Hi....I'm new to the RC airplane hobby and I'm doing alot of reading and flying. I'm catching on fairly well to the phrases, lingo and terminology but I can't figure out what is meant by "3D", other than the obvious, but I thought the idea behind all airplanes was to fly in 3 dimensions. Could someone define it for me please.

Thanks

3D flight is a condition in which you are flying the plane in a stalled condition. (fact)

Most other definitions are a subset of this one, but this definition is the most accurate. (IMHO)

Do you mean hovering ("hanging on the prop") or something else. I don't really understand your answer because I thought planes fall down when stalled.

Thanks again

When the plane is stalled, it will fall down unless lift is coming from some other source. The Propeller When the propeller thrust is generating the balance of the lift then you will have 3D flight. When hanging on the propeller, the lift is generated by the propeller. Direction control is achieved by the prop wash flowing over the control surfaces. Deflecting the prop wash over the control surfaces while maintaining enough thrust to stay in the air will allow you to do many maneuvers in the "stalled" condition.

Thank you. Now I understand.

For 3 D plaens ur Diameter ofthe prop is greater , thus giving the engine more thrust , less speed .

This enables the plane to hang by the prop. as they say .

im still confused if some one can explain again that would be good

if prop not turning and no forward movement you are stalled fall out of sky , if you have foward movement then air over wings therefofe lift .. if you are flying into a 20 knot wind and maintain power to equal 20 knot you can stay in position hover

so is 3d same as gliding ( yep still confused) ??

Prop is turning. Prop blast over the surfaces it what keeps the plane in the air. The wing is stalled at this point.

OK Rusty, Let me try this again.
We need to look at airspeed and the air's effect on the airframe. Ground speed is meaningless.

If the propeller is not turning and their is no forward movement, the plane will fall. As it falls you will gain forward movement and with enough airspeed can glide. Glide angle will depend on the wing loading of the plane.

If you are flying at 20 knots, you have a wind speed of 20 knots and your plane has a stall speed of less than 20 knots, you will be flying. If your plane has a stall speed of greater than 20 knots, your plane will be stalled.

A gliding plane is not stalled since you have sufficient airflow over the wing to generate lift. If their is not sufficient airspeed to generate lift, then you are stalled.

I hope this helps.

Guys, Rusty is referring to the engine when he says "stalled." Hence his talk about the prop not turning and question about gliding.

Rusty, when an engine on an RC plane quits you'll usually hear it referred to as "dead stick." That comes from the throttle stick no longer doing anything. In aviation, when someone speaks of a stall they're almost always talking about a lack of proper airflow over the wing which results in insufficient lift.

3D is a flying style that is done in this "stalled" condition, where the wing isn't producing lift to keep the airplane in the air. In this case it's the thrust of the engine that provides the lift and airflow over the control surfaces.

Does that help clear things up?

Well, I've pretty well got it, thanks to all of your responses. Now if someone would just tell me what "3D" stands for or why they call it "3D", that will pretty much finish this thread for me. Thanks for all of your help.

It means 3 dimensional. Since flying is done in 3 dimensions it probably wasn't the best choice however it stuck. A new title that is being used is "artistic aerobatics" and a group that flies sequences made up at least partially of "3D" maneuvers is called
"EFE" which stands for extreme flight envelope.

EXCAP232

I thought 3D meant "Don't Dare Disturb", I'm tying up the runway for the next 20 minutes....<G>

While the AA term is new to me, EFE, I have heard.
It is also referenced as XFE. I actually prefer either term over 3D.

3D flying means that ya got a HUGE motor on a LIGHT plane and you can wring it out and run the snot outta the plane.

Planes doing 3D flying are doing stuff that planes don't normally do. Like hanging on the prop. 3d flyers make the planes flop around in the air. To see a good 3D pilot perform is amazing to me. Those guys can make planes do stuff that I would have thought was impossible.

You're not stalled! Stall occurs during boundary layer separation when the wing exceeds the critical angle of attack (Amax). When you have no airspeed, you cannot exceed Amax. Your prop is your wing (Rotor in a copter) during a 3D maneuver.
Fred

Gotcha !! it would seem that the term 3D FLYING is probably not the best description .. as for flying in unusal patterns .. not a problem i do that all the time, i did not realize i was flying 3d i thought i was setting up for another crash and burn

thanks for the posts

I have a file of Kirby Chambliss at Oshkosh doing EFE in a full size plane. He is awesome. I got this from a friend. I will be glad to give the author credit!

Alright....there have been a lot of complex definitions on here, and I agree with most all of them. But the easiest way of explaining this is just how MikeL put it when he said "it's the thrust of the engine that provides the lift and airflow over the control surfaces. "

Basically, 3d takes an engine with a lot of power so that the engine is what is holding the plane up....not the wing. That is what all of these guys are saying basically.

Welcome to the hobby!

torque_roll

the proper and technical definition is the following:

The normal motion of airplanes occurs in the 2D plane, or a imaginary plane that parallels the wings and extends to infinity. There is no "depth" to this 2D plane. All motion in normal 2-dimensional flight is restricted to that infinite plane. In other words, there is motion in 2 axis of the aircraft. Rolls and loops constitute (among many others) 2d flight.

3D flight is when the motion of the aircraft extends to all 3 axis, such as in hovering of a lomcevak manuever. Or any motion where the aircraft is operating outside the 2-D plane.

So, this isn't just a magic or imaginary coined term as you guys suggested, but there is a real technical definition behind it...

-Teryn

3-D means "I wish I had a Helicopter".

There have been repeated statements that stalled wings don't generate lift. This really isn't correct. Stalled wings can and do generate lift. RedXfred is basically correct, at Zero airspeed the wing is useless. You must fly entirely on the prop for "3D" maneuvers such as hovers and torque rolls. However, for "3D" maneuvers that have airspeed, be it forward movement or prop blast, the wing generates lift. So, for elevators and harriers, the wing is partly responsible for the lift (prop does the rest.)

Like RedXfred said, stalls occur when the boundary layer separates from the wing. This is the beginners section and I don't want to get into a super technical discussion. So in basic terms, as you increase the angle of attack on a wing, it makes more lift, up to a point. If you keep increasing the angle of attack, you will reach a point where the lift actually starts to lessen. This point is basically when the boundary layer seperates and we call this condition a stall. For most airfoils this happens around 10 to 15 degrees of attack. The lift doesn't all of a sudden vanish, it just gets smaller. Once stalled, as you increase the angle of attack your lift continues to get smaller until it is zero, which typically occurs when the wing is at 90 degrees angle of attack.

Additionally, higher angles of of attack (especially stalled wings) have a lot of drag. I think the reason many think stalled planes don't generate lift is because not only do they lose some lift but the plane slows rapidly, making matters worse. It may look as if you lost all your lift and you dropped like a rock, but you didn't. The lift may be too small to hold your plane at the same altitude so your plane falls, but some lift is still there.

In "3D", many maneuvers take advantage of stalled lift. The missing lift required to maintain altitude is provided by the prop. I haven't done wing tunnel tests, but I can see where it could be possible that the root area of the wing is not stalled in a harrier because of prop blast, but I gotta believe that the wingtips are stalled (hence wing rock in harriers) as they are not in the prop blast. I typically will do a harrier at about 30 degrees AOA or higher, tips almost gotta be stalled.

I've never heard the phrase EFE but the name does seem to describe better what for the most part we all (or at least I) call 3D flight. I kinda prefer EFE (how would you pronounce that? ee-fee?) to 3D... I'll have to start using it.

Hey Minn, isn't it funny that all heli guys are trying to fly helis like planes (KE, point rolls, etc.) and the plane guys (like me) are trying to fly planes like helis?

MinnFlyer as usual you provide the proper levity to the question!

I have a helicopter and its much more fun to 3D an airplane.......