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Old Aug 23, 2007, 10:52 PM
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Christchurch, New Zealand
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So, mine will probably maiden this weekend. Can't wait.

I've gone with a Hyperion 3025-08, 13x8 APC E, and 3S 2500 pack. Motocalc says that'll give me about 10-12 minutes of scale-like flying assuming good throttle management, which should be plenty... especially as I own 5 of those packs. I also bought one of the Robart nose struts (after wincing over the LHS price... owww, that hurt! NZ$106!).
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Old Aug 23, 2007, 11:30 PM
Fly allot, Crash allot, next?
United States, CA, Corona
Joined Feb 2006
7,235 Posts
Andrew,

If I read one of the first posts correctly, the AUW is over 8 lbs. If it is, I don't think 3S lipos is going to provide enough power. Am I reading it correctly, 3S, 2500mah, 13 inch prop., and the plane is the same as Tracon's.

The Hangar 9 warbirds weigh almost the same, and it takes 6S, and a 15 inch prop to get it to fly just OK. To fly good it needs a larger prop.

I guess if your prop turns 9,000 rpm or higher, it might be OK. I'd like to hear some other opinions on this one.

Al
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Old Aug 24, 2007, 01:54 AM
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yikes!

I don't think you're gonna have enough jam there buddy...

I'm running a AXI 4130/16
6s 5000 mAh Thunder Power Extreme
Jeti 77
14X10 APC

I don't run it wide opoen but it's a very nice match...

Better to have too much than not enough...

Good Luck,

Sam
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Old Aug 24, 2007, 02:05 AM
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Ok, I re-evaluated it, and you're right, that doesn't add up... too much battery abuse.

Tracon's weigh doesn't match CMPs figures, I have yet to check my weight. So if CMPs numbers are miles away, this is all moot (I'll check when I get home). Tracon seems to be about 800g too heavy to make sense. My last CMP e-conversion (the Lancair) ended up half a kilo lighter than their lowest figure for glow.

However, I've tried out alternative motors in motocalc, and I think I see a pattern. If you make it heavier, the power consumption goes up (logically), and so it actually benefits from keeping the power set as light as you can.

So, I tried again from the motor (which I have and I'm trying to get away with using), and came up with 3s2p 2500 (packs I have) and a 12x8, which should give OK performance (I'm not looking to 3D this thing, nor pylon race it). I could also go with 5s1p 3700 (which I also have) and a 9x5 or 9x6, which would perform somewhat better... but that's going to be pulling 16 or 17000 RPM static!

It seems that going to 3300mAh 3s would be the sweet spot... I actually have one of those (but only one), so I might try that as well. Oh, the predicted static prop RPMs are around 8500, unloading to nearly 10k in flight.

So, opinions: 5s 3700, 9x6, 16000 RPM static, 45A for 770W in, or 3s2p2500, 12x8, 8500 RPM static, 55A for 582W in?

Actually, that looks like a no-brainer... 5s looks good. It's going to howl!
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Old Aug 24, 2007, 03:30 AM
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I'm just slightly over 9 lbs
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Old Aug 24, 2007, 03:47 AM
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USA, HI, Honolulu
Joined Jan 2003
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Quote:
Originally Posted by Andrew McGregor
Ok, I re-evaluated it, and you're right, that doesn't add up... too much battery abuse.

Tracon's weigh doesn't match CMPs figures, I have yet to check my weight. So if CMPs numbers are miles away, this is all moot (I'll check when I get home). Tracon seems to be about 800g too heavy to make sense. My last CMP e-conversion (the Lancair) ended up half a kilo lighter than their lowest figure for glow.

However, I've tried out alternative motors in motocalc, and I think I see a pattern. If you make it heavier, the power consumption goes up (logically), and so it actually benefits from keeping the power set as light as you can.

So, I tried again from the motor (which I have and I'm trying to get away with using), and came up with 3s2p 2500 (packs I have) and a 12x8, which should give OK performance (I'm not looking to 3D this thing, nor pylon race it). I could also go with 5s1p 3700 (which I also have) and a 9x5 or 9x6, which would perform somewhat better... but that's going to be pulling 16 or 17000 RPM static!

It seems that going to 3300mAh 3s would be the sweet spot... I actually have one of those (but only one), so I might try that as well. Oh, the predicted static prop RPMs are around 8500, unloading to nearly 10k in flight.

So, opinions: 5s 3700, 9x6, 16000 RPM static, 45A for 770W in, or 3s2p2500, 12x8, 8500 RPM static, 55A for 582W in?

Actually, that looks like a no-brainer... 5s looks good. It's going to howl!
Sam's power setup is what I was using in my .60 H9 Miss America flying at about 9lbs. For this plane you could do with a 4120 series motor with 4S 3850mah packs or something in that range to keep the weight down but sacrifice flying time.
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Old Aug 24, 2007, 04:06 AM
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Ok, just weighed all my parts. I come in at 2719g empty, or 3413g with 5s pack and everything installed.

Tracon, where did you find another 650g?
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Old Aug 25, 2007, 02:27 AM
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I added 6 oz of lead to get her to balance, my 6s 5000 battery weighs 726g

The AXI motor and the batter weigh in at about 2 lbs !!!

I know it's heavy, but it flies like a dream with lots of power..

Sam
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Old Aug 25, 2007, 05:53 AM
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Christchurch, New Zealand
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Well, I plugged the numbers into FSOne's scaling wizard, and FSOne thinks it will fly, and fly well. So, I think I'm going for it tomorrow. Wish me luck.

Edit: nope, not tomorrow. I can't get to CG without a huge lump of something in the nose... but that may as well be battery. I just have to figure out how to get it in there.
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Old Aug 25, 2007, 01:16 PM
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Good Luck on your maiden...

I added 6 oz of lead...

Ya gotta do what ya gotta do...



Sam
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Old Aug 25, 2007, 09:35 PM
One cell short of a Pack
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Good ole Smithsburg, MD
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Guys, what is the empty weight (no Motor, ESC or battery)

Nice model, I hope to get one myself!
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Old Aug 26, 2007, 01:43 AM
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Empty weight is 2720 grams. I'm not sure yet if it is possible to get it to balance with a motor as light as the 3025 without adding nose weight... it might take too much out of the firewall getting the big 5-cell inside the cowl. If I had a 3025-12 I could run that on 6-cell A123 and build a pack to fit inside the cowl. I may yet do that.
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Old Aug 26, 2007, 08:05 AM
One cell short of a Pack
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Dang that is heavy for a 65" wingspan!
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Old Aug 26, 2007, 08:33 AM
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It has flaps, so no big deal. But that does also help explain why the Robart strut is a good addition.
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Old Aug 26, 2007, 08:51 AM
One cell short of a Pack
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Good ole Smithsburg, MD
Joined Mar 2007
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Quote:
Originally Posted by Andrew McGregor
I'm not sure yet if it is possible to get it to balance with a motor as light as the 3025 without adding nose weight... If I had a 3025-12 I could run that on 6-cell A123 and build a pack to fit inside the cowl. I may yet do that.
I'm with you on that. I'll probly go with M1's (A123) myself. Probably need to re-enforce the firewall and then make a pass-thru in the lower portion. I figure if I can get it to balance with the battery pack, I'll just charge with the batteries still in the airframe.
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