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There is already a raft of exemptions from CASR, one set is the whole basis for RAA possible and is an exemption from pilot licensing requirements and airworthiness standards.

Much the same as amateur built experimental works I would imagine. Have you noticed all the aircraft getting around with EXPERIMENTAL written on them? RV-6, 7, 9, 10, Jabiru etc.

I posted a link to the actual regulation, "up to date as of 6/08/2023" (US date). How new do you want? I suspect the AC hasn't changed since 1982 because the regulation hasn't significantly changed. Whose obligations? Even in Australia it's possible to be responsible for your own actions, not everything has to be administered by an organization.

I think you're missing the point of the US FAA part 103. Part 103 is for ultralights that are slow enough and light enough that they don't require an organization to administer. The pilot is 100% responsible for their own safety. Part 103 ultralights don't require airworthiness certification standards cannot have an airworthiness certificate pilots are not required to have any training ultralights are not required to be registered with any organization Eligibility requirements are: maximum empty weight 254 pounds 5 gallons maximum fuel capacity maximum 1 seat maximum speed 55 knots in level flight at full power maximum stall speed 24 knots The only thing to administer is eligibility, and the pilot is required to provide evidence to the FAA if required. The FAA are helpful enough to provide graphs etc. which they will accept as satisfactory evidence if the ultralight fits those parameters. The AC is an Advisory Circular, it is only advisory. Basically the section you are focusing on says we know people will try to bend the rules, and if you're going to bullshit us about the magical capabilities of your ultralight that doesn't fit the parameters we provided, you need to find 3 qualified people willing to sign their names to the bullshit. The FAA obviously hope that this is not required, but is realistic enough to document it. A technical committee doesn't need to do any complex evaluation, just answer the questions "Is the maximum speed at full power less than 55 knots?" and "Is the stall speed less than 24 knots?" You want to put balloon tyres on it? Put it on the scales, if it's less than 254 lb and the stall speed calculation works, go for your life. That's all there is to it.

Speed brakes was an example in the FAA AC. FAR 103 is limited to aircraft that cannot exceed 55 knots at full power in level flight. Automatic speed brakes was given as an example of an artificial way to meet that limitation. It's not something they are recommending - they are intentionally making it more difficult to meet the regulations artificially than simply by building a low power, high drag airframe. No, part 23 does not apply. From the AC: "The FARs regarding aircraft certification, pilot certification and aircraft registration are not applicable" It's worth reading the actual regulation - it's only 2 pages. https://www.ecfr.gov/current/title-14/chapter-I/subchapter-F/part-103

The first part is just definitions. You need to read further to find when a technical standards committee would be required. E.g. an equivalent in Australian regulations, certain modifications to aircraft need to be certified by an engineer. That doesn't mean that Australian aircraft cannot operate if there are no engineers that can do that job - it just means you can't make the modifications. It's only a problem in the circumstances when they are actually required. And you only have to form an organization if it says an organization is required. If it says 3 qualified people, you just need the 3 qualified people.

You don't seem to have read the FAR 103 information. The FAA can inspect an ultralight to see whether it meets the standard It is the responsibility of the pilot or operator to provide evidence that it does The FAA even provide you with the information to provide satisfactory evidence: "The use of the graphs provided in Appendixes 1 and 2 will be acceptable for determination of the maximum level flight speed and power off stall speed if your ultralight has no special limitations to maximum speed or power and no special high lift devices" The Technical Standards Committee is only required if you have special limitations or high lift devices e.g. automatically deployed speed brakes to meet the requirements. I guess to stop people getting too clever with workarounds.

VH Experimental seems to manage. All those RVs etc. getting around with EXPERIMENTAL on the side are not flying under a SAO. CASA does not set airworthiness standards for experimental aircraft. SAAA don't sent airworthiness standards either. SAAA are not a SAO, and builders/owners are not required to be a member of SAAA. All liability is assumed by the builder and/or owner and/or pilot. I would expect that RAA operates in a similar way for their amateur built aircraft - it seems unwise if they assume any more liability then CASA does for VH. I doubt there have been any court case where CASA have been sued for failing to set rules for Experimental - I wouldn't expect any different for e.g. 95.10.

Screw that. If you want to move the discussion to another thread that's fine, but make it accessible.

I'm not allowed to post to tat thread for some reason

CAO 95.10 seems to still exist. What does FAR 103 provide that is not available under 95.10?

Very convenient, when you don't have an answer to a question that must have an answer if you are correct. I have been reading what other people have been saying, and I know who knows what they are talking about and who does not.

The C172 has a forward limit of 35 inches aft of datum at <1950lb varying to 41 inches aft at 2550lb, and an aft limit of 47.3 inches aft of datum. You can absolutely point to tangible locations between these limits. If you could measure from the datum, draw lines and balance it on your thumbs like a model aircraft between the lines you could say it is within the CG limits. There are 2 graphical representations of the CG limits. One is, as you say, the sum of the moments. This is a looks like a chart skewed sideways. The other is the actual CG. That is a much squarer chart, sometimes e.g. C172, PA28 with corners cut off. You get that by dividing the sum of the moments by the weight. It gives you a number that you can actually measure from the datum and point to on the aircraft.

djpacro has shown why I phrased it carefully. The C210 example is still CG, not landing weight (if it is weight, can you tell me the number?) The zero fuel weight in the Cherokee 6 is a different (more common) scenario.

Well there you go... 38 kg of fuel would take a while to burn off in a 152. Any examples that were designed that way, i.e. not via STC, Experimental etc?

You could hang a 1 tonne weight in the CG range and balance would be correct (although the permissible range often reduces with weight so there might not be a usable CG range...) But the zero datum point is just a point chosen as the point to do your measurements from. Usually, it is something easily measurable like the firewall etc. If you put it at the CG you have to work with positive and negative numbers. If you choose a point further forward, all your numbers are positive.

I agree - the sample for the PA28 looks the same. Partly because of the shape of the envelope. The forward limit reduces with increasing weight, and the CG moves forward as fuel is used. The forward limit moves forward faster than the actual CG as fuel weight decreases.

We know you were referring to weight. But I haven't encountered small aircraft where the maximum landing weight is less than the maximum takeoff weight. Did you have specific examples in mind? The C210 example is referring to CG. I could not find anything about maximum landing weight.

It is fairly common. C210 obviously based on this example. It's well known for Bonanzas. Probably most aircraft where the CG can approach the limits. I'm curious, I will have to work a sample for a C172 and PA28 and see whether you can load it so it goes out of balance as you use fuel.

Turboplanner wrote: Facthunter and I replied: Turboplanner replied: Turboplanner's original post was referring to weight, i.e. you may have to burn fuel before landing. But the C210 POH is referring to CG.

The Cessna 210 POH is referring to calculating the CG. Maintaining CG within limits as fuel is used is important for every aircraft, not just cross country. It is not a maximum landing weight and doesn't require you to use up fuel before landing.

C152 and Jabiru are both 2 seaters where you may not be able to carry 2 people and full tanks. It's often said any aircraft where you can fill the seats and the fuel tanks should have bigger fuel tanks. What is the smallest aircraft where maximum landing weight is less than maximum takeoff weight?

"Whatever it takes" isn't much help if you don't know what it takes. What it takes is Vy. That's why the number is in the book. Vx, Vy, best glide - they are documented for a reason.

We're not talking about standard everyday practice. We're talking about what you do when...

Sure - in normal operations a higher speed "cruise climb" is fine. But if you're not climbing, Vy is the speed you need. Speed above Vy is not your friend (unless you are overloaded, when a few knots might be helpful due to induced drag equations). Vy might be the difference between climbing away and crashing. ATEC list 110 km/h i.e 60 knots as "optimum" speed which I assume is Vy. About what I would expect. If you NEED the performance, you NEED to fly the speeds.