RE: video: 20 ft wingspan B-24 crash on maiden flight....  
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RE: video: 20 ft wingspan B-24 crash on maiden flight.... - 10/10/2004 1:07:08 AM   
bigbubba



Posts: 141
Joined: 9/4/2004
From: Grantham, UNITED KINGDOM
Status: offline 		I think I undertsand!

Thanks

Sheridan

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(in reply to teryn1)
       Post #: 126

RE: video: 20 ft wingspan B-24 crash on maiden flight.... - 10/10/2004 3:30:16 AM   
teryn1


 

Posts: 273
Joined: 12/31/2001
From: Green Valley, AZ, USA
Status: offline 		Dave:

quote:

That would make the aircraft roll away from the turn which is opposite to the effect being discussed!


Not sure what you mean by this. Because of coupling effects, if only the rudder is suddenly deflected to the left in normal straight and level flight, the airplane will yaw and slowly roll the left. This has nothing to do with adverse yaw (because we're not moving the ailerons). This is not a efficent way of turning the airplane because it results in a large yaw, generating drag, prior to the roll action (due to inertial effects). Plus, the coupling effect is small (airplane designed well), then you may not roll at all! Fundamentally, the rudder is not making the larges changes in the airplane heading (direction); the tilting of the lift vector due to angle of the wings is responsible for turning the airplane.
Adverse yaw is created by the ailerons. Adverse yaw causes the airplane to yaw in the opposite direction to the roll because of aileron deflection. This happens with no input to the rudder.

More info on coupling effects in: Design for Air Combat by Ray Whitford


Side point: Some airplanes are capable of "flat turns", turning with no bank angle. this due to the fact that rudder input results in a angle-of-attack of the FUSELAGE relative to the air and it generates lift (sideways) driving the airplane around in a circle.

quote:

I thought the roll was induced because a yaw, created by the rudder, say, to the left makes the right wing go faster and therefore creates more lift on the right thus the roll to the left


this could be another coupling effect, but not the only one.

quote:

This also explains why there is a yaw 'away' from a turn, when using ailerons because greater lift = greater drag which tends to yaw the plane out of the turn.


this is correct. Called adverse yaw. The purpose of the rudder is correct this problem. But not required for safe flight.

< Message edited by teryn1-RCU -- 10/11/2004 5:15:36 AM >

(in reply to David Cutler)
       Post #: 127

RE: video: 20 ft wingspan B-24 crash on maiden flight.... - 10/11/2004 4:21:40 PM   
dag21463


 

Posts: 21
Joined: 6/10/2004
From: fishers, IN,
Status: offline 		Quote:
In a banked turn, the gravitational force is not perpendicular to the "wing span" as you say. I challenge you to show me something in the physics that says a rudder turns the airplane and then I will believe you. I can tell that you don't have a clue what you are talking about. Some of the things you have said are wrong, and some are the same as what I have said already. Your Champ and your Cub will turn just fine without rudder...I guarantee it.

As an owner in a J-3 cub( part owner) you have no idea what you are talking about. You have to use rudder to make turns even look even safe. But like you say( you can turn 99% of the planes out there with out using rudder), ok I guess you could go as far to say you can fly safely with out a elevator if all you wanted to do was fly level. I guess you could say you could fly a plane with out wheels. But flying starts from the moment you start your aircraft. I once saw a plane ground loop right in to a small child. Guess rudder would not have helped. One of my best friends flys old war birds and says that most of the bombers could not be flown safe with out rudder as the tail would fall thru the turn pushing the nose up. And there are alot of old bi-planes that wont really turn with out rudder. If all you want to do is yank and bank thats one thing. You can not hold a vertical line with out rudder. Also I saw a young guy one time trying to nurse a 1/4 scale p-51 in dead stick and he got it slow we told him to use small rudder inputs to get back to the runway. The plane stalled and fell into a parked car. Everyone says when your slow try using small inputs of rudder. One last thing there are a ton of park flyiers out there that fly on only elevator and rudder. And guess what I have been able to roll one with rudder only and it turns great. WOW. Rudder would have help this plane. B-24. Now would it have saved it, we will never know. My 14' b-29 wing flex's as much as this plane and it flyies great. Real b-52 wings would flex as much as 15 feet or more. They were made to do that.

(in reply to William Robison)
       Post #: 128

RE: video: 20 ft wingspan B-24 crash on maiden flight.... - 10/11/2004 8:46:33 PM   
beenie



Posts: 379
Joined: 10/16/2002
From: Baton Rouge , LA, USA
Status: offline 		Dag21463-
I'm glad that you too have noticed that Cubs don't turn well without rudder. The 7AC that I learned to fly tailwheel in would turn the opposite direction that you pointed the stick! Rudder was essential in all flight regimes.

I do not appreciate being accused of not knowing what I am talking about by someone who suggests that rudder makes a plane bank because "the fact that rudder (vertical tail) is physically located above the airplane CG, rudder input causes a rolling moment about the centerline of the airplane, causing the airplane to roll".

What about airplanes with the majority of the rudder area below the longitudinal axis?

My apoligies to the readers of this thread for dragging it way past the original topic. The thread previous to this one is by someone who claims to fly aircraft similar to the one in question. He says that rudder would have helped the cause.

< Message edited by beenie -- 10/11/2004 8:47:14 PM >

(in reply to dag21463)
       Post #: 129

RE: video: 20 ft wingspan B-24 crash on maiden flight.... - 10/11/2004 10:13:51 PM   
dag21463


 

Posts: 21
Joined: 6/10/2004
From: fishers, IN,
Status: offline 		Thanks, beenie.

The reason I am so hard headed about this is that their is alot of people that look at these forums for help and a learning. (Real) pilots look at the entire flight as flying an aircraft. I have seen at alot of EAA fly-in's were ww1 aircraft have flown in and the pilots say they couldnt even fly straight and level with out a rudder. And they say they could never turn with out having the plane turn left when they want to go right. Maybe its just that with alot of flying the rudder just becomes a part of flight. I have flow alot of differnt types of aircraft and I guess if you count only stright and level flight as flying then you might not need a rudder.

There is a guy in Dayton Ohio with a 99" B-24 electric that has his rudder mixed in to his rolll so that he can get his plane to turn correctly. I saw this plane fly and when he put left roll in to it the nose would turn hard right then the plane would start a real sloppy turn. The plane looks like it is skidding in the turn and the nose starts climbing with out a bunch of rudder.

I also do not appreciate being accused of not knowing what I am talking about considering the thousands of hours and 3 degrees in this subject. And if you look at most fluid dynamic models that are used in sims, rudder has alot to do with turns when it comes to physics. I even sent a professors from 20 years ago a link to this forum and he is laughing his butt off about the whole rudder argument. He even said that rudder would has possiably saved the B-24. And he even teaches how rudder works in the physics sence in his master studies.

I just hope every one reading this forum understands that there is a big differance between yank and banking (which can be fun) and really flying a scale war bird. And my 50% Pitts S-1 needs rudder to make the turn not look sloppy. And it needs a TON of rudder on Full power take offs. 16.5 hp turns a 30" prop. WOW.

(in reply to beenie)
       Post #: 130

RE: video: 20 ft wingspan B-24 crash on maiden flight.... - 10/12/2004 2:02:35 AM   
dag21463


 

Posts: 21
Joined: 6/10/2004
From: fishers, IN,
Status: offline 		teryn-1

Here is your physics answer to how a rudder turns an aircraft.

¥¥¥MOMENT TOTALS, AIRCRAFT AXIS SYSTEM, BEFORE ASSYMETRIC FUEL/ENGINE MASS EFFECTS¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥
¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥
L= -0.29 N-m, pos right.
M= 0.09 N-m, pos up.
N= 0.03 N-m, pos right.
¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥

¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥
¥¥¥MOMENT TOTALS, AIRCRAFT AXIS SYSTEM, AFTER ASSYMETRIC FUEL/ENGINE MASS EFFECTS¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥
¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥
L= -0.28 N-m, pos right.
M= -0.27 N-m, pos up.
N= 0.04 N-m, pos right.
¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥


¥¥¥FINAL TOTAL FORCES, ALONG GLOBAL AXIS¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥
f_east = -9.33 N.
f_up = 211.69 N.
f_south= 10.08 N.

¥¥¥FINAL TOTAL TOTAL MOMENTS, ABOUT AIRCRAFT AXIS (pos right/up/right)¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥
L (roll) = -0.28 N-m.
M (pitch)= -0.27 N-m.
N (yaw) = 0.04 N-m.

¥¥¥MASSES TO GET FROM FORCES TO ACCELERATIONS¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥
mass = 21.75 kg (ice accretion will change mass and MI if present! ice accretion mass ratio is 0.00 now)
roll MI= 4.15 kg-m-m... M/mi=accel in RADIANS per sec.
pitch MI= 9.78 kg-m-m... M/mi=accel in RADIANS per sec.
yaw MI= 12.88 kg-m-m... M/mi=accel in RADIANS per sec.

¥¥¥FINAL TOTAL LINEAR ACCELS, ALONG GLOBAL AXIS (pos north/east/up)¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥
a_x= -0.43 m/ss.
a_y= -0.06 m/ss.
a_z= 0.46 m/ss.

¥¥¥FINAL TOTAL ANGULAR ACCELS, ABOUT AIRCRAFT AXIS (pos right/up/right)¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥
Pdot (roll) = -2.50 deg/ss.
Qdot (pitch)= -0.60 deg/ss.
Rdot (yaw) = 3.16 deg/ss.
This is the plane turning very nice with rudder only
And if you look it is close to a level turn once it has started

¥¥¥FINAL TOTAL LINEAR VELOCITIES, ALONG GLOBAL AXIS (pos north/east/up)¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥¥
v_x= 35.21 m/s.
v_y= 21.91 m/s.
v_z= 2.03 m/s.

This is the output from a sim on my s-1 pitts. The plane turns better with less chance of any stall.
And yes rudder does directly turn a plane.
Hope this helps you.

And if you are a real pilot or better yet an RC pilot. You could never do turns around a point with out rudder. It is one of the first thing you learn in flying.

And hopefully you are not to hard headed to see proof that you are wrong.

Good luck and happy flying.

(in reply to dag21463)
       Post #: 131

RE: video: 20 ft wingspan B-24 crash on maiden flight.... - 10/12/2004 2:45:24 AM   
teryn1


 

Posts: 273
Joined: 12/31/2001
From: Green Valley, AZ, USA
Status: offline 		dag21463 and others, you guys are so smart! you proved me wrong with the sim and your subjective observations of real airplanes flying! Rudders are necessary to turn airplanes! Everything I said is wrong; I should have known to check a "fluid dynamics model" for the answer in the first place.That model is awesome, Where can I get one of those? I feel so stupid. The only thing that turns the airplanes is rudders, remember that...Just believe whatever you see at first glance (or look at the sim) and you'll be on the road to success. Let me know what else you want to hear about airplanes and I will say it! That's the least I could give to you guys for being so stupid and spreading this misinformation! If I have any other questions, I'll be sure to ask you guys....I am so glad that there are experts like you on RCU to help us with our problems. what a learning experience!

< Message edited by teryn1-RCU -- 10/12/2004 3:37:00 AM >

(in reply to dag21463)
       Post #: 132

RE: video: 20 ft wingspan B-24 crash on maiden flight.... - 10/12/2004 5:07:28 AM   
dag21463


 

Posts: 21
Joined: 6/10/2004
From: fishers, IN,
Status: offline 		You are quite welcome,

But this is all about a B-24 crash, remember?????

But keep in mind you are the one that started saying people were wrong and didnt know what they were talking about.

And there are allot of aviation degreed people on here with CFI, CFII, IFR, commerical ratings and degrees with aviation design - avaition science degrees.

And we all e-mail each other about subjects just like this one. When we are not at our real avaition/engineering jobs.
We are all here to help.

Any RC pilot learning to fly should learn what the left stick is for, and its no just the go fast stick either.

And Nasa, boeing, spaceship one, airbus, and other big names have used "blade element theory" and "fluid dynamics modeling" in test flying aircraft. Real aircraft are built from this every day. And it has been used for the modeling world for about 5 years.

All of the aircraft I have built in the past 4 years has been flight tested using these sim's. It tell me the correct CG, wing load, power factor and about 25 other forces on the aircraft.
You can create any air craft in it in any size and it will output what it takes to make it fly right.

But this all started about trying to help people learn from a bad crash and a loss of a great plane that someone put hundreds of hours into.
And all of us (guys) with avaition back grounds only hopes that next time the pilot of a scale war bird bomber will remember to use his left thumb(rudder) and may save a aircraft he loved.

Take care and Happy flying.

(in reply to teryn1)
       Post #: 133

RE: video: 20 ft wingspan B-24 crash on maiden flight.... - 10/12/2004 6:46:03 PM   
teryn1


 

Posts: 273
Joined: 12/31/2001
From: Green Valley, AZ, USA
Status: offline 		Yep, as I thought, right over your head...

(in reply to dag21463)
       Post #: 134

RE: video: 20 ft wingspan B-24 crash on maiden flight.... - 10/12/2004 7:19:53 PM   
MikeMc



Posts: 572
Joined: 2/19/2004
From: Union City, CA, USA
Status: offline 		So many absolute answers. I should have been a philosopher instead of an engineer.

I think we need to borrow NASA's wind tunnel on this one. Aerodynamics is so screwed up I find it funny how no matter how smart people are we have to revert to trial-and-error in wind tunnels for the final decision.

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(in reply to teryn1)
       Post #: 135

RE: video: 20 ft wingspan B-24 crash on maiden flight.... - 10/12/2004 7:24:48 PM   
CGRetired



Posts: 4223
Joined: 9/14/2004
From: Galloway, NJ, USA
Status: online 		Remind me never to ask any of you guys a question. I would hate to be accused of being stupid.

(in reply to teryn1)
       Post #: 136

RE: video: 20 ft wingspan B-24 crash on maiden flight.... - 10/12/2004 7:37:50 PM   
MikeMc



Posts: 572
Joined: 2/19/2004
From: Union City, CA, USA
Status: offline 		Stupid? Don't worry. We hate everybody equally.

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(in reply to CGRetired)
       Post #: 137

RE: video: 20 ft wingspan B-24 crash on maiden flight.... - 10/12/2004 7:52:09 PM   
CGRetired



Posts: 4223
Joined: 9/14/2004
From: Galloway, NJ, USA
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(in reply to MikeMc)
       Post #: 138

RE: video: 20 ft wingspan B-24 crash on maiden flight.... - 10/12/2004 8:45:51 PM   
dag21463


 

Posts: 21
Joined: 6/10/2004
From: fishers, IN,
Status: offline 		teryn-1


What is funny is it is over only your head. At least thats what all of us pilots/engineers (21 of us that are in this forum) think. At least in understanding a rudder. We cant believe how long you stuck with this losing battle.

Thanks for the entertainment

And you asked if anyone could show you the physics behind a rudder turning a plane you would like to see it. And we showed you.

And dont get me wrong but you write like all you do is fly 3D and have never thought about flying a scale plane. I have no idea what you really fly, but you write like all you can do is hover. Dont get me wrong I love 3D and think it has a great place in our hobby.

A flight start at a nice controlled and safe take off. (You dont have 10 guys standing in front of the plane with the prop turning 10,000 rpm)Then you have fun flying around doing what ever turns you on, then a nice safe approach and then a great 3 point landing. (To do that I think you need a rudder)

And dont take it personal teryn-1 you are the one that got all of us started about turning planes safely with out the us of rudder or rudders.

But all of us (pilots/engineers) are done with this and we wont pick on you any more.


Happy Flying

(in reply to CGRetired)