1/18 scale Tervamaki Engineering JT-9T autogyro

Nick_Karatzides · Skill Level 3

1/18 scale Tervamaki Engineering JT-9T autogyro

Nick_Karatzides · Skill Level 3

CHAPTER VI - Landing gear system construction

The single seat JT-9 and the tandem seating JT-9T, are available with tricycle landing gear system with a steerable nose wheel or a taildragger version too. For both types, the type of landing gear is based on the placement of the exact CG position, determined after complete weight calculations according the owner/pilot's personal needs. My 1/18 scale model is designed to be equiped with a tricycle landing gear system with a steerable nose wheel. An utillity free-spinning tail wheel is also placed, to prevent any accidental damage on tail structure if the autogyro raise nose too high while in ground. Feel free to check the diagrams and images found into my first post of this project, back in page 1.

Using plastic card, sprue, metal wire, resin tires and brakes fit accurately to 1/18 scale diagrams and few unidentified parts found in the sparebox, I build a realistic looking 1/18 scale main landing gear system with absorbers and a steerable nose gear. I stole a nickel plated button from GF's favorite dress (hope she'll never find out where's the missing button or I'm in real trouble), placed it into a plastic tube piece, covered with with transparent plastic card & add some details to simulate the landing light in scale.

Yeah, yeah, yeah... I know! I am a button stealer, but let's admit it! We all prefer less buttons on female dresses biggrin

Nick_Karatzides · Skill Level 3

CHAPTER VII - Canopy construction

The Tervamaki Engineering JT-9T autogyro canopy is made by bented and cold-formed 3mm polycarbonate sheet. The backwards sliding canopy of the single seat JT-9 version, offers the possibility to taxi and fly slowly with the canopy open, a benefit in a hot climate. The trainer / tandem seating JT-9T, has a side opening one piece canopy. Of course, canopy modifications can be done, according the autogyro owner's personal needs or desires.

I used styrene plastic card to form it as shown into following pictures to give the basic shape of the canopy. Then, a layer of polyester filler applied on the styrene. The specific polyester filler I used, comes with the proper catalyst which provides a solid rock build and approximately 3 to 5 minutes time window to form it into shape. I prefer to use epoxy putty or polyester filler with fiberglass grains for special purposes, because:

It becomes solid rock within only few minutes or seconds,
it does not shrink and does not crack after months or years,
you can pour to any shape that you want but you need to work fast because as soon as you mix it with catalyst cream approx 5%, you have limited time before becoming solid rock,
you can also put additional layers of epoxy or polyester filler to build up,
you can sand it, you can drill it, you can use any type of scale modeling glue, any type of primer or enamel / acrylic paint on it with no problem,
can be purchased at any good crafts store into 250ml, 500ml, 1lt (comes with a tube of catalyst hardener) or bigger canisters and if you can't find it, fear not and try your local decent hardware store and finally...
it is cheaper than dirt - estimated prices are £3 to £10 depending the canister size, the quality, if contains fiberglass grains for maximum strenght etc.

Keep in mind that the chemical reaction after mixing the polyester filler with the catalyst hardener, produces some heat that possibly effect on thin plastic parts, so test it first before try it on your scale model. I dont think that the produced heat is more than Fahrenheit 110, but better watchout. Remember that epoxy materials are dangerous when breath or shallow and could result skin, eyes or lungs problems or even cancer when used for long period with no precaution measures. Always keep in mind, that a powerful vacuum system to suck away the epoxy dust should be used all time to keep the workbench area clean while sanding or milling epoxy or resin materials. Using an issued breathing mask and a pair of surgery latex gloves to prevent dust contact with lungs and fingers while sanding or milling epoxy, is also an important matter that you should seriously take care of! My recommendation is to also wear an overall working suit (as I do) to keep your clothes dust free while sanding epoxy. Some people might find it too much, but I wouldn't like to bring epoxy dust & grains from my work bench into living room and my beloved.

When the basic canopy shape made by styrene sheet, was fully covered by a a thin layer of polyester filler and had enough time to polymerize and get solid rock, I sand it with wet sandpaper to make the cast curved and shiny. To produce a thin-skinned canopy, the polyester part should be vacuum formed. As described into previous chapters, a transparent plastic sheet were pined on a wooden frame, preheated into electric oven and as soon as I noticed that it started drooping down, I vacuum formed it. The clear plastic nicely formed around the canopy cast following the curves & details as planed. Using an X-acto, I removed the formed canopy buble from the transparent sheet and start adding details, such as canopy's frame. Few drops of cyanoacrylate glue applied on the right spots with great caution. Remember that CA glue does fog the transparent parts and this canopy would not be an exception - that's why I placed some very tiny drops of it, just on few spots.

Nick_Karatzides · Skill Level 3

Its sad! Obviously, voodoo curses came from the unspeakable dirty Viper snake, got real and the final varnish finishes on the model suffered what the Americans call as FUBAR - F@cked Up Beyond All Recognition.

In brief words, the color layers popped and cracked everywhere on the models surface, just before the final touch. For some mysterious reason, the color looked peeled off and an unexpected chipping (I would never succeed this by purpose) appeared! The scale modeling accidents committee is expected to investigate the possible reasons within following days, but unconfirmed sources report "pilots error" - OK, I made a rookies mistake, while using old colors or coat varnish.

Meanwhile, the following actions took place:

Garlic cloves were hanged across the workbench to keep away evil curses, vampires and snakes (or those who claim themselves as snakes),
The scale model were covered with a thick layer of ModelStrip product, locked tightly in a plastic bag and left overnight to let the chemical work.

CHAPTER VIII - Live After Death

When I started building the model, I did not expect to present the CHAPTER VIII under this title. Bus as all the sad & bad situations in life, it was unexpected and accompanied by great frustration because suddenly I saw months effort to dissolve in only few minutes. The old colours (or bad white spirit solvent) that I used, have led to drying crack. Unfortunately, I ignored all the warning signs such as thick grains left by the white colour in which I primed the scale model before the final painting. Having as target to make this model alive again, just like Iron Maiden Eddies Live After Death, I decided to try a full reset after all, I had nothing to lose! The scale model was already FUBAR.

The following photos show the unsuccessful paint process. The problems appeared marked inside the red circles. Unfortunately, I have no photos of the model while looked completely written-off, because at that time I was not in a mood to take pictures!

ModelStrip, was the first thing came up as the most conventional solution to try paint removing. Following the instructions on the box, a generous stuff applied on the model, wrap it with airtight plastic bag to prevent drying and wait about 15 hours to let the chemical work. Opening the bag next day and checking the results, the colour (or rather the colour layers) were soft and could be removed by rubbing vigorously with an old toothbrush. Unfortunately, using the brush on some very delicate spots (even with careful use), had as result to break / or ruin a couple of plastic pieces. Moreover, the paint could not be removed through narrow points and difficult locations.

At this point and while Ive already used all the ModelStrip material without being satisfied with the outcome, I decide to change tactics to something more unconventional, such as oven cleaner.

Following the products directions as always, I sprayed the model with the material, wrap it with airtight plastic bag to prevent drying and wait about 15 hours to let the chemical work. Testing results next day, the oven cleaner failed no more than ModelStrip. I noticed that the colour could be removed but only when pressure and persistent rubbing with brush and that was prohibitive for some parts of the model. Not having another solution, I approached the most unconventional method and visit a science specialist - my local grocery store!
and he gives me a dust covered 1lt plastic bottle found in an almost unreachable shelf. Reading the bottles label, I found out that it contains sodium hydroxide also known as lye (corrosive alkaline substance) or caustic soda and is a caustic metallic base. It is used in many industries, mostly as a strong chemical base with chemical type NaOH.

Thinking about a possible failure, I filled a plastic bowl with the milky liquid contained in the bottle and threw all the model pieces inside. As long as the autogyro model was already FUBAR, I had nothing to loose to try. I sealed the bowl with a cover and leave the sodium hydroxide to act for 20-30 minutes while the instructions sets out to wipe the sodium hydroxide chemical liquid after 10 minutes. Opening the plastic bowls cover, a nice surprise followed...

The truth is I was delighted! Styrene pieces simply and magically totally striped off the enamel colour layers! Absolutely success, without even apply brush cleaning! Amazing product - incredible grocer! Just because I couldnt believe it and I wanted to make sure that the colour striped off because of the sodium hydroxide chemical (and not the previous used ModelStrip product or the kitchen oven cleaner), I decide to experiment. I threw in a bowl, already filled with the chemical, a 1/18 scale female figure that I was about to convert for a future project. The specific 1/18 scale female figure, is made by Fast Women brand and can be found by clicking HERE). The results after just 15 minutes in the sodium hydroxide chemical - Perfect! The following pictures, show the "before" and the "after".

Keep in mind that the sodium hydroxide is (and thus should be considered) a strong caustic base. This means that:

Throughout the impregnation of the model parts into sodium hydroxide, you should take all the necessary protective measures (like mentioned in the warnings on the bottles label) and is certainly to use disposable surgical gloves made by latex and breathing mask with appropriate filters to protect against possible fumes.
The colour stripped plastic parts must be rinsed with soft acid to neutralize the caustic base and produce salt and water. Dunking the colour striped parts in plastic container filled with cooking vinegar and then rinsing with plenty of lukewarm water, plastic is now safe to handle with bare hands.

-- Edited by Nick_Karatzides on Monday 29th of March 2010 02:12:43 PM

Nick_Karatzides · Skill Level 3

Under the above "adventure" circumstances and considering that all these years dealing with the scale modeling I've tried many color striping methods (including ModelStrip, kitchen oven cleaners, blue alcohol, brake fluid, nitro laquer disolvent, etc), I think that sodium hydroxide NaOH is the best method so far, for the following reasons:

Kitchen oven cleaners in spray canisters, can do the job, but they cost 3 - 4 for a 300ml product in which also includes the propellant gas. On the other hand, the NaOH in liquid form is a pure substance, much less price, taking for 1lt bottle, which equals 3.3+ times more product! Using the liquid form NaOH (which you can fill a plastic bowl), you can sink several plastic pieces, same time!
The brake fluid may be effective and remove paint, but it is not plastic friendly plastic and is likely to convert the scale model into a blob of molten plastic. It is clearly more expensive and as far it is highly toxic, flammable and hardly to manege, I will not recommended it for scale modeling use.
Nitric acid laquer disolvent, could be a nice solution for metal figures paint striping, but it is not the best for the plastic. Just like the brake fluid, it does melt and damage plastic parts.

-- Edited by Nick_Karatzides on Monday 29th of March 2010 02:14:06 PM

Nick_Karatzides · Skill Level 3

CHAPTER IX - Applying paint, wash & weather effects

Model parts were washed with liquid soap and warm water to disappear leaving oil traces, fingertips etc and then sprayed with light grey primer.

The first base color layer sprayed with no problem and then a second white color layer applied on specific spots to simulate enlightened areas. Then, using very diluted acrylic color Vallejo paint, 2-3 extra thin layers were sprayed throughout, until the result become realistic and simulate correctly the enlightened areas.

As soon as the previous layers of acrylic Vallejo paint and gloss coat varnish dried, I placed small slips of paper between the frame and the sheet of the fuselage, to protect the red colour that was already applied and dried. Next, I masked areas not to be painted using the adhesive Tamiya tape and sprayed with the interior green colour.

-- Edited by Nick_Karatzides on Monday 29th of March 2010 02:15:35 PM

-- Edited by Nick_Karatzides on Monday 29th of March 2010 02:22:11 PM

Nick_Karatzides · Skill Level 3

After the interior colour dried, the slips of paper and adhesive masking tape removed and minor corrections were made in 1-2 spots with a fine brush. The result was sprayed with gloss varnish, to apply washing on certain points.

-- Edited by Nick_Karatzides on Monday 29th of March 2010 02:17:21 PM

Nick_Karatzides · Skill Level 3

The steps are slow, but I prefer steady progress rather than hastily. Unfortunately, the problems are not missed. Although I do not think myself as awkward, after the incident with the (voluntarily flying) autogyro model scaffolding under my sleeve and threw (launched to be precise) on its own initiative, brought about 4 or 5 spin turns and finally abnormal landed about 5 feet away and 3 feet lower, I begin to believe that this model has been seriously voodoo curses. Despite the delicate structure of the fuselage, the use of CA glue and maybe a mirracle, were the main reasons that the model escaped having suffered only a broken landing gear, scratchbuilt again.

After the scale model was masked & sprayed with primary colors as described above, the same methodology followed for the canopy, scratchbuilt by transparent plastic on a vacuum former. After the acrylic paint and mat enamel coat dried, I removed the masking tape and I saw the following:

The masking tape that I had used, had left noticeable marks on the transparent part of the canopy - something that had never done before! Being sure now that this scale model is indeed cursed, I dropped by the local grocery store around the corner from where I returned with few garlic cloves. Not having a similar experience before and fearing that if I try to clean the masking tape glue marks using White Spirit will make the things worse with a huge dull hood, I tried to rub the clear plastic part with alcohol which although more friendly to transparent plastics, had to pass crash test first. Dipping a cotton swab in alcohol and water solution and vigorously rubbing the hood, the masking tape glue marks, finally removed as if it was gum.

With my heart beating on normal levels again and using airbrush, light tones of basic colours and shades of sand sprayed at low pressure to represent the weathering and dusting on LG and the lower part of airframe. After a satisfactory weathering result, the scale model was sprayed with mat enamel coat. I left it 24 hours to dry and the individual parts of the scale model were test assembled (no glue), so that the autogyro model start to look like a united construction and please the eye.

Having now left the last part of the assembly of the individual already dyed parts of the model, such as the rotor blades, the cockpit flight & engine controls, the cables, the seat belts and other necessary details, I begin to hope that perhaps this model might be ready in 2010.

-- Edited by Nick_Karatzides on Monday 29th of March 2010 02:19:06 PM

Nick_Karatzides · Skill Level 3

Some update pictures after washing / weathering / colour fading. Control cables are already installed. Still remain to be added:

The canopy,
Both propellers,
The radio device & GPS,
The engine control levers,
The windshield and windscreen wiper,

and also paint some details such as engine cables etc.

Details on rotor blades and the engine. The rotor blades are made of
sterene sheet softened in boiling water to strech 'n' turn in a way to
look realistic. Soft sanding applyied on the blade's leading eadge to
be shaped as it should be. The spinner cone was made of an old 1/48
scale fuel tank tip, found in sparebox.

The JT-9T model posing for the camera...

-- Edited by Nick_Karatzides on Monday 29th of March 2010 02:20:29 PM

Nick_Karatzides · Skill Level 3

CHAPTER X - Epilogue

Final details were added. VHF radio with headphones in the cockpit, mobile phone, seat belt buckles, main rotor control bars, cables, etc. To break the monotony of red, a toolbox and a tow added into rear storage area. At last, transparent plastic card were placed to simulate the wind shield glasses and of course the canopy in the open position.

Close-ups of scratchbuild engine. Although initially I plan to represent a brand new bright and shiny engine I discovered that it would not fit the with a faded, dusty and weathered autogyro. That is why I preferred to add much wear, stains from oil and scorched medals at several points and some rust as example in the exhaust.

The controls in this two-seater model autogyro, as with any trainer aircraft, perform the same movements. Feel free to notice the rudder pedals and you will see that the front and the back seat, right pedal is pressed to full FOR, bringing the left full AFT. This has resulted in turning the nose wheel to the right and turning the rudder of the tail in such a way as to twist the autogyro to right as defined by the position of the rudder pedals. Also notice that the throttle lever of back seat is attached on a bar connecting to the front seat engine throttle so to move simultaneously. The engine's power transmission is made with a wire, launched by the front seat throttle lever and lead the assembly of the engine. Finally, the control sticks are fallen slightly forward, which of course means that the elevators are set in a similar position.

Nick_Karatzides · Skill Level 3

Ive been asked about the available space where the rear passenger puts his feet on. From the pictures of the model have been published, and the art images (click HERE) found on the articles first page, it appears that the rear seat is too close to the back of the front seat - and it is also clear from the bluebrints (click HERE) of the real autogyro that its not my own assumption or a model building mistake. In real autogyro, rear passenger's feet are not squeezed behind the front passenger seat back, but they are placed left & right of the front seat! To make it more understandable, here is a picture where:

The green lines represent the front seat passenger and the position of his feet on the rudder pedals and
The blue lines represent the rear seat passenger and the position of his feet on the rudder pedals.

Also notice that the position of controls (stick, rudder pedals and engine throttle) meet the relative position of the elevator and rudder fins, the nose wheel, etc. The front & rear seat rudder pedals perform exactly the same movements as linked to the same wire transmission. If you also check the rudder pedals position, youll notice right rudder pedals pressed front end, bringing the left rudder pedals full back. As an effect, the nose wheel turns to the right and rudder fin turns in a way to turn the autogyro to the right as defined by the position of the rudder pedals. In similar manner, both control sticks (which perform exactly the same movements as they are connected to the same bar drive) are positioned slightly forward. This has the effect of elevator fins rotation so as to oblige the autogyro in the descent, as defined by the position of the control sticks. In a similar position the main rotor head is placed as required. As it is known, the autogyros and the helicopters leans to the left or right, elevates nose up or descent nose down, by turning the main rotor blades disc and secondarily to aileron and elevator fins (if present) and turn to left or to right with the rudder fins (autogyros) or tail rotor (helicopters).

Click HERE to watch a video showing a tandem cockpit seating positions as described. Picture following too.

Nick_Karatzides · Skill Level 3

CHAPTER XI - Display base & grass

Its been few months since the JT-9T project was complete. I found nice idea to place it on a display base, simulating an airfield area with concrete ground. The idea was to establish an idea of an abandoned small airfield, now used by general aviation pilots for their weekend excursions. From my local store, I bought a 20x30cm polished wooden picture frame.

I add some grams of plaster powder and few drops of water with a syringe into a soft rubber cup to make the right mixture. Materials like plaster, start as a dry powder that is mixed with water to form a paste which liberates heat and then hardens. Unlike mortar and cement, plaster remains quite soft after drying and this characteristic make plaster suitable for the job. Keep in mind that adding salt into wet plaster mixture, reduce the plaster's hardening time and adding vinegar into wet plaster mixture, extend the plaster's hardening time. When the first layer of thinned plaster applied on the picture frame, a glass were pushed against the plaster to form a flat basic strong cast. The basic idea, is to produce a totally flat cast and later add some detail or apply extra stuff where is needed.

I left it few hours to get harden in order to be sure that the cast wouldn't break when I would try to cut it into desired shape. Meanwhile, I took the soft rubber cup which I used to make the plaster mixture, squized it to break the last hardened plaster left inside, so it would be easier for me to clean it afterwards and prepare it for any future mix. That's the reason this soft rubber cup were used for.

As soon as the plaster cast got harden, cut into shape and the concrete plaques were lined with a scriber, I used my airbrush to paint it. After the polished wooden frame was covered with masking tape, three different acrylic paint layers were applied on the plaster surface. First, mat black colour covered the area and then a light grey applied with airbrush, spraying in almost zero degree angle, to let the darker areas between the concrete plaques remain naturally dark. The corner was paint with earth tones and as soon as the acrylic colours dried, I tried some drybrushing on selected spots using sand tones.

As for he grass & plants, I used three different ways:

From my local hobby shop, I got different colours of static grass, empty them into a plastic box and make a mixture.

Found into my garden perimeter, I collect few natural stuff, cut and placed into plastic box for such use.

From my local super market, I got a small wicker broom. If you look closely, youll find some very interesting stuff for scale modeling use and dioramas building.

Water based white glue for wood, which becomes transparent when it dries, is just the right for the job. So, I opened a 500 grams canister bought for 2 only, pick a small quantity, add just few drops of water with a syringe into a small metal container to make the right mixture and finally I applied on the desired areas to be filled with grass & plants, using a wet brush. Because the mixture is enriched with water based glue, it is easy to correct possible mistakes.

As soon as the result was OK, I sprayed over with Humbrol enamel mat coat, to seal the paint and grass, so far. I left it overnight and as soon as the enamel mat coat dried, I add very few light & dust effects with chalk dust. Feel free to check final pictures of the JT-9T autogyro placed on the display base.

Thank you for following this thread and I hope you enjoyed reading this article.

-- Edited by Nick_Karatzides on Saturday 10th of July 2010 12:09:49 PM