1/18 scale Tervamaki Engineering JT-9T autogyro Step-by-step scratchbuild
#21
Postat 05 October 2009 - 03:47 AM
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The Tervamaki Engineering JT-9T autogyro designed by Finnish engineer Mr. Jukka Tervamaki, is equipped with a twin "H" shaped tail. To build this, I started by rolling flexible styrene sheet around a plastic tube and forming as required to look like the real JT-9T autogyro right side elevator main wing - only 18 times smaller. Following, using the sandwich method (placing one plastic sheet over another), cutting carefully and working extensively with sandpaper to form into desired size and aerodynamic shape, I manage to build the right side stabilizer wing. As you understand, the left side elevator wing, the stabilizer and rudder, will be stripped in a way to show the airframe aluminum skeleton.
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#23
Postat 15 October 2009 - 03:34 AM
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.
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Yeah, yeah, yeah... I know! I am a button stealer, but let's admit it! We all prefer less buttons on female dresses.
#25
Postat 15 October 2009 - 09:37 PM
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.
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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.
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.
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Aceasta postare a fost editata de Nick_Karatzides: 15 October 2009 - 09:51 PM
#26
Postat 28 October 2009 - 05:12 PM
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In brief words, the color layers popped and "cracked" everywhere on the model's 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 "pilot's error" - OK, I made a rookie's 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.
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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 Eddie's Live After Death, I decided to try a full reset – after all, I had nothing to lose! The scale model was already FUBAR.
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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!
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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 I've 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.
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Following the product's 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!
- - Hey man! I need something really strong to clean up kitchen's oven?
- Really strong? Use this!
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- - Are you sure that this will work? Are you sure that this is safe to use?
- Trust me. It's gonna clean up the kitchen's oven like a nuclear bomb!
- How much?
- 3.50 € . Take it or leave it.
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Aceasta postare a fost editata de Nick_Karatzides: 28 October 2009 - 05:17 PM
#28
Postat 28 October 2009 - 08:21 PM
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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 bottle’s 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.
#30
Postat 29 October 2009 - 10:27 AM
Very impressive work ! Congrats !
I'am watching very closely
Happy modeling,
Bill
P.S. After finishing you must send the autogyro "Somewhere in time" to find the "Seventh son of a seventh son" and return with the "Flight 666". But take care this is a "Matter of life and death"
Eddie rules !!
#31
Postat 29 October 2009 - 11:41 AM
Some guy's are using brake fluid, this is also corosiv, so it's gone work the same way and "eat" the paint.
Regards,
Tibi
#32
Postat 29 October 2009 - 03:56 PM
tibi22, la 29 Oct 2009, 12:41, a spus:
tibi22, la 29 Oct 2009, 12:41, a spus:
- It is cheap with only 3.50 € per litre,
- It is plastic friendly and does not damage or effect modeling putty inserts,
- It is easy to use, because you only need to simk the model into a bowl filled with NaOH and wait 20 to 40 minutes until it is copletely color free without even try brushing.
Bill, la 29 Oct 2009, 11:27, a spus:
Aceasta postare a fost editata de Nick_Karatzides: 29 October 2009 - 04:07 PM
#34
Postat 29 October 2009 - 11:29 PM
Nick_Karatzides, la 29 Oct 2009, 15:56, a spus:
You`re never alone my friend! Another fellow from "Transylvania" tells you not to have"Fear Of The Dark" and to "Be Quick Or Be Dead" , we want to see this model "Live at Donnington".
Honestly, this is a one-of-a-kind work.
#37
Postat 14 December 2009 - 11:53 PM
#40
Postat 18 January 2010 - 02:25 AM
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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:
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The masking tape that I had used, had left noticeable marks on the transparent part of the canopy - something that had never done before! Beeing 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.
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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.
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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.