Head in the clouds

Mechanical instruments are generally most accurate at the mid-range of their scale so an instrument like this would have been fitted to an aircraft with a 'normal' climb rate of around 1500-2000ft/min which pretty much dis-counts it from having been from any fighter. Also - a black face and white luminous painted scale and pointers was standard for any aircraft which might have to fly at night occasionally without instrument lightning. I think the white face and black scale was generally used where night operations were normally conducted with red cockpit and/or instrument lighting. Without serial number history and documentation I think it would be very difficult to determine exactly which aircraft this would have come from, or probably even which type, but it might have been one of the civilian types that were also used by the AM, perhaps something along the lines of the Airspeed Oxford, though Googling images of the Oxford's panel show all the instrument faces to be black. Nice collectable nonetheless, does it still work? And - perhaps you forgot to attach the email from the museum?

12th February to 6th March 2016. How time flies when you're having fun. Another three and a half weeks since the last report but lots of fabricating has been done as well as planning and prep work to get the next materials order worked out, a bit more of the CAD and design work and all that fitted around my real job which is starting to get busier now as the construction industry year gets up steam again. I usually try and make log reports when milestones are reached, in other words when the next part of the build is completed but at the moment I've been working on several things at once so I have quite a number of things that are partially completed. I finished welding the joystick assembly but haven't taken a photo so I'll show that next time. The biggest priority I had was to get the next lot of materials ordered so that took up a fair while just mentally going over all the next stages in the hope of not forgetting to order something or other because the freight costs add 20% or so to every order and they also have minimum order amounts, so you can't just order a single piece of tube or plate that you missed ... anyway I got the order finalised and sent off - another $1000 or so of materials - and as far as I can tell I only forgot a couple of items which can be ordered next time when I get the materials for the wings. I fitted the Rotax ring mount to the engine and roughed out the CAD model of the engine mount, and produced the machining drawing for the rubber vibration isolation carriers. I had them machined as they are a bit heavy for my small lathe. While I was at it I modelled the tailwheel assembly as well. While I was waiting on the freight I set up the HS and VS jigs on the project bench, cut all the tubing, descaled it in the lathe, notched the ends, painted it and welded up as much of it as I could in the jigs. I was limited how far I could go by not having the ribs to install yet. I was able to make a preliminary fit-up of the ventral fin to the vertical fin and match them to the attachment points on the fuselage, adjust them accurately and then weld all in place. It all fits nicely and the two-piece rudder post is straight, which is pleasing, since it only takes one of the legs to be 1-2mm longer than the other to really throw the alignment askew. Next I set up the blocking for the tailwheel support assembly. It's an unconventional tailwheel setup because it will have to deal with rolling over some rough surfaces on occasions as well as being thumped down for landings in confined areas, so instead of the traditional leaf-spring design I have a strong trailing link supported by a reasonably long-travel strut above, which is buried in the aft fuselage structure and attaches near the HS attachment on a cross-member between the top longerons. The completed assembly is shown in the centre of the picture above. The tailwheel fork is a bit more complicated affair than usual too. It's quite a large tailwheel, the tyre is a 3.00x4 on a four inch rim, so it's 250mm/10" diameter and about 85mm/3.4" wide, consequently a sheetmetal wheel clevis large enough to carry it would be quite heavy, especially for the aft fuselage where we like things to be as light as possible. I found a very small tube bender that bends 3/8 tube as tight as 43mm/1.6" c/l radius. It's made of gravity die-cast aluminium and only intended for copper plumbing tube but I managed to make most of the bends in the CRMO tubing before I broke one of the handles, then grafted a stronger and longer handle on and kept going. Some of the bends can be seen on the extreme right side of the pic above. Once the new materials arrived I was able to mark out the guillotining of the thin 0.025"/0.6mm CRMO sheet for forming the ribs for the tailfeathers and have that cut up. Then bend the 5/16 CRMO tubing for the brake pedals, using the revitalised bender, also in the picture above. I deburred and descaled the guillotined rib sheetmetal and marked out the notches in the ends of them, cut them and painted them. Then it was time to re-visit the mini brake press I made a month or so ago. I had some off-cuts to use as practice pieces and found I needed more control of the blade to get both ends of the bends reliably at 90 degrees and also to keep the blade central to the V bed. Clamps, packers and spacers took care of that and it started to make accurate bends. The first part was to go through all of the rib blanks and make a 10 degree bend 3mm/1/8" in from the long edges. This is to protect the fabric from getting worn by the edge of the sheetmetal. Then the 90 degree bends have to be made very accurately because the rib must end up exactly the same width as the diameter of the tubing it will be welded to. The HS and VS ribs are parallel because the front and back tubes are both 7/8" diameter, and the elevator and rudder ribs taper from 7/8" to 3/8" at the trailing edge. Half a day's work and that job was done and the little brake press could be put away as I don't think I'll have a further need for it this project. I fitted and welded the ribs to the VS and they worked out well. I had to drill one rib to accommodate the 3/8" diameter diagonal brace which resolves the tailplane wire rigging loads, and I also added the internal ventral fin web members which prevent the fabric tension pulling the top and bottom chords (tubes) together. Last I started making up some of the endplate/clevis assemblies that attach to the inner ends of the HS to allow it to hinge up for trailering. Another 84 hours for the log, a total of 813 hours so far.

Welcome to the forum DZ. If you're looking for a very basic ultralight glider you'd do well to have a close look at the Sandlin Goat. Plans are available and cheap enough IIRC and their performance is surprisingly good for an open-air primary glider design. They're also well proven and cheap and simple enough for a first-timer to build. As far as licencing is concerned ... you don't need a 'licence' for a glider (or an ultralight come to that), instead you need a pilot certificate (PC) issued by the authority that controls the kind of aircraft you're flying. If you've been flying hanggliders presumably you already have a PC issued by the HGFA. Certainly you can build an amateur-built glider, or motorglider. You need to do a bit of reading to understand exactly what constitutes a glider and motorglider. Their design and operation is detailed in Civil Aviation Order (CAO) 95.4 A valuable first step would be contacting the Gliding Federation of Australia (GFA) and discussing your intentions with them. I've not had much to do with them in recent years but they always were a very helpful organisation in the past. Just something to keep in mind - if your thoughts take you along the path that many have trodden previously, you may well begin to entertain thoughts about something along the lines of the Goat but adding a small motor to make it self-launching. If so, just keep in mind that doing so wouldn't make it a motorglider because it wouldn't meet the span-loading and performance requirements of CAO 95.4, so whilst it would appear that almost any aircraft without a motor qualifies as a glider, adding a small motor doesn't make it a motor-glider. Even so, you could still add that motor and fly the aircraft but it would be a different category of aircraft from those controlled by the GFA. It would be an ultralight and would fit into the CAO 95.10 category which is controlled by Recreational Aviation Australia (RAAus) and you would need an RAAus PC to fly it. Similarly, if you made a powered two-seater it would also be registered by RAAus and flown with the same RAAus PC but it would be a CAO 95.55 sub-para 1.2 (e) aircraft.

I'm assuming this was in response to my post yesterday? You're saying "doubt that I see drops of heaps of knots......", well, no, you wouldn't, even if you were looking at the point of 'rotation'. Firstly, we're no talking 'heaps of knots', in the Sling example we're only talking 3.9kts low reading at the full stall. Hopefully, when you 'rotate' to climb attitude you'd be setting your plane and wing up at best L/D which would be at maximum 9 degrees AoA (alpha), that's only two degrees past where the off-axis pitot error begins, and given that pitot error is aomething like exponential with the extent of off-axis-ness, then at 9 degrees there'd be very little error in the ASI indication anyway. It might be just one knot at climb alpha. Secondly, throughout the take-off you're accelerating. If you weren't accelerating but instead you were running along the runway at constant speed just below flying speed and you rotated but didn't lift off, you might observe a small drop in the indicated airspeed, perhaps of about 1 or 1.5kts if you rotated to 9 degrees alpha. However, in reality you are accelerating during the take-off and so, if you looked at the ASI during rotation, you might see a hesitation in the advancement of the airspeed instead of a small drop. Regardless of the above, our ASI instruments are not what would be described as sensitive* instruments so a drop of 1 knot, or a slight hesitation might not even be noticeable. *An example of a sensitive instrument is an altimeter that has two pointers (the type with an adjustable subscale) where the scale of the longer pointer is divided into 10ft increments, one full rotation is a thousand feet. A non-sensitive altimeter is the type with only one pointer and the scale is usually divided into 100ft increments with one full rotation of the pointer indicating 10,000ft, or sometimes 5,000ft or 20,000ft. EDIT - Also - if your pitot and the ground are in fact parallel when sitting on your wheels, and assuming the fuselage is set level when on your wheels, then your pitot is actually angled down by 3 degrees or so due to the rigging angle whereby the wing is usually set with about 3 degrees angle of incidence to the longitudinal axis. In which case you probably wouldn't see a change at rotation.

I think he means it has less tendency to bounce i.e. becomes fast (fastened) to the ground better than a Jab does, doesn't he?

It's all part of the 'inconvenient truth', the question is though - should we open the proverbial can of worms ...? Some while ago there was a very informative thread called something like Do VGs really work and I think it was somewhere in there that Dafydd Llewellyn (Reg 35 approved aeronautical engineer) wrote up the story of the glider tug pilot who used to land his Auster tug at 32kts. If I recall the story correctly he'd been doing so for years and was quite certain of the numbers until Dafydd installed his calibrated ASI with swivelling pitot and trailing-cone static source test equipment. All of a sudden this Auster was landing at 48kts instead of 32kts. Now that's a massive and instant 50% increase, so what happened? The answer was nothing more than pitot error, and every single LSA out there suffers from it, and their unsuspecting owners are being duped daily ... The first thing is that we're all too trusting, and consequently we tend to believe what people tell us, particularly if it's written in an important document like a POH. I recall all the way back at the Mangalore that AUF was established, 1983 IIRC, I was having a chat with my old mate Sander Veenstra. He was an avid builder/manufacturer of ultralights back then, and I was going on about the performance figures of some new plane of the time. Sander laughed and said "you don't believe what aircraft manufacturers tell you, do you? They're the world's biggest liars - even worse than fishermen". I didn't say much more on the subject, particularly since Sander was an aircraft manufacturer himself and I didn't want to offend him, but I took note of what he said and since then have always performed my own analysis of aircraft manufacturers' claims, and it's mighty rare that any of them even come close to the truth. That particularly applies wherever performance limits are set by Regulation. One such limit we have in LSA/eLSA is the stall speed requirement. Very happily for the LSA manufacturers they get to self-approve their products under the ASTMs process, so no-one is out there actually checking the numbers they publish on their websites and POHs, it's all taken for granted under the ASTMs process, no-one will ever have to check it - unless, of course, someone decides to sue the manufacturer if something happens ... and good luck with that, I'd be pretty sure every manufacturer will be protected under several corporate layers much as the Robinson helicopter people proved to be when people had a go at them. Two things we DO know - without a swivelling pitot an ASI will almost certainly suffer from pitot error. AND - pitot error assists manufacturers' claims of lower stall speeds, since the pitot error invariably makes the ASI read low at high AoA i.e. when approaching the stall. It's well documented that airflow off-axis to the pitot by around 6-7 degrees or more provides a reading error which increases substantially as the angle increases to more than that. The stall happens at around 13-15 degrees for most airfoils and by that time pitot error can be substantial. A good example was my C172 where the ASI would read between 0-15kts while I was still able to keep flying under full control with full 40 degrees flaps and a very high deck angle. I even had some pax believing that we were flying at around 10kts .... There are a few ways to make the pitot error not so bad. Since there is very little effect on the reading accuracy below about 5 degrees off-axis, the manufacturer could point the pitot down by 5 degrees. That would mean the pitot error wouldn't start to become of great significance until 12 degrees AoA, so the reading at the stall would be a lot nearer the truth. So - do they do that? I wonder why not ... OK, so let's just for the moment suggest that just maybe there's a mistake in the POH of some LSAs, and the stall speed written in there is perhaps not the real stall speed, but is the indicated stall speed ... Is that possible? Wouldn't that be a bit fraudulent? Well, the answer is no it wouldn't be. The numbers written in the POH are NOT the true stall speeds, true Vne, true Va etc etc, they are the indicated speeds. The reason is simple - indicated speeds are the only ones we can use because the Air Speed Indicator is the only reference we have! So it's quite legit for the manufacturers to bandy around indicated performance figures instead of true ones ... AND there's no requirement for them to go to any lengths to make the indications nearer to the true numbers AND it's not to their benefit to do so. In fact it's to their benefit to make them read low at low speeds and high at high speeds. But they wouldn't do that would they? Would they? Just ask yourself how competitive the LSA sales market is and then ask yourself again whether they would or not. So - if that might just be the case, then what are the real numbers? There are two easy ways to find out. First is more fun than the second so we'll do that first. Load the aircraft to MTOW, strap in nice and tight, do all your checks etc, go to higher than 3000ft AGL. Determine the wind direction as accurately as possible by observation of drift, complete a clearance turn, broadcast intentions etc, cover the ASI so you don't cheat on yourself, point into wind, close the throttle and slowly bring the aircraft to a stall. Observe the GPS groundspeed. Do it again with half throttle, if the figure is lower do it again with more throttle until the stall (or apparent stall do to insufficient elevator effectiveness) speed doesn't get any lower. Once you've discovered the power requirement for lowest speed before wing/nose drop, do it again pointing downwind. The average of the two groundspeeds is your stall speed at that air density, you can apply a correction for the ISA air density if you like. Don't blame me that your plane doesn't stall at 40kts like the book said ... I'm just the messenger. OK, so you didn't like those results so what's the second way? We'll calculate it instead, that should provide a more pleasing result shouldn't it? Yesterday I provided a very handy spreadsheet, so lets fill in the boxes for a fairly typical LSA aircraft. You can all do this yourselves so no-one has to take my word for it. So let's put 600kg in the weight box, click anywhere else on the spreadsheet and see that the weight input then gives us 5886N (Newtons) for the mass. Leave the angle of bank empty since we want to know the level stall speed. Most LSAs have a wing area of 120-150sqft which is 12-15sqm so let's be generous and input 15sqm. A random click elsewhere shows us we have a wing-loading of 40kg/m^2, a quick mental check of 600/15=40 shows us the spreadsheet formula is working so far ... Next we input the wing's CLmax, that's a number (co-efficient) describing the maximum amount of lift the wing shape can generate in perfect conditions i.e. smooth air, smooth and clean surface to the wing, accurately built wing. We get that co-efficient from a graph showing the Section's polars. There are numerous websites which will show the polars for any airfoil, here's an example showing the Clark Y section, but most of the sections used for LSAs have reasonably similar CLmax, at least not sufficiently different to make any significant difference to the stall speed, more so to the stall characteristics i.e. how kindly or horribly the plane behaves at the stall. The one we're interested in is the Cl/alpha graph, alpha being AoA. We can see that the max lift co-efficient is about 1.35, so we input that to the spreadsheet. Good flaps will give you an extra 0.2 or so, so let's input 0.25 extra i.e 1.6 in the flaps box. Most flaps cover less than 1/2 the wingspan, but let's input 0.5 ( it doesn't actually improve the whole wing's CLmax as much as you thought does it? But it does significantly improve the deck angle and provides very handy drag as well as making it 'safer' because the inboard will stall much sooner than outboard, so less problems near the ground with wing-drops). Input .89 for the Aspect ratio factor, as our planes do fall in the 6-8:1 aspect ration bracket ... click anywhere and you have a stall speed of 44.5kts. Hang on, I hear you say, the POH says 40kts. But don't forget the 40kts is indicated, not actual stall speed. Well, at least our LSA is legal. Or is it ...? There are few things we left out unfortunately ... first there's washout. Many, probably most, LSAs have about 3 degrees of washout to help with the stall characteristics, so at the 'stall' only the first part of our wing is stalling, the rest hasn't reached the critical angle. The average is 1.5 degrees less than the stall angle, so let's have a look at that graph again and input the figures for 1.5 degrees before the fully stalled wing. On the graph it all gets a bit messy near the stall but in practical terms you'd drop about 0.1 to 0.15, so let's call it 1.25 instead of 1.35. The flaps setting won't change but irregularities on the wing's surface and build inaccuracies, and less than perfectly smooth air will bring the actual stall onset a little earlier, so for those factors, and just for the exercise, let's input 0.15 less on the CLmax, making it 1.1 instead. Oops, now our real stall speed has gone up to 48.6kts. well, that can't be true or the plane wouldn't be legal, so we'll forget about it because there must be some error in the software. I think we all get the point though? Ah, before we close the spreadsheet, just change the top number to 700kgs and then 750kgs and observe ... 52.5kts and 54.3kts. Another variable we can play with is the wing area, so let's input 12m^2 instead of 15, to see what some of the smaller winged LSAs do - yikes 60.7kts, we'd better not go there ... Back to your post Don - first, at all times let's keep in mind that we're not talking real numbers when we look at the ASI, it's just a reference that we can use in the cockpit, and it's way off anywhere near the stall. And we don't know how much it's off in any particular condition i.e. lightly loaded or heavily loaded, and we absolutely MUST NOT assume that the error is linear. If the POH is showing one knot indicated difference for 700kg, compared with 600kg, and we already know from the spreadsheet that the truth is 52.5-48.6=3.9kts, then it follows that the pitot error is exponential (actually more than that) at these high alpha, and that tells you that the sink rate near the stall is accelerating as the weight goes up, and that's a horrible recipe for disaster. OK, now we know we have a problem with performance that's getting exponentially worse as the weight increases. You've flown your plane at 500kg and, as you mentioned with the 'first solo' analogy, the difference between that and 600kg is remarkable, surprising, quite amazing in fact. Now, given that things are getting exponentially worse, would you really want to fly it at 700kg. Do you think that the performance would only be 700/600=1.167 i.e. 16% worse than at 600kg? I hope the examples above amply demonstrate that it's a lot worse than that - very much worse. The scary part is that, as you say, the increased speed for landing and take-off is fairly minor and on a cool day you might not notice all that much change, little enough to provide a rather unhealthy false sense of security in fact. The plane will actually cruise much nicer than usual as it doesn't react to the turbulence nearly as much as when it's light. More sense of security ... You've mentioned the landing speed being the main noticeable difference and perhaps that's just what you personally tend to notice more than other things. For me it would be much more about the take-off. And take-offs, statistically, are much more dangerous than landings. I'd notice the much greater use of runway to get airborne at all, the much longer time and distance required in ground-effect to reach a safe climb speed, the very much poorer climb rate and angle, the lack of runway left ahead to land on if the engine quits early, the proximity of trees and buildings on climb that previously were way below me, the long time it takes to reach a safe height for turning back if I needed to. The long time it takes to reach cruise altitude, the high fuel burn rate causing me to unexpectedly use some of my reserves before the destination, the much higher speed I need in the larger circuit I fly at the destination, the stall warning going off at the base/final turn ... glad to be back on terra firma, I'll fly lighter next time. Lastly - yes there's a huge trade-off with lift-enhancing devices (and even more so with a whole airframe designed for slow-flight capability) and cruise speed. You will probably get across country at 100+kts (130 indicated ;-) ) and I'l be doing so at 65 or so. My compensation is that I get to see more, land and take-off on 100m clear patch and I'll be having barra and oysters for tea, though I'll be late home if I get a few knots headwind ... In reality the (fixed) slats give about 6-7% increase of induced drag in cruise for the wing and that's all the wing drag increase when the flaps are retracted. The big drag increase is the large wheels (my tailwheel is about the size of your mains ...) and very long gear legs with long-travel suspension struts. Hope all this was helpful to some. Oh, and apologies to Jj for the topic drift but at least it's keeping the thread 'live'.

Testing the stall speed inflight isn't very difficult at all, and it can be very accurate, if the elevator has sufficient authority to actually stall the mainplane, which many don't particularly power-off. It might be a bit of an effort to do it for just one aircraft but if there was a plan to test every aircraft, for example, or every new aircraft, then it wouldn't be at all hard to have a dedicated set of equipment made available for the purpose. All that's needed is an accurately calibrated ASI, a swivelling pitot to attach to the front of the existing pitot head and a trailing-cone static source. The last is the hardest to organise but there's no real reason it can't be arranged to be deployed from a small cable-drum (with weak link) lightly attached to the pax floor, and trailing out of a vent or similar. Provided it was properly guided through a fairlead at the tail it needn't present any hazard while deploying or retrieving. And corrections applied to the indicated result for the air density on the day. BUT - that's totally unnecessary. The logical and much cheaper and 'fairer' process would be to provide all the evidence from the Lift Formula for any airframe. There are numerous software that will provide the CL Max for all standard airfoils and a very accurate CL Max for any non-standard foil simply by inputting the co-ordinates for the as-built wing. Factors can be applied for any particular airframe peculiarity and also for slots, slats and any type of flaps. I'd leave VGs out of the equation altogether since most aren't applied in any standard manner, and although they help to keep the flow attachment and detachment more predictable, they don't actually affect the CL (and hence stall speed) very much, they tend to have a greater effect on pitot error instead, due to the higher deck angle that people can become more confident with.

This assertion doesn't quite agree with physics. I think you'll find the difference is more like 3.5kts, but don't take my word for it. Courtesy of the UK Light Aircraft Association I have attached a very handy spreadsheet which will calculate the stall speeds for you based on the information you enter. If you input the data for your own aircraft you can discover the real effects of varying weights on your stall speed. It might surprise a few folks what their real stall speeds are but they'd be better suspecting the pitot/ASI setups than the spreadsheet. It's based on the correct formula i.e. Vs = √ 2 x M x nz/ρ x S x CL, where Vs is the stall speed, M is the aircraft mass in Newtons (weight in kg x 1g acceleration(9.8m/s)), nz is the load factor due to turning (to calculate the stall in a turn if required, otherwise enter zero for level flight), S is wing area in square metres and CL is the max lift co-efficient for the wing's airfoil. OK, well based on the above spreadsheet the difference between you flying your Sling with 1 PoB and half fuel - or flying it with 2 PoB and enough fuel for MTOW at 600Kg would be about 3-4kts on the stall speed. I don't know about the Sling but I find there's a massively noticeable difference between half fuel and 1 PoB or 2 PoB and MTOW on any LSA types I've flown, and that's just 3-4kts difference at the stall. I think this is what a lot of folks don't fully appreciate. I'm all for a weight increase on the basis of safer aircraft and cheaper aircraft by being able to use auto and motorcycle engine conversions and a higher percentage of commercial grade materials BUT I'm absolutely against simply having a weight increase purely on the basis that the airframes might be able to cope with it structurally, if it means that these aircraft would have a stall-speed increase to go with it. Try flying your aircraft light and then heavy as I described above, then consider what it would be like to fly it that much heavier again, because that's what the difference is to fly it at 700kg instead of 600kg, and it's much worse at 750kg ... If the increased weight aircraft have to get bigger wings to keep the stall below 45kts then I can't see a problem, but there are two things that concern me with a stall speed that goes up with a weight increase. The first is that the stall speed is based on an ISA standard atmosphere and so flying an LSA in the south in 15 degrees is a very different matter from flying one in the summer in the north. At 40 degrees and MTOW in Darwin you can sometimes wonder whether the runways are long enough and ground speed can be quite exciting while still being below flying speed ... And - not meaning to offend anyone but from what you see on the flightline some weekends there are plenty of folks around who find our aircraft quite enough of a handful at 45kts stall speed let alone any faster. Of course there are plenty of our folks that can also easily handle a Spit or Mustang but we're all flying in the same category and if we increase the performance there will be plenty of the less able folks who just have to have, and can afford, the faster planes and I fear there might be an accompanying increase in 'statistics' to go with it. There's really no need for a stall speed increase regardless of whether we have a weight increase. As someone mentioned above, just add VGs, slots, slats, and/or bigger or better flaps, or simply increase the wing area, depending on the 'mission' planned for the aircraft. My current 'DooMaw' build has much smaller wings than Don's Sling, and the same MTOW, but will stall about 7-8kts slower than his due to having various lift enhancing devices. Stall Speed Calculator.xlsx Stall Speed Calculator.xlsx Stall Speed Calculator.xlsx

Yes, I agree mate. I didn't mean it to appear to be an attack on you or your comment and I realise your purpose was to avoid causing offence rather than to cause it, but people can't be expected to change their signature line according to the thread or subject they're commenting on. I quite see your point though but I think it's one of those situations where occasionally PC won't be satisfied - and so be it, it ain't a perfect world ...

Well I noticed it and had a laugh, then went to tell my wife. I think it's funny! And PC has gone far too far already. Do we have to examine every last written or spoken word in case someone, somewhere doesn't find something quite to their liking? If we write or say anything at all there's always going to be someone doesn't like it. These days I'm feeling driven to being deliberately un-PC ... RIP to our fallen flying brother, and condolences to family and friends.

At an airshow I noticed that the Packard Merlins sounded quite different from the RR Merlins. I was told that it was because they had different firing orders. Anyone know if that is true or was the different sound for another reason?

I learned spin recovery when I learned gliding. I hated having to do spins at first but got used to them at least to the extent that they didn't bother me. Later I taught them in ultralight schools before the practice was banned. I didn't have any problem with a recovery until the day I was put through a similar 'blind entry' exercise to the one Soleair describes above. For all previous spins either I had made the spin entry or the instructor did it with me watching, so I knew which direction we were spinning and which rudder to use for the recovery. Later, when I was put into a spin with my eyes shut and couldn't see the entry, I didn't know which direction the spin was. I became really disoriented and confused and took precious time finding out. In fact the only way I did find out was by trying each rudder pedal briefly and observing which one slowed the rotation, and which one sped it up, and then using the appropriate one for the recovery. I was given the 'blind' entry several times and on no occasion could I work out which way we were spinning. Consequently I had to devise a means of instantly determining which would be the correct rudder pedal for recovery without knowing the entry condition. This might be useful to others, which is why I mention it here - I don't worry about which way the plane is spinning, instead I consider which way the ground is going and press the rudder which 'chases' the ground. If you're spinning to the right, the ground appears to be racing away to the left so I press left pedal to 'chase' the ground. During the spin it seems perfectly logical because I am subconsciously wanting to 'catch up' with the ground to stop it racing away from me. Using this mindset I can always press the correct pedal instantly without even thinking about it. And it works whether you're spinning upright or inverted. It probably sounds a bit odd when reading it sitting here comfortably on the ground, but if someone has similar difficulty that I had with recognising spin direction in the air, this method might just help them to become a lot more comfortable with spinning in general. Being able to handle a situation builds confidence and confidence in one's ability to recover accurately and promptly helps to take away the fear of the spin.

I though they were all radials. I could well be wrong but I've never heard of an FW 190 variant with an inline engine ... got any details OME?

Yes, I love to see the origins of things. I have to admit, though, that the title I used for this thread is a little misleading. Otto wasn't the first to fly at all, the Montgolfier brothers were, more than a hundred years earlier. And the first to fly a glider (sometime before 1849) is attributed to an unknown 10 year-old boy and then Sir George Cayley's coachman, footman or butler, John Appleby, to which you correctly alluded kasper. Lilienthal, though, became known as the father of free-flight gliding because he "was the first person to make well-documented, repeated, successful gliding flights".

A very clever animation created from a sequence of all the original photographs of Otto Lilienthal's historic flights that took place between 1893 and 1896. It's only two minutes long and well worth a look - [MEDIA=vimeo]155960641[/MEDIA]

27th January - 11th February 2016 Another couple of weeks. I've turned all those bits into two sets of adjustable pedals. Lots of drilling, jigging, clamping and fiddly small welding later, but I'm happy with the result. It was a bit of a battle to get the brake cylinder cleats properly lined up and uniform so I had to make a small jig from telescoping tubing and threaded rod, shown in the first image. I then made up the parts for the adjuster locking mechanism and it works nicely and is very secure, so there shouldn't be any accidental pedal adjusting happening at the wrong time. While I was in small parts welding mode I jigged up the parts I'd made some while ago for the bellcrank and elevator control horn and welded them, so the elevator centre section is ready for the addition of the hinges and the external horns which carry half of the pylon500 hinges (see post #91) that engage with the elevator control surfaces, and allow the the complete horizontal stabiliser to be folded upwards for trailering without disconnecting any controls. Following that I removed the fuselage from the project bench and put it back on its dolly wheels under the house because shortly I need the space on the bench to build the vertical and horizontal stabilisers and the rudder and elevators. I took a day out of the workshop to do the CAD work and CNC files for all the convoluted plates with myriads of holes in them for fitting the windshield, sheetmetal sides to the forward fuselage, firewall and cowling, and sent them off to the laser-cutting people for them to get started on. The material for that and the next stages of the project should get here in a week or so. Part of the material arriving soon is the thin CRMO sheetmetal for forming the ribs for the tail surfaces, they're .025" (0.6mm) CRMO sheet and it's cut into strips and folded into a C section, parallel 7/8' (22mm) for the fixed stabilisers and tapered 7/8" to 3/8" (22mm to 10mm) for the control surfaces. I had intended to get that sheetmetal guillotined up and folded in a sheetmetal shop but the folding is a fiddly and quite critical business that has caused me grief previously, and there are a lot of instructions to write out if there's to be any hope of them getting it right and not wrecking all my chromoly sheeting. So I'd far rather fold them myself. The problem is that the flanges are too small to fold it in a pan brake. A brake press is ideal but it requires a very narrow bed and not many workshops around here have one that small. I figured that I'd had good success with the tiny 4" (100mm) long brake press I made to go in my baby 6T shop press, for making the folded brackets a couple of months ago, so I thought that since the sheet for these ribs is only half the thickness or less, of the thickness of the brackets, perhaps I could make a much longer brake press the same way and fold them myself. The first problem was getting some control over the bed so that it didn't tilt as it folded, which would end up with one end folded to a much sharper angle than the other end. I won't try and describe how I made that side of it work, the pictures will show it much more easily ... The blade pulled and bent as I welded it of course, because I got the welding order wrong, but I linished and re-ground the edge straight again afterwards and once I got it working properly I folded the dummy tapered rib in the last picture from a piece of scrap colourbond as a test piece. It's worked out perfectly. It looks a bit wavy but that's not the fold, it's just a rough cut with shears along the edge of the sheet - once I get the proper sheeting pieces guillotined it looks like it should do the folding nicely. 77 more hours for the log, a total of 729 hours so far.

Individual pages don't seem to be any different from before but I've noticed the last couple of days that after clicking the 'New' button it just hangs for quite a while before anything happens. I timed it, it's a 6sec delay, might just be my internet connection though, but it's usually very fast. EDIT - After clicking the 'New' button, the thin blue progress indicator moves to about 10% and stops there for the 6secs I was referring to. Once it starts to move again the page opens quite quickly. I think that delay used to only be about 2secs previously. Having said that, it's only the mobile, the desktop seems faster than previously if anything.

Your error is in not having taken note of my word Original, regardless of the fact that you re-quoted my having said it. In case you're not aware of it, we're now on Issue 5 of the CAO 95.10. When it was original it was ANO 95.10, that was before ANO 95.10 Issue 2, then Issue 3 etc ... And back then there most certainly wasn't any demonstration of compliance REQUIRED before registration, most particularly because there was no registration, and no licencing, and no membership of AUF/RAAus because there was no AUF/RAAus, it was just like Pt103 in USA is now - as I said ... Though what your point in contesting it is quite beyond me. If you doubt what I said I can tell you that in a decade in the late 1970s to mid 1980s I built more than a dozen 95.10 aircraft and sold many of them, only the last one was ever registered (once registration was available) and none were ever required to undergo any proof of compliance. During the same period there were also a multitude of other people building aircraft under 95.10 in Australia, the vast majority of the aircraft would never have been able to be shown to comply with the requirements, mainly due to being overweight and over the max wing-loading, and none were ever 'tested' for compliance regardless of their non-compliance being common knowledge and in many cases blatantly obvious. Additionally there was a score or more of imported kits and fully assembled aircraft, their production mainly aimed at the USA Pt103 market but just as well suited to our early version of 95.10, before the various changes that came with each new Issue. Some of the Aussie names that come to mind - SV Aircraft from Sander Veenstra, Robbie Labahn's Rangers and Hitchhikers, Wheeler Scouts, Cohen's Condor, Wakelin's Javelin, Kimberley's SkyRider, Betteridge's Hornet, Winton's Jackaroos, Grasshoppers, Sportmans, Bekker's Blue Max, the first Thrusters, and the list goes on. The imports included the Quicksilvers, Pteradactyls, Kasperwings, Mitchells, Weedhoppers, Rotecs, Falcons, and so on - and not one of them ever had to show any evidence of compliance to anyone - just like Pt103 funnily enough.

Has anyone come across a smiley/emoticon for 'shakes head in disbelief ' ...?

Did I say that Pt103 operators had to demonstrate something/anything prior to operation of the aircraft? What's your point exactly? Which part of what I said is wrong ...?

Yes, that's a very good, practical and workable concept but once again it's no good just RAAus adopting the method, it would need to be introduced into the ASTMs process as the required evidence of compliance because the Oz market is too small to make any non-Oz manufacturer introduce design changes to their standard models just for us. To use the calculated CL from the 2D polars as the stall-speed calculation criteria there would also have to be corrections applied for the percentage of the wing that is flapped, the amount of washout and the construction method, since a fabric wing is not as 'true' as a composite wing and a metal one is somewhere in between. But on the whole the concept is a good one which would remove a lot of the onerousness of proof-of-compliance. They have something similar in USA for their Pt103 aircraft (similar to our original 95.10 aircraft) whereby they don't have to demonstrate minimum controllable speed/stall speed of below 24kts if they can meet the requirements of a formula which takes weight, wing area, number of surfaces and drag from wires and struts into account, works better than the 24kts limitation for some designs.

A good analogy OK. Level playing field ...? Well more like an open can of worms that's still standing upright ... for now ... really. When Jabiru first did their testing they had a very lightweight KFM engine and I had the chance to fly that early prototype back in about 1977 or 78. It was a quick little thing even with that light engine and several of us who flew it reckoned that by comparison with what we had been flying up to then, owning a Jabiru would certainly warrant paying regular allegiance to the God-of-very-large-flat-empty-paddocks, just in case the donk didn't do it's regular thing on any particular day. Then Jabiru built their own engine and I think the approval trials for 95.25 were conducted with that new engine - but that was the little 1600cc wasn't it? When they later built the 2200cc because the 1600cc wasn't putting out anything like the expected power, IIRC, they certainly had the bigger engine certificated but I don't recall anything being done about re-testing for stall-speed compliance. Maybe they built a bigger wing? Maybe they did the testing but I didn't hear anything about it, that's more than possible ... or maybe the 2200cc was the same weight as the 1600cc? Wasn't the 95.25 approval based on a 450kg MTOW? I really don't know but certainly Drifters were, and Lightwings were, the Thruster was, not sure about the Skyfox, but I thought so. Certainly Howie beefed up the Lightwings before some of them were allowed to increase to 480kg, and the 544kg airframe was much stronger again, then some folk wanted to fly them at 600kg. What about those who built their own Jabiru 160s from a kit? I personally know of at least one that started life with a 4cyl 1600cc and now has a 6cyl 3300. I suppose the stall speed remained the same? I've flown it a few times, it feels like it lands at least 50% faster than my 172 used to ... Because of all the above and what I pointed out in my previous post I'm pretty confident that just about every factory LSA out there is already pushing the boundary as far as getting within the stalling speed at MTOW and in ISA conditions. It's easy to load a plane lightly and go flying on a cold day (as it mostly is cold in Europe where the majority of them are built), have the benefit of pitot error and then claim the stalling speed is whatever the ASI reads at that light weight and low ambient temperature. So just for a moment lets say that they some of them might be pushing the stall limitation just a little and perhaps they're actually a knot or two over ... If that were the case then I'd say this whole discussion for a weight increase to 760kg (or whatever) is nothing but a pipe-dream. Unless the increased weight class was global, and also went with an increase in stall speed, all those European manufacturers aren't going to re-design their aircraft with larger wings and consequent support structure, or design wholly new aircraft, just to satisfy the tiny Australian market. That demand for more weight isn't being heard in Europe and USA because they don't try and use their recreational aircraft as non-stop transcontinental commuters as some here seem to want to do. To be fair, they don't need to think that way over there because there are unlimited places to plan fuel stops whereas in Australia it's a lot further between them once you leave the coastal fringe. If there was a stall-speed increase to go with the weight increase then the same wings could be made to do the job with a little extra strength where required, but the extra weight at the same stall speed makes it virtually impossible with the same aircraft especially when the stall speeds at the present weight just might be already being squeezed a little ... In fact, if there was a stall-speed increase to go with the extra weight then the manufacturers are already making those types of planes to suit the RPL class of 2PoB and MTOW 1500kg - the new bottom end of GA.

Factory aircraft ... tested by whom? And demonstrated to whom? Sure your comment about 95.10 is correct, and in fact the wing-loading requirement of 95.10 results in 95.10 being the only truly 'honest' class out there. It's a shame it's impossible to build a plane in 95.10 unless you design it yourself (given that RAAus haven't 'Approved' a single set of Plans or any kits in the last 25 years - or ever come to that). It's pretty well universally assumed that just because an LSA is factory-built, it must actually comply with the LSA design requirements because it's assumed it's "been tested to demonstrate compliance with a maximum stall speed for a class". But there's the rub - does it actually comply? None of the new wave of 'slipperies' and 'plastics' has ever had to go through what our early Jabirus, Lightwings, Skyfox/Gazelles etc had to go through to get recognition as complying with the then 95.25. All the current LSAs that fit into the newer 95.55 category haven't actually been through any independent compliance testing at all, their manufacturers simply sign them off themselves, declaring that they comply under the ASTMs program. Many of them were 'factory approved' when the weight limit was 544kg, then it went up to 600kg. Isn't it a bit odd that many/most of the aircraft that complied at 544kg didn't change at all outwardly but suddenly some were factory-approved at 600kg. What happened, some might ask, that one day they stalled at 44.5kts (according to their POH) at MTOW of 544kg, and the next they stall at 44.5kts at MTOW of 600kg (according to their revised POH)? Was everyone so busy arguing about whether the airframes were strong enough to carry the extra load, that no-one was concerned about the extra weight affecting the stall speed? Some of the more responsible manufacturers even found they had to add strength here and there to beef up the airframe to carry the extra weight. I guess that extra structure reduced the stall speed huh? As has been pointed out in earlier posts, it's not easy to definitively determine the actual stalling speed of a flying aircraft. When Dafydd Llewellyn did it properly for the Jabiru testing, he installed a fully calibrated swivelling pitot with trailing cone static to ensure the airspeed readings were accurate at all deck angles and AoAs. Has anyone ever seen any evidence of LSA manufacturers doing that to 'prove' their aircraft under the self-assessed ASTMs code? I seriously doubt it, after all, there's no requirement to do it and where's the incentive to do so voluntarily? I'm sure we're all aware that a pitot only provides reasonably accurate dynamic pressure information to the instrument when its axis is aligned quite closely with the airflow. By 7 degrees off-axis it's starting to become inaccurate and by the critical angle (or stall angle) the ASI is reading way below the real airspeed. This plays kindly into the hands of the manufacturer - how many times have you heard folk in the clubhouse telling how their Superscramblejet LSA cruises at 130kts and stalls at just 35kts! Having flown in a good selection of them and with a healthy dose of ASI accuracy skepticism, I'd estimate that very few actually stall at less than 45kts when at max gross weight. I don't have the reference at hand because it was a few years ago that I looked into it but no doubt could find it if anyone wants to take me to task about it ... and I'm also working from memory - but another point about the ASTMs factory self-approval process is that if, for any one of a number of reasons, the factory finds it 'inconvenient/difficult/impossible' to obtain sufficient data to satisfy themselves of compliance in whatever matter they're currently 'testing' then they can resort to satisfying themselves by calculation that it would comply if they could have been able to test it satisfactorily. I wonder how many of them, then, decide to accept their own 2D airfoil analysis to come up with a theoretical CL which just happens to work out well with their favoured wing area, rather than doing it the other way around. Should they choose to do that (which the ASTMS process completely allows) then they need pay no notice to the usual physics, whereby the real wing in 3D has considerably lower performance than the simple 2D airfoil polars might have you think it would. The graph takes no account of tip losses or lift reduction due to washout, for starters ...

Not meaning to be disagreeable Kasper, but my 912ULS has a 'fail to WOT' system, not to closed throttle. So if the primary throttle cable breaks (or disconnects for whatever reason) then both carbys go to full throttle. Or if either of the secondary throttle cables disconnects after the splitter, then the carby on that side goes to full throttle. On mine that's how the carby spring-return system was set up from the factory, and is the reason that many of the 912 powered planes I've flown have a tendency for the throttle to creep open while taxiing, due to the return springs being at 'full stretch' when the throttle is at idle, or at a low power setting. Is that something that only the newer R912s have, or has the system been reversed on your trike, perhaps?

Nice post FM. Yup, I agree about the name things you brought up. In Europe they have got around it by calling what many of us fly these days VLAs i.e. Very Light Aircraft, I think it's their category above the 450kg ultralight/microlight class and below 600kg. Then above that is Light Aircraft in General Aviation. As you mention the word "ultralight" seems to conjure up images in peoples' minds that are probably a bit negative for us these days, so perhaps we should be thinking along the lines of promoting the 'Very Light Aircraft Flyers' Association' banner? Or "Lightweight Aircraft Flyers' Association"?