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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
12 votes

Why does moving the centre of gravity forward increase stability of a plane?

TLDR; Aft CG means stalls are unrecoverable! Why is CG relevant? The plane's elevator is the control surface for pitch angle. The elevator is its own proper wing, and as such only has a certain amount ...
Kenn Sebesta's user avatar
  • 1,892
10 votes

Drones capable of smooth plane/bird-like flight

You might be able to write custom flight control software for a multi-copter that would simulate this. You might get close just by radically limiting the pitch and roll rates and being gentle on the ...
Robin Bennett's user avatar
9 votes

Drones capable of smooth plane/bird-like flight

(Edit: The original version of this question asked about "drones" in general. This answer was based on the question pre-edit, hence the clarification of drones vs. quadcopters.) First, a ...
HiddenWindshield's user avatar
9 votes
Accepted

Can I run two motors off of one ESC?

Technically, you could connect 2 motors, and it will probably work if they're exactly the same size and model, and have identical props on them. However, if the motor-prop combinations are ...
FlashCactus's user avatar
  • 2,997
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
7 votes
Accepted

Do I need CW or CCW props for my plane?

The decision between CW (clockwise) and CCW (counterclockwise) propellers has to do with the direction your motor/engine will spin, not really in regard to where you're putting the engine on the plane....
ifconfig's user avatar
  • 6,008
7 votes
Accepted

What obstacles are there in making ultra long range model aircraft?

So many different issues, I study a lot of the FAA regulations closely but have contemplated this same question a few times. The power and weight of gear is heavy, so to make it all the way around is ...
FunHog.me's user avatar
  • 1,068
7 votes

Do laws on 'drones' in Australia apply to fixed wing model aircraft?

In case you would prefer an answer with citations (as different regulators have different views on this), at the following link is CASA web page regarding "Recreational unmanned aircraft (...
Kralc's user avatar
  • 6,046
7 votes
Accepted

What would a basic fixed-wing electronic setup look like?

The main things you need are a motor, battery, electronic speed controller (ESC) and servos. The ESC sits between the battery and motor, and it also has a thinner cable that goes to the receiver. The ...
Robin Bennett's user avatar
6 votes
Accepted

Is it feasible to use an RC car transmitter/receiver to control an RC plane?

Maybe! Let's take a look at what parts from the RC car we might be able to reuse for an RC plane. You haven't shared any specific details about the RC car you're looking to salvage parts from or the ...
ifconfig's user avatar
  • 6,008
6 votes
Accepted

Do laws on 'drones' in Australia apply to fixed wing model aircraft?

Strictly speaking, "Drone" refers to any unmanned aircraft that can fly autonomously. Usually, however, a drone is classified as any unmanned aircraft even if it requires a remote pilot's ...
Jacob B's user avatar
  • 5,792
6 votes
Accepted

When flying, how can I identify the orientation of a distant fixed wing model aircraft?

The main way is through 'situational awareness'; if you are flying the aircraft, you should have an idea of what is it doing based on what it has done, and what you have commanded it to do. For ...
Kralc's user avatar
  • 6,046
6 votes
Accepted

How close can a drone be to a wind turbine in Germany?

very intersting question I am in your situation as well flying LOS of course: in the EU assuming you are operating an A3 Open Category UAS, according to EASA, we should keep the drone (fixed wing or ...
Luca Spuntoni's user avatar
5 votes

Is it feasible to use an RC car transmitter/receiver to control an RC plane?

Back in the early days of RC, people only had single channel radios, and vintage models were designed to be flown with only the rudder (and a small amount of fuel in the tank to limit the maximum ...
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
5 votes

Can I run two motors off of one ESC?

From a technical standpoint it is possible, but there are a number of considerations: Only need one ESC so lighter ESC needs to have a higher current rating to fully power the motors Motors must be ...
Kralc's user avatar
  • 6,046
5 votes

What should I use to cover this plane with?

How about the thin white polythene/polyethylene from carrier bags or bin liners? I think you could stick it on with a foam-safe contact adhesive such as UHU POR. Alternately, you can save weight from ...
Robin Bennett's user avatar
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
4 votes

Can I run two motors off of one ESC?

You can, but it's not recommended. First of, you will need an ESC that can handle twice the current of what one motor consumes. The motors will also be seen as one single motor by the ESC, so of one ...
Hannes Hultergård's user avatar
4 votes

Do I need CW or CCW props for my plane?

If a plane has a preference, it's probably for a clockwise prop. This dates back to before electric motors, when people hand-started glow motors. You'd kneel next to the plane, hold the fuselage with ...
Robin Bennett's user avatar
4 votes
Accepted

How to determine the minimum thrust to weight ratio for a fixed-wing aircraft?

I'm afraid it's not that simple. As you mention, planes can fly with a fairly low thrust to weight ratio. Obviously gliders can fly with no power at all, so there's no critical lower-limit. The other ...
Robin Bennett's user avatar
4 votes

What would a basic fixed-wing electronic setup look like?

The image below shows a fairly basic fixed wing electronic configuration. Depending on your design you might not need it all, and for more complicated builds with flaps and retractable gear you would ...
Kralc's user avatar
  • 6,046
4 votes

What would a basic fixed-wing electronic setup look like?

Summary The necessary electronic components: Transmitter & receiver, ESC, motor, servos. (yes, it really is that simple) How they are linked together: basically; battery plugs into ESC input, ...
Jacob B's user avatar
  • 5,792
4 votes

Can a BLDC motor meant for a multi-rotor be used for a fixed-wing aircraft?

Yes you can, I have a few small planes using race quad motors that I had bought as spares. They work fine, although there are a few minor things to note. The main thing to check is the speed rating of ...
Robin Bennett's user avatar
3 votes

Drones capable of smooth plane/bird-like flight

The premise of your question is based on fairly limited observation of aviation. First there are many fixed wing "drones". They just haven't been as prevalent in the consumer market as in ...
Chris Stratton's user avatar
3 votes

Picking the right prop pitch for my plane

The key here is to understand pitch speed. The pitch of a prop is how far it will advance in one rotation if there's no slip, so a 5" pitch prop spinning at 15,000rpm will advance 75,000 inches ...
Robin Bennett's user avatar
3 votes

Is it feasible to use an RC car transmitter/receiver to control an RC plane?

This is an interesting idea and I think it could work. There are, however, a few things that are worth considering. First of all, a controller for an rc car will usually have only 2 or 3 channels. ...
Jacob B's user avatar
  • 5,792
3 votes
Accepted

Is it possible to control an RC plane using reaction wheels?

Yes, it would! A YouTuber, Thomas Stanton, has actually built a helicopter controlled with reaction wheels in this video! However, for a fixed wing aircraft, you would also have to consider the ...
Drones and Whatnot's user avatar

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