Page 2 of 7 FirstFirst 123456 ... LastLast
Results 11 to 20 of 63

Thread: Surgery on a fixed-pitch flybar...

  1. #11
    Join Date
    Feb 2008
    Location
    East Sussex, England
    Posts
    5,248

    Default

    Adam, I don't suppose you know what radio protocol the V912 uses do you? The V912 BNF is silly cheap but I would like to know if I can get a compatible module first

    Edit: not to worry, found a thread on the OpenRC forum, it's FlySky and the modules are just over £10
    Last edited by norty303; 04-07-2014 at 14:53.
    Frikkin Lasers
    http://www.frikkinlasers.co.uk

    You are using Bonetti's defense against me, ah?

    I thought it fitting, considering the rocky terrain.

  2. #12
    Join Date
    Jan 2006
    Location
    Charleston, SC
    Posts
    2,147,489,446

    Default

    Hi Adam;

    You're right, the V911 and V912 both use Flysky.

    The V912 will probably run just fine on the 2S 1000maA LiPos you have, provided they will fit in the bird. Look at the picture I posted above and see if it looks about right. (The battery is in the nose just below the flight control board.) It's a folded, square-ish package.

    Note what I said earlier about the 912 being overly-stable though. If you don't modify the flybar system, you don't want to take it outside in any kind of wind, and I'd never let it get above 50 ft no matter what. Also, even during controlled flight, you need to be thinking ahead, since it won't exactly stop on a dime.

    If you remove some of the weight from the flybar, then it becomes much more maneuverable, and the stability really doesn't suffer until you get down to nearly zero weight on the flybar. I think a happy medium is probably 3-4 grams for a beginner, and 1-2 grams for a more experienced pilot. But 6 grams on each end is just too much. (that's what it comes with stock though - 6 grams)

    I found a partial table of compatible radios and protocols on-line. I've uploaded it to my gallery; here's the link: http://photonlexicon.com/gallery/v/u...able_xlsx.html (Just click on "download the file" to get it.) It's in Excel format...

    Adam

    PS: Here's part of my collection (2 others not shown), and yes I'm an idiot in that I have a separate controller for each bird I own.



    The 912 is in the upper-right, obviously. More pics in my gallery!

  3. #13
    Join Date
    Nov 2008
    Location
    Cleveland Ohio
    Posts
    2,599

    Default

    I have the same chopper plus about five others. Shorten the bar to bring in the weights and it will get more unstable. Get threaded rod and make your own flybar and use nuts on it to move in and out.

    Get a variable pitch 6 ch if you want real fun. The FP's are a bummer. I love the v911. nearly indestructibly but no acrobatics. The v912 flies like a truck.

    I have some flybarless ones and they fly real well but you need to be able to fly a proportional and not FP. I have a flybarless FP but it is boring. My horizon hobby sr is a good bird. I have a spectrum transmitter and just get bnf.

  4. #14
    Join Date
    Feb 2008
    Location
    East Sussex, England
    Posts
    5,248

    Default

    Well I figured at £27 each, and £8 for the spares pack I could get a couple of V912 and a spares pack and then I have a load of spares and 3 flybars to experiment with. I also like the V913 and for £50 it seems like a good deal.
    And all cheaper than a couple of diodes, collimators and some correction optics
    Frikkin Lasers
    http://www.frikkinlasers.co.uk

    You are using Bonetti's defense against me, ah?

    I thought it fitting, considering the rocky terrain.

  5. #15
    Join Date
    Feb 2008
    Location
    East Sussex, England
    Posts
    5,248

    Default

    Get a variable pitch 6 ch if you want real fun.
    I've been wondering about the Tx setup for a collective pitch heli.

    On the electric soarers we tend to keep the flaps/spoilers/crow on the throttle stick, with motor control on a switch (its all or nothing when you need it - climb as fast as possible, then glide as long as possible).

    On the collective pitch helis do you put the collective on the throttle stick, (as it more of a primary control), and motor speed on a slider/variable pot?

    What is the 6th channel for btw?
    Frikkin Lasers
    http://www.frikkinlasers.co.uk

    You are using Bonetti's defense against me, ah?

    I thought it fitting, considering the rocky terrain.

  6. #16
    Join Date
    Jul 2007
    Location
    Knoxville, TN, USA
    Posts
    3,154

    Default

    Quote Originally Posted by norty303 View Post
    I've been wondering about the Tx setup for a collective pitch heli.

    On the electric soarers we tend to keep the flaps/spoilers/crow on the throttle stick, with motor control on a switch (its all or nothing when you need it - climb as fast as possible, then glide as long as possible).

    On the collective pitch helis do you put the collective on the throttle stick, (as it more of a primary control), and motor speed on a slider/variable pot?

    What is the 6th channel for btw?
    Most heli flyers in the US are flying Mode 2

    Left Stick:
    Vertical axis - Throttle + Collective (2 channels combined), with the ability to lockout the throttle with a Throttle Hold feature
    Horizontal axis - rudder (tail rotor)

    Right stick:
    Vertical axis - elevator (fore/aft cyclic)
    Horizontal axis - ailerons (lateral cyclic)

    6th channel is for gyro gain & mode control.

    Once you get into collective pitch (CP) helicopters, you really need a programmable radio that has features specifically made for helicopters.
    (Gyro, pitch & throttle curves are a pretty big deal once you get into CP copters ~
    properly programming these curves can have a huge impact on the copter's performance and handling!)

    I'm betting your 16-channel transmitter already has helicopter programmability!

    That RC Helicopter Fun web site I linked to in my earlier post includes a lot of information about the different helicopter controls & radio programming - and just about everything else you can think of where RC helicopters are concerned (especially electrics!).

    Randy
    Last edited by Stuka; 04-08-2014 at 06:19.
    RR

    Metrologic HeNe 3.3mw Modulated laser, 2 Radio Shack motors, and a broken mirror.
    1979.
    Sweet.....

  7. #17
    Join Date
    Feb 2008
    Location
    East Sussex, England
    Posts
    5,248

    Default

    The Taranis uses an open source firmware called OpenTx which was originally designed for the Turnigy 9X transmitters, and then FrSky released the Taranis, designed to specifically support the OpenTx firmware (although it comes with its own simpler version out of the box).

    It has some standard templates (including helis and multi rotor) but the real beauty (for me and a lot of people) is the absolute control over everything! I like it because I'm a programmer anyway, lots of people don't like it for the same reason

    I fly mode 2 as well, interesting to hear that you use a motor/collective mix on the throttle. I'm guessing you mix different amounts of each (less motor and more collective for a given stick movement) to maintain a more constant rotation speed? Or do you just use the hold a lot?

    OpenTx also supports throws up to 125%, so I wonder if that might help with Buffos lack of elevator control on the V912?
    Frikkin Lasers
    http://www.frikkinlasers.co.uk

    You are using Bonetti's defense against me, ah?

    I thought it fitting, considering the rocky terrain.

  8. #18
    Join Date
    Jul 2007
    Location
    Knoxville, TN, USA
    Posts
    3,154

    Default

    I've met a couple of folks here in Hunstville that are tinkering with Taranis _
    pretty cool that it offers cross-platform support for the different 2.4gHz protocols floating around!
    That said, this is definitely a "Futaba town", which is what is flown by a most of the "serious" RC copter pilots around here.
    Probably doesn't hurt that Futaba has a development facility located here, and a factory rep that sponsors events & frequently visits the local flying field.

    I fly primarily Spektrum, so I guess I'm only semi-serious...

    Throttle hold is primarily a feature to enable autorotations ~
    It holds the throttle at idle, while maintaining full collective control via the throttle stick.

    Throttle / pitch curves are somewhat of a science / art in and of themselves, and can vary greatly between the type & power-class of helicopter, and the "flight mode" it's being flown in. Generally, throttle & pitch curves are setup so they both increase/decrease exponentially, since the goal is to maintain RPM (headspeed) as the collective load increases / decreases. That's part of the reason CP copters are generally both more aerobatic & in many ways, more stable than fixed pitch, since the RPM stays relatively constant, regardless of collective load. Also, with all but "micro" CP copters, the tail rotor is generally belt or torque tube driven by the main gear, so as with the main rotor, speed is relatively constant.

    Just like real (1:1 scale) helicopters!

    Since the "elevator" control of a fixed-pitch copter is based purely on RPM, increasing throw might or might not have an impact.
    Lack of elevator authority may actually be because the motor/ESC combo and battery for that helicopter are reaching their max performance and starting to "sag" on the top end...
    Last edited by Stuka; 04-08-2014 at 05:40.
    RR

    Metrologic HeNe 3.3mw Modulated laser, 2 Radio Shack motors, and a broken mirror.
    1979.
    Sweet.....

  9. #19
    Join Date
    Feb 2008
    Location
    East Sussex, England
    Posts
    5,248

    Default

    Ah, thats all starting to make logical sense.
    So, in the same way as CP flyers have a black art of throttle/pitch curves, I guess the FP flyers also have a certain amount of yaw/rudder mix in to the throttle stick, to counteract the increased/decreased yawing motion of the different rotor speed?

    Since the "elevator" control of a fixed-pitch copter is based purely on RPM, increasing throw might or might not have an impact.
    Can you explain that for me as I may have it all wrong?
    I thought the 'elevator' on a single rotor FP heli was via the back/forth tilt to the swash plate (rather than a vertical tail rotor like on the coaxial birds), so forward/down elevator on the stick causes the rear blade to have more pitch, so speed of rotation AND angle of attack (i.e. servo throw) all influence the effectiveness of the control.

    Or do I have it wrong and the swash on a FP bird just tilts back and forth the whole rotor, in which case, servo throw is still a factor?
    Frikkin Lasers
    http://www.frikkinlasers.co.uk

    You are using Bonetti's defense against me, ah?

    I thought it fitting, considering the rocky terrain.

  10. #20
    Join Date
    Jan 2006
    Location
    Charleston, SC
    Posts
    2,147,489,446

    Smile

    Quote Originally Posted by Stuka View Post
    Most heli flyers in the US are flying Mode 2
    For those that may not realize it, this is an important fact to stress. When you order from Banggood, if you are ordering a ready-to-fly bird (one that comes with a controller), make *certain* you specify Mode 2 (left-hand throttle). Otherwise you'll get a mode-1 transmitter (which seems to be more popular in Asia for some reason), and it will be very difficult to use.

    6th channel is for gyro gain & mode control.
    To expand on this, typically you only need a 6 channel radio if you're flying collective pitch. And in that case, you also need a pair of toggle switches on the controller. One is your ground safety switch (prevents the rotors from turning regardless of the throttle position for safe start-up) and the other is your throttle-up switch. Normally you spin the rotors up to half-speed and then flip the throttle-up switch to bring the rotor speed up to maximum.

    However, some collective pitch helicopters will allow you to fly in a pseudo-fixed-pitch mode with the throttle up switch off. The left stick then acts as both throttle control and pitch control, but it normally only gives you positive pitch. This allows you to get the bird into the air and in a stable hover before you speed the rotor up to maximum. (That's the way my Nasa701 for the Wasp Nano is set up.) Not really sure that it helps all that much though. (Damned thing is still too squirrely to fly, even with the gyro gain set really high. Even Chris had trouble with it at FLEM...)

    Gyro, pitch & throttle curves are a pretty big deal once you get into CP copters
    Amen to that, brother!

    Quote Originally Posted by kecked View Post
    The v912 flies like a truck.
    Couldn't have said it better myself. Though admittedly if you lighten the weights on the flybar, it does become more maneuverable. Still nothing like the little V911 though!

    Shorten the bar to bring in the weights and it will get more unstable.
    Yeah, I wouldn't try reducing the length of the bar. But reducing the weight at the tips seems to work well.

    Get a variable pitch 6 ch if you want real fun. The FP's are a bummer.
    About the only thing I can't do with my smaller fixed-pitch bird is fly upside down or do extreme acrobatics. But to be honest, I'm nowhere near good enough to fly inverted, let alone try to do anything more advanced anyway.

    I love the v911. nearly indestructible
    I agree completely. About the only thing wrong with the V911 is the short flight time.

    Quote Originally Posted by norty303 View Post
    I fly mode 2 as well, interesting to hear that you use a motor/collective mix on the throttle.
    That's only on a collective pitch bird when you don't have the throttle-up switch engaged. Once you hit throttle-up, the left stick is your pitch control only (just like in a real helicopter, with positive and negative pitch available), and the rotor speed is more or less constant (which is to say wide-ass open!)

    OpenTx also supports throws up to 125%, so I wonder if that might help with Buffos lack of elevator control on the V912?
    It might help a bit, but I'm not going to spend several hundred bucks on a new radio to remedy the shortcomings of a heli that I only spent $70 on.

    Truthfully, my next purchase will probably be the Skyartec Wasp X3V. It's a 250 series flybarless collective-pitch bird with an all-metal rotor head design and a shaft-driven variable-pitch tail rotor. Best thing is that it will work with my Skyartec Nasa701 programmable transmitter, so for once I won't have to buy a new radio! But it's $170 just for the BNF version of the bird, so I'm on the fence...

    Quote Originally Posted by Stuka View Post
    Since the "elevator" control of a fixed-pitch copter is based purely on RPM, increasing throw might or might not have an impact.
    Umm... I think you've got your wires crossed, Randy. Elevator control on a helicopter is accomplished with cyclic pitch control, just like roll control is. Neither one is really affected by rotor RPM, provided you have enough RPM to remain airborne of course. I think you're confusing the airplane term "elevator" with "lift" on a helicopter, as lift is definitely a factor of RPM on a fixed-pitch bird, but the elevator on an airplane is a control surface on the tail that causes the airframe to pitch up or down.

    Having greater throw on the pitch servo to the swash-plate would definitely give me more control, although I'd still be fighting the over-size flybar. It's just that I don't feel like spending a lot of money on a new transmitter when it would be cheaper to just buy a different bird. The V912 was really cheap, remember.

    Adam

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •