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Post your giant scale electric conversions!

Old 01-15-2016, 08:13 PM
  #26  
kyleservicetech
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Originally Posted by Ron View Post
ahh yes...we were flying large models quite a few years back, but it seems that back then they didn't need 100 watts to the pound to fly :-)

seems to me that if you had 60, you had a very spritely model....now unless you have 100 or so, everyone says it won't fly :-)
did the watts get smaller while I wasn't looking?
Back in the late 1990's, I built up a giant scale Piper Cub with a 120 inch wingspan. Power was an Astroflight Geared 90 brush type motor, with 38 sub C nicad cells and a 20X10 prop. Power was around 1000 Watts, or 70 Watts per pound.

It flew like the full scale Piper Cub, but doing a loop required a dive first to gain flying speed. And a simple roll was nearly impossible.

If that model hadn't been sold, it would have been interesting to hang my Hacker A60-16M motor on it. But, that 2500 Watt power system might have ripped the front off of the Cub.
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Old 01-15-2016, 11:45 PM
  #27  
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sounds like the cub flew just like a cub :-) The full sized one had just enough power to kill you :-) Loops are done with a dive first...so are rolls, and even wing overs. " extra" power was not an option......
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Old 01-16-2016, 04:22 PM
  #28  
Larry3215
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Originally Posted by fhhuber View Post
Official IMAA/IMAC rules state: minimum 80" wingspan, 60" wingspan for biplanes, 140" combined width and length for jets, or true 1/4 scale.
IMAA originated the term "Giant Scale" (back when engines bigger than .61 ci were rarely seen on model aircraft)

There are many aircraft that meet the 1/4 scale without meeting the measurements.
Well, if we can go by the combined width and length definition, then two of my foamys fit the bill - the XXL Polaris and Mega Capricorn! I have (had) one KMP Yak and two other scratch foamy Yakish models that fits the actual wing span requirements
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Old 01-16-2016, 06:45 PM
  #29  
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Originally Posted by Larry3215 View Post
Well, if we can go by the combined width and length definition, then two of my foamys fit the bill - the XXL Polaris and Mega Capricorn! I have (had) one KMP Yak and two other scratch foamy Yakish models that fits the actual wing span requirements
Wow, Foamies have come a long ways from when they were just something used to get into the air!

(Prime example is the CarbonZ Cub)
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Old 01-17-2016, 03:04 AM
  #30  
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Originally Posted by kyleservicetech View Post
Wow, Foamies have come a long ways from when they were just something used to get into the air!

(Prime example is the CarbonZ Cub)
yeah, and while not giant scale the new Prometheus from horizon is going to be pretty sweet too.

http://www.horizonhobby.com/carbon-z...asic--efl10950
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Old 01-17-2016, 06:14 AM
  #31  
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Originally Posted by firemanbill View Post
yeah, and while not giant scale the new Prometheus from horizon is going to be pretty sweet too.

http://www.horizonhobby.com/carbon-z...asic--efl10950
That is sweet!
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Old 01-20-2016, 08:52 AM
  #32  
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wow, gigantic planes.
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Old 01-28-2016, 01:21 PM
  #33  
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How bout some Golden Oldies, the Mud Ducks. These were originally designed for fuel set ups. Mine are the Agri Duck versions. 9 1/2 feet of w/s.
Both of mine converted to electric. AMA's Dave Matthews was present when the yellow one flew it's maiden in New York. Had the green one set up with a charcoal dust hopper in it. On start up it would spew a cloud of "smoke" from the "engine" Had the fuel guys scratching their heads. It's like piloting a blimp when you fly these. They don't go anywhere fast, and take forever to turn.
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Old 03-04-2016, 01:34 AM
  #34  
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FINALLY ready to go
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Old 03-04-2016, 03:16 AM
  #35  
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That looks amazing, what great detail!
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Old 03-04-2016, 03:53 AM
  #36  
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Once my CG Lancaster is up and RTG ... I will post piccies here ...

She was designed for 4 x 25 Glow engines ... and I will fit 35 size 1450kv motors instead ... should be good for a laugh anyway ..

Nigel
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Old 03-04-2016, 06:54 AM
  #37  
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porcia:

Thanks for the kind comment ..the pictures don't show the rib stitching or the smaller details, but you get the idea :-)

Last edited by Ron; 03-04-2016 at 09:15 PM.
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Old 03-09-2016, 05:18 AM
  #38  
kyleservicetech
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Default Peak Models giant Edge model

This is a 95 inch wingspan model with 1450 square inches of wing.

The weight is exactly 20 pounds. Power system is a 12S3P A123 2500 Mah battery pack with a Rimfire 50 cc electric motor, 22X10 wood prop, and a Castle Creations 120 Amp Talon ESC. The power system turns the prop at 6800 RPM on the ground, pulling 125 Amps at full power. (The Talon ESC gets a direct blast of external air through the bottom hole in the cowling.)

At 4500 Watts on a 20 pound model, it should get off the ground OK.

The model is equipped with a two cell 2500 mah A123 battery for receiver backup power.

It has not been flown yet, still waiting for when it is safe to roll the clubs flying field with the clubs tractor and two ton rollers.

A photo is attached.
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Old 03-09-2016, 06:11 AM
  #39  
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Hi Denny ....

Power system is a 12S3P A123 2500 Mah battery pack with a Rimfire 50 cc electric motor, 22X10 wood prop, and a Castle Creations 120 Amp Talon ESC. The power system turns the prop at 6800 RPM on the ground, pulling 125 Amps at full power.
I'm just looking at your quoted battery pack ... 2500mAh ? Motor draws 125A ? So at full throttle you get 1m 12s till flat battery ? Is there a 0 missing somewhere in the mAh ? And I know you will not be WOT all the time ... but it still seems a bit small on battery capacity ...

or is the 3P actually meaning 3 x 2500 = 7500 total capacity ?

Beautiful model anyway ...

Nigel
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Old 03-09-2016, 06:29 AM
  #40  
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Originally Posted by solentlife View Post
Hi Denny ....



I'm just looking at your quoted battery pack ... 2500mAh ? Motor draws 125A ? So at full throttle you get 1m 12s till flat battery ? Is there a 0 missing somewhere in the mAh ? And I know you will not be WOT all the time ... but it still seems a bit small on battery capacity ...

or is the 3P actually meaning 3 x 2500 = 7500 total capacity ?

Beautiful model anyway ...

Nigel
Yup, that's 12S3P for 39 A123's at 7500 Mah.

Really thought about LiPo's, but A123's CAN NOT ignite like a LiPo can. And, those A123's test within a few percent of each other at high current levels.

The A123's are about 1.5 pounds more weight than a similar LiPo setup.
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Old 03-09-2016, 06:51 PM
  #41  
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Well to be totally fair, when was the last time you've seen a LiPo fire? I've only seen one from a catastrophic crash.. I'd rather have the better power/weight ratios, but that's just me
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Old 03-09-2016, 07:48 PM
  #42  
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Originally Posted by Xpress.. View Post
Well to be totally fair, when was the last time you've seen a LiPo fire? I've only seen one from a catastrophic crash.. I'd rather have the better power/weight ratios, but that's just me
Members of my club have had three LiPo fires in the past couple of years, usually smaller packs. The chargers were NOT Hitec units.

My concern with LiPos, especially when getting into the 12S 8000 mah class of battery pack, is who makes the most reliable, highest quality battery this month?

After reading the hundreds of postings on this subject, there really isn't a clear answer.

Compare that to those overweight, oversized, undervoltaged A123 packs that typically measure within a few percent of each other in voltage under load, and milliampere hour capacity. Even on A123 cells that were manufactured several years apart.

Add to that, the Mah capacity and voltage under high current loads doesn't change a lot after 5 years and 500 flights. Case in point, one of my 5 year old, 500 flight 12S2P packs turned the 19X12 prop for a Hacker A60-16M motor at 6500 RPM. But, it's milliampere hour capacity dropped to around 75% of original. A brand new 12S2P A123 pack turned the same motor and same prop at 6700 RPM.

My models have over 140 A123's for motor power, and the above is typical of their lifespan. I'm charging them at 10 Amps per cell with a pair of Cellpro PL8 chargers.
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