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Old Jul 05, 2012, 03:16 PM
Memento Mori
Diesel6401's Avatar
United States, NC, Charlotte
Joined Sep 2009
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I was wishing for a tad more speed also, but with how lightweight the plane is and how thin the wings are, how much faster could you really go w/o say wings folding in a high G turn. I think it looks really scale for its size. All this

Anyone using TPs in this? What size fit with no modding (hate to cut into a clean un-crashed plane).

Sbach talk makes me want to go get one now lol.
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Old Jul 05, 2012, 03:20 PM
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United States, CA, San Diego
Joined Jun 2007
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Quote:
Originally Posted by grovey View Post
Also, can you explain what a dutch roll is?
Dutch roll is a phenomenom experienced by many swept wing planes, and it's a result of the swept wings.

Look at the plane from the front, head on. Now induce a yaw. (Twist it some left or right.) Now really look at the wings. You just made the wing that came forward have a longer wingspan than the one that went back, as well as the fuselage now blocking some airsteam from the inboard part of the wing that went back. This causes several things, among them it increases the lift and drag on the 'longer' wing. So that wing will rise and at the same time, the increased drag will yaw the plane back the other way. The momentum can make that yaw go back the other way so now the other wing has greater lift & drag. In some designs, this can cause an increasing oscilation that won't settle itself without some control input. Most (Full scale!)swept wing planes therefore have a yaw damper that automatically keeps the plane straight in the yaw axis. In fact the FAA requires yaw dampening unless the plane has been proven to self stabilize after a dutch roll is purposely induced. The 737 is one that doesn't require it. I guess our models are designed well! I haven't seen anything like a dutch roll in my MiG.

I'll try to find an awesome and scary video of a dutch roll. BRB!
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Old Jul 05, 2012, 03:21 PM
Just wanna fly!
grovey's Avatar
United States, TX
Joined Apr 2008
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Quote:
Originally Posted by xmech2k View Post
Dutch roll is a phenomenom experienced by many swept wing planes, and it's a result of the swept wings.

Look at the plane from the front, head on. Now induce a yaw. (Twist it some left or right.) Now really look at the wings. You just made the wing that came forward have a longer wingspan than the one that went back, as well as the fuselage now blocking some airsteam from the inboard part of the wing that went back. This causes several things, among them it increases the lift and drag on the 'longer' wing. So that wing will rise and at the same time, the increased drag will yaw the plane back the other way. The momentum can make that yaw go back the other way so now the other wing has greater lift & drag. In some designs, this can cause an increasing oscilation that won't settle itself without some control input. Most (Full scale!)swept wing planes therefore have a yaw damper that automatically keeps the plane straight in the yaw axis. In fact the FAA requires yaw dampening unless the plane has been proven to self stabilize after a dutch roll is purposely induced. The 737 is one that doesn't require it. I guess our models are designed well! I haven't seen anything like a dutch roll in my MiG.

I'll try to find an awesome and scary video of a dutch roll. BRB!
Thanks for the explanation, I wonder if that is what made me crash! It sure sounds like it, it really took me aback.

It started with changing my rudder position (yaw)
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Old Jul 05, 2012, 03:25 PM
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United States, CA, San Diego
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Here it is:

Tu-154 Out of Control (0 min 36 sec)


I'm amazed he landed that thing. I'm sure they had to find new seat cushions at least!
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Old Jul 05, 2012, 03:27 PM
Just wanna fly!
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United States, TX
Joined Apr 2008
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See, I was coming out of a turn where I was using right rudder, I then changed from right rudder to left rudder, and wammo

What you have explained and what I see in that video could have been what sent my plane out of control.
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Old Jul 05, 2012, 03:30 PM
Memento Mori
Diesel6401's Avatar
United States, NC, Charlotte
Joined Sep 2009
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Quote:
Originally Posted by xmech2k View Post
The 737 is one that doesn't require it.
737s had a really bad un-controlled rudder hardover issue that resulted in several crashes. Still the most successful commerical plane ever built! Never had the joy of working on one. Did work Airbus's for a little while though.
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Old Jul 05, 2012, 03:33 PM
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Originally Posted by Diesel6401 View Post
737s had a really bad un-controlled rudder hardover issue that resulted in several crashes. Still the most successful commerical plane ever built! Never had the joy of working on one. Did work Airbus's for a little while though.
Yes, but that had nothing to do with dutch roll. It had to do with the actuators. I never got to work on them, either. Commuters, 727, 747, DC-10's for me.
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Old Jul 05, 2012, 03:35 PM
Just wanna fly!
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United States, TX
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Quote:
Originally Posted by grovey View Post
See, I was coming out of a turn where I was using right rudder, I then changed from right rudder to left rudder, and wammo

What you have explained and what I see in that video could have been what sent my plane out of control.
@xmech2k

Does my explanation fall into the cause of a dutch roll, certainly seems that way to me. If I remember correctly, what through me, was the plane seemed to have flipped over after my rudder input.
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Old Jul 05, 2012, 03:39 PM
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United States, MI, Grand Traverse
Joined Oct 2008
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Quote:
Originally Posted by Diesel6401 View Post
Prop vs edf doesn't matter that much in planes this size. I have 800mm T28 that will keep up with and pass most artr edf's in its size. Its a head turner for sure. My point is under in a certain speed range (let's say (sub 100mph), prop vs edf really doesn't matter in speed. Instant punch/acceleration always goes to prop even in real aircraft.

Mine needed a good bit of clicks of trimming. I just checked it and the ailerons weren't as level as I thought they were. I just adjust them and hope to try tonight. I needed 3 or 4 clicks of left ail trim to get her to fly straight.
I just noticed a build problem with my mig that could be causing the problem. The two rudders are not aligned the same. When the lower half is aligned with the tail the upper is 1-2mm right! as the speed changes the AoA changes making the upper and lower portions of the rudder more or less effective and the coupled roll would then change the speed more completing the cycle. Now it is time to take apart a brand new plane and fix a build problem.

Also found servo wires in the flow behind the fan Not just the motor wires, servo wires....

Quote:
Originally Posted by xmech2k View Post
Here it is:
http://youtu.be/0uWFL24vLPA
I'm amazed he landed that thing. I'm sure they had to find new seat cushions at least!
WOW!!! That was a perfect full scale example of a very nasty dutch roll

I like this animated gif: Really makes the motions easy to understand.

Quote:
Originally Posted by grovey View Post
Does my explanation fall into the cause of a dutch roll, certainly seems that way to me. If I remember correctly, what through me, was the plane seemed to have flipped over after my rudder input.
Did you have a pitch up before the roll? Could be the "sabre dance"

when the plane slows the outboard portions of the wing stall first because of spanwise flow. This causes the center of lift to move forward. This causes the plane to pitch up which them amplifies the process and causes even more of the wing to stall. Basically the plane goes from flying to completely stalled quickly. If you were flying slowly when you gave it rudder this could happen and the abrupt stall and rudder would cause it to flip over very quickly (think snap-roll)
-Brian
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Old Jul 05, 2012, 03:43 PM
BMFA 190658
SilentPilot's Avatar
United Kingdom, Yeadon
Joined Mar 2007
4,327 Posts
A dutch roll!

That is what my party trick is with my UM Stryker, just been calling it a rudder roll till now!!!
A friend at my Club said 'Yours rolls all wrong' I did a propper Aileron Roll and he wanders off saying Its ok now. Think he missed the point
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Old Jul 05, 2012, 03:49 PM
Just wanna fly!
grovey's Avatar
United States, TX
Joined Apr 2008
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@kalmon

I am trying to recall. It really happened fast. I think it did pitch up and I think I was coming in to land. So I guess I may have dropped speed.
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Old Jul 05, 2012, 04:02 PM
Volts times Amps = Wot?
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United Kingdom, Scotland, Edinburgh
Joined Mar 2003
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Quote:
Originally Posted by lesodell View Post
jeezeypeeps
what did they say they are going to do about the ones that are already out there ? are all the 300 that way
I get the impression the numbers are small. They are contacting anyone who has purchased from the faulty batch (I got an e-mail myself - 40 minutes too late unfortunately )
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Old Jul 05, 2012, 04:11 PM
3D... the only way to fly!
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Kissimmee
Joined Apr 2010
336 Posts
I ordered yesterday, and received an Email today from Richard!
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Old Jul 05, 2012, 04:35 PM
Memento Mori
Diesel6401's Avatar
United States, NC, Charlotte
Joined Sep 2009
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Quote:
Originally Posted by xmech2k View Post
Yes, but that had nothing to do with dutch roll. It had to do with the actuators. I never got to work on them, either. Commuters, 727, 747, DC-10's for me.
O yea I know about nothing dealing with dutch roll, just was making conversation

Nice... A&P like me?

CRJ200s (hate with a passion!)
Emb170 & 175s (my favorite!)
Emb 145
A319s
DoJet328-300s..
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Old Jul 05, 2012, 04:38 PM
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United Kingdom
Joined May 2012
212 Posts
I just maidened my mig. wow this plane is amazing! Flew 7 packs through her.
As others have said i needed alot of down elevator to maintain inverted flight, almost caught me out the first time i tried it!
Now this may go against opinion but i flew it back to back with the sbach and i think the mig is a little quicker top end! You have to wind her up though!
I was flying nice long turns and coming in low and fast, great fun!!!
i've got some miniaviation 300s, worked perfect. no polarity issues.
Needed 4 clicks of aileron and a little up elevator.
Ground take off's were easy, landings are fast and loooong!! ended up taking of the landing gear and belly landing in the grass.Don't think i'll be putting it back on for a while either, it lands soo nice without it. 7 flights with not a mark on her.
Overall this is a great plane and the sound is something no other umx plane can match!!
love it!!
Out of interest regarding the miniaviations with the wrong polarity.How did you manage to charge them if the plug is wired wrong?
cheers simon
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