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Jul 21, 2019, 05:12 AM
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So your 4S attempt weighed only 12 grams more plus the adapter.
You said 15 flights on 2S. I'm guessing that's a typo and you meant 3S. If it was 2S the plane would barely fly, if at all.
If it was 3S, how did the 15 flights go? With only 12 grams more weight and 4S power you should have seen a big difference in performance.
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Jul 21, 2019, 08:30 AM
Registered User
sorry, yes u r right, i meant 15 flights on 3s. performance was anemic. she’d fly but definitely not fast and could barely loop. she’d fall out of a loop at the top and could only get into a partial loop by diving into the loop. she would be flying at full throttle the entire time. on 4s i wasn‘t full throttle but about 75%. she could loop but she really didn’t like turns. that extra weight really made her dive in any bank. i’d have to go to full throttle just to keep a level turn. it wasn’t much fun to fly. she definitely lost her floaty feel. but the 2x 2s950 batts were definitely older and lower C (for whatever that is worth since most companies exaggerate C value).
-beanie
Jul 21, 2019, 09:33 AM
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Joe 1320's Avatar
My guess is this was one reason for the extended nose. A lighter battery, but pushed forward to get the right CG. This bird might be a good candidate for a pusher prop conversion. There would be a significant weight reduction in the tail. More power too!

If retaining the edf, any chance of moving the edf units forward an inch?
Jul 22, 2019, 12:19 AM
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AntiArf's Avatar
Not sure where the ESCs are, but moving them forward would help too, if possible. I'm running light weight Emax 12A units on 6 of these fans on 3s, with no failures so far. The quad Victor het has an SBEC, but the twin airliner simply has diode isolators so the second BEC can come online if the first one shuts down. Both have ballistic power at full throttle. I'd be reluctant to run 4s on the 7000kv motor, as that puts it in the rpm territory of the higher kv 2s version, which has some documented bell explosions. The bell is simply wrapped sheetmetal with what seems to have a spot weld seam on an L type overlap joint. I added aluminum rings cut from lipstick tubes fitted tightly around my bells, to provide a little added assurance so they don't explode. You get a grenade effect, when the magnets fly off in random directions.
Jul 22, 2019, 05:04 AM
Registered User
I think the older lower C batteries are the problem. They recommend 20C but I'd use at least 30C, preferably 35-45C.
We should be able to find 1200mAh or so batteries light enough and small enough to sit forward.
I bought a couple 5000 kV motors just in case the 7000s grenade.
I'm attaching a photo when I had her apart to install the orange motor LEDs. You can see where the ESCs are. The wiring is tight so you'd have to do some splicing to move them. They are tiny and weigh nothing, moving them wouldn't do much. You could move the motors /fans forward toward the cheater holes, but I'd rather try finding the right batteries and moving them around first. When I cut off a few inches from the nose area to make it more scale I left a hollow area going into the nose cone where you can move batteries forward to the tip inside the nose cone.
I think the secret is finding the right batteries.
I also left the ESCs in the open so they get cooled by airflow under the fuselage.
Jul 22, 2019, 07:03 AM
Registered User
wing no- where did you source the 5000kv motors?
-beanie
Jul 23, 2019, 05:46 AM
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Got them on Banggood. Brushless outrunners just like the stock 7000s. I think they were about $9 each if I remember correctly. I bought them along with two 30mm 8-blade fans but decided to keep the stock 6-bladers. The 5000 motors will come in handy if the 7000s explode...
Oct 29, 2020, 04:03 PM
MODDED MICRO MULTIS FPV
MONOAMORE's Avatar
Lemme bring this thread back. Maidened my Kit version yesterday on 3S, 1000, 40c and upon full throttle overhand fastball launch the bird wanted to nose dive and I had to apply full up elevator to keep it in the air. When it came time to turn a few seconds later it stalled and lawn darted.
Like most of the other posts in this thread, I think CG and battery selection are critical in order to get it to fly properly.
I’ll have to weigh mine too because there’s an awful lot of wiring in there with the 20 amp opto escs, micro bec, servo extensions and power wires.
I just can’t believe the suggested lipo is a 3S-1500mah 25c!
I’m sizing up 650-850 4S lipos now as a potential solution to the power to weight problem.
May have to go back in a cut weight in wiring and connectors etc and use smaller ga and direct solder where I can.
I saw someone mentioned thrust tubes and moving the fan forward. We’re talking about Focused exhaust tubes right?
Larger intake cheater holes?
Oh and BTW those QX twin 30s do sound great. That sound is what has kept me from giving up on this project.
Matt
Oct 29, 2020, 05:09 PM
Registered User
hey monoamore- i had a very similar sense with my bird. i felt like i was full throttle and barely flying. i wouldn't even bother trying to loop or roll. i think moving the CG back at least for me would make a huge difference. i've also be toying with the idea of 4s, but am trying to figure how to do it.
definitely interested in hearing about your progress.
-beanie
Oct 30, 2020, 06:13 AM
MODDED MICRO MULTIS FPV
MONOAMORE's Avatar
Quote:
Originally Posted by beanie
hey monoamore- i had a very similar sense with my bird. i felt like i was full throttle and barely flying. i wouldn't even bother trying to loop or roll. i think moving the CG back at least for me would make a huge difference. i've also be toying with the idea of 4s, but am trying to figure how to do it.
definitely interested in hearing about your progress.
-beanie
I think it’s also very heavy. Nearly 300g dry! I pulled the electronics, except the servos and fans and still was pretty heavy. I think I’m going to need to rebuild it really light and I might be able to get better results. I’d heard that these QX 30s had a lot of power so I figured 2 of them would have it flying well even with the extra weight. Still gotta figure out a lipo solution. Maybe a high C 4S 650.
Oct 30, 2020, 08:12 AM
Registered User
I've had success with the stock ARF with an 850 mah 3S NanoTech shoved as far FWD as possible (still allowing the canopy to latch). I slightly enlarged and beveled the cheaters (not sure how much that helps). It flies good for what it is. It'll loop and roll (with a lot of aileron travel).

I want to try 4S but I don't know if the ESC's would handle it.
Oct 30, 2020, 08:42 AM
MODDED MICRO MULTIS FPV
MONOAMORE's Avatar
Quote:
Originally Posted by cosmocop1
I've had success with the stock ARF with an 850 mah 3S NanoTech shoved as far FWD as possible (still allowing the canopy to latch). I slightly enlarged and beveled the cheaters (not sure how much that helps). It flies good for what it is. It'll loop and roll (with a lot of aileron travel).

I want to try 4S but I don't know if the ESC's would handle it.
That nanotech is the 25c continuous variety?
I’m running mini quad escs rated for 20 amps and the motors on the fans max out at 12a And 120w each so I think I have some headroom to run 4s.
Nov 02, 2020, 09:17 AM
Registered User
Quote:
Originally Posted by MONOAMORE
That nanotech is the 25c continuous variety?
Iím running mini quad escs rated for 20 amps and the motors on the fans max out at 12a And 120w each so I think I have some headroom to run 4s.
No, they are the advertised 45-90C ones.
Nov 22, 2020, 09:36 AM
MODDED MICRO MULTIS FPV
MONOAMORE's Avatar
OK, I got her down a few grams and installed mostly all of the electronics in front of the CG mark.

Since I bought this as a kit, I used my own ESCs which are a pair of Hitec Rotor 18 opto with the standard QX30 fans and 7000kv motors. A micro 2a, 5v BEC powers the receiver. Power from the battery to the motors is wired through a micro PDB. I'm using a Revolectrix 4S, 1100mah, 70C peak Lipo pushed pretty far back in the cabin bay.

I set up the control surfaces like elevons so both the aileron surfaces and elevator surfaces operate together. Rates pretty low at about 50% and 50% expo.

The launch and maiden were uneventful. It took a while to spool up and I had to keep it at full throttle throughout the flight. It wanted to stall on sharp turns, but some down elevator and limited roll input kept it flying.

Out of a high dive WOT it was screaming!

BH Mini MiG 29 Maiden on 4S (3 min 26 sec)
Nov 22, 2020, 10:02 AM
Registered User
nice job! looks like she has more power. i could barely get mine over 20 ft or so despite full throttle the entire time.
-beanie


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