the three-view 1:87 drawing and superimpose it on the parts sheet. Use the magic wand to clean up all white areas of both the drawing and the model, so you can see through the layers. Now it is all a matter of resizing the parts sheet so that it fits perfectly with the 1:87 sideview from the drawing. Note the resizing percentage, and apply it to all copies of the download.

What you've got now is copies of the original download, at your prefered resolution, and scaled to 1:87. From here on in, it is a matter of taste how much you want to rearrange the parts. In my case, it proved possible to get the instructional sketches from the original plus the three-view drawing into a single A4 sheet, which is kind of nice.

Likewise, it was possible to fit in all parts (from originally two pages) into a single A4 page, which is also nice. The result is that a 1:72 original in four pages were fitted into two 1:87 pages - with a full extra 1:87 three view of the original included.

The last bit was about amending some obvious mistakes in the original. The right-left designations for the wing attachment points on the fuselage had been mistakenly switched by the designer, and the position of the red mark for the tail wheel was off center. These small details have been corrected in the download above.

As for the model, it lacks formers except for the engine dummy. It also has no cockpit interior, although it would seem quite possible to design a simple cockpit for pilot and observer. This, however, will have to wait. For now, a high-quality version of a good model is available at a clearly stated scale. If you wish to rescale it slightly up, or any amount down, you should feel quite confident to do so.

Many thanks to the original designer, "Matt77"! And I will of course welcome questions and discussion of the method outlined here. ( As always, German is just fine.) I realize that there are many intricacies at each step which might remain unclear. If so, it is better to respond to specific questions or suggestions.

Leif

PS. I just noticed that there is another similar fault in the original model. The left-right designations for the stab parts ("t lx" and "t rx") should be switched. However, I won't upload new versions at the moment, since the upload time is so long. Nobody is likely to mount the stabs upside down or backwards anyway. And, unlike the wings, there are no markings on the fuselage to confuse inexperienced modelers.

Studying the drawing of the SB2C Helldiver, side by side with the model, I found a discrepancy - the model had a four-bladed prop plus a large spinner, while the drawing had a three-bladed prop and a large spinner as well. Nothing too mysterious so far.

But looking up the Helldiver at Airpages.ru site, I found a companion drawing to the one I had used. As it turns out, the version I had originally found a drawing for was the SB2C-1, while there was also a drawing of a SB2C-3 - and this had a four-bladed prop, but a small spinner. (See attached images 1 and 2 below.)

To make things worse, the SB2C version Matt77 had modeled seemed most of all like an SB2C-4, depicted under SB2C-3 (see image 3 below). And the photos accompanying the two (or three) different versions clearly was a SB2C-1 (three-bladed prop, large spinner), although it was listed in the caption as SB2C-1 at the first listing and SB2C-3 at the second.

Trying to get a bit further to the bottom of this I searched Aerofiles for the different SB2C versions. It turns out that there were a couple of more versions, but that the SB2C-3 very well might have had a four-bladed prop, too, and a large spinner. (See image 4 below.)

So I'll settle for the version being modeled being either an SB2C-3 or -4. They may have been similarly outfitted with four-bladed props and large spinners (plus other variants as well, I imagine). And the drawing of the SB2C-1 is still the closest to the modeled version, since it has the large spinner - just think of a four-bladed prop instead!