3d electric airplane video
 

A video I took of my friend flying his 3d electric airplane. This was about his 5th flight or so on this particular plane.

http://www.youtube.com/watch?v=ag7oSDo3MR8

That's amazing. I only ever made one model aeroplane and didn't even get to fly it. Sold it on. Anyway, forgive me but how on earth is a plane able to do all that? It seems to defy the laws of gravity. I'm guessing the motor is just really powerful and the rest of it so light? Plus of course you've got a skillful pilot.

Could he end the flight by catching it in his hand? That would have been the ultimate finish.

My understanding is that, when a model is called a "3D" model it means the propeller's thrust at full throttle is greater than the weight of the aircraft.

Many kinds of flight stabilization equipment is now available for model planes such as this. A rate gyro can be wired into the aileron's, rudder's, or elevator's, (or various combinations) servo circuit to allow for more stable flight control and precise aerobatics.

Almost like putting the BSA from a PT inside...

Compliments to the videographer -- great camera work. Encourage the pilot to keep practicing and he'll eventually learn how to keep the plane nice and level.:rolleyes:

Thanks for sharing.

Yes, we actually do this quite a bit.


You're right. A very good power to weight ratio really helps 3d flying


Typically, only helicopters have gyro's onboard. I've never seen an airplane using gyros. You do everything yourself when trying to hover an airplane. You've still got the standard 4 controls. (aileron, elevator, rudder, and throttle) But changing one required compensating with another. Typically airplanes don't like to hover, they want to 'fall out' You have to use the elevator and rudder to hold it vertical. Kind of like balancing a yard stick on the tip of your finger. However, when using elevator or rudder to hold it vertical, you usually have to change the throttle, as elevator / rudder changes will increase drag, and the airplane will start to 'fall'. Now because the airplanes propeller is turning one way, the airplane itself will want to turn the other way. (motor torque and all) This can usually be compensated for by using ailerons. But changing throttle as before will change the amount of ailerons needed to prevent torque rolling. Also, even changing aileron input will add drag, and require more throttle. 'Torque rolling' is on purpose not correcting the motors torque with ailerons. The airplane will then start to 'spin'. The hard part here is keeping track of it's orientation relative to you. Elevator and rudder inputs are always chaging as it's turning around.

Sorry to go on like this, but if it sounds hard, IT IS.. I'm maybe not quite as good a pilot as my friend, but I can definatly hold my own. I enjoy hovering very low to the ground as well. Problem is, there's no height for making mistakes.

Sorry, I stand corrected. I knew the helicopters used them and was assuming that rate gyro use on fixed-wing craft was more widespread than I thought it was.

An experimental sailplane from a few years ago:

http://members.cox.net/evdesign/page...lity_gyro.html

A "tips" page for a Futaba gyro:

http://www.rc.futaba.co.jp/hobby_en/...al/tech01.html

Maybe I've been reading too much about prototype UAVs and not enough about current model planes! - LOL.

Someone told me that these planes are so light they they barely work off bernuli effect at all. Is that true?

You've hit a hotly debated topic.

Some claim airplanes fly purely because of bernuli's style lift. Some claim they fly because of other lift created by bernuli's principle. Some state Angle of Attack. Others claim it's none of the above, and the rest claim a certain amount of all of the above.

I've heard the figure, 5% of a typical cessna's lift is created from bernuli's style lift. Seems right, as the below web page says a cessna would have to fly at 400mph if it were purely bernuli's lift.

I like the following web page myself:
http://www.allstar.fiu.edu/AERO/airflylvl3.htm

That's how I rationalize it. The airplane in this video is big (heavy) enough that it uses it's wing basically like a full scale plane does. When you get down to very small airplanes, like what we fly indoors, in the 6-10oz range, a 'flat plate' wing is more efficient than having a curved 'airfoil'. At this point, I would believe that angle of attack is pretty much the only factor in lift.

Yep, I do that sometimes :)

It does seem like most of it is from angle of attack, not to mention the huge control surfaces. It looks like almost a third of the wing is AILERON (thanks sharkie).

From what I remember, Bernoulli (thanks again) is still pretty controversial in general aviation as well as R/C.

When I took my ground school for my full sized pilots license, they taught the Bernoulli principle. It doesn't take too much to realize that it's not going to produce enough lift to fly a typical airplane. Our Grumman Traveller had a wing loading of 41 pounds per square foot of wing. The model in the video has a wing loading of about 12 OUNCES per square foot of wing. The difference is in the reynolds numbers. In other words, the air molecules don't scale down when you scale down the airplane. Even with a light wing loading like that, Bernoulli style lift only plays a MINOR part in lifting the plane. One other thing that isn't apparent is the fully symmetrical airfoil on the model. If the wing is the same shape top and bottom, how would air travel further over the top as opposed to the bottom? Obviously it couldn't. In normal flight, a positive angle of attack must be maintained in order to produce lift. This is what makes a plane fly.

What makes the model in the video fly when it's not in normal forward flight is raw power. The plane has a power to weight ratio of between 2.5 and 3 to 1. This allows it to "hang on the prop" and do a lot of the other maneuvers that are seen. Huge control surfaces, such as AILERONS allow it to maneuver very quickly at high speed, and allow it to maneuver at all at virtually zero speeds. Without the large surfaces, most of the maneuvers being flown could still be done, but the ones where the plane is moving very slowly would be much more difficult because there wouldn't be much control available.

Jim