How to choose a quadcopter | Articles | Gadgets, gifts and accessories

Not so long ago, to send an air­craft, even its mod­el, into flight, an accu­rate cal­cu­la­tion of aero­dy­nam­ics, engi­neer­ing cal­cu­la­tion, as well as the remark­able skill of the per­son who con­trols it, were required. But with the devel­op­ment of elec­tron­ics, it has become tech­ni­cal­ly pos­si­ble to make almost any­thing fly, as long as it has suf­fi­cient engine thrust.

Thanks to this, the wide dis­tri­b­u­tion of radio-con­trolled quadro­copters and mul­ti­copters became pos­si­ble.

Quad­copter in flight

So, let’s start with what is, for exam­ple, a typ­i­cal quad­copter. This is a mod­el with four elec­tric motors, each of which dri­ves a pro­peller, the thrust of which is direct­ed down­wards. Half of the engines, at the same time, rotate in one direc­tion, half in the oth­er. Due to the dif­fer­ence in the speed of rota­tion of the engines and their thrust, the quadro­copter is tilt­ed and rotat­ed around the ver­ti­cal axis. All this requires effi­cient motion and posi­tion sen­sors, as well as pre­cise motor con­trol. Actu­al­ly, from the com­plex­i­ty of con­trol sys­tems and envy of the class of the device.

In addi­tion, there are so-called mul­ti­copters, that is, devices with more than four pro­pellers. Gen­er­al­ly, mul­ti­copters have bet­ter pay­load capac­i­ty and flight sta­bil­i­ty.

So, what char­ac­ter­is­tics will help to dis­tin­guish dif­fer­ent class­es of these devices?

Features of control and management

In our opin­ion, it is con­trol and man­age­ment that pri­mar­i­ly dis­tin­guish­es expen­sive and cheap quadro­copters.

First of all, it is worth under­stand­ing how the oper­a­tor con­trols the drone.

The usu­al case is when con­trol is car­ried out using the trans­mit­ter of the equip­ment. For full con­trol, four axes are need­ed: total thrust (height), turn, tilt for­ward-back­ward, tilt left-right.

DJI Phan­tom trans­mit­ter with tablet

At the same time, the trans­mit­ter itself should be com­fort­able enough. The small-sized options, rem­i­nis­cent of a gamepad, are worse than the full-sized options in this cri­te­ri­on. For mod­els with cam­era gim­bal con­trol, cam­era con­trol is required.

Some­times, a smart­phone with a spe­cial pro­gram con­nect­ed via Wi-Fi to the quadro­copter can be used as a trans­mit­ter.

In addi­tion to the type of con­trol pan­el, the pres­ence of elec­tron­ic assis­tants mat­ters.

In bud­get mod­els, in fact, “man­u­al­ly” you have to con­trol the move­ment of the device in the air, which requires a cer­tain skill and skill.

On more com­pli­cat­ed mod­els, the so-called hov­er­ing mode appears, thanks to which “taxi­ing” is not required to hold the device.

The most advanced mod­els have a more com­plex con­troller that imple­ments the fol­low­ing func­tions:

• GPS posi­tion­ing. Quad­copters can even have an autopi­lot func­tion, that is, fly­ing along way­points. And such a func­tion as a return to the start­ing point is a neces­si­ty for expen­sive mod­els.
• a large num­ber of con­trol modes. For exam­ple, a quad­copter can be locat­ed on one side of the oper­a­tor, or it can main­tain its ori­en­ta­tion rel­a­tive to the car­di­nal points.
• set­ting flight para­me­ters on the com­put­er. As you can under­stand, the quad­copter con­troller per­forms the func­tion of flight sta­bi­liza­tion, lim­it­ing the range of its move­ment. Accord­ing­ly, by con­nect­ing the quad­copter to a com­put­er, you can change the lev­el of these restric­tions (for exam­ple, the angle of incli­na­tion), mak­ing the behav­ior of the mod­el more or less aggres­sive.

For exam­ple, DJI releas­es the Naza‑M con­troller, which is installed in its own quad­copters, or sold sep­a­rate­ly for use in “self-assem­bled” drones.

DJI Naza‑M Quad­copter Con­troller

Final­ly, the obsta­cle avoid­ance func­tion is very use­ful, thanks to which you will not smash your dear fly­ing friend against the wall. It is imple­ment­ed using cam­eras for view­ing the sur­round­ing space and oper­ates in the vis­i­ble range.

Togeth­er with them, ultra­son­ic loca­tors can be used, as in bats.

Ultra­son­ic posi­tion sen­sors quad­copter DJI Phan­tom 4 Pro

Dimensions

Quad­copters and mul­ti­copters come in a vari­ety of sizes.

Con­ven­tion­al­ly, they can be divid­ed into three class­es:

1. Large quad­copters. These mod­els are designed for car­go trans­porta­tion, recon­nais­sance, or aer­i­al pho­tog­ra­phy on large cam­eras. The price of such devices is always high, since in this class there are no quad­copters-toys designed sole­ly for enter­tain­ment.
2. Medi­um. This is the most com­mon class, which has the best com­bi­na­tion of price and fea­tures. There are mod­els for aer­i­al pho­tog­ra­phy and for sim­ple “fly­ing” mod­els. The price of bud­get and expen­sive mod­els can dif­fer by an order of mag­ni­tude, and the func­tion­al­i­ty also dif­fers accord­ing­ly.
3. Com­pact, “mini” mod­els. This class does not fea­ture high cam­era image qual­i­ty or long flight times, but is great for indoor fly­ing (home, office, gym). They do not require a lot of space for trans­porta­tion and use, but they over­come the wind worse due to their size. In addi­tion, an ultra-com­pact quad­copter is less vis­i­ble at a dis­tance, and because of this, it will be more dif­fi­cult to dis­tin­guish between its rear and front.

Camera

In prin­ci­ple, a quad­copter may not have a cam­era, and then it will be pos­si­ble to con­trol it nor­mal­ly only with­in sight.

The next stage is when the cam­era is inte­grat­ed into the quad­copter. It is clear that such a solu­tion is bud­getary, the cam­era is not pro­tect­ed from vibra­tion, and there­fore the pic­ture qual­i­ty will leave much to be desired. Such cam­eras are typ­i­cal for ama­teur and rac­ing mod­els.

Quad­copter Par­rot Bebop Drone with inte­grat­ed cam­era

In some cas­es, the cam­era can rotate rel­a­tive to the quad­copter body, but only before the flight, and not dur­ing it. This solu­tion is slight­ly bet­ter than the pre­vi­ous one, but still far from ide­al.

The most advanced option is a cam­era on a sta­bi­lized gim­bal that can be con­trolled remote­ly, that is, the cam­era can turn in flight. As a rule, such cam­eras have a good matrix, optics and shoot video in high res­o­lu­tion. The appear­ance of remote­ly con­trolled gim­bals on the mar­ket has become one of the fac­tors in the spread of aer­i­al pho­tog­ra­phy from quadro­copters.

Cam­era and gim­bal DJI Phan­tom

Of course, what hap­pens in the video record­ing and pho­tos from the cam­era is also impor­tant.

On bud­get mod­els, the video is sim­ply record­ed on a mem­o­ry card, and you can watch it only after the drone “lands”.

But, of course, it is much more inter­est­ing when the pic­ture is not only record­ed on a mem­o­ry card, but also trans­ferred to the oper­a­tor. This allows you to bet­ter con­trol the flight and the record­ing itself. All the great films shot from a quad­copter could hard­ly be made with­out watch­ing the image dur­ing the flight.

Flight time and distance

This is one of the eas­i­est char­ac­ter­is­tics to under­stand, but not the eas­i­est to imple­ment.

With the flight range, every­thing is more or less clear — a large-capac­i­ty bat­tery is enough, plus effi­cient engines. Increas­ing the reserve of bat­tery capac­i­ty is one of the pos­si­ble ways to tune fac­to­ry mod­els. How­ev­er, it is clear that the thrust of the engines to lift addi­tion­al bat­ter­ies must be con­sid­er­able.

But with a range it is more dif­fi­cult, because you need not only to trans­mit con­trol sig­nals from the remote con­trol, but also to receive a pic­ture from the cam­era. How­ev­er, for exam­ple, in DJI pro­fes­sion­al mod­els, the con­trol range is 5 kilo­me­ters (in Europe, the same mod­els deter­mine their loca­tion and refuse to fly fur­ther than 3.5 kilo­me­ters).

Engine type

There are two types of motors used in quad­copters: brushed and brush­less. Brush­less ones are bet­ter — they have less fric­tion between elec­tri­cal parts, and there­fore they are much more durable. How­ev­er, they are also more expen­sive.

So, quadro­copters have a large num­ber of char­ac­ter­is­tics and fea­tures, but despite this, there are not so many func­tion­al class­es.

Let’s talk about what class­es of quadro­copters exist.

Budget quadcopters

As the name implies, they are sig­nif­i­cant­ly lim­it­ed in capa­bil­i­ties.

First, they have an aver­age flight time of about 10 min­utes.

It uses com­mu­ta­tor motors, which, as we know, are not very durable.

Of course, the built-in cam­eras on such quadro­copters do not dif­fer in par­tic­u­lar image qual­i­ty.

One of the most pop­u­lar man­u­fac­tur­ers of such mod­els is Syma. It offers a huge range of drones at a very attrac­tive price.

Syma X5 quad­copters are one of the most pop­u­lar

Of course, you need to under­stand that bud­get quad­copters can serve either for enter­tain­ment or as a tran­si­tion­al stage to more seri­ous class­es.

Quadcopters for aerial photography

Quad­copter Gopro Kar­ma

It was with the advent of this class of devices that quad­copters became as pop­u­lar as they are now. To be pre­cise, DJI, with the famous Phan­tom quad­copter, was the first to offer an out-of-the-box solu­tion suit­able for aer­i­al pho­tog­ra­phy. First of all, this became pos­si­ble thanks to the Naza‑M con­troller, which per­fect­ly sta­bi­lizes the quad­copter in the air, as well as the per­fect cam­era sus­pen­sion, which allows you to move the cam­era in flight, plus it addi­tion­al­ly com­pen­sates for the vibra­tion of engines and pro­pellers.

racing models

These mod­els are most often assem­bled by hand from indi­vid­ual com­po­nents, and have high speed, maneu­ver­abil­i­ty and the most light­weight yet durable con­struc­tion. To achieve these qual­i­ties, blades and a frame made of car­bon fiber are used.

RTF rac­ing quad­copter Walk­era F210

Quad­copter races are held in FPV (First Per­son View) mode. To do this, the oper­a­tor is put on a spe­cial hel­met — glass­es, on which the pic­ture from the drone’s cam­era is dis­played. The cam­era is rigid­ly fixed, but not from a bad life, but for bet­ter flight con­trol and sim­plic­i­ty (light­ness) of the design.

For exam­ple, the speed of the Walk­era Furi­ous 320 rac­ing quad­copter can reach 33.3 m/s (for com­par­i­son, the DJI Phan­tom flies at a speed of 20 m/s).

conclusions

The vari­ety of quad­copters on the mar­ket is very large, but despite this, the choice is quite sim­ple to make if you are guid­ed by rea­son­able con­sid­er­a­tions.

Despite the fact that the fun­da­men­tal struc­ture of quadro­copters is the same, they are quite clear­ly divid­ed into class­es. There­fore, know­ing your bud­get and read­ing our arti­cle, you will make the right choice.

Mini glossary of terms

RTF (Ready To Fly) — an air­craft mod­el or quadro­copter, sold ful­ly assem­bled and com­plete enough to fly

sus­pen­sion — a device respon­si­ble for mount­ing, move­ment and sta­bi­liza­tion of the quadro­copter cam­era.

Col­lec­tor motor — an elec­tric motor in which the alter­nat­ing cur­rent sup­ply to the wind­ings is pro­vid­ed by a mechan­i­cal con­tact of the col­lec­tor. The dis­ad­van­tage is the pres­ence of fric­tion in the col­lec­tor con­tacts, as a result of which they wear out and the engine fails.

Brush­less motor — an elec­tric motor in which the alter­na­tion of the cur­rent sup­ply is pro­vid­ed by exter­nal devices. It is more durable than the col­lec­tor and has a high­er effi­cien­cy com­pared to it.