The Grumman F6F was never one of my favorite warbirds. In fact truth be told I'd always had a hard time telling them apart from the Wildcats. This somewhat bulbous looking fellow originally struck me as an easy to make warbird that didn't need to be so scale to "look the part." Currently I'm working on my fourth flyable Hellcat, so much for not being a favorite!
Hellcats were known to the Japanese Pilots as "The Big Blue Blanket" and something about this fighter is just fun. Maybe it's the fact that at peak production the Hellcat was being produced at a rate of about 20 per day from one factory, or maybe it's those humongous wings? Maybe it's the fact that the Hellcat was really the fighter that really hammered home the air war in the Pacific. While it wasn't be best performing or most spectacular fighter of the war, once one gets acquainted with it's history it's certainly hard to forget. I believe it's a classic warbird that everyone who is into RC WWII fighters should fly at least once.
My original rendition of this great bird was crude but flew incredibly well for what it was. The entire fuse was made via hair drying pink foam. Unfortunately it was so fragile that no matter how softly I set it down the pink foam would just fracture!
I ended up scrapping the original fuse and kept the wing for version II. This new version flew very well and its short comings didn't appear until I tried to roll if for the first time. The wings were so symmetrically imbalanced and the aileron throw so weak that it would actually lock upside down and you would have to get creative on how to right it!
Out of the hundreds of flights on that first hot wired wing, I was only forced to land upside down one time. I would still be flying this one today however it's motor (and nose) was totally destroyed in a training accident. (And I have not been able to get my father behind the controls since!) Either way, it paved the way for me to rebuild and advance my skills.
By the time I got around to building my next Hellcat my technique had advanced a long way. Using Goggles Sketchup this entire plane was modeled and designed for free.
F6F Hellcat Version III
I can't talk enough about Sketchup because for me it revolutionized on how I make my own aircraft. This program literally takes all the guess work out of the design process saving time and obtaining direct results.
The plans turned out spectacular, but take a look for yourself, to me this is well worth the CAD time spent.
Here you can see the printed paper from Sketchup, transfered to the foam it's a perfect fit!
When assembling it's easiest to make "cylinders" then glue them together.
While some can do this out of their head, and have a real talent for building, I cheat to obtain these results.
...and this model flew better in every way from the originals. I timed it at 3-4 seconds, flying from goal post to goal post, that's between 50 and 70 miles per hour. Unfortunately it suffered a similar fate after far fewer flights. The 400T clone motor I was using was way over propped. This eventually lead to a motor failure and subsequent crash. The airframe needs an over hall and I have never been fully satisfied with full length ailerons. -After flying both types I prefer scale to slightly enlarged, seems to me, this produces an overall smoother flight, and not so "snappy."
I may not be as good as some out these at making scale flying models, but I've still got a few tricks, though I've seen this done many times before, it proves at least I can can still carve foam at the end of the day. I believe it was J Morgan of rcgroups that put the idea into my head on vacuum forming with pink foam and Vaseline without any other additives. I've been able to pull multiple molds from a single carving, though for production something more durable would be called for. BTW if you haven't checked out any of J's builds, you should really make a point to do so, just look for threads started by him over there.
Not the greatest pull in the world, but for being one of my first, I couldn't complain.
For this thickness of PET-G, 275 Degrees F work perfect after heating for 3-4 min and will provide a much better pull then shown above, too bad I don't know the PET-G thickness. More on vacuum forming can be found at this web page.
This provides the durability of a common 2-liter bottle to the nose, although it still wasn't enough for me, but does protect nicely from the usual.
Finally in the paint shop!
One interesting aspect about the F6F is the motor mount, specifically the thrust angle. I always noticed the tendency, even in my not so scale build, that the Hellcat has to go into a harrier maneuver (tail dragging very low, almost in a hover, while moving forward in flight, yet maintaining a very stable -easily flyable, characteristic). On my third build I had to adjust the motor thrust angle downwards to keep it from climbing sharply at higher RPMs. Little did I know that the real Hellcat was designed with a 3 degree down thrust angle due to the zero incidence wing angle. This causes the tail to droop at lower speeds, while pulling it up at full power. Kinda neat how these real tendencys transfer to the hobby.
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