Skip to main content
15 votes
Accepted

Do aerodynamics scale for model aircraft?

Aircraft do not scale linearly, for a number of reasons. Most aerodynamic equations include a speed squared term. If you halve the speed, you only get a quarter of the lift and drag, so models tend ...
Robin Bennett's user avatar
8 votes

Do aerodynamics scale for model aircraft?

Elaborating on @Robin's answer with the full effects of the cube-square law. If we were to construct a model aircraft at half the length of a full aircraft, the model would: Have half of the ...
Krish's user avatar
  • 752
5 votes
Accepted

Question about Mars Ingenuity helicopter's wide-chord blades

Longer blades are more efficient, but it's only practical to a point. Blades have to withstand high RPM, be balanced, and be light. Also the linear velocity of the tip of the blade increases a ton if ...
Simon Fox's user avatar
  • 148
5 votes

Question about Mars Ingenuity helicopter's wide-chord blades

Increasing blade chord can give more lift, but only up to a point. Helicopter blades are pushing a column of air downwards, accelerating it from stationary to whatever speed is necessary. Each time a ...
Robin Bennett's user avatar
5 votes

How do aerodynamics for small model aircraft differ from that of larger aircraft?

The largest difference is that in Reynolds number, which is the same issue that wind tunnel models have. The Reynolds number is linear in length, which for the wing is the chord length. So for example,...
user3818628's user avatar
4 votes
Accepted

How do I calculate thrust for a quadrocopter?

The usual way to calculate exact thrust is actually experimentally, through testing on a thrust stand. There are countless factors that may influence the performance of your particular motor and ...
FlashCactus's user avatar
  • 2,997
4 votes
Accepted

How to determine the correct specification of servo for a control surface

Most forces in aerodynamics are proportional to area, speed squared, air density and a 'coefficient' that describes how efficient your object is. There's also usually a 1/2 for obscure theoretical ...
Robin Bennett's user avatar
4 votes
Accepted

What is the typical glide ratio of Kline-Fogleman airfoils?

This paper (AE-74-1054-1) from the University of Tennessee has a graph on page 15 showing the best they managed was 1:17 with the step on top and 1:8 with the step on the bottom but these were at a ...
Robin Bennett's user avatar
3 votes
Accepted

How do thrust requirements change as a multirotor leaves ground effect?

To fly above ground effect, you need thrust equal to the weight of the aircraft (or slightly more, as you want to climb). Ground effect doesn't hold aircraft down, it just makes it easier to fly when ...
Robin Bennett's user avatar
3 votes
Accepted

How to account for propeller (fixed pitch) in model aircraft performance calculations?

The easiest way to account for propeller thrust, is just by using basic physics. Being $P$ the power supplied to the propeller, the propeller changes this power in a thrust $T$ moving the airplane at ...
sophit's user avatar
  • 271
3 votes

What is the most thrust dense copter configuration?

Assuming you can only use up to four motors (because if you used six, eight, or even more you could just lift something with brute force) the most thrust dense configuration would probably be a ducted ...
Jacob B's user avatar
  • 5,792
2 votes

How do I calculate thrust for a quadrocopter?

Many common motors will come with a data sheet for a range of voltages and propellers, such as the data sheet at the bottoms of the description for these motors: https://www.quadcopters.co.uk/iflight-...
Drones and Whatnot's user avatar
2 votes
Accepted

Using BMP280 as an altimeter for CanSat

Sensitivity Barometers are quite sensitive, however "air pressure" is very much not consistent. Generally, you can expect about one meter accuracy, maybe a bit less, from a barometer, once ...
Brydon Gibson's user avatar
1 vote
Accepted

How much torque do I need for the servomotor which turns my canard?

The standard equation for aerodynamic forces is a half, times the density of air, times the speed squared, times the area, times an aerodynamic coefficient. $$L=\frac{1}{2}\cdot\rho\cdot v^2\cdot A\...
Robin Bennett's user avatar
1 vote

How to couple panel method velocities with boundary layer equations to obtain viscous pressure and lift coefficient?

Hi Mate please see the HFLR5 Site and software that includes also calls to xfoil. As we know what you are asking is not an easy task. The following example is for an airplane with NACA 2410 airfoil, ...
Luca Spuntoni's user avatar
1 vote

Do aerodynamics scale for model aircraft?

For a given constant global density, mass grows with the cube of the linear dimension. Concerning lift, all other things equal, lift grows linearly with the wing area, and the wing area grows with ...
xxavier's user avatar
  • 111

Only top scored, non community-wiki answers of a minimum length are eligible