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General control line discussion => Open Forum => Topic started by: Steve Dwyer on February 22, 2021, 11:19:28 AM


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Title: Scallops painting not eating
Post by: Steve Dwyer on February 22, 2021, 11:19:28 AM
This might be more suited for the Painting and Finishing Forum but I'll throw it out here first. I want to paint descending diameter scallops on the wing and stab of my Jameson Special since I thought this would be a fitting design for a 50s style model. I need to make two templates.

I'm sure one of you smart guys know of an easy formula for determining the sizes for each scallop given the length of the area, the largest and smallest size scallops and the approximate quantity within the space. This of course is simple if the scallops are identical in size but changing dimension baffles me. Seems like a like compound interest question sort if in reverse?? I've never been strong at deriving functions only applying them, and sure I know by now I could have laid it out using a circle template in the time I've spent writing but hey I'm curious.

This is probably easier than I thought but then my mind doesn't function like it used to.

Thanks

Steve



Title: Re: Scallops painting not eating
Post by: Howard Rush on February 22, 2021, 03:36:51 PM
I fiddled with this in CAD.  The first set starts with a 1.5" radius.  Each successive semicircle has .1" less radius.  I don't like the result, but it might be OK for a curved LE.  I think the curve tangent to the semicircles might be a parabola.  I did the middle set by multiplying each semicircle's radius by .75 x the radius of the semicircle to its left.  It looks like that makes all the semicircles tangent to a line.  The bottom set is the same thing, but with a ratio of .86.  The rate at which scallop size peters out seems to be sensitive to this ratio.  You can probably figure out the formula you're looking for from this, assuming this is the look you want. 

If you like either of these methods, you can do them with a compass, or I can send you a CAD file from which you can get  masks made.
Title: Re: Scallops painting not eating
Post by: Warren Walker on February 22, 2021, 05:58:56 PM
Steve, the easiest way I found was buying different masking tape dots from McMaster-Carr, they have them from 1/8" to 4" dia.
All you do is lay them out in whatever graduations you want and them connect them with 1/16" tape. Be sure you put them on a tee
shirt or some kind of clean material first they are very sticky.

W.W.   
Title: Re: Scallops painting not eating
Post by: Avaiojet on February 22, 2021, 06:33:33 PM
I did this in minutes.

Should be self-explanatory, you can see the scallop line.

Sure, I make these all the time in graphics and masks. I've never made scallops using a full half circle. I don't think I've ever seen a vintage aircraft with full half circles.

All these models have vinyl graphics or masks by CFC Graphics.
Title: Re: Scallops painting not eating
Post by: Howard Rush on February 22, 2021, 10:26:14 PM
Here’s the formula, I think, for semicircle scallops with a straight line tangent to all the semicircles, as in the middle and bottom sketches on the picture in my post above. 
D = the sum over n scallops of 2R1*k(i-1) , where D is total distance, R1 is the radius of the first (biggest) scallop, k is the ratio of the radius of a scallop to the radius of the bigger one next to it, and i is scallop number, starting with the biggest one. 

Given R1 = 2.25” and D = 23.5”, 7 scallops will give you a radius of about 1.2” for the last one; 6 scallops will give you a radius of about 1.69” for the last one.
Title: Re: Scallops painting not eating
Post by: Steve Dwyer on February 23, 2021, 11:02:27 AM
Thanks guys,

Howard has been gracious enough to send me the equation in excel so I can play around a develop the configuration that looks best.

Charles, I have to say the full half circles do appear a bit much compared to say a one quarter. I'll look at this configuration as well.

Thanks,

Steve

Title: Re: Scallops painting not eating
Post by: wwwarbird on February 23, 2021, 07:51:18 PM
 Instead of the headache of fiddling with one mask and trying to get it right just use individual circles and overlap them as needed to create your desired look. If you need varying diameters so be it. I've gone to the local vinyl shops before and had them cut me a sheet of circles out of vinyl masking material, just tell them what size(s) you need and how many. Get some extra ones too. Doing it this way makes the job MUCH easier and you can precisely align things as you go.
Title: Re: Scallops painting not eating
Post by: wwwarbird on February 23, 2021, 07:54:48 PM

 More of the finished product...
Title: Re: Scallops painting not eating
Post by: Skip Chernoff on February 26, 2021, 03:14:33 PM
Nice looking plane!
Title: Re: Scallops painting not eating
Post by: Robert Zambelli on February 26, 2021, 03:30:26 PM
More of the finished product...

WWW - THAT is clever and beautiful!!!

Bob Z.
Title: Re: Scallops painting not eating
Post by: Steve Dwyer on February 27, 2021, 04:39:41 AM
YES IT IS FOR SURE! It gives me new ideas for my unfinished VECO Chief as well. Just more scallops along with my unfinished Jameson Special.

Steve

Title: Re: Scallops painting not eating
Post by: Avaiojet on February 27, 2021, 12:05:29 PM
YES IT IS FOR SURE! It gives me new ideas for my unfinished VECO Chief as well. Just more scallops along with my unfinished Jameson Special.

Steve

This is a VECO Chief.

Title: Re: Scallops painting not eating
Post by: Trostle on February 27, 2021, 01:03:55 PM

This is a VECO Chief.


Charles,

I am confused.  Are you calling that tapered wing thing a Chief.  A Veco Chief has a straight wing with tapered flaps.

Please explain.

Keith




Title: Re: Scallops painting not eating
Post by: Avaiojet on February 27, 2021, 02:26:37 PM
Charles,

I am confused.  Are you calling that tapered wing thing a Chief.  A Veco Chief has a straight wing with tapered flaps.

Please explain.

Keith

Yes, I know that.

Take a good look, you don't see a VECO Chief hidden in that thing?

I was given a built Chief wing and a built Chief fuselage but nothing was assembled. I also think, not sure, I believe the tail feathers were included.

I wanted something, a model, which I could consider a challenge, so I built the Tank Buster around the Chief parts.

I've always had interest in the Stuka so I got creative. I believe, someplace in the Build, I have photos of the ongoing model laying on the VECO plans?

I'd go look but I'm busy removing grout, which I really don't enjoy doing.

Your reply gave me the brake I deserve, Thank you.

Removing grout is no picnic.

CB
Title: Re: Scallops painting not eating
Post by: dennis lipsett on February 27, 2021, 05:03:53 PM
I have done a few scallops over the years. This is a Satellite Saucer by Pat King
and is larger than the original 14 inch size of the original Jetco model.
I use Frisket paper  and draw and cut out the template. put it in place and cover the surrounding area. It is not fully stunt worthy but it does fly well and is fun for a change of pace
Title: Re: Scallops painting not eating
Post by: john e. holliday on February 27, 2021, 08:42:55 PM
The saucer looks great.  Should get a lot of attention even though it would never win the Nationals stunt event. H^^
Title: Re: Scallops painting not eating
Post by: Steve Dwyer on February 28, 2021, 07:18:24 AM
Joe Wagner Chief without the pollywog airfoil. Distinctly a Chief wing and fuse configuration.

Steve
Title: Re: Scallops painting not eating
Post by: Avaiojet on February 28, 2021, 09:37:07 AM
Joe Wagner Chief without the pollywog airfoil. Distinctly a Chief wing and fuse configuration.

Steve

Smart.