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Old Dec 06, 2011, 09:02 AM
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Pål's Avatar
Ljungbyhed, Sweden
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Warhead's Grumman Goose 33"

I'm nearing completion of my Grumman Goose, based on Warhead's brilliant free plans. I chose to scale down to a little over half the original plans, so that I could use 6mm and 3mm depron instead of 1/2" and 1/4" foam. I planned on making it really light and using small motors, but now that the numbers add up I've had to increase the watts.. I'm still hoping that it will fly reasonably slow.

The construction is mainly depron, but most shaped parts are pink foam. The canopy assembly/hatch is made entirely out of balsa and thin plywood. The wing beam is really light 6mm balsa, and the cowls are ordered from sparky. The whole model is glassed with wbpu, with 50g on the fuse and 25g on the wing and empennage. I'm not quite sure which primer and paint to use, as I have never painted an entire model before. Also, I need to decide on livery..

Just wanted to show you some pictures of the construction, and hopefully get some tips about finishing and flying. The original thread and plans can be found here: http://www.rcgroups.com/forums/showt...+grumman+goose

Lastly, I want to thank Warhead for posting his work and plans free of charge!

/Pål
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Old Dec 06, 2011, 09:03 AM
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Ljungbyhed, Sweden
Joined Apr 2004
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Building the wing

Building the wing is simple, as the top is flat (no dihedral). The skins are cut, the spar is glued to the top skin and the formers are added. Add servos and secondary spars + aileron capping and glue the bottom skin on. Sand LE and glue a light balsa LE to it. Glue on wingtips and sand to shape, done
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Old Dec 06, 2011, 09:38 AM
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Building the fuse + cockpit

The fuse is pretty straightforward, but has many parts. I had to slightly extend the middle floor (cargo floor) to fit, but other than that, everything slotted in nicely. The cockpit area was built 'on site' to fit well, but is removable with a magnet. The important part here was to get the windows placed right, and then build everything else around them. This part was later hollowed out with a dremel, but still weighs quite a bit.
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Old Dec 06, 2011, 09:50 AM
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Building the nacelles

The nacelles were turned on a wood lathe and then carved hollow to fit the wing and motor supports. I haven't decided on how to fasten the cowls yet, as I need to change the motor mount to fit the new motors, which arrived today
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Old Dec 06, 2011, 11:19 AM
Two left thumbs
Muncie, IN
Joined Sep 2006
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Very nice!

Geoff
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Old Dec 06, 2011, 01:20 PM
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Ljungbyhed, Sweden
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Thanks Geoff,

How is your Goose coming along?
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Old Dec 06, 2011, 04:20 PM
What's 3D?
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Australia, WA, Ellenbrook
Joined Feb 2008
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that is a great looking build mate, Gotta love a Goose!

Cheers
Craig
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Old Apr 02, 2012, 04:30 PM
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Chicago, IL
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Wow! How did I not know about this? Working on the 1/10th scale one right now.
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Old Apr 06, 2012, 09:37 AM
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Pål,

Since you are farther along than I am, I thought I'd share with you my thoughts for attaching the wing to the fuselage. I planned to use a tongue on the trailing edge of the center section, that will simply slip under the turtle deck. To hold the front of the wing down, I planned to install a couple of vertical tabs that will align with corresponding hard-points (ply circles) embedded in the cabin bulkhead. Then I will insert pins through the tabs and hard-points to hold it together. The cockpit hatch will then go on and hide the pins. Simple, no bolts will show, and no tools required at the field.

Warhead
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Old Apr 11, 2012, 03:54 AM
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Ljungbyhed, Sweden
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Hello Warhead,

Nice solution! I also used a tongue on the trailing edge, but didn´t make the forward attachment as clever as yours. I have a simple wing bolt that goes through the upper skin. The livery I have chosen sort of hides it, so I´m fine with it.

My Goose is ready to fly, only thing that is missing is its N-number and some small markings that I need help to make (thinking of ordering from Callie). I am currently away from home, but I will hopefully have time to post some pictures of it and maybe also do the maiden voyage/flight when I return home.

Pål
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Old Apr 11, 2012, 09:03 AM
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Can't wait to see it. Are you painting right onto the foam or using a covering material? Are you cutting windows into the cockpit?
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Old Apr 12, 2012, 03:56 AM
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I painted right onto the wbpu/glassfibre, but I wasn´t exactly happy with the results. The wbpu turned slightly soft and it was hard to get nice cuts in it after the paint went on. Also, the weight increased dramatically when painting it, but with the new motors I think I am good. I am travelling home on saturday morning, and have the weekend plus monday free, so hopefully there will be time and weather to test it out.

The windows was painted on with satin black. They look nice, but not as nice as yours. Maybe I will cut them out afterwards if I want more details. Do you still have the files for the cockpit print-outs?

Have you started thinking about throws? I´m not so worried about the ailerons, but the elevator is quite large and I am slightly afraid of having too much throw on it. It seems to have very good authority on a static test with the motors running. Are you going to have differential thrust on yours?
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Old Apr 12, 2012, 08:24 AM
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I do have the cardstock cockpit file and I'll post that on my thread. For throws I'll probably go with 20deg on everything for the maiden but I'll use 50% exponential so she's tame near the center. I think I'm going to use newspaper and 50/50 Titebond to cover mine. Hopefully that won't be too heavy.
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Old Apr 12, 2012, 08:27 AM
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Yes I'll use differential thrust for taxiing but switch it off in flight.
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Old Apr 15, 2012, 07:40 AM
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Semi successful maiden

Flew observers seat from Oslo to Stockholm yesterday in a B738. In Oslo we had blue skies and beautiful spring weather, but in Stockholm there was poor visibility due to fog and snow. We did a CAT 2 with autoland and saw approach lights at around 150´ which was a new experience for me. The taxiways were covered in about 4-6 inches of snow, so apparently they were surprised to have snow this late.. However, I saw this as an excellent opportunity to maiden the Goose on snow, as I have very limited experience in flying from water.

Later during the day, the fog lifted and the cloud cover disappeared. I went to a football field and started with some taxi runs. The Goose got pretty light at low speeds, which was very nice. Then I did a takeoff, but dropped the right wing and put her down again. Trimmed in some rudder (differential thrust, as I don´t have a rudder yet) and gave more power on the next try. It flew, but I had to fly with the left wing down and in a heavy sideslip to maintain direction. It was hard to maintain the slip and speed, and the right wing dropped again. I called it the day, happy that the Goose lifted, but not so happy about the yawing/slipping tendency.

Apparently, my vertical stab is mounted at an angle. I have now started to cut out a rudder and are going to complete this before the next try. I´m very satisfied with the takeoff speed and ground handling, so hopefully it will be a great flier when everything is sorted out. It bothers me that I didn´t spend more time lining the tail up, but that is the past and it would require a major rebuild of it to straighten things up. The rudder will hopefully make things better.

Unfortunately, I don´t have a lot of spare time in the weeks to come, so the next flight has to wait.

/Pål
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