RE: Multiplex Magister RTF  
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    • All Forums >> Electric Aircraft Universe >> Electric Training >> RE: Multiplex Magister RTF
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    RE: Multiplex Magister RTF - 12/8/2005 10:18:50 PM   
    TManiaci



    Posts: 1489
    Joined: 10/7/2004
    From: Temecula, CA, USA
    Status: offline     		Great Greg!

    So, with some effort, we could easily be under 60 oz's with our build. That should work out pretty good then. Well over 50% thrust to weight ratio is easy to acheve then and safe to fly. I am one to love "more-power", and rarely build with less that 180% thrust-to-weight ratio for 3D.

    I see the photos apparently indicate full-size servos. Maybe HS-55 servos will work the tailfeathers, with a HS-425BB on the ailerons, maybe get us even lighter... What servos are you flying? On a trainer, not a lot of torque needed, small throws with good mechanical advantage.... hmmm. How do you feel about servo torque requirements?




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    TMan

    (in reply to Greg Covey)
           Post #: 126

    RE: Multiplex Magister RTF - 12/9/2005 1:07:02 AM   
    Greg Covey



    Posts: 4450
    Joined: 5/24/2003
    From: Rochester, NY, USA
    Status: offline     		My Magister came with the stock Hitec Laser 4 radio system already installed. They look like standard size servos so I would recommend HS-81s as the lightest choice.



    < Message edited by Greg Covey -- 12/9/2005 5:31:59 PM >

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    Visit my Web Hangar at www.gregcovey.com/rc.htm

    (in reply to TManiaci)
           Post #: 127

    RE: Multiplex Magister RTF - 12/9/2005 3:57:33 AM   
    TManiaci



    Posts: 1489
    Joined: 10/7/2004
    From: Temecula, CA, USA
    Status: offline     		Yea, I was just thinking HS-81 would be a good choice too. Fast, strong and light.

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    TMan

    (in reply to Greg Covey)
           Post #: 128

    RE: Multiplex Magister RTF - 12/18/2005 3:11:00 PM   
    carlrich


     

    Posts: 171
    Joined: 1/24/2005
    From: cincinnati, OH, USA
    Status: offline     		Has anyone else messed up the magister gearbox and plastic wing retainers? Bent prop shaft and snapped retainers. Wing and fuselage took a nose in rather hard with VERY minor damage. I expected a pile of loose foam based on sound of crash but it held up very well.

    Where can one buy just the gearbox and wing retainer straps?

    Until I get these I will attempt flight with a gearbox from the great planes Super Sportster EP. The spur gear seems to fit the motor pinion fine. ratio now 2.25:1 so I'll need a prop with less pitch I'm guessing. Maybe a 12x6????
    Carl

    (in reply to TManiaci)
           Post #: 129

    RE: Multiplex Magister RTF - 12/18/2005 3:25:42 PM   
    Greg Covey



    Posts: 4450
    Joined: 5/24/2003
    From: Rochester, NY, USA
    Status: offline     		Carl,

    Sometimes Hobby Lobby sells parts for their planes without advertising it on their Web site. It would be worth calling them.

    Also, Hobby Lobby does sell gearboxes for the Speed 680 (aka Speed 700) motor but the prices are higher than just buying a new complete replacement power system at Tower Hobbies.

    Hobby Lobby Speed 700 Gearboxes

    Magister Power System at Tower Hobbies


    _____________________________

    Visit my Web Hangar at www.gregcovey.com/rc.htm

    (in reply to carlrich)
           Post #: 130

    RE: Multiplex Magister RTF - 12/18/2005 3:30:24 PM   
    TManiaci



    Posts: 1489
    Joined: 10/7/2004
    From: Temecula, CA, USA
    Status: offline     		We have my father-in-law's Magister all wrapped under the tree, waiting for the big day. Can't wait to put this thing together and go fly it! Got him some HS-81's too, so we're all set with all the hardware. Also picked up two 3S 1800 mAH 12C lipo's for it... keeping it light. Should be amazing.

    _____________________________

    TMan

    (in reply to Greg Covey)
           Post #: 131

    RE: Multiplex Magister RTF - 12/31/2005 5:25:26 PM   
    TManiaci



    Posts: 1489
    Joined: 10/7/2004
    From: Temecula, CA, USA
    Status: offline     		Well, finished the build on my Father-in-law's Magister over the last few days since Christmas. Used HS-81 Servos, and made servo plates from 3/32" ply glued in with foam-safe CA (see photos).

    Drum roll please..... the AUW came in at 53 oz's! Well under the 60 oz target weight... nice . All that's left is to add decals.

    Setup:
    AXI 2808/24
    CC Phoenix 35
    Dymond Modelsports 3S HD 2100 mAH 12C Lipo
    JR UL610 Rx
    APC 11x5.5E

    This rig will make 275 watts @ ~25 amps, and pulls 45 oz's thrust. I'll retest that and verify, get more precise numbers when I get time. Should fly pretty well with 85% thrust to weight ratio. CG came in dead on the book recommendation without special arrangements, everything in stock locations. The lighter servos rear seems to offset the light motor up front. Sweet!

    This is a very nicely engineered chuck of foam, I am impressed. Everything fit to gether very nicely. I only made a few minor mods in the build. I think some Dubro Ultralite wheels will kill another once or so. I was able to get some great throws on the controls too, and these HS-81's are very quick and seem to have plenty of power to slam the surfaces to the stops. Should fly well, can't wait to maiden.

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    < Message edited by TManiaci -- 1/3/2006 3:53:22 AM >

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    TMan

    (in reply to TManiaci)
           Post #: 132

    RE: Multiplex Magister RTF - 1/6/2006 12:51:41 AM   
    carlrich


     

    Posts: 171
    Joined: 1/24/2005
    From: cincinnati, OH, USA
    Status: offline     		Tman, how did you enjoy flying the Magister? I hope all went well. I've found mine very easy to fly other than the one time I loaded too many lipos in the very front area messing up my CG and attempted inverted flight. Face plant. Very little damage, repaired very easily and flies as easily as ever now. I'm working on not bouncing when I land and am getting pretty good.

    Carl

    (in reply to TManiaci)
           Post #: 133

    RE: Multiplex Magister RTF - 1/6/2006 12:55:31 AM   
    TManiaci



    Posts: 1489
    Joined: 10/7/2004
    From: Temecula, CA, USA
    Status: offline     		Well Carl, we have not had opportunity to fly it yet. The weather just sucked until yesterday, and nowthe day is consumed with that nagging obligation I call work. Out of town this weekend, so not a shot then, and knee surgery next week will likely kill any chances the followign weekend. Ugh! I'm gonna find a moment, just not sure when...

    Were you surprised we managed to get her so light? 53 oz is pretty amazing I think...

    < Message edited by TManiaci -- 1/6/2006 12:57:06 AM >

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    TMan

    (in reply to carlrich)
           Post #: 134

    RE: Multiplex Magister RTF - 1/6/2006 11:51:22 AM   
    carlrich


     

    Posts: 171
    Joined: 1/24/2005
    From: cincinnati, OH, USA
    Status: offline     		Yeah, that is light. Mine came in at just a hair over 5 lbs. like 81 oz. as it came stock in the RTF package with the battery. It climbed at an excellent rate with plenty of power. I bought another 8 cell pack with 3600mah capacity to give more flight time. I go back and forth with lipos as I have installed an esc that will work with either. My only complaint is that when the motor dies you are totally finished flying and better be on the ground or set up and on final approach or your going down somewhere you may not want to. My other models kill the motor but you can bring it back on for say 20 seconds. Not this one. So keep that in mind.

    Carl

    (in reply to TManiaci)
           Post #: 135

    RE: Multiplex Magister RTF - 1/11/2006 1:27:11 AM   
    javiergarzab


     

    Posts: 42
    Joined: 3/31/2005
    From: CuernavacaMorelos, MEXICO
    Status: offline     		I really appreciate you guys giving us all those tips, hints and sharing your experiences. They have been really valuable.

    I got my magister one month ago but got tired of the stock engine. It's a capable engine but prefered to give a Hacker A30-10XL the chance. Wow!. I got a great climb rate!! Now I was confident enough to do some more acrobatics. The full setup includes a 12x6 APC propeller, E-flite 40 Amp brushless ESC and Tanic 3s1P 2500 mah Lipo.

    I'm still having problems at identifying the flight time of this setup. I Just tried it last weekend, but never exceded 5 minutes of flight time... I'd rather be on the safe side. Anyone can estimate my flight time? Or give any recomendations to increase it?

    Regards

    Javier

    (in reply to carlrich)
           Post #: 136

    RE: Multiplex Magister RTF - 1/11/2006 1:41:17 AM   
    TManiaci



    Posts: 1489
    Joined: 10/7/2004
    From: Temecula, CA, USA
    Status: offline     		Javier,

    That is easy to do.... but, you need a Wattmeter to gather the information.

    If you have one, you can connect it in series with your charger after a timed flight. Then, when it's charged, read the mAH on the display that was put into the battery.

    Now it's math... you have 2500 mAH to use, and you flew for 5 minutes, and let's say your charge put in 800 mAH. Assume you get 100% of your mAH rating (not real, but close).

    So, you are using (on average) 800 mAH / 5 min. = 160 mAH per minute.

    Now assume you get all your battery use to LVC, 2500 mAH / 160 mAH per min. = 15.6 minutes.

    Now, to be conservative, take 80% of that = 12.5 minutes. Set your timer there and you should be fine. If you fly really hard, be a little more careful. You develop a feel for it, and you should stay up high and over your landing area when are close to your estimated time just in case.

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    TMan

    (in reply to javiergarzab)
           Post #: 137

    RE: Multiplex Magister RTF - 1/11/2006 1:46:15 AM   
    carlrich


     

    Posts: 171
    Joined: 1/24/2005
    From: cincinnati, OH, USA
    Status: offline     		You have 2500mah which is 2.5Ah x 60 is 150Aminutes. If you put a watt meter between your battery and esc you will know the amps used at different levels of throttle. If you want to be really conservative you could start with max amps used at full throttle. If this number is say 25 amps. Then dividing 150Aminutes by the number of amps drawn / 25A you get 6 minutes of flight at full throttle. You would actually get a bit more flying time as a static test of amps will be higher compared to a plane that is already moving and the motor is not working so hard to turn the prop. You don't want to run your lipo totally dead so stay conservative.

    Alternately you could charge the battery fresh. Fly for 5 minutes. Recharge the battery on a charger that shows the number of mah going into the battery (Triton charger) or use any charger and put a watt meter between the charger and the battery. If in 5 minutes of flight your battery requires say 1250mah to be recharged in full then you used half of the 2500mah available and could have flown for roughly twice as long (10 minutes).

    I like the magister in stock form so it must be a hoot with brushless. I have flown the stock motor with a esc that allows lipo on a 3 cell lipo and it's great.

    Carl

    (in reply to javiergarzab)
           Post #: 138

    RE: Multiplex Magister RTF - 1/11/2006 5:48:36 PM   
    javiergarzab


     

    Posts: 42
    Joined: 3/31/2005
    From: CuernavacaMorelos, MEXICO
    Status: offline     		Thank you. I'll give a look at my charger on my next flight and will try carlrich second option. My charger has a display an it effectively shows how many mah's are beeing delivered. Unfortunately I have to wait two more weeks to give it a try because I'm going oyt on a trip and can't take the magister with me, but I'll let you know my results ASAP.

    Carl, you should really try brushless on it, or if you want to feel something closer to how it performs (just on the climbing rate) then install an APC 12x6 SF. It really pulls!, we tried it and now my other friends have ordered them! (We fly at 4900 ft above sea level. I don't know how well they'll perform at lower heights)

    Javier

    (in reply to carlrich)