The parts you can select for a race quad are vast and extremely varied. Frames, motors, batteries, and other components come in a huge number of varieties. If you want to build a quadcopter to get started with racing, you need to make a lot of decisions. Your first step in navigating this landscape might be to look at the specifications for race classes. Today, those class specs won’t offer much guidance.

For FPV quad racing, it’s hard to find consistent specifications. Some racing organizations like DRL and PAL don’t publish their specs at all. Others like the IDRA are so vague as to be useless. These organizations don’t offer any kind of open participation, but they’re missing an opportunity to lead. MultiGP is trying to fill this gap and doing a great job getting specs published and available so that small, local chapters can all work from the same material. Without the work they’ve done so far, we’d have nothing consistent to work from at all—I want to be sure to recognize that. But MultiGP’s specs have some flaws that need addressed if we’re to grow the sport from the ground up.

MultiGP’s class spec page states a few reasons why classes are important, but we think the reasons for a class spec go well beyond these few simple points. Our recent article “Race Specs: What’s the Point?” is an important precursor to many of the points we’re making in this one. Be sure to take a look.

After reading this article, be sure to join in on the discussion here, on Reddit, or RCGroups!

Writing a Better Spec

What matters most in our class specs? It’s a question the community as a whole has to come together to answer. Here’s where we would start.

Limit Performance

race specs fpv

Our group’s spec races provide close competition. This race was decided by 0.2s.

Even MultiGP gives number one priority for a spec to “… level the playing field so one pilot doesn’t have an advantage over another by using more powerful equipment.” Unfortunately, this is also the biggest problem with the current classes: they fail to effectively limit performance.

The existing classes limit weight to a maximum, frame size to a maximum, and the maximum diameter of props. The battery is limited to number of cells, providing a minor controlling factor. This leaves an immense amount of room for ever more powerful motors, lighter frames, higher pitch props, or more powerful battery chemistry. Nothing in the spec actually limits performance. As a result, expensive race quads built just two years ago are completely outclassed by something built today on a budget. We need to do a better job authoring classes with a true performance cap. This might be done by placing a maximum on actual output force (Kg of thrust), and by instituting a weight minimum.

While there’s a place for a single “open” class, many of the benefits that can be gained from having a class spec are achieved through performance limiting: leveling the field, setting up various types of race experiences, encouraging innovation, and controlling costs. (Each of these is explored in detail in “Race Specs: What’s the Point?“)

Focus on Effects, not Methods

Nothing should be limited specifically by technology unless absolutely necessary. A technology requirement can stifle the market and prevent innovation. MultiGP’s “Tiny Whoop” class specifies brushed motors, which discourages manufacturers from developing motor technology for this class. The brushed motor restriction was likely put in place in order to limit performance—a better solution would be to use another metric to equalize competitors but allow technology growth, such as thrust.

A good spec focuses on a desired end result, not the specific process used to achieve it.

Don’t Close the Door on Manufacturers

fpv racers

A “SPEC class” doesn’t have to result in a fleet of identical machines. Performance-based classes can have the same effect without the requirement of purchasing from a parts list.

MultiGP’s current “SPEC class” specifies exact parts. The goal of the SPEC class is a great idea: performance limiting taken to a high degree. However, the current implementation favors certain manufacturers to the exclusion of all others—which discourages innovation and development for companies in the spec (whose newer products won’t be homologated) and those outside the spec (who are prevented from entering it). Work that’s been done setting up this class doesn’t need to be thrown away, though—it can be set up as a performance-based spec where the selected parts all qualify. This way, any manufacturer can decide to contribute parts that meet the spec at any time, and racers will get a wider variety of options. The MultiGP branding that’s applied to homologated parts will offer a quick way to verify performance, helping buyers make simple purchasing decisions and speeding up spec check for race organizers.

Another important effect of a parts list: it often prevents pilots on low budgets from participating. If a class has a performance cap, anyone with a machine that performs lower than the spec is still allowed to race. Even though a racer would be at a disadvantage in doing this, many do so just to get more competitive experience with course flying at events. This is a great benefit for beginners and casual racers, but is specifically disallowed if a parts list is in use.

Be Only as Restrictive as Necessary

If a restriction isn’t helpful, it shouldn’t exist. For example, a local chapter may have a good reason to require members to use Raceband, but this doesn’t make sense at the global level. If analog video frequencies are too tightly restricted, manufacturers may encounter resistance in new product with the coming of digital video feeds.

It’s important to approach specs as openly as possible, writing restrictions only where they are absolutely needed. This allows the widest possible range of equipment to be included, which is a great benefit to local groups and racers that run on a budget. There’s a resistance to narrow classes in local groups because people don’t want to re-invest, and a spec that aims at including these groups needs to be sensitive to that. Local group racing shouldn’t require big budgets.

Be Easily Testable

Race organizers need a simple method of testing for conformance at an event. For small, local groups, this can’t require disassembly or specially-calibrated testing equipment. Any requirement should be able to be confirmed by a quick visual inspection or by small and inexpensive test equipment.

The MultiGP specs do a reasonable job of this already, since the size/weight restrictions can be checked with a ruler and a scale. Only VTx power requires more sophisticated equipment, and local chapters can probably get by without strictly checking for this. If we build a performance-based spec and need to measure total thrust output, this task will become more difficult. Organizers will need some kind of test rig. This doesn’t exist today and will need to be developed. Individual racers need this equipment, too, so they can confirm their setup meets regulation before going out to the field.

Provide Variety

race sight lines

Providing variety in race types adds more interest for pilots and spectators alike. This course had three separate race lines for different classes of events.

Class specs shouldn’t be developed individually, but as a whole package. Each one should focus on a different kind of experience and have different possibilities. Spec designers should ask: “What does this accomplish or provide that’s unique?” If two classes provide roughly the same experience at different performance levels, there’s more work to do. These can be relatively simple: raw speed, maximum agility, endurance, or easily set up indoors are all valid ideas that could be part of the intended experience. Class specs should be written with these in mind, using tighter or more lenient regulations as needed.

Getting There

A revised set of classes won’t succeed without buy-in on many different levels. The first line are the organizing bodies; a group such as MultiGP which has a wide audience and ready method of distribution. To succeed, a group with this kind of reach absolutely must be on board. Once the spec is developed and accepted there, local chapters must decide to accept and adopt it. The more chapters there are using the spec, the more recognition and credibility it gains. Other chapters then see it as a precedent to be followed and its influence grows. Finally, manufacturers will get on board organically when the market demands it.

I can’t stress enough that we have to get there together. There’s a good reason this article isn’t providing a recommended set of classes—we don’t want to split the community. If the organizers aren’t on board, or the pilots don’t agree with the direction that organizers have taken, we end up in a classic competing standards situation. The benefits of universal adoption will never materialize (or quickly evaporate) if groups take different paths. The community needs to coalesce around a single organizing body and accept the standards it publishes. Of course, the community also needs to have a strong input into the direction of this body. At this moment, MultiGP seems to be best positioned for this.

That said, we strongly believe the end goal will include:

  • classes designed for safety; each will have a maximum weight and a maximum VTx power
  • a single “open” class with few restrictions
  • all other race classes are performance-based, likely by defining a minimum weight and a maximum thrust output
  • performance caps are set so equipment is operated within its rated specification (for example, to prevent overheating batteries under normal race conditions)
  • specific technology references, such as “brushed motors”, are avoided
  • classes that are unique: one that’s power-oriented, one that makes endurance racing possible, etc.
  • simple restrictions that can be checked quickly

What Can We Do?

To get to a better spec, we must, as a community, ask for it. Unless there’s a desire for this kind of change, we won’t get one. We must make it known to race organizers that we want something better. Tell your race director. Write to MultiGP. Join in on the community discussion, or start a discussion topic on another board. Feel free to link to this article (and “Race Specs: What’s the Point?“) if it helps you make your argument.

We must also discuss exactly what our better spec would look like and come to consensus. These discussions can be local, regional, online—almost anywhere. Our ideas will keep the process moving forward. The best spec benefits us all, so it should be designed with community input. If you have ideas, make your voice heard. Present a logical case and back it up with examples if you can—but simply stating preferences can also help direct more subjective choices.

If we do get a better spec written and published, there will still need to be adoption in order to realize the benefits. Promote the results. Get groups on board. Push the manufacturers to take notice.

Class specs can be a powerful tool for innovation and bringing people together, but it will only happen if we make them our own.

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