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Old Apr 28, 2011, 08:26 AM
Did you get it on video?
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Dogfighter segment starts around 1:23

Flite Test - 02 SEFF 2011 - EVENT (12 min 1 sec)
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Old Apr 28, 2011, 04:55 PM
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Am I reading correctly, you got her over 100mph with the motor/esc you will get with the stock setup, not some upgrade package right?

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Originally Posted by Brian Chitty View Post
Here is some DogFighter Footage shot at the SEFF event a few weeks ago. I personally flew it and a blast. This is going to be a fun pylon racer! We even got her up to 113 mph on a level pass with the standard power pack setup!
http://www.youtube.com/watch?v=YErlA...el_video_title
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Old Apr 28, 2011, 06:02 PM
Did you get it on video?
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That's what the rep said.
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Old Apr 28, 2011, 06:59 PM
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Quote:
Originally Posted by Brian Chitty View Post
Here is some DogFighter Footage shot at the SEFF event a few weeks ago. I personally flew it and a blast. This is going to be a fun pylon racer! We even got her up to 113 mph on a level pass with the standard power pack setup!
Great to see that speed on a plane that will make much less noise than an EDF or pusher going over 100 mph.
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Old Apr 29, 2011, 07:05 AM
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Yes, Over a 100 for sure. This is not a "hot" setup. I'm sure people will have these airframes blazing much faster with more Kv rated motors and higher cell count batteries.
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Old Apr 29, 2011, 10:24 AM
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Vienna, Austria
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Quote:
Originally Posted by msev View Post
Am I reading correctly, you got her over 100mph with the motor/esc you will get with the stock setup, not some upgrade package right?
Again, I don't believe it is possible w/ the stock 9x6 prop, you just don't get the necessary pitch speed (stock 3s, 1350kV motor), but 8x8 might just do the trick
cheers
Clemens
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Old May 04, 2011, 11:57 AM
WCRC Skyhawks
Greenville, SC
Joined Jul 2008
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According to the data sheet:

The stock setup is called "DogFighter TUNING", 3S, 1130kv motor, 10x7prop, good for 90mph
The upgrade is called "DogFighter ULTRA", 3S, 1350kv motor, 9x6 prop, good for 103mph

Cheers,
Chris

Quote:
Originally Posted by mopetista View Post
Again, I don't believe it is possible w/ the stock 9x6 prop, you just don't get the necessary pitch speed (stock 3s, 1350kV motor), but 8x8 might just do the trick
cheers
Clemens
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Old May 04, 2011, 12:19 PM
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90mph is still good, at 89 euro in Schweighofer, Austria...
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Old May 04, 2011, 12:33 PM
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Quote:
Originally Posted by Xelerator View Post
According to the data sheet:
The stock setup is called "DogFighter TUNING", 3S, 1130kv motor, 10x7prop, good for 90mph
The upgrade is called "DogFighter ULTRA", 3S, 1350kv motor, 9x6 prop, good for 103mph
3S Lipo @ 10.5V I get the following pitch speeds:

Tuning - 78mph
Ultra - 80mph

100+ mph would need 4S with either of the suggested power setups.
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Old May 04, 2011, 03:37 PM
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Calculating pitch speed, and how to account for unloading

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Originally Posted by tdriedger View Post
3S Lipo @ 10.5V I get the following pitch speeds:
Tuning - 78mph
Ultra - 80mph
100+ mph would need 4S with either of the suggested power setups.
Your pitch speed calculation assumes a drop of voltage under load (whether 10,5V for 3s is a good estimate depends on the internal resistance of the battery and the amps, for 50+ amps and a regular 25C 2200mA battery that seems ok) but at the same time you take the idle rpm of the motor at that voltage. Even with a fair amount of unloading that is not realistic.

For those who want to know how to calculate pitch speed at certain rpm with a certain prop:

rpm = revolutions per minute. Each revolution propels the prop (theoretically) forward by the amount specified in the pitch (unsually inches)

So by multiplying rpm with the prop pitch you get the pitch speed in inches per minute. To get miles per hour you have to convert that first into miles (I don't know the exact conversion factor as I am "metric", it must be something like 40x1600 inches in a mile) and then multiply by 60 (in an hour you get 60 times as far as in one minute).
So that is the easy part.
tdriedger obviously put in 10,5 Volts times 1350 rev per Volt per minute times 6 inches per revolution and converted that (inches per minute) to miles per hour. Beware that the kV gives you the idle rpm per Volt...

A software such as drivecalc will also tell you how fast a certain motor will spin a certain prop using a certain battery. You see that a motor under load will spin the prop less fast than at idle w/out prop, typical is some 60-75%.
That gives you static pitch speed. What you have to guesstimate is the unloading in flight, i.e., the motor is revving more freely because the air is coming along nicely for the prop to shove behind. That depends on a host of factors, in well-designed setups which aim for high prop efficiency you get something like 20% unloading. If you use very high pitch props they will only unload in a steep dive but won't give you the maximum level speed. Conversely, if you choose a big prop with less pitch you will have plenty of static thrust which results in good acceleration, good vertical but limits your speed, and the prop acts as a brake even in a shallow dive.
Although in theory a plane will be slower than the pitch speed of the prop (since there should be no thrust to propel the plane if the prop's movement is just matching the speed of the incoming air) speeds can sometimes be as high as pitch speed due to prop airfoil lift effects - and the true pitch of a prop isn't always what's printed on it.
A dogfighter with those big props will see a lot of unloading in level flight since 9x6 or 10x7 would be chosen for maximum vertical acceleration. For speed you would want to use 8x8 or similar.
I hope we will soon see how fast this dogfighter really is. I wouldn't buy any of the MPX drive sets anyway, the good thing about the motor mount is that you can put in any 35mm motor from HK or other without the need to reverse the motor shaft or such.

cheers
Clemens
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Last edited by mopetista; May 04, 2011 at 03:48 PM.
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Old May 04, 2011, 04:58 PM
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I never said that the plane would go 80mph on 3S.

I completely agree with all your points. I simply ran some simple numbers to give the maximum pitch speed with no other losses. Someone with a better understanding of motocalc or similar program could better model performance and speed with 3S and 4S power.

What I believe my numbers do say is that there is no way in the recommended power systems will do over 100mph on any day of the week. Even in a perfect world.

I think 65-75mph is more realistic but I'll leave the scientific numbers to someone else.
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Old May 04, 2011, 05:02 PM
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Quote:
Originally Posted by Brian Chitty View Post
We even got her up to 113 mph on a level pass with the standard power pack setup!
Coincidentally...

113 km/h = 70.2149447 mph
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Last edited by tdriedger; May 04, 2011 at 06:32 PM.
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Old May 04, 2011, 06:18 PM
Pro Bro # 2398
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BoonVegas, Indiana
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thank you Jesus !
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Old May 04, 2011, 06:52 PM
Ozzie Express wiggy pilot
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YANKALILLA , SOUTH AUSTRALIA.
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No god was involved with the making of this plane.........
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Old May 05, 2011, 03:24 AM
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Quote:
Originally Posted by mopetista View Post
Again, I don't believe it is possible w/ the stock 9x6 prop, you just don't get the necessary pitch speed (stock 3s, 1350kV motor), but 8x8 might just do the trick
cheers
Clemens
Hi Clemens,

actually, some sleek models do reach the theroretical (geometrical) pitch speeds, because all those drive calculators never consider that the prop blades are profiled.

You are assuming that the top speed was reached with an 9x6", when the recommended folder is actually 8x7".

I would assume, that the voltage under load at top speed is closer to 11.5V than 10.5V.

11.5V x 1350U/V x 1/60 x 0.1778m (=7") = 46m/s = 165.6kph = 103mph

Jürgen
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