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Old Jan 24, 2011, 04:36 PM
ooooh yeah
Frenche's Avatar
Ballarat, Victoria, Australia
Joined May 2004
1,600 Posts
Build Log
Supermarine Attacker for 90mm from Chris Golds plans

Ok all, since my F-111 is on hold until I can afford the fans/motors so in the meantime whilst I have the building bug I thought I would make a start on this. I've had a copy of Chris Golds Supermarine Attacker plans for a minifan 480 for years but always wanted it a little bigger so I had the plans blown up fit a 90mm fan. This makes the length and wingspan around 47" or 120cm. I plan to make the wing removable for transport and to add servoless retracts. Construction will be 6mm depron formers with a 3mm skin, most likely strip planked since the fuse is essentially circles of varying sizes from the intakes back.

After looking over the plans and realizing that the copy place didn't exactly do a brilliant job of copying them (since the original plans were folded, when they ran it through their scanner, some of the creases folded over, see pics) but with a little patience they will work. Also the stock fan position worries me, I'm no expert by any means but it looks too far forward. Of course since it has a rather short fuse in front of the cg maybe I need the fan that far forward because you can't slide the batteries forward to balance it, see pics. I propose to move it back to the next former, anybody see anything right/wrong with this? It wont be ridiculously powered, only around 1500-1600watts but that should be more than enough for scale performance, the full size wasn't exactly a rocket ship.
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Old Jan 24, 2011, 08:14 PM
EDF rules... :)
AirX's Avatar
Joined Nov 1999
13,635 Posts
Hi Frenche,

On my designs the fan ended up at the trailing edge of the wing.
I use a CG calculator to gather the data to find out where parts need to be to get balance in the right place. I wrote an excel spreadsheet after seeing one a long time ago. I might put a copy in my blog when I get time to seperate it from a workbook.

Eric B.
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Old Jan 24, 2011, 09:51 PM
ooooh yeah
Frenche's Avatar
Ballarat, Victoria, Australia
Joined May 2004
1,600 Posts
Thanks Eric, after a bit more thinking I think I'll leave the fan in the standard spot. This way since I have a removable wing I can also access the fan at the same time, no need for a separate fan hatch.
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Old Jan 25, 2011, 01:35 AM
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Canada, ON, Mississauga
Joined Feb 2006
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Super Marines Attacker!!, WOW one of my to do projects at some point of my modelling carrier!, Pakstan AF was only other air force who had whole fleet of there early era jets. Initially they had teething problems with them but then they got good handle on these planes. I built a small 1/72 scale Attacker kit from NOVO models kits back in the days but always thought about RC version of this early jet. I'll be watching how you do ur build and i wonder if plans from Chris Gold are still available of not....hmmmm
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Old Jan 25, 2011, 03:00 AM
smithy
jumpy's Avatar
Cornwall, UK
Joined Dec 2004
524 Posts
Couldn't find the Attacker but lots of Chriss Golds plans here.

http://shop.traplet.com/browse.aspx?c=51
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Old Jan 25, 2011, 03:26 AM
ooooh yeah
Frenche's Avatar
Ballarat, Victoria, Australia
Joined May 2004
1,600 Posts
Plans available here

http://www.modelactivitypress.com/am...le%20Electrics

Wanted to get some more work done but "she who must be obeyed" is coming over . Basically each fuse half will be built over the plan minus the planking then joined together for planking. I have the keel for 1 side pinned down and all the depron formers cut (I will attach the 2 ply ones at each end of the wing saddle once the halves are joined). I've had to add a former just behind the fan between formers 'I' and 'J' as this is where the wing ends, right in the middle of 2 formers making it tricky to bolt the wing on. Cutting the rear formers was easy, put my hobby knife in my compass spin it a few times and hey presto, perfectly round formers
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Old Jan 26, 2011, 06:00 PM
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SDF
Joined Sep 2002
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Funny. I have the same plans and pulled them out the other day for a look. Does anyone have the construction article that went with it? I've thought about blowing them up for a 90mm as well. Is 47" what gave you the right outlet size or did you just settle on that size?
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Old Jan 26, 2011, 06:37 PM
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St.Catharines, Ontario
Joined Jan 2009
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very cool project Frenche. subscribed.

Rich
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Old Jan 26, 2011, 09:08 PM
Fast Jets for Fast times
Lmeano_from_MO's Avatar
St. Peters MO.
Joined Nov 2007
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This does look like a good one. You will like the dapron bulkheads, you can make the parts fast.
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Old Jan 26, 2011, 09:28 PM
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St.Catharines, Ontario
Joined Jan 2009
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yeah XPS foam is great for that, no matter what the brand. I've cut all the ribs for the 757 already and they need no sanding or anything. just glue it all together. certainly an easy way to build a plane very fast.
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Old Jan 27, 2011, 12:21 AM
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Frenche's Avatar
Ballarat, Victoria, Australia
Joined May 2004
1,600 Posts
FOShowNoClass, to be honest I didn't think of the exhaust diameter, I just had them enlarged by 90/70=1.28, in fact I might have gone to 1.33 so it was an easy 33% upsize. Also I'm positive I have the magazine article somewhere but for the life of me I can't find it, have been looking for ages for just this reason.

Lmeano, yep fast build for sure, spent a leisurely hour in front of the tv cutting out the bulkheads and another 15min to glue 1 side to the keel.

No work was done yesterday as it was Australia Day and I spent the afternoon downing a few quiet ales (ok a few too many, at one point I'm pretty sure I was playing bowling using my empties as pins, and I know I drank more after that ) whilst having a bbq before going and watching the fireworks with 30,000 other people. Not as good a time as my brother had though, we dropped him off at 9pm at a bar and as of 7am this morning when I went to work he STILL wasn't home, apparently dad had to go and fetch him at about 2pm this arvo and as I type he is still passed out in his room, and the bathroom smells of disinfectant, young people today can't hold their beer

Ok pics of the progress, step 1 was to CAREFULLY cut the fuse plan and tape back together to get rid of the 'crease' created when copying. Next 1 keel was pinned to the board, which is only JUST big enough to fit the fuse at a slight angle. Instead of tracing the keel and cutting it, I experimented with using a flat strip that I just bent around using pins to hold it in place, worked very well and is material 'efficient' . The keel is a 10mm wide strip of 3mm depron, tapering in the last few bulkheads to about a 3x3 square.
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Old Jan 27, 2011, 06:42 PM
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St.Catharines, Ontario
Joined Jan 2009
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don't worry about the actual exhaust size, as long as it's at least 100% of the Fan's FSA. you can always put a thrust tube inside the exhaust, that has a diameter based on about 85% of your fan's FSA.
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Old Jan 28, 2011, 04:26 AM
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Ballarat, Victoria, Australia
Joined May 2004
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Rich, that's why I've left the last bulkhead solid, that way I can make a thrust tube to whatever diameter I want

Ok a bit more progress, 2nd side bulkheads were glued to its keel and both lots joined together, it's starting to loo like an Attacker . I also attached the stringers that sit under the skin to try and keep the keels straight and the bulkheads square but after I glued both sides together I noticed their is a little bit of warping , nothing too major, a little careful cutting and re-gluing and/or some heating and bending will put it right . Right now it is VERY fragile, it takes very little pressure bend or twist the entire structure. I'm thinking about making something to hold it whilst I plank it so I don't induce warp. Since the holes in the bulkheads are a bit oversize (fan location has a diameter of about 96mm) I was thinking about making the thrust tube out of 3mm rolled depron. This way I can add a lot of strength to the most fragile (rear) part of the fuse at once with hopefully no warping
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Old Jan 28, 2011, 09:36 AM
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SDF
Joined Sep 2002
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Looking good! What structure does the wing tie into? The plans just make it look like its just glued in with the wing sheeting and fuse planking. Does the wing saddle glue to any of the formers?

Will
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Old Jan 28, 2011, 06:52 PM
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Frenche's Avatar
Ballarat, Victoria, Australia
Joined May 2004
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Will, that's why I've been looking for the build article because I can't remember how it was done on the smaller version. Of course since I'm using a removable wing some engineering needs to be done to accommodate this. The front anchor point should be pretty easy, just need to notch the wing leading edge to fit around bulkhead "G" which will have a 3mm ply doubler with 2 holes in it for locating dowels glued in the wings. The rear is a bit harder since the wing kinda ends in the middle of no mans land between bulkheads "I" and "J", I'll have to add another 3mm ply bulkhead here with ply tab sticking forward so I can put 2 bolts through the wing to secure it. Depending on how strong the fuse is I might use bolts as well as the dowels at the font, the last thing I want is the fuse to flex allowing the dowels to slide out, I've seen that happen before, wasn't pretty.

Now onto another problem, the tail wheel. Since the jet is a tail dragger I'm going to need rudder and tail wheel control. The full size has a retractable tail wheel (well tail wheels, it had 2) but there just isn't enough room back there for a retractable one at this scale so I've settled for a 'fixed' one, once in the air you wont notice it. I was hoping that the rudder hinge point and the tail wheel would line up so I could just run a torque rod from the rudder, down through the duct to the tail wheel. Unfortunately they don't line up , not even close, they are out by over an inch. Worst case scenario (but the easiest to make) is I use 2 servos but I don't really want to do that, I have a few ideas kicking around but if anybody has some please feel free to post them
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