Multiplex Heron - Now a Build Thread

[jseyfert3]

I bought a Multiple Heron kit from a local club member. I'm looking at things I need. I had the following things planned now. Any suggestions welcome. This is my first sailplane, but not my first plane.

Motor: Turnigy Aerodrive SK3 3542-1000kv. Mentioned on RC Groups as a good upgrade to the motor that comes with the RR version, and people said it works with the stock prop and gives unlimited vertical climb.

ESC: Looking at the FrSKY Neuron 60 A. While more expensive than say a HK ESC, it looks easier to program and tweak, and I've been wanting current feedback from my planes anyway for integrated mAh display and voice warnings.

Servos: Was thinking Hitec HS-5055MG for the tail servos and HS-82MG for the wing servos. My dad recommended digital servos for the elevator in particular. Probably don't need the metal gears in the tail, but it was the only Hitec I saw that was digital in that size. I've read you want the metal gears for the wing servos or they will get stripped on rough landings.

Rx: Archer GR8.

Battery: Pretty much anything around the 3s, 2200 mAh recommended size.

 

[Konrad]

Great flat land foamy glider! I have a detailed build thread on HIP. https://www.hippocketaeronautics.com/hpa_forum/index.php?topic=21046.0

 

[gp49]

Great glider.
The R&R version was build around HS81's (plastic gear) servos. It might be 'easier' to switch to HS82MG --- same physical size, just a tad slower then the 81 and similar torque. HS5055 are pretty slow, smaller in size to fit the pockets and are about 1/2 the torque of the 81's.... Checkout the 'Emax ES3352 Thin Digital Servo' on the Aloft store side. Pretty inexpensive. Torque and speed pretty close to HS81/82MG

Make sure to 'upgrade' the wing wiring connector between the wing and the fuse to the green MPX connector!

 

[jseyfert3]

The R&R version was build around HS81's (plastic gear) servos. It might be 'easier' to switch to HS82MG --- same physical size, just a tad slower then the 81 and similar torque. HS5055 are pretty slow, smaller in size to fit the pockets and are about 1/2 the torque of the 81's.... Checkout the 'Emax ES3352 Thin Digital Servo' on the Aloft store side. Pretty inexpensive. Torque and speed pretty close to HS81/82MG

Yeah, HS81's in the wings (x4). The elevator and rudder servos are installed into the vertical stabilizer, and are designed around the HS55 servos. In all cases there are pre-molded slots to just slip the HS81 or HS55 servos into place and secure with some glue. I'm open to different servos, but ideally they have the same form factor as the ones that are designed so I can just slot them in without cutting the foam. Hence why my initial thought was the HS5055 for the elevator/rudder and HS82MG for the wings, since they have the same form factors as what it's designed for.

Are there other servos you know of that have the same form factor as the HS81 and HS55 but are better?

Also thanks for making me go look at the wings. I was going to order some twisted servo extenders, but when I looked at the wing to see if they pre-molded for the HS81s just now I realized they pre-molded servo lead slots too, which will fit a regular flat cable but not a twisted cable. So I will switch my Aloft cart from twisted to flat extenders.

Make sure to 'upgrade' the wing wiring connector between the wing and the fuse to the green MPX connector!

I looked this up. Looks like a 6 pin connector. I'm assuming this recommendation is so for each wing you get a single connector for both servos? A connector like that, and use opposite genders on the fuselage side for left and right wings and you have just two connectors which makes it impossible to connect any of the wing servos to the wrong spots on accident when attaching the wings, and no need to fiddle with lables. Nice!

 

[gp49]

Yeah, HS81's in the wings (x4). The elevator and rudder servos are installed into the vertical stabilizer, and are designed around the HS55 servos. In all cases there are pre-molded slots to just slip the HS81 or HS55 servos into place and secure with some glue. I'm open to different servos, but ideally they have the same form factor as the ones that are designed so I can just slot them in without cutting the foam. Hence why my initial thought was the HS5055 for the elevator/rudder and HS82MG for the wings, since they have the same form factors as what it's designed for.

Are there other servos you know of that have the same form factor as the HS81 and HS55 but are better?

Also thanks for making me go look at the wings. I was going to order some twisted servo extenders, but when I looked at the wing to see if they pre-molded for the HS81s just now I realized they pre-molded servo lead slots too, which will fit a regular flat cable but not a twisted cable. So I will switch my Aloft cart from twisted to flat extenders.


I looked this up. Looks like a 6 pin connector. I'm assuming this recommendation is so for each wing you get a single connector for both servos? A connector like that, and use opposite genders on the fuselage side for left and right wings and you have just two connectors which makes it impossible to connect any of the wing servos to the wrong spots on accident when attaching the wings, and no need to fiddle with lables. Nice!

I'm pretty sure Hs82MG is same size as the 81 so that works. Emax3352 is pretty close to hs55 in size, but more torque. Its also a digital. You will have to spend $30+ ea. to get the HS5065. HS65MG is also close to 55's in size but 50% more torque. You can check the specs in aloft store listings, or use servodatabase.com website.. I just like more torque on the elevator then Hs55. That said we never had problems with the original tail servos on our heron. Wing servos are a different story, but I still have gearsets for HS81 so for now thats what we use.

Yes, single connector replaces both jr servo connectors. The jr connectors are a pain in the arse. Other then that you are all set. The wing retaining pin is easy to loose, but it works nicely when your wings need to seperate during rough landings. You can get spare parts from Karlton, current importer .

 

[Flying Dutchman]

I strongly suggest you read @Konrad 's build log, it was very helpful to me.

A few hints and comments:
1. I also used a carbon tube instead of the hexagon shaped FG tube included in the kit. Lighter, and provided more room for pulling through servo leads.
2. This plane was designed around HS-81/82's, specifically the lead lengths, which are about 1~2 inches longer than ANY other servo's I've seen. The connector cavities are designed based on these. I used others (Corona DS843MG), and had to cut new cavities in the foam, and use different length extensions. Although I really like the DS843's, using Hitec's would have been easier/cleaner.
3. Absolutely use those MPX 6-pin connectors. The stock wing connector design is truly silly and an ongoing source of irritation.
4. You will NOT be able to get to the two tail servo's after you've glued the fin shut (without destroying the fin), so pick the best servo that will fit!
5. The HS-82 is indeed the same size as the 81, but no, neither is digital (see aloft product pages).
6. Tie a string to the wing retaining pin and attach it somewhere in the cockpit cavity, so you don't lose it. BTW, that design works surprisingly well!
7. I used an EMax GT2820/985KV motor from Aloft, and it worked very well.

Good luck with it!

 

[jseyfert3]

Great flat land foamy glider! I have a detailed build thread on HIP. https://www.hippocketaeronautics.com/hpa_forum/index.php?topic=21046.0

Thank you! Tons of useful information in there both with the plane, but mixing setups and sailplane flying advice.

On the crow mix, I see you use throttle stick for that. It appears you have no crow at full throttle stick and max crow at low throttle stick? (Since you talked about how it works like throttle when coming in for landing, less stick to drop the glide slope, more to extend it)

Is crow used anywhere else other than landing typically? I know I’m thinking WAY ahead of the cart here, given I still need to order most of the things I need to build this, but my mind just got stuck thinking on this. I’ve got loads of flexibility since I have a Taranis XD9+, so the mixes are unlimited, and I’ve got two pots, two sliders, and a plethora of switches to work with.

I was thinking perhaps have a switch, such that in one post, you’ve got throttle on the throttle channel. Flip the switch and it replaces throttle on the stick with crow, and moves throttle off to the slider. Such that for aerobatics to you maintain full throttle control, but when landing you have fine control over the crow mix. But I can also see that being confusing to have the throttle “move” and it may just be better to stick the throttle over on the left slider and leave it there all the time.

Also I gathered a lot of info on other useful mixes, is there a good reference for further reading up on the various mixes used in sailplanes?

 

[gp49]

You can always keep the throttle and crow on the stick. Upper 50 percent is throttle, lower 50 percent is crow.

 

[Konrad]

I never like the split stick. Control resolution was always poor. I also never knew when the blades would come out.

My transmitters have had a side slider that I can use as a proportional throttle.

I’ve only used crow for landings or trying to slow down a crash. I’ve seen some use it to slow down the down lines of a loop.

 

[jseyfert3]

You will NOT be able to get to the two tail servo's after you've glued the fin shut (without destroying the fin), so pick the best servo that will fit!

Yeah, I realized that too reading Konrad’s build thread. If I pay $20-$30 each for quality tail servos no big deal. Not that loosing an elevator servo is ever a good thing, but I’ll save the $3 servos for flat foam parkflyers.

 

[jseyfert3]

7. I used an EMax GT2820/985KV motor from Aloft, and it worked very well.

Did you use this with a 3s pack and the stock 12x6 prop? Do you get vertical climb?

For some reason the listing on Aloft doesn't show the specs for thrust and current for the 985 kV motor, only the 850 and 1450 kV models. I found a site that listed specs on the 985 kV motor. Comparing the 850 vs 985 kV models to the Turnigy SK3542-1000 (mentioned by multiple people on RC Groups as well as one person in Konrad's build thread) we have:

Brand	Motor	kV	Cells (S)	Prop	Current (A)	Thrust (g)	Thrust efficiency (g/A)
EMax	GT2820/07	850	3	12x6	26	1650	63
EMax	GT2820/07	850	4	12x6	41	2300	56 (42)
EMax	GT2820/06	985	3	12x6	38	1300	34
EMax	GT2820/06	985	4	12x6	36	2200	61 (46)
Turnigy	SK3542-1000	1000	3	12x6	36	1840	51
Turnigy	SK3542-1000	1000	3	11x7	35	1620	46
Turnigy	SK3542-1000	1000	3	11x5	27	1560	58
Turnigy	SK3542-1000	1000	4	10x5	38	2210	58 (44)

Data sources: Aloft (Emax 850 kV), Rc-innovations (985), flybrushless (Turnigy). Thrust efficiency in parenthesis is normalized by multiplying by 0.75 for the 4S packs to better compare to the 3S packs, a sort of pseudo thrust to power measurement.

Seems a little odd to me that the 985 kV motor specs have less thrust than the 850. Perhaps the 12x6 isn't the best match for the 985 kV motor? Probably the best choice for ultimate thrust in the three motors. All three are very similar but the 12x6 on the 985 kV with 4S is the most efficient of the three.

For 3S, the worst combo seems to be the 985 kV Emax with the 12x6 prop. The least thrust, and by far least efficient, if the 38 A is to be trusted.

Looking at this data, I'm leaning towards the Emax GT2820/07, 850 kV motor. Especially with the stock 12x6 prop, this seems to be the best overall. Not the most thrust (though if the manual weight of 1550 g is were I end up, I'd have just barely over 1:1 thrust ratio) and a pretty efficient thrust ratio. On a 2200 mAh 3S, discharged to 80%, this works out to ~4 minutes of WOT, at an easy 12 C discharge rate on the battery. If I ever wanted to do extreme vertical climbing, then I could pop in a 4S 1600 mAh pack and it should scream vertical and still only be at 26 C discharge rate.

Of note, perhaps further indicating the 12x6 isn't the best choice for the 985 kV motor, is that the stock Multiplex motor is also an 850 kV motor.

Now, the problem is that after lining up and looking at this data, and deciding to get the Emax 2820 850 kV motor, is that Aloft is out of stock...

Perhaps just get the 985 kV Emax and throw a 12x5 prop on it instead of a 12x6? I do plan on building a simple mount so I can throw a motor and prop on and measure static thrust myself along with current data. Better yet, the Neuron ESC will make it easy to compare actual in-flight efficiency of various props. So instead of just simple static thrust, I could measure (and log) actual in flight performance. Current, RPM, rate of climb (from the Archer GR8 Rx telemetry altitude data). Add a airspeed telemetry sensor for a complete performance evaluation...

 

[Flying Dutchman]

Good in-depth motor analysis, @jseyfert3. Yes, I'm using a 12x6 and 3s-2600mAh LiPo. No vertical climbs, but that is by design - they suck up too much power, and I don't feel a need for them. I actually limited the output to 80% in order to get more motor time - about 2.5 minutes.

I also prefer lower KV motors, but the 850 has been out of stock for a long time and the 985 was closest in terms of thrust and current draw. Using a 12x5 or 11x6 might be a good idea. My experience with a few Emax motors of this caliber is that they prefer RPM's over big props. You might also consider a 2826/1090 on 3s, which I use in my Prelude. A bit heavier, but also more thrust. Same price, and they're in stock! Not sure why I didn't use that on the Heron, perhaps it wasn't in stock at the time.
That Turnigy with a 12x6 on your list looks good, but I have no experience with them.

Note that the battery compartment in the Heron is tight, so keep that in mind when selecting LiPo's. My HRB 3s-2600's fit exactly (flat), not sure about a 4s.

Unfortunately my kit Heron was destroyed in a mid-air. No other kits were available at the time, so I bought a used RR version from a friend, which had all the std hardware in it. It's OK, but I liked mine better!

 

[jseyfert3]

Finally, finally putting together my order. Got busy for a while, though I did go flying a bunch too, with my current two flyable planes (Turbo Timber UMX and Pulse 15e).

I've decided to go with the Turnigy SK3-3542-1000kv. Going to go with the HS-5065MG servos for the tail. A little on the pricey side, but as mentioned I can't get them out without major surgery.

For props I'm going with an Aeronaut Cam 12"x6" (given that @Konrad reported the stock prop was too flexible, which I also noted just now) as well as 12"x5" and 11"x5" props to experiment given my above chart. Although as I know, and Konrad alluded too in his build thread, static thrusts aren't real life unless you spend much of your time hovering, and your exact prop is going to depend on both your motor and flying application. I plan to use recorded telemetry from vario (altitude), power (from Neuron ESC), and if I add it speed (from pitot tube and sensor). I'll try one prop, review recorded data, swap prop sizes and repeat, then compare the data to see which prop is best.

Thinking of adding pitot tube speed sensor (FrSKY SPASS-70), but not sure if I want to cut a long channel in the wing to run the pressure tubes. I did find one Heron set up for FPV with such a setup though...

That's about it for now, will update further when I have more progress.

 

[jseyfert3]

Unfortunately the servos I wanted were all out of stock on Aloft, so I will have to get those elsewhere. And I couldn't find the MPX connectors, they are either out of stock or one of the items Wayne mentioned haven't been added back to the new website yet (couldn't find them saying out of stock either).

Battery I'm planning a Turnigy 2560 mAh 3S based on @Flying Dutchman and @Konrad's use of similarly sized batteries.

 

[jure]

..And I couldn't find the MPX connectors, they are either out of stock or...

are you looking for these ?
https://alofthobbies.com/products/6-pin-wing-connector

 

[Konrad]

The Heron uses the standard JR style connectors 4 each. I'm one of the few guys that actually liked the auto plug in feature of the Cularis. Multiplex did away with the auto feature on the Heron but went back to the six pin and auto connect with the Lentus.

 

[Flying Dutchman]

are you looking for these ?
https://alofthobbies.com/products/6-pin-wing-connector

Those are indeed the ones I was talking about, and apparently they are in stock at Aloft.
I strongly recommend using these instead of the wacky system used in the Heron. One day I'm going to rip them out of mine and replace them with the MPX connectors.

 

[jseyfert3]

are you looking for these ?
https://alofthobbies.com/products/6-pin-wing-connector

Yes, thank you! I send them a message to see if they could throw those into the order I placed last night.

I strongly recommend using these instead of the wacky system used in the Heron. One day I'm going to rip them out of mine and replace them with the MPX connectors.

Yeah, I was unfortunately searching MPX connector last night. They were able to recover most of my cart after the website update, but apparently these connectors fell through the cracks.

What funky system did the Heron RR come with? To my knowledge, the kit version (which I have) doesn't have any connectors. You're just supposed to use the servo connectors. But dealing with four separate servo connectors each time, and the possibility to plug them in wrong, wasn't to my liking.

 

[Konrad]

They both have the same "system". The female is held in the fuselage and the male connector is loose in the wing. You're not likely to plug them in wrong as the wing does have a guide feature.

 

[jseyfert3]

I haven’t dug into what they’ve included in the kit for connectors. I did contact Aloft and they told me to put in an order for the 6 pin connectors as pick-up to avoid shipping charges and they’d have shipping throw these into my existing order.

Great customer service here and they get back to any questions faster than any other online store I’ve ever used. I love it!

Also I did want to get an aluminum spinner, but the biggest Aloft has is 50 mm and I measured 55 mm for the Heron stock plastic spinner. I measured at the widest part of the back of the cone. Is this the appropriate point to measure a spinner? I’ve never ordered a spinner before, just always used the stock ones. I’ll probably start with the stock plastic one but I’d still like to upgrade to aluminum at some point.