Gross Weight Increase For Sonex/Waiex

[markschaible]

But- what about us?

Kai, I am always happy to speak directly with government certification authorities on-behalf of our customers to support our current specifications and help with build approvals when required. As has always been our policy, please have your CAA representative contact us directly and we'll do our best to help. In the coming days you'll have revised Flight Manuals and -B01 drawings to support your communication with authorities as well. Make sure you are subscribed to the Sonex Tech Updates mailing list for automatic notification of these revisions.

There is no question that the vast majority of our customer base is in the United States and will continue to be so. MOSAIC certainly was a catalyst for this project as we were convinced that we could not demonstrate stall speeds within current Sport Pilot limitations. Happily, our fuselage design attributes proved their value once again in keeping stall within current limits. The MOSAIC or "Sport Pilot 2.0" proposed rule has no gross weight limitation, and stall limitation in the proposed rule has been increased to 54 knots Vs1 (62 mph) and is likely to be increased further in the final rule. Given that, don't you think we would expand gross weight beyond 1220 lbs. if we thought it was feasible? We arrived at 1220 lbs. for reasons including acceptable structural safety margins and acceptable climb performance. We consider this a hard limit and we absolutely do not want customers to take further liberties with it.

Everyone also has to keep in mind that, although I served as General Manager at Sonex for many years, these kinds of product development decisions were not mine to make until I became the owner of the operation in 2022. You will see more announcements from us in the near future as we work to continually improve our products and processes. As we've always said: "We reserve the right to improve our products at any time!"

You will NOT see further expansions to Sonex and Waiex max. gross weight unless they are accompanied by significant changes to the aircraft structure, which is not in our current product development planning. The Sonex HIghwing, for example, is designed to accommodate a 1500 lb. max gross weight in Utility Category. That kind of gross weight capability drives structural weight, however, and the Highwing will weigh 800 lbs. or more empty.

I must reiterate that the Sonex & Waiex gross weight change does NOT take into consideration wing tanks or other modifications. Wing tanks change the bending moment load on the wings, and as I stated previously, that can have negative impacts at high speeds in gust loading conditions. I'm also aware that there are aftermarket wing tip extensions for Sonex and Waiex that have received some positive flight reviews, however, those are absolutely NOT approved by Sonex as any increase in wing span increases the bending moment load on the wing structure, even though it reduces wing loading. Modifications such as wing tanks and wing tip extensions basically require that all of our engineering and testing be completely re-evaluated. These considerations are not part of the aircraft's design.

There was a question about the landing gear capacity: We consider the Xenos max. gross weight to be the absolute limit of the current landing gear.

Some have asked whether increases in max. gross weight are coming for the Onex and Xenos, and the answer is no:

Onex: You have an aircraft that solidly weighs approximately 600 to 620 lbs. with paint and has only one seat. With full fuel and full baggage the Onex can accommodate a pilot up-to 240 lbs. The aircraft has a narrower chord than the Sonex and it would be very difficult to make the aircraft much heavier while staying within the CG range. Also, the landing gear has not been designed for gross weights above 950 lbs.

Xenos: As-discussed, the Xenos landing gear (same as the Sonex and Waiex) cannot accommodate a higher gross weight and further, we consider the Xenos max. gross weight to be the safe limit of the wing structure with appropriate safety margins per our static load testing.

[Skippydiesel]

Mark,

Thank you for your fulsome reply and once again for the 31.75 kg Max TO increase, which will make a significant difference to the utility of my Legacy.

The new Highwing should fit nicely into Recreational Aviation Australia's (RAA) latest weight increase (some details yet to be resolved). May I suggest that you consider offering fuel tank capacity options, with a view to greater duration for pilots who may need it, as part of the future kit.

[tice@qvation.com]

I'll say....Its how the airplane was designed. If people are unhappy with it, pick another airplane or design your own.

The airplane could probably safely take off with another 100 pounds. Would it be safe to fly? Probably not. Would it be safe to land. Probably not. Would it be stall/spin tolerant? Probably not. Would it be appropriate for intermediate pilots? Definitely not. There are plenty of advanced airplanes out there with higher wing loading that fill a different mission. The Sonex fills its mission just fine as it is.

Sonex has always stood behind their product and offered great customer support. The airplane wasn't designed to be a heavy hauler. Its a simple airplane for two fit size people to fly locally or to the $100 hamburger.

Just pick a different one.

Well said Scott! Can we now end this idiotic discussion. Thanks