<p>The largest difference is that in <a href="https://en.wikipedia.org/wiki/Reynolds_number" rel="noreferrer">Reynolds number</a>, 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, a quarter-scale model will have a Reynolds number equal to one-forth that of the full-scale aircraft (in the same atmospheric conditions). The reason this matters is that airflow tends to transition from laminar to turbulent at a specific Reynolds number, so if one uses the same airfoil on the model as in the full-scale aircraft, then usually the performance will be different near stall (usually much worse). That is why reduced-scale models usually change to an airfoil that is designed for lower Reynolds numbers.</p>
<p>BTW, Intro to Aerodynamics by Anderson is excellent. That was my first textbook when I started aero engineering over 30 years ago.</p>

CC BY-SA 4.0
2020-08-04T22:10:59.293Z
2020-08-04T22:10:59.293Z
user3818628
<p>I am reading an aerodynamics textbook (Introduction to Aerodynamics by Anderson). I am still in the chapters that deal with subsonic aerodynamics, which seems to have a focus on life-sized manned aircraft. I am wondering: are there major differences in the consideration of aerodynamics when designing model aircraft as opposed to life-sized manned aircraft?</p>

CC BY-SA 4.0
2020-08-02T19:49:41.320Z
Does this answer your question: https://drones.stackexchange.com/questions/1231/do-aerodynamics-scale-for-model-aircraft
Jacob B
<fixed-wing><aerodynamics>
How do aerodynamics for small model aircraft differ from that of larger aircraft?
Flux
# How do aerodynamics for small model aircraft differ from that of larger aircraft?

(Asked by: username_0 on 2020-08-02)

I am reading an aerodynamics textbook (Introduction to Aerodynamics by Anderson). I am still in the chapters that deal with subsonic aerodynamics, which seems to have a focus on life-sized manned aircraft. I am wondering: are there major differences in the consideration of aerodynamics when designing model aircraft as opposed to life-sized manned aircraft?

**Tags:** fixed-wing, aerodynamics

> **Comments:**
> **username_1**: Does this answer your question: https://drones.stackexchange.com/questions/1231/do-aerodynamics-scale-for-model-aircraft  

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## 1 answers

### Answer by username_2 on 2020-08-04. Score: 5

The largest difference is that in [Reynolds number](https://en.wikipedia.org/wiki/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, a quarter-scale model will have a Reynolds number equal to one-forth that of the full-scale aircraft (in the same atmospheric conditions). The reason this matters is that airflow tends to transition from laminar to turbulent at a specific Reynolds number, so if one uses the same airfoil on the model as in the full-scale aircraft, then usually the performance will be different near stall (usually much worse). That is why reduced-scale models usually change to an airfoil that is designed for lower Reynolds numbers.

BTW, Intro to Aerodynamics by Anderson is excellent. That was my first textbook when I started aero engineering over 30 years ago.


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