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Old May 05, 2015, 03:57 AM
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10S powered Top Gun, "L-39" Albatross, Crash aftermath.

LET-39, the latest project to ad to my EDF collection. One of the most popular trainer
jet design, but 5-6 cell recommended power set up for this 90mm foamy wouldnít suit
me so I have decided to hot it up to 10S to make it little heavier so it can handle
windy beach conditions much easier. After close inspection, the wing and mainly
fuselage needs lot of strengthening to handle 4.5kg (10lb) AUW I like to achieve as
completed model. The big plus in this model is lot of space under the canopy for large
set of batteries but the biggest weakness is fuse joint around the intakes which will
need some serious beefing up next. Starting with the main wing two 50cm long CF
spars were aligned and epoxied in, while joining the two parts. Some additional CF
rods are fitted in some crucial areas for the peace of mind. All control surfaces are
being removed and proper hinges fitted with more powerful metal gear servos
installed. Normally I donít install RUDDER control in these foamies, having enough
authority to turn the model with AIL/EL. function only, but in this case the extra aft
weight will be useful to balance my model. At later stage I make decision if electric
or small set of air retracts will be fitted and which 10S power set up I use out of three
I have to choose from Iím currently testing on the stand. Iím not after the speed in this
build but mainly reliability and nice stable scale flying off the beaches at low tide in
windy conditions which is becoming norm these days while we are going through this
miserable wet laínino. Stay tuned.
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Last edited by jofro; Jul 06, 2016 at 01:38 AM. Reason: flying
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Old May 05, 2015, 07:57 AM
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What retracts were you planning to use? The mounts will need attention for sure.
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Old May 06, 2015, 04:06 AM
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New power unit formers fitted with few more carbon fibre rods in some high stress
area. While fitting larger ESC some more surgery with the new base is made up. To
give me some idea for the battery placement I temporarily joined the whole frame
working out the balance, also giving me an idea about the AUW, which will be
lighter then expected even with larger 5Ah pack so I have enough margin for using
heavier duty landing gear. While using light spackle putty I started on preparation of
internal duct before sanding, sealing off and final coat for perfectly smooth finish.
Few more pix.
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Old May 06, 2015, 04:22 AM
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Originally Posted by 4stripes View Post
What retracts were you planning to use? The mounts will need attention for sure.
I'm still shopping for some heavy duty set of E/retracts, 7kg range. You are correct, any of these foamies needs lot of attention especially if you build them heavier. I have been using on most models of this size Air retracts as I have pretty bad experience with E powered ones in 70mm EDFs off the grass.
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Old May 07, 2015, 04:28 AM
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First test run after programming ESC and more work done to the front fuse to accommodate 10 cell lipos.
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Old May 08, 2015, 03:25 AM
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Shoving in more carbon fibre, there will be about 7meters of it inside the foam, new battery base also strengthens my frame.
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Old May 10, 2015, 02:30 AM
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Mixing white/black/ochre and touch of magenta I got perfect mix to repaint the whole frame after some putty job.
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Old May 12, 2015, 03:24 AM
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While joining the fuse halves more carbon fibre is stuffed in.
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Old May 14, 2015, 03:24 AM
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My new colour scheme and start of fitting the gear.
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Old May 15, 2015, 03:47 AM
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Some imagination needed to accommodate the larger nose gear with more substantial former fitted in.
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Old May 16, 2015, 03:31 AM
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Making use of my hobby lathe adapting the stock oleos to fit larger retracts. Doubling the oleo plate will handle the extra model weight.
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Old May 17, 2015, 03:26 AM
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Leaving 10cm of slack for both El. leads just in case, before final plain assembly and metal bonding of doubler plates on oleos ready to be installed.
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Old May 18, 2015, 02:50 AM
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Slowly taking up the shape, I managed to hook up all controls today beside few flights between few showers.
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Old May 20, 2015, 03:39 AM
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More carbon fibre stuffed in for crucial areas before final assembly.
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Old May 21, 2015, 03:14 AM
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Heavy duty 8G batt. leads soldered to the ESC.
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