52 votes
Accepted

Why do model aircraft fly and maneuver so differently from real aircraft?

It's partly inherent in the way things scale. If you double the length of the model, then the wing area (length times width) increases by a factor of 4, but the weight and volume (length times width ...
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  • 3,074
30 votes

Why do model aircraft fly and maneuver so differently from real aircraft?

Model aircraft are generally built with much lower wing loading and much higher power to weight ratios. This can be done partially because they have no real payload, and do not have to fly for long ...
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  • 3,711
24 votes

Why do model aircraft fly and maneuver so differently from real aircraft?

The laws of physics are not scale invariant. Area scales with the square of dimension while volume scales with the cube of dimension. Aerodynamic effects roughly scale with area. Mass roughly scales ...
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  • 1,614
20 votes
Accepted

What does this formulation mean?

What does mean "fl oz"? "fl oz" means fluid ounce (1 fl oz ≈ 30 ml), which is a unit of volume, as opposed to dry ounce, which is a unit of mass. How are they calculated the 30:1 ...
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  • 31.6k
19 votes
Accepted

Do quadcopter propellers break the sound barrier?

Almost certainly not. Given the comments specifying a $0.5$ inch radius (blade length,) that means the circumference of the path of the blade tips would then be $$2 \pi \cdot 0.5 \, \text{inches} \...
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  • 19k
16 votes
Accepted

How can an aircraft hover almost vertically?

The aircraft in the video is a remote-controlled (rc) airplane. Why it can "hover" is simply: The thrust generated by a big fan / rc-jet-engine is much higher than the weight of the plane. ...
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  • 3,687
13 votes

Why do model aircraft fly and maneuver so differently from real aircraft?

I'm not sure whether you are asking only about the physics involved, so hopefully this isn't too tangential - but one factor that's not really been touched on much is pilot input. In addition to ...
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  • 131
12 votes
Accepted

Has the FAA banned FPV for model aviation?

The FAA has interpreted the rules to mean that the operator must have a line-of-sight view of the model aircraft at all times, and that FPV does not qualify. Based on the plain language of the ...
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  • 69.8k
12 votes

How does this RC helicopter keep itself upright?

The rotor is gyro stabilized. The balance bar is the gyro. If the machine rolls right, the balance bar wants to stay in a level plane and generates a correction by influencing the rotor blades to go ...
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  • 107k
11 votes

What does this formulation mean?

Worth noting: when instructions say 2-cycle or 2-stroke oil, make sure you use this specific oil type. Just any oil will not be ok, in worst cases using wrong type of oil will cause the engine to ...
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  • 21.5k
10 votes
Accepted

Could you use radial blowers to propel a model aircraft?

Interesting question, and I can only answer in general terms because much depends on speculation. Short answer: use one central exhaust one big blower is better than two small ones one short flow ...
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10 votes

Why do model aircraft fly and maneuver so differently from real aircraft?

It depends on the pilot, too. I have seen a guy fly a 5-foot wingspan model of Piper Cub just as if it were the real thing. Much longer than necessary (for the model) takeoff run with lifted tail, ...
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  • 101
9 votes
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How does this RC helicopter keep itself upright?

The top rotor is a hinge offset rotor with a very serious stabiliser bar. These rotors exert torque via the mechanism in item 1 in this answer, and the body will align itself with the top rotor. But ...
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  • 58.8k
9 votes
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Where must the glider tow line connection be?

It needs to go just under the tip of the nose to have any chance. This connection is equivalent to the thrust line of an engine, except that because the connection isn't rigid, the longitudinal ...
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  • 107k
8 votes
Accepted

What is the maximum altitude allowed to fly a model plane/helicopter in England?

According to the UK CAA, a model aircraft is defined as: any ‘Small Unmanned Aircraft (SUA)’ (0-20 kg) used for sporting and recreational purposes and a ‘large model aircraft’ is defined as any ...
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  • 70.4k
8 votes

How do you control a 500mph model plane?

This video shows how such a model aircraft is controlled from the pilot's perspective: The pilot manually controls the plane from launch to landing, and also during ...
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  • 81
7 votes
Accepted

How can I get started on a winglet design for a small remote controlled aircraft?

For best results, put good flaps on the wing and forget using a winglet. If you insist on bending the wing up at its end, just continue with the tip airfoil and select the incidence such that your ...
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7 votes

What airfoil design is needed for a 4 m wingspan soaring plane?

First for those who wonder what F3J is: This is the FAI model aircraft category for thermal soaring. Quick answer: This answer describes what resources are available on the Net. Your choice of ...
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6 votes
Accepted

What is the maximum altitude allowed to fly a model plane/copter in Germany?

The maximum altitude you can operate your RC plane or copter vertically without any clearance from ATC or another government body is the upper limit of class G airspace in Germany, which is the first ...
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  • 15.5k
6 votes

Do quadcopter propellers break the sound barrier?

It's possible, but I would say unlikely. Supersonic propeller tips really mess with efficiency. The tip speed of many aircraft propellers is close to supersonic, and if not properly controlled can ...
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  • 67.3k
6 votes

Does the direction of counter-rotating props affect efficiency?

It might. Depending on how close to the wingtips your props are. If you put the props right at the wingtips, then the conventional rotation to minimize precession and torque actually decreases ...
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  • 2,376
6 votes
Accepted

Why is white light more visible than red and green on this Cessna model on a sunny day?

Navigation or Position Lights are meant to be used at night-time and can be used when precipitation or weather in general deteriorates to the point where the lights will help you identify an aircraft'...
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  • 15.5k
6 votes

Why is white light more visible than red and green on this Cessna model on a sunny day?

The navigation lights are meant to give away the airplane's orientation (i.e. which direction it is travelling) at night. The red and green lights are small. Their purpose is to be observable from a ...
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  • 39.3k
6 votes

Why do model aircraft fly and maneuver so differently from real aircraft?

See this very relevant discussion on Space.SE: Can a miniature Saturn V get to the moon and back? The square-cube scaling problem was already mentioned in other answers, but another important factor ...
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  • 6,197
6 votes

Where must the glider tow line connection be?

Lots to consider here. "Free-flight" model airplanes and gliders fly without any control inputs from a pilot whatsoever (and no automatic electronic stabilization systems either). One ...
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  • 17.4k
5 votes

How can an aircraft hover almost vertically?

Hovering is far easier and more common is propellor driven RC planes than jets. Very few RC jets have thrust vectoring, and even fewer have hovering capabilities. Propellor driven aerobatic RC ...
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  • 3,711
5 votes

Is it legal to build and fly an international aid drone?

Is it legal to build and fly a scale 1m:20cm Boeing C-17 for use in flying from the U.K. [...] Building an aircraft is likely not regulated (intellectual property laws still apply), it's probably ...
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  • 67.8k
5 votes

Why does this plane not pitch up after a dive?

Thank you for giving more information, but I still have to resort to speculation. Here are some things you might want to consider: A rear-mounted prop stabilizes the aircraft. Full throttle limits ...
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5 votes

Why does this plane not pitch up after a dive?

My vote is that the surfaces aren't rigid enough and get twisted so much that the control surfaces can't overcome the effect. How floppy (non-rigid) are the wings and the canard surfaces? The wing ...
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