Hi there, my first question

[Guest]

Hi Bulo

[Guest]

Hi Bulo

Ive put a Photo of a Pilatus PC-21 in the planes gallery for you. It was taken at RAF Fairford at the 2002 IAT. hope you like it

Pogo

[wonwinglo]

Pilatus PC-21 as a scale subject.



Well lets take a look at this design Bulent and see its potential for scale modelling ? firstly the long nose looks good for electric or rubber power,heavy motors would need to be avoided due to the centre of gravity which could creep too far forward,tailplane is where it should be ie in line with the thrust line giving excellent fore and aft trim,moment arm is fine and would give fine response even with small control inputs,tall fin but not too much to cause weathercocking effect,bi-symetrical wing section would need changing for model use,except a fast IC design,shortish wings would give fast flights even with electric power,washout essential,suggest small inset ailerons,probably best to leave undercarriage off for small handlaunched model,if you do want the gear then build the nose leg to spring rearwards anchoring well into a hardwood block well anchored,watch the weight on this one.

On the debit side you have a large blown canopy, which would weaken the structure if consideration is not given to doublers in that area,a suitable plug would need to be carved from balsa and moulded as per the tutorial instructions.

Summing up,an attractive aeroplane that would need to be built of medium size to get a decent wing area,go for it.

[Guest]

Thanks wonwinglo,

The size of the wing ( with respect to the fuselage) is what that gets me worried; it will not be a slow flyer, as you said. The wings could be enlarged, deviating from scale, but this might need modification of the tail, etc..

Not an easy decision.. maybe in the future when I need a fast model.

[wonwinglo]

Bulent,I think the wingspan would be fine providing that the model was built large enough,I once built a Tucano that flew like a dream,it was only about twenty inches wingspan.Tailplane area would need enlarging,forgot to mention that.

[Guest]

Thanks wonwinglo,

and thanks Pogo, for the photo. I have found good photos on the web, also..

Bulent

[wonwinglo]

Mylar film supplies.

***Bulent,do you have a good source of supply for the Mylar film please ?

Bulent wrote-

'Thanks, but I will try thin mylar film (RA microlyte) covering instead of paper/paint, that should save'

[Guest]

Or Doculam ? It is only available in clear.

[Guest]

The light film I mentioned is produced in Canada. It is a low volume production - if things did not change - so a bit expensive. It is 5 micrometers thick and has color and heat sensitive adhesive on it. Homefly sells some colors :

http://www.homefly.com/products.asp?id=31

I have found the original company web site - I guess they do not sell directly..

http://www.ramicrolite.com/

Sorry duncan, I never have heard of Doculam..

[wonwinglo]

Covering models with Mylar type films.

Thanks Bulent,here are their covering instructions which help explain what type of material this is-

1. Apply a coat of dope first to the balsa where you want the mylar to stick. Paint all the way around the LE and TE to give plenty of gluing area. Let the dope dry for a few minutes.

2. Then rub a permanent glue stick along the perimeter of the flying surface. Elmer's, Avery Permanent, and Uhu are reliable brands. You can moisten the glue stick if it's too dry to give even coverage. Glue stick may also be applied with a damp artist brush, especially for confined areas or delicate structure. Use glue stick full strength on carbon rod structures (diluted glue stick doesn't have enough holding power to wrap around small radii).

3. Lay the mylar on top of the surface while at the same time pulling it taut. After it's on, keep pulling on the excess wherever you have wrinkles. You can usually adjust it a little if you lay it on lightly at first. Then burnish down and make sure it wraps all around the circumference of LE and TE in order to maximize gluing area. For flat structures, mylar may be taped to the building board (or held in place with magnets) and the structure laid on top. Let dry overnight.

4. For heat shrinking, use a very hot MonoKote iron or a heat gun. Do not touch the carbon rod with a hot iron.

Which type to use where

• For small balsa airplanes, 2um or 3um mylar is usually the best choice.
  
• For carbon rod flying surfaces or in those cases where more durability is desired, 4um or 5um is used.
  
• When using aluminized mylar, 2um usually shrinks more tightly and is easier to apply to compound curves than the 4um.
  
• 4um is recommended for use around window openings, windshield reveal molding or other detail applications, especially where it will not be heat shrunk. Small pieces such as trim strips are easier to handle if fabricated from 4um.

Painting

Clear mylar can be brush painted with ordinary model enamel, such as Testors, or equivalent. Tamiya enamel is recommended for transparent colors. Make a cartoon of the color scheme first and lay it under the mylar.

1. Areas on the cartoon to be painted white should be shaded; otherwise it will be hard to see where you’ve painted.
   
2. You need to be able to move the work surface to which the cartoon and mylar are taped. That way, you can turn the workpiece to a convenient angle as you paint.

Aluminized mylar is generally painted in situ after application is complete. Apply rivets and panel separation lines prior to painting. For lettering or color separations that are not straight lines, make a paper stencil first. Trying to use tape or adhesive to hold the stencil in place is not recommended -- the mylar is too flimsy for that.

Use a Sanford® Sharpie™ ULTRA FINE permanent marker to draw color separation border lines. Sharpies are available in the following colors: black, red, blue, green, orange, violet, brown, yellow, berry, turquoise, lime & aqua.

1. Hold the stencil in correct position and outline the area to be painted with a Sharpie pen that most closely matches the trim color. For straight lines, use a piece of scrap balsa or other flexible straight edge to guide the pen. Use dope thinner (acetone) to correct mistakes.

2. After the areas to be painted have been outlined, fill them in with enamel using a No. 2 sable artist brush (ModelMaster, Grumbacher or Floquil). Thin the paint if necessary to make sure it flows out. Begin at the pen line and work in, using plenty of overlapping brush strokes to ensure even coverage.

3. Then use a 3/8" flat artist brush for large areas. The enamel is slightly translucent so it’s important to apply the paint evenly (takes practice).

4. Corrosive and chemically reactive particles in dust can etch the aluminum and create clear spots. To prevent this problem, make a storage box for airplanes that are covered with aluminized mylar, or cover metal side in.

[Guest]

Doculam is the very thin material used for laminating photographic enlargements. slightly milky in appearance until heat shrunk whereupon it goes crystal clear,gloss or matt, can be painted, strong, has heat adhesive already on. Disadvantage: only available in commercial sized roll, 100mtr for £17, so try scrounging smaller amount from local pro photolab. The UK supplier is www.muro.co.uk Look for "laminating solutions" there, gives thicknesses etc. Might be a Greek agent.

[Guest]

oh i remember that stuff, when my mate was into r/c everything!!! (fixed & rotary wing, buggys, touring cars...etc) its brilliant and magic stuff!!

speaking of him actually, would anyone be interested in an i/c car or helicopter? he still has them but has no interest any more!

i can get all the details and specs if anyone is interested

[wonwinglo]

Yes our local photo lab down at Asda have a big roll on the workbench,often wondered what this material was ? they must heat shrink it over the pictures,sounds ideal for a lightweight covering.

[Guest]

Hi wonwinglo,

I beleive the mylar covering instructions you included above cover all types of mylar; glue stick may be necessary for some types only. As much as I know ra microlite does not need external glue. I did not use the stuff yet; but Dave Robelen says so, and he should know..

Thanks duncan,

Any information on what thicknesses are available for doculam? There are lots of Kodak shops here, so it may be available by begging or by other means

Material being sold in large quantities makes me remember the availability of Depron sheet here. It can be bought in 40 square meters minimum and only in 3 mm thickness so I can not use it

[Guest]

Bulo, according to the above site it comes in 35, 75, 125 and 250 microns thickness. A full description can be found on www.muro.co.uk/laminate/laminating Then go to the box "laminating consumables" look for "roll laminating film". The thinnest is good for up to 24" wings (and tailplanes of same span). Too bad about the Depron, bulk purchase by a group or club(s) perhaps?