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Old Apr 08, 2002, 10:23 PM
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Canada, BC, Capital Regional District
Joined Feb 2002
23 Posts
New Logo 20 flies great, but some questions

I've got my Logo 20 flying and it's awesome! Much more stable than my Piccolo and incredible power. It required only minor trim adjustments and then flew great - it practically flies itself! (That first liftoff was a bit nerve racking). The big thing I notice is the noise - it sounds like more like a real turbo prop aircraft, compared to the almost silent Piccolo.

I have a number of questions - I'd appreciate it if anyone can give me some ideas.

First, my setup is as follows:

Motor: Plettenberg 300/25/A3 with Future 35ho speed controller
Servos: JR9311 digital servo, Futaba GY401 gyro (delay=10, limit=100) with 9253 servo
Radio: Futaba 9CH transmitter with Futaba R309 PCM receiver
Batteries: Receiver - 4 cell 720mah Nimh, Main - 24 cell Sanyo RC3000 HV
AUW: 3.7 kg (Battery 1.5kg)
Flight time: 8-9 minutes, Motor temp: 62C, Battery Temp: 43C, Ambient: 10C
Main Battery Charge ~2800ma, Receiver Battery Charge ~150ma
(Note that when the battery starts giving out, I land instead of running it until it's completely dead)


Questions:

1. When I initially start the motor, the helicopter spins around 180-360 degrees until the the rotors get up some speed (Maybe 500 RPM?). Is this normal?

2. Whenever I connect the main battery to the speed controller (after the receiver battery is connected), there is a spark! Is this normal? (I generally think sparks are bad for electronics)

3. After flying, I land and quite often the motor doesn't stop at zero throttle. I need adjust the throttle trim down 1 click to stop it. Why would this be happening?

4. In speed regulator mode, the motor surges up and down noticeably while starting up. Once it reaches full speed it seems very stable. Is this normal?

5. Lubrication - Is it ok to use silicon spray on everything i.e. ball links, swash plate, main gear, tail slider?

6. I'd like to get a carbon tail rotor to match the main. None of the ad's for carbon tail rotors indicate the root thickness (5mm on the Logo). Are they all the same? Does anyone have any recommendations?

7. Is it better to use higher RPM (and thus less pitch) or lower RPM to get longer flight times? (I'm practicing hovering at various angles and distances, some slow forward flight - my backyard is only about 50feet x 50 feet)


Thanks in advance for the help.

Al
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Old Apr 08, 2002, 10:44 PM
Really?!?
ChrisS's Avatar
Lost ...on the 3rd rock out
Joined Sep 2001
1,243 Posts
O.K., I'm not flying your exact hardware but I'll give it a try...
1.) Yup, they'll do that on a smooth or slick surface, try spooling up on grass or a little bit slower if you can.
2.)A small spark as the system powers up is normal.
3.)Check your speed control docs, my guess would be that your not in the correct stick position when you power the flight pack up.
4.)Again, check your controller docs, my guess is that you have too high an amplifier gain somewhere, at least thats how it works on my actronic, if I get the gain too high it kind of hunts like a gyro.
5.)Use Tri-flow just on the bearings themselves. Put on plastic, oil attracts dust and dirt which will wear your parts out early.
6.)If you know the length you need, a phone call to any of the vendors should answer your question as to what thickness T/R blades they sell. Seems to me most are the same and come with spacers for thicker blade grips.
7.)You kind of answered this yourself. I'd use slow speed for hovering and high speed for aerobatics when you need it.
Chris
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Old Apr 08, 2002, 10:53 PM
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Fred Bronk's Avatar
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Joined Aug 1999
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Spinning during runup? Are you sure you are in heli mode? It should run up smooth and slow enough not to spin.

I have never seen a spark when connecting my packs. It may be the throttle setting as it won't shut down. But it shouldn't power up unless the throttle is at zero either.

I pretty much agree with Chris on the rest.
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Old Apr 08, 2002, 11:09 PM
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Canada, BC, Capital Regional District
Joined Feb 2002
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Chris and Fred, thanks for the comments.

>> 1.) Yup, they'll do that on a smooth or slick surface, try spooling up on grass or a little bit slower if you can.

My grass is too long, so I'm using a 4x4 piece of plywood - very smooth

>> 3.)Check your speed control docs, my guess would be that your not in the correct stick position when you power the flight pack up.

I've tried both zero throttle at starup (normal mode, wait for beeps to signal all ready) and full throttle (speed regulator mode, set to 100% wait for beeps, set to zero, wait for beeps, all is ready). In order for the controller to start, it must see a zero signal from the throttle. Note that at the start of flying and in the middle, it will stop. It's only at the end of the flight.

>> 4.)Again, check your controller docs, my guess is that you have too high an amplifier gain somewhere, at least thats how it works on my actronic, if I get the gain too high it kind of hunts like a gyro.

I have the throttle curve set to 0,78,78,78,78 - is the initial start curve too steep perhaps? (pitch is linear 0-100). This might explain both the problem where it spins at startup and it won't stop, if there isn't enough resolution at the start of the throttle curve.

How do you have your radio set up?


Thanks again,

Al
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Old Apr 08, 2002, 11:20 PM
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Fred Bronk's Avatar
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Joined Aug 1999
22,801 Posts
Not sure what to say about the no stopping at the end of flight?

Are you using a choke in the RX lead? It is a normal item for the Shulze.

Put some bumpers on the skids. You want it to grip a little at least. Your curve sounds fine, but if you want a slower startup try this;

In normal try 0-30-78-78-78. Then as soon as it is up to speed, hit idle 1 and 78 across. Also in normal, set the pitch so you don't have to much neg pitch. Keep about 2 degrees so the blades aren't pushing on dead air during runup.

That really helped my Logo 10. It tried to beat itself on runup till I killed the neg pitch.
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Old Apr 08, 2002, 11:30 PM
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Canada, BC, Capital Regional District
Joined Feb 2002
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I've got a choke on the ESC to receiver cable, so that shouldn't be a problem. My pitch range is -3 to +9 - I'll try the throttle curves you suggested tomorrow.

Thanks,

Al
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Old Apr 08, 2002, 11:30 PM
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St. Mary, Maryland, United States
Joined Dec 1996
8,365 Posts
The spark is normal when you connect the pack, there is a capacitor between the leads to soak up power spikes - when you first connect the battery the cap is not charged and it sucks some power in to do that.

The more cells in the pack the bigger and more noticable the spark. 10-12 cells for instance is barely detectable, 30 cells is alsmost scary
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Old Apr 09, 2002, 12:26 AM
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gpeden's Avatar
Lake Louise, AB, Canada
Joined Feb 2000
3,563 Posts
Hi AL,

Congrats on the first flight!

The spinning during runnup is normal. I use a 3' square of carpet and this really helps because I've been flying on an ice covered parking lot lately.

I don't have much experience using the flight mode switch for throttle yet, but since I use normal mode only for running it up on the ground, I set the throttle curve to 0,0,80,80,80 to ensure more of a dead spot and the pitch curve to 25,25,50,75,100 to have less negative pitch during the first part of the runup. Once the throttle/pitch stick is at mid-position, the heli is running at the lower of the two set head speeds and 0 degrees pitch. I flick the flight mode switch to "1" and there is no transition, but now it is constant speed and ready to lift off.

I don't see a spark from my 24 nicads, but I often hear it.

Cheers!

Glen
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Old Apr 09, 2002, 07:08 AM
Electrics rule
risto's Avatar
Bielefeld, Germany
Joined Jun 2000
437 Posts
> it sounds like more like a real turbo prop aircraft,
> compared to the almost silent Piccolo.
If anyone wants to hear the sound, then download the Light aerobatics video at:
http://www.mh.ttu.ee/risto/rc/logo20/wvideo2.htm#videos

> Futaba GY401 gyro (delay=10, limit=100) with 9253 servo
You should not use any delay with S9253 servo.
Limit value depends on your servo arm length (I have it around 80 with Mikado recommended tail pitch servo arm length).

> Batteries:
Just a comment - Ni-Cd's are better for high load and fast charging than Ni-MH's. They also tolerate abuse much better and won't require so critical maintenance. Although they do weigh more.

> Flight time: 8-9 minutes, Motor temp: 62C,
> Battery Temp: 43C, Ambient: 10C
I am really surprised by your motor temperature. I have the same motor with 20 cells and 9-teeth pinion and after hard 3D flight it is still way less than 60 degrees as I am able to hold my hand on it comfortably (so it has to be less than 45C, otherwise I would feel pain). Battery temperature is OK. As you are getting up to 9 minutes flight time, you cannot be flying 3D also. What pinion are you using?

> 1. When I initially start the motor,
> the helicopter spins around 180-360 degrees
> until the the rotors get up some speed
> (Maybe 500 RPM?). Is this normal?
I can't understand how everybody here says it to be OK. Never seen this to happen myself.
I can put my heli on smooth pavement and spin up and the tail won't move anywhere.
Have you calibrated the center of your tail rotor pitch servo in normal mode (not heading hold)?

> My grass is too long, so I'm using a 4x4 piece of plywood - very smooth
I highly suggest to cut the grass and forget the plywood.

> 2. Whenever I connect the main battery to
> the speed controller (after the receiver
> battery is connected), there is a spark!
> Is this normal?
Yes, this is OK. The Schulze future capacitors will be charged at that point. No way around it really.

> 3. After flying, I land and quite often the
> motor doesn't stop at zero throttle. I need
> adjust the throttle trim down 1 click to stop
> it. Why would this be happening?
You need to adjust the ATV of your transmitter sticks. Using JR radio? Then use 110%.
Schulze future has fixed end-positions, so you cannot reprogram it, instead you have to reprogram the radio.

> 4. In speed regulator mode, the motor surges up
> and down noticeably while starting up. Once it
> reaches full speed it seems very stable.
> Is this normal?
What is the full speed. If it is 500rpm, then yes, if more than 1000rpm, then at least I haven't noticed any floating anymore.

> I have the throttle curve set to 0,78,78,78,78
Use a separate channel for controlling the motor (in regulator mode).
The pitch stick should be only for pitch.

> 5. Lubrication - Is it ok to use silicon spray
> on everything i.e. ball links, swash plate,
> main gear, tail slider?
Should be OK. Note that Mikado explicitly tells not to use grease on the gears though.

> 6. I'd like to get a carbon tail rotor to
> match the main.
I think the original blades are very good.

> 7. Is it better to use higher RPM
> (and thus less pitch) or lower RPM
> to get longer flight times?
I have heard that lower rpm and higher pitch gives longer flight times (never measured this myself). But heli is easier to control at higher rpm!

Risto
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Old Apr 09, 2002, 11:59 AM
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Canada, BC, Capital Regional District
Joined Feb 2002
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Risto,

I'm just hovering and flying about, using a 9 tooth pinion. I have no idea why the motor is that hot, but I can hold onto it for 10 seconds. This doesn't seem too hot to me.

I'll readjust the tail in non-HH mode - that may be part of the problem at startup. I'll also try zero delay to see what effect that has.

Thanks,

Al
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Old Apr 09, 2002, 12:33 PM
Registered User
Mission Viejo, CA, USA
Joined Apr 2000
331 Posts
Hi!

I have a Logo 20 with a Tango motor and a Kontronic controller but I'll have a shot at answering some of your questions:

1) The 'soft start' on my setup is not quite soft enough. The blades will fold and the heli will start the chicken dance! I have to tighten the blades more than I like to avoid this but then I get the spin like you do (well, not 180 or 360!!!, perhaps 45 degrees).

So, instead, after I hook up the main battery I give the main blades a spin by hand and walk over to my flying position. With the blades still spinning I then switch to flight mode 1 and let it spin up. The tail will give a little kick of 5 or 10 degrees but the blades stay extended and the gyro pushes the tail back once things get up to speed.

2) Yup, I can hear it almost every time and see it sometimes too. Hasn't blown up my controller yet in hundreds of flights.

3) Don't have that problem with my setup.

4) On my logo 10 I have a future controler and, yeah, sometimes it sounds like it is 'changing gears' as it spins up. Once it gets up to speed though it is stable.

5) I put some silicone grease on my main gear. Later I removed as much as I could. I never noticed any differnce except for the mess I had to clean up on the inside of the canopy and Logo frames. All the ball links feel free moving so I have never put anything on them.

6) I use 80mm SAB tail rotors which nicely match my 600mm SAB main blades. They did require that I insert a washer so as not to pinch the blade grips.

7) Typically lower RPM means longer flight times. Depends on your pinion choice too. Brushless motors are more efficient at certain RPM's than other RPMS so you may have to experiment with lower pinion tooth counts and higher motor rpms versus higher pinion tooth counts and lower motor rpms.

I have seen a guy with your motor do some hard 3D flying on 24 RC2400 cells and the motor is only 50C -60C when he is done. He drains his battery packs in less than 5 minutes so he is really pulling amps. I believe he is using a 9 tooth pinion and his head speed is 1800+.

Your results seem to indicate that you are not running that motor in its desired efficiency range. Another possiblity is that you are getting really long duration which simply gives the motor more time to accumulate the heat.

Nick
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Old Apr 09, 2002, 10:29 PM
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Canada, BC, Capital Regional District
Joined Feb 2002
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I made some adjustments and tried some of the suggestions (the rain stopped for an hour). I've set the gyro delay to zero, and that made no difference to anything, so I left it there. I also tried the different throttle curves, but the heli still spins around on relatively smooth surfaces at startup. (I've been trying to fly it at round 1500 RPM)

I checked my tail rotor pitch servo. It is set up at neutral with the gyro centered and the pitch slider centered on the tail rotor shaft. This means at neutral the tail has quite a bit of pitch. Is this correct or should the pitch be zero at neutral i.e. should the slider be at the end point when the stick is a neutral?

The engine temperature seems pretty consistent even after 3 flights (about 5 minutes between flights) so I'm not sure that this is a problem.

I tried all three flights in speed regulator mode today. When I run the throttle up there are large variations in speed (similarly at shutdown). Once at speed it seems ok, except during one flight today it seemed to speed up in the middle of the flight. Since I have a flat throttle curve this seems odd. It might be a bad controller, but that seems unlikely since the rest of it seems to work fine. I'm not sure what to do about this.

At this point my only significant concerns are the spinng around at startup and the surging in speed regulator mode on the speed controller. I'll try it on the grass tomorrow (weather permitting) and also our brick patio (it might be a little to close to the house!). Other than that everything seems to work just great.

I tried a few high speed pirouettes today - not bad, but they seemed much smoother and easier in the simulator!

Thanks for the help.

Al
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Old Apr 09, 2002, 11:40 PM
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gpeden's Avatar
Lake Louise, AB, Canada
Joined Feb 2000
3,563 Posts
Hi Al,

"I checked my tail rotor pitch servo. It is set up at neutral with the gyro centered and the pitch slider centered on the tail rotor shaft. This means at neutral the tail has quite a bit of pitch. Is this correct or should the pitch be zero at neutral i.e. should the slider be at the end point when the stick is a neutral?"

I think that mine is close to what you have. With the T/R hub flush with the end of the shaft, I have the T/R servo arm vertical at the same time the T/R lever arm (that has ball link ball) is perpendicular to the boom. IOW, the servo arm and the lever arm are both perpendicular to the pushrod at the same time. Always done it, always worked

Cheers!

Glen
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Old Apr 10, 2002, 12:06 AM
ehx
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Northern Minnesota
Joined Oct 2001
444 Posts
Schulze controller startup speed programmable?

>1. When I initially start the motor, the helicopter spins around 180-360 degrees until the the rotors get up some
speed (Maybe 500 RPM?). Is this normal?

I had the same thing happen with my Plettenberg 300/25/A3 + Future 35ho. The first few flights I had it on Rotopod training gear so I didn't worry too much about it, but it did seem to have too much torque. Takeoffs with the skids on asphalt resulted in 360s. There was definitely too much torque. I only did this a few times as I just wanted to make sure the motor and controller worked. Does anyone know if the startup speed can be changed with Schulze's software? Maybe programming the controller when the helicopter is on a smooth surface causes problems?

I'm flying my Logo 20 with a Tango 45-08 and a Kontronik Beat controller now. The spinup with the Beat is so gentle that it probably wouldn't spin the chopper even if it was on ice!

I got about a dozen flights in with my Logo over the last couple of days. This was the first week in 5 months with the temperature much above freezing - at least a couple days were. It's been so long I forgot how nice it is to fly in warm weather.
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Old Apr 10, 2002, 12:27 AM
1.21 Gigawatts!
Steph280's Avatar
Irvine, CA, USA
Joined Oct 2000
7,531 Posts
That startup spin is normal. Think about it. Your tail blades need to pick up enough speed to have any effect compensating the main rotor torque. The only thing that's preventing the heli from spinning during this startup phase is the friction between landing skids and ground. That's why you don't see many model helis flying off of water with pantoons.
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