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Thread: Current favorite fixed wing pusher for FPV

  1. #11
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    Quote Originally Posted by parajared View Post
    1)operating voltage: Your operating voltage has nothing to do with the wattage a given battery has potential to give. Configuring in series, configuring in parallel it doesn't change the output value
    You could use a 10ah 3s battery and you could use a 5ah 6s battery and you would have the exact same max wattage potential.
    2)15% rule: you won’t get the full ah rating out of your battery after you exceed about 15% of that max wattage number I mentioned. I stick 3s 10.4ah 10c batteries in my mini-talon because of this. Mathematically/technically this is a battery capable of 104amps discharge or 1154 watts. This is a good number for me because 1154 x 15% = 173 watts.
    That means if I start to exceed 173 watts of draw out my 10.4 ah battery I have more like a 9 ah battery. Most of those watts going into the forward momentum of the plane but wattage also going into making the battery warm.
    Lion is only like 2c dude, mini-t requires 70-100 watts, a 666 watthour Satan battery is too big or alternately a 50 watt mini-talon would kinda suck IMO.
    3) you can’t exceed more than about 140 grams or so on the tail of a mini-t. Most, if not all 6s motors within the right KV weigh more than that.



    I used stuff called “Instamorph” to shape a nose motor holder on mine. It worked ok.


    It looked really awesome in the air, the guys at the field seemed to really get a kick out of watching that thing fly. Kinda flew like crap though to be honest, issues with tip stalls and the wings would turn into wacky waving flappy wings in air turbulence, also something of awe but for entirely different reasons.

    I took my Eagle Tree Vector out of that Talon I crashed and put it in my DG808. I got everything up and working and had maybe 15-20 flights on her getting everything dialed in and feeling comfortable with it. My last flight my PSU from the crashed Talon flexed a little, broke contact turned off and turned back on mid-flight. During Eagle-tree’s boot up process I couldn’t control the aircraft and it spiraled in and turned into a massive smoldering (literally) pile of toothpicks. Fortunately I was able to stamp out the fire before it got out of hand. Post-mortem on the plane indicated that the PSU (likely damaged by my Talon crash) seemed to be the problem. I have a DVR video of the crash; my youtube name is parajared fpv.



    I never got to use it for endurance flight like I had hoped for. At 3750 grams AUW I was getting a sink rate of about 150fpm and motor off cruise speed of about 26mph which made it start to look promising. It thermalled like a dump truck though and flew right awful under motor power so not feasible for as a glider or a motor ship in my opinion. Made for a good “spectacle ship” though. It was fun to fly around for sure even if not necessarily an airplane that flew with performance.
    1. I didn't say wattage I said Amperage. Li-Ion has a low C rating. C rating is a amp draw per battery capacity value. If you lower your amp draw you are then lowering your C rating ratio. Higher voltage is better for lower amp draw.
    And you are incorrect. Higher voltage does lower your wattage. Amps cause heat. Heat = energy loss/lower power. Yes it's "insignificant" but since were splitting hairs your statement isn't exactly correct.
    Beyond that lower kV motors allow for more torque. More torque means larger props. Larger props mean less RPM. Less RPM means less angular and linear velocity. Less velocity means less drag making your plane more efficient.
    So 6S on many levels does create less wattage. If you use the very simplified V*I=W yea you get same wattage out put that effects your C rating. But it's just not correct.

    2. I understand battery curves and how they decrease rapidly then level off then tank at the end again. I've plotted them and tested this.

    Unfortunate to hear about the DG808. It looked like a budget big bird. Seems like that's what it is. At least they aren't very expensive. The big foamies are hard to beat but getting ones that are 4m is kind of a push.
    Most of my flying is not hot rodding around. I usually try to get to cool spots and get nice footage. It seems then my DG808 may just sit in the box and not get built for a while.

    I do have a phoenix evolution that I might try to make a cheap thing out of but I'm not really digging this plane as something to spend too much time digging into.
    sum ting wong
    WI to low
    BANG DING OW -chatch

    Sounds like a typical RcLab1 maiden flight to me :D -ssassen

    Whatever. This forum sucks. -SENTRY

  2. #12
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    Amperage isn't a function of heat, amperage down the wrong gauge wire is heat. Amperage is a penalty of weight, you need more copper fill to efficiently flow higher amperage.

    In any case it sounds like you are after about a max rpm of 13,000 or so. That would be a ~600kv motor on 6s. 6s 600kv motors aren't made to spin 9 inch propellers they are made to spin 14 plus inch propellers. You need big magnets to provide the repulsive gauss needed to generate the "torque" you are referring to. You would be hefting a lot of magnet weight at no additional gain. You only need so much magnet to spin a 9 incher.

    Why not use a 14 inch propeller on a mini-t you ask?
    Well Billy,
    you need enough propeller diameter to overcome the drag of the aircraft and then your efficiency curve goes flat. Your efficiency doesn't go up past the "bubble", it goes down, you aren't going to gain efficiency by over propping.

    Motor KV is an efficiency myth.
    I recommend if you do build a mini-talon that you target 18,000 to 20,000 rpm. You will have a mini-t beefy enough to fly fast and fun and I know for a fact that it will fly at the exact same cruise efficiency as a 13,000 build.

  3. #13
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    ... of course this is coming from a guy who runs his mini-talon at over 55,000 rpm
    Last edited by parajared; 21st February 2018 at 10:35 PM. Reason: add the word "over" in, it will sound cooler.

  4. #14
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    It's not new, and certainly not popular at all (I think I'm the only one in the world flying it) but I really love my VAS Pegasus. It flies great (a great sightseeing FPV plane) and of course flight time is everything about how you set it up. But no problem to get an hour at that speed. No dome though, but I've never liked them anyway. Dirt, scratches, sun glare etc.

    Beware though it's a bit of a tricky build to get squared up and true, but Alex says it doesn't matter it will fly well regardless. Mine is perfect but you have to be careful to get it that way. Easy to end up with parts of the plane pointing in 5 different directions if you just slap it together.

    Also really like my Caipi V2. Very cool wing. It's only 36.5" wing span but it can handle a 4sx6000 lipo! Unusual to say the least. . But at cruise it's real stable. Not much wag at all for a wing. Certain flight conditions it's more noticeable. But in a straight slow cruise it's real stable no wag.

    But the Pegasus flies on a rail. Canard plane too! So cool (to me anyway, apparently no one else in the world lol).

  5. #15
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    I have a Pegasus that I started building last year and never got around to finish. Hopefully I will get some cleaning done in my workshop so I can pick up where I left off but I have so many damn builds going on at the same time. It is such a cool looking plane though.

  6. #16
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    Quote Originally Posted by edin508 View Post
    I have a Pegasus that I started building last year and never got around to finish. Hopefully I will get some cleaning done in my workshop so I can pick up where I left off but I have so many damn builds going on at the same time. It is such a cool looking plane though.

    You need to finish the pegasus. It's well worth it imo. Over in the VAS section Pegasus thread I have some decent tips that may help in your build and also some setup stuff that I would have loved to have before maiden. Good luck with it!

  7. #17
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    My favorite is the " Plain Jane" Radian glider. But as far as pusher prop then it would be the Skywalker.

    Last edited by canadianstarman; 1st March 2018 at 05:46 PM.
    If at first an idea doesn't sound absurd, then there is no hope for it. - by Albert Einstein

  8. #18
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    Quote Originally Posted by canadianstarman View Post
    My favorite is the " Plain Jane" Radian glider. But as far as pusher prop then it would be the Skywalker.

    Love the Radian pro and you can fly that forever. But I've never set mine up for FPV

  9. #19
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    I use to have a Radian Pro FPV set-up but it's flight times weren't that impressive. It's just too heavy due to the extra servos and control surfaces .
    If at first an idea doesn't sound absurd, then there is no hope for it. - by Albert Einstein

  10. #20
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    The ZOHD Nano Talon is easy to transport, perfectly designed for FPV, and will fly over an hour on stock setup with 3S 4200mah 20700 size Li Ion packs. I have flown mine over 5 miles out on 5.8GHz video, iNav, and Crossfire for control, but there's room to tuck a 1.3GHz Singularity antenna inside if you want. it is small and light, so will rock some in higher winds, but handles it just fine. Happily cruises about 30MPH at around 4A, full throttle is maybe 10A.

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