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Old Jul 24, 2012, 01:13 AM
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4F200 Stock Head Speed 4,470 RPM

Back to the 4F200...


Subject: 4F200 Stock Head Speed 4,470 RPM

I've wanted to do this my self for a while now.

I have confirmed and verified the stock max head speed using a tachometer (a recent addition to my tool kit). With the stock battery, stock esc, stock motor and stock pinion the head speed is 4,470 RPM. This is a reading from the main blade grips with main blades removed and 0 degrees pitch on the tail blades. Please note this is not a "no-load" reading.

My readings are very similar to dkfuji's readings here where dkfuji measured a 0 degrees pitch max head speed of 4,320 rpm.

Consider the following static rc helicopter head speed formula:
HS = (motor KV x Battery Voltage)/(Main gear teeth/pinion teeth)

Plug in the 4F200 stock parameters...

4744 rpm = ( 6000kv x 8v ) / (172teeth / 17teeth )
I say, without taking brushless motor efficiency into account, the formula outcome is pretty darn close.

Now I have a reference point to work with.
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Old Jul 24, 2012, 05:43 PM
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United States, FL, Palm Coast
Joined Mar 2012
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Quote:
Originally Posted by razorblade View Post
Back to the 4F200...


Subject: 4F200 Stock Head Speed 4,470 RPM

I've wanted to do this my self for a while now.

I have confirmed and verified the stock max head speed using a tachometer (a recent addition to my tool kit). With the stock battery, stock esc, stock motor and stock pinion the head speed is 4,470 RPM. This is a reading from the main blade grips with main blades removed and 0 degrees pitch on the tail blades. Please note this is not a "no-load" reading.

My readings are very similar to dkfuji's readings here where dkfuji measured a 0 degrees pitch max head speed of 4,320 rpm.

Consider the following static rc helicopter head speed formula:
HS = (motor KV x Battery Voltage)/(Main gear teeth/pinion teeth)

Plug in the 4F200 stock parameters...

4744 rpm = ( 6000kv x 8v ) / (172teeth / 17teeth )
I say, without taking brushless motor efficiency into account, the formula outcome is pretty darn close.

Now I have a reference point to work with.
I have also clocked the head speed with my phone at 4400 rpm approx. using the stock motor. I am currently pulling about an even 4000 rpm with the Turbo Ace 352 motor using a 18T pinion. I'm fairly sure it can still handle a 19t or 20t to get it up to stock head speed. But honestly, 4000 rpm is pretty damn sufficient. I sure do enjoy flying 5 packs back-to-back on the turbo ace motor without any worry of heat though. I will probably try the viper motor next. However, i cannot find a proper pinion for that size shaft to match the 4f200 main gear. It's really been pissing me off lately too because it's probably the only motor out there that might have a chance at out performing the stock motor. the modulus is just too non-standard, as well as the 2.5mm shaft hole. It's making it impossible. I'll have to order a 2mm shaft pinion and drill it out the rest of the way. Or email my pinion guys and see if they can come up with something.


I'm looking for a 0.3m pinion in 16, 17, 18, 19, and 20 tooth to fit a 2.5mm shaft. If anyone knows somewhere.


I almost ordered a tach last night.. Which one did you get? I'm sure you selected one that can do up to 3 blades... I need one that can do up to 5 blades preferably. Any ideas? I can only find 4 blade ones. I'm also considering using the 18T on the stock motor to see how that goes. Will probably raise the HS about 200 rpm or so. I bet that alone will be better then getting the viper motor.
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Old Jul 24, 2012, 09:59 PM
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Quote:
Originally Posted by IntegrityHndywrk View Post
It's really been pissing me off lately too because it's probably the only motor out there that might have a chance at out performing the stock motor.
Just go with 3S. It will be less frustrating and more enjoyment. If your goal is to out perform stock motor and pinion while staying with a 2S battery, then a higher 6500kv motor is needed or better. Otherwise your just compromising speed for torque, vice versa.

As for me, I am going to stick with stock 6000kv motor and 17T pinion as long as I can until it's no longer available. After that I will go with a 3S battery setup. I already know how stock 6000kv feels in flight.

Just imagine what it would be like if you could have 4,900 head speed with a 15T pinon and 3S 4800kv motor? You'd have both the speed you need and torque.
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Old Jul 24, 2012, 10:07 PM
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Quote:
Originally Posted by IntegrityHndywrk View Post
I almost ordered a tach last night.. Which one did you get? I'm sure you selected one that can do up to 3 blades... I need one that can do up to 5 blades preferably. Any ideas? I can only find 4 blade ones.
I got this one for $15.46. It simply works by placing reflective tape on the target. So it will work with any number of blades. It doesn't care about the number of blades. It only counts the reflective tape. You can use it to measure RPM for anything where you can stick reflective tape.

What I did was just stick a .5 inch piece of reflective tape atop one of the blade grips. Works great for the price and is accurate enough.

http://www.ebay.com/itm/ws/eBayISAPI...E:L:OC:US:3160

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Old Jul 25, 2012, 09:01 AM
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Well i had my nephew at the field and put him to work! He used the camera pretty good. I just wish i had brought a better camera!

The heli is outfitted with the Turbo Ace 352 motor, 18T pinion.

4f200 - 3d flight with new camera man! (4 min 5 sec)
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Old Jul 26, 2012, 03:31 PM
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United Kingdom, England, Enfield
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Well, I've been experimenting flying my 4F200 using the RX-2618V-D with every combination possible.....stock motor, V200 motor, stock 4F200 pinion on the V200 motor, 2S and 3S batteries, stock servos, Hitec servos and MG servos, stock blades, foam blades, esky CT blades, longer tail blades, V200 two blade head setup and everything inbetween.

I still couldn't get it flying right though. The tail continued to rotate to the right or counterclockwise looking from above. I knew that the RX was good, my V200 flies great with it. I wasn't even going to attempt flying with the stock RX because the 2603 TX is a pile of crap.

The only constant factor that's worked is the slipper clutch I made and in any case is adjustable from fully locked tight to a large degree of slip.

There have been so many variations of flight behaviour with all these different setups, it's difficult to explain them all but I have a few fundamental observations:

1. You can use a 3S battery with the stock 4F200 setup. Head speed is a lot higher though and a bit nerve racking. Flies pretty smooth.
2. You can use the V200 motor and pinion with a 3S and 2S battery. The higher torque requires more gentle throttle stick movements. Cyclic adjustment is difficult in terms of height because the head speed drops much more with small movements of the stick.
3. With a 3S battery and V200 motor and pinion, the tail has a hard time remaining still. The torque is too much but with longer tail blades, it's manageable.
4. The type of main blades makes a huge difference to how it flies. The stock CF blades give instant cyclic response but a jerky ride. Plastic blades make for a much smoother flight but they are a lot heavier which means more gyroscopic effect which makes the tail want to rotate.
5. Don't use foam blades at all. The ones I used broke at the root with the high head speed and scared me half to death.
6. For some reason I can't explain yet, swopping and changing between motors and 3S and 2S batteries seems to effect the head holding function of the gyro. Sometimes it would be fine but other times the tail would rotate very quickly making it impossible to fly.

In regards to point 6, could anyone recommend a suitable UBEC for this heli ? because I'm 99% convinced that the RX is having a difficult time with these different setups of servos and motors etc and that, in tern, is effecting the tail head lock function. I wont go into details right now because it bores even me but I think it's due to the changing voltage that the RX is receiving.
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Old Jul 26, 2012, 03:44 PM
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My current setup, spent a lot of time getting this damn fues to fit plus I'm running the V200 head setup and 3S Gen Ace 800mah batteries until I can get the stock 3 blade working properly..if that will ever happen!
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Old Jul 26, 2012, 10:30 PM
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Yes!!!

My EMAX ES08MD servos arrive today along with some other stuff. Took damn near 3 weeks to arrive from hobby-king. One thing for sure, they feel heavier.

Stay tuned for more details...
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Old Jul 26, 2012, 10:31 PM
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Does anyone know if the 2612 or 2618 receivers can handle 5.5volts or even 6volts on the BEC circuit?
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Old Jul 26, 2012, 10:34 PM
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Originally Posted by BenVK View Post
My current setup, spent a lot of time getting this damn fues to fit plus I'm running the V200 head setup and 3S Gen Ace 800mah batteries until I can get the stock 3 blade working properly..if that will ever happen!
I like your heli!
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Old Jul 26, 2012, 10:37 PM
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Just bought some of these metal gear digital servos. At less than $4 a pop, they got to be worth a try. Will report back on that.
http://www.hobbyking.com/hobbyking/s...5kg_0_08s.html
BenVK,

How did these servos work out for you?
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Old Jul 27, 2012, 03:34 AM
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So far so good on these servos. Only had to modify the mounting tabs a bit to get them to fit. They're plenty fast enough and have handled a few small crashes with no problems.

Quick question for you guys. The motor on my heli doesn't start spinning until I get to about 20% throttle stick. I've tried 2 different ESC's and they both do this. Is there a way to "re-set" the throttle range?
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Last edited by BenVK; Jul 27, 2012 at 05:48 AM.
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Old Jul 27, 2012, 01:19 PM
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Seems like 3 is an unlucky number for me.

Got it flying perfect this afternoon with the 2 blade V200 head, 002 motor and 3S batteries. As soon as I put the 3 blade head back on, the tail started spinning again and 2 tail servos died within 5 minutes of each other.
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Old Jul 27, 2012, 05:11 PM
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United States, FL, Palm Coast
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Originally Posted by razorblade View Post
Does anyone know if the 2612 or 2618 receivers can handle 5.5volts or even 6volts on the BEC circuit?
I'm pretty sure the RX will pass the voltage fine. But stock servos will fry above 5.0v. I've been told i can use 6 volts on my 2702V with my savox servos. But have not tried yet. 5.3v is enough right now. But ESC wise I'd be happy to gamble my 2612 on it for you. Only problem is I don't have any 6v servos out of the box. I can try with stock servos though using my hobbywing esc.

Oh, and i've been using the scorpion oil on the 4f200 main shaft bearings. So far so good. Can't wait to hear more about the servos.

Quote:
Originally Posted by BenVK View Post
So far so good on these servos. Only had to modify the mounting tabs a bit to get them to fit. They're plenty fast enough and have handled a few small crashes with no problems.

Quick question for you guys. The motor on my heli doesn't start spinning until I get to about 20% throttle stick. I've tried 2 different ESC's and they both do this. Is there a way to "re-set" the throttle range?
What 2 ESCs are you using? The stock Walkera ESCs are atrocious. You can check a few things though. Look at your TX monitor and make sure your throttle range is moving fully (make sure throttle curve is linear to 0-100 too). If all of that is proper then move to question the ESC and motor. Consult the owners manual if your using an "aftermarket" ESC, for throttle range calibration with the ESC. The walkera ESCs have no settings or reset that i'm aware of. They simply work then go bad. Once you do the calibration. if the issue still exists. Well, it's probably the motor or the pinion might be set wrong and cogging. It's been said that if you fly your 4f200 stock motor on 100% flat throttle it will run too hot and break down and degrade quickly. This is why i lube my motor bearings.
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Old Jul 28, 2012, 03:03 AM
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Only have the stock 20A Walkera ESC's at the moment.

What would you recomend as a replacement?
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