Category: Blog

A roundup of the questions we’re asked most often, gathered in one place.

How do I know what size gear my model needs? Check the manufacturer’s recommended engine displacement or size class first, and measure your existing mounting points against our size charts if you’re unsure. See Day 1 for the full walkthrough.

Is carbon fibre gear a straight swap for aluminium? Usually yes in terms of mounting, but always check dimensions and rated weight range rather than assuming — see Day 2 for the fuller comparison between the two materials.

Can I cut gear down to a narrower width? Many designs are intended to be trimmed this way, but not all — check the specific product description first, and see Day 11 for a full guide to doing it properly if your gear is designed for it.

How do I know if my gear needs replacing? Look for hairline cracking, asymmetric flex between the two legs, or elongated mounting holes — the full checklist is in Day 4.

Do I need to do anything special after a hard landing? Yes — a proper check before flying again, even if the landing “felt fine.” Day 19 covers exactly what to look for.

What torque should I use on gear mounting bolts? Firm and secure by feel, with thread-lock for security, rather than maximum tightness — over-torquing is a common cause of cracked mounting points. See Day 17.

Does wheel choice actually matter for gear longevity? Yes, more than most flyers expect — wheel size and softness affect how much shock load reaches the gear leg on each landing, particularly on grass. See Day 7.

How often should I inspect my landing gear? At minimum, at the start of each season and after any unusually hard landing — a quick check takes minutes and catches almost every issue covered across this whole series before it becomes a real problem.

Got a question that isn’t covered here? Get in touch — we’re always happy to help you get the right part for your specific model.

Take a look at our Carbon fibre undercarriage for 70 size nitro or electric models – Wide Fuselage for a solid example of correctly sized gear.

Older models with plenty of life left in the airframe are often excellent candidates for a component refresh, and landing gear is frequently one of the highest-value upgrades available.

Start with an honest condition assessment, not just of the gear but of the mounting points it bolts to — there’s limited value fitting a premium new carbon fibre gear to mounting rails that are themselves worn, cracked, or otherwise compromised from years of use. A genuinely tired mounting area may need reinforcement or repair before new gear will deliver its full benefit.

Weight and balance may have drifted from the original design over the model’s life, particularly if radio gear, battery, or engine have been changed at some point along the way — it’s worth rechecking your model’s current all-up weight against your intended new gear’s rated range (see Day 1) rather than assuming the original specification still applies unchanged.

A gear upgrade is a good moment to address other ageing components at the same time, since you’re already working in that area of the model — tail wheel assembly (Day 16), wheel pant mounting (Day 6), and general fastener condition (Day 17) are all worth a look while the model’s apart for gear work, rather than as separate future jobs.

Don’t assume newer automatically means a straightforward swap. Manufacturing tolerances and mounting standards can shift subtly over the years even within a broadly similar product category — always check current dimension charts against your specific model’s mounting points (see Day 27) rather than assuming a modern part will match an older airframe’s original specification without checking.

An older model with a fresh set of carbon fibre landing gear, properly fitted, can genuinely fly and land like new — it’s one of the better value upgrades available for a model that’s otherwise still got plenty of flying life left in it.

For a real-world example, have a look at our EXTRA 300 50CC Carbon Fibre undercarriage.

Most landing gear problems that show up in the field trace back to a handful of installation mistakes, most of which are genuinely easy to avoid once you know to look for them.

Skipping the dry-fit step. It’s tempting to go straight to bolting gear down, especially on a part that looks like an obvious, simple fit — but a proper dry-fit (see Day 5) is where most fitting problems, from hole misalignment to unexpected fuselage interference, actually get caught, before they’re locked in place with tightened fasteners.

Over-tightening fasteners “to be safe.” Covered in detail in Day 17, but worth repeating here because it’s genuinely one of the most common mistakes — tighter is not automatically safer with carbon fibre mounting points, and over-torquing is a real, common cause of cracked mounting plates at the point of installation rather than developing later from flight loads.

Ignoring axle alignment. A gear that’s correctly mounted but with wheels that toe in or out even slightly will cause take-off tracking problems that get wrongly diagnosed as a rudder or crosswind issue — the alignment check in Day 5 takes thirty seconds and prevents a genuinely common source of ground-handling frustration.

Fitting wheel pants before finalising gear and wheel position. Covered in Day 6, but worth flagging again as an installation-order mistake specifically — pants fitted first, then adjusted around, cause more rework than pants fitted last, around a confirmed gear and wheel position.

Not test-flexing before the first flight. The simple hand-push test from Day 5 catches a surprising number of installation problems — a loose mount, an unexpected creak, a leg that flexes unevenly — while you’re still safely on the bench rather than discovering it on a landing.

Most of these mistakes share a common thread: they’re all avoided simply by not rushing the installation, and by checking each step properly before moving to the next one rather than assuming a “should be fine” fit is a “confirmed fine” fit.

Our Carbon Undercarriage suitable for Acrowot XL is a good reference point if you’re shopping around.

Size and dimension charts look simple, but a surprising number of fitting problems trace back to a chart being read slightly wrong rather than the part itself being incorrect.

Know which dimension is which before you measure. Leg width (the flat dimension across the gear), mounting hole spacing (centre-to-centre distance between bolt holes), and axle diameter are three genuinely different measurements that are easy to confuse if a chart isn’t labelled clearly — always measure your own model against the chart’s stated reference points, not just against a general size description.

Check units carefully, especially with parts sourced internationally. Metric and imperial measurements mixed on the same chart, or a chart using a different convention than you’re used to, is a common source of small but real fitting errors — a millimetre-to-inch mix-up on axle diameter, for instance, is a classic and entirely avoidable mistake.

“Compatible with” claims should be checked against your specific model, not just its general class. Two models nominally in the same size bracket can have genuinely different mounting layouts even from the same manufacturer’s range — a chart listing broad compatibility is a helpful starting point, not a guarantee that skips the need to check your own model’s specific dimensions.

When measuring your own model for comparison, measure the actual mounting points, not the fuselage’s outer dimensions. It sounds obvious written down, but it’s an easy mistake to make when working quickly — the number that matters is where the bolts actually go, not how wide the fuselage looks from outside.

If a chart’s dimensions and your own measurements don’t quite agree, trust your own measurements and get in touch before ordering — it’s far easier to double-check a measurement or ask a question up front than to deal with a return because a chart was read slightly wrong.

You can browse our 20-35cc Carbon Fibre Undercarriage for Petrol / Gas / Nitro models. to see this in practice.

Most modern carbon fibre landing gear is designed for bolt-on fitting, but epoxy bonding still comes up, particularly on scratch-builds or older-style airframes, and it’s worth understanding when each is appropriate.

Bolt-on is the standard for good reason. It’s inspectable (you can remove the gear and check both the leg and the mounting area independently), replaceable without damaging the airframe, and it distributes load through a small number of well-defined points that can be individually torqued and checked (see Day 17). For the vast majority of models, if the gear and airframe are designed for bolt-on mounting, there’s little reason to deviate from it.

Epoxy bonding has a place, but it’s a less forgiving choice. It’s occasionally used where an airframe genuinely doesn’t have a practical bolt-on mounting point, or as a supplementary reinforcement alongside bolts rather than as the sole fixing method. The major drawback is that a bonded joint can’t be inspected the way a bolted one can — any developing weakness in the bond line is essentially invisible until it fails.

If you do need to bond gear in, surface preparation is everything. Carbon fibre needs to be properly abraded and cleaned (not just wiped) for a structural epoxy bond to have any chance of matching the strength of a well-executed bolted joint, and a two-part structural epoxy rated for the loads involved is essential — general-purpose hobby epoxy is not the right product for a load-bearing landing gear bond.

When genuinely unsure which method your specific gear and airframe combination calls for, bolt-on is almost always the safer default if the airframe can be adapted to accept it — the inspectability and replaceability advantages are significant enough that it’s worth some extra effort to achieve a proper bolted mounting rather than defaulting to bonding for convenience.

Our Carbon Fibre undercarriage for 50e and 50 size nitro is a good illustration of the kind of fit and finish to look for.

The size range across petrol and glow aerobatic models is wide, and it’s worth understanding roughly how the classes relate to each other if you’re moving up (or down) in scale.

30-size to 50cc class covers a lot of popular sport and lighter scale aerobatic models — generally lighter, more portable, and typically the entry point for pilots moving from trainer-style models into dedicated aerobatic or 3D types. Gear, wheels, and general hardware at this end of the range are correspondingly lighter-duty, sized for the lower weights and loads involved.

80cc to 100cc class represents a genuine step up in both scale presence and structural demands — models in this range are often serious club-level or entry competition aerobatic machines, and landing gear, fasteners, and fuel system components all need to be specified accordingly rather than simply scaled up casually from smaller-class parts.

150cc and above is squarely the large-scale end, where models start to genuinely resemble their full-scale counterparts in size and presence, and where every component — gear, fuel system, ignition — needs to be selected with real margin rather than minimum-spec, given both the values involved and the consequences of a failure at this scale.

Moving up in class isn’t just “buy bigger everything.” Weight, structural loads, vibration characteristics, and fuel system demands all scale in ways that aren’t perfectly linear, which is part of why manufacturer size brackets (see Day 1) exist rather than a single universal formula — a component correctly sized for 50cc use doesn’t necessarily scale proportionally and safely to 100cc just because the numbers look related.

If you’re moving up a size class for the first time, it’s worth treating it as a genuinely new specification exercise for gear, fuel system, and hardware — rather than assuming your existing knowledge and component choices simply scale up alongside the model.

Take a look at our EXTRA 300 26cc – 35cc Carbon Fibre undercarriage for a solid example of correctly sized gear.

A well-stocked field box saves more flying sessions than almost any other single habit, and it doesn’t need to be expensive or complicated to be genuinely useful.

Fasteners first. A small assortment of the bolt sizes your models actually use, plus a spare tube of thread-lock, covers the single most common field fix — a loosened gear, cowl, or engine mount bolt discovered during a pre-flight check (see Day 17).

A spare glow plug or spark plug, matched to whatever engines you’re actually running that day, is cheap insurance against a session-ending failure that would otherwise be a simple two-minute swap.

Basic ignition spares if you’re running petrol — a spare kill switch lead and, if you’ve got the budget for it, a spare ignition module for your most-used engine, since ignition failures tend to be sudden and total rather than giving you warning.

A spare prop or two in your common sizes, since a strike serious enough to end a flying session but not serious enough to be an obvious safety issue is a genuinely common occurrence, and there’s little worse than driving home early over a five-minute prop swap you couldn’t make because you didn’t have a spare.

Basic landing gear spares are worth considering if you fly regularly from grass (see Day 9) — even just spare mounting bolts and a spare wheel or two, since these are exactly the components taking the most repeated, unpredictable load on a typical flying day.

A simple field checklist, even a basic one, catches more issues before they become spares-box problems than the spares box itself ever will — the two work best together, not as alternatives to each other.

None of this needs to be elaborate — a genuinely useful field spares kit is more about consistency (always having the basics, every session) than about having every conceivable spare part on hand.

For a real-world example, have a look at our Protective RC Wing Bag 50-70cc size.

Fuel systems don’t get the glamour of engines or gear, but a poorly specified or poorly plumbed tank causes more mysterious “engine problems” than almost any other single component.

Size for your typical flight duration, with margin. Running a tank close to empty regularly isn’t just inconvenient — it increases the chance of uneven fuel pickup and air getting into the line as the fuel level drops and sloshes with manoeuvres, which shows up as intermittent lean running or cutting out, often blamed on the engine rather than the fuel system.

Placement affects feed consistency through the flight envelope. A tank mounted too far from the engine’s ideal fuel level, or positioned so that aerobatic manoeuvres regularly uncover the pickup, will cause exactly the kind of intermittent fuel starvation that’s maddening to diagnose in the field. Following the airframe designer’s recommended tank position (rather than fitting the largest tank that physically squeezes in) avoids most of this entirely.

Clunk placement and free movement matter as much as tank size. A clunk that’s snagged, kinked, or restricted in its movement inside the tank defeats the purpose of having one at all — it’s worth a visual check (tank empty, clunk moving freely through its full range) whenever you’re setting up a new tank or troubleshooting inconsistent running.

Fuel line condition degrades gradually and easily gets overlooked. Silicone fuel line can harden and crack over time, particularly with petrol rather than glow fuel, and a line that looks fine but has lost flexibility is a common, easily-missed cause of intermittent air leaks into the fuel system.

A full fuel system check belongs in the same pre-season routine as gear and fasteners (see Days 14, 15, and 17) — it’s an unglamorous job, but fuel system issues are among the most common causes of in-flight engine problems that have nothing to do with the engine itself.

Our Petrol conversion fuel tank bung and fittings is a good reference point if you’re shopping around.

Propeller selection is its own deep rabbit hole, but a few fundamentals apply broadly across most gas and electric sport and scale setups.

Diameter and pitch are doing different jobs. Diameter is broadly related to how much air the prop can move (and therefore how much static thrust it can generate), while pitch relates to how far the prop would theoretically travel through the air in one revolution, which affects top speed and how the engine or motor loads up at different RPM. Manufacturer-recommended combinations for a given engine or motor are a sensible starting point rather than something to second-guess without good reason.

Gas engines generally want a specific pitch range for the engine to run happily, and going too aggressive on pitch can load the engine down below its efficient RPM range, hurting both performance and engine longevity — this is one area where following the engine manufacturer’s recommended prop range genuinely matters, rather than being an overly cautious suggestion.

Electric setups have more flexibility but more room to get it wrong, since motor, ESC, battery, and prop all need to work together within safe current draw limits — a prop that’s fine on one motor/battery combination can be genuinely unsafe (overheating the motor or ESC) on a different combination, even at the same nominal size.

Balance and true running matter as much as size selection. An out-of-balance or slightly warped prop introduces vibration that affects everything downstream — engine mounts, fasteners (see Day 17), even radio gear reliability over time — regardless of how correctly sized the prop otherwise is.

When in doubt, start conservative and work up, particularly on a new engine or motor combination you haven’t run before — it’s easier to notice a prop that’s slightly too small than to recover from over-stressing a new power system with too aggressive a first choice.

You can browse our Carbon Fiber Propeller For RC Fixed Wing Airplane 19×8 19×10 22×10 23×8 23×10 24×8 24×10 Propeller to see this in practice.

Spinners are often treated as a purely cosmetic finishing touch, but a poorly fitted or unbalanced one can genuinely affect how a model runs.

Balance matters more than most flyers expect. An out-of-balance spinner, spinning at engine RPM right at the front of the model, introduces a genuine vibration source — one that’s easy to blame on the engine or prop when the spinner itself is the actual culprit. A quick static balance check before fitting (balancing the spinner alone on a suitable fixture, checking for a consistent rest position) is worth the couple of minutes it takes.

Backplate fit affects prop and spinner alignment together. A spinner backplate that isn’t sitting flush and square to the prop driver introduces run-out that no amount of careful prop balancing alone will fix — it’s worth checking backplate seating specifically, not just assuming a snug fit means a square fit.

Match spinner diameter to cowl, not just to prop size. It’s a surprisingly common mismatch — a spinner sized correctly for the propeller but slightly wrong for the cowl opening either leaves an unsightly gap or requires more cowl trimming than expected. Checking both dimensions against the spinner’s spec before ordering saves a return or a rework.

Carbon fibre and composite spinners generally need less balancing correction than some alternatives, thanks to more consistent manufacturing tolerances, but “generally less” isn’t “never” — it’s still worth a balance check rather than assuming a premium material guarantees a perfectly balanced part straight from the packet.

A well-fitted, properly balanced spinner is one of the cheaper, quicker upgrades available for both looks and smoothness — it’s just worth doing the fitting properly rather than treating it as a five-minute bolt-on job.

Our 1.75″/44.45mm Drilled Alu Prop Spinner for DLE30/55 MLD35/70 DA50 EVO54 Engine is a good illustration of the kind of fit and finish to look for.