FlyBoy1960

On a Rotax 912 (twin Bing carbs), that “balance pipe” is basically a plenum-to-plenum equaliser between the two intake sides. It primarily: Equalises manifold pressure between the two sides (helps share load between carb/intake pairs) Damps pulsations (intake pulses are strong on a 4-stroke, especially at low RPM) Can slightly influence idle/off-idle smoothness and how stable the carbs feel during synchronisation What changes if you go from ~8 mm ID to 20 mm ID? Area matters a lot. 8 mm ID area ≈ π·4² ≈ 50 mm² 20 mm ID area ≈ π·10² ≈ 314 mm² So you’d be increasing cross-section by about 6.3×. That means the balance connection stops being a “small equaliser” and starts behaving much more like a common manifold link between the two sides. Likely effects you’d notice (if any) 1) Idle and low-RPM smoothness could change (sometimes better, sometimes worse). A larger tube usually reduces pressure difference between sides more quickly and can dampen pulses more. That can make idle feel smoother if you currently have unevenness between sides. But… if you go too large, you can also create a situation where: one side’s intake pulses strongly influence the other side, mixture distribution and response around idle/off-idle can become less “crisp” or occasionally hunt/surge depending on how the rest of the intake is configured. 2) Carb synchronisation behaviour can change. With a big balance pipe, the two sides are already heavily “averaged together”, so: it may become harder to detect a small imbalance using manifold pressure/CarbMate-type methods (because the balance pipe masks differences), you might end up with an engine that seems balanced by reading, but still has subtle cylinder-to-cylinder inequality. 3) Midrange and high-RPM power: usually little to no improvement. At higher RPM and larger throttle openings, the balance pipe generally has minimal benefit because both sides are already flowing heavily and the pressure differences are smaller relative to overall airflow. A larger balance pipe typically won’t give you more power. 4) Risk of unintended side effects goes up. Going to 20 mm ID is a big jump. Depending on your exact intake layout, you could introduce: odd transients (tip-in / tip-out throttle response changes), cross-feeding effects if one carb is slightly richer/leaner than the other, potentially more noticeable issues if a carb/diaphragm/jetting problem exists (the big pipe can “share” the problem). The practical/engineering takeaway A balance pipe is usually sized to equalise slowly enough to damp differences but not so large that the two sides become one big coupled system. Jumping from 8 mm to 20 mm is not a small tuning tweak; it’s a redesign of the coupling strength. What I’d recommend instead of going straight to 20 mm If your goal is smoother idle / better balance, you’ll usually get more reliable results by: doing a proper carb sync (idle stop + cable sync at ~3500–4000 rpm), checking diaphragms, intake sockets, clamps, balance tube condition, and any vacuum ports/caps for leaks, confirming float levels and correct Rotax compliance items (many “roughness” complaints are float/diaphragm/leak/sync related rather than balance tube size). If you really want to experiment, a safer approach is incremental (e.g., 10–12 mm ID) and verify with: EGT/CHT consistency (if you have it), idle stability, plug colour / fuel flow consistency, and repeatable run-up checks. One key caution Because this is an aircraft engine, changing intake hardware can have certification/maintenance and safety implications depending on your aircraft category (RA-Aus, experimental, certified installation, etc.). Even if it “runs”, it may not be a compliant modification.

Go out in a gyro, come home in a helicopter. Sounds like a normal day for some of these guys.😇

it's not about what everyone else loves it is what you will be happiest owning and flying. I thought I would use AI to get some more information. There were only 66 Skyfox CA25N Gazelles ever made, 61 were sold in Australia and the other 5 overseas. This does NOT include any that were made after 1996 which was apparently when the factory was closed and reopened under new ownership. The new owners apparently built 3 with 1 being sold and the other 2 being used for parts because they could get more money for them than selling them new. most of this information came from Wikipedia and the Queensland air Museum according to Chat GPT. Interestingly they were about 3 times more X-Air aircraft sold in Australia, probably because they were cheaper and could be kit built ?

Keep it - you won't have as much fun in anything else. 😀

YEEP.. Get the chinese stuff, no problems. I would also recommend you use a really cheap Kmart oil in the engine, or better yet get used oil because you know if you filter it it will be almost as good as new. Go budget all the way and on the day you need to use your radio for an emergency, no one will hear you, but that's okay. ⛔

if you look at his legs when he hit the result of stabiliser I'm surprised they were not both broken in half !

No from the old office to the new office

Nope.. A lot of the filing cabinets went to the tip in error when they moved between offices.

I have no evidence of anything but if they are requiring a BFR for a high-performance aircraft and another BFR for a thruster and another BFR for something else then this would tell me something is going on in the background that would have to be validated by.. If accident statistics that prove if somebody had a BFR in a thruster and then immediately crashed there plastic fantastic then it would indicate a problem. If accidents statistics prove they just had their BFR in a plastic fantastic and then crashed there thruster then it would indicate a problem. if this could be proven then there may be a case that you need a BFR in each different category of aircraft as proven by accident statistics. If it can't be proven by accident statistics then it could only be instructors are after more income by trying to provide a BFR in each qualifying category. personally, I can't see this being truthful at all because there has never been a whisper of somebody rolling up a thruster the day after they got their BFR in the plastic fantastic. If it were truthful it would have been publicised well before now but who knows what is going on in the background with the RA-Aus

I don't know anything at all, I just chose the icon caution because if this statement is correct it is simply a money grab by struggling instructors who are sourcing to get more income doing endorsements. That should be a caution or a red flag to anyone

It’s a small speaker/buzzer that: Is fairly loud (90 dB at 10 cm) Works best around 430 Hz Should normally be powered at 0.2W, but can handle 0.4W briefly Has an impedance of 45 ohms

Gee, that time goes quickly. RIP

I am lost Skippy, i also have IFR, Multi engine, turbine etc ratings on 'real' planes and others as well. But my experience is that going through the commercial drone system in 2025 was significantly more intensive than any of the general aviation ratings that I have. That is my opinion based on my experience and nothing else.

I must say that the training for a CASA approved, commercial drone pilot with RePL and REOC is to a much higher KNOWLEDGE level than it is for a recreational pilot by a really large margin. Not meaning to offend anybody but those with the qualifications in both commercial ops and RA-Aus aircraft will know exactly what I mean. The knowledge required for commercial drone exceeds what I did for IFR and instrument ratings in general aviation. T510 would agree with this statement, I am sure

the flywheels would be going in different directions ?