Official Nexa 1630mm Junkers JU-52 Transport (Balsa ARF) Discussion Thread

[OV10]

My Tante Ju is kinda weird. It's like she yaws one way way with the tail wheel planted, then yaws the other way when the tailwheel comes up. The rudder and tail wheel seem to be aligned pretty closely and the Mains seem to have be tracking straight. After I get new motors in her, I'll try to figure out why she's so difficult to get running straight. I like a lot of rudder throw. Maybe, I just need to dial in some more expo, to keep from over-correcting.

Aunt Ju has a pretty significant sized rudder and is easily swayed about. I never had the issues your having and looked in the manual for what I had for throw and it was 15 degrees max.
Try tamping it back

[Oxotnik]

Me likes a lot of rudder. What can I say? I do agree that I need to dampen and/or reduce the rudder throw. it's just too dang touchy on the ground. Since I have differential thrust programmed, I can certainly get by with reduced rudder throw.

[Oxotnik]

I received my replacement motors yesterday (replacing Propdrive V2 2836-1000kv), since HK doesn't ever keep anything in stock. Actually, I had a lot of trouble finding 2836-class 4S motors anywhere. Even Motion doesn't have any in stock. I did finally find some Cobra 2808/30 1000kv motors (and I bought their last two). The Cobra 2808 motors are little fatter than the Propdrive 2836 motors, but are the same length. The Cobra motors cost a little less than twice the cost of the Propdrive 2836. I just finished running the Cobra and Propdrive motors through a Wattmeter test. The performance of the Cobra 2808 was very marginally better than the PropDrive 2836. And, they weigh within a couple grams of each other. They are virtually the same motor. The Cobra motor did sound a little better than the PropDrive motor, making me think that maybe it's a better motor. Really scientific, right? LOL

For those interested, here're the results of my side-by-side PropDrive V2 2836-1000kv and Cobra 2808-1000kv motors. The prop was a 9x6 (for Flightline FW-190D-9). The battery was an HRB 4S-5000 50C battery.



The published data for the Cobra 2808-1000kv and an APC 9x6 is
Vi: 14,8vdc
Imax: 17.39A
Power: 257.4 W
Thrust: 40 oz (1144g)

Here's the actual page, from which I pulled the published data above: https://rcdude.com/downloads/Cobra_2808-30_Specs.htm.

Anyway, I should have my Tante Ju back in the air this week. There's gonna be a warbird flyin at an RC Club about an hour north of me on July 25. I'm planning to take my Ju-52 and Do-335, to offset all of the Mustangs, Spits, and Corsairs that are bound to show up (in addition to the ones that I'll also be bringing... LOL)

[Oxotnik]

I'm surprised that I didn't calculate wing loading and power prior to my maiden. After reoutfitting my Ju with Cobra Outboard motors and new ESCs (so that all ESCs would be the same... due to my inflight motor failure, the right outboard and right ESC were trashed and thrown away), I did some weighing and measuring and ciphering, to get some performance specs.

The wing area wasn't provided in the manual; so, I did a little measuring.
Root chord: 12"
Tip chord: 4.25"
Span (one wing): 29.25"
Doing some easy geometry with some assumptions about the symmetry of the wing and the tip chord of the rounded wing tip, I got a total wing area of 570.4 in^2 or 4.0 ft^2

AUW: 6.8 lbs
Wing Area: 4.0^2
Wing Loading: 27.5 oz/ft^2
WCL: 13.8
Power (per motor): 320W
Power (3 engines): 960W
Specific Power: 141 W/lb

These numbers gel very well with how she flew on my maiden flight. Good power and faster-than-scale speed. Pretty easy to land, but had to be on the throttle. She'll sink pretty quickly in glide.

If anyone else measured their wing and got different numbers for wing area, I'd like to discuss it.

Chuck

[Oxotnik]

Oh, one other thing that I thought of...
After putting my Ju back together, I balanced her and she seemed a touch tail heavy, even with the 4S-5AH battery pushed all the way forward. I know that I balanced here prior to both fights and was comfortable with the balance point (although, I can't remember exactly where it was). She didn't seem tail heavy on the maiden flight, but did look tail heavy on the 2nd (crash) video during the initial climbout, although she did fly predictably once I got her up to speed and in level flight. So, I added 3/4 oz of weight to the Center Motor firewall. I think that that should keep her from dragging her tail during flight. She now balances right where the manual says that she should.

[TwistedGrin]

Gents - thanks for posting up your Parallel wiring looms....nice work.....like I need another model.....lawd hepp me

Thanks in Advance,
TwistedGrin

[Twowingtj]

OOS, who says German planes don't sell well?

[Oxotnik]

Last Wednesday or Thursday, after getting the replacement Cobra motors installed and the rudder/tailwheel throws and expo adjusted, I took my Tante Ju to the field after dinner, to see how the new setup worked. The Ju was still cranky on the ground (I'm now thinking that the problem is in the Main gear, as in one strut compresses much more easily than the other which is causing a pretty severe yaw as ground speed increases. Unfortunately, though, after getting my Tante Ju into the air, the control horn pulled out of the elevator, leaving me with no pitch control. Tante Ju slammed into the ground at ~45°, breaking the fuselage and mangling all three nacelles. I'm calling the airframe a total loss. I'll probably buy a replacement ARF. I REALLY want a Ju-52 in my Air Wing! If VQ (or Legend now) still has Splinter Camos, I'll get one of them. Otherwise, I'll get a Nexa silver Lufthansa model.

[Twowingtj]

That's a bummer Chuck!

I know how you feel when you have no pitch control. When the entire horizontal stab, elevator and rudder departed my 1/3 scale Fokker D-VIII and it went in, you get that sick feeling in your gut. Nothing like seeing several paychecks take a permenent dirt nap.

Good thing we have thick skins and just keep throwing more money at the hobby we all love .

[Oxotnik]

Thanks, Tony. In this hobby, there are flyers who have crashed planes and there are liars. LOL
I've always said that if you can't handle destroying an RC airplane, you're in the wrong hobby. I was pretty pissed when I smashed up my Bad Juju-52, but I got over it pretty quickly. My wife had be lying down taking a nap. I walked in the house with the pieces and tossed them on the bed, and said, 'Hey, I've got room to add another plane to my collection." My wife actually felt sorry for me and told me to go buy another plane. Gotta get sympathy whenever I can, LOL. So, yesterday, I picked a NIB 63" Hangar 9 Bf-109F-2 at a swap meet (for a crazy low price) and a few minutes ago, I bought a replacement Splinter Camo Ju-52 from VQ/Legend. And, I'll now have plenty of spare parts.

[Twowingtj]

Oxotnik And THAT's how it's done Chuck. Gotta love those wives that support our crazy addiction.

[Oxotnik]

Yeah, Tony, and you have a wife who's also addicted to model aviation. Life can't get any better than that!!!

[Twowingtj]

Lucky indeed Chuck. Looking forward to getting into the new house so we can get the building back on track. It's got a 14' x 30' build shop and another 15' x 15' for hangar storage. She really wants to get her Ju together.

[Oxotnik]

Tony, our house has a detached garage (no girls allowed!), I keep a bunch of planes stored in the attached garage. All of the kids have moved out; so, I have the upstairs to myself, other than one room that is the guest room and totally off limits to me. The nerve of her, making me stay out of one room!!! LOL

[Rmawer]

Evening all. Just when I thought I was ready to think about doing a maiden flight, I discovered the servos I chose were absolute crap. Yes, I know I screwed up by taking the cheap way out (HK 922’s); the damn things return to two different zero positions and I’m guessing 2 degrees difference. Flaps seem to return to exact positions so the plan is to replace the aileron, elevator, and rudder servos. For everyone who built this plane, did anyone use the recommended Freewing Servos? If so, what do you think of them?

[Rmawer]

Progress ? How or what did you do to get some cooling to the ESC's ? Found a Co. that makes connectors for just about any RC application. Very satisfied and saved me the aggravation of bad connections which I'm known for. Have all my parts now - ready to do some testing. 3 blade prop test to follow.

Finally got the plane finished but I need to change the aileron, elevator and rudder servos (see post on page 6). Cooling for the ESC’s, was thinking about drilling a few cooling holes in the center firewall but still looking at that. I did test the motor with a 4 cell and a 10x6 3-blade prop and it’s running at about 30 amps at full power. I like to fly scale so 45 amp ESC running at about 60-75 % power should keep the ESCs at a reasonable temp. Without external cooling. I did get an Rx with telemetry and can monitor esc temp on the first few flights.

right now, I need to replace the servos. This is too nice a plane to risk it with inferior servos.

[airotroy]

Evening all. Just when I thought I was ready to think about doing a maiden flight, I discovered the servos I chose were absolute crap. Yes, I know I screwed up by taking the cheap way out (HK 922’s); the damn things return to two different zero positions and I’m guessing 2 degrees difference. Flaps seem to return to exact positions so the plan is to replace the aileron, elevator, and rudder servos. For everyone who built this plane, did anyone use the recommended Freewing Servos? If so, what do you think of them?

I bought the Freewing 9G MD31093-300 servos. Hoping they work ok in the air. They all have centered ok on the table. I'm waiting some thin CA to finish the tail section. The rear wheel assembly came with a "horn" that appears to be too thick to insert into the rudder so I'll shave it down so its thinner and will fit into a slit in the rudder. Also I'v had a heck of a time with the gear assembly. The front and rear wire support channels werent cut deep of wide enough to accept the wires so I had to cut and dig them out. After doing that and using some of the "flat metal" hold down straps they sent me in place of missing nylons, I cant even get close to getting the Alum tube strut to fit in the front wire support after attaching the other end to the linkage device thats on the wing. Any advice would be appreciated. Thinking about painting the rudder and cowls yellow so I can see this thing easier in the air. Like others had to build a servo support for the rudder and elevator servos.

[Oxotnik]

10x6x3 props. Very interesting. You'll have plenty of power. Take good video. :-)

[airotroy]

I'm going with the 9x7x3's Havnt checked on the meter yet

[Rmawer]

I bought the Freewing 9G MD31093-300 servos. Hoping they work ok in the air. They all have centered ok on the table. I'm waiting some thin CA to finish the tail section. The rear wheel assembly came with a "horn" that appears to be too thick to insert into the rudder so I'll shave it down so its thinner and will fit into a slit in the rudder. Also I'v had a heck of a time with the gear assembly. The front and rear wire support channels werent cut deep of wide enough to accept the wires so I had to cut and dig them out. After doing that and using some of the "flat metal" hold down straps they sent me in place of missing nylons, I cant even get close to getting the Alum tube strut to fit in the front wire support after attaching the other end to the linkage device thats on the wing. Any advice would be appreciated. Thinking about painting the rudder and cowls yellow so I can see this thing easier in the air. Like others had to build a servo support for the rudder and elevator servos.

See if you can find these for the rudder attachment. They are called aileron horn hinges. I took one and cut it in half. Only requires an X-acto knife slit to install