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!
@ 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.
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?
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
Lets get that prototype flying!!!!
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.
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
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
Hal
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
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.
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 !
I was lucky as a youngster and used to fly "up front" in these things quite often. Even got the yoke occasionally!
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.
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
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.
You wouldn't happen to have the URL on FG would you?