1/18 scale Bölkow Bo-102 Helitrainer scratchbuild model

In my previous WIP article about the /18 scale Jukka Tervamäki Engineering JT-9T autogyro project, I explain in very detailed manner, how to build a vacuum forming device, starting from scratch and using materials that can be found in your local super market. If you are not aware how to build a scratchbuilt vacuum form, please feel free to read it as I described and it might be useful for you.

Heat your electric oven to some predetermined level, whatever works and start heating the plastic sheet. I have never tried this with a gas one, so use caution if you do! Once the plastic gets warm, you’ll notice it will droop down. When you think the plastic is soft enough, fire up the vacuum cleaner, take the plastic from the oven and thrown the sheet on the vacuum former. The plastic will nicely form around the moulds. This will take some practice and sometimes a mould tips over or the plastic won’t form properly over the mould (folding around edges). This is also the part where I should warn you that you can burn your fingers - I highly recommend Nomex Aramid flame resistant MilSpec gloves, which I personally use for the job. I buy large plastic styrene 50x30cm sheets for 0.5€ to 1.5€ each (depending width), not the more expensive styrene by Evergreen. When an attempt fails, I usually throw the sheet back in the oven and start again. Once you have the machine, you can make all kinds of things. You can make a lot of aircraft wings, airframe, panels etc out of a sheet like that. You can make the master molds from basswood, epoxy, polyester etc and the parts you make depend on how accurate the master molds are. The molds must be as accurate and detailed as necessary to achieve the results you are after. As you see in the following pictures, I tried white and clear styrene sheets too, in order to build the cabin by white styrene and the bubble canopy by clear.

I placed the frame into the preheated electric oven and I wait few critical seconds watching the plastic start heating. As soon as I noticed that it started drooping down, I removed the frame while wearing Nomex Aramid flame resistant MilSpec gloves, to prevent finger burns. While the vacuum cleaner was already switched on, I placed the wooden frame with the pined plastic sheet on the vacuum former plate. The plastic nicely formed around the “virtual” airframe mould... and voila!

Using my X-acto knife, I removed the formed cabin pieces from the styrene white or clear sheets and tried some test fitting on the cast.

To do so, some quantities of liquid modeling putty, filled between the gaping surfaces. In order to make the putty liquid and let it spread naturally and fill the tiny gaps, I mixed Humbrol putty with laquer thinner. Because the laquer thinner is volatile, the liquid putty mixture took about 45 minutes to get fully dry and be safe to sand - carefully ofcourse. If you follow this method, be sure that you mix the laquer thinner and the modeling putty into a metal or glass plate / canister, because the most plastic materials cannot stand it and melt. For this reason, keep in mind to use just the essential laquer thinner quantity, in order to remain the mixture in liquid form, as it is presented at the following pictures.

The last liquid putty layer was applied using the MMD green putty instead of the general purspose Humbrol, because I personally find it better for final smooth details.

Οραιος! Και μετα απο 25 χρονιἀ μοντελισμὀ ἐχω πολλἀ να μἀθω που το βλἐπω! Χἀρηκα που βρἰσκουνε κι᾽αλους Ελλινες εδω!

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The MMD green putty, also used to create some minor details on the cabin’s back side, where the tail boom frame (tail boom construction will be explained later) joints will be later fitted. At last, I tried many test fit attempts with the tail boob, to ensure that I’ll not face any unpleasant surprises later.

An additional green putty layer applied and the cockpit surfaces carefully sanded to look as smooth as possible, before sprayed with Mr. Surfacer 1200 as a final touch.

The instrument panel is made of standard Milliput epoxy putty, which is popular among modelers and also useful in countless household & restoration applications. Switch board, tail rotor control pedals, cyclic control stick and collective lever are made of drilled & cut styrene plastic card. Wiring is made of 0.20mm diameter fishing line.

Using styrene plastic card, I cut the basic lines to form into the student pilot’s seat. The dimensions and the shape are based on actual BO-102 pictures. Standard Milliput epoxy putty was used to simulate the pillow. Finally, the cabin sprayed with Humbrol light grey acrylic primer to show up any possible scratches that I did not spot so far..

Please keep in mind, that despite the fact that only 18 BO-102s were produced, the available pictures show that there were many and obvious differences between them in several places. Different seats (some of them were not even seat), different cockpit and cabin colour, different fuel tank canisters, different tail boom frame construction, different landing pad and some of the BO-102s, were not even equipped with landing skids. So, don’t be surprised if you witness differences.

Glanced through your thread and find it very well done.

Due to the scale & subject I would dare to say this will be the best, if not the only model of this scale & subject in the world.

Obviously you have the skills & time to do top work. The only thing that may hinder a submission for publication is the completely odd & rare subject. Worth a try though as your explanations are easy to read and follow for anyone wanting to try the techniques themselves.

Thanks for taking the time & effort to post here, I am sure others will agree.

Jason

* Sorry to hear about the problems in your country, I hope you & family are doing alright.

Jason,

Thanks for the comments. I am just an ordinary scale modeler and I am sure there are much better and more skillful scale modelers than me in this forum. Feel free to click the following thumbnails to have a look into some of my previous finished projects.

As for the problems in Greece, I suppose you are referring to the current economic crisis. Right? Well, let me say that IMHO the crisis is not just a "Greek" problem - its a European problem and EU should try to overcome as a unit or the Euro coin might collapse.. When there are countries such as Ireland, Spain, Greece, Portugal, Italy, Belgium already broke or about to broke in the near future, that means that Europe faces a serious problem and its not just a local bad luck or greedy finance of individual people.

As soon as the joints between the tail boom parts were securely glued with combination of CA glue and Humbrol liquid poly and later filled with MMD green putty on tiny gaps, it was carefully sanded with sand paper and nail files, found at the local supermarket and bought for less than 1 euro per 10 files.

The following toll attached to my miniplex to reach difficult spots and areas, that sand paper and nail files could not safely operate.

It was about time to sit back and take a break! I asked “honey” to prepare a nice cold Nescafe Frappé coffee for me. I had time for a close inspection on the model so far, while she was preparing this refreshment for me. For all you who do no clearly understand what is the Nescafe Frappé coffee, please let me explain that it is a foam-covered iced coffee drink made from spray-dried instant coffee. It is very popular in Greece especially during summer, but has now spread on to other countries. In French, when describing a drink, the word frappé means shaken and / or chilled; however, in popular Greek culture, the word “frappe” is predominantly taken to refer to the shaking associated with the preparation of a café frappé. For more infos, click HERE or visit a Greek island during this summer and relax on the beach enjoying a frappe coffee to feel the Greek way difference.

You might think that I throw away the plastic straw after drinking the coffee? Hell no! Just wash with water and I had the basic material to build the exhaust tube, right on scale.

The tail rotor blade was build by styrene & sprue, airbrushed and dry fitted into place to give me an idea if it looks right.

At last the battery pack was built of epoxy and some cables and flexible air intake hoses added too. Control cables and wiring made of 0.20mm fishing line. Tail boom fins are made of forded copper and styrene. The fuel tank canisters and the fuel lines will later described. Everything covered with a light grey acrylic and placed into box to wait the final painting.

This is one of best scratchbild i see here and good tutorial too!! also show how the cheaper way can be great

the subject is really strange , never see some like this

... only thing.. this is the aircraft section  

Looks to me like the model with the castors  is designed to perhaps roll around while hovering so that if the trainee gets to crossed, the large rubber bump stops on the blue frame hit the ground and act like brakes? So my guess then would be that the goal of the operator be to keep the bump stops from hitting the ground while trying to maintaining a hover? 

Or it could be that it's  museum and the curators need to move things around quite often so they put those castors on for just that purpose?

Oh and you make me homesick for Ellada seeing that Frappe! Although I usually drink Freddo when Im out for cafe in Glyfada...I think too much NesCafe is bad for you :)

bsyamato

This is one of best scratchbild i see here and good tutorial too!! also show how the cheaper way can be great. the subject is really strange , never see some like this

bsyamato

... only thing.. this is the aircraft section

JWalker

Looks to me like the model with the castors  is designed to perhaps roll around while hovering so that if the trainee gets to crossed, the large rubber bump stops on the blue frame hit the ground and act like brakes? So my guess then would be that the goal of the operator be to keep the bump stops from hitting the ground while trying to maintaining a hover? Or it could be that it's  museum and the curators need to move things around quite often so they put those castors on for just that purpose?

For my 1/18 scale project, I chose to recreate the wheeled version, which seemed to me as more interesting than others. As you can see in the following pictures, the landing pad & supporting base was built by styrene plastic, sprue, metal wire and glued with CA glue and Humbrol liquid poly.

jt-9t also great piece! 

keep on posting, lots of great ideas from you

When it looked OK to me, it was sprayed over with Humbrol acrylic primer to spot any mistakes and be ready for final paint. Each part was fit tested to ensure that anything can be combined together as one piece.

The twin epoxy blocks got trimmed and sanded gradually to shape into the desired form and look realistic Helitrainer fuel tanks into scale. Later, few thin layers of liquid scale modelling filler applied over the epoxy to smooth out small imperfections and be seen as a comprehensive outcome.

Nick, once again you combine great craftsmanship with good ideas and important safety advice.

(your relationship advice is also important to those who need it )

Enjoyed your JT-9T autogyro and this is as good.

**********************************

Oh and don't forget to oil (virgin olive in your case) the bearings in the tail rotor assy. - you DID make individual bearings and bearing races didn't you?

I think you are referring to the section shown in the following picture. Right?

Well, simply buy a cheap analog hand-winding alarm watch (the cheaper, the better) smash it with a hammer or if you're patient enough, carefully unscrew the casing. You will be amazed with the quantity of items you can use as spare parts. The part you are interested into, found into my spare box and as far as I remember is one of the unidentified little shiny things came out of an old & cheaper than dirt analog hand-winding alarm watch casing.

Each fuel tank, is placed on metal plate / receiver base and secured in place by hoops and tensioners, as seen into the following picture.

In order to reproduce, these metal plate / receiver bases, I tried vacuum forming. Because I was planning to use smaller wooden frame to secure the styrene (the pieces to be vacuum formed are small and there is no need to spend big styrene sheet), I had to close the outer holes on the hardboard high-density fibreboard plate. To do so, I cut a plastic bag in shape and covered as required the desired area.

The twin fuel tanks, wedged halfway into plasticine and placed on the vacuum former plate to form the fuel tanks receivers.

I pinned a styrene plastic sheet on the wooden frame, insert it into the preheated electric oven as described before and as soon as I noticed that the plastic got warm enough and started drooping down, I removed it from the oven and thrown the sheet on the vacuum former plate, while the vacuum cleaner was already plugged & switched on. This procedure may take some practice and sometimes a mould tips over or the plastic won’t form properly over the mould (folding around edges). This is also the part where I should warn you that you can burn your fingers - I highly recommend Nomex Aramid flame resistant MilSpec gloves, which I personally use for the job. I buy large plastic styrene 50x30cm sheets for 0.5€ to 1.5€ each (depending width), not the more expensive styrene by Evergreen. When an attempt fails, I usually throw the sheet back in the oven and start again. Once you have the machine, you can make all kinds of things. You can make a lot of aircraft wings, airframe, panels etc out of a sheet like that. You can make the master moulds from balsa wood, epoxy, polyester etc and the parts you make depend on how accurate the master moulds are. The moulds must be as accurate and detailed as necessary to achieve the results you are after.

The plastic nicely formed around the fuel tanks moulds and here is how it looks like.

Using a new Nr 11 stainless steel surgical blade, I removed the formed pieces from the styrene sheet. The yellow stuff appears in the picture, is plasticine surplus - the plasticine used to secure the twin epoxy tanks on the vacumm former plate and caged into vacuum formed plastic sheet. Later, these two receiver bases will be sanded as required and some details such as securing hoops and tensioners to keep the twin fuel tanks in place will be added.

It’s mid July already! It’s time to enjoy a nice cool summer and recharge batteries while drinking icy mojitos by the beach. I’ll meet all of you right after my summer holidays on sunny Cyprus island and I promise all the latest WIP pictures & updates when I’ll be back. I wish you best summer and happy holidays.

Nick

Great how-to for  vacuum forming

Glad you have a summer time off.

the last picture is Amazing! looks cool and inviteing- can almost hear the water lapping on the shore.

Looking forward to seeing  your work  when you return in the...

It’s been a long time since the last update, isn’t it? Well, I will not try to justify myself with cheap excuses. I’ve been so lazy the past few weeks and neglected the Bölkow Bö-102 Helitrainer project. Otherwise, I could possibly put the blame on anything but me, put the blame on the Mediterranean sun makes the summer last longer, put the blame on the planets spinning around the universe causing horoscope zodiac turbulences, put the blame on the Willie Coyote for keep failing to catch the Roadrunner, etc.

That would sound like a cheap excuse, wouldn’t it?

Some additional details were added to the fuel tank canisters. The left side fuel tank, was placed on the receiver base and strapped with hoops & tensioners to keep in place, while the right side fuel tank is to be placed on the ground, with the filler cap opened, simulating maintenance procedure. Finally, the landing pad base supports, built using balsa wood slats.

well done

Usually, there are two available options for a scale modeler, to apply paint on a model:

• Paint the individual parts first and assemble the scale model later and
• Assemble the scale model parts first and paint the overall built model later.

While building this Bölkow Bö-102 Helitrainer scale model project, the first option seemed as more appropriate and would make my job easy. Unfortunately, I had to follow the second option – and that was not the only bad news. Building first and painting later, would be more difficult and would take much longer, but the reason I chose first to assemble most of parts and paint later, is because most of the Bölkow Bö-102 Helitrainer scale model’s airframe consists of a tail boom structure, in which contained the Hirth 3-cylinder / 2-stroke 40hp ILO L3X375 piston engine, the transmission components, the cable wiring etc that could not be masked without causing any damage. It could be very difficult – maybe impossible - to airbrush for example the tail boom and manage to leave the interior details remain unaffected by the painting same time. Here comes the bad news: Tail boom structure would be painted by using fine brush and lot of patience to avoid leaving any brushing marks that would be clearly visible on such a big scale as the 1/18 is.

After preparing the engine’s basic elements, connecting electric cables and oil or fuel lines, I airbrushed the engine block with Life Color LC24 Matt Aluminium FS37178 acrylic paint as a base coat and apply darker enamel mixtures using the Humbrol #27001, #27002, #27003 metal cote paint and finally add some Mr Metal Color #212 Iron on the engine and let about 24hrs to dry before trying dark brown and black washes.

As I personally believe that following simple techniques and sometimes unconventional methods, result in superior effects, I usually do not use enamel or acrylic paint to wash, because I feel risky when applying the paint mixture and let it run. I prefer an easier technique that can be undone if the results are poor - that makes it the perfect technique. I use hard chalk pastels to wash (NOT oil pastels). The hard chalk pastels, looks like a teacher would use on the blackboard in school. Do not use the soft oil pastels that artist use to draw on paper. The hard chalk pastels are easy to find in a variety of colours into your local art store or maybe Wal-Mart if in US or ASDA if in UK.

To do the wash, I use an blade, a small metal or plastic container, an old toothbrush, dish washing soap and a bit of water. Begin by scraping some chalk powder from the side of the chalk pastel stick, carefully put this chalk powder into the small container and add a tiny amount of water and stir. It is important to add a tiny amount of water in order to make the mixture look like mud - not like soup! For this reason, I use a syringe to add just few drops on the hard chalk pastel powder and I stir using the old brush. Because the chalk powder doesn't mix well with the water, a drop of dish washing soap is needed to break the surface tension of the water and also acts as a “glue” to help the chalk powder stick to the model.

Once the chalk is fully dissolved into the water/soap mixture it is time to “paint” this mixture onto the model's engine. “Painting” the mixture is simple - just apply it anywhere it is needed to darken recessed detail. The mixture can be applied carelessly, because any mistakes can be completely removed and redone. Once the chalk wash dried, I rubbed off the high spots with a slightly damp dry (not wet) Q-Tip cotton swab (Kleenex papers can be also used) and I wiped the dark colour from the areas should be light & shinny. The high spots were cleaned to the bare metal finish and the low spots were left black. I did the chalk wash on the engine in under 30 minutes which makes it a very quick and effective technique. You can also read about this into Steve Bamford's article, by clicking HERE.

Some of the wash mixture is re-applied and the wash being wiped completely out of the narrow points. If you follow this method, it is adviced to not rinse out the wash container till you are finished this job. You will probably be touching up certain spots a few times, so it helps if you're not mixing up a new chalk mixture each time because you kept cleaning out your container of the chalk wash mixture. As soon as I paint the electric cables, the oil or fuel lines etc, I repeated the wash process with lighter colours where needed. Using micro cotton batons found into cosmetic shop for less than 1£, I applied some brown chalk pastel powder on the engine's chrome exhaust, to make it look overheated. I repeated the weathering process until it satisfied me and finally I sprayed a Humbrol clear coat to seal the chalk powder on the engine.