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Dec 31, 2019, 04:18 AM
Everything's A Compromise
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Build Log

V-Tail Slim BF Explorer install.


I was hesitant to categorize this blog entry as a ďBuild LogĒ because when one buys a moldie, itís already built.
All thatís required is the installation of off the shelf items.

Iím logging the fit out of my V-Tail, Slim fuse, Explorer Big Flap F5J model because thereís either so little info to be found or itís not in a single location thatís easily identifiable.

Firstly, I wasnít expecting the extra long boom. About an extra 115mm longer than the Normal fuse.
Why would this matter? ... CG.
Iíd ordered the 75gram Leopard LC 250-30 4040kv motor with the 5:1 micro box from Reisenauer.
The last thing I want to have to do is add lead to the nose for CGing it.

I was also surprised that a Horizontal stab plus a vertical stab weighed the same as my 2 v-tails. Both configurations are approximately 60g.
It occurred to me that the Explorer may require 60g tails, regardless of configuration, for an achievable CG.
As some form of confirmation of that idea, my Vixen 2 V-tails are heavier than my F3J Vixen (winch launch) V-tails.
The only explanation I can think of is weight and balance.
Iím 99% certain that the v-tails are built to a minimum weight and could be lighter.
Last edited by Larrikin; Dec 31, 2019 at 06:03 AM.
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Dec 31, 2019, 04:41 AM
Everything's A Compromise
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Battery choice


Knowing that the BFs were ordered, I began to research what I wanted to put in them.
Yep, plural. Iíd ordered a Slim fuse ďLightĒ and a Normal fuse ďStandardĒ.
Interestingly, thereís just 21grams difference between the two models!
Somehow, me thinks, one of them is the wrong build weight.
Iíll add that both were ordered as double carbon.
Hindsight reveals that ... I have no idea why I ordered a double carbon ďLightĒ!
After all, a Light model isnít flown in conditions that warrant a double carbon build, right?
Yet it adds somewhere between 120-150grams to the Take Off Weight (TOW)
I canít believe I did that! (Face palm)

I digress.

Iíd read from WC reports (Roydor?) that the CNHL 650mah 4S batteries are the business.
For the past year Iíve been using 4S Nanotech from Hobbyking without problem or complaint.
Solid power all the way to the top of the launch.
I thought Iíd give the CNHL batteries a shot.
Tuomo suggested that they fit in the canopy area and they do but only at the rear of the open area.
Depending on how the CG plays out, I may get to use them after all.

Explorer Slim fuselage battery (0 min 41 sec)
Dec 31, 2019, 05:06 AM
Everything's A Compromise
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Motor choice


This was a tough one.
I have a NEU 1102/3.5Y/5.8 (P22) in my V2 and Iíll admit to wanting for more power on 3S.
Once I added the 4S Nanotech I be like ... WHOA! Thatís what Iím talkiní Ďbout!
Two things conspired against using that combo again.
Firstly, itís listed as a 3S system. Yes, itís performing famously on 4S, but for how long?
Secondly, the AUDUSD exchange rate. I could get 2 combos from Reisenauer for cost of a single Neu combo.
Thatís not a slur on Neu products, Iím very happy with what I have but weíve all gotta stretch our modeling dollar as far as practical.
After many screen hours of weighing the pros and cons, I settled on the Leopard LC250-30 4040kv.
Not because of any strict criteria or superior understanding of quantum electro-mechanics, it was because theyíd been used successfully before, albeit with fuselage and motor modifications to accommodate the outrunner.
The day after I placed the order with Reisenauer, I thought, ďOh no, ... what have I done? Why didnít I just get an in-runner and keep it simple? Is 25-30grams going to make THAT much of a difference?Ē

Time will tell.
Last edited by Larrikin; Dec 31, 2019 at 06:08 AM.
Dec 31, 2019, 05:28 AM
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Installing the motor


The motor/gearboxes, referred to as just motors from now on, arrived and I assembled the Slim fuse model to check the fit, weight and balance.

It turns out that I didnít need to do a lot of modding to make it fit after all.
The fuse remains full length (not cut back to suit a 32mm diameter spinner) and wires are inside the fuselage (not routed outside for a short distance.)

To have the ESC sit vertically in the fuselage, I wanted the motor wires to run along the side of the motor rather than either above or below the motor.
I chose to run the motor wires along the right hand side of the motor because if I added some right thrust to the motor mount, it would angle the rear of the motor away from the RHS fuselage wall.

My process is to attach the motor mount to the gearbox then incrementally sand the front of the fuselage with a block to create a right thrust bias for the mount to push into.

The Explorer motor mount is blank, ie undrilled. I have a Reisenauer mount that I overlaid and taped to the Explorer mount then transferred the holes from the Reisenauer mount to the Explorer mount.
Last edited by Larrikin; Jan 02, 2020 at 07:18 PM.
Dec 31, 2019, 06:25 AM
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RX location


This is another topic that requires some lengthy contemplation.

Given my (light weight) motor choice and the unexpected boom length, Iím thinking Iím going to require all possible weight in the nose. So, thatís where the rx is going, too.
Iím using the (really cool) NaN supplied connector from the fuse to the wing, and maybe a DB9 (or something) from the nose section to the fuselage.
Last edited by Larrikin; Jan 11, 2020 at 06:18 PM.
Jan 01, 2020, 11:00 AM
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Motor barrier


To prevent the battery, ESC or anything in the cabin sliding forward to contact the out-runner, a barrier needs to be installed.
Roy (dor) did a great unit for the U2 on the 3D printer but I must be the only person left on the planet without a 3D printer so I reverted to ye olde method of hand shaping some 6mm light ply.

Thereís so little taper on the slim fuse that creating a taper on the barrier wouldnít work.
I applied masking tape then packing tape around the fuselage in the approximate location of the barrier.
With a short length of 12k carbon, I did a single wrap around the fuselage with the overlap where the motor wires would be and carefully applied thin ca.
Once it had set I just slid the ring of carbon forward off the tape.

The carbon ring was trimmed so that there wasnít any carbon ring where the motor wires were situated.
Thin ca tacked the ring in place then medium ca and kicker secured the ring in place.

Oh, FYI ... the carbon ring and the plywood barrier weigh less than 1.5grams so weíre still a long way in front weight wise, as far as comparing this motor to say a Tenshock 1515.
Last edited by Larrikin; Jan 10, 2020 at 06:05 AM.
Jan 01, 2020, 07:16 PM
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Slim Fuselage wiring.


Borrowing a couple of images from Aaro, the supplied Slim fuselage wing/fuselage connector is intended for the installation of the Rx in the wing and is wired accordingly for 2 fuselage servos and the throttle. Placing the Rx in the fuselage however, requires the 4 wing servos to be wired to the connector.
Basically, I unsoldered all of the wires and started again. What's great about the NAN PCB is that it's designed to accommodate a 4 servo connection.
NAN has arranged the MPX 6 pin connector with the +ve and -ve at each end and the 4 signals in the center.

Note how the wires in the 3rd image are directed inward toward the center of the PCB so as to not foul the servo installation.
The wiring for all of the servos will be routed along the wingseat/fuselage corner at the base of the front servo.
I'll add an image for clarity when have one.
Last edited by Larrikin; Jan 02, 2020 at 12:30 AM.
Jan 10, 2020, 04:11 AM
Everything's A Compromise
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If, like me, you thought you’d make your own control horns and pushrods to add your own personal touch to the model, stop, snap out of it and give yourself an uppercut. Buy what you need from SERVORAHMEN and save yourself the angst and frustration ... along with a bunch of hours.

Don’t do it this way.

Explorer Big Flap install (1 min 4 sec)


David.
Last edited by Larrikin; Jan 10, 2020 at 05:46 AM.
Jan 19, 2020, 11:48 PM
Everything's A Compromise
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Flight Report


This is hands-down, without doubt THE best thermal soaring model I have EVER flown.
That’s not just lip-service to justify the purchase.
I foresee that the ballast (TOW = 1560g) will stay in for all but the stillest of conditions.
It brought the model to life!
Still working bubbles 5-10 mtrs above the ground with total confidence.
And when it gets away, it’s got the legs to come back.
I’m so very impressed.
I don’t know if I’d notice the difference between the tail moments of the Slim and the Normal fuselages, I just know I want another one of these.
The motor is performing as expected. No problems due to being an outrunner in a Slim fuselage.
The motor and ESC are barely above ambient temp when checked after landing. The battery is warm.
Today was adjusting the landing compensation and feeling the roll rate etc.
So far, I love it.

I’ll add details of the ballast ASAP


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