Faststar

Heliko

What do you think about this BL motor.
My LHS tells me that people are using this motor
on the blade pro and a forum member from another group
has used this for the axe cp apparently with good results.
The only thing they did not state was how much this shortened
the flying time. I know that this motor seems to be over kill but
I thought maybe since you like to crunch numbers that you could
give me your opinion. Here is the link for the info on this motor.

http://www.e-fliterc.com/Products/De...rodID=EFLM1000

The motor fits seamlessly to the axe and it comes with a 10 tooth pinion
that matches the main gear to a tee. I also have checked this at my LHS.

Thank you.

Faststar.

mrasmm

hrm, yeah, that motor is very powerful =) That's what all the pro's run on the bcpp like nick maxwell and kyle stacy. Should work just fine on the axe I believe, but I don't own an axe, I've got the bcpp =) As far as flight time, because the motor is more efficient than the brushed motors (doesn't tak too much =P), even though they produce more power, they take right around the same amount of elecricity, sometimes even a tad less depending on how agressively you fly.

osterizer

I have that motor on a BCPP, too-- works great there, and when I have it set up well I'm looking at 10-12 minute flight times, but I wonder how the all-up weight compares to the AXE. The blade weighs in at about 330g at takeoff.

Heliko

Faststar,

I looked at that motor as well. It's looks to be a good motor, but may not be enough for the Axe. I did an amp test on the motor I installed and it was pulling around 10 amps at full throttle and around 5 amps in a hover. Granted my RPM's are way up and my motor may not have the efficiency of the 370, but still the Axe weighs alot more than the Blade. The 370's continuous amp rating is 8 amps so it may be just enough, but I would look for a motor with a bit higher rating, 12-16 amps maybe.

I'm waiting for a [link=https://www.unitedhobbies.com/UNITEDHOBBIES/store/comersus_viewItem.asp?idProduct=4875]Feigao 2900 Kv BL[/link] right now and will know more after I install and test it. I'm hoping it has enough power because right now choices are limited. Due to the Axe's oddball gear pitch you need to use the stock pinion. It's a 14T and only fits on a 2.3mm shaft unless modified. To get a target headspeed around 2500 RPM you'd need a 2900-3100Kv motor with a 2.3mm shaft. I've heard alot of people say they found pinions that should work, but as of yet I don't know anyone who has actually installed and used a different pinion. My advice on this would be find some pinions that may work and get them before the motor. If they work, great. If not then at least you haven't purchased a motor that may not work because you can't find the right pinion. I know Helimax has some due for release, but as of yet Tower hasn't gotten them in stock.

This brings me back to the 370. It's Kv rating is 4100. I saw a video recently where a guy installed this motor in an Axe. He said that he was able to use the 10T pinion that came with it, but the 12T wouldn't mesh correctly. That right there tells me that those pinions may not be exactly right for the Axe.

As far as other motor options I know of there's the [link=http://www.helidirect.com/product_info.php?cPath=44&products_id=1609]E-sky 3100Kv outrunner[/link] and the [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXKKK8&P=0]Ultrafly 2800Kv BL[/link].

Well that's all I have for now.

Heliko

Oster my Axe's AUW is 526g!

Faststar

Thanks Heliko.

I will take it slow for a while and see what you come up with.

On another note I have fried the brushes out of 2 tail motors.
I talked to the LHS today and they gave me a brushless motor
they believe will solve this problem for me. It is their name brand (Areo Tech)
I have no specs for this motor just that it is a #36 and a lot of people are having success with it.
I also got a Electrifly ss 8amp esc to go with it. Plus a blade that will fit it in the event I want to try a DD tail rotor.
It will take me a couple days to see how this works out and I will let you know.
I am also using a DX7 Tx. and the AR7000 Rec. along with a 401 gyro for this setup.

Faststar.

Heliko

That's really cool Faststar [8D]

I'm looking forward to your results. [sm=thumbs_up.gif]

mrasmm

wow, 526g? My AUW in my cpp with super skids plasti blades 1250mAh lipos extra flybar weights and the dual tail and the rest of it is like 341g

How many amps does the stock motor draw on your heli @ 8v and full collective (if you can manage that kid of specific test =P)?

Sounds like you know alot more about it than I do =)

Have you ever tried a stock 370 brushed eflite motor in your heli to see how it does? That might be a good comparison to start with.

What size of motor are you using? The eflite one is a 0.6 ohm 370 sized brushed motor.

Heliko

I guess my scale could be off Mrasmm.

Anyway I did take some readings a while back and here's what I got.

Main motor (380) max volts/amps/watts
9.92v/11a/109.12w

Hover amps: 5.3A

Tail motor (N60) max volts/amps=watts
9.1v/2.4a/21.84w

mrasmm

I think that n60 is pretty close to that cn12 motor, and that's also what that one draws.

It looks like the resistance on your stock motor is 0.9 ohms, but your motor does draw alot more current to hover. Hover on the cpp draws like 3.5A, and the fuse we use is a 7.5A on the main motor for the fuse mod. Max stall current on the stock eflite motor is 20A. Average current draw for the whole heli with the 370 main and the n30 is 4A, so an 800mAh pack will run for 12 min on a hover. How does that compare to the axe?

Heliko

Hey Mrasmm,

An 11.1v 800mA Li-po would probably provide around 7 minutes of hovering in the Axe. I'd guesstimate the Axe is pulling around 6.5 total amps in a hover. If you think about it makes sense. The Axe weighs almost twice as much as the Blade and as my sig says gravity is a harsh mistress.

Getting back on track, most of us running Li-Po's are running much larger packs like the Thunder Power 11.1v, 1320mA packs, or the DN Power and Mega Power 11.1v, 1350mA Packs. They all provide near the same flight times. I have the DN Power Li-po's and the stock motor set-up produced 12-14 minute hovers. The BL set-up I have now produces 11-12 minute hovers. That decrease in flight time probably has alot to do with the added induced drag from the main rotor's higher headspeed. The new lower Kv BL motor I have coming will answer that question.

BTW someone here tried the 7.5A fuse mod on an Axe CP, but the fuse blew during flight and caused a crash.

mrasmm

hrm, then yeah. It sounds like your system draws quite a few more amps then, and maybe that 4100kv would work, but it wouldn't be nearly as hot as it is on the cpp =)

Heliko

BL update
… got the new motor installed

Well I installed the Feigao 2900Kv BL motor today and it works great. It draws about one amp less in a hover and two amps less at full throttle than the 3400Kv. That should mean flight times should increase by about 20% to around 13-14 minutes up from 11.5. Not too shabby.

With a full Li-Po the Feigao’s headspeed RPM's are 2500 in a hover and 2700 at full throttle, and with 10 volts left in the Li-Po about 2200 in a hover and about 2400 at full throttle.

I also did a temp check on the motor and after 10 minutes of constant hovering the Feigao’s motor temp was about 150º which is about 10-20º cooler than the 3400Kv and that’s without a heatsink. I read that as long as the motor stays below 180º it should be fine, but I may throw on a heatsink anyway. Also FYI the Feigao doesn't come with bullet connectors so I bought [link=https://www.unitedhobbies.com/UNITEDHOBBIES/store/comersus_viewItem.asp?idProduct=68]these[/link].

Now onto the BL tail motor. [] I tried a DD tail and the BL motor temp jumped from the usual 98º after a flight to about 130º and though the tail didn’t whip as much it still didn’t work well. Though the BL tail has plenty of power and no brushes to wear out due to it's slower reaction time when compared to the brushed motor I can't seem to get rid of what is called Brushless-Bounce-Back and apparently neither can anyone else. If I were a better pilot I might be able to compensate for it, but I’m not there yet.

Anyway you cut it though one thing is certain. The BL tail makes the heli harder to fly especially in wind. I believe someone will eventually come up with a gizmo that will smooth out the communication between the gyro and the BL tail, but until then I’m going back to a brushed tail with a Pixie 7 ESC. []


Anyway here are some pics of the new motor and one of the DD tail…

PilotLight

My Feedback: (1)

Glad to hear the brushless Main motor is working for you. If it's possible, time a flight until the battery is getting low and let us know how long it flies. Just becareful the ESC doesn't completely shut down the motor when the voltage gets low.

If you get nearly 15 minutes, I bet alot of guys will do this mod just for the increased flight times!

Heliko

I will Pilot Light, but a full 15 minutes is pretty optimistic for the Axe. Don't forget The BL motor is no doubt more efficient, but I added alot of weight between the gyro, ESCs and all the extra wires.

One of the cool functions of the BL ESC I used is 'soft cut'. When it reaches it's cut-off of around 9.8 volts the motor slows and the heli just settles to the ground. It's actually kind of funny because I hadn't read about that that function and accidentlly turned it off when I was messing with the ESC programming. I was in about a two foot hover and the engine just stopped. Luckily it was out in the yard so the grass broke the fall. Live and learn.

Heliko

Well I was pointed to another thread yesterday by a fellow poster on RC Groups. It was a BL tail thread I hadn't seen. I found some good info there which made me start playing with the timing. This hadn't occured to me. Going from a low to medium setting on the timing seemed to improve tail behavior. I tried the high setting too, but it worked just like the low setting. I'm also in the process of readjusting the gyro. It's already below 50% and that seemed to help a bit as well. I say "in the process" because some broken parts have the heli O.O.C. for now till new parts get here. It's still not perfect, but so far the whipping has decreased dramatically. Now the wind mostly makes it wag as it fights the wind. You still can't go full piro without the bounce-back effect, but it's good enough for me to stay with it for now.

BTW the reason I broke parts was not due to the BL tail acting up. I was just having way too much fun and got carried away. I've got tail in down as well as side in so I was doing a kind of "U" shaped circuit going faster each time and banking hard on the return run. I have a habit of flying N.O.E. (Nap of the Earth) so when I pulled a hard turn and banked a full 90ΒΊ it lost lift and being so close to the ground I couldn't recover, but man was it fun!

Again though I must reiterate the BL tail is working much better, but it's still not as stable as a brushed tail.

PilotLight

My Feedback: (1)

N.O.E. I hear ya. I find myself lookin down on the heli all the time. Trying to get in the habbit of flying higher and looking up at it more often. It's a bit more difficult to find the "level attitide" if you're not looking straight out at it.

Heliko

I hear ya PL it is harder to judge the distance when the heli is overhead.

I can fly higher I'm starting to get used to seeing the bottom of the heli. It just seems like more fun close to the ground with the rotorwash blowing on the grass as it goes by. Plus if I go too high the house no longer acts as wind break and then there's the trees to deal with.

osterizer

Ha. I did the same to the King2 last weekend, Heliko. Got crossed up coming toward me at speed and made a hole . CA and thread did the job til the parts got here, though.

Heliko

It's kinda funny Oster I kinda fell in a vicious cycle lately. I seem to be destroying the same parts over and over. Aside from blade grips now the part du jour seems to be flybars and skid supports. [:@] Oh well.

It's from outdoor flight, lots of room to build up speed. [sm=devious.gif]

Heliko

BL update

I guess it's time for an update. I've put some time on this set-up now. I've also switched over to a 7CHP which I'm still dialing in.

Let's see I added a heatsink to the motor and that dropped main motor operating temps to about 135ΒΊ. I also got rid of the Dean's connectors. The E-Flite EC3's seem to work better with multiple wires for the ESC's.

I also timed a flight with the 7CHP's timer. I got 11m, 52s with a stop voltage of 10.3v. My timed flight with the 3400KV was 11m 25s. Keep in mind though with the 7CHP's timer stops anytime the throttle is below 50%. Unfortunately these two runs aren't an exact comparison because the 3400Kv's flight was timed with a regular stopwatch.

The tail is doing better too. It still kicks a bit with wind and when it bumps the ground. I'm probably just getting used to it. Either way it's working OK for me.

I know I want the impossible. The simplicity and ease of repair of the tail motor set-up with the performance of a CP tail rotor. I emailed Freestyle Hobbies on the advice of a fellow poster and they are working on a belt drive CP tail for the Axe due out in about a month.[8D] Oh boy another upgrade!

timberwolf211

Heliko,
You give me inspiration once I learn to fly my heli. I was on runryder a few days ago and found this mod and think it will be worthwhile.http://www.runryder.com/helicopter/t347958p1/
Also I found the parts of a MX 400 will fit for this mod and run about $30 from tower.

Heliko

Timber I thought hard about doing tail struts as well. I was looking at pieces from the Venom NR. I really like the way it looks, but I just can't justify it. It would serve no functional purpose for me.

My boom doesn't flex during flight and if the boom is struck by the blades or in a crash it will still bend and most likely break or bend the struts too.

Also going seperates forced me to add weight to the back of the heli with the Gyro and ESC's so the last thing I want to do is add more weight out on the boom. Right now the CG's OK, but if the CG moves too far back the heli will become even more unstable then it inherently is.

Weighing all this info I decided against it.

timberwolf211

I understand. I think with all the upgrades you have there you are no longer going to have a AXE but a full blown Baby MX 450 or T-rex; by the time you get done you wont need a better heli you will have it there in front of you. One more question did upgrading to a better raido give you better control over the Axe and give it a more stable feel?

Heliko

That's what I'm going for. Trex 450 performance with a micro.

The Tx actually made it harder for me to fly at first. Unlike many pilots I like the sensitive controls. I used another poster's settings and it was a shock when I first tried the new Tx. I was undercontrolling the heck out of the heli even without expo or duel rates. I'm still learning nose-in and it seems desensitizing the controls for new maneuvers is helpful. I'm also still dialing everything so that factors into my opinion too.

It is nice to have the ability to control throttle and pitch curves, but honestly the Feigao 2900 seemed so well suited to the stock radios curves the new Tx didn't make a huge difference in stability or control for me. I think the gyro made a much bigger difference in stability.