1/18 scale Tervamaki Engineering JT-9T autogyro

Nick_Karatzides · August 10, 2009, 11:58pm

1/18 scale Jukka Tervamäki Engineering JT-9T autogyro scratchbuild

Having tried my (suicidal) virgin 40 minutes flight experience with a friend’s homemade autogyro during my summer holidays with him on flight controls and me on the passenger’s backseat, I can surely say that you really feel like a bird, sensing even the slightest airwave or gravity accelerating change straight in your floating stomach. As soon as I safely stepped on solid ground again and returned back home in one piece, I felt the iresistable temptation to try a 1/18 scale autogyro scratchbuild. The following article is to describe step by step the 1/18 scale Jukka Tervamäki Engineering JT-9T autogyro, designed by Mr. Jukka Tervamäki and currently flying by ultralight aviators around the world keeping the Mad Max II GyroCaptain’s (aka Road Warrior) spirit alive!

In the photo below, Mr. Jukka Tervamäki, with his latest (at that time) creation of the JT-5, which was a predecessor of JT-9, which I’ll try to represent in scale.

The basic JT-9 autogyro concept is about a tractor gyro design with good aesthetics and performance with fairly low power. A 1.7 m diameter 2-blades propeller is powered by HKS 700 or Hexadyne Aviation P60 diesel engines, both delivering about of 65 hp at 2400 rpm. The fuselage of the JT-9 is of normal steel tube construction covered with dacron fabric. On the other hand, the JT-9B model is equipped with an electric motor instead of a diesel engine, with only difference the 3-blades propeller and wider front cover to house the battery packs onto both sides of the fuselage. The model I’ll try to build in 1/18 scale, is the two-seat trainer (as for the “T”) JT-9T model, equiped with diesel engine & 2-blades propeller made by carbon fibers. Having the basic blueprint line diagrams in hand, it was easy to convert them into 1/18 scale with a photocopier and I began the scale model building, starting from zero using 0.25mm styrene card and plastic sprue. To make the construction look more interesting, I decide to build the model in a way that airframe should look like cutaway side opened and let cockpit detail be easily observed.

In the following pictures, the real (one-seat) Alex’s autogyro JT-9, during the successive stages of building.

Nick_Karatzides · August 11, 2009, 12:02am

CHAPTER I - Basic airframe skeleton construction

Following the 1/18 scale printed diagrams and using just a sharp blade and ZAP superglue, it took about 60 minutes to build the basic airframe skeleton. The tiny gaps between the skeleton connections, were filled with Humbrol modeling putty, applied with an old brush. In order to make the putty liquid and let it spread naturally and fill the tiny gaps, I mixed it 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.

About 45 minutes after laquer thinner and Humbrol putty liquid mixture applied with brush on the skeleton to fill the tiny gaps between the connections, it looked to be fully dry and safe to sand it. As soon as that was done, the skeleton was hanged by a string and airbrushed with enamel mat white color as a base coat. Cockpit floor, wheels etc made while waiting the putty to dry, were also spayed with base coat.

Nick_Karatzides · August 11, 2009, 12:10am

CHAPTER II - Diesel engine building & painting

Setting as a task to build the model in a way that airframe look like cutaway side opened with cockpit and engine bay details visible, I should also leave the engine’s cover opened. that offcourse means that a diesel engine building from scratch is something I couldn’t easily avoid. Using plastic card, sprue, metal wire and unidentified parts found in the sparebox, here is my effort to build a realistic 1/18 scale engine.

After connecting with superglue the main elements, the electric cables and oil or diesel lines etc on engine’s shape, I airbrushed it with enamel mat white color as a base coat, using high air pressure and spraying from distance to develop a pore surface and help silver & aluminum paint establish easier on plastic or metal engine’s parts. As soon as the enamel mat white color seemed dry enough, a mixture of silver and aluminum paint sprayed on the engine and let about 24hrs to dry before trying to wash it with darker colors.

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, look 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 X-acto knife, a small metal or plastic container, an old brush, 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 color from the areas should be light & shinny. The high spots were cleaned to the SNJ 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 diesel lines etc, I repeated the the wash process with lighter colors where needed. Using micro cotton batons found into cosmetic shop for less than 1£, I applied some red, orange, purple & brown chalk pastel powder on the engine’s chrome excaust, to make it look overheated. I repeated the weathering process until it satisfied me and finally I sprayed a clear coat to seal the chalk powder on the engine.

The scale model building, cost me almost nothing and took about 2 evenings work so far. I also send some pictures of my secret hideout / hobby room while scratchbuilding the 1/18 scale JT-9T autogyro model. Click on the first image to enlarge hi-res 180 degrees panoramic picture.

Daywalker · August 11, 2009, 12:18am

Nick,

This really is incredible stuff to watch. Your use of unconventional techniques, different mediums, and such are incredible! I am learning much from watching you work. Thank you for the detailed explanations and incredible photography. [bow]

Teonguyen · August 11, 2009, 1:57am

Thank Nick for posting this …i alway wonder how many types of wash do modelers really have? what i know so far is sludge wash or enamel.By reading your post, i like the idea of using chalk pastel to do weathering for engines or machines…May i have you a question? Are these pastels you used can be easily purchased at any supply stores?? I saw HobbyLobby also has a set of inexpensive chalk pastel. Would that one work…Thanks

Nick_Karatzides · August 11, 2009, 2:21am

I used to follow the enamel wash method for years and I’ve ruined some very good paints by applying accidentally thinned enamel color into spots where it shouldn’t be, resulting nusty spots. You might say that thinned enamel color could be removed by wiping with a slightly damp dry with white spirit Q-Tip cotton swab, but in most situations, the white spirit resolvent also swap the camouflage paint. With this method, the chalk can always be cleaned completely off the model with warm water and a soft toothbrush, anytime! You can apply it carelessly, because any mistakes can be completely removed and redone. So, as long as the result is not accepted, as long as the panel lines on your aircraft model do not look realistic to you, it is absolutely safe to removeit and try again.

As I wrote, you can find these hard chalk pastels in a variety of colors, into your local art store or else. Don’t expect them to cost more than 0.50 - 0.75£ each. Possibly, these chalk pastels you found into HobbyLobby, are just right for the job. Be sure that they are NOT the oil soft pastels used by artists to draw on paper. The hard chalk pastels sticks, look like the white chalk sticks a teacher would use on the blackboard in school. Here is a picture of the Faber Castell sticks, found in EU market.

You can also use these chalk pastels, to simulate weathering, color fading, smoke effects etc by applying carefully the chalk powder on the desired surface, with cotton batons, hard or soft brushes, or other stuff depending what you have in mind.

Borg_R3-MC0 · August 11, 2009, 2:50am

WOW, you are of to a good start for your scratchbuild![wow]

666Irish · August 11, 2009, 6:16am

Incredible! That engine is mind blowing!

The heat staining on the exhaust is simply stellar, and really sets that engine off. It actually looks like it is still glowing.

I, for one, am humbled by your work here.

Pawel · August 12, 2009, 4:56am

Hello Nick!

Nice job, I really like it! How about the F-16, did You get tired? I hope not, have a nice day

Pawel

Nick_Karatzides · August 12, 2009, 5:06am

Maaaaaan, gime some time. I’ve just returned from summer holidays and have no updates. The 1/18 scale F-16CJ Fighting Falcon Block 52 HAF scratchbuild project will go normally as planed and I’ll send some updates as soon as I have some.

…for the time being, my mind is still away

Nick_Karatzides · August 30, 2009, 9:10pm

CHAPTER III – Instrument panel & cockpit construction

The original Tervamaki Engineering JT-9T autogyro instrument panel is not what you would call as “glass cockpit”. Actually it does only have just the basic instruments in cockpit to provide the pilot with information about the flight situation, such as height, speed and attitude. Since the JT-8T autogyro is not designed to fly in conditions of poor visibility or night, the main information is available from visual reference outside the aircraft. Of course, many pilots who are lucky enough to own an autogyro, they might add more sophisticated equipment such as CFT screens, HSI - Horizontal Situation Indicator to follow VOR signals, GPS screens, VHF/UHF radio, replace the heading indicator by a GPS-driven computer with wind and glide data etc. The basic instrument panel is consist by:

I started by cutting the main panel shape in plastic and drilled the gauges positions. Using the Corel Photo Paint, I created a colored sketch of the instruments, copy & paste the image into a MS Word new file and print it on a simple A4 page. Meanwhile, I add some detail on the instrument panel, such as rivets made by streached sprue inserted in drilled out holes, knobs etc.

RadMax8 · August 30, 2009, 9:41pm

Nick, your informational posts are absolutely amazing! All the information is so cool!

Could I ask you something? Why 1/18th scale? It just seems a very strange scale to people like me, used to 1/48th, 1/72nd, ect.

Keep up the good work. Love the exhuast pipe on the engine!

Nick_Karatzides · August 31, 2009, 5:33am

Just like any aircraft scale modeler, I started with 1/72nd scale, tried the 1/48th, liked the 1/32nd, stayed for a while on 1/24th, but after building on 120mm and 1/15th scale Verlinden’s products and finaly fell in love with the 1/18th scale F-16CJ Block 52 HAF, I realised that I have a real problem. My shrink says that I suffer from “Californian girl syndrome” and my GF told me that I keep saying “big is beautifull - big is beautiful” in my sleep.

…who knows?

Luftwoller · August 31, 2009, 3:58pm

Nick, fantastic project and its going well by the looks of things. The detail in your photos is stunning. I didnt realise a cutting mat looked like that p so close LOL.

Also great news that the F-16 is still going.

…Guy

Nick_Karatzides · September 4, 2009, 8:44pm

Using styrene plastic card, I cut the basic lines to form into the two simple seats. The dimensions are based on the basic 1/18 scale JT-9T two-seat trainer blueprint line diagram as seen HERE. On the real JT-9T autogyro, these simple seats are made of hard plastic, fiberglass or even wood sheet and buckram covered home made pillows are placed to provide comfort. These seats are fixed on metal rails, running across the cockpit floor connected with main skeleton, to ensure seat’s secure installation.

For many years, I was used to form aircraft seat pillows with Milliput epoxy putty, which is popular among modelers and also useful in countless household & restoration applications. But, while I was in a supermarket last week, I found the following item and I thought that it could be nice to try it and start experiment with this material. It’s an air-drying modeling clay ideal for scale modeling and shaping. According to the instructions, it can be easily formed into shape, become solid rock withing few hours, re-filled or sanded if neccessary and painted or lacquered. That sound quite good to me and similar to the well known Milliput epoxy putty, with the only difference that the 500g air-drying modeling clay pack cost only 1£, instead of 100g Milliput epoxy putty which cost 5£. That makes the new found air-drying modeling clay, about 25 times cheaper than Milliput epoxy putty and that’s a good reason for me to give it a chance.

Picking a small quantity with a metal spatula and applying the air-drying modeling clay on the seats, it felt too soft and very easy to spread the material nicely to simulate pillows realistic way. I didn’t want to care too much and try forming and shaping the clay, because I was planning to cover the sculpted pillows with wet soft paper to simulate the buckram covered pillows. After all, I had no idea how much available time I had, before the material start becoming hard and difficult to handle.

Luftwoller · September 5, 2009, 5:05am

Great stuff Nick. It looks like a that clay has nailed it. Are you going to (Did you) texture the clay to give the impressions of cushions?

…Guy

Nick_Karatzides · September 15, 2009, 10:47pm

Toilet paper is not only for the obvious purpose but can also be useful for scale modeling. I used ordinary toilet paper, cut it to shape and dress the seat pillows made by air-drying modeling clay, to look more realistic and simulate the buckram covers. 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 formed the paper on the pillows with a wet brush, into the desired shape. Because the mixture is enriched with water based glue, the soft toilet paper becomes hard when the water dries.

MIflyer · September 16, 2009, 9:02am

My jaw is on the floor. [:O]

This is really great work! Thanks for going to the trouble to share it in detail with us.

Kevin

Nick_Karatzides · September 23, 2009, 11:00am

CHAPTER IV - Right side fuselage construction

As I said at the beginning of this thread, I decide to make the JT-9T building look more interesting and show the model in a way that airframe should look like cutaway side opened and let cockpit detail be easily observed. THIS artistic diagram gave me the idea and that would be a nice opportunity to present my way to do it. To do so, I decide that a solid rock one-piece “negative image” cast of the right side fuselage should be made of plaster first and then build a right side solid replica made of polyester, epoxy or resin. This replica - virtual fuselage, would be the basic line to create a thin right-to-scale fuselage surface.

My local newsagent, usually wraps my newspaper and magazines into a plastic bag, which sometimes I use to collect the trash. This time, I decide to use the plastic bag in a completely different way. I cut free-hand few pieces of plastic, keeping in mind to make them longer & wider than the autogyro scale model dimensions. Using duct tape, I stretched the plastic bag across the airframe, in a way to simulate the full right side and half bottom fuselage surface, trying not to leave any visual wrinkles or marks.

Nick_Karatzides · September 23, 2009, 11:04am

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 plastic bag was dry and hard enough, a second thin layer of plaster was applied to form a basic strong cast. The basic idea, is to let the plaster follow the airframe details, accurate on scale and as thin as possible trying not to apply extra stuff where is no needed.