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Old Mar 22, 2006, 09:49 AM
Sureflite
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Joined Jan 2006
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He could just not have the right CG
If anything I am just guessing but, a 370 might be a 300size with the kick of a 400.
The permax 400 is a speed 400.
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Old Mar 22, 2006, 11:40 AM
SlopeHead
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Lisboa, Portugal
Joined Jan 2004
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Quote:
Originally Posted by TonyBAMF
He could just not have the right CG
If anything I am just guessing but, a 370 might be a 300size with the kick of a 400.
The permax 400 is a speed 400.
I think Jeremy has probably checked the CG correctly.

A 370 is a Mabuchi 370, AKA Speed 400. The Speed 400 and the Permax 400 have some differences, as they both are built, AFAIK, to Multiplex and Graupner's own specs. I can tell you the Permax 400 has built in condensers, which I think is not true of the Speed 400 (Graupner).

From Multiplex site:

Permax 400 6V
Dimensions: 27.5 Ø x 40.5 mm
Weight: 73 g
No-load speed: 17,400 rpm
No-load current drain: 0.7 A
Maximum current: 8 A
Current drain at max. efficiency: 3.5 A

From Graupner site:

No-load rpm 18000 min–1
No-load current drain 0,7 A
Current drain at max. efficiency 4 A
Current drain when stalled 25 A
Max. efficiency without gearbox 70 %
Length of case, excl. shaft 37,8 mm
Diameter 27,7 mm
Free shaft length 13,8 mm
Shaft diameter 2,3 mm
Weight 73 g


As you can see there are quite a few differences. Even the dimensions are not exactly the same.

BTW, notice the efficiency figures from Graupner? Those are measured, not calculated by some software guy... The Permax 400 is, at least, as efficient as the Speed 400. So those 30-40% efficiency claims by some less informed people are obviously wrong... Still, a brushless motor is typically more efficient, around 75-85% for an outrunner and above 85% for an inrunner. This of course for the good brushless motors(Axi, Electronic Models, Kontronik, Hacker, Lehner, Mega, Jeti, Plettenberg, etc), not some cheap chinese products going around with wild claims about performance and efficiency.
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Old Mar 22, 2006, 11:52 AM
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53859 Niederkassel, Germany
Joined Sep 2000
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Quote:
Originally Posted by Jeremy Z
Forgive my ignorance in brushed motor nomenclature. I thought they were the same? I remember reading somewhere that a 6V 370 motor is really a speed 400. Does that mean a speed 400 is a weaker motor than a permax 400 6V?
Speed 400 is the Graupner name for a Mabuchi RS380 motor, and I know some guys at Multiplex get upset when you call their Permax motors "Speed".

The Permax 400 and the Speed 400 were once the same motors, but Multiplex seems to have changed their supplier. If you play with EZ-Calc, you get pretty different figures for basically the same motor:

http://brantuas.com/ezcalc/dma1.asp

Try: Mpx Permax 400, 6V / Grp Speed 400, 6V / Robbe Power 400/35

Jürgen
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Old Mar 22, 2006, 11:55 AM
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Quote:
Originally Posted by jcosta
...
A 370 is a Mabuchi 370, AKA Speed 400. The Speed 400 and the Permax 400 have some differences, as they both are built, AFAIK, to Multiplex and Graupner's own specs. I can tell you the Permax 400 has built in condensers, which I think is not true of the Speed 400 (Graupner).
...
The Mabuchi 370 is actually a Speed 300.

All Graupner Speed 400 have integrated capacitors.

Jürgen
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Old Mar 22, 2006, 11:58 AM
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Quote:
Originally Posted by jcosta
...
BTW, notice the efficiency figures from Graupner? Those are measured, not calculated by some software guy...
...
These figures are manufacturer (Mabuchi) data - but the Mabuchi data are very precise.

Jürgen
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Old Mar 22, 2006, 12:02 PM
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Quote:
Originally Posted by Jeremy Z
...
Regarding the angle of attack comment: You said that if you climb at 20°, your AOA is only 5°. Does this mean the wing is angled down at 15°?
No, the model may climb at an angle of 20°, but the wing will be at an angle of approx. 25° measured to the horizon. At 5° AOA, a Clark Y type wing section will provide a lift coefficient of approx. 0.7.

Jürgen
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Old Mar 22, 2006, 12:14 PM
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Quote:
Originally Posted by Jeremy Z
...
- How much wind can it handle before it starts to make very slow progress for you? i.e. it takes a lot longer to fly upwind than downwind?...
Hi Jeremy,

perhaps you meant something like this?:

see attachment.

Jürgen
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Old Mar 22, 2006, 12:33 PM
SlopeHead
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Lisboa, Portugal
Joined Jan 2004
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Quote:
Originally Posted by Jurgen Heilig
The Mabuchi 370 is actually a Speed 300.

All Graupner Speed 400 have integrated capacitors.

Jürgen

Sorry, right, its the Mabuchi 380 that is the Speed 400..

And thanks for the info on the Graupner motors. My experience with Speed motors is limited to the 300Plus on my Mini Piper...
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Old Mar 22, 2006, 12:36 PM
SlopeHead
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Quote:
Originally Posted by Jurgen Heilig
These figures are manufacturer (Mabuchi) data - but the Mabuchi data are very precise.

Jürgen
Definitely more precise than Motocalc...
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Old Mar 22, 2006, 09:13 PM
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halifax nova scotia canada
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I finally got to fly my TS ll last weekend and I was really impressed with its performance. I let my buddy who has much more experience than me fly the plane for a bit and he was also impressed but thought the CG should be moved forward a bit. I am using 8 sub c 3300mah battery packs which weigh about 18 oz. The plane seemed to zoom up with the CG set at 85 mm. I was thinking of adding a little down elevator to keep the plane flying level when you add throttle. Other than that I was very pleased with the plane and can't wait till next weekend to fly it again. I would like to thank all the people on this site who helped me with their knowledge and experience and I will try to send some flight video. THE WALRUS
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Old Mar 22, 2006, 09:28 PM
Hold my beer and watch this!
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Thanks for the info Jürgen & jcosta!
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Old Mar 23, 2006, 04:08 AM
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Quote:
Originally Posted by THE WALRUS
I let my buddy who has much more experience than me fly the plane for a bit and he was also impressed but thought the CG should be moved forward a bit. I am using 8 sub c 3300mah battery packs which weigh about 18 oz. The plane seemed to zoom up with the CG set at 85 mm.
If you mean that when the plane speeds up it wants to climb excessively then you need to move the CG back, not forward.
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Old Mar 24, 2006, 06:32 AM
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Buffalo, NY
Joined Mar 2006
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Hello, all!

I just received my Twinstar II yesterday as my first foamy, second electric. Can't wait to get it airborne after watching all your videos. Looks like it flies great.

Unfortunately, my kit did not come with the circiut board. Does anyone know if I could just hardwire the motors to the ESC or does the board contain necessary components for proper current to the motors? I'll be using a completely stock system for now, with 7-8c NiMHs, 2500 to 3500mAh range, 30a max draw. The ESC is a GP C-35 brushed w/BEC.

Hopefully I can maiden it this weekend if I can bypass the board. Thanks for any advice you can give.
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Old Mar 24, 2006, 07:02 AM
Hold my beer and watch this!
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Northern IL
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Quote:
Originally Posted by 05raptor660r
Unfortunately, my kit did not come with the circiut board. Does anyone know if I could just hardwire the motors to the ESC or does the board contain necessary components for proper current to the motors?
The circuit board is just for convenience of removing/reattaching the wing.

After a few times doing this, the strands of wire of the aileron extension start to fray where they exit the board. You could just use another set of servo extensions to replace this and it would be better. You could just use Deans connectors to do the motors. Bullet connectors would work too, but take care to make sure they stay insulated and that they can't bang against something else in there.

After I did my brushless upgrade, I pulled those leads out of the wing anyhow. I've left the wing on ever since. It fits in my trunk just fine.
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Old Mar 24, 2006, 07:27 AM
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Joined Mar 2006
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Thanks for the good news!

I'll get a few Deans froms the LHS today. Hopefully it will be in the air by Sunday.

Lots of good info here. Thanks!
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