HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old May 05, 2011, 06:15 AM
Registered User
Vienna, Austria
Joined Apr 2007
1,878 Posts
Quote:
Originally Posted by Jurgen Heilig View Post
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
Hi Jürgen, I agree that the 8x7 folder would be much better (in the SEFF videos there I see APC props though - could be the 8x8 and then it would make sense), in my last post I also commented that the prop airfoil might allow a plane to reach the theoretical pitch speed, and I also agree that good high C batteries might even provide 11,5 V under considerable load when they are full - but just like tdriedger before you also calculate pitch speed as if the motor experiences no load (idle speed at 11,5V) - see my last post.
I do not doubt that the recommended motor at 600W+ would get the Dogfighter up to around 100mph level with the right prop.
cheers
Clemens
mopetista is online now Find More Posts by mopetista
Last edited by mopetista; May 06, 2011 at 06:47 AM.
Reply With Quote
Sign up now
to remove ads between posts
Old May 05, 2011, 06:52 AM
Registered User
Jurgen Heilig's Avatar
53859 Niederkassel, Germany
Joined Sep 2000
18,758 Posts
Quote:
Originally Posted by mopetista View Post
...
you also calculate pitch speed as if the motor experiences no load (idle speed at 11,5V) - see my last post.
...
Hi Clemens,

I know that this is very simplified, but I am pretty sure that the motor will get to such speeds and hold them in a horizontal line - at least for a while.

I am sure MPX checked their speed claims with telemetry.

Jürgen
Jurgen Heilig is offline Find More Posts by Jurgen Heilig
RCG Plus Member
Latest blog entry: InterModellBau 2014
Reply With Quote
Old May 05, 2011, 10:12 AM
WCRC Skyhawks
Greenville, SC
Joined Jul 2008
43 Posts
This is a theoretical (no-load) approach, you should consider a rpm drop under load (factor ~0.8 to be safe) => 82mph


Quote:
Originally Posted by Jurgen Heilig View Post
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
Xelerator is offline Find More Posts by Xelerator
Reply With Quote
Old May 05, 2011, 02:20 PM
Hitec/Multiplex USA
San Diego
Joined Dec 2005
156 Posts
We flew it with the 1350 KV Motor on the 10x7 Prop at SEFF. According to the GPS we got a ground Speed of 103 MPH with no wind. The battery was a TP 65C 2700Mah 3S.

There is a pretty good chance the 1350 KV motor and 10x7 prop end up being the final specs for the U.S. Power package.

On the windiest of days we recorded a Ground Speed of 133Mph and yes it was blowing at about 30mph.

Shawn
sspiker is online now Find More Posts by sspiker
Reply With Quote
Old May 05, 2011, 03:06 PM
Registered User
USA, CA, San Carlos
Joined Apr 2003
414 Posts
Quote:
Originally Posted by sspiker View Post
We flew it with the 1350 KV Motor on the 10x7 Prop at SEFF. According to the GPS we got a ground Speed of 103 MPH with no wind. The battery was a TP 65C 2700Mah 3S.

There is a pretty good chance the 1350 KV motor and 10x7 prop end up being the final specs for the U.S. Power package.

On the windiest of days we recorded a Ground Speed of 133Mph and yes it was blowing at about 30mph.

Shawn
At least now we have some numbers that make some sense...

11.5v x 1350kv = 15525rpm @ 7in pitch = 102.9 mph pitch speed

I'll let someone else comment on airframe drag, motor efficiency, and prop unloading.
tdriedger is offline Find More Posts by tdriedger
Reply With Quote
Old May 06, 2011, 12:06 AM
Registered User
Jurgen Heilig's Avatar
53859 Niederkassel, Germany
Joined Sep 2000
18,758 Posts
Quote:
Originally Posted by tdriedger View Post
At least now we have some numbers that make some sense...

11.5v x 1350kv = 15525rpm @ 7in pitch = 102.9 mph pitch speed
...
Actually, I had already posted those figures here:

http://www.rcgroups.com/forums/showp...4&postcount=90

And the chances are much higher to reach those rpm figures with an 8x7" rather than a 10x7" prop.

Jürgen
Jurgen Heilig is offline Find More Posts by Jurgen Heilig
RCG Plus Member
Latest blog entry: InterModellBau 2014
Reply With Quote
Old May 06, 2011, 01:24 AM
Registered User
restlessswind's Avatar
United States, CA, Sacramento
Joined Jan 2010
3,035 Posts
Can't wait for the dogfighter!



here are some quick imperial conversions:

25.4mm = 1"
12" = 1'(foot)
5280' = 1 mi

Think that is retarded? At least we don't use Rods, Furlongs, Fathoms, Chains and Links anymore!
restlessswind is offline Find More Posts by restlessswind
Last edited by restlessswind; May 06, 2011 at 01:37 AM.
Reply With Quote
Old May 09, 2011, 05:12 PM
Registered User
Vienna, Austria
Joined Apr 2007
1,878 Posts
What the Dogfighter will look like in the air

- similar to the Midget Mustang I would think

Thanks to J Barnes for the great video of the Midget Mustang. The Dogfighter videos lack this feel of speed but with the right setup the experience should be similar

PlaneAdrenalinRC's Mini-Midget Mustang (5 min 56 sec)


If I wanted to sell a plane I'd get some good videos done - but that's just me, I am no marketing buff, probably they know better at Multiplex

cheers
Clemens
mopetista is online now Find More Posts by mopetista
Reply With Quote
Old May 17, 2011, 11:10 AM
JOHN 3:16
Sammy70's Avatar
Central Ohio
Joined Feb 2008
6,206 Posts
So is this thing coming to the USA this year, or.........?


Do we know the price yet?
Sammy70 is offline Find More Posts by Sammy70
Reply With Quote
Old May 17, 2011, 02:22 PM
Editor - Flying Models
United States, CT
Joined Aug 2003
2,375 Posts
yes
$129.99
Thayer is offline Find More Posts by Thayer
Reply With Quote
Old May 17, 2011, 04:27 PM
Registered User
MRGTX's Avatar
United States, CT
Joined Aug 2005
1,929 Posts
Quote:
Originally Posted by Thayer View Post
yes
$129.99
Sounds about right...kit only, of course.
If it wasn't MPX we would tell them to pound sand.

Any dates yet?
MRGTX is offline Find More Posts by MRGTX
Reply With Quote
Old May 23, 2011, 11:47 PM
Registered User
Jurgen Heilig's Avatar
53859 Niederkassel, Germany
Joined Sep 2000
18,758 Posts
Dogfighter in Action ...

video from last weekend:

FMC Dietzenbach 2011 - Multiplex DogFighter (3 min 50 sec)


Jürgen
Jurgen Heilig is offline Find More Posts by Jurgen Heilig
RCG Plus Member
Latest blog entry: InterModellBau 2014
Reply With Quote
Old May 24, 2011, 03:44 AM
lud
Making mischief in the air
lud's Avatar
Berkshire UK
Joined Jan 2008
901 Posts
thats more like it . good video !

looking forward to getting mine now (the waiting is the worst part huh)

- looks like it also has good slow speed manners as well ..
lud is offline Find More Posts by lud
Reply With Quote
Old May 24, 2011, 03:52 AM
Registered User
perttime's Avatar
Tampere, Finland
Joined Nov 2004
4,186 Posts
It does look good, whatever the top speed is exactly. Sounds OK too. What did that one have for power?
perttime is online now Find More Posts by perttime
Reply With Quote
Old May 24, 2011, 03:58 AM
Registered User
Jurgen Heilig's Avatar
53859 Niederkassel, Germany
Joined Sep 2000
18,758 Posts
Quote:
Originally Posted by perttime View Post
It does look good, whatever the top speed is exactly. Sounds OK too. What did that one have for power?
MPX Dogfighter Ultra Li-Batt Set.

Jürgen
Jurgen Heilig is offline Find More Posts by Jurgen Heilig
RCG Plus Member
Latest blog entry: InterModellBau 2014
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Question Kyosho Phantom Reno Racer Motor Selection Cincy E-Flyer High Performance 6 Aug 12, 2011 03:35 PM
Discussion Multiplex news 2011: Reno-style DOGFIGHTER etc mopetista Foamies (Kits) 0 Feb 01, 2011 06:09 AM
Sold Cox Corsair II Reno Racer CL RTF skylane42 Aircraft - Fuel - Airplanes (FS/W) 0 Dec 11, 2010 10:45 AM
For Sale Hacker Reno Racer-Cosmic Wind Doug Hinkel Aircraft - Electric - Airplanes (FS/W) 1 Sep 02, 2010 01:02 PM