Oscar

Having been one of 'the people standing beside the runway', (at Hoxton Park!) for the Australian Twin Otter performance chart figures, I have to say DJP's commentary is spot-on. Mind you, when Randy Green landed the bloody thing on full beta thrust and ended up his roll-out traveling backwards, it made a nonsense of the thing ( but beta thrust was not allowed for the official P charts). But it was farging awesome to watch! I reckon he could have put it down in the SCG and ended up at the nearest crease. However, for determining proper POH figures, a bit more than just recording what appears on the ASI is necessary. To do it properly, you need a calibrated, free-swinging (in both vertical and horizontal planes) pitot probe that is NOT influenced by position error - and those are few and far between. That provides the correction table between true airspeed (TAS) and ASI reported airspeed (AIS). And TAS vs. the figures one sees in manufacturer's blurbs for stall, VNE etc. can become very sobering. To produce a POH for a manufactured aircraft that will withstand audit, requires test-pilot skills. Certification authorities do NOT hand those out as a cut-out-the coupon on Cornflakes packets. Ask Keith Englesman. PS: in earlier days, test pilots used to throw eggs out of the cockpit downwards to record lift-off, touch-down etc. points. No doubt many proto-chickens died - but probably, very few pilots!

Bruce: if you are looking for more directional stability in cruise rather than just pure rudder authority, you need to be very aware of the interaction between vertical area and dihedral. In the case of my aircraft, with a significantly increased fin and rudder area, it will require more dihedral - so we are planning adjustable test lift struts and ultimately, new struts once the flight testing has determined the ideal amount of dihedral. Flight testing is the only real way to get the balance right! Get that balance wrong, and you end up with an aircraft with a harsh Dutch-roll motion. Jabs - LSA55s especially, and I think the SK has the same fuselage length? may wander a bit, but they sort of waddle along without making you airsick. Too much dihedral is ALSO lousy for motion in cruise; I've flown in a Rallye, which was a like a pig chasing truffles at the gallop in cruise. Seriously - sitting in the RHS beside a CASA-approved Test pilot, I had to do the navigating because he couldn't afford to take his eyes off the horizon lest we both barfed.. A minor addition of rudder area shouldn't produce any major changes, but if you increase it substantially, I seriously suggest you are embarking on a journey of chasing your tail ( pun intended, there!). May I politely suggest that before you attack the rudder with 'glass - try gap-sealing it. A brush-type seal might improve things for little effort

Bruce: be careful if adding any chord to either surface. When transplanting a UL ( or J120) fin and rudder to my ST1, I found the rudder was a very poor fit to the rear of the fin and modified it to be a better fit. HOWEVER, when doing that, I was advised strongly by an aero-engineer who had done the test flying on the early Jabs. for Certification purposes, that the maximum safe c.g. change to the balance of the rudder should be no more than a 5% rear shift behind the hinge-line. I would imagine that much the same rule of thumb would apply to the elevator.

HITC - class work, as always. I think you may be well served by moving the O/C away from the spinner. The advice given to me is that in the immediate area of the spinner, you tend to get small/negative air pressure due to the separation of prop-blast air around the cowl (sort of like an inverse venturi, I suspect) and immediately behind the spinner you will get reverse airflow past the shaft out to the spinner edge at least.

Nev: these turkeys are running (if anything!) something like Supertrapps with most cones removed. (or is it the other way around, to make more noise?). but it's the endless 'light-switch' throttle movement that is the real problem. WFO-Close-WFO in about 5-second bursts, for 8 hours or more. They are utter wankers; I've only done a limited amount of dirt riding but even that taught me that just digging the rear wheel in everywhere is NOT the way to make decent progress. The pros get the power to the ground by graduated throttle control, wankers just spray dirt everywhere. My place lies directly under the best track from Bankstown / Camden / The Oaks, to the South East. I get everything from ultralights from Mittagong (about 9k away) to Blackhawks heading for Nowra over my place. On a decent day, 5 - 10 movements. The only aircraft that come anywhere near the annoyance factor to the mx'ers ( or faux mx'ers being used as trail bikes) is Alan Friggin Jones's charter Jetranger blasting over at about 150 feet enroute to/from Mittagong, and a couple of times, what I think was an early Queen Air with augmenter exhausts. The local Warbird fraternity practicing formation aerobatics in their Yaks / Numchuckas nearby, are just a relaxing drone.. Ultralights passing overhead, are mostly done and gone from the first moment I hear them, before I can change my glasses from close work to distance, to check them out. Trucks on the jake brake past my pace are WAY more disruptive.

Try an amateur motocross track 1 KM away... with 8-10 hours per day in summer, of an unmuffled bike/bikes doing the 'throttle full open - throttle full closed - throttle full open' routine every 30 seconds for that whole time. I had that until recently, and I got to very close to homicidal.. and I am a pretty ancient motorcycle rider. And a bit deaf - but nowhere near deaf enough..

As 'replicas' go, it's not real flash, for sure. But probably a lot of fun in return for the years of work. But there are some far more serious issues arising from this report. The noise issue being raised as a serious objection, and apparently being taken seriously, is something that plagues Recreational Aviation. It seems to be a given, that any aircraft operation nearby is an intolerable noise source - we are 'guilty' even if we can PROVE innocence. One take-off and landing a day, probably accounts for at a maximum, 5 minutes of noise over adjoining properties a day. The comment that 'it is like standing next to a jackhammer' - give me a break. I've had a Thrush Commander on Fire-bombing duties lifting out from around 500 metres away, maybe at 60 feet over my house, fully laden and on FULL noise - and it shakes the shit out of you. But it's done in about 30 seconds; x maybe 10 sorties a day, is 5 minutes. The fire-bombing choppers might do 20 sorties a day, not a lot less noisy. The property opposite me, from where they fly, is a home to a heavy trucking company - serious B-doubles, low-loaders etc. I am awakened at all hours by them coming and going, on the jake-brake for a kilometer or so before turning in, up through the gears on leaving with 40-50 tonnes of load. But there is no point in complaining - after all, it may be noise, but it's commerce, right, so STFU and buy some ear-plugs. We NEED, for our survival, to be conscious of the noise we make.

Occupant protection in 'ultralights' (up to and including LSA aircraft) is almost non-existent by design rule, by comparison with the FAR 23 requirements for both spinal (crush) and head/neck (flail) injuries. Overturn accidents are very common in 'ultralights'. I have a (very early) Jabiru, which I have been re-building following what was evidently a fairly light overturn accident. Now, Jabirus play 'dead ants' quite a lot, but they still have a remarkably good occupant survival record - this is, I think, a pretty accepted fact. People have walked away from Jab. accidents where the things have been torn apart at the firewall with amazingly little injury. Now, in the case of my Jab., the cabin roof had been impacted and the gel-coat and some of the roof 'glass cracked quite a lot - required a significant repair. There was a small amount of blood on the head-lining. The LSA55 Jabs are pretty tight in the cabin area, one would have thought that the roof deflection was the cause of that blood. But closer inspection and evaluation of the damage, showed that the headphone 'hanger' bracket - which is well aft of one's head in normal seating position, and aft of the main bulkhead behind the seats - had been bent in a way that was consistent with having been hit from ahead and below - i.e. by the pilot's head having been flung backwards, upwards ( in relation to normal attitude) and towards the centre of the aircraft as the thing hit the ground inverted. Jabs have the usual - and by regs, completely acceptable- three-point harness. My Jab had been certificated - meaning it was a factory-built, (and originally VH-registered) aircraft, meeting BCAR S, and with basically TSO'd seat-belts ( the release certificate on the seat-belts was still intact, and valid). The Jab. harness is very appropriately positioned for both lap and sash restraint angles for spinal crush protection.. Basic analysis of the evidence suggests that in the overturn case, a three-point harness allows the body to twist and rise from the seat, throwing the head initially forwards as strong declaration occurs as the front of the aircraft digs in, then rapidly backwards as the aircraft somersaults and the residual forward energy (relative to the occupants) becomes rearward (relative to the occupants) energy to be arrested. In the tight and fairly flimsy space of an 'ultralight', there is very little room for head 'flail' before some part of the aircraft structure is impacted. Post #23 argues that 'this has been largely sorted out' in motor vehicles - which is fair comment: the ANCAP safety standards have effectively mandated curtain airbags for this reason, I believe. In my opinion, in view of the constricted area and nature of an overturn accident kinetics, a three-point harness is pretty poor protection. However, the bloody stupid weight limitations on 'ultralights' makes it very difficult for designers to improve occupant safety. Yes, there are some 'ultralight' / LSA-class aircraft that have at least four-point harnesses ( I believe a five-point harness is a far better option, providing anti-submarining capability for spinal compression safety) - but they need to be properly anchored. Just because there are two shoulder-straps installed does not necessarily mean that you have additional security. I examined the Goulburn Sting double-fatality wreckage, and the shoulder-harness attachment points had failed and torn out of the structure. I have photographs of that damage; however, it is not something that anybody would want to see produced publicly. Basically, we Recreational aviators fly under a regime that - due to a bloody ill-considered and rather ludicrous MTOW - produces aircraft that have minimal occupant safety. In flight performance aspects, they are really rather cost-effective and viable devices, but in terms of secondary safety they are heavily constricted for capability. Or - to put it in rather more emotive terms: they are good, until it goes bad.

ATSB investigating a 55-reg non-fatality?????????????

To fly a Gnat, was for so many years an enduring dream for me - something about it just hit the sweet spot. Strap it on and go play.. But it was apparently a very complicated aircraft, though it was designed for lower-tech manufacturing techniques than the top-line stuff. Amazingly - to those of us ( and I am guilty here) who long-regarded Indian manufacturing incapable of making anything more complicated than Royal Enfield motorcycles and a badly-executed clone of an Austin A40 for taxi duty - the Indians actually produced and very successfully flew Gnats for many years!. And - to defend myself from charges of even FURTHER hijacking of this thread, W.E.W Petter who designed the Gnat also was one of the original designers of the Lightning!

Concorde was a pussy. It has taken me years of research to discover all of the below, but it will put things into perspective.. Concorde's performance was primarily driven by the urgent wish of the British engineering team to design something that would get them far enough away in jig time from the daily influx of garlic eclairs delivered to the French design team. In that it was successful. The Lightning performance was a result of the design team being subject to a 'disproportionate response' from the locals who were awakened at 0400 every morning by the Commer Knocker milk delivery truck to the design office. A basic requirement was a climb rate in excess of the muzzle velocity of an ex-WWII Bren gun owned by one of the locals...but in the end, required advanced pilot skills for the first 5,000 feet. The Blackbird.... used engines scavenged from the Roswell alien craft and copied... burning hyper-nuclear ping-pong balls.. Afterburners? Ha. THIS is an afterburner run.. OK, Phil, I apologise for completely hijacking your thread. It's a hot and dreary afternoon here in Oz..

I've never seen a Lightning in the flesh - even at Duxford (unless my memory is worse than I thought) but they have always reminded me strongly of a somewhat cynical comment made by an aero-engineer about the different philosophies of the Yanks and the Poms towards designing fighters. The Yanks, he reckoned, get an armchair, a decent number of heavy weapons, arrange them on the hangar floor in logical positions and then say to the designers: 'now, make that lot fly'. The Pom approach, he reckoned, was to draw up a specification and let the designers loose to do wondrous things. Around 2/3rds the way to finishing the prototype. someone would say: 'Um, what about a pilot?' whereupon someone from the design team would say 'we'll dig a hole somewhere up near the front and stuff in a stool, somewhow'. Probably most unfair...but the guy in the back-seat of this F-15 looks as if he's waiting for the kettle to boil to make the coffee while they aerial re-fuel..

As for climb performance... ( and I don't mean to hijack the thread!).. McDonnell (as it was then) sent out an F-15 Eagle for a demo in Australia. It did an aerobatics display over Lake Burley Griffin, with our then Minister of Defence sitting in the back seat. As it happened, I worked with his daughter at the Australian National Library - situated on the foreshore of the lake - so we climbed onto the roof of the Library to watch it. The demo pilot did several loops over the lake, the best display I have ever seen of managing pure power and drag controls to do them slowly - every one of them had a lower base height than us, only three stories above the ground - maybe 50 feet above the water. The F-15 was beyond awesome, there is no sufficient word. When the F-15 left Canberra airport the following day, the Tower asked him to report when clear of the (upwind) threshold. Which he did, with the laconic addition of 'passing through 20,000 feet'. Smartarse.

I presume - but don't have the technical knowledge to even know whether it's possible - that since the Lightning had climbed on a 'ballistic' - i.e. near vertical - flight path and had so much height, it would gain enough airspeed in a near vertical descent to re-start the engines?

Probably legend, but... a story goes that when the USAF made the first flight of a Blackbird into the UK, it landed, and shortly afterwards the UK Station Commander came over to the pilot to express his admiration for the thing. The Blackbird pilot said something on the lines of: 'Nothing can get near us', whereupon the UK Station Commander handed him a photo of himself at the controls, high over the UK... taken by a Lightning that had intercepted the Blackbird at the very top of a 'ballistic' climb where the Lightning's engines had flamed out due to excessive height but he still got the photo..

Having done an extensive rebuild of a Thruster (my nephew's) after a light crash - including replacing the main tube, wing struts, and a lot of incidental work, I would say that 'good as new' -even if correct - would not be sufficient encouragement for me to even walk near it with the engine running. I've seen better bloody engineering on a Manly Junior sailing dinghy...

Gentlemen: retire to neutral corners...

Having done a few for my racing car projects, I can confidently say - they ARE a bugger to do by hand.. I tried all sorts of tricks to get some heat-sink on the inside to minimise the 'spurts' of metal - none worked well. Sequential 'spotting' with a MIG with 'spot'-capability is a possibility, but though I have such a beast, I've never tried it on tube joins. Your result looks very damn good to me. Of course, there IS an easier way.. Here's one: All you need is a large supply of titanium tube and all the robotic fabrication capability of Honda Corporation! And a casual budget running into the multiple $Ms for the project. Easy as...

jj - I concur entirely. I want to see the Gen 4 succeed, for the sake of all Jab. owners, since we no longer have the alternative of a CAMit engine. Bruce's original post #187 says to me that Jabiru are really pulling out the stops so this is the result. What all we Jab. owners need, is good feedback on experience of the Gen. 4 engine. NOT speculation, or cant.

Bruce, it is my understanding that the heads are screwed on - a la Lycoming, Continental, all (I think) the big air-cooled radials etc. I believe ( but could well be wrong here, those engines are way outside my experience) that that can sometimes be a 'one-shot' process i.e. mated for life. Edit: jj has confirmed my belief, while I was writing it up! I am intrigued: did Jabiru send Gawler just replacement barrels or complete 'jugs' - pots plus heads, ready assembled?

With respect to the knowledge you and Kensla obviously have, may I suggest a couple of things. Optimum ambient conditions for this work would be around 22-24C and not a lot more than 30%RH. Preferably, several days of RH around that figure before the repair. Prop off the aircraft and the repair set at zero degrees to ensure the resin flows evenly around the de-lam area. Drill with around 1mm holes at the peripheral of the delaminated area to ensure the influx resin gets to the edge of the de-lam area, and inject from the centre until all peripheral holes exude resin.. Work it around by thumb-pressure. Wrap with cling-wrap - and if you can organise even a crude vac-bag using a vacuum cleaner and some builder's plastic blanket ( but have the vacuum-cleaner running on low vacuum setting so it doesn't burn-out!), you'll get a damn good result. You'll need to run the vac.bag for around six hours at about 22C to ensure the resin has gone off. Take a test coupon of the resin - if it breaks cleanly (not shatters into shards but doesn't just indent), you've got a good result.

Oh, YES!. Almost all my experience is gliders, and we wouldn't start the day normally until the thermals were starting to pop - essential if you were going to do anything but a slow circuit.. But I used to try to also get the last launch of the day, when the air has flattened to velvet, the sky is a serene darkening blue and the ground is mostly indigo. No lift, of course - you'd bung off the tow at 2K AGL, trim for best L/D (about 60 kts for most gliders) and let the serenity ( thank you, Daryl Kernighan!) just seep through your bones. Land, and taxi the thing up to the hangar door. Worth the launch fee, every time. FWIW, (and I'm NOT trying to bang the Clifton drum here!) - but it's a grass strip so doesn't retain accumulated heat from the day as much as bitumen would. Has a bit of slope to keep you on your toes, but very clean approaches.

Unless Jabiru has changed, they use Araldite LC3600 ( but best check with Kody). CG Composites sells it in small quantities at reasonable price - the postage for 1 litre of it may well be more than for the resin itself because of the 'Dangerous Goods' classification. Note - LC3600 has a definite shelf-life, don't use 'old' stuff!

DK - have you thought about Clifton? It's 30 minutes up the road from you... Avgas and Mogas on pump, a clubhouse and accommodation attached, great people. You'll never find a family more attached and committed to ultralight flying than the Banges. Webcams on the field so you can check the local weather from home over your morning coffee. You'd need to join the DDSAA - a whole $50/year, from memory - and be prepared to go up there sometimes to help out with airfield maintenance. Seriously - the whole ambience at Clifton is wonderful. I know Warwick well, and Clifton and surrounding area - great place to fly, just for the damn fun of it. Tootling along at maybe 700 AGL through the surrounding ranges, shooting the gaps anywhere down to Gatton or up to nearly Toowoomba - a tonic for the jaded soul. It's sad to see a long-time aviator ground down by an unfeeling Council, and the costs involved. I seriously recommend that - before you fire-sale your much-loved aircraft - at least organise with Trevor Bange to go on a flight around the area with him, and discuss the costs of re-locating to Clifton.

The transfer of regional/local airfields to Council ownership was the parting 'gift' of the then Leader of the Nats. and Minister for Transport, John Anderson, to Australian aviation. A more cynical act with the entirely obvious ultimate result of depriving regional communities of facilities to support not just the regional transport network but the development of tourism, support services for medical, fire-fighting and flood (at least sometimes) relief work, is hard to imagine. After water, power, communications and roads, airfields may not seem such a prominent 'player' in the game of keeping regional communities connected with the major centres of population, but they CAN play a role in local community life, providing incentives for local development and acceptably 'connected' - rather than isolated- places to live and work. The growing capability of RAA-class aircraft makes this 'connectivity' more viable at sane cost. In my view, John Anderson sold out regional communities by that act.