Rock Breaker - RC Groups
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Mar 30, 2016, 08:04 AM
Rock Breaker
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Build Log

Rock Breaker

after flying foamies for some time I got my first carbon plane. A Gizlite, beautiful plane from a great builder. I love my Gizlite, it's speed and flight characteristics are awesome. The step up from a foamie well I don't want to go back to foamies. The only problem is I found I need 15knts to fly it and when I like to fly 4 afternoons a week it doesn't get in the air enough.
So I started experimenting with glass. A Weasel got rebuilt with a glass skin. A Bevolution got a glass nose. Next was cutting foam cores and male moulding a few experimental planes. these experiments have got me to a pint where I'm almost ready to be producing planes to my design brief.

Design Brief
A very tough planes that can handle lots of crashes.
Cheap. A bit more than a foamie and less than a carbon
Can slope soar in less than 10knts of breeze

Current prototypes meet the design brief except 10knts. At 630g I need 12-14knts, layup mods to save weight will get me under the 10knt breeze mark.
Enough for now
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Mar 30, 2016, 08:08 AM
Rock Breaker
gazasmith's Avatar
Rock Breaker prototype
Mar 30, 2016, 12:02 PM
Steve 0's Avatar
Nice, looks good. Howzit fly?

Anything hard on the LE under the glass? Like poplar, mulga, ironwood or thick weed whacker line?

My heavy duty foamies have 127 micron laminate ironed on with a D-Box overlap on the front.

I suck at glass/epoxy layup and bagging.
Mar 30, 2016, 07:18 PM
Registered User
what foil you using
Mar 31, 2016, 12:12 AM
Registered User
Alright thats an ambitious name, have you molded it? It would be nice to see some pictures of the making..
Mar 31, 2016, 03:54 AM
Rock Breaker
gazasmith's Avatar
Steve O
It flies good no tip stalls a course micro stall when your at low airspeed.
Leading edge is 600g glass wrapped nothing else. Fuse is 600g glass outer skin 200g glass inner with micro fibre sandwich.
Foil is PW51
I'll post about name tonight and more pics info as I get time.
Last edited by gazasmith; Mar 31, 2016 at 05:51 AM.
Mar 31, 2016, 04:20 AM
Did you mean PW51 ???
Mar 31, 2016, 05:51 AM
Rock Breaker
gazasmith's Avatar
Yep PW51
Mar 31, 2016, 05:55 AM
Nice - absolutely can't go wrong with that.

Best of luck with your project mate. Cheers, Steve.
Mar 31, 2016, 06:36 AM
Steve 0's Avatar
Sounds good. Wing span is what, 900 to a meter? And what does it compare to in flight, a fast Weasel? Faster? Or tame and floaty?
Mar 31, 2016, 06:49 AM
Rock Breaker
gazasmith's Avatar

The name

I was going to name this plane "Fusion" but found a plane and helicopter by that name.
The idea of fusion is all the different skills and experiences I'm putting into it.
About 35years ago I made my first foil a flat aluminium plate to replace the centre board I lost from my sailing boat. I advanced from there to hand shaped timber centre boards and rudders. I was a teenager with no computer so foil shapes were more guessing than the coords you can get today. Fibre glass and polyester resin entered dads shed so I started coating my timber boards.
My sailing boats has swinging planks that you pushed out the side of the boat and slid your arse on to balance the boat. Some constructions were solid timber until I saw a laminated plywood plank, so I made one, it's was so light and stiff.
Nowadays my sailing boats are bigger and more extreme so glass is out and carbon foam is the construction method.
The end of school came and I got a apprenticeship as a toolmaker. I learnt all about plastic injection moulding and press tools. I must be getting old it's 30years ago I first used a CNC machine. I'm still in the metal industry, my company specialises in matching. The moulds for the Rock Breaker were machined on 3 different CNC machines and the foam cores are cut on another. Modify a metal cutting machine to hot wire foam. Mould materials vary from aluminium steel and epoxy board.
A lot of sailing boats have only 1 set of sails, so when wind strengths change you need to adjust sail shapes etc to keep your boat fast. When it is gusty you need auto flex to go fast. These are other factors I'm trying to incorporate in the Rock Breaker.
Better add plane stuff, that includes scratch builds in corex and foam board. Never built a balsa plane they always look to fragile for me. Epp kits and modifing Epp kits to get something different from them.
That is my fusion of skills but a name already used so my plane was names less for a few weeks.

It was a warm afternoon, a general breeze from a good angle just perfect for a fly. Grab a few beers my nameless plane and stroll alone the shoreline to the water tower, settle into a shady spot take a few mouths of beer and prep my nameless plane. Alls good throw my plane and soar into the sky. Just float around for a bit testing the lift. Grab my beer and enjoy the flavour. Perfect beer and flying. Bees empty time to crank this baby up. Dive into the face and start some low level passes. Sweet turns are tight, energy retention is good, speed is good. Back and forwards my head follows the plane, then thud and no plane. Bugger a rock jumped up, stilly bloody rock. New beer plane must be totalled. Best pick it up unplug battery. Picked up my plane quick look and all parts are there, back to beer. Closer inspection and I notice the CG lead is missing. Bugger bugger back to rock but can't find it. Bugger bugger if I had the lead a bit of tape and back in the air. Beer is good.
Estimated speed 80kmh 630g plane dead square hit, plane stopped less than 1 mtr backwards.
There is still a debate on if the rock broke or was already broken.
This is why I now have a Rock Breaker.
Mar 31, 2016, 06:55 AM
Rock Breaker
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Rock damage

Damage mainly glue join between top and bottom fuse.
Mar 31, 2016, 07:11 AM
Rock Breaker
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Originally Posted by Steve 0
Sounds good. Wing span is what, 900 to a meter? And what does it compare to in flight, a fast Weasel? Faster? Or tame and floaty?
Wing span 1100
Speed faster than my windrider evolution,and bat haven't flown dream flite weasel for ages but faster than it. Slower than my Gizlite it's not the perfect designsTim does.
It will fly slow but as airspeed decreases stability goes with it. So far I find its best to let it run, carve the sky. Just be gentle on the stick don't over control it will still do sharp turns. Sunday wind forecast is 20knts hopefully angle is good so I can get a better idea how fast it will go.
Apr 02, 2016, 05:48 PM
Rock Breaker
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First wing mould

I'd never machined a wing mould before so going cheap sounded good.
I found a second hand peice of mdf board.
Program took some time as I don't have any cam ware. 300 coords is slow going, then checking them more time, test cuts and see there are errors. I looked at coords for ever until my dixlexic brain found the number in the wrong order. Finally or cords correct now how to manipulate them to cut a perfect foil. Add some mirrors loops offsets etc and I think I've got it.
25mm bullnose cutter to rough out.
Some error on the leading edge and bugger me got a mirror wrong bottom wing is backwards. The fix was to cut in half, 3 peice mould now.
Mdf had poor grain and soft so coated with gel coat.
8mm bullnose cutter and run a finish pass. Very slow was going to be 12 hrs machining. I found changing settings in the profile cycle speed up things a lot (this cycle calcs a curve between your coords)
Finally finished machining now sanding time.
First step Nikko pen or texter, scribble all over mould, this is great on the White, just sand until all texter gone.
Repeat process texter, sand with finer grade.
I found the fine ink would coat the bottom of scratches so was easy to see when you had removed all scratches from previous grade of sand paper.
Then came waxing it's almost as fun as sanding.
After a few days hard work some glass and foam in your mould, now waiting for it to qure bugger me I hate waiting.
After the forever wait opened up mould for my first Moulded wing. Close inspection some porosity some dry spots, I was happy with results.
I have machined a new wing mould now. Worked out my machine better so was heaps faster and lots more accurate.
Apr 02, 2016, 08:15 PM
Rock Breaker
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A plane in a box
This is the first Rock Breaker to be posted.
It's off to a DS pilot for testing. Should hopefully get a idea of how fast it is in a few weeks.
Slope time for me, I might get lucky and get a few DS laps in before crashing.

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