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Old Sep 27, 2009, 02:38 PM
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Beech 18

I decided that I was going to start on my first scrachbuilt foam aircraft and the Beech 18 sounded like a good place to start. I was interested in building the Balsa model that is being sold but the estimated constuction time was 50 70 hours which seemed like a lot.

I found some views with sections and sized it for a 48 inch wingspan. The windshield was the hardest part. The other sections are hotwiring out nicely.
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Old Sep 28, 2009, 09:01 PM
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I was using a hotwire that I got from a hobby shop that only has about a 5 inch wire which was not wide onough for one of the sections so I made a bigger one out of 3/4 inch PVC, a metal sinker from Walmart and a battery charger. It works very well. I am a little surprised how much foam hotwiring consumes.
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Old Sep 29, 2009, 08:46 PM
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I have been printing out the templates on cardstock which I then attach to the foam with 3M spray adhesive. It works very well in the printer adn can easily be cut out with scissors. Unfortunately if the hotwire stops for s split second it burns into the cardstock and gets stuck which ruined one section and damaged another. I seem to recall someone suggesting coating the edges of the template with CA so I may try that next time.
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Old Sep 30, 2009, 05:31 PM
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Hello gcook12,

The Beechcraft Model 18 is a beautiful plane, it's great that somebody start to scratchbuild one !

Any photographs to share with us ?

Regards

D.C.
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Old Sep 30, 2009, 08:33 PM
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Quote:
Originally Posted by gcook12
I seem to recall someone suggesting coating the edges of the template with CA so I may try that next time.
Backin '93 I made quite a few gliders using a hotwire. I didn't have access to a band saw so I used shoe boxes to make my templates then I went around the edges with aluminum tape (like that used in heating and airconditioning), I was able to make many wings with the same templates.

Meldrac
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Old Sep 30, 2009, 09:10 PM
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Quote:
Originally Posted by Dreamcatcher
Hello gcook12,

The Beechcraft Model 18 is a beautiful plane, it's great that somebody start to scratchbuild one !

Any photographs to share with us ?

Regards

D.C.
I will make some photos to post soon. Right now I am kind of ashamed of it but filler can cover a lot of sins. I have the sections made to about where the last window is on the fuselage is. One discovery that really surprised me was that I had to use a planview template and a side view template to rough out the windshield section and the two views were of a slightly different scale so the sides necked down a little right behind the windshield. Light filler can work wonders but I am a little bit concerned about what that is going to do to the weight. Thanks for your interest. I should have a picture or two posted in a few days.
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Old Sep 30, 2009, 09:20 PM
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Quote:
Originally Posted by Meldrac
Backin '93 I made quite a few gliders using a hotwire. I didn't have access to a band saw so I used shoe boxes to make my templates then I went around the edges with aluminum tape (like that used in heating and airconditioning), I was able to make many wings with the same templates.

Meldrac
That sounds like a great idea. Thanks! I will give that a try. The only thing that concerns me about that technique is that it would seem that the tape would fold when you go around a curve. I guess that I can notch it to keep it from gathering. I tried putting a little CA on the edges of a test template and then touched it with the wire and it burns in after about 5 seconds deep enough to make a nick big enough to catch the wire which is not much longer than the regular card stock can stand.

I did some reading about templates and it seems that the weapon of choice is to bandsaw them out of formica or circuit board material and then sand and polish the edges and apply a final coat of graphite. Sounds like a lot of work and there has to be an easier way. I think one thing that I may be doing wrong is I am spraying them with 3m and applying it to the foam. I think the glue may be oozing out around the edges and slowing things down. Kind of fun figuring out what will work if it wasn't so much work to laminate the foam.
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Old Oct 17, 2009, 09:39 AM
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Attached are a few photos of progress to date. I had to stop because I have to earn a living. I am hotwiring out sections about 4 inches long and attaching them with CA.
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Old Oct 19, 2009, 08:55 PM
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I started making the bottom half and it has been going much better. I found some scrape formica and it is a lot easier to work with than I thought and unlike cardstock, it can be reused, something that will come in handy on those unplanned nose first landings.
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Old Oct 25, 2009, 09:09 AM
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Sparks Book?

gcook12,

Excellent build. I plan on building the Beech D-18 someday.

Have you seen/read sparks book on scratch building with foam?
It might help with some of your issues.
Take a look at this post.

Daniel

http://www.rcgroups.com/forums/showthread.php?t=571313

When you open these PDF's, Click 'VIEW' then scroll down to 'ROTATE VIEW' and rotate colckwise or counter clockwise for best viewing.
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Old Oct 25, 2009, 08:13 PM
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Quote:
Originally Posted by dlazarus6660
gcook12,

Excellent build. I plan on building the Beech D-18 someday.

Have you seen/read sparks book on scratch building with foam?
It might help with some of your issues.
Take a look at this post.

Daniel

http://www.rcgroups.com/forums/showthread.php?t=571313

When you open these PDF's, Click 'VIEW' then scroll down to 'ROTATE VIEW' and rotate colckwise or counter clockwise for best viewing.
Thanks for the tip. I did not know about his book but it looks like exactly what I need. I am making my wish list for Santa and will definitely put that on the list (3 stages of life: you believe in Santa, you don't believe in Santa, you are Santa). Thanks again, it looks like he has solutions for some of the problems that I am obviously going to run into.

That is interesting that you supplied the same plan views that I am using to make my templates. For some reason, my drafting program does not like to import PDF files bit it takes gifs and I found those same drawings on the internet in gif format. The only thing that seems to be missing is a good description of the airfoil.
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Old Oct 26, 2009, 04:59 AM
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Hi gcook12 !

Glad to see that you started to build your Beech 18 project

Quote:
Originally Posted by gcook12
The only thing that seems to be missing is a good description of the airfoil.
You know, except for your knowledge, some airfoil informations about the original beech 18 will not help you a lot in the design of a scale R/C model.
Your plane's wings will have to use far smaller Reynolds number, wing loading, weight and a lot of other specs than the "full size" Beech 18's wings.

If you want to be quiet, i think you can use some good olds airfoils like NACA 2415 or a "Clark Y" clone (might be easier to build because of the flat bottom). Generaly the "olds" profiles are more tolerant in case of shape's imperfections than the recent ones.

Bye
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Last edited by Dreamcatcher; Oct 26, 2009 at 05:05 AM.
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Old Oct 31, 2009, 09:08 AM
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Attached are a couple of photos of progress to date. The bottom of the fuselage has gone together much better since I started using formica templates. The current weight is 2 oz.

In the background is a Tomhe f-16 that I am building to have something to fly while I build the 18. The F-16 goes together quickly and flys very nice.
http://www.rcgroups.com/forums/showthread.php?t=867416
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Old Nov 01, 2009, 07:34 AM
If it flies, I crash it!
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Take another look.

gcook12,

Take another look a plate 3 of 3(the middle PDF)
It shows the NACA airfoil at the root, engine nacelle and the tip. It gives the dimentions in feet and inches also. It should be easy to trace out the wing.

I hope this helps.

Daniel
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Old Nov 04, 2009, 10:38 AM
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Originally Posted by dlazarus6660 View Post
gcook12,

Take another look a plate 3 of 3(the middle PDF)
It shows the NACA airfoil at the root, engine nacelle and the tip. It gives the dimentions in feet and inches also. It should be easy to trace out the wing.

I hope this helps.

Daniel
I don't know how I missed that thanks!! That shows very well how it is attached to the fuselage.
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