don´t take LSA approval as prove the UL version is OK to fly on 600kg. If you build an aicraft to MTOW of 600kg the structure will be too heavy for UL category. So the manufacturer has choice – delivery heavy weight UL or have two versions with some structure modification. You need to find out before a simple statement “it´s ok to fly on 598 kgs”. It might be ok technically in some cases, but definitely not in all. Not speaking about legal aspects.
If you build an aicraft to MTOW of 600kg the structure will be too heavy for UL category.
Excuse my scepticism here. Any illustration or example? It seems unlikely to me that, for just one example, the FK-9 would be built on a different frame to qualify as an LSA, the cost of development would be heavy. At most, some extra stiffeners/gussets might be added, or sturdier landing gear.
Also, the max G-load is an important figure here. Ultralight requirements in most European countries are +4/-2G but I do not know LSA requirements, neither FAA nor EASA.
to Jan: I understand your skepticism….the differences are not huge and some of manufactures opted to have a heavy UL instead of dealing with small differences for sure. Some not – check http://www.evektoraircraft.com/ for SportStar and Eurostar – look at the wind span and other parameters. Both aircraft looked alike but there is airframe differencies underneath the skin and not only underneath the skin.
If you build an aicraft to MTOW of 600kg the structure will be too heavy for UL category
This isn’t true at all. Sonex Aircraft designed the Sonex some 15 years ago particularly for the European ultralight, while retaining larger MTOW and heavier engines and aerobatic capabilities (+6/-3 g) for experimental and (E)-LSA.
All the aircraft I listed up are the exact same aircraft for LSA and ultralight as the factory pages confirm. That’s why I listed them, and there are most probably many more.
Structural strength is not the problem. The “problem” is stall speed at MTOW. Ultralights are restricted at max 64 km/h (34.5 knots), while US LSA are restricted at 45 knots (83 km/h). 64 km/h at 450 kg with flaps is more restrictive than 83 km/h at 600 kg clean. At the same time US-LSA is restricted to max 120 knots (222 km/h) level speed at sea level, while European ultralights have no speed limit. An airplane with a Vne of 300 km/h at 450 kg and a cruise speed of 270 km/h, certainly has no structural problems with 220 km/h at 600 kg, but the stall speed at 600 kg will be considerably higher than 64 km/h.
An airplane with a Vne of 300 km/h at 450 kg and a cruise speed of 270 km/h, certainly has no structural problems with 220 km/h at 600 kg
I am not sure that follows at all, automatically.
There is a huge difference between 300 and 220, in terms of possible flutter and also control surface forces remaining monotonic, progressive, etc.
I am not sure that follows at all, automatically.
An increase in speed of 36% requires much more added structural rigidity than an increase of mass of 33% (and it certainly follows automatically). It basically means an ultralight with MTOW 450 kg and Vne of 300 km/h are more stressed structurally than a US LSA at MTOW 600 kg. I really don’t think it matters either way though. These modern carbon fiber shell structures are way stronger than they “need” to be anyway. Even a well designed aluminium airframe has no problem with this. Cloth and tubing on the other hand?
@Michal: thanks for patient and positive discussion, this is the way a forum should work!
You are right, Evektor are doing things properly; but they must be the exception.
NB I came across the ELSA G figures: the positive was 3,8 , slightly less than the +4 for an ultralight – bringing the 600 kg closer to the 450, as I suspected, but by only 5%. On the negative side the ELSA requirement is -1,5, that is a 25% decrease from the UL’s -2.
the point is – and where this discussion started – the nonsense of having several categories. UL is Europe was born as tube and fabric home builds. They have done a long way since that getting pretty close to certified aircraft and quite often exceeded this well established category. For future there is no place for several categories in the same air – UL, LSA, permit to fly, experimental, TMG, SEP. The way I have drafted 10+ years ago slightly modified:
simple home builds – something where the original UL started, tube and fabric, weight limit approx < 500 kg, STRICT speed limitation (both stall and cruise/never exceed). This category should have very limited oversight to really allow home builders. Maybe limited to uncontrolled airspace, light pilot license requirements. why to ask these guys to have knowledge of VOR navigation.
high techULs/LSAs/small SEPs/TMGs – something up to 600-750 kg or even 1000kg or 2000kg if we are bold, not a strict limit on speed, allowing faster machines, PPL or PPLlike – with high performace or other endorsments. Currently if you want to fly EV-97 or C-42 you need UL license. Cessna 152 – you need PPL. Dimona motor glider – you need glider/TMG (unless you have TMG in your PPL – 6 guys in whole Europe). All these machines are travelling 90-100 kts, doing the same job – flying 1 or two guys around not too far but pilot/maintenance/modification regulations are absolutely different. Typical UL requirements are sometimes not enough here (flutter, pilot trained in crossing controlled airspace to name few) but strict limitation of part 23 are not definitely adequate. Why not to allow simple installations of XXX other way than minor/major modification by EASA approved organization/EASA. Is replacing a propeller with another certified propeller on my own aircraft flown just by me something I need to stop by in Koeln for extensive safety evaluation?
pilot qualification –
have UL like license usable for tube/fabric category. I am glad EASA quietly removed LAPL basic (even in the initial CRD they insisted on this nonsense) but LAPL is still somehow questinable. Why to keep LAPL and UL as two different worlds?
have PPL for all above. We can discuss whether current form is suitable for leisure pilots or as stage 1 of ATPL training but this is a different question.
bottom line – simply use the good points from UL and part 23 regulations aircraft to have an optimum. But the current strict position of UL world (don´t put more regulation into our playground) and EASA world (we need to ensure safety and we know how) are simply wrong. And if you ask me – I guess it needs to start from scratch from black sheet of paper. There is no way in simplifying CS-23 (do you remember JAR VLA?) or making UL rules strict. I just wonder what FAA is doing on current rewriting of part 23 – hoping some clever EASA guys are taking parts in meetings regularly.
Just food for thought (and because time is limited right now): Defining the mass as a distinction parameter is nonsense. Has been and will be.
And: Building an Airplane for 472,5 kg MTOM that can carry 600 within its envelope is nothing just bad engineering. Commercial aspects aside. But then again, ULM / US-LSA “Certification” is not that troublesome.
Defining the mass as a distinction parameter is nonsense.
What then would be a less nonsensical parameter? Why should a B747 not be registered and flown as an ultralight? What does the “light” in ultralight stand for?
For myself I can see some sense in it: the idea behind most countries’ UL ruling is to limit the requirements on the pilot but to counterbalance this increase in risk by a reduction of the possible damage, by limiting the kinetic energy by limiting mass. Unfortunately they forgot to limit speed – I quite agree with Michal’s remark, here and elsewhere. A nice side-effect (from a regulator’s point of view) is that, if one manages to kill someone with such a craft, it will most likely be the person(s) in said craft, rather than some innocent soul outside; making careful maintenance and safe piloting a matter of self-preservation and that is a pretty strong tendency in most humans.
And yes, Michal, we have too many types of license today, and too many overlaps. I agree that the ultralight status should be more limited than it is today in most countries, by having a max speed limit and by excluding “complex” features such as variable pitch props and retractable gear. OTOH my idea would be rather to extend the LSA to the current spam-can category, and to require the proper PPL only for high-end machines as flown by most people round here: complex machines and/or multi-engine. This would also keep in place the current distinction between the national UL-license versus the EASA LSA and PPL licenses.
