Battery Selection - Edge 540

[tdarst]

I am using TP1320's with an APC 10x 4.7SF. I would like to get a bit more flight time than I do now (10 minutes, average) without sacrificing much in the way of power/vertical performance. While browsing the TP website, I noticed they have a TP2000-3SPL, which is rated for 25 amps continuous, 40 amp burst; the 1320 is 17 amps continuous, 27 burst. The specs list the 2000 at 120 grams, where as the 1320 is at 84 grams (1.3 ozs more). With a fully charged 1320 / 10x4.7SF, I am pulling ~20 amps, producing 200W at ~7500 rpms, static (Hacker A20-20L). While the 2000 is 1.3 oz. heavier, with the higher amp rating, I am thinking I can "prop-up" a bit to offset the extra weight. Plus, the extra weight might make the plane able to handle the winds a little better (already handles them pretty well, that was not a criticism). Anyone have any thoughts on this? I am particularly interested in them if you have already tried it! - Tony

[tdarst]

...I guess I will be the first to try it (although that's hard to believe). I'll issue a followup when I get my hands on one.

TD

[king160woody]

I use the Vislero 2100's at 20 C from the 3dxhobbies.com site. They work great and have super long flight times. I'm using a motor that takes more amps that the hacker, "Scorpion 2215-18" on a 10X5E prop. It smokes the hacker hands down! Anyways, I was using this motor as a comparision. I get about 10-12 minutes with this motor PUSHING it, soooo you should get around 15 minutes with a 2100 and the extra weight doesn't really affect its performance that much. I sometimes prefer the extra weight for like you said wind, precision flight, and some tumble manouvers.

Woody

[tdarst]

Wow... Vislero, eh? They are less expensive, can deliver more current and have more capacity. I was worried about getting into a battery that weighed that much... 150 grams seems pretty heavy; almost double what I am using now. But if you say it's okay, it must be okay!

TD

[king160woody]

Yup, I have had a lot of luck with the Vislero packs. When using a bigger batt. make sure to lateral balancer your plane. It will make a big improvement in its flying.

Woody

[tdarst]

This is the lead in:
A few days ago, in a galaxy a couple of rooms away...

I put a penny on the wingtip opposite side of the battery; it balanced it perfectly. Then I added the large Edge 540 decals to the battery side wingtip. Checked the balance again, I had to add a dime to the penny side (it surprised me it took that much, but it did) to re-balance it. Mind you, this is with the wings level.

I have had a problem from day one (about 13 days ago) with it tucking towards the LG in knife edge (pretty hard, not subtle).

I spoke to Paul about it, he suggested the original lateral balancing (i.e. penny), AND shifting the CG aft to 4". I did both, and it still wants to tuck towards LG in knife edge - albeit not as bad, but still pretty pronounced.

Now, the final set up: With the plane RTF (battery mounted) - when I check the "lateral balance" while holding the plane in the knife edge position (i.e. wings vertical) - it tucks really hard to the gear... which makes sense because the battery is below the wing and therfore the centerline of the fuse AND the center of mass of the whole thing (the battery is a pretty heavy item in relative terms!).

Finally, the question: Is this is what is causing the LG tuck during knife edge, or do I have a wing incidence issue? If the former, what do I do about it; any ideas? FYI.. the control surfaces are about as neutral as the naked eye can see them; the plane flies straight and level (upright) at ALL throttle settings except really reduced to no throttle, in which case it pitches up slightly and slowly as speed bleeds off (not at instant the throttle is cut). To me this is just indicative of having a slighty aft CG, as intended.

Man, I sure need some help with this one... I have all kinds of crazy (testing) ideas running around in my head to get to the bottom of it... I would much prefer to learn and solve it based on other's experiences.

TD

[tdarst]

Woody... haven't heard from you regarding my last post - but that hasn't stopped me from dinking around some more. In my last post, I essentially rationlized that the CG of the plane needs to be correct on all 3 axis... X, Y and Z. Just to be clear, X is fore/aft along the fuse; Y is left to right along the wing (previously you refferred to it as "lateral"), Z is top to bottom through the canopy region to the bottom of the fuse.

In Realflight with the AirFoilZ Edge 540 model, I adjusted the value of Z from it's default of -0.2 (if I recall correctly), to -2.0, thus lowering the intersection of all 3 axis in the fuse. Now, that model behaves almost EXACTLY like my plane does (the "gain" is perhaps a little different, but the tendencies are identical)... it wants to roll out of a knife edge (aileron required to hold it) and when rudder is applied, it tuck towards the gear AND tries to roll out a little harder.

Last night, I stuck the battery onto my plane in the vertical orientation... with the leading edge of the battery flush with the rear of the main wing spar line. Checking the fore/aft CG, luckily is it dead on a 4" behind the leading edge of the wing. Now, the interesting part...

Since I have another Edge kit here now (it arrived yesterday!), I am seriously considering turning this one into a bit of a lab project. First, I am going to fly it without the gear (haven't done this yet) as weight being so low and with a large cantilever moment exacerbates the issue. If that helps, I am likely going to cut out a rectangular piece from the bottom of the wing against the fuse, adjacent and to the rear edge of the wing spar, just the size of the end of the battery... and shove the battery up inside the wing until it hits the top skin. This should move the Z-axis CG closer to the centerline... and reduce or eliminate the nasty little trait I trying to rid the plane of...

Stay tuned... this is going to be fun! :cool:

TD

[king160woody]

Let me know how it goes!! You may want to raise your ailerons each abour 1-2 degrees, like a half a turn on the clevis, or maybe even as much as a whole turn. This is so easy to do that I mess with me ailrons all the time. Raising them helps in harriors and helped my kinfe edge problem I had with my first edge greatly. If it gets worse doing this, it will take a whole minute to change the clevis back to where it was =) Be sure to let me know how the battery in the wing thing works out! AND PICTURES...

Woody

[Mikey]

Woody... haven't heard from you regarding my last post - but that hasn't stopped me from dinking around some more. In my last post, I essentially rationlized that the CG of the plane needs to be correct on all 3 axis... X, Y and Z. Just to be clear, X is fore/aft along the fuse; Y is left to right along the wing (previously you refferred to it as "lateral"), Z is top to bottom through the canopy region to the bottom of the fuse.

In Realflight with the AirFoilZ Edge 540 model, I adjusted the value of Z from it's default of -0.2 (if I recall correctly), to -2.0, thus lowering the intersection of all 3 axis in the fuse. Now, that model behaves almost EXACTLY like my plane does (the "gain" is perhaps a little different, but the tendencies are identical)... it wants to roll out of a knife edge (aileron required to hold it) and when rudder is applied, it tuck towards the gear AND tries to roll out a little harder.

Last night, I stuck the battery onto my plane in the vertical orientation... with the leading edge of the battery flush with the rear of the main wing spar line. Checking the fore/aft CG, luckily is it dead on a 4" behind the leading edge of the wing. Now, the interesting part...

Since I have another Edge kit here now (it arrived yesterday!), I am seriously considering turning this one into a bit of a lab project. First, I am going to fly it without the gear (haven't done this yet) as weight being so low and with a large cantilever moment exacerbates the issue. If that helps, I am likely going to cut out a rectangular piece from the bottom of the wing against the fuse, adjacent and to the rear edge of the wing spar, just the size of the end of the battery... and shove the battery up inside the wing until it hits the top skin. This should move the Z-axis CG closer to the centerline... and reduce or eliminate the nasty little trait I trying to rid the plane of...

Stay tuned... this is going to be fun! :cool:

TD


You are right on all points made. First I would go with 4.25 on the cg that is an in between setting for patteren and 3D the second is get the Reciever against the wing. The third is move the ESC is high as it will go above the wing if possiable. The third is get the batt up against the wing. The vertical ballance will always be below the thrust line so at certain angles of attack you will have minimal coupling in knife edge. We are doing testing on the full fuss versions of the plane because we can better deal with this issue getting all the epuipment on the thrust line and have a plane set for 0-0-0 and not just close. If you do those things you will be very happy with the knife edge abilities of the plane. Let me know what you think.

[tdarst]

Well, I decided to bypass cutting the hole in the wing and do some more testing. Between dinking around with home chores today, I played around with battery and ESC placement and flew it. I have a photo, but have no where to host it; any suggestions are welcome. This setup has the fore/aft CG at just over 4" behind the leading edge, I had to remove the penny from the wing for lateral... and in the Z axis plane, it is very VERY close to the thrust line. It ain't very pretty, but boy does it fly GOOD! Besides, with the altitude margin of saftey I keep, I can't see the battery very well, anyway! Good gosh, this thing flies really REALLY well, now. In the photo, you can see where my old battery seat belt is under the wing; I am about to relocate it to the battery's new home. WOW... can't wait to go fly it again! SWEET! - TD :D

[tdarst]

I found the member gallery and posted a photo; will likely replace it and add a few more later. It's a perfect morning for flying here, and almost light enough; pre-flight checks about to begin! - TD

http://www.airfoilz.com/gallery/showphoto.php/photo/52/ppuser/467