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Old Jul 21, 2003, 09:01 PM
Burnin' holes in the sky!
SkyPyro's Avatar
Gilbert, AZ
Joined May 2003
2,848 Posts
Oops, same time. I would use the 3s 2100 TP pack, which should be good up to 21 amps average, and more peak, so it should be ok.
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Old Jul 21, 2003, 09:12 PM
FoamyFactory.com
Tim H.'s Avatar
USA, TX, Fort Worth
Joined Nov 2001
4,356 Posts
Correct. I have the e-tec parameters in motocalc. Nominal voltage for a 3s pack is right around the same as a 9 cell NiMh pack. So, whenever I calculate for lipos, I use 9 cells in the cell count box. 1.2vx9=10.8v

Tim

PS - I know about the heat! Last thursday it was 109 (heat index of 111) here in Wichita and Phoenix was only 102. It was 101 here today with 20mph winds. I was going to test fly the anti-twisting mods but the wind never died...
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Old Jul 21, 2003, 09:12 PM
FoamyFactory.com
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USA, TX, Fort Worth
Joined Nov 2001
4,356 Posts
Yup...
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Old Jul 21, 2003, 09:51 PM
Burnin' holes in the sky!
SkyPyro's Avatar
Gilbert, AZ
Joined May 2003
2,848 Posts
Maybe it was the time difference, we are on the same time as California, Washington etc, so there is quite a difference. I think it also gets a bit warmer down here, plus the fact that I fly mainly off of grass, which raises the humidity. In about 5 minutes of just standing, I am already sweating!!! I think I will get the LiPo's anyways, just for the weight savings and increased power. I think I would lose about 3 ounces compared to a 9 cell HeCell pack, which is a lot!!! Man I gotta find a nearby gym to fly at!

Dan
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Old Jul 21, 2003, 10:53 PM
FoamyFactory.com
Tim H.'s Avatar
USA, TX, Fort Worth
Joined Nov 2001
4,356 Posts
It was at 5pm local, which was 3pm your time. The only reason I know was because I was talking to some one at our corp. headquarters in Phoenix. All I know is I don't like it when it's that hot here. I spent a year out in 29 Palms CA and many 136 degree days and those didn't seem nearly as bad. This Wichita heat sucks! I miss the beach!

Tim
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Old Jul 21, 2003, 11:21 PM
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ptca's Avatar
Chico, CA
Joined Jun 2003
44 Posts
I'm still using a 720 mAh 8 cell NiMH pack in my 3DX on a retimed GWS 300C -D. The prop is a 12x6 GWS. I used to get 8 to 8 1/2 minutes but now get around 7 1/2 minutes. At the end of a flight, the pack is hot enough to burn me. How hot should the pack get? Is my pack being damaged? I've got about 15 flights on the pack and motor.

Chris
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Old Jul 21, 2003, 11:28 PM
Burnin' holes in the sky!
SkyPyro's Avatar
Gilbert, AZ
Joined May 2003
2,848 Posts
There are standard NiMh's for ya. Mine did the same thing, i had to do the battery toss to keep from burning my hands. You are definately drawing too much from the pack, go down in prop size! I think an 11x4.7 should be good. Your battery pack will never be the same, however.

Dan
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Old Jul 21, 2003, 11:29 PM
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south central kansas
Joined Jul 2003
571 Posts
TRY USING A 9 X 4.7 PROP. i AM USING THAT WITH THE SAME RETIMED MOTOR AND LIPOS. I AM GETTING 15 TO 18 MIN FLIGHTS WITH THE NOSE POINTED STRAIGHT UP MOST OF THE TIME.

MIKE
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Old Jul 22, 2003, 02:31 AM
Holger Rusch
Prof. Dr. YoMan's Avatar
Germany, Karlsruhe
Joined Apr 2003
415 Posts
I dont understand why you want these BIG motors with the lot of power they draw?

Hacker is about 100g with gear i guess.

There are motors out, which could produce at least 350g static thrust with two lipoly cells and dont get on the limit of 1200 e-tec's. And they got a weight of only 45g.

This is 55g saved for the motor and 25g saved for the cell. All together 80g saved.

It is easy to get the 3DX or UltiBipe below 250g with this setup even with landing gear. You could even stop hardening some stuff with carbon and only use strapping tape. And its much better to fly then. And SLOWER.

My Bipe (pictures at the end of the old thread) is 300g now after some crashes and fixes and I will go for a new motor and put one cell out to get at least 50g weight saveings and more fun.

PS: 1g ~= 0,035 ounces

GO FOR SMALL AND LIGHT AND NOT BIG AND BLOATED.

Check here for a friend of mine and what he can do with these light ones. Around 250g. http://sites.inka.de/engist/manuel/vid/einfachgeil2.avi
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Old Jul 22, 2003, 05:49 AM
Registered User
Singapore Holland Rd
Joined Mar 2002
1,920 Posts
Hmm so Does the strapping tape along the fuse really help bcause I already reinforced mine with 4 1mm thick balsa strips
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Old Jul 22, 2003, 07:56 AM
rehsarCeoJ
JoeCrasher's Avatar
Glenmoore, PA
Joined Jul 2003
253 Posts
jperch

Thanks for the heads up on the prop - I stopped off at the local hobby store & picked up some props on my way home last night.

With the 11 x 4.7 prop my little 300C was great - no more need for full throttle all the time.

It's amazing what a prop change will do for you...

TIP - don't change out your prop on grass. I dropped the nut that holds the prop on & it took about 20 minutes & two neighbors to find it!


Joe
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Old Jul 22, 2003, 08:02 AM
Registered User
Singapore Holland Rd
Joined Mar 2002
1,920 Posts
My friend has a real strong magnet so if it falls just take the magnet n done!
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Old Jul 22, 2003, 08:54 AM
Burnin' holes in the sky!
SkyPyro's Avatar
Gilbert, AZ
Joined May 2003
2,848 Posts
Quote:
Originally posted by Prof. Dr. YoMan
I dont understand why you want these BIG motors with the lot of power they draw?

Hacker is about 100g with gear i guess.

There are motors out, which could produce at least 350g static thrust with two lipoly cells and dont get on the limit of 1200 e-tec's. And they got a weight of only 45g.

This is 55g saved for the motor and 25g saved for the cell. All together 80g saved.

It is easy to get the 3DX or UltiBipe below 250g with this setup even with landing gear. You could even stop hardening some stuff with carbon and only use strapping tape. And its much better to fly then. And SLOWER.

My Bipe (pictures at the end of the old thread) is 300g now after some crashes and fixes and I will go for a new motor and put one cell out to get at least 50g weight saveings and more fun.

PS: 1g ~= 0,035 ounces

GO FOR SMALL AND LIGHT AND NOT BIG AND BLOATED.

Check here for a friend of mine and what he can do with these light ones. Around 250g. http://sites.inka.de/engist/manuel/vid/einfachgeil2.avi
My plane is so heavy and uses a Hacker because I don't fly much LiPos. I need the extra thrust to pull my NiCds and NiMhs around on less voltage and more weight. Also, the other motors are out there, but I have no idea how to get a doppelwopper and how much it would be (just the shipping would be a nightmare!) Another problem is that we don't have cheap access to the depron you guys use, which adds an ounce right there. BTW I would like to see how you strengthened your plane with strapping tape, it just doesn't seem like it would be enough. Thanks,

Dan
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Old Jul 22, 2003, 08:57 AM
Burnin' holes in the sky!
SkyPyro's Avatar
Gilbert, AZ
Joined May 2003
2,848 Posts
Oh, and a B20L weighs 68.5 grams, the B20S weighs 51.5 grams.

Dan
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Old Jul 22, 2003, 09:40 AM
Holger Rusch
Prof. Dr. YoMan's Avatar
Germany, Karlsruhe
Joined Apr 2003
415 Posts
Motors e.g. here: http://www.aircraft-world.com/prod_datasheets/pjs.htm

Stiffening of fuselage with cross-strapping-tape ( http://www.epp-fun.de/Sonstiges/strapp3.jpg left one) over the top and the bottom. I added a 3mm carbon rod.

Stiffening of the wings with normal-strapping tape (right one) on every side of the wing. Thats enough for the ulti.
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