Help...melting problem...

[rkte]

Hi guys,

Need your advise as I just encountered melting problem.
Just maidened Mirage2000 from RICCS this morning with following setup:
- 130 brushless motor 5400Kv
- DualSky 40A ESC
- TP Prolite 2100mA
- Stock Ducted Fan 64mm

The plane took off around 25 meter coz only apply half throttle all the way
But after 3 minutes, no power at all (power cut)
Glide and land successfully but smell plastic burning, bye...bye... to both motor and EDF case

Thinking to use Himax 2025-4200Kv but wondering will it melt the case also?
Or is it possible to use Mega 16/15/3 on Ducted Fan 64mm?

Thank you.

[Babylon5]

Hi RKTE, the motor 5.3KV motor is not suitable for use with this 65 mm fan with the 6 blade . If I am not mistaken, this motor is rated up to 19amps max.
Did you check the max current at full throttle?. If the motor runs hot it means the motor is drawing current well in excess of its maximun rating.
With 4.2KV motor , the setup will run at lower current but may not develop enough power....worst still it will still run hot.


Unfortunately I don't have a good solution for you. IF I am not mistaken, the 65mm fan can take limited body size motor up to 24mm diameter , therefore limiting its power plant.


I am not sure if the plane of yours can take a wemotec 480 or a Super flying model EDF 68. This two fan can handle bigger and more powerful motor up to 29mm diameter.

Alternately you may want to convert your plane to a pusher propeller setup.

If you are serious in electric Rc flying you should get a clamp on DC ammeter like the Kyoritsu 2000 or similar series available at S Lim. This meter can also read the ESC timing and hence read the rpm of the EDF indirectly.
Best of all it does not introduce resistive element into the electrical systems when you measure the Dc current while the motor is running. All it takes is just place the u shape tongs on either +ve or -ve battery wire to read the DC current. To measure the ESC timing frequency ,select Frequecy and place the tong on any of the 3 wires exiting from the brushless motor.




Cheers and all the best

[rkte]

Hi Babylon5,

Thanks for your advise
Actually, I heard this mortor cannot be used for EDF or direct drive, only can be used for geared.
Btw, I don't have amp meter to check, so only checking how hot is the motor
Now, I'm using the EDF55 kits from TowerPro which is smaller than original fan.
Did a test flight for 5 min yesterday, so far the motor only warm (5300kV outrunner) but my 40A ESC is hot.
Another negative point is the sound generated quite loud when full throttle with no much speed increased
EDF really waste a lot of power , converting to pusher is a better idea

rkte

[Babylon5]

Hi, I have a China made 5.4KV b20-40 motors and it will still run very hot with a 55mm EDF. The current drawn is exceeding its maximun rating of the motor.
It is not suitable for use with the 55mm EDF with the 6 blade.

To use this motor on the 55mm EDF, this is what I do.

1.)remove the original 6blade impeller.
2.)Take a 3 blade 9-7 gws propeller and cut, balance to fit the motor and shroud
3.) Enlarge the modified propeller to fit into a suitable prop adapter.
4.) Make sure you have at least 0.5mm clearance(gaps) between the tip of the modified propeller and the wall of the shroud when you rotate the props.
(too big gaps you loose thrust ,too small gaps and there is a chance the prop will rubs against the wall of the EDF shroud.

If everything works, the motor will be spinning well over 54,000rpm
at around 17-18 amps.
The motor will run hot but will not melt the EDF shroud.
This setup will give you an estimated 420-440grams of static thrust provided you have ample breathing room for the air intake. In another words EDF needs plenty of air to breath to be efficient.

However, 440 grams of thrust may not be enough thrust for the Mirage2000
to fly sucessfully



Cheers and welcome to the duct side

[razerback]

hi, i too had the mirage2000. on my maiden, i using the same 5400 motor as you. after 2+ mins of flight.... motor K.O. on my second flight, i used tahmazo reno 4300kv motor.. motor manage to hold out well, but after a few flight, poff.... another motor & this time 40 amp esc also gone with the wind.. now i've converted my mirage2k to pusher configuration. using align 400SF 2800kv with 4.75x4.75 prop. flies better. to fly EDF plane must hav the right combination of motor & fan & other factors. really admire ppl with nice EDF jet tat flies well

[rkte]

Thanks guys.
At least we now that the recommended motor is NOT suitable for this plane

[Vortices]

hi guys, 5300 kv is too high for anything above 2S. When the fan speed and rated rpm(kv) is too different the amp drawn will increase dramatically.

Assuming you want to continue on 3s. Maximum recommended 3900 kv. Even this has a max power time restriction of about 10 sec continuous, after which the throttle needs to be pull back sufficiently otherwise the core temperature would be catastrophically hot.

Cost is obviously a concern, with all the set that you have, the cheapest fix would be to buy a new motor. Himark 2025 (3500-3900 kv or similar)from SHS would be a quick fix. The dualsky esc need to be programme for high frequency for max efficiency.

From experience, if you can leave the esc outside of the airframe for cooling would be good. Exhaust area must be about 90% fsa (fan swept area) for optimum efficiency. 55 edf fan gws the old version without the impeller screw requires throttle delay of at least 30%, otherwise impeller separation is probable after a while, the new version is fantastic. Anyway 64mm to 55mm is too big a jump. Mirage200 works well on 64 or even 70mm fan.

But if you are really serious about edf, 4s is by far more efficient for small models. something in the region of 300watts 2500-2900kv on 4s.

As for flying, keep this in mind, EDF effective thrust increase with aircraft speed therefore with same throttle stick position at different speed the thrust produced is different. Also as thrust increase is exponentially related to rpm and not linearly, thrust increase and decrease is slow and requires more anticipation (unlike spontaneous response from propeller)

hope this help, spent money and time learning all this the hard way, hope this would help you safe some dough or even more importantly some time.

cheers.
Kevin

[Babylon5]

hi guys, 5300 kv is too high for anything above 2S. When the fan speed and rated rpm(kv) is too different the amp drawn will increase dramatically.

Assuming you want to continue on 3s. Maximum recommended 3900 kv. Even this has a max power time restriction of about 10 sec continuous, after which the throttle needs to be pull back sufficiently otherwise the core temperature would be catastrophically hot.

Cost is obviously a concern, with all the set that you have, the cheapest fix would be to buy a new motor. Himark 2025 (3500-3900 kv or similar)from SHS would be a quick fix. The dualsky esc need to be programme for high frequency for max efficiency.

From experience, if you can leave the esc outside of the airframe for cooling would be good. Exhaust area must be about 90% fsa (fan swept area) for optimum efficiency. 55 edf fan gws the old version without the impeller screw requires throttle delay of at least 30%, otherwise impeller separation is probable after a while, the new version is fantastic. Anyway 64mm to 55mm is too big a jump. Mirage200 works well on 64 or even 70mm fan.

But if you are really serious about edf, 4s is by far more efficient for small models. something in the region of 300watts 2500-2900kv on 4s.

As for flying, keep this in mind, EDF effective thrust increase with aircraft speed therefore with same throttle stick position at different speed the thrust produced is different. Also as thrust increase is exponentially related to rpm and not linearly, thrust increase and decrease is slow and requires more anticipation (unlike spontaneous response from propeller)

hope this help, spent money and time learning all this the hard way, hope this would help you safe some dough or even more importantly some time.

cheers.
Kevin

Hi Vortices, I have a similar B20-40 3900kv motor and they run well on the 55mm EDF on 3 cells LIPO drawing about 18-19 amps. The motor runs hot but would not melt the EDF plastic housing. The Thrust is estimated just over 500grams but may nor be able to give good performance with the Mirage 2000 plane.
Agree, this motor size and KV is probably the set up limit for the GWS or Himodel 55mm EDF.

The B20-40-xxx motor is limited to about 200-250watts of max power so you can't go beyond this power and expect the motor to survive for long.



Cheers

[leonlio]

This meter can also read the ESC timing and hence read the rpm of the EDF indirectly.

This is interesting...
B5 can you please explain in detail how to double the meter as a make shift tachometer?

Thanks.

Cheers,
Leon

[DT8666]

Hi, very sad that I continue to see wrong motor being recommended by the shop. For this stock fan that only can take 24mm motor, DON'T waste your $$ on those Red/Blue motor with no name and kv of 5000! you will have one flight most of the time, I believe I have stated this during one of the SAPAC Hawk discussion.

However, don't give up and don't convert this nice bird to pusher. I hv seen many are flying well and this Mirage can fly like a trainer. Here are some choices for you:

Stock Fan:
- HImax 2025
- 3700: slow flying but you can do full power all the time
- 4200: better setup and you should add a heatsink to the motor.
- Use the Impeller from SFM (Jet has it) and sand down to fit the housing.
- 5300 on 3 blade: very very good performance, heatsink recommended
- you may try 6 blade on lower kv Himax

Wattage Fan:
- Himax 2025-4200 (HeatSink recommended)

For minimum work by sand off some foam to house the larger fan, may need to enlarge the battery holder (relatively easy work):

Good performance on lower budget:
- SFM Fan with can take 28mm motor
- Any 28mm motor with kv of 3500 to 4500

Super performance with almost unlimitted vertical:
- Wemotec Mini Fan on HET 2W or Mega 2T!!
- you will need high C Lipo and 60A ESC
- I tried this setup and you can see the Turbine flyers open up their eyes!

Too bad that I unable to insert the link of more info here (it will auto delete by the forum ). Lazy to retype everthing all over again.

Well, if you still have problem, let me know. Glad to help up!

Cheers to EDF flyers!!

[Alvin Roger]

Hi DT8666,
I had ask a few expert EDF flyer in this forum like Babylon5 about bigger EDF set up (90-120mm). However, was not able to get any answer from him and was asked to go RCgroup for answer.
Btw, appreciate if you are able to advise me on that or do you know anyone here is Singapore who fly 90 or 120mm EDF Jets?
Btw, where do you fly and can I join you guys ?
Thanks
Alvin

[DT8666]

We just flown / maiden a 90mm Mirage that sold by Skyhobbies. Nice flying bird with reasonable power. cruise at 3/4 power (with relatively strong wind condition today).

Again more info available on another forum.

I nomally flying at Tampines Bicycle park. all are welcome.

cheers!

[Alvin Roger]

We just flown / maiden a 90mm Mirage that sold by Skyhobbies. Nice flying bird with reasonable power. cruise at 3/4 power (with relatively strong wind condition today).

cheers!

really hope to watch you guys fly those big EDF Jets.

Btw, is 90mm EDF common in Singapore? Because I can only find info on 50 or 70mm size EDF thread here. I know in RC group, big EDF is nothing new.

[Babylon5]

This is interesting...
B5 can you please explain in detail how to double the meter as a make shift tachometer?

Thanks.

Cheers,
Leon

See this link http://www.daddyhobby.com/forum/showthread.php?t=12483 thread #13

You need to know the number of poles of the brushless motor.
Most inrunner I know are single pole so direct coversion ...so 1 pole motor ( 1hz=60rpm) rpm= no of hz x 60 ....otherwise you have to use the formulate as shown in the link to get the correct rpm from the ESC timing frequencies.

Cheers

[rkte]

Hi DT8666 & Babylon5,

Thanks for all the recommendation
Yesterday, I've tested the plane using 64mm GWS fan, 6 blades and TowerPro 5300kV outrunner.
She have plenty of power and flies quite fast now
The motor, ESC and battery are warm
May be I will join you guys at TBP someday.... or you may join us at woodlands

Cheers,
rkte