Monday, June 26, 2017
Home » Bonus Content » Fixed or Collective Pitch, Small or Large, Paper or Plastic?

Fixed or Collective Pitch, Small or Large, Paper or Plastic?

Swinging its tail around to point cannons in your face, the scale Super Cobra hovering at eye level sucked you right in and inspired a whisper; “I’ve gotta have one of those!” And that is when the trouble began. You realize that you don’t know the first thing about flying RC helicopters, but imagine that your Hobbico NextStar training will translate to helicopters. Undaunted, you head to your local hobby store to dive head first into what has to be one of the coolest hobbies on the planet. The guy behind the counter calmly unleashes a “helistorm” of information, most of which hovers right over you because your mind got stuck on the first two decisions he suggested you make: should you buy a large or a small helicopter and should you opt for a fixed-pitch model or a more complex and costly model with collective controls? Gulp! These are the types of conundrums usually reserved for the checkout at your local grocery store.

These are the very questions I faced when I began flying helicopters in 2001 and I have some definite opinions about both. Fortunately, the product selection in model helicopters has blossomed over the past decade and you will have plenty of good choices. Making the right choice may mean the difference between becoming a proficient helicopter pilot and being sentenced to Air Hog status for life.

Over the years, I have built and flown dozens of helicopters, including fixed-pitch models, micro-sized models and scale mega-choppers as long as seven feet. Today, I only fly scale helicopters. My travels through the helicopter side of the RC hobby have helped shape my views about the type of helicopter that is most suitable for beginning pilots. After almost giving up on model helicopters because of my choice to try a fixed-pitch and then a micro helicopter, I can confidently say that larger collective-pitch helicopters provide the best platform for a pilot to become proficient with helicopters.

That is not to say that one cannot become expert by beginning with either a fixed-pitch or a micro helicopter. It can be done. But I believe the best chance for success lies with a larger helicopter boasting a full suite of controls.

Exceed Madhhawk fixed pitch rotor head. Notice how simple this rotor head looks in comparison to the others.

SMALL VS. LARGE

With the exception of coaxial helicopters, large helicopters are more stable and easier to control than helicopters roughly the size of a T-Rex 450 or smaller. Larger helicopters are easier to see, which allows you to read and react to transmitter inputs more quickly. Since larger helicopters are less twitchy than smaller ones, you will also find yourself fighting less and flying more with a helicopter that sports a rotor diameter of more than 45 inches.

From an expense perspective, it is possible to spend more on an Align T-Rex setup than a Thunder Tiger Raptor 30 setup. Once you crash your helicopter, getting parts for them can be equally expensive depending on your setup. Oh, and you will crash. It is very useful to embrace that horror before you jump into the heli pool. The question is whether you can minimize your crashes more effectively with a larger helicopter. I believe you can. With a 30-50 size helicopter, you can practice hovering with a training pod and get much more stick time than you can with a smaller electric over a typical practice session of an hour. I have found nothing that exceeds the effectiveness of training with a 50-size Raptor perched atop a spindly set of dowels and whiffle balls (e.g. a RotoPod).

Hirobo Turbulence D3 with collective pitch.

I hearken back to my nascent helicopter days with my second ship, the Ikarus Piccolo. I simply could not control the pint-size Piccolo long enough to learn much. I nearly gave up. That is when I purchased a Hirobo GPH 346 (roughly equivalent to a 50-size Raptor) and attached a RotoPod training gear set. Having spent hundreds of dollars on the full setup (stuff was more expensive back then), I was properly motivated to take my time. The glow setup allowed me to do just that. I spent many hours only a few inches off he ground practicing my hover technique at all orientations. Because the helicopter was relatively stable, I did not get into uncontrollable situations as easily. In addition, I was forced to seek out a wide open practice area and could not be tempted to steal away a few moments of flight in an enclosed or obstacle infested area as I have many times since then with a small electric helicopter.

The size of my first helicopter was key to sustaining my interest long enough to hone my skills. I was challenged enough to stay focused but was not discouraged at the prospect of another aerial wrestling match with a spastic little dervish. Plus, there was a huge “cool factor” with a larger helicopter. This is even truer nowadays when anyone can buy off-the-shelf toy helicopters. Deftly controlling a 50-size heli-copter does command respect from onlookers. Once you master the controls, it is neither a large nor expensive leap to retrofit your pod and boom with a nice looking fuselage. Or, if scale does not suit your tastes, you can move into the wild world of 3D flying.

E-flite Blade SR, a collective pitch heli.

The second helicopter I ever bought was the fixed-pitch Lite Machines Corona 110. The Corona is well designed, but it is designed to be simple. That means there is no collective control and, in my experience, less control overall. To make the helicopter rise and fall, you must manipulate the throttle. The pitch on the main rotors does not change.

FIXED PITCH VS. COLLECTIVE PITCH

I’ll digress for a moment on the differences between a fixed pitch and collective pitch system. The main blades on a fixed-pitch helicopter are mounted at a fixed angle of attack relative to the main shaft. You cannot change this angle so the only way to make the helicopter climb and descend is to change the speed of the rotor system. As you increase the speed of the rotor system it generates more lift, making the helicopter rise. Decreasing speed results in less left.

A collective-pitch rotor system allows the pilot to vary the blade pitch relative to the main shaft during flight. Rather than changing rotor speed to accomplish changes in altitude, the pilot need only apply collective control, which results in a corresponding increase or decrease in the angle of each blade. Changes occur in unison, giving nearly instant control response. Dramatic 3D aerobatics would not be possible without collective-pitch rotor systems. Collective-pitch rotor systems also make flying larger scale helicopters more practical and scale-like in appearance.

Align T-Rex 700 with collective pitch head.

Getting back to the fixed-pitch Corona, the upside of this arrangement is that crashes tend to cost less. There are fewer parts to break and there is less weight on the helicopter so the parts that are there can be sturdier. The downside is that a fixed-pitch helicopter is more difficult to master than a collective-pitch helicopter. The reason is that as you decrease throttle, say from a high hover, you are subtracting energy from the rotor system. With less energy, you have less control over the helicopter. As a result, you must anticipate the helicopter’s movements more than you do with a collective pitch helicopter of similar shape. Anticipation is one of the last skills mastered by helicopter pilots and the lack of it can lead to disastrous results for a new pilot.

To the contrary, collective pitch helicopters (especially ones set up with a constant head speed) offer much greater control over the helicopter from the ground up and back down. A collective pitch helicopter may cost more, but I believe the investment is well worth the return. If money is that much of a concern to you, either delay your purchase until you can afford a larger machine or purchase a good coaxial helicopter, like the Blade series from Horizon Hobby, and hone your close-in hovering and orientation skills. Although most coaxial helicopters are fixed pitch, what they lack in collective control, they make up in extreme stability. Stability is the key to generating confidence and skill in a new pilot. Without those characteristics, most new pilots never progress to their potential in the helicopter hobby.

NO ANSWER FITS ALL, BUT GO WITH THE ODDS

I am sure that some pilots will disagree with my approach. To those pilots I would say do what suits your fancy but do not ignore the indisputable facts: larger helicopters tend to be more stable than smaller ones and collective-pitch helicopters tend to be more easily controlled than fixed-pitch helicopters. In combination, I believe these attributes give new pilots the best chance at becoming comfortable and competent with helicopters. Now go train for that Super Cobra!

Michael Kranitz is the former CEO of RCUniverse.com. He entered the hobby in 1971 and has been flying helicopters since 2001.

Links

Align, distributed by Heli Wholesaler

www.heliwholesaler.com, (877) 454-9757

Blade Helicopters, distributed by Horizon Hobby

www.bladehelis.com, (800) 338-4639

Heli-Max, distributed exclusively by Great Planes Model Distributors

www.helimax-rc.com, (800) 682-8948

Ikarus USA

www.ikarus-usa.com, (239) 690-0003

Lite Machines

www.litemachines.com, (765) 463-0959

Thunder Tiger, distributed exclusively by Great Planes

www.ttamerica.com, (800) 682-8948