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Old Apr 29, 2011, 08:57 AM
Capt, USAF
Roswalt's Avatar
United States, NV, Las Vegas
Joined Feb 2009
922 Posts
I took this thing in the air yesterday:

Stock PNP set from BH, flown with a 40C battery and an AR6100 RX. Flew reasonably well, takeoff was pretty short - but I can say with 100% certainty that this is not a 3D plane. It is a sport model with good power and great aileron authority for some good looking axial rolls, and it flies pretty well under power. Visibility was incredible - The colors seem outrageous on the ground but they help a ton in the air. Vertical is possible for a spell, but is definitely not sustainable for very long.

The bad - Landings were very difficult for two reasons: huge tendency to nose over/tip stall that you must stay on top of the whole way through touchdown and full-stop- In no way will this airplane forgive less than perfect landings. Secondly, the wheel pants cause problems for touchdown and will get chewed up very quickly. I'll be pulling mine off.

It also exhibited some very strange rolling when throttle is brought up - Not the yaw typical of high-power props, but rather a sharp change in the roll axis under quick acceleration. If you are smooth you may not ever see this - I learned to keep it from happening through throttle management.

It's definitely a fun plane to fly but it is not at all what I thought it would be. I have two other planes in my hangar that fill this "good flyer with above average power" niche. This plane goes up for sale today, and hopefully it will be sold by Sunday. On to the next project!
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Old Apr 29, 2011, 09:02 AM
Crash & Burn
rmgmag's Avatar
Glastonbury, CT
Joined Nov 2004
2,502 Posts
Roswalt - did you use that stock 3-blade prop? I can't imagine that prop generating enough thrust to hover it.
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Old Apr 29, 2011, 09:03 AM
Capt, USAF
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United States, NV, Las Vegas
Joined Feb 2009
922 Posts
Yes, my intent was to fly it as advertised by BH, not as a modeler's-special. IMO you can make anything super-impressive if you pour enough money and time into making it that way.

I gave it a brief hover attempt but I don't see it as a viable maneuver out of the box.
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Old Apr 29, 2011, 09:11 AM
Crash & Burn
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Glastonbury, CT
Joined Nov 2004
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Roswalt - yep, I'd prefer a good flier right out of the box. I really don't want to spend a ton of money on a good power system. Might as well buy the Carbon-Z if that's the case.
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Old Apr 29, 2011, 09:30 AM
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Joined Jul 2007
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Thanks for your feedback Roswalt...
OMG I have juste ordered it yesterday (Europe version), for sure I will have to upgrade the propoulsion set as I would like to pratice 3D with this plane.
Roswalt, do you think it would be possible to hold torque roll with another propulsion set, or you think that this plane can't do that, whatever the motor (I can cancel order until tomorrow) ?
Thanks.
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Old Apr 29, 2011, 10:29 AM
Capt, USAF
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United States, NV, Las Vegas
Joined Feb 2009
922 Posts
No problem... I couldn't say what would happen with another propulsion set - As I mentioned earlier, this thing will scream with an F-15 Strike Eagle strapped to it, so everything is relative to what you're willing to try!

You won't be practicing full 3D with the plane as-is, but you may get some good practice to prepare for something with a better power-to-weight ratio. This MX2 is deceptively heavy thanks in part to all that dense EPO foam.
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Old Apr 29, 2011, 12:51 PM
Clear Lake near NASA
United States, TX, Houston
Joined Jul 2010
83 Posts
Quote:
Originally Posted by Roswalt View Post
This plane goes up for sale today, and hopefully it will be sold by Sunday. On to the next project!
I have sent you a PM with regard to the quote.
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Old Apr 29, 2011, 01:50 PM
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United States, KS, Topeka
Joined Mar 2005
1 Posts
Hello, where is the center of gravity for this plane? When I bought my mx2 the manual wasn't included unfortunately. I've been a rcgroups member since 2005 and never had to ask for information before, always found it through searching. Thanks.
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Old Apr 29, 2011, 07:06 PM
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United States, AZ, Tucson
Joined Nov 2007
870 Posts
the prop is very cool but all wrong for 3d. 12x9x3 the prop has to much pitch and being three blades it suffers from parasitic drag so its got 2 problems that reduce thrust. I would put a 14x7 on it and see what happens.
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Old May 04, 2011, 08:56 AM
Crash & Burn
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Glastonbury, CT
Joined Nov 2004
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Has anyone else flown this yet?
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Old May 04, 2011, 10:30 AM
Capt, USAF
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United States, NV, Las Vegas
Joined Feb 2009
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I revised mine a little bit and tried again - Results were very positive.

The wheel pants and all foam pieces up to the attachment point were removed - Believe it or not, there is an appreciable amount of weight loss from that operation due to the density of the EPO foam. Also, I took the gear assembly off and rebent it on a vice in order to get a better taxi/landing stance. This helped the landing phase immeasurably. Like a different plane, as a matter of fact. My advice, as it usually is - Lose the pants!

In flight, once you get past the fact that it won't be a 3DHS demon, it flies pretty well. Much more of a "regular" plane with pop though. Axial rolls were impressive but the elevator will flex in sharp loops, so that will need to be addressed if you aim to snap-loop a lot.

I reworked the ailerons to independent channels and assigned a flaperon function - This was helpful but probably not necessary. It needed a lot of elevator trim when deployed. Having independent ailerons can really help on a number of different levels though.

I reworked my own DX8 in order to fix the jittering servos and strange "axial torque roll" that I had seen exhibited before. I feel pretty confident that those issues were tied to radio glitching of some kind.

The MX2 is proving to be quite a solid performer that has merit - Just not for the advertised purpose. I had five great landings and no mishaps, just a little wingtip rash from a crosswind gust during taxi. I may keep it around as a test bed for future ideas, or I may follow through and sell it. This is a large plane and it does occupy a fair amount of space!
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Old May 04, 2011, 05:54 PM
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Joined Jul 2007
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Roswalt, what is the weight of your plane, with and without battery ?
I will receive mine tomorrow, I'm going to built it next week-end but I don't have my batteries, I only have 4000 4S batteries that I use for a Het RC F16, I think they are too heavy for this plane, I have to wait the plane to order new batteries as I dont' know the size available for it.
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Old May 05, 2011, 10:20 AM
Crash & Burn
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Glastonbury, CT
Joined Nov 2004
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What size spinner is on that? It looks huge. It looks like if you swap out a 2-bladed prop and the appropriate sized spinner, the overall performance should improve dramatically. I'm not surprised that it can't hover with a 3-bladed prop and one that has a 9" pitch. that's just too much pitch.
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Old May 05, 2011, 12:50 PM
Capt, USAF
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United States, NV, Las Vegas
Joined Feb 2009
922 Posts
Couldn't provide those exact numbers - Guess I'm not much of a numbers-guy when it comes to these RC planes...

To answer in broad generalities - It is heavier than other planes of this size that I've flown in the past, by a noticeable margin; most of the weight is concentrated in the nose. Quite obiviously built to absorb impact and rough landings - This is a very durable airplane, for sure.

The MX2 spinner is pretty large- An abnormal length that protrudes about 4" I would guess. I can't argue with the concept that a 2-blade prop would improve performance, but the 3-blade looks pretty cool - I painted my tips yellow and I really like the way it looks.
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Old May 06, 2011, 05:01 AM
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Joined Jul 2007
79 Posts
Hi,

I have just received my MX2 (European electronics version) :
Moteur : B3648 650kv outrunner
ESC+BEC : 45 A prise DEAN
Servos : 2x 9gr + 2 *17g high torque

Here are some measures which can be useful for those who are interested in this plane :
Motor weight
Motor & prop shaft weight
Motor & mount & prop shaft weight
Motor & mount & prop shaft & ESC weight

Which static power for this stock european motorization using Nanotech 4000mAh 4S 25-50C ?


About 663 W and 45 Amps with a battery completely charged and in good condition (about 8 cycles old)


Sorry, I have nothing to measure thrust.

Concerning manufacturing quality of this kit, I am disappointed given that now, at Hobbyking we can find planes very well finished and not expensive, but it is also necessary to take into account the size and the motorization supplied with this model, the deal remains thus correct.

Guys, what do you think about the assembly of this motor, it is not in the axis of the plane, is it normal (to counter motor torque) or it is necessary to take it in the axis ?





In order to upgrade the motorization set, I was looking to this motor :
Turnigy 4258 800kv
Kv (rpm/v) = 800
Weight (g) = 265
Max Current (A) = not specified
Power(W) = not specified
But according to customers comments, it is OK for 1000W+ under 4S batteries, giving about 3000gr of thrust. The problem with this motor is that there is nothing to fix the prop mount... there is a few hours work for the mod for fixing motor to the fuselage.
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Last edited by Spouny; May 06, 2011 at 01:00 PM.
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