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New Plans!! 1/5th Grumman Goose G.21A

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Old 11-22-2011, 11:25 PM
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yamaharley
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Default New Plans!! 1/5th Grumman Goose G.21A

Hi everyone,

If you're interested in scratch building a Grumman Goose, then follow this thread! There will be updates!

I've been working on new plans for a 1/5th and 1/6th scale G.21A Goose for a short while now from Grumman's sectional drawings

Once the plans are completed, the model will be built and inspected by a qualified giant model inspector, test flown, and I'll let you all know when I upload the youtube vids. Then the plans will be available once it's actuallypassed as 'flyable and sound'

I'm designing the Goose as a rather simple quick build model so any relatively experienced modeller won't get a headache trying to build one. (As you don't score any extra competition points for construction complexity, you do score more points for scratch building!

It's all balsa and ply,so you'll have to do your own waterproofing if you want to use it as a true ampibian!! However it does have provision for retracts, or you can fill in the holes with dummy wheels as a permanent "water plane", so build it however you intend to use it! Allmodellers will prefer to set their model up their 'own way' so after some feedback Ireceived a while back, you'll have the option to finish it however you want with regards to landing gear / waterproofing !

I'm trying to keep the model as strong and light as possible but I'll have the cowls metal spun on the lathe now. The wings will dissassemble for easy transportation (one reason why I didn't go 1/4 scale at the moment because of my car size!)

I've uploaded a sneak preview of some 3D photos of the fuselage half completed! Take a squizz and let me know if you're interested!

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Old 11-23-2011, 10:58 AM
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Default RE: New Plans!! 1/5th Grumman Goose G.21A

How about some specs, wingspan, est. weight, power system planned, ect. looking forward to your progress.
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Old 11-23-2011, 03:51 PM
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Default RE: New Plans!! 1/5th Grumman Goose G.21A

At 1/5 th scale I am completing CAD drawings for a plan. As soon as it's ready I'll have it available from 1/6th -and eventually 1/4 scale also.

@ 1/5th scale dimensions: @ 1/4 scale dimensions: @ 1/6th scale dimensions:

Wing span: 117.6"Wing span: 147" Wing span: 98"
Length: 89.5"
Height: 19.8"
Width: 12.8"
Cowl diameter:9.6"
Cowl depth: 4.6"

I'll be either laser or cnc millingshort kits in the future after successful flight tests are complete.

Prototype 1/5th scale G.21 Goose will be powered by two 7 cylinder Seidel radial four strokes @ 70cc each with a 22" prop.


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Old 11-23-2011, 03:59 PM
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Default RE: New Plans!! 1/5th Grumman Goose G.21A

I'm in.
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Old 11-23-2011, 04:09 PM
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Default RE: New Plans!! 1/5th Grumman Goose G.21A

count me in
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Old 11-24-2011, 06:23 AM
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yamaharley
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Default RE: New Plans!! 1/5th Grumman Goose G.21A

Thanks for your interest!

I've added some more pictures to the original post. Nearly finished the tedious job of applying the stringers to the fuselage!

The wing and tail is the easiest part for me!

I've contacted a metal spinner company. Looks like it's cheap enough to spin metal on a lathe and make the engine cowlings that way!

A little birdy told me that Robart already makes retracts for this aircraft type?? I've seen some people go to the trouble of making their own (which Imay well do if I can't acquire any) but if you can just readily buy them off the shelf that's even easier! I've checked out their website but can't seem to find them?
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Old 11-25-2011, 06:22 PM
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Default RE: New Plans!! 1/5th Grumman Goose G.21A

yamaharley,

Does your CAD program allow for you to wind up with vector line art of the plans? For the benefit of having a kit laser cut?

If yes, it doesn't matter what size you build your model, because it takes nothing to reduce the size once the plans are in vectored format. You could offer cut kits at any size.

If all you'll wind up with is plans, I can honestly tell you, it's too big.

Sure, there'll be interest but not much. Couple of people will build the model, if that.

Gear? Robart won't even talk to you for a model that size. The gear they have now, that retract similar to the Goose, is the F4F. Very different, not even close. My guess is there's none available anyway.

You could offer a smaller model. A comfortable size that everyone can agree with. Many can enjoy it this way. Otherwise, it's you and only a couple of others.

Best advice I can give.

Charles

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Old 11-25-2011, 08:18 PM
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Default RE: New Plans!! 1/5th Grumman Goose G.21A

Good project. I will be following this with a great deal of interest, although for practical purposes, my needs would be met with a more modest size of 1/6th or even 1/7th scale.

Lets get that prototype flying!!!!
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Old 11-25-2011, 09:20 PM
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Default RE: New Plans!! 1/5th Grumman Goose G.21A

Indeed, very true Avaiojet & Wayne22. Yes the plans can be altered to any size at all to have the digital file exported for kit cutting.

If it's smaller you want, that's easy! However for the prototype my only reason forbuilding the 1/5th versionis to make use ofboth 7 cylinder radials.

I was initiallyinspired byacertainBeechcraft D-18 plan @ 147" span, and yet always wanting a Goose, I decided to base this one on a similar scale and thought it might attract some interest, but a smaller model is even easier!

You're right about the retracts! I'll custom Tig weld my own in the workshop, but I'll use ready made oleo struts at the correct length and go from there and make up brackets.
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Old 11-26-2011, 07:04 AM
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Default RE: New Plans!! 1/5th Grumman Goose G.21A

Quote:
Yes the plans can be altered to any size at all to have the digital file exported for kit cutting.
yamaharley,

I know of no digital program or file that can be exported as a vector line?

Sure, I have a program that takes bitmap art and turns it into vectored line art. But it does this poorly as does all programs that do this.

You must draw your plans in vectored format. Or you will have to have someone do a trace of each part to enable the part to be cut by laser.

I offer this service. Certainly, once the plan or parts are drawn, size isn't an issue, that's quick.

Radial engines are usually heavy for the power output. This model will sit in the water. Engine choice should be based on the absence of weight for power and not good looks.

Charles



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Old 11-26-2011, 12:19 PM
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Default RE: New Plans!! 1/5th Grumman Goose G.21A

Sounds great!  My plans are coming along great so far!

The plans can be altered to any scale   Thanks but I won't need to outsource any labour and I'll be painting my own graphics 

Radial engines do look great & are heavyt! Yes you're right! I've taken the weight vs volume displacement into consideration already :P

Ever seen the 4 engined Goose? It was a G-21C powered by 4 P&W  PT6A's. It sat so deep in the water with only 50% fuel and  only 4 passengers that the passenger entrance hatch sat 3" below the water line haha. The aircraft wasn't endorsed by Grumman and was just an expensive experiment.
If that was a real aircraft, the model at 1/5th scale won't sit anywhere near as deep in the H2O with radials :O

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Old 12-09-2011, 08:25 AM
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Default RE: New Plans!! 1/5th Grumman Goose G.21A

yamaharley, sounds like you've got a good project going! I'm interested in the 1/5 version as it seems to be good fit for the ASP FS-400 radial engines, one of which just happens to be sitting under our Christmas tree as we speak . Thanks for the good work and I'll be watching the thread.

Hal
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Old 12-09-2011, 04:32 PM
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Default RE: New Plans!! 1/5th Grumman Goose G.21A


Quote:
ORIGINAL: Avaiojet

yamaharley,


Gear? Robart won't even talk to you for a model that size. The gear they have now, that retract similar to the Goose, is the F4F. Very different, not even close. My guess is there's none available anyway.

........

Charles

Robart used to make 1/4 scale Widgeon gear...pretty close to the Goose. There was a 1/4 scale G&P widgeon kit that Robart had gear for, plus another giant scale Wideon that was kitted here in North Texas.

I am certain that Century Jet or Sierra Precision could custom make gear for any size Goose, for a price.

Nothing wrong with offering the plans at any size he desires. Remember, for every model built from a set of plans, at least 10-100 sets of plans gets sold to those who dream about building it. I have about 100 plans myself that I might never get around to building.... I agree that he should offer it in a more rational size, as well...but the nice thing about CAD is that doing so becomes a pretty simple scaling exercise, plus some new considerations for sizes of structural materials.
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Old 12-29-2011, 07:40 PM
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Default RE: New Plans!! 1/5th Grumman Goose G.21A

Thanks for all the private emails !

I took a holiday break over the christmas period, and in the new year sometime  I'll start uploading photos of the fuselage construction phase.

She truly is turning into a tubby model! If she eats too much wood, I'll have to put her on a diet !
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Old 09-02-2012, 05:05 PM
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Default RE: New Plans!! 1/5th Grumman Goose G.21A


Good day,

Is this thread still active?
Has anyone heard of the progress on that 1/5 goose?
Thx

al

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Old 09-09-2012, 03:07 AM
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Default RE: New Plans!! 1/5th Grumman Goose G.21A

Seconded, any news as there are lots waiting, even for just a set of plans!!
I was lucky as a youngster and used to fly "up front" in these things quite often. Even got the yoke occasionally!
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Old 01-18-2015, 10:55 PM
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I just found this thread and it's been several years since it was touched. Did these plans ever get completed? I'd be interested in a large scale Goose.
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Old 12-19-2015, 01:52 AM
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Hi Pilotbum,

That could have been me. Was it about a 1:3.5 scale goose? I am still working on that. My life got turned upside down and I have under estimated this Goose project. When done I will publish all. No worries there. Just got an email from centuryjet. They can do the landing gear and are interested. Sure it is a big plane. Not many people will build it for a variety of obvious reasons. But I think it is a beautiful plane.
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Old 12-20-2015, 06:20 PM
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Hey Joey,

I'm not sure it was you but I like the idea of a 1:3.5 scale! How is that coming? Any estimate on when it will be complete?
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Old 12-20-2015, 06:36 PM
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Hi Pilotbum,

No idea to be honest. The drawing should take me an other 1.5 to 2 years when I am dedicated to it. But that is all back home in Thailand. Right now I am in India so there is very little progress unfortunately. Also went bankrupt. Not a good thing with this kinda project...

Anyway, when I am back on it I will start updating on FG again.

Joey
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Old 12-20-2015, 06:44 PM
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Hi Joey,

Thailand? India? You must be a contractor? Yea, sounds like your life was turned upside down! Hope things are looking up for you?

What's FG?

Randy
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Old 12-20-2015, 06:54 PM
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Hi Randy,

FG is Flying Giants. Things are starting to look a little brighter but not quiet there yet.
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Old 12-20-2015, 07:01 PM
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Is there a thread already started on FG?
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Old 12-20-2015, 07:07 PM
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Hi Randy,

I just realize that I misunderstood your first message. My thread is on FG this is someone elses thread. I thought you were referring to a thread you found on FG. Hence my reply to you. Not sure why that was in my head. Anyway. That thread too has not been touched for well over a year for reasons outlined before.
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Old 12-20-2015, 07:13 PM
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Ha! I don't care! Your Goose sounds like a cool project... I'm going to go look for it! The Goose has long been a favorite of mine!

You wouldn't happen to have the URL on FG would you?
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