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Hot Topic (More than 10 Replies) Grumman Goose G21a Lost foam process (Read 5257 times)
LoCo
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Re: Grumman Goose G21a Lost foam process
Reply #13 - Sep 29th, 2021 at 8:46am
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Ok thanks!
  
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Sky9pilot
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Re: Grumman Goose G21a Lost foam process
Reply #12 - Sep 23rd, 2021 at 11:14am
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No plans available...I just did a quick plan from 3-views I found on the net blown up to the size I required.  Sorry!
  

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Re: Grumman Goose G21a Lost foam process
Reply #11 - Sep 23rd, 2021 at 10:58am
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Hello,
Awesome build. Are plans available for this Grumman Goose G21a?

Cheers,
Les
Vancouver Canada
  
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Re: Grumman Goose G21a Lost foam process
Reply #10 - Jul 12th, 2017 at 1:19pm
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Skye,
The lacquer thinner, as expected, dries pretty fast. It evaporates quickly so make sure you put the lid back on the tin to avoid losing your thinner!!!  I'm looking forward to doing another lost foam project in the near future.  For a bit stronger formers for the fuselage I'll laminate the balsa rings.  The reed does fine for smaller models with a max wingspan of say 16-18".  Over that the reed requires internal bracing.  Check out the Douglas F4D build I did a while back. Just looked and because of Photobucket you can't see anything!!! Tongue Cry  Guess I'll have to repost those pics too. 
Edit: 
Pictures reposted...looks ok but may be a bit out of order...
Tom
« Last Edit: Aug 1st, 2017 at 4:45pm by Sky9pilot »  

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Re: Grumman Goose G21a Lost foam process
Reply #9 - Jul 12th, 2017 at 12:00pm
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Wow!  I learned a lot about the foam process and using lacquer thinner to help dissolve the foam when the frame is completed.  Does the lacquer thinner have any affect on the balsa stringers?  Any signs of warpage?  How long for the drying process on the balsa before commencing with the build?  Great idea and great techniques.  Thank you very much for the build thread.  It's really apprecited.  Skye
  
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Re: Grumman Goose G21a Lost foam process
Reply #8 - Jul 12th, 2017 at 10:01am
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Bob... it's a lot like the old solid models that you carved out of a chunk of balsa.  Instead it's foam that sands a lot easier.  I went to the dollar store and bought a box of dryer anti-static sheets and periodically rubbed the foam down with the sheets and it kept the sanding foam dust from sticking on the sand paper, me and all the stuff around me.  Worked great.  If you're going to sand foam this is a neat trick to assist that process.

I got me a 4" diameter pvc pipe two feet long and an end cap...filled it with the lacquer thinner and dipped the fuselage in the pipe till the foam melted. 

The glue I used was Cyano (super glue)  This held up to the lacquer thinner very nicely. 

I just poured the lacquer back into the gallon tin through a cloth to filter out foam chuncks and particles.  It turned pink because of the pink foam.  But I was able to use it several times.  I lost the thinner in a move.  Not sure just what happened.  My movers didn't mention that they couldn't pack the liquids...they just allowed those large plastic storage containers to disappear.  I lost a lot of modeling supplies this way.  Had I known I'd have packed that in the car back seat.  Live and learn.
Tom
  

If God is your Co-pilot...switch seats...
Your attitude will determine your altitude!- John Maxwell
And ye shall know the truth, and the truth shall set you free. Jn 8:32
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Re: Grumman Goose G21a Lost foam process
Reply #7 - Jul 12th, 2017 at 8:10am
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I would like to see a video on this lost foam process. Great looking Grumman Tom. Smiley

Bob
  
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Re: Grumman Goose G21a Lost foam process
Reply #6 - Jul 12th, 2017 at 6:33am
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This melting foam process is simply great and can be expanded to other areas of the build as well since the lacquer thinner doesn't seem to bother the wood but need to ask what glue your are using as lacquer thinner will soften aliphatic resins (Titebond, etc.). I use the lacquer thinner process in my wood shop for creating multiple, identical small parts. I make a template, spot glue together the required number of parts in a stack, glue the template to the stack and cut and sand to shape, then pour lacquer thinner on the stack and soon have as many identical parts as I needed for the project since it dissolves the glue but leaves the wood alone. This should work for multiple wing ribs and other parts as well. The only draw back is the disposal of the used lacquer thinner as I need to take it to my local recycler.
  

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Re: Grumman Goose G21a Lost foam process
Reply #5 - Jul 12th, 2017 at 12:21am
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Still working out the electric Free Flight timer and power system...looked at several motors but settled on the Air Hogs capacitor systems less the capacitors.
Brushless motors but decided against them...some generic brushed motors but they were way too heavy.

Also looked at making my own Peterborough timer from plans posted on HPA...I need more soldering skills at present.
Tom
  

( 47 KB | 84 Downloads )
Peterboroughtimercomponents.jpg
( 72 KB | 81 Downloads )
AD5brushlessmotorrulerforsize.jpg
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motorsandruler.jpg
( 178 KB | 67 Downloads )
airhogsbox.jpg
( 145 KB | 89 Downloads )
4brushedmotors.jpg
( 98 KB | 80 Downloads )
Airhogmotorlesscapacitor.jpg

If God is your Co-pilot...switch seats...
Your attitude will determine your altitude!- John Maxwell
And ye shall know the truth, and the truth shall set you free. Jn 8:32
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Re: Grumman Goose G21a Lost foam process
Reply #4 - Jul 12th, 2017 at 12:06am
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Here's the black applied with acrylic craft paint thinned with water.
  

( 37 KB | 119 Downloads )
GoosePaintupperleftfrntqrtr.jpg
( 39 KB | 95 Downloads )
GoosePaintupperrear.jpg
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GoosePaintupperrightfrntqrtr.jpg
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Mrknslowerrightfrntqrtr.jpg
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Mrknsupperrearview.jpg
( 79 KB | 111 Downloads )
Goose20N78920d1.jpg

If God is your Co-pilot...switch seats...
Your attitude will determine your altitude!- John Maxwell
And ye shall know the truth, and the truth shall set you free. Jn 8:32
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Re: Grumman Goose G21a Lost foam process
Reply #3 - Jul 12th, 2017 at 12:02am
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Tissue applied on the orange and black Alaska Fish and Games scheme.
Tom
  

( 24 KB | 105 Downloads )
GooseOrngtissueleftrearqrtr.jpg
( 24 KB | 86 Downloads )
GooseOrngtissuelowerrightrearqrtr.jpg
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GooseOrngtissuenoseview.jpg
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GooseOrngtissuelowerrightsideview.jpg
( 35 KB | 84 Downloads )
GooseOrngtissueupppernoseview.jpg
( 41 KB | 84 Downloads )
GooseOrngtissueuppperrightsideview.jpg

If God is your Co-pilot...switch seats...
Your attitude will determine your altitude!- John Maxwell
And ye shall know the truth, and the truth shall set you free. Jn 8:32
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Re: Grumman Goose G21a Lost foam process
Reply #2 - Jul 11th, 2017 at 11:58pm
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More bones mockups...
  

( 81 KB | 81 Downloads )
closeupnacellesleftside2.jpg
( 44 KB | 71 Downloads )
floatsmockuprtfrntqrtr-1.jpg
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floatsleftfrontqrtr-1.jpg
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floatsupperrightfrontqrtr-1.jpg
( 87 KB | 86 Downloads )
floatupperleftrear-1__1_.jpg
( 120 KB | 82 Downloads )
lftnacelledryingafterspritz.jpg

If God is your Co-pilot...switch seats...
Your attitude will determine your altitude!- John Maxwell
And ye shall know the truth, and the truth shall set you free. Jn 8:32
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Re: Grumman Goose G21a Lost foam process
Reply #1 - Jul 11th, 2017 at 11:55pm
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Wing is made with cracked ribs and double spars.  Here's the bones shots of the mockups.
Tom
  

( 77 KB | 89 Downloads )
Fuselageandempenages.jpg
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fuselagebonesinternalshot.jpg
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Fuselagetailfeatherswing.jpg
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mockupupperviewrtfrntquarter.jpg
( 118 KB | 90 Downloads )
rtnacellefoamremoved.jpg
( 54 KB | 83 Downloads )
rtnacellefoamloose2.jpg

If God is your Co-pilot...switch seats...
Your attitude will determine your altitude!- John Maxwell
And ye shall know the truth, and the truth shall set you free. Jn 8:32
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Grumman Goose G21a Lost foam process
Jul 11th, 2017 at 11:52pm
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Here's some pictures to replace the Photobucket debacle that left nothing but black squares.  Sorry for the loss of the details and notations on the pictures.

I saw a lost foam build on Small Flying Arts site before it went down by Tom Arnold.  I was intrigued and decided to give it a try.  I also decided to try the reed formers as Tom did.  So the reed was soaked over night and glued on the former locations of the foam to make the fuselage formers.  Once the fuselage was completed the whole fuselage was dunked in lacquer thinner to melt the foam out of the fuselage.  Worked quite well as the foam disolves and shrinks and allow the remains to be pulled out the nose of the fuselage.
Tom
  

( 81 KB | 109 Downloads )
Goosefoamandpatternsforsanding.jpg
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Goosefoamcorestart.jpg
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Foambalsareedconstrightside.jpg
( 26 KB | 93 Downloads )
Foambalsareedconstleftside.jpg
( 47 KB | 89 Downloads )
rearviewG21Goose.jpg
( 35 KB | 91 Downloads )
noseviewG21Goose.jpg

If God is your Co-pilot...switch seats...
Your attitude will determine your altitude!- John Maxwell
And ye shall know the truth, and the truth shall set you free. Jn 8:32
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