well...i am ready to go to canada...wish i could figure a way to get my 3dx into a suitcase! but at -10, it would probably freeze up in the air and shatter on impact!

Originally posted by birdie_in_texas
well...i am ready to go to canada...wish i could figure a way to get my 3dx into a suitcase! but at -10, it would probably freeze up in the air and shatter on impact!

Birdie, Isn't that a normal flight for you?

Just kidding!

Joe

I found out yesterday that FFF doesn't like temperatures below 40deg. F ! I maidened a profile GeeBee I made and one of the aileron links didn't glue good due to the temps. so I put it in kinda hard and the wing just shattered in a straight line and snapped off. Darn cold!

I think this happened to me too... I think. The week before last, I stalled it at about 10-15' altitude. I throttled and pulled... and almost got out of it. Ended up nosing in at about a 30 degree angle. It was about 43 degree F as I recall. The nose fold over and broke just behind the motor mount hardwood stick. Didn't seem like I hit that hard!?!?
I glued it quick with CA and zapped it with some excellerator, changed the broken prop out, back in the air within a few minutes.

It didn't really cross my mind at the time, but now that you guys mention this cold stuff, you've got me wondering.

BTW, this model was built from the pink Dowel Corning stuff.

Originally posted by jperch
Birdie, Isn't that a normal flight for you?

Just kidding!

Joe

Ha..!! unfortunately, it happens all too frequently!! but at least i could blame the cold!! hahaha

I figured out what was wrong.
My new batt pack
I friend at work brought his Triton in. set it all up. and we were only getting 300ish mah's out of a 750 pack and about as soon as the Triton got the load on, the 8 cell pack it droped to about 7.8 volts. almost right away.
So that's it. I'm not very happy with this.
I really think that this 3DX will be a good airplane once I get some batt's that will perform. Need to try a 3 cell poly before giving up on these parkflyers for good.
Rick

Rick

You could also try an 8-cell pack that actually works.

The only reason why I haven't joined the li-poly revolution is that I'm too cheap to spend the $150 for a decent charger and a few packs.

tolladay,

Man, you're right about the $150 for a decent charger. I bought an Apache... and it does a pretty good job of charging, but after using Dymond Super Turbo for my nicads, it's just not the same. You really need the readouts on what's happening. Looking at a red or green led and watching the clock just isn't doing it for me.

Originally posted by RiBell
Need to try a 3 cell poly before giving up on these parkflyers for good.
Rick

Rick..that is almost the direct sentiment I expressed, except I already had the lipos. I had been flying lipos from the get go, but I had 2 packs of 8 cell 720 NiMh. SO I slapped one on..it had been cycled a couple of times..and it gave such lackluster performance I said right then that if that's all these things would do I would have been out right then and there.

At that time I was just testing the water..I had one 3S lipo pack and the $35 BEL charger, didn't want to get in too deep until I got to see for myself. Now I have a couple more packs and a decent charger.

FWIW, I have the Apache 1500 and like it fine..I don't really need anything but a red or green light...all I have ever done was checked the voltage with a VOM after successively longer flights to see where the voltage dropped to.

Triton got the load on, the 8 cell pack it droped to about 7.8 volts

That's a problem with some of the NiMh cells, especially the small ones - they have poor "voltage depression" characteristics. You can't use just any old NiMh in our application. You need some of the ones that have been proven to hold their voltage under load. It's no big deal in a flashlight, but when we put a load on them and the voltage drops severely, our RPM drops proportionately...

I posted about it earlier in one of these threads. I almost gave up on e-flight when I first tried it because I had a whole bunch of "turd" NiMh batteries

RCL,
I have been doing the Li-poly build/destroy/autopsy thing for about 1 1/2 years now. I am a physicist here at Sony but I am not in the battery section but have access to some of their battery people when I need it. Enough of the background.

You can "re-start" a low voltage cell using the method you just mentioned. I have done it for 25 or more cells than came in from Sony where they had sat so long in storage that they were at .01 volts per cell! You use a constant current charger at 1/10 C for about 10 minutes. You are absolutely right to stand right there in front of the cells and "feel" them every few minutes. Absolutely do not take your eyes off the pack. They can swell up and explode in 10 minutes time! See this thread for the explosion:
http://www.rcgroups.com/forums/showt...hreadid=160079

If after 10 minutes of this low charge, the cell voltage has not reached 3.0 volts, then the cell is bad and MUST BE DESTORYED! Why? because even if you manage to get it to take a full charge with more charging at constant current, there has been internal damage to the cell chemistry. What happens typically is that the cell will quickly swell-up upon a later recharge after use. I have been "blessed" with about 10 of these "living dead" cells. If you happen not to be in your garage when they swell, then they will swell up very large, vent, and sometimes catch fire! Unless you are really in the market for a new house, you don't ever want to risk this possible outcome.

Why do I paint such a firey picture? I do not want anyone to be injured or loose a house because of Li-poly technology. I am a total believer in Li-poly for r/c aircraft. It just needs to be treated with a great deal of respect. Please see this page about how Li-poly should be used: http://www.rcgroups.com/forums/showt...hreadid=149283

It can be a real life-saver. Remember, a Li-poly that is swollen or is getting hot (like 104 deg F) during recharge means that you have a time-bomb on your hands. Remove it IMMEDIATELY from the charger, put it on a cement floor far away from flammable materials, and let it cool. Then dispose of it as mentioned in the threads I have cited. I have something like 300 flights on my 3DX look-alikes and none of them would hover if it were not for Li-poly technology. But everytime I land, I feel the pack for heat and swelling. I never leave a Li-poly on a charger for more than 10 minutes before I "touch" it again. I have twice come close to having the "flaming garage" syndrome. I never want to be in that position again.
Ted Cooper

tjcooper,

Thanks for the reminder!


All,
Will a 2S TP2100 be okay with a GWS350C (DS 6.6:1) motor? The reason I ask is that the LHS has been out of stock on the 3S for a while, but has the 2s. Would something else be a better choice? The easy answer is to wait, but you know that is easier said then done!

-MO

Mo,

Here is a link to a post I made in V4.

http://www.rcgroups.com/forums/showt...89#post1471089

It decribes the exact setup a buddy of mine is using on a UB. He uses a 2s lithium pack for power and it flies very well. The only problem you might have is that my friend is not using the TP2100's. The extra weight might make a difference but I can't say for sure.

I hope that helps,
Joe

my dog decided to chew one of my etec 1200's up...it "blazed" my couch and burned into a feather pillow...maybe the only thing that kept everything from catching fire...walked into a house full of smoke and a lovely electrical burning smell..i almost Profanity removed by moderator myself....i consider myself extremely lucky that the house did not burn to the ground and that the dog appears to be ok...

i now take extra precautions in where i store my li-po's while in the house...

anyways..just though i would share..

birdie

Ted,

Man, am I ever glad to have your information!!

I had been cautious simply because of the warnings on the sheet that came with one of my packs. It seemed they were cautioning of something catastophic, but didn't really say it. The pictures at Jimmy's R/C Hanger site are alarming. These pics should be placed where everyone must see them prior to using these packs!!!

The remainder of your information will undoubtedly be very useful into the future and I intend to copy and archive.

Question: Would you mind if I quote any parts of your words? I can re-word if necessary, but it seems you've made it crystal clear.
I don't want any credit here, but I have a small website, and I really believe this info needs to be spread far and wide for the hobbiest's protection. I had no idea this explosion and fire would be so violent.

Wow, I'm still shaking my head. Unbelievable!!

I have to wonder about that glass bowl, shown a few posts down, in the later link. Is that Pyrex maybe? Although Pyrex is good in an oven and it's hard to break, I've seen a piece or two of it break. It turns to slivers and almost explodes by itself. I would have to wonder if that's a good container to use.

Thanks again!
I'm off to find a suitable container <grin>.

Mark