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HobbyKing 1800mm (71inch) Foamy Decathlon night flyer

Started by Paul Lange, August 22, 2016, 10:49:17 am

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Paul Lange

August 22, 2016, 10:49:17 am Last Edit: August 22, 2016, 11:38:24 am by Paul Lange
Picked up this large HobbyKing foamy 1800mm (71inch) Decathlon Friday night used from an on line seller.  Got it back home and deployed the stock Kv600 motor with a large flat bell type 820Kv Donkey motor and stepped up the stock plastic 14x7 prop to a nice XOAR PJN 14x8 wood prop for electric.  Beefed up the 40amp BESC to an 80amp BESC (I had to solder in a very long battery lead since the BESC is mounted just behind the motor firewall for proper COG help - while the receiver and battery are at least 18inches back and needed a little more for easy fingering therefore a full 2ft is what I ended up with.  This is not optimal but for a slow flier it's OK with me)...also needed a throttle wire lead extender for the receiver at mid section........and proceeded to go through the rest of the plane.

The previous owner did NOT know about the pinch bolts in the wing for the wing spars.....he is lucky to have flown the plan without using them and having anything left to sell.  Every one of the wing strut nut and bolts were extremely loose causing wing warp.  The tail feather wire stings were loose and the rudder servo was very weak and notchy.....so I replaced it with a metal gear 17g digital servo.   I now wonder how the previous owner flew this bird at all!!!!

The battery hatch for this large bird is on the bottom of the fuselage....which is a pain to work with....I cut the top cabin window and installed magnets for easy removal and re-deployment for access to the top cabin floor access and battery tray (battery strap is now pulled up top easy greasy).

The foam wheel pants were a mess...so I beefed them up with popsicle sticks and epoxy and re-drilled mounting holes on the landing gear struts.  The landing gear struts are the weakest, soft, pliable aluminum I have ever come across - the will bend unless you land perfectly like a butterfly with sore feet!!

I reamed out a GreatPlanes 2.5inch spinner with aluminum spinner back-plate and painted the nose cone red.

The maiden proved the 90mm COG but boy it was very pitch sensitive on elevator....I guess this is par for a large top wing Decathlon.....subsequent flights proved much better limiting the travel via transmitter down to 80% and 45% expo on the sticks.

Flight battery for now is an Admiral 4s 40c 4000mAh LiPo landing at 3.83v per cell at around 6minutes.....right on cue but only if throttle is kept low at or near 50%.

The airframe is no hot dog.....NOT true to the Decathlon fame.....this big bird is a slow flyer docile trainer - huge loops and seems to enjoy inverted at the top of the loop....hammer heads are majestic and very predictable.  After four flights and perfect landings.....seemed like a good candidate as I hoped as a night fler..........time for the LED strips.

I had to make up four disconnects for the LED strip as the cowling needs a disconnect, the bottom hatch needs a disconnect and the two wings require disconnect.  Figured I'd like to have the bottom fuselage all white coming all the way up the front cowling and placing a couple of short strips in the cowling cooling vents with one facing down and the other forward - Green and Red on the bottom wings from fuselage all the way down the wings then jumping a long strip perpendicular to the wing out on the wing tip from leading edge all the way back to the trailing edge.  I chose a yellow strip on the leading edge of the stabilizer powered by the end of the bottom fuselage strip.  A 3s 2c 350mAh LiPo powers the LED's and piggybacks on top of the main 4s LiPo.  I made a long lead for the LED 3s LiPo to ensure I had enough wire to manage the battery.  This is a large bird so it has lots of room in the cabin.

This bird is really nice to see in the air all lit up like Christmas.......easy to see and the LED configuration I made up is very good.....the Yellow strip on the forward edge of the stabilizer really is visible (glad I chose a different color) as it helps validate the airframes orientation.  The bottom fuselage single strand white lights help determine the airframes heading and provide lots of light as it nears the ground.  The bottom sides wing strips are excellent in the air....the top side wing tip lights are well seen in the turns....the only time the airframe gets really dark is when it's flying directly away from the pilot - however flying relatively close the rest of the birds LED package is plainly seen.

It's a very relaxing and enjoyable trainer....quiet and slow.....but the  big torky motor and weak landing gear do provide a little bit of stress on the airframe and pilot during take off and landing ....it is possible to execute perfect take off and landing respecting both of those issues in mind.

I don't have any video yet as my Mobius video camera battery may be failing......so here are some stills of last evenings LED flights.....three good sun down cruises .....it's a very pleasing sight to see

Paul H Lange
Best Regards - Paul H Lange

Jimmy Stanford

That looks good Paul, I may have to do a night flier!!
I swear I was in front of that tree :-)

Paul Lange

Greetings comrade!!

Ya get a big slow flyer.....something nice and steady....easy to take off and land.....adding the LED's is really fun and pretty straight forward.  You will need to solder wires to the strips but the LED strips make that part very simple.  They are self adhesive peel back sticky...no fuss no muss and are blinding bright at night!!

The LED strips are rated for 11.1v 3s battery power....so I use the balance plug of a 350mAh 3s LiPo (mating to a male pin 3s LiPo connector) to power the LED's.  The little 3s LiPo piggybacks on top of the 4s 40c 4000mAh LiPo flight battery.

This thing is awesome in flight......I have not flown it at total dark yet....need more stick time for that....however in the late twilight as the sun has just set down into the horizon you can still see the runway.  I get about three flights in before it's totally black night and the hogs, skunks, coyotes come out to play out there.  There is a growing crew of night flyers now.....flying LED power gliders......it's really pretty to see them all up there.

I put some more LED's on the wheel pants last night......hopefully can get a video of a flight very soon.

Best Regards,

Best Regards - Paul H Lange

Paul Lange

August 24, 2016, 01:37:50 pm #3 Last Edit: August 24, 2016, 01:42:36 pm by Paul Lange
Deployed additional LED's to the wheel pants.....applied two coats of Minwax Polycrylic Gloss Finish, installed a Hobby Eagle A3 stabilizer, repaired the slop in both the Rudder and Elevator control horns....also found the top hinge of the Rudder was broken, tightened up the tail feather box strings (were merely on for looks with no tension whatsoever),

Now I "might" have found why this airframe needed trimming on each flight so far.......

Anyway the Minwax Polycrylic Gloss finish makes this airframe pop.....really a nice effect.

Paul H Lange
Best Regards - Paul H Lange

Bill Bradford

That is impressive, Paul. When I try night flying I know who to contact.