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Old Oct 20, 2009, 11:21 AM
'Cobra Fan - P-39 & P-63
Rengine's Avatar
Fort Collins, CO
Joined Aug 2004
323 Posts
Build Log
H E L L - B E A R -- warbird/3D tribute 60" span, 3.5 lbs AUW -

The HELL-BEAR - a tribute to warbirds and 3D too

FFF - Packing Tape - Hot Glue
-- 60 inch span - 48 inch fuse - est AUW at 3.5 lbs - 56 ounces

Started on a new one this last Sunday - kind of like a P-47 Jug & Hellcat F4F combo. After my "Corbra" success (and subsequent crashes and trashing) I wanted to use a similar type of fuselage buildup for this one. It's easy to do, just takes some time as I have to cut each part as I build and test fit.

I spent about 15 hours building on it Sunday and made great progress. Going to be using Hacker A30 12XL motor, 4s1p 2200 mah batt pack, 40 amp esc and 4 full size servos. This combo worked great on the "Corbra" - pulled hard and fast with a 14x7 prop. These wings are damn near flat (the 'airfoil' must be put in quotes as it's the thickness of a single aluminum arrow shaft ). Should be plenty fast and without all the annoying lift.....

time for the photos to do the talking

Enjoy!
Mark
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Last edited by Rengine; Oct 26, 2009 at 10:02 AM.
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Old Oct 20, 2009, 02:01 PM
Registered User
United States, OH, Troy
Joined Jan 2008
77 Posts
Looks a little like a F-8 bearcat.
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Old Oct 20, 2009, 02:08 PM
A&P Mechanic
may-day's Avatar
San Antonio
Joined Mar 2005
326 Posts
cool
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Old Oct 20, 2009, 02:10 PM
CMelton
cmelton11's Avatar
USA, NC, Burlington
Joined Jul 2009
320 Posts
what size are your formers that is a cool looking build
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Old Oct 20, 2009, 03:29 PM
A&P Mechanic
may-day's Avatar
San Antonio
Joined Mar 2005
326 Posts
great size. Not way too big and difficult to transport, not to small and wind bound.

Dave
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Old Oct 21, 2009, 10:28 AM
'Cobra Fan - P-39 & P-63
Rengine's Avatar
Fort Collins, CO
Joined Aug 2004
323 Posts
Save $200 To $700 On Each Plane- Build With Fff!

Thanks for the nice comments guys!

Got some more done last night on the - uh...Warbird! maybe think up a name today...Helljug...HELLJUG extended fuse....racing HellJug ? Pattern Warbird...

Anyway - got the formers done and wings built - gotta mount the servos and such...now the design phase is done and the location of batt & servos comes into play as I maintain the Center of Gravity at about 25 - 30% of wing chord. I do the batt placement last to finalize the proper CG.

So I build the fuse without concern for placement of servos, recvr, batt, etc - and just cut a hole in the foam later for those. Makes building without a plan much easier.

The full fuse with wings on and the Hacker A30 mounted is only 1.5 lbs. Excellent...should hit 3.5 lbs AUW easily enough.

Making formers is easy!
First glue on the long horizontal former (each side has one that follows the thrust line), as they are used as a guide for the rounded vertical formers.
Once those are in place, just cut a 90 degree angle into any scrap foam piece big enough to work. An acrylic drawing triangle is what I use a lot for a scratch build like this.

Wherever you want a former. hold the scrap piece with the 90 degree cut up against the vertical beam/spine and the long horizontal former and use a pen to mark where the former should be cut to fit. Then lay the circular device (in this case stovetop burner cover) on the piece of foam and cut it. very hard to describe - but so easy to do....

enjoy!
Mark
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Last edited by Rengine; Oct 21, 2009 at 11:13 AM.
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Old Oct 21, 2009, 10:57 AM
Master Crasher
zultone's Avatar
Fletcher, NC
Joined Oct 2008
681 Posts
Looking very sharp. I like it.

I have not figured out how to make good formers... All of my builds have been boxes because of it.
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Old Oct 22, 2009, 02:32 AM
TJC
Crossweave king
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Cambridgshire in England!
Joined Jan 2007
552 Posts
Nice build. I'm a big fan of just letting a plane design itself as you build. Capturing the spirit without following any specific design.
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Old Oct 22, 2009, 08:44 AM
'Cobra Fan - P-39 & P-63
Rengine's Avatar
Fort Collins, CO
Joined Aug 2004
323 Posts
MAKING FORMERS using random kitchen objects

Got some more done on the build - working on the landing gear mounting now - it has to be very tough and durable, yet yield in the right way if and when a hard landing comes along and tries to rip the gear off...

this required extra formers, I decided, so a great time to illustrate how I discovered making formers on this build. I have not used this technique before (and for all I know many people are already doing this) but it is working out wonderfully. An easy way to give your profile plane some depth

Enjoy!
--Mark
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Old Oct 22, 2009, 10:17 AM
Registered User
North Kent, England UK
Joined Jan 2005
301 Posts
Now I know what to do with that bag of depron offcuts I've been saving.

Excellent job.
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Old Oct 23, 2009, 08:51 AM
'Cobra Fan - P-39 & P-63
Rengine's Avatar
Fort Collins, CO
Joined Aug 2004
323 Posts
A bit more done...

H E L L J U G - update


...Got the servos installed for rudder & elevator, almost finished the landing gear mounting...I'm trying to create something that will break nicely if a harsh landing ever occurs...not like that happens - but I've got an idea to try using bamboo skewers...did initial balance testing - looks good mounting the battery just above the leading edge of the wing right behind that former...

...that's about it for today
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Old Oct 26, 2009, 09:31 AM
'Cobra Fan - P-39 & P-63
Rengine's Avatar
Fort Collins, CO
Joined Aug 2004
323 Posts
H E L L B E A R - (new name-sounds cooler than "helljug")

H E L L - B E A R

Got lots done over the weekend, all control surfaces rigged and running and covering/outer shell installation about 80% done. Still figuring out the wing securing method - not sure on that yet - but I know I can still maiden it with something temporary while I decide.

Weight is going up since I'm gluing the outer skins on (my last build like this, the "Corbra" - i used packing tape on the outer skins). So maybe 3.8 lbs for this build, perhaps even 4lbs - but that's just a guess at this point.

Also decided to program flaperons in the mix since after I powered up everything the aileron servos were not quite centered properly. As a result the ailerons are both in a slight UP position right now (good for adding lift to this very flat wing, eh?

Even at 4lbs it's still going to be quick as a wink Maiden next weekend for sure - if not before - but the weather here in Fort Collins, Colorado is supposed to be cold, windy, snowy for the next few days...

Have a good day!
Mark
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Last edited by Rengine; Oct 26, 2009 at 10:57 AM.
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Old Nov 01, 2009, 12:16 PM
'Cobra Fan - P-39 & P-63
Rengine's Avatar
Fort Collins, CO
Joined Aug 2004
323 Posts
MAIDEN FLIGHT Video

MAIDEN FLIGHT Video

Everything went well - I think my flaperons were a tad bit in the up position (if you look close on the take off you can see what i mean) so it was flying in a tail low attitude...I was wondering why until I saw my hat-cam video in slo-motion. i think that is why...but will determine a lot more as I get more flights on her and play with the flaperons.

The great news is the super thin wings worked great - the do flex a bit, and that's just fine. see the landing slo-mo to watch 'em bend. The power-off glide is awesome - floats in nicely and doesn't drop a wing at stall.

So the wings are definately strong enough for the approx 68 oz weight. The hacker 30 and 14x7 prop pull plenty hard on 4s1p 2200 mah pack - and I've no doubt it will carry a 2nd lipo pack giving me 4400 mah of fun foam flying time.

I ended up adding two additional carbon fiber arrow shafts to the wings - and completely packing taped the top & bottom of the wings. I think without this additional support I'd proabably snap off one of the wings...

Gotta figure out how to finish the canopy (maybe built up a F4F type - or perhaps a more Edge 540 type...) and do some kind of painting or decorating. It looks a lot like a submarine from the side now...and with no paint orientation can be tough when far away.

will post a few more pics too when I get a minute.

Enjoy!
Mark


http://www.youtube.com/watch?v=KLzAWg-cm9A
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Last edited by Rengine; Nov 01, 2009 at 12:24 PM.
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Old Nov 01, 2009, 04:24 PM
did a reversed Immelman..once.
SKYPILEIT's Avatar
Novi, Michigan
Joined Nov 2002
2,249 Posts
the Hell Bear.!

Very interesting project Mark & I'm amazed at your building skills...& you did it in only 10-11 days.?That's real good...(it would have taken me a couple months)

Please..share the next few flight vids with us,I'd like to see it with the larger packs & Cg forward a bit.Can't wait to see it all painted up with military insigs.

I can see alot of snow in Ft.Collins already..I guess that means we'll be getting it in another few weeks.Lookin' at the next 6 months of Mich. winter.

Oh well..
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Old Nov 02, 2009, 12:24 PM
'Cobra Fan - P-39 & P-63
Rengine's Avatar
Fort Collins, CO
Joined Aug 2004
323 Posts
Highlights video footage from 11/2 - Touch N Go

Here's some more footage - this thing flys GREAT !!!!

I'm very pleased with the outcome...still haven't flown with 2 - lipo packs yet. The flaperons are cool - but it sure doesn't need them to slow down...most of these landings - in fact all but one - were done with out any flaps down....

P L E N T Y of power (not enough to hover for more than 2-3 seconds though) and I had a couple of hard landings with no damage - whew! the wings will take a hit and flex - and come back for more.


SKYPILEIT - thanks for the nice comments, it was a quick build - and I had to focus to get it done. I normally take 2 months or more... But that's what Michigan winters are for, right? Building time!

thanks,
Mark

HELLBEAR RC foamie airplane warbird 3d type (5 min 23 sec)
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Last edited by Rengine; Nov 02, 2009 at 01:34 PM.
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