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Old Jul 01, 2012, 10:59 PM
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United States, OH, North Canton
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Originally Posted by dazza44 View Post
for upgrade id go the brushless route,
more power makes it a lively plane,
ive gone park 450 route,and i fly it at night too
dazza44,

Does that Park 450 fit into the stock nose or did you have to mount it out front? I'm assuming you had to do a little bit of trimming if you fit it behind the mounting plate. Thanks again!

Stephen
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Old Jul 01, 2012, 11:03 PM
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Midvale, Utah, USA
Joined Mar 2005
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I like the motor mount you linked. Dont crash and you dont have to worry about damage (haha, riiiight.....)

MPX planes are tough, any anything that happens can be fixed.... Like I said I am partial to caster creations so that gets my vote. Dont know anything about the MPX power pack, other than it seems mfg's dont really worry about power consumption in their power packs. I have found their power packs take 2-3 times the amps that my brushless upgrades do, and Mine fly just fine. I use pretty much just towerpro motors so cant really help you on one that works with the stock mount... My only advice is to find something around 1200kv, use an 8x4 prop and a 3 cell battery around 2000mah.... I suggest that because its what I use....
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Old Jul 01, 2012, 11:11 PM
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Originally Posted by dacaur View Post
... Dont crash and you dont have to worry about damage (haha, riiiight.....)

...
Truer words may have never been spoken, haha! Thanks! I'll let you know what I end up doing.

Stephen
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Old Jul 02, 2012, 01:09 AM
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United States, CO, Manitou Springs
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Originally Posted by dacaur View Post
Definitely plug your rudder into the aileron channel.
Or do as I did, and just mix aileron to the rudder channel at 100%. Then when you add aileron servos, you don't have to move the rudder connection, just disable the mix.

I have to disagree somewhat on the ineffectiveness of the rudder in turning the plane. Even holding opposite aileron to counter the roll due to dihedral, the MiniMag cab turn very tight, flat circles on the rudder alone, though obviously there will be a lot of side-slip if you initiate such a turn at high speed. I've actually be doing a lot of this for fun, and to better learn aileron-rudder coordination.

And, not to be argumentative, but I also have to say that I think the motorcycle counter-steering analogy is not particularly useful here. The reason motorcycles turn when leaned (initiated by counter-steer) is because of the conical shape of the tire in cross-section generating camber thrust against the road surface. Neither counter-steering nor camber thrust are applicable to aircraft, where banking is initiated directly, and turning by banking is all about redirecting the lift vector.
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Old Jul 02, 2012, 03:29 AM
who put that tree there
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Quote:
Originally Posted by PREDATOR411 View Post
dazza44,

Does that Park 450 fit into the stock nose or did you have to mount it out front? I'm assuming you had to do a little bit of trimming if you fit it behind the mounting plate. Thanks again!

Stephen
fits inside no trimming at all,the only thing i did was change the front part of the mount.
i made one out of 5mm ply took ages sanding it too shape but its a good improvement..
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Old Jul 02, 2012, 06:14 AM
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Originally Posted by BrundleFlyBy View Post
Or do as I did, and just mix aileron to the rudder channel at 100%. Then when you add aileron servos, you don't have to move the rudder connection, just disable the mix.

...

And, not to be argumentative, but I also have to say that I think the motorcycle counter-steering analogy is not particularly useful here. The reason motorcycles turn when leaned (initiated by counter-steer) is because of the conical shape of the tire in cross-section generating camber thrust against the road surface. Neither counter-steering nor camber thrust are applicable to aircraft, where banking is initiated directly, and turning by banking is all about redirecting the lift vector.
That's definitely some food for thought. I think the biggest benefit of doing it that way would mainly be for taxiing with actual rudder stick. I think dacaur's point with that analogy may have been that the actual turning isn't caused by what most people think it is (or at least that's how I looked at it).

Stephen
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Old Jul 02, 2012, 10:28 AM
Never stop being a kid.
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Originally Posted by PREDATOR411 View Post
I think the biggest benefit of doing it that way would mainly be for taxiing with actual rudder stick.
Exactly. The big downside of learning on 3-channel with the rudder on the aileron channel is that you don't learn to "steer" on approach and on the ground using the rudder stick. Mixing aileron to rudder lets you learn that, and you can even "pretend" to fly coordinated, using both sticks (with the rates reduced, since the inputs are additive).

Quote:
I think dacaur's point with that analogy may have been that the actual turning isn't caused by what most people think it is.
Yes, I think you're right. But since motorcycling is one of my other main pursuits, I felt compelled to put my $.02 in.
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Old Jul 02, 2012, 06:06 PM
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Midvale, Utah, USA
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Originally Posted by BrundleFlyBy View Post
I have to disagree somewhat on the ineffectiveness of the rudder in turning the plane. Even holding opposite aileron to counter the roll due to dihedral, the MiniMag cab turn very tight, flat circles on the rudder alone, though obviously there will be a lot of side-slip if you initiate such a turn at high speed. I've actually be doing a lot of this for fun, and to better learn aileron-rudder coordination.
Try the same thing on a sport plane with a flat wing, then see how you feel about it. The minimags built in dihedral makes the rudder much more effective at turning the plane, even if you think you are keeping it perfectly flat with opposite aileron, the wing opposite the direction of the turn is still presenting its bottom to the airflow and helping the turn.

Quote:
Originally Posted by BrundleFlyBy View Post
And, not to be argumentative, but I also have to say that I think the motorcycle counter-steering analogy is not particularly useful here. The reason motorcycles turn when leaned (initiated by counter-steer) is because of the conical shape of the tire in cross-section generating camber thrust against the road surface. Neither counter-steering nor camber thrust are applicable to aircraft, where banking is initiated directly, and turning by banking is all about redirecting the lift vector.
Yea the comparison was more about things working very differently than people think they do. The first time I read about that in a motorcycle mag I didnt believe it, I had to actualy go out and try it for myself, and darned if it wasn't right. After that day I was a much better rider and found it much easier to avoid obstacles in the road, and Im sure it prevented a major crash at least once (microwave on a dark highway at night) since I wasn't depending on my brain to know how to do what I wanted.
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Old Jul 02, 2012, 08:44 PM
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Originally Posted by dacaur View Post
Try the same thing on a sport plane with a flat wing, then see how you feel about it. The minimags built in dihedral makes the rudder much more effective at turning the plane, even if you think you are keeping it perfectly flat with opposite aileron, the wing opposite the direction of the turn is still presenting its bottom to the airflow and helping the turn.
I could be wrong, but I think the area that the dihedral presents to the horizontal airflow at that point is relatively small compared to the area presented by the profile of the fuselage. Even without dihedral, I wager it would still turn reasonably quickly.

I'm not disagreeing that banking is extremely important to good turning performance; just pointing out that the idea that you can't turn a plane effectively on rudder alone is a little over-stated.

Maybe I should use a sailboarding analogy.

Cheers,
Dave
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Old Jul 02, 2012, 11:19 PM
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You are right that there is going to be more side area presented when you use only the rudder to turn without any dihedral. You are also right in that the plane will change heading.

However, with a normal size rudder vs the entire side of the fuselage trying to keep it going straight, that heading change is going to be very small, not enough to keep it within the confines of your average flying area.

With a big enough rudder and/or lots of throw you can get a much bigger direction change, but when you start trying to pivot a plane like that, it IS going to significantly increase drag and slow the plane (remember, the entire side of the fuselage vs just a small amount of the underside of a wing?), which will quickly start to lose altitude, keep it up and the inside wing will stall, but through all this, the plane will not have significantly changed direction, except its now going down rather than forward.

Of course, when it stalls, its going to drop the inside wing, which will probably turn it a bit in the direction you want to go.... assuming you have the altitude to recover, you might be able to pass if off as a "turn"....
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Old Jul 03, 2012, 08:00 AM
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Upgrades / Repairs

Well I ordered the motor mount from gobrushless.com yesterday and it should be here by Friday. Now for the brushless upgrade. I'd really prefer to go with an inrunner, but the only two options that I've been able to find are the E-Flite Six-Series Brushless 2000Kv (http://www.horizonhobby.com/products...28mm--EFLM2000) and the Himax recommended by Multiplex (http://www.horizonhobby.com/products...-mag-MPU993211). Both of these motors seem like overkill and it bugs me that the speed control that the MPX Power Pack comes with seems a little wimpy (would I even be able to run a 2S LiPo with that speed control and motor)?

Stephen
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Old Jul 03, 2012, 10:23 AM
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Another possible option that I just found would be a Great Planes Ammo 28-35-2200 In-Runner (http://www3.towerhobbies.com/cgi-bin...?&I=LXLWX9&P=0). Would any of these 3 motors (or any other available inrunners) be a good fit in the MiniMag? Thanks!

Stephen
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Old Jul 03, 2012, 10:53 AM
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United States, CO, Manitou Springs
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Originally Posted by dacaur View Post
However, with a normal size rudder vs the entire side of the fuselage trying to keep it going straight, that heading change is going to be very small, not enough to keep it within the confines of your average flying area.
Well, I should probalby just let this one go, but that just isn't right.

When a body in flight rotates, it does so around the center of gravity. Only the cross-sectional area behind the center of gravity will act to keep it on course (model rocketry 101). I'm sure, like most planes, the MiniMag is designed to have the center of pressure just slightly behind the center if gravity so that it will tend to be stable in yaw, and track straight. But the tendency is fairly weak, and easily overcome by the stock rudder. If it were too strong, the plane would be hyper-stable, and you'd get the weak response to rudder that you describe. You'd also have a plane that weather-vanes into every gust, making it difficult to maintain an off-wind heading

The bottom line is that the MiniMag turns on rudder much better than described, and it's not because of inadvertent banking due to un-countered dihedral or tip stalling, and it doesn't slow down or lose an excessive amount of altitude in the process - unless taken to the extreme, holding full rudder and near-full opposite aileron, essentially putting the plane in a broad flat spin.

I know this because I've done it - both ordinary turning at a normal flying radius, and the extreme, full-rudder, near-stall variety. And no amount of armchair aerodynamic analysis can trump that empirical truth. The MiniMag can, in fact, be turned effectively on rudder without banking.

That's my story, and I'm sticking to it.
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Old Jul 03, 2012, 07:36 PM
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Midvale, Utah, USA
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Originally Posted by PREDATOR411 View Post
Both of these motors seem like overkill and it bugs me that the speed control that the MPX Power Pack comes with seems a little wimpy (would I even be able to run a 2S LiPo with that speed control and motor)?
Stephen
RE: the MPX power pack, with the recommended battery and prop, yes the included ESC will work fine, but IMO, thats not really an efficient power system. and I doubt it would be much good at all on a 2 cell pack. If you want to go 2 cells, thats probably not the way to go. either of the other two you linked will work, but will require a smaller prop, which will give less thrust and more pitch speed, which, IMO, is not idea for a high drag cub type plane like this.

An outrunner swinging a bigger prop will be more efficient and would be my first choice. Do you already have 2 cell packs, or just plan to buy them? If you havent bought them yet, dont, a 3 cell setup is more efficient and you can use cheaper batteries, since you can get the same power to the prop using a bit less than 2/3 as many amps. A 3 cell 2000mah 8c pack is good for 16 amps, much MORE than enough to fly the minimag with great performance. Mine flies awesome on about 12 amps. Bt my mount isnt stock, if you want to use the stock mount (or the one you orderd) my recommendation would be a GWS 2212/13T outrunner (you can reverse the shaft to get it behind the motor mount), 3 cell 2000mah pack and a 7x4-8x6 prop.... The motor is less than half the cost of the ones you are looking at, and will give you as good or better performance, using less amps. (8x6 should be around 10 amps on 3 cells)

I always look for way to use the least amount of power possible with good performance. That setup wont give you unlimited vertical, but it will be much better than stock, with long flight times and no hot batteries.... The multiplex power pack with its 5.5" prop draws 15 amps. It will give you a higher top speed, but less acceleration than what I recommended. (acceleration = gets you out of trouble when you stall)


Quote:
Originally Posted by BrundleFlyBy View Post
I know this because I've done it - both ordinary turning at a normal flying radius, and the extreme, full-rudder, near-stall variety. And no amount of armchair aerodynamic analysis can trump that empirical truth. The MiniMag can, in fact, be turned effectively on rudder without banking.

That's my story, and I'm sticking to it.
Well, Like I said, even in my first post, the minimag isnt a good example of how ineffective a rudder can be, due to its built in dihedral. I did state that with a FLAT WING, which the minimag does NOT have the rudder is not effective at turning a plane.

If you have experience flying a flat wing plane that turns just fine with rudder alone, thats one thing, otherwise, perhaps accusing others of "armchair aerodynamic analysis" isnt really the way to go.
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Old Jul 04, 2012, 12:29 AM
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Thank you so much for the recommendation, dacaur! Maybe I'm just being a little particular here, but I really would prefer an inrunner, even if it costs more (I'd still like to keep things reasonable, of course). I did a little bit of searching through this thread, since I'm still horribly behind (made it to page 136!) and I found someone running a slightly different version of the Himax motor at a lower kv. The 2815-1400 can be purchased here (http://www.maxxprod.com/mpi/mpi-264.html) as a part of Combo 2815A. I know it's not cheap, but I think that it's probably the best performing inrunner that I'll be able to find for the MiniMag. I don't have a problem running a 3S pack, but I was just trying to keep some stress off of the BEC for future operation with 4 servos. The main thing that I was worried about when running a 2S pack is doesn't doing that bump up the current the speed control will have to deal with? If that's the case, would the Thunderbird 18 still be up to the task? Sorry if this is a silly rookie question / mistake .

Stephen
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