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Old Jan 28, 2010, 07:36 AM
Any excuse to fly
United States, FL, Clearwater
Joined Apr 2008
556 Posts
Discussion
?? How heavy is your plane ?? Diet parts...

I read alot and get lots of ideas from others builds on here.

I'm in the middle of building a Radian for my next FPV plane, I'm soldering wires to avoid thet weight plugs etc and running a 2250 lipo and a 900 for vtx

What does your plane weigh and what tricks do you use to put it on a Diet?
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Old Jan 28, 2010, 07:38 AM
Mums the word.
man2000me's Avatar
St.Augustine, FL
Joined Sep 2009
2,061 Posts
Balance plane so no "counter weight" is used for COG.
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Old Jan 28, 2010, 07:52 AM
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Netherlands, NH, Edam
Joined Jul 2004
5,535 Posts
What he said, and trim everything down to minimum required length, wires, etc.

Cheers,

Sander.
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Old Jan 28, 2010, 08:14 AM
Any excuse to fly
United States, FL, Clearwater
Joined Apr 2008
556 Posts
I have not added extra weight, I lay the parts out to balance it.
Just thought this would be a good thread to compare weights of you plane and trick to loose weight for future builders.
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Old Jan 28, 2010, 08:49 AM
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Joined Aug 2009
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my current plane is.. 85gr all up (but its also 193mm long.)

but i plan to make a bigger/heavier one (not above the 1kg mark) when i'm decided on what kind of flying wing i'd like.

things i found however heavy and replacable usually:

- all kind of plugs. i solder most stuff and put plugs only on what is necessary for easy manipulation

- camera casing, usually made of metal, or heavy plastic/wood. i replace it with strong foam. it protects the camera during crash (you'll have to redo the foam, but it absorb the shock). with a bit of patience you get perfect focus, for anyone who's suspicious I use strong styrofoam, not epp and the like for this.

- various step up/down, i try to use everything 5 (or 5.5v) with a single voltage conversion and filter, most equipements have step downs to go from 12v to 5v. its heating up a lot, waste energy. not only you can get rid of the heavy heatsink in some cases, but also get some more battery time (= weigth)

- antennas: i make my owns, mesure them, trim them and solder them. a LOT lighter.

- wire length: i don't care all that much about that. it's not that heavy, and its more convenient to have more than not enough (that means 5cm too much, not 2 meters..). the important thing is to use a good, isolated, thin wire. my wiring is a lot thinner and lighter than regular servo wires. heck its even easier to put around ferrites shall you need that

- single battery setup - no need to say more about the weigth savings there

- battery power: depends on your style of flying, but i like it light. so if your plane doesnt need a 3S to fly, why not use a 2S? similarly for 2S=>1S. My 85gr plane is of course 1S. it cannot go up vertical, but that's not what I care about.

- components choice: i like to have the bare minimum, so no extra sensors. i'm fine with gps speed and altitude reports e.g. (no "baro", "speedo", "multi-board-osd" etc) don't have a current sensor either.

- pan & tilt: don't have this. its damn heavy and complicated. maybe one day i'll change my mind, but i dont like the dual-heavy-servo-and-lost-of-plywood mechanism. it feels like stuff just waiting to fail/break.

i think that's it for my list

Example of the above fpv setup (its so small i dont use an OSD on this):



it could be made a bit lighter: didn't remove all the heatsink (its rly not heating up at all), the shrink tube could be electric tape (actually i'm going to change that this evening ;p)
the camera could be replaced by a flytron FC420 when they're released. im not sure about that one yet tho, my camera is just a few gr. more and better quality.
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Old Jan 28, 2010, 12:19 PM
Engineer for Christ
IBCrazy's Avatar
Amherst, VA
Joined Jun 2006
10,542 Posts
Several of my planes are just heavy by nature. I cut back on the power system. Since I'm not constantly in a bank like when flying point of view, I can cut out some motor weight.

For example, my P-38 weighs in at 36 oz, with all FPV gear on board. It weighs 31 without it. However if it was a point of view airplane, I would have about 2-3 oz more motor in it. So it would weigh 34 or so.

Also, try to keep you power system as close together as possible. Those thick motor and battery wire leads add up to quite a bit.

I also build my own TX antennas which saves about an ounce. Check my blog on how to do that.

Another thing I do is build my own motors. A hand built motor will have between 25% and 200% (depending on the motor) more power per unit weight than a stock off the shelf unit. Most of my motors are rewound Tower Pros and Turnigy's and there are a few Scorpion and GoBrushless kit motors. Again, how to do this is in my blog.

-Alex
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Old Jan 28, 2010, 01:01 PM
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New Bern, North Carolina, United States
Joined Oct 2004
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Here is my Radian build... no tilt, but I do have pan using a S60 servo to keep the weight down. Things I didnt do but will on the next build... solder wires together to reduce weight...thats it... I have all the sensors you could want...GPS, altimeter, airspeed, OSD Pro, Data logger. I have the L-C filter for the vTX and a seperate CC BEC to power the RX and servos. Running a single 3s 2200 lipo I dont have any power induced transmission issues on the video or chatty servos. I would move the pan servo forward an inch if I did it again... I had to add 1oz of lead up by the motor to balance with the lipo all the way forward...but I have a birds nest of wires in the tail where the OSD Pro...I would have used shorter extension wires from the servos to the OSD Pro (for the RTH feature or skipped the RTH feature all together since I dont fly that far away). No idea what my AUW is but she still launches at a few clicks over 1/2 throttle and inthe video you see the nose point up under WOT and drop when I kill the throttle so the weight isnt hurting her. I have since mixed insome down elevator for WOT but the weather sucks so I cant test it.

http://www.rcgroups.com/forums/showthread.php?t=1178047
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Old Jan 28, 2010, 01:51 PM
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Houston Texas
Joined May 2008
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I just replaced my 12V vTX with one that's 5V. It's a lot lighter.
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Old Jan 28, 2010, 01:58 PM
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New Bern, North Carolina, United States
Joined Oct 2004
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true but then you need to step down the voltage...
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Old Jan 28, 2010, 09:29 PM
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trappy's Avatar
Austria
Joined Feb 2007
6,411 Posts
The best way to save weight is to buy a smaller motor and lighter battery. When I build gliders I spec my battery according to the maximum C rating. My new glider pulls around 62Amps, my battery is rated for 66Amps continuous discharge.

You could also share +/- from servos that are located at the same place (pan & tilt), for example. Use lighter cameras and focus on shaving weight off the back as it gives you the greatest benefit. 1g at the tail translates to 5-6g less weight needed to balance on the front.

I wouldn't worry all too much about keeping the weight down, though ... having weight can give you added stability and more speed. It's no use having a flying feather when the wind is up. Likewise, a flying brick won't give you any airtime. Try to find the suggested manufacturer's weight and try to achieve that weight with all your FPV gear on board.
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Old Jan 29, 2010, 01:15 AM
Flying with the eagles
etman's Avatar
Eagle's nest
Joined Nov 2008
2,121 Posts
It is important to choose a plane that has very low wing loading when clean then it can take on more load.

Jimbob00, it's amazing how minimalist you can be.
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