|Jan 21, 2004, 12:14 PM|
3D Fan Fold 3DX, Ultimate Bipe and Yak54...V9
It's time for part 9!
Here are the previous links:
|Jan 21, 2004, 12:37 PM|
2 Servos And Bug Fix Question
Hi, I'm very interested in the dual elevator servo setup as i'm planning on blowing one of these up to somewhere between 45-50" span and with the increased wing area I don't think the added servo weight would be a hindrance. It would also take some of the load off the servos back there and would help the elevators to stay at the commanded positions. I think it would also help with elevator twisting which is something i've have just now noticed is a problem on my first yak. It causes the airplane to roll out in the top of large loops, and at first i thought it was a trim issue that i needed to work out but later fowun out it wasn't a consistent thing and started suspecting twisting. I did prove this by getting a neighbor to watch the plane through binoculars and explained to him what i was wating to watch for. He did confirm my suspcion. I am always looking fdor ways to better these. They fly very well...actually surprisingly well for what they are, but there are some little bugs I'd like to work out of them to make them fly real nice and precise on different manuevers. I did check my elevators to be sure they were exactly level and they were not twisting while moving on the ground. They track perfectly. They only twist from the prop slipstream, and when they have a load on them...they higher the load, the more they do it. Any discussion on the 2 servo idea (pros and cons) and this twisting issue would be very helpful and much appreciated.
|Jan 21, 2004, 12:50 PM|
One thing is that you will need higher torque servos as mine are at their limit right now. In fact my criss-crossing linkage is slightly binding just enough that the servos have a hard time self centering while on the ground, but in-flight it isn't as bad since the airflow seems to help them out. That is why I may go to 4 servos linked with simple "Y" harnesses instead of the long linkage. This will eliminate any flexing in the linkage and also give better authority to each control surface without much of a weight increase. My Naro + servos weigh 13 grams each and can be replaced by 2 pico std servos at 6 grams each and add the extra wire weight and you are pretty much even. I do have a separate rudder servo too. I'll try to get you guys some pictures tonight.
BTW, Tim, congrats on such a popular thread !!! Maybe we should be contacting Guiness Book of World records !
|Jan 21, 2004, 01:08 PM|
This thread is like the Energizer Bunny..
It keeps on going and going...
Great work Tim..
Glad you got moved Birdie...
|Jan 21, 2004, 01:18 PM|
EPS-350C Variations & Field Experiences
I ran the numbers in MotoCalc for the Foam Factory recommended GWS 350C + 2s + 12x6 . It seems to unload very quick, to the point that a 12oz model might not fly well (climb rate is estimated at only 321ft/min). A 12x7 (which isn't available), or a GWS 12x8 (1183ft/min) seems to actually fly versus just hang/hover.
I started the following thread, actually hoping to get more involvement from the 3D Flying crowd, but I gather you all don't visit the Power System forum all that often. Would very much appreciate the 3D'ers that use the 350C come visit & contribute.
|Jan 21, 2004, 01:30 PM|
OK i was waiting for V9 before i posted this.
Here is my new plane based on the 3DX.
I made many changes, first I made the fuse longer and increased the fuse height, and changed the shape. I reduced the sweep in the wing and added another inch or more of chord. I enlarged and changed the shape of the tail surfaces. Basically the only thing the 3DX and this have in common is a 36in wing and the wind and horozontal stab is on the thrustline. I might shockify it and I think it would make it even stronger with minimal weight.
Here are the specs.
405 in of wing area
Motor Himaxx 2025-4200
GWS C drive (5.33/1)
12 x 6 prop
Motocalc predicts 34oz of thrust
Bare airframe weight in pic with CF I-beam is 5.5oz or 156grams
CF I-beam is .007 x .5 for the sides and .007 x .25 for the center part. Very strong and not much weight. (I like the I-beams and my LHS always has them in stock )
Here is a pic, hope you like it.
Last edited by Mattfly; Jan 21, 2004 at 01:34 PM.
|Jan 21, 2004, 02:21 PM|
Ok, about time i chime in here!
I have loved the look of the 3DX ever since i first saw the prototype that Tim H built a while ago. Every time i had an extra sheet i was going to build one, but i never did, lol.
I got around to building a Micro 3DX, but i never realy flew it, but a few days ago, i traded the micro 3DX and my Matrix 3D plans for a prebuilt 3DX!
I got a chance to fly with with a lipo/mega BL set-up and it was awsome. But my mega BL/battery set-up is a bit big for it.
My plan is:
8 cell 730 AAA NIMH.
EPS 350 D with a 10x4.7
This gives me 17 OZ of thrust for just 9 amps, seems like it will be easy ont he batts and still give me good power.
My BL set-up is a Mega 16/15/8 and an 8 cell 1050 KAN, it's a bit heavy for the wing area of the 3DX, but it worked supurb on my larger Matrix 3D.
Any input on this set-up?
|Jan 21, 2004, 02:28 PM|
Joined Aug 2003
You may want to try Kan650s instead of the 720AAA - much better current output, same duration. The 720AAA cells have gotten alot of bad press around here. And why only a 10x4.7? I doubt you will get very good hovering ability w/ the 720s and a 10x4.7. Go with the 12x6. And for a bit more money (if you already have a charger) a 2s Kokam 1500 or Etec 1200 will work great.
|Jan 21, 2004, 02:32 PM|
I don't have the money for the batts and charger right now, but hopefully in a few months i will.
GWS says don't go past a 11x7 for the EPS 350 D gear. But it looks like on the GWS prop chart, the 10x4.7 will give me the most power on 8 cells. A 12x6 will draw more than 10 amps, and the AAA cells preform fine at under 10 amps, over that they sag BIG time. If i stay under 10 amps, the cells will probly prefrom fine.
|Thread||Thread Starter||Forum||Replies||Last Post|
|3D Fan Fold 3DX, Ultimate Bipe and Yak54...V8||Martin Hunter||3D Flying||526||Jan 21, 2004 12:15 PM|
|3D Fan Fold 3DX, Ultimate Bipe and Yak54...V7||Martin Hunter||3D Flying||522||Dec 31, 2003 06:01 PM|
|3D Fan Fold 3DX, Ultimate Bipe and Yak54...V6||Martin Hunter||3D Flying||541||Dec 14, 2003 01:22 AM|
|3D Fan Fold 3DX, Ultimate Bipe and Yak54...V5||Martin Hunter||3D Flying||520||Nov 25, 2003 05:32 PM|
|3D Fan Fold 3DX, Ultimate Bipe and Yak54...V4||Tim H.||3D Flying||718||Nov 10, 2003 12:11 PM|