Scratchbuilt 110 inch Su-47 Berkut - RC Groups
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Feb 20, 2013, 11:59 AM
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Build Log

Scratchbuilt 110 inch Su-47 Berkut

Scrachbuilt Su-47 designed and built by johntjg. Well this build has been a dream of mine for about 10 years now with 2 smaller designs before it that have both prievously sucessfully flown.The first one was a twin 55mm edf that was all balsa at 3 pounds and 4 feet in length and the second. 6 feet in length and a single electric byron fan built from frankenstien construction. 3 different fiberglass fuselages to make one that has the similar look. I learned a lot from the 2 prototypes,
1. The canards are very effective, on the full scale in flight the canards are always negative deflection to the line of travel. Some down deflection on level flight .
If the canards are usedon the rc aircraft they have to be very minimal deflection or the plane will turn around on its self in a tight turn and fall like a brick.
2. The canard size has to be designed to loose lift before the wing so that the nose drops in a stall.
Stay tuned the airframe is already built and electronics are being installed and the finishing soon follows
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Feb 20, 2013, 12:24 PM
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This is about a weeks worth of work desiging the plans and cutting out all of the templates to hot wire the plug. I went to the local printing company Alegra and for 27 dollars I got my 3-views blown up to the size I wanted first and the copies I made from the cross sections of the 1/48scale model I had enlarged until they fit the three view. Then I went and bought the foam and started assembling the blanks to the size they needed to be to fill the spaces between the former templates.
Feb 20, 2013, 12:52 PM
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The progress is way further along than this pic .
The plane is built around two Ramtec fans with Little Screamers Extreme scream gold motors on 12s. Batteries are 4 60c 5800mah. I have always used this system before in other aircraft and they make over 18pounds of thrust a piece on 80% tailpipe outlet to the fan swept area . The intakes on the airframe are 100% to the FSA and fully ducted each fan is seperate from the other.
Feb 20, 2013, 01:13 PM
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A few more pics of the plane progress a few weeks ago. I am having trouple getting the pics from the phone to the computer.
After this plane is flown and all of the bugs are worked out I have every intention on molding it and making all of the surfaces composite and building another one for turbine power.
Right now the weight of the aircraft in the photos is 7 pounds and I am shooting for a 30 pound flying weight.
Feb 20, 2013, 11:34 PM
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Looks really cool mate, Cant wait for the flight footage!
Feb 21, 2013, 04:28 AM
argyris's Avatar
WOW!!!Great craftsmanship, congratulation!Great aircraft!
Feb 21, 2013, 05:10 AM
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Si Goodchild's Avatar
So, just to confirm, you're going to fly this as a giant foamy to start with, then use it as a plug to make a fibreglass machine? Cool!
Feb 21, 2013, 08:28 AM
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I was going to do a lost foam method. Melt away the foam after the fuselage is fiberglassed , but then I came to the determination of what if something goes wrong and it crashes and I would have a repair bill on my 2 Wren SS turbines. I decided to use this as the one test subject and later as the plug when I am satisfied with its habits in the air.
Feb 21, 2013, 09:21 AM
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I used wing tubes from a comp arf kangaroo that are 3/4" tubes and have a wall thickness of 1/8". I cut them in half and bult ribs in the wing foamcores to capture the tubes. I chose tubes over spar and channel material because of the ease of setting the incidence of the wingtips to the fuselage centerline would only require twisting the wing and setting the wing dowel rod plate into the fuselage in the desired location.
The wings have 3 degrees of washout built into the wing root with all forward swept designs the wingtips need to be at 0 with the fuselage .The wings have carbon fiber cloth sanwiched between the foam and wingskins to strengthen the wing and help protect it from any aerodynamic diversion that fsw often encounter.
Feb 21, 2013, 09:52 AM
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Forward fuselage finally attached to the rear fuselage with the aide of a laser in the foreground. This was kinda hard to explain to the wife why it was in the kitchen when she came home from work. The fuselage is tilted against the counter to keep the nose off of the ceiling.The ceiling is 8 feet/ 96 inches. The fuselage length at this point is 98 inches without the 12 inch stinger
Feb 21, 2013, 09:58 AM
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pic for the previous post that I made that didnt get uploaded.

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