Giant Scale: Grumman Goose G-21A

[John Weekes]

Who says building is dead!!!! :D

Ok...after much pressuring, I'm starting a post of my latest build project...a giant scale Grumman Goose. Starting in my childhood, this has always been one of my favourite a/c.

I looked all over the internet but could not find giant scale plans for this design. There are GS plans and kits available for the Widgeon, Mallard, and Albatross...but not the Goose...at least none that I could track down.

So...my son Alex (18) and I decided to have a go at designing and building from scratch (this is not my first scratchbuild...but I haven't done many from a blank sheet of paper). Really, it's Alex designing the airframe, using AutoCAD, with me giving direction on structure, points for reinforcement, etc. (Alex does not fly). We are using a combination of full scale 3-views, full scale photos), and a 1/9 scale RC version (.40s), and other similar designs as guides.

It's a fun father-son project...but somewhat anxiety provoking considering all of the uncertainties involved. The dimensions and configuration is exact scale...but the model is a "fun" scale...maybe I'll call it the "Loose Goose"! ;)

Anyways, I'll try to take some pics to upload...but to peak you curiosity, here are the design specs:

Wingspan (3 piece): 96"
Length: 75"
Scale: ~1/6
Engines: 26cc gas (x2)
Fuel capacity: 32oz.
Anticipated weight: 22-26lbs.

Materials:

Fuse - door skin ply, lite ply, balsa, fibreglassed with 3/4oz cloth and Zpoxy fnishing resin.
Tail feathers - sheeted over balsa sticks, fg
Wings - foam and balsa sheeted, 6' aluminum tube spar
Engine cowls - custom (i.e., homemade) fg and epoxy
Landing gear - n/a - although I may retrofit removable fixed gear if the damn thing flies.

Construction to date:

Tail feathers are mostly done...just a bit more sheeting and shaping, then it's time for the epoxy and glass
Fuse ~60% completed. Fuse sides, bulkheads, hull sheeting completed...upper nose bulkheads in place...planking partly done (hate this part). I still need partial bulkheads and sheeting for the aft section of the fuse.
Cowls - I've made a couple of beta examples using Zpoxy and a combo of 2oz and 5 oz cloth. Suitably sized plastic salad bowls (8.5" dia.) from the dollar store as molds (lots of car wax and PVA release agent).
Wings - no construction so far...just gather parts and thinking through the design.

This is a really BIG airplane...the size of the fuse (chubby) combined with 2 8.5" engine cowls up on the wings will make it look really imposing. I doubt I'll have it ready for the ORCC Concours d'Elegance in April...but I am aiming to have it completed for the ORCC Float Fly on Saturday June 23rd. ...It won't be a Beaver (2007 is the Beaver's 60th anniversary and the theme of this year's float event)...but hopefully Aurele won't mind...:)

Comments, questions??? Yes, I'll post some pics...

John

[Mark Winstanley]

pictures - we need pictures!!

[Tom Hastie]

See attached

[Tom Hastie]

This is a really BIG airplane...the size of the fuse (chubby) combined with 2 8.5" engine cowls up on the wings will make it look really imposing.

Now... the question is... is it big enough to drop off Arnold Schwarzenegger on a tropical island along with enough of his kit to take out the entire Cuban Army. :rolleyes:

[John Weekes]

Yah, I'm tempted to include a little miniature of Rae Dawn Chong at the controls...;)

I took lots of pics last night...but my son got home late from his class at Carleton and didn't get a chance to do the uploads....guess you'll just have to wait some more...

I continued with planking the upper nose section...a somewhat tedious process...and something that I'll be doing a lot more of before this model is finished...back of fuse, engine nacelles, etc.

...On the bright side, the nose really does look like a Goose now.

Mark: ...Actually, this big bird is constructed from a lot of the materials I got from you before you moved...door skins, wing foam, etc.:)

John

[Dave_Sawatzky]

John, I applaud your efforts. Scratch building a giant scale aircraft is something that most of us would not have the guts to do. I guess you've had enough exposure to large scale models that you have a good idea where and how to build in adequate strength without being overly heavy.

Knowing your building ability, I have no doubt that the resulting aircraft will be gorgeous and probably fly great too.

I look forward to seeing the photos as construction progresses.

Did you ever get to fly your giant stinger?

[John Weekes]

Hopefully, Dave... :)

Thanks for the kind words...so far the model is shaping up nicely and should look good when it's done...

Hmmm...I guess you're right...there is a considerable investment to build a model of this size and complexity (particularly, a multi-engine flyingboat)...with some risk that it won't fly at all...maybe I should have chosen something more straightforward...:eek: Nah...it'll fly...(I hope).:o

Further delays on the pics...my son wasn't able to get to it last night...maybe tonight.

...This big bird really does exist though...:o

Yes, I did get the Stinger flying last summer...too bad you missed it (you could have had a go at the controls). It flies just like everyone said it would...very predictable, reasonably aerobatic. Next summer will be the season to really start flying it. Really, it flies like a trainer...super easy to land. I found the lg pretty flimsy though (typical crappy Lanier materials - great designs, lousy kits)...and have replaced the stock gear with a hd version I got from the guy in Tenn. who I get my aftermarket fg parts from. ...These gear are a little heavier and a lot stronger.

...I hope the Goose flies as well...we'll see...

Great to hear from you...how are things in Iowa? ...Still flying out of your backyard?

John

[cgroves]

What, no stinger skis?;)

[John Weekes]

Here are the pics....what do you guys think?

John

[Mark Winstanley]

looks good. Yes I recognise the plywood! It seems as though you are getting into giant scale in a big way (forgive the pun!). Laser, Singer and Goose! Keep it up. I am just putting a lage Stearman together foe a 120 four stroke not to mention several small electric models. Hopefully I will get to fly them all this year. Today is bad as there is aterrible wind/rain storm. Just as well I have to be at work earning money to pay for my addiction!

Mark.

[Sev Fontaine]

That looks great John. I really hope to see it fly sometime this summer.
Are you planning on putting wheels on it?

637

[John Weekes]

I hope you get a chance to see...or fly the Goose too, Sev!

Mark, I also have an ancient 33% Byron Pitts S-2A that I got from Brian Wattie a few years ago. ...It has been gradually undergoing a MAJOR refurb that has involved completely stripping the fibreglass off the foam...I've just located a suitable gas motor for it...so it might go onto the board after the Goose is airborne...probably early summer (who knows...).

These big birds sure do take up a lot of space though...those guys who have seen the (small) size of my workshop and storage area will know what I'm talking about...

Tonight I am going to shape the nose cone on the Goose to really make it look like a Grumman Goose...then do some internal work to the tail section before planking. I am going to install a tailwheel and bracket that I can exchange for a water rudder (the full size Goose does not have a water rudder). I don't plan on putting retracts on this model...however, a retrofit might be possible down the road. I am engineering the centre section of the fuse to accommodate removable fixed gear...I can take advantage of the internal reinforcement needed within the fuse to support the wing attachment. ...Hard to explain...but I'll add some pics when I get to this part. I've got the building sequence scoped out in my head...some parts of construction in the fuse need to wait for the wing.

I think Alex and I will likely cut out the foam for the wing this week-end. I can hardly wait to see the whole airframe mocked up...I'm not sure if these pics give you a sense for just who big this model is...the "chubbiness" of the fuse/hull really accentuates its size...

This is really a fun project...it's exciting to see the model take shape. :D More updates to follow...

John

[Tom Hastie]

Hot Stuff..

Lookin' really good. How did you make those cowls? Almost looks like you laid up the fiberglass in a couple of salad bowls :) I think there should be a picture of you and Alex each wearing one on your head.

Here's hopin she floats. I thinks we could do some taxi tests from the quarry behind the treeline.

[Dave_Sawatzky]

Great looking job on the planking. That is time consuming, but you get those beautiful compound curves. I am also interested in hearing how you made the cowls. Keep the pix coming.

If it is successful, maybe someday this design will end up as a kit?

[John Weekes]

Actually, I thought the two cowls paired together resembled something else...:rolleyes:

I have confidence that it will float...the full scale Goose sits pretty low in the water...we'll have to see what this one does.

I layered up the planking with light filler...it'll take quite a bit of sanding but the nose section will come out lookin' good. I'm going to try to add the nose cone tonight...lots of shaping there...but it will really look like a Goose.

No, Dave, this will NOT be a kit. It's a Weekes custom one-off. :)

For those interested in the Goose, check out www.grummangoose.com. Also, Alex found the company that is now reproducing the Goose. www.antillesseaplanes.com. A mere $1.3M USD gets you a modern radial version... $900K more gets you a Goose with turbines... I think I'll put in an order...:D

More progress pics to come...

John

[Soclarke]

Nice project John! Have you picked a color scheme yet?

I think the turbo prop version is ugly! :eek:

[Tom Hastie]

looks good. Mark.

That looks great John. I really hope to see it fly sometime this summer.

Hot Stuff..

Lookin' really good.

Great looking job on the planking. That is time consuming, but you get those beautiful compound curves.

Nice project John! Have you picked a color scheme yet?

See? Isn't this better than building in your dark dank basement with no one to inflate your ego and motivate you to continue?

[John Weekes]

Yah, yah...the accolades are great, Tom...

Scott, I'm thinking of replicating the RCMP livery on the Goose at the air museum - C-FMPG. ...Pretty basic white with dark blue trim....or a variation on this theme (...a scheme that includes a lot of white). ...However, there are some incredible schemes out there on the net for the Goose that I have thought seriously about doing...

...I agree with you totally about the ugly turbo prop conversion...I don't like it at all! ...As you could see, my model will definitely be radial cowl(s).

...We attached and shaped the nose last night...now it totally looks like a Goose on the front end...I'm tempted to build up around the cockpit area but really need to wait to see where the wings sits before I start committing to a certain structure. This is an example of having to always think a few steps a ahead when you are scratch-building.

Hopefully, we can cut out he foam for the wings in the very near future. I can't wait to see the model all together on the basement floor.

Thanks for the feedback, guys. I hope my project inspires others to consider their own scratchbuild project. It is really exciting to see your design take physical form and come to life...

I would caution that it is definitely a challenge, there is some risk (that you spend a lot of time and money on something that flops), and it is a lot of work...I have always really respected the local guys who get involved with designing and building from scratch...Gerry Pronovost, Aurele Alain, Ken Park, Brian Wattie, Steve Gutz, Tom Hastie, come to mind as examples of just some of the local guys I know who have done this...see there are quite a few...

If my Goose doesn't fly maybe I'll donate it to the Canada Aviation Museum so that it can sit beside its big brother...

John

[Tom Hastie]

I don't think the Turbo prop conversion looks that bad... it just doesn't look like a Goose. If you saw it in isolation, I bet your first impression wouldn't be so bad.

I think it looks better than the Turbo Beaver that uses the same engine. It's an impressive engine when you consider that it was designed in the late 50's and it's now the most popular turbo prop engine in use:

http://www.pwc.ca/en/0_0/0_0_1/0_0_1_3_2.asp

http://en.wikipedia.org/wiki/Pratt_&_Whitney_Canada_PT6

All the PT-6 aircraft tend to look similar since it's such a long/skinny engine. I think the long nacelle accentuates how much up thrust is on those engines when you look at the side view. John, are you putting upthrust on your engines? It might be a good idea to help keep the nost from digging in when taxi-ing.

Tom

[cgroves]

Naw, the only place a PT-6 belongs is in the nose of a PC-6, PC-12, or a Turbine Maule (Otherwise known as the express elevator). I have to agree they don't compliment the lines of a Goose.

[Tom Hastie]

This Post is to give me one more post than Corey.

[John Weekes]

Here are more pictures guys. This is how this big bird looks presently...

1) Nose block is now attached and rough-shaped
2) Tail wheel and internal assembly in place
3) Rear underside of fuse is planked (1/8"x1/2" strips)...easy to work with (soaked) and to sand.
4) Fuel tank support and servo tray installed. BTW, the fuel tank capacity is 950cc...that's almost a litre (twin 26cc powerplants)!!!
5) Fin assembly is installed; tailplane basic assembly is completed. The base is made from 3/8" ply (lightening holes) and bals since it supports both the rudder AND the horizontal stab and elevators. Brass rods for bracing (not shown but to scale). I'm hoping that this is over built...I guess we'll find out eventually...:o

[John Weekes]

and they continue... btw everything you see in the pic now weighs in at 6.5 lbs...there's probaby still 1-1.5lbs additional materials and hardware to go on.

Anticipated total flying weight (dry): ~22lbs.

I just have a bit more work to do on the fin/rudder, then we'll be ready to move onto the wings. At this point, I do not want to close in the upper back portion of the fuse. I need to see where the wing finally sits in order to mate the semi-circular upper section with the way in which the fuse fairs into the wing. Also, I want to fully assemble the model and get some idea for balance...I'd rather not have to butcher the fuse to add lead if I can avoid it!

...IMHO, it's really starting to look like the full size bird...I can hardly wait to see model this take flight off the club pond at the June ORCC Float Fly!!

...And I'm going to speak with the owner of the trailer park where we have our trailer to see if they'll let me fly off the lake (power boats prohibited)...

John

[Tom Hastie]

Hey! That sure looks like a goose.

Kinda scary figuring out which parts of the plane to "close up" when, eh? I know what you're going through ;)

I'll definitely be coming out to the float pond when it maidens!

Have you got anything done on the wings? I want to see it with wings on!

Tom

[John Weekes]

We'll be starting with the wings shortly, Tom...probably within the next week or so. ...Still need to think through the sequence of what to hotwire first...servo cavities (x6), wing spar tube, etc. The wing will be foam with balsa sheeting...3 pieces, just like your Mossy. The centre section will support both motors and about 1/2 of the flaps. The outboard panels will have the rest of the flaps, ailerons, and the sponsons. As a result, the main chunk of airplane will be pretty big going into the van! :-)

I'm not 100% decided on how we'll attach the centre section to the fuse, that's why I'm leaving the fuse semi-finished at this point.

If I'm going to fly at the float fly on June 23rd, I'll need to have the model flyable by mid June at the latest (MAAC rule: can't maiden a new model at an event).

...A lot of work left to do. The fuse and tail will be glassed (3/4oz cloth)...I've decided to expedite the construction by using Ultracote on the wings.

QUESTION: Anyone know where I can get 4" thick white bead foam in Ottawa? ...I thought I had some (from Mark Winstanley), but the stock that I have isn't thick enough. Home Depot doesn't have it...haven't checked Rona yet... I need 4"x2'x96". It's a big wing...

Hope to see everyone and their crap (err...I mean quality model airplane merchandise:p ) at the ORCC auction, Tuesday evening at McNabb Community Centre. Bidding starts at 8PM.

John

[John Weekes]

Well, as things often go, I haven't had much time lately to work on the Goose...work, family, and repairing smashed airplanes. :mad:

On the positive side, I will bring the Goose to the next ORCC meeting and talk a bit about how we (my son and I) approached designing and building this kind of unique giant scale model from home.

Hopefully, we'll be able to get back on track with the Goose build (wings) soon.:)

John

[Tom Hastie]

Looking forward to seeing the Goose in person.

I'll be bringing in my Mosquito. It'll be a scratchbuilding extravaganza.

With any luck we'll put some of those BARF-building lazy bums to shame and get them to take razor saw to balsa.

Tom

[Soclarke]

Who's plans are you building from Tom? Ivan Pettigrew's? Where are the photos?

[Tom Hastie]

It's actually my own design. I started from Brian Taylor 72" plans that I scaled down to 55" and then redesigned from his bulkheads and 3-view. There's not much left of his original plans in it.

I've been doing a fairly detailed build thread on RCGroups here:

http://www.rcgroups.com/forums/showthread.php?t=440058

And now back to your regularly scheduled Goose thread.

Tom

[6cuda6]

Tom please tell me that fuse is not sitting on a full size freezer.....cause if it is i want to see it fly!!! Just kidding, i want to see it fly anyways.....keep the pics coming, that is awesome!!!

Jeez, the skills some guy's have.....hope your passing them on as you go....

Later, Dean

[John Weekes]

Hey Dean...actually it's me, John, who's scratch-building the big Goose. Tom is scratching a DeHavilland Mosquito.

...No, the freezer isn't fullsize...however, the model is still pretty BIG. The wingspan (when built) will be 96"...the fuse is 75"...when I stand it on its nose it is taller than I am (5'10")! I estimate that it will weigh in at about 22-23lbs ready to fly.

If you belong to the ORCC you'll have a chance to see one or both of these models at our next meeting on Tuesday. I know Tom's bringing the Mossy...and I'm going to try to make it...although work-related things are pretty busy for me this week (infringing on my building time!).

Glad you liked my big Grumman!

John

[6cuda6]

Sorry John.....got confused....been painting the bed room...lol.....tuesday, hummm might be able to make that one....we'll see....but i do want to see it fly, way to cool!!!!

Dean

[John Weekes]

Dean, you should go to the ORCC meeting on Tuesday night if you can. Tom Hastie's Mossy is a masterpiece of design, engineering, and construction techniques. He's put a tremendous amount of time and effort into constructing this awesome model. ...Anyone who has tried designing and building their own model knows just how much thought and effort go into this kind of project.

Like I said, I'm going to try to make it...but $$ calls so I may need to work. If I can, I'll be there too along with the Goose.

I hope you can make the ORCC's big float fly on Sat. June 23rd. I'm aiming to have the Goose airborne then (since it kinda looks like a boat with wings!). Aurele Alain, the organizer, has lots of fun planned for us. I went last year...I didn't even have anything to fly...and I had a great time. Even if the Goose isn't airworthy, I'm still bringing something on floats to fly!

...Ok, back to work (unfortunately, not building...).:(

John

[Mark Winstanley]

John; you can get 4" thick foam across the river in Hull. I cannot remember the name of the place - it was a long time ago that I went there - but Dave Asquini knows as he told me where to go (he does that a lot!). It is a big builders yard as I recall with a retail outlet at the front. They sell it in 4 ft by 8 ft chunks and will cut it any way you want providing it is a straight cut with a circular saw.

Best of luck.

Mark.

[John Weekes]

Hey Mark...remember we talked about this?? ...I followed up with Dave who gave me further directions...I guess you've been drinking too much German beer over there in Cologne! ;)

Anyways, the outfit is Pilon's or "PAL" (sign has 3 trees with the letters PAL in front) just down the road from Multi-hobby. They had two 4'x4'x4" slabs available that I picked up. Enough extra in case I mess up...

Thanks for the lead...and I hope your memory returns to normal soon... :)

Now I just need the time to set things up the cut out the wings for the Goose. Maybe this week-end...

John

[Mark Winstanley]

Thats the place!!

[6cuda6]

John,

What up with the Goose!!! No progress report or updates.....did the" feathers get plucked "from the bird till fall??? [Sorry i just couldn't resist:D ]

Later, Dean

[John Weekes]

...Been busy building (and repairing) other models.

...Recently, my son Alex and I resumed work on the Goose. I have cut out the foam cores to the wings and we are presently engineering the motor boxes that will extend forward from the leading edge of the wing. We plan on building up the engine nacelles around the motor boxes so that I can remove them to shape and final sand. They are both large...the diameter of each fibreglass cowl is 8.5"...and the nacelles extend quite a way back over the top and bottom of the wing. This (for me) is tricky stuff...the motors on the Goose are also angled upwards and extend quite far forward from the wing. Considering that I am using 2 26cc gasoline engines, this is a lot of metal/weight forward. We'll have to see about the CofG.

I'll post some more recent pics as real new construction takes place (right now the wings are just big foam slabs with cut outs here and there).

For those of you in the ORCC, I am bringing the Big Bird to next week's club meeting (Tuesday, May 1) so you can see just how big this amphibian really is!!

John

[John Weekes]

Again...sorry no pics...however all will be revealed at Tuesday's ORCC meeting.

We cut out the main wing panels last night...geez...it sure helps to have an 18 year old son to help with the cutting! I own a hotwire system that my uncle built for me years ago...he doesn't fly models but was a technician for NRC...can pretty much construct anything mechanical or electrical.

Anyways, we used Mark Winstanley's cutting bow since my 2 bows are not large enough for Giant Scale. Thanks (again) Mark...

The foam cores came out so well that they almost look machine made! ...However, I tried cutting the centre section core on my own (3-piece cores) and buggered it up...D'oh! No matter...good thing I purchased extra 4" thick foam from PAL Lumber. By Tuesday we should have the wing tube in place so that I can sit the Goose up on its cradle in one piece for folks to have a look at...or at least that's the plan.

My son just finished his exams at Carleton and is busy during the day designing Goose parts in AutoCad. ...He is my secret weapon for this build project! :D

BTW, he's looking for a summer job...Anyone out there need a super bright 18 year old mathematician who is also pretty good with computers and all kinds of software??? :)

John

[Tom Hastie]

I snapped a couple of shots of the Goose at the club meeting last night.

For all you guys who didn't make it out, it's really impressive. I can't wait to see come nacelles on this puppy!.

Enjoy,

Tom

[John Weekes]

My son and I are back designing and building the Goose. We're focusing attention on the centre-section of the wing...which also houses the engines/nacelles. The outboard panels (w/sponsons) are removable.

I've decided to power this big bird with 2 GRPro 26cc engines. Andre Blais (ORCC President) is the Canadian Importer/Dealer. These little puppies come complete with electronic ignition, inverted Pitts mufflers, and engine standoffs. The Walbro carb is mounted on the back of the crankcase making the motor very streamlined (not that it matters with the Goose's huge round fg cowls!).

I've purchased one of these motors (might also put one on my KMP Hurricane) and have been running it on the bench. Awesome! ...The motor starts beautifully, has loads of power and is very light. I figure I will save ~4lbs by switching to the GRPro vs. the clunky Robin engines. Anybody wanna buy a couple of 26cc Robin engines really cheap???

Anways, over the summer 0Alex (my son) designed the engine mounts, nacelles, sponsons, cockpit area, and turtle deck...so I need to get the lead out and get building!

I have the engine mount boxes (1/4" ply) partially built this week.

I'll post pics when there's been significant change in the way this big machine looks.

...I might also drag it to the Zone Meeting later this month for display.

John

[Sev Fontaine]

John
Good to see this project back on the building "platform". :rolleyes:
I cant wait to see it all done and ready for covering. I'm sure it will be very impressive.
Best of luck with the build!

Note: I've been building quite a bit recently. 3 new planes built from kit since NEAT fair in September. I now plan on continuing work on the scratch built 36" Pitts Python.

Sev

[John Weekes]

Lots of progress on the centre section and outboard panels of the wing. I will post pictures soon.

Also, the GRPro 26cc is breaking in nicely on my Giant Stik test platform. I think x2 these motors will have lots of power to pull this big model up out of the water.

BTW, Andre Blais is importing these motors...check mine out at the ORCC field. Starts easily (electronic ignition)...seems to run great as the motor breaks in.

Pics soon...

John

[CaptAhab]

Greetings, Any progress on the Goose ? I'm looking for some good 3 views to start one for myself. Can anyone help me out ?
I purchased one from Bob's documentation but there has to be something better out there. Thanks if any of you can help !

Duane

[John Weekes]

Hey Duane...I PM'd you via Calmdays.

We have the 3-views electronically. My son and I also have our model drawn to scale in AutoCad if you have this software.

We haven't worked on it for a while now...maybe this winter.

Email me at - drjohnweekes@hotmail.com and we'll dig up the link or send you the file.

Our model is 96" wingspan...twin 26cc gassers. Probably 22-24lbs dry. Of course, it can be scaled to any size in AutoCad.

Hope this helps...
John