Hobby King 90mm L-39 Hobby top gun Fly Fly

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Just got mine today in the mail! Nice model and great value. One note of caution, Take the fan off and reassemble the motor/fan assembly. I found the spinner screw loose and the fan mounting nut loose as well. The set screws holding the 5mm shaft adapter were loose as well! An accident waiting to happen. I removed the two screws holding the motor on and replaced them with some that had a larger head to spread the load onto the plastic (using locktite). I also wrapped the motor with tape until it fit snug into the shroud to make it more secure. With only two mounting screws you must make every effort to stop the motor from moving or the plastic will crack and destroy the entire fan. I tested the balance and the fan was fine. 
Cheers

PS After testing the fan on 6S I was dissapointed with its performance of only 1100watts. 1650Kv is just too slow. Also found the shroud cracking after only a few short runs...
I'll be replacing the whole assembly to get decent power.

Edited by 4stripes - 21/Jan/2011 at 9:47am

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4stripes Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum (CA) USERID: 421518 HobbyKing Constituent Joined: 26/Sep/2010 Online Status: Offline Posts: 154	Quote Reply Topic: Hobby King 90mm L-39 Hobby top gun Fly Fly Posted: 19/Jan/2011 at 8:45am
	Just got mine today in the mail! Nice model and great value. One note of caution, Take the fan off and reassemble the motor/fan assembly. I found the spinner screw loose and the fan mounting nut loose as well. The set screws holding the 5mm shaft adapter were loose as well! An accident waiting to happen. I removed the two screws holding the motor on and replaced them with some that had a larger head to spread the load onto the plastic (using locktite). I also wrapped the motor with tape until it fit snug into the shroud to make it more secure. With only two mounting screws you must make every effort to stop the motor from moving or the plastic will crack and destroy the entire fan. I tested the balance and the fan was fine. Cheers PS After testing the fan on 6S I was dissapointed with its performance of only 1100watts. 1650Kv is just too slow. Also found the shroud cracking after only a few short runs... I'll be replacing the whole assembly to get decent power. Edited by 4stripes - 21/Jan/2011 at 9:47am

vasy1 Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum (US) USERID: 15488 HobbyKing aficionado Joined: 10/May/2009 Location: Canada Online Status: Offline Posts: 1064	Quote Reply Posted: 21/Jan/2011 at 11:26am
	Mine is on the way. Will take your advice. I have another 90mm jet with 1680KV motor and run it on 8s for 2600 watts, that thing moves, sound like this setup will not take it :) Will stick to 6s and see how it goes. I'm surprised that shroud is cracking, probably unbalanced rotor. Edited by vasy1 - 21/Jan/2011 at 11:32am

4stripes Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum (CA) USERID: 421518 HobbyKing Constituent Joined: 26/Sep/2010 Online Status: Offline Posts: 154	Quote Reply Posted: 22/Jan/2011 at 6:56am
	I tested a few rotors (the older FLY FLY that is same as heoye and the Wemotec midi clone) and were not prefectly balanced. None were badly out but the brittle shroud couldn't take it. The newer FLY FLY fan that came with the L39 is similar to the wemo but has a smaller hub and thicker construction. The older FLY FLY/heoye was way too much load for the supplied motor and was rapidly overheating with only half throttle. The best balance of power and efficiency is the wemotec midifan type (clones). I just don't like their shrouds as they limit you to a 36mm motor. I tried the heoye 90mm fan and shroud with a Turnigy Typhoon 500H 1800kv motor to possibly replace the L39 fan but the fan also overtaxes the motor (over 2000watts 90A on 6S). I put on a wemotec fan and all was good! The only problem is the fan is slightly too small a diameter (for the heoye shroud). I fixed that by cutting the end off of the fly fly shroud, cut the cylinder and sanded the ends just enough to fit inside the heoye shroud! Crazy glued it in and it works like a charm. Motor settles down to about 1400watts for most of the run (at 65A). Exact same numbers as the FREEWING 90mm motor and fan.

4stripes Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum (CA) USERID: 421518 HobbyKing Constituent Joined: 26/Sep/2010 Online Status: Offline Posts: 154	Quote Reply Posted: 12/Mar/2011 at 5:38am
	The Hobby Topgun L-39 is a very nice 90mm foamy. My dad deserves all the credit for details and cockpit and it is our best EDF yet. The two cockpits require extra effort as they are too large to ignore. The upgrade from parkflyerplastics required heavy modifications to make more scale but the clear canopy is a much better outline than the stock one (The exterior frames are in a better position). The wings are reinforced with carbon fiber and alloy arrow shafts. The stock landing gear legs have been modified to make them shorter. I've used some inexpensive FLYFLY clone air retracts from HK and the servos are HXT900. Flaps were added to improve T/O rotation and reduce landing rollout (worked well on my F-86). The final weight with 6S 5000mah 45-90C Nano-tech battery is 3.08kg (about the same as my F-86 and F-16). The fan is a hodge podge of parts. Freewing fan, Haoye shroud lined with plastic to reduce inside diameter and Turnigy Typhoon 500H 1800kv motor. The 38mm motor diameter forced me to use the Haoye shroud but I didn't like the fan as it drew way too many AMPS. The Freewing fan is a smaller diameter so the shroud inside diameter had to be filled to reduce the clearance. Hardly worth the effort as a stock Freewing motor/fan will produce similar thrust. We chose the DDR (East German) markings as they used a similar camo scheme that the plane comes with. All large markings and cockpit instruments are photographs printed on photo paper. The smaller markings were hand painted. We also added a rudder (as we did on our F-86). All things considered this is a better product than the F-86. The biggest improvement is the landing gear struts are beefier and the flying surfaces are also more solid. Can't wait to fly it! Cheers

speedy72vega Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum (US) USERID: 202846 Forum Admin Joined: 29/Apr/2009 Location: Colorado, USA Online Status: Offline Posts: 2063	Quote Reply Posted: 12/Mar/2011 at 9:19am
	Suberb detail!!!! VERY nice job . I am about to install the 1850kV Warhead Outrunner in mine. I'm going to leave it 6S for now just to see if there's a worthwhile improvement. The FlyFly Retracts just came in stock, so I ordered 2 sets. That should help a bit too. I love this bird, the flight characteristics are quite good. I think i'm going to do the Rudder mod too.
	Uncontrolled contact with terrain is a bad thing.

4stripes Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum (CA) USERID: 421518 HobbyKing Constituent Joined: 26/Sep/2010 Online Status: Offline Posts: 154	Quote Reply Posted: 12/Mar/2011 at 9:37am
	Let us know how that "warhead" motor works. 1850kv is a good number for 6S. I've tried the 1900kv motor used in the Change sun fan/motor combos (in a freewing fan) but I don't know the thrust yet (will go in a Mig15 soon). How did the recommended CG work out on this bird? I plan to fly mine later this month and don't want any surprises! I hope you ordered the air type FLYFLY retracts... my electric FLYFLY have been nothing but a headache. The brass tube that the drive screw operates tends to strip with any resistance to the gear movement. I was able to get replacement brass parts direct from the factory but swapping them out isn't my idea of fun (that's why I switched to the cheap air type).

speedy72vega Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum (US) USERID: 202846 Forum Admin Joined: 29/Apr/2009 Location: Colorado, USA Online Status: Offline Posts: 2063	Quote Reply Posted: 12/Mar/2011 at 2:22pm
	I got the electric ones, I like the way the steering is done, no pull-pull wires to mess with. One of the guys in my club has the same plane with the electric retracts, and his seem to work ok so far. I did some test runs with the Warhead motor, I got 1400 Watts with a freshly charged battery, was just barely over 900 Watts with the stock setup. Bad thing is, there's no provisions for any cooling air to get to the motor. The blade pretty much covers the whole front of the motor, and where it mounts to the duct there's plastic all the way around the outrunner housing. It got pretty hot during static test runs. I'm going to test fly it tomorrow if the wind isn't too bad, i'll let you know how it goes.
	Uncontrolled contact with terrain is a bad thing.

speedy72vega Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum (US) USERID: 202846 Forum Admin Joined: 29/Apr/2009 Location: Colorado, USA Online Status: Offline Posts: 2063	Quote Reply Posted: 13/Mar/2011 at 2:00pm
	Well, flew the L-39 today with the Warhead 1850kV motor. Very nice improvement over stock! Bad thingis, I couldn't get the shaft adapter off of the stock motor, and HK is out of stock on them. I ended up ordering a fan and duct assy from another vendor, those are out of stock here too. Turns out, the duct is just a bit too big to fit the plane, I ended up having to use the original one. Next bad thing, the adapter was a bit too small for the original fan blade, I ended up having to use the new blade in the old duct. The new blade isn't the best quality, and it seems the hole is drilled just a bit off center. There is a bit of a vibration at very low throttle, but it smooths out at higher RPM. I went ahead and flew it, and it flew great. I got what I would approximate to about a 25% increase in performance. I will be getting my Retracts this coming week, that should improve performance a bit as well. As far as battery life, a 2 1/2 min flight uses about 75% of a 6S 5000Ma pack. I'm going to order 2 3300Ma 6S packs and run them in Parallel, that should give me another minute or so of flight time, and they should fit the battery compartment ok side by side.
	Uncontrolled contact with terrain is a bad thing.

4stripes Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum (CA) USERID: 421518 HobbyKing Constituent Joined: 26/Sep/2010 Online Status: Offline Posts: 154	Quote Reply Posted: 09/Apr/2011 at 12:00pm
	The 2 1/2 min burning 75% sounds very high. Suspect your vibration issue wasting power.... Managed to do three flights yesterday for the "maiden"! love its looks in the air. My cheater hole is completely covered with decent power. Cheers

4stripes Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum (CA) USERID: 421518 HobbyKing Constituent Joined: 26/Sep/2010 Online Status: Offline Posts: 154	Quote Reply Posted: 16/Apr/2011 at 9:03pm
	Finally got the L-39 gear working properly so I've added some gear up shots. This aircraft handles strong crosswinds very well with its wide stance. Our legs are shortened 1" as the stock are too long. We also added brakes to help stop the fast landings when there is no head wind. The brakes are small levers pivoting just above each main wheel. They are actuated by a fishing line pulled by the flap servos when flaps UP is selected after landing. I always use flaps for takeoff and landing so the brakes are OFF until needed. They really slow the plane quickly so landings made very far down the runway can still be stopped in time before going off the end. There is extra wear on the tires so I'll use them judiciously.