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Mr. Tompkins in Miniscaleland - chapter 1: selecting the model

Mr. Tompkins

At first let’s explain how Ruja (me) appeared in the miniscalemodelland, in the land where spars are measured with slide caliper, hobby jackplane is good only as paperweight, paints are dissolved into homeopathic concentrations and surgeons tweezers become integral part of the hand. Pure luck brought me after ten years together with my university schoolmate, not knowing that we both are modellers. ISim (yes, that’s the guy) was returning to modeling world after 15 years break and he returned in the free-flight style – his first RC EPP kit model flew away on its third flight and was never found. So his desperation from bad control and searching for the RC model flying teacher caused that all went the other way around…

At Lesná, on the meadow behind soda works, I once watched ISim with his son flying Bobík (no, it’s not the dog). Limited space, tiny airplane, huge excitement of three years old son. As I’m the owner, holder father of little boy only slightly older, decision was made. Bobík, upper wing monoplane designed by Ing. Koutny will be my first miniplane. It is not a scale model, but if you never built a tiny aeroplane, it’s a good “workout”. I got the plan and a first bunch of advice from ISim. In nightmares I still hear his sentence “that should not take longer than two afternoons”. It did not take two afternoons, for example after the first attempt to assemble the stabilizer I took it out of the plan with shaking hand and was admiring my skills for about one second before the stabilizer disintegrated into individual spars. But the built went slowly ahead and it’s a good thing to try something similar, miniscales model novice gets at least the rough idea what can be expected. I’m no beginner, I went through classical school of free-flight models, CO2 models and ended with RC models, so I have some experiences. The free-flight model building reminded me of the “legendary fifteen” times (me and my friend Smoukt were trying to reach the 15 seconds limit with hand-launch glider, the only promising attempt was made by Víťa Kaderka and his model painted in silver, that ended up in the high voltage line wire where it burned with spectacular effects). Bobik does not have the parameters of competition airplane, but ISim taught it to fly one day on the field near Velké Opatovice and my decision to built a miniscales model was irreversible.

For start I abandoned the idea of my own design (in spite the fact that I like to build what I design and draw myself). If you have no experience with miniscale models I would recommend the same for you. There are plans to download from the Internet, some can be found in the book “Modely letadel s gumovým pohonem" by Lubomír Koutný (published by Computer Press) and one plan is already available on this server. When I get the plan, I always get a mug of coffee and look at the plan, think how to make certain parts and nodes and if it can not be designed in better way (usually no).

My first miniscale was BV 215 driven by low pressure Rapier rocket motor (plan is available on Mike Stuart's pages here) - the choice was clear – it is WEIRD airplane and those are my favorites. Plus on internet discussions it is noted to be a “good flyer” and that is good indicator, as it makes no sense to start with a wild plane too difficult even for old miniscale Master. I tried Minilot as my first peanut model (plan from Koutny’s book). However, the peanut has its name for a reason – dimensions shrink from unbelievably small to absurdly small, spars 1.5x1.5mm will now remind you of roof beam and ability not to breathe becomes essential for successful building (if you make that error during building and breathe out, the complex design you spent all afternoon working on will disintegrate and fly all over the living room; if you breathe in you will cough the remains of the plane for several days). Therefore you will definitely not make a mistake if 1/20 scale will be your first miniscale model – dimensions are larger, it survives a bit rougher approach than peanut and free space for flying is easier to find compared to the hall for peanut.

And one more advice, probably not agreed by my professors: when selecting a model, select original you like ! If it does not fly well, it at least looks great and you will have motivation to finish the model.

Final advice is a bit dry: if it is possible, discuss your choice with experienced modeler. Ideal would be a colleague from the same city and discussion over the glass (bottle) of beer, wine, tea, mead, … (strike out inapplicable). If such a friend is unavailable, someone in discussion forum will definitely help, I would recommend free flight section on mojehobby.cz (in Czech only) or group groups.google.com/group/minimaketycz (mainly in Czech). For English speaking modelers useful discussions can be found in SmallFlyingArts (rubber)and Jetex.org (rapier). The possibility to discuss problems with somebody is important mainly at the beginning, as sometimes it is not all clear from the plan how to do certain things. Plans from kits are usually advantageous, as the building instructions are detailed and accompanied with diagrams. The building itself can be done by yourself (however the colleague is a big help), trimming flights are more challenging, somebody experienced is definitely handy there. Luckily as the free flight events are reappearing lately, it is a good occasion at the end of competition to find the time for trim flights.

Today’s trip into miniscale land is over, in the next chapter we will move towards hobby shop and get some material.

And at the end of the chapter we have little quiz. Which model from following selection is more appropriate for the beginner?

McDonell XP-67 Bat, building and photo Felda Minilot, building and photo Ruja

A: McDonell XP-67 Bat

B: Minilot

And the correct answer is.................... A off course! What a beauty!

Professors notes...

ISim's notes:

As I accompanied Mr. Tompkins Ruja and probably directed his steps sometimes, this note will be short. As with all other issues it is good to soberly judge ones abilities and as a first miniscale model select the size and type which one is capable of finishing. Preferences are different and as ladies always pick a car according to its color, there are modelers-beginners who select airplanes according to obscure criteria. I know one guy who selected first model according to the number of cannons of the original.

Following table can help as a guide for model selection, directly by plan selection or as a guide for model size, shape and design. With just a little effort you can find more plans on the Internet or in older issues of model magazines, so you don’t have to limit yourself to the planes in the table.

If you take a look at more plans from different corners of the world, you will see that the plans differ significantly in both the design approach and level of detail. American plans are usually full of instructions, detailed axonometric drawing and each rib, keel and former is there. Wings have several thin spars on the surface, leading edge is made of the spar inserted into ribs, oval fuselages are octagonals with several deep seated stringers rather than oval. Plans from our part of the world are more “sober”, there is usually only root and end rib drawn on the plan, wings have spars hidden inside, leading edge is glued end-to-end and oval fuselages are designed as “polygonals” with many stringers not seated into formers. Each solution has its advantages and drawbacks and after a while everyone will find his favorite style.

Little advice: if you obtain a plan, it is not a bad idea to measure it and find the documentation to the original airplane. It is possible that person who had the plan before you got it used the copy machine and changed zoom ratio for some percentage. It is annoying to build a peanut with 350mm wingspan.

Type Category Complexity Note
Itoh 62 M-min (1/20) beginners Plan with building instructions was published in the book "Dvacetinky - plány a návody pro stavbu gumou poháněných maket letadel" (ISBN 80-252-8018-3), L.Koutný (in Czech)
Arsenal VG-39 M-min (1/20) advanced Plan with building instructions was published in the book "Modely letadel s gumovým pohonem" (ISBN 80-251-0042-1), L.Koutný (in Czech)
Nakajima Ki-84 "Frank" M-min (1/20) advanced Plan can be ordered from Model Hobby magazine web (http://www.model-hobby.cz)
ZLIN Z-226A "AKROBAT" M-min (1/20) intermediate Plan can be ordered from Model Hobby magazine web (http://www.model-hobby.cz)
Letov Š-39 M-min (1/20) intermediate Free plan is available on this server: minimakety.cz
Beechcraft Musketeer M-min (1/20) beginners Plan with building instructions was published in the book "Modely letadel s gumovým pohonem" (ISBN 80-251-0042-1), L.Koutný (in Czech)
HL-2 Peanut beginners Plan with building instructions was published in the book "Dvacetinky - plány a návody pro stavbu gumou poháněných maket letadel" (ISBN 80-252-8018-3), L.Koutný (in Czech)
Zlin Z-50M Peanut intermediate Plan with building instructions was published in the book "Modely letadel s gumovým pohonem" (ISBN 80-251-0042-1), L.Koutný (in Czech)
Saab J-29B Tunnan Rapier intermediate Plan can be downloaded from Mike Stuart’s web pages

Felda’s notes:

Everything important is already above, so just a few notes:

For start I would avoid unusual concepts such as flying wing, canard, multiengine and multi-plane airplanes, etc. Even if you can read on discussion forums how great those models fly, it does have its specifics in both building and flying. So my recommendation is – choose nice upper-wing monoplane with long nose. There are numerous airplanes of this type and many model plans available, anyone can find the plane of his heart. Such model forgives some imperfections in building and fumbling how decalage change influences the flying.

When we have the model chosen and building plan found and correctly zoomed and printed, there is time for “coffee over the plan”, as Ruja mentioned. I recommend to thoughtfully study the plan and create virtual 3D model of its construction in your head. One has to focus on design nodes where several parts of the model connect and think carefully how various spars and stringers and formers interconnect and how the intersection of those parts will look like. This way we make it clear what influence a modification of the design will have changing the stringer or former position for a single millimeter compared to the plan.