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Old Oct 25, 2006, 12:33 PM
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Jurgen Heilig's Avatar
53859 Niederkassel, Germany
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Quote:
Originally Posted by jernejk
That helps me choosing my battery pack, thanks. How about 2500mAh weighting 209g? Is that ok or will that also lead to CG problems? The next option is 2150mAh weighting 178g - but I'd prefer 2500 to be on the safe side regarding high current.

Jernej
I use a Hacker Evo 20 (FlightPower) 3s2500mAh pack (209g) - and I am happy with it.

Jürgen
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Old Oct 25, 2006, 12:37 PM
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53859 Niederkassel, Germany
Joined Sep 2000
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Quote:
Originally Posted by Jeremy Z
...
I like a heavy battery because I find that it helps the plane penetrate the wind a bit better...
Actually, the less weight, the lower the required AOA (= less drag) in horizontal flight. If you take two identical models with the same power, the lighter model will fly slower and faster. The faster model will penetrate the wind better.

Jürgen
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Old Oct 25, 2006, 12:40 PM
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Quote:
Originally Posted by mjws
...
The video posted with Martin flying inside was on a 3516. I'm assuming he tried the 2808/24 and maybe a lighter pack and was unimpressed. Is that right Jurgen?
...
Mike
Hi Mike,

I don't know for sure which motor he had in for the Indoor maiden, but it was an AXI with 4mm shaft and the motor weight was approx. 100g.

Jürgen
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Old Oct 25, 2006, 12:46 PM
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53859 Niederkassel, Germany
Joined Sep 2000
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Quote:
Originally Posted by resedaguy
thanks Jurgen,
BEC is working as I have control, but thought maybe it was cutting out the motor to keep enough voltage for servo operation.
I'll try changing the Cutoff votage from LIPO AUTODetect to the next lowest setting of 4.0 V and see if that helps any.
Don't do this. Your problem is not the cutoff voltage, but the cutoff type.

The CC45 comes with hard cutoff as standard. You want to change that into soft cutoff.

Check the settings of your ESC:

9.1 Cutoff voltage: 9V
9.2 Current Limiting: Option 3 = Standard
9.3 Brake type: Option 5 = Brake disabled
9.4 Throttle type: Option 1 or 2
9.5 Timing: Option 1
9.6 Cutoff Type: Option 2 = Soft cutoff
9.7 Soft Start: Option 2 or 3
9.8 PWM Switching rate: Option 1 or 2

Check here: http://www.castlecreations.com/suppo...er%20Guide.pdf

Jürgen
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Old Oct 25, 2006, 01:46 PM
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Kranj
Joined Jun 2006
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Quote:
Originally Posted by Jurgen Heilig
I use a Hacker Evo 20 (FlightPower) 3s2500mAh pack (209g) - and I am happy with it.

Jürgen
Thanks!

Jernej
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Old Oct 25, 2006, 02:42 PM
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Northern IL
Joined Oct 2005
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Quote:
Originally Posted by Jurgen Heilig
Actually, the less weight, the lower the required AOA (= less drag) in horizontal flight. If you take two identical models with the same power, the lighter model will fly slower and faster. The faster model will penetrate the wind better.
I believe you, but it sure doesn't seem like it from experience. A perfect example is my EasyStar vs. TwinStar 2. They have about the same wingspan and the EasyStar is more aerodynamic than the TwinStar. But the TwinStar has a LOT more weight, and it doesn't get tossed around as easily.

What you're saying makes sense if there are no gusts. But when a gust comes along and blows against my plane, the lighter plane has less inertia, and it slows down more.

Aren't jetliners better flyers in the wind than a two seat passenger airplane, even if the smaller, lighter and faster plane is a jet?

It is because the the wind seems stronger to the smaller plane. It is the same with boats. The smaller boats aren't ocean-worthy, because the same wave affects the smaller & lighter boat to a much larger extent.

I'm not the only one who finds that a heavier, more highly-wing loaded plane handles the wind better.
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Old Oct 25, 2006, 03:00 PM
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53859 Niederkassel, Germany
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Quote:
Originally Posted by Jeremy Z
...
I'm not the only one who finds that a heavier, more highly-wing loaded plane handles the wind better.
A model with a higher wing loading will give you a smoother ride in bumpy conditions, but you were talking about penetrating wind. The lighter model with the same motor is faster and it also has a bigger safety margin when it comes to stalling.

Jürgen
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Old Oct 25, 2006, 03:23 PM
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United States, CA, North Highlands
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Sailplanes are where more weight will help you penetrate wind better. Inertia is the key there.
Jurgen's correct about powered planes though. Different ballgame altogether.

Brian
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Old Oct 25, 2006, 03:39 PM
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Tenerife,Canary Islands
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You should take like this:

More weigtht needs more lift , more angle of attack then more drag . Lighter is faster.

In gliders is essentially the same between a certain angle of attack , lowering this angle does´nt make the drag less but makes you sink , now you need ballast to stay in good range .Note that gliders are always going down ...... until the air goes up

Cheers..
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Old Oct 25, 2006, 06:42 PM
all thumbs
Upstate NY, USA
Joined Dec 2005
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That illustrates a significant distinction, chichisport: Full-scale gliders are often ballasted down for faster cross-country flight between thermals, which moves their best lift/drag (optimal Angle of Attack/"AoA") airspeed numbers higher. Although a ballasted glider does sink at a slightly higher vertical speed, it is also moving forward at a significantly higher best-glide airspeed. But that's not the only way that a ballasted glider is more efficient on windy days.. With ballast, gliders become more efficient in turbulence, because stored kinetic energy evens out the bumps of rough air, in a similar way as a loaded car "rides" more softly over the road.

Jürgen is right that low gross weight means a lower AoA for level flight, and that a lighter plane enjoys a generally wider flight envelope (including a higher maximum level speed). But what it means to "penetrate the wind" is a bit subjective. For me as a glider pilot, wind penetration includes how the glider responds to variable winds. I'm no "3-D" pilot yet, and certainly not on windy days. But I do prefer slightly heavier models (and full-scale aircraft) when it's windy.

A slightly heavier battery means that the model is more ballistically stable in windy conditions than it would be at a lighter weight; momentum places it a little less at the mercy of the wind. Somewhat counterintuitively, it also means that the structural stresses are lower when flying heavier: Accelerations due to turbulence are reduced, and level-flight operation closer to stalling AoA lowers the maximum loading the wing can produce in a "gust" (blast of air from head-on or below).
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Old Oct 25, 2006, 06:59 PM
SD_Raptor
San Deigo, CA
Joined Mar 2006
685 Posts
New candidate motor for the AM

I have located a new candidate motor for the AM. It is the Hyperion HP Z3013-16. The Z-3007 series is also a candidate but the WOT power is down toward the lower end of where I would like. The specs for the 3013-16 (from allerc.com) are

HP-Z3013-16
Weight g 110, Outside Diameter mm 37, Length mm 37.8, Output Shaft Diameter mm 5, Max eff. Current A 17-27, Peak current A 36A 60sec, LiPo cells 2~4, Resistance Ohm 0.040, Io A 2.0, KV rpm/V 985

Oh yeah, price $79.95 retail.

Its mate the 3016-14 also looks like a reasonable match. I bought the -16 since they had one in stock at LHS and will try it out tomorrow. Report to follow.

The Dualsky X-motor I am now using weighs in at 165 grams, so I'll be shaving off 55 grams with the new motor and not sacrificing any performance on a 3s pack, perhaps gaining a bit of endurance.

The HP Z3013-16 also has a different shape which moves the CG of the motor back several mm compared to the X-Motor. This should allow me to either use a larger battery pack than I could before or have more flexibility in positioning the pack.

If the Z3013-16 works better than the X-Motor, I guess I'll just have to find a plane for the X-Motor to fly. Maybe it is time for a nice warbird.....

Randy
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Old Oct 25, 2006, 11:32 PM
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Quote:
Originally Posted by SD_Raptor
...
HP-Z3013-16
Weight g 110, Outside Diameter mm 37, Length mm 37.8, Output Shaft Diameter mm 5, Max eff. Current A 17-27, Peak current A 36A 60sec, LiPo cells 2~4, Resistance Ohm 0.040, Io A 2.0, KV rpm/V 985
...
The HP Z3013-16 also has a different shape which moves the CG of the motor back several mm compared to the X-Motor.
...
Randy
Hi Randy,

With such a light motor, you may get into trouble achieving the correct CofG. It is much easier to move the battery pack further back, then further forward.

As the motor is also "softer" than the Himax, you may want to use a 12x6" instead of an 11x5.5".

Jürgen
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Old Oct 26, 2006, 02:12 AM
SD_Raptor
San Deigo, CA
Joined Mar 2006
685 Posts
Hyperion Motor

Quote:
Originally Posted by Jurgen Heilig
Hi Randy,

With such a light motor, you may get into trouble achieving the correct CofG. It is much easier to move the battery pack further back, then further forward.

As the motor is also "softer" than the Himax, you may want to use a 12x6" instead of an 11x5.5".

Jürgen
Jurgen,

I just checked the CoG, it is good with a 4s2000 Kokam battery about mid-point in the battery compartment. So a 3s2500 battery would also work well. This CoG test was without the aluminum spinner for the Graupner collet type prop adapter I am using: adding the spinner will also help move the CoG forward a bit. I will try it all out with 11x7E, 12x6E, 12x6SF, 13x6.5E and 13x6.5SF props and perhaps with a 3-blade 11x7 Graupner that I have used on my Magister (that prop alone will add enough mass to move the CoG far forward).

Any thoughts on the advantages/disadvantages of SF props versus E props?

The previous heavy motor and light 3s 1700 mA-Hr Lipo could not produce good sustained vertical - low voltage cutoff always kicked in at WOT.

I plan to use the AM as my practice plane before putting my much more expensive Hyperion Yak-54 up each flying day. I am sure that the AM will be more forgiving than the big Yak.

A neighbor down the street has offered to sell me his 84 inch (2.1 meter)wingspan Edge 540 that he has flown only twice on a DA-50 gas engine. The plane with engine weighs only 14 lbs (6.5kg) so it would be a great candidate for conversion to electric - the ultimate ARF - just add motor, ESC, and batts . But for that size, the cost of motor, ESC and batts will be substantial.

Another motor option for the AM is the Neu Motor 1107/2Y with 4.4:1 gear box. It computes out with just a bit less thrust that I expect from the Hyperion motor but has effeciency over 90%. The downside is that the motor/gearbox combo costs $180.

Randy
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Old Oct 26, 2006, 02:35 AM
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ModelTony's Avatar
Irvine, Scotland
Joined Jun 2004
636 Posts
Quote:
Originally Posted by SD_Raptor
Jurgen,

I just checked the CoG, it is good with a 4s2000 Kokam battery about mid-point in the battery compartment. So a 3s2500 battery would also work well. This CoG test was without the aluminum spinner for the Graupner collet type prop adapter I am using: adding the spinner will also help move the CoG forward a bit. I will try it all out with 11x7E, 12x6E, 12x6SF, 13x6.5E and 13x6.5SF props and perhaps with a 3-blade 11x7 Graupner that I have used on my Magister (that prop alone will add enough mass to move the CoG far forward).

Any thoughts on the advantages/disadvantages of SF props versus E props?

The previous heavy motor and light 3s 1700 mA-Hr Lipo could not produce good sustained vertical - low voltage cutoff always kicked in at WOT.

I plan to use the AM as my practice plane before putting my much more expensive Hyperion Yak-54 up each flying day. I am sure that the AM will be more forgiving than the big Yak.

A neighbor down the street has offered to sell me his 84 inch (2.1 meter)wingspan Edge 540 that he has flown only twice on a DA-50 gas engine. The plane with engine weighs only 14 lbs (6.5kg) so it would be a great candidate for conversion to electric - the ultimate ARF - just add motor, ESC, and batts . But for that size, the cost of motor, ESC and batts will be substantial.

Another motor option for the AM is the Neu Motor 1107/2Y with 4.4:1 gear box. It computes out with just a bit less thrust that I expect from the Hyperion motor but has effeciency over 90%. The downside is that the motor/gearbox combo costs $180.

Randy
Good information on the Hyperion series of motors is available at the Aircraft-World site.

Ref the big beastie at 14lb you should be looking for about 2100watts.

http://www.aircraft-world.com/prod_d...z50/z50all.htm

Tony
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Old Oct 26, 2006, 02:35 AM
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Aberystwyth, UK
Joined Sep 2004
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Quote:
Originally Posted by SD_Raptor
A neighbor down the street has offered to sell me his 84 inch (2.1 meter)wingspan Edge 540 that he has flown only twice on a DA-50 gas engine. The plane with engine weighs only 14 lbs (6.5kg) so it would be a great candidate for conversion to electric - the ultimate ARF - just add motor, ESC, and batts . But for that size, the cost of motor, ESC and batts will be substantial.

Randy
Believe me. Your talking big money to convert that plane. The motor and ESC would be peanuts compared to the battery you would need to fly it

If its got a DA-50, it would be a crime to strip that beauty out.

Mark
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