Espritmodel.com Telemetry Radio
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Old Aug 23, 2012, 05:15 PM
dbc
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United States, FL, Brooksville
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Quote:
Originally Posted by eckace1 View Post
Another important observation: the battery pack and ESC both come down too warm.

Was it warm or hot warm is ok but hot not so much.
Could you hold it for more than 10 sec or even better an IR temp reading.
There are people who stick the esc on the outside of the fuse for cooling on the EZ threads.
It was "too warm" as stated. Maybe could hold the ESC for a few seconds but 10 doubtful. This is with mostly powered flight.
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Old Aug 23, 2012, 05:21 PM
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How are you guys measuring the CG location, running a string from the leading edge that curves with the wing? or a straight line perpindicular to the vertical line from the leading edge?

A or B method?
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Old Aug 23, 2012, 05:34 PM
dbc
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"B". Nice graphic, BTW.
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Old Aug 23, 2012, 05:38 PM
dbc
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Quote:
Originally Posted by eckace1 View Post
There are people who stick the esc on the outside of the fuse for cooling on the EZ threads.
A fine testament to how poorly designed some of these planes are.
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Old Aug 23, 2012, 05:38 PM
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ms paint to the rescue.
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Old Aug 23, 2012, 07:14 PM
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Originally Posted by dbc View Post
My measurements on the stock prop came in close to Blaser's. This with a new, fully charged 3600 3s 20c. Power draw: 310 watts, 25.5 amps. Prop RPM 12360. Actual measured thrust: 1320g. Calculated data: pitch speed 74 mph, thrust 1331g.

APC 9x6 prop gave 418 watts, 34.7 amps. Way over the recommended max. An APC 8x6 gave similar performance to the stock prop. APC makes an 8x8 but I dont have one in the prop box. It might give an improvement over the stock and still remain with the spec's.

The stock prop is going to be very close to optimum for this power system and it's the one I'll use initially.
Way over recommended max by who?

Will it blow the motor or esc with a 9x6?

I need quick climbouts for emergency overshoots on my landing strip...
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Old Aug 23, 2012, 07:21 PM
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Originally Posted by compuatic View Post
I'm at the recommended 100mm now and am batting a porpoising issue. A little bit of down stick and the plane immediately wants to climb back up. It is also difficult to keep it pointing straight, constantly wanting to turn. it seems like I'm constantly fiddling with the elevator trim.

Power off gliding is very slow and graceful with no stall tendency, and so I'm leaning to it being nose heavy rather than tail...but then again, the constant wanting to turn makes me wonder if it's tail heavy...ideas? the area i fly in is also quite windy, so it may just be the wind. hard to judge.

Had another uneventful 20 min fpv flight today.
It seems like the plane is tail heavy because it tries to pitch up by itself. The CG might be too far from the Center of Lift (located at 1/4 of chord), creating a moment that pitches the plane upwards. The slow, easy gliding reflects this too. As there is a moment trying to pitch the plane up, the angle of attack is high, thus creating more lift at low speeds. The high angle of attack creates more induced drag, which slows the plane down when gliding.

Regarding the rolling, the wind will try to roll the plane, as this plane has a huge tail.

How are you measuring the CG?

It would be great to see the FPV videos!
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Old Aug 23, 2012, 07:29 PM
dbc
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The motor spec sheet that comes with the plane specifies maximum amps: 29/20sec. Lipo cells: 3 Maximum efficient current 26-28 amps.

The supplied spec sheet on the ESC: lipo: 2-3 cells

I tried several different props and there's little that can be done to improve performance and remain within the limits perscribed by the equipment manufacturer. If you choose to overdrive it. You do so AYOR. I stated earlier that an APC 8x8 thin electric might provide a little extra performance and remain within specs. I did not have that particular prop so I'm not sure. An APC 8x6 drew slightly less power than the stock prop.

If you need quick climbouts you'll need a different motor - and probably an ESC capable of handling more current.
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Old Aug 23, 2012, 07:48 PM
dbc
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A motor like this can swing the 9x6 prop with good power on 4s. Looks like it would draw a little over 500 watts. It's about the same size but slightly lighter than the supplied motor. You'd need to upgrade to a 4s capable esc as well.

http://www.headsuprc.com/servlet/the...5-Sport/Detail
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Old Aug 23, 2012, 08:00 PM
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The 12360 RPM is measured with a digital tachometer on the stock power system at full power static. That's not "no load rpm."

And the power measurements were performed with a wattsup meter.

That 600 watt 1300kv motor would be a big upgrade and help in the balancing as well.

You might want to fly the plane with the stock power system before deciding about an upgrade.
The computed 59watts/lb sounds scary but, in actual practice, the plane flys pretty well.
As I've said before: stats give and idea but don't always tell the whole story.
Do you have a link to the motor?
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Old Aug 23, 2012, 08:04 PM
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Originally Posted by dbc View Post
A fine testament to how poorly designed some of these planes are.
That is a multiplex plane that cost $80 and zero electrinics Easystar1.
I have one and no I don't have the esc out of the fuse but it has about 250watts and weighs 26oz.
I'm going to look at the sss and find a combination that will give me 100w per lb.
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Old Aug 23, 2012, 08:08 PM
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Does one hand launch this or fly it off the ground?

I'm reading what all of y'all are saying about this plane and it seems to be a big, fuzzy Saint Barnard. It's a dog a really big dog!

If it wasn't for the short tail boom and what that might mean my thoughts would be wait and watch the board mod this thing and test it until I'm ready to buy the airframe and follow your list.

The Idea that this would be a good camera platform is a vision of the seller, observation of the obvious, watch the film.

DJ
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Old Aug 23, 2012, 08:10 PM
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Originally Posted by ariveroll View Post
Do you have a link to the motor?
http://www.gobrushless.com/shop/inde...ef=MD2510-1300

And he has the best warranty in the world.

Most of you will freak at the price though but its well worth the $

I also have one of his 2505 2800kv motors that I run at about 400 watts and it weighs in at a whopping 29 grams.
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Old Aug 23, 2012, 08:22 PM
dbc
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Originally Posted by eckace1 View Post
I'm going to look at the sss and find a combination that will give me 100w per lb.
I just gave you one - and it only costs $26.
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Old Aug 23, 2012, 08:25 PM
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Des Moines IA
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Originally Posted by dbc View Post
A motor like this can swing the 9x6 prop with good power on 4s. Looks like it would draw a little over 500 watts. It's about the same size but slightly lighter than the supplied motor. You'd need to upgrade to a 4s capable esc as well.

http://www.headsuprc.com/servlet/the...5-Sport/Detail
My thinking is the stock motor might be able to handle the 4s setup but testing will determin that.
I wont be able to test untill Mon but after that let the fun begin.
We have a cc50ice esc and also a ubec for the stock esc .
Was also woundering what the largest size prop that will fit without cutting the boom.
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