Bob Llewellyn

Hi all,Has anyone here had any experience with round/circular/disc-shaped wings?

 

I know that they aren't popular and there were many experimental designs towards the end of WWII like the Vought V-173 (http://en.wikipedia.org/wiki/Flying_Pancake) and the Sacks AS-6 (http://en.wikipedia.org/wiki/Sack_AS-6)

 

I've heard that this design is very unstable, but David Rowe in NSW has built an experimental version known as the "Useless Flying Object" (UFO) and there's a YouTube clip showing it flying quite happily:

 

For a 300kg 95:10 machine, at a lift coefficient of 1.4 the induced drag will be 68.4 lbf (304N odd). This lift coefficient corresponds to 36 kts, making the induced drag power 7.6hp. By contrast, the mighty T-83 (Thruster) has an induced drag power at 36kts of 1.5hp.

With a streamlined bump for the pilot, the disk wing would have a (minimum) total drag of ~78lb, plus ~2lb for the engine cooling (if cowled well) and ~9lb for the U/C as shown. The power for level flight would therefore be about 10hp, on a thrust hp of perhaps 20 (prop inefficiency eats the rest), giving a max ROC of 500fpm on a rotax 503. Funnily enough, my T-83 with a single-carb, points ignition 503 also gets 500fpm...

............toad cuddles with the club bitzer before................

You would have to be asleep to have a control problem with a twin and engine failure in cruise. You will have to get lower straight away in a Jet, as you lack the power to stay where you are. but you still don't have an assymetry problem of any magnitude. Where you get into strife is getting too slow so the rudder loses the effectiveness to keep the plane from yawing. Below VMC (a).This is most critical on initial climb out, where the performance may be very marginal as to climb gradient or if the approach is misjudged, and you get low and slow, then . Nev

You would have to be asleep to have a control problem with a twin and engine failure in cruise. You will have to get lower straight away in a Jet, as you lack the power to stay where you are. but you still don't have an assymetry problem of any magnitude. Where you get into strife is getting too slow so the rudder loses the effectiveness to keep the plane from yawing. Below VMC (a).This is most critical on initial climb out, where the performance may be very marginal as to climb gradient or if the approach is misjudged, and you get low and slow, then . Nev

I have been at Ole's factory a few times, lovely straight up guy and he takes his engineering on the safety side of it very seriously, chome moly frames are extremely robust as is the trailing arm suspension and the intergration of it all. If you're going to have a crash an AAK isn't the worst place to be.He does suffer a weight penalty though for it all.

Would airbags increase survival rate and reduce injury in jabs during forced landings? It's cheaper than a chute. I am just brainstorming…

The Comper Swift used ONE .(Originally as most had other s fitted later) Didn't the DH Dragon Have one of the biggest payload / HP ? 2 x 130 HP Gypsy 1-c's.Talking of Payload etc I recall an airline at Tullamarine .

They taxi out in their brand new Short Skyvan. Tower says/ What Plane is THAT?. Skipper(proudly) THAT is our brand new SKYVAN.

 

Tower .. Haven't you unpacked it yet? ... Nev

The point I was trying to make is that twin engines increase safety, especially when flying over tiger country, provided the aeroplane isn't loaded so heavily that the engine-out handling is razor-edged.

Cri Cri's have a fairly high stall speed. Doesn't that rule them out for RAAus?.Comparo ( I 914 to 2 503's ... 1 x 924 x4 strokes = 3896.

( 2 x 503 x2 strokes. = 2012 . The 914 wins easily.. Any other comparisons you want me to do? Very small charge... Nev

Hey, the Short Scion used a pair of Pobjoy Niagaras, and look at its load factor...

BREAKING NEWS ................... BREAKING NEWS ............................ BREAKING NEWS 

 

Knowing what passionate monarchists the Welsh are, for Bob's sake I felt compelled to break into the NES with the latest, just in from one of my mates at Scotland Yard, following a fracas in Knightsbridge last night where some Greek bloke got glassed ..................

 

Negative........ 25 was factory built certified trainer........the weights I posted are from the factory placard attached to the aircraft.....Maj...

and what is the difference between the two?

Cheers Davo

P.S. see you at Old Station

95:25 aircraft were issued with Certificates of Type Acceptance (or Approval, CASA used both wordings); so 95:25 aircraft are certified and approved (or accepted!). 101:55 aircraft ditto, but if a recognised standard such as JAR-VLA were used under 101:55, a Type Certificate could be issued.

The difference is that a CTA is valid only in Australia; an Australian Type Certificate is acceptable in any ICAO country. This is good news for any international airline operating under RAAus...

Yep twice as much.

If the impulse fails just swing it faster. This is a risk with the non impulse mags, as they are still fully advanced, whereas the impulse one is retarded. You usually select Impulse magneto only (STBD for the DH 82 from memory.) My Citabria had impulse on both. Started like a dream with priming pump, (or manual, Armstrong). Nev

Either way...haven't managed to overload it yet.....and it still gets off in 200 mts with full fuel and a prop pitched for cruise .....thank you Howie.....Maj......

The FAA declared their technical incompetence about a decade ago, and it was a CASA bloke who showed me the FAA video, and explained that CASA was following suit. The difference is, Keating made CASA a litlgation target, and they've been in arse-covering mode ever since.

How would you handle that with Ra-aus.... register it twice with a photo from each side?

Sigh. From the Design Standards - and a little inside knowledge - a certain amount can be deduced:

ANO 95:25, the original for two-seat trainers, limited them to 40 kts stall and 1,000lb (454kg) MTOW. The Lightwing was designed sensibly, so needed a light engine to meet this ill-conceived design pseudo-standard. Then the Calair Skyfox couldn't meet the stall speed of CAO 95:55, so a fudge was added. CAO 101.55 subsequently allowed 1,200lb (540 kg) MTOW (and an almost sane stall speed of 45kts), so it seems the Lightwing was pushed out to its then structural limit at 480kg*. Subsequently a tiny bit of bent tin (aluminium) was added, and the massive(?) weight of an 80hp 912, and the structure and performance then met the design standard at 540kg. The foward fuse & engine mount structure analyses were checked, and a 99hp 912 was stuck in at least one under an EO. Now LSA allows 600kg (and a piffling 300 fpm MROC), so AL know which airframes can safely go up to 600kg MTOW (probably with no other limits changed). The NEW LSA GR-912 is, like a Cherokee Arrow to a Cherokee 140, an evolutionary step.

* This weight may have come from applying the Skyfox fudge to the Lightwing under 95:55.

Oh ok...good question...not sure which is the most authoritative there...should be interesting if I ever get ramp checked. CASA may make me amend my aircraft placard to match the manual ?? !..............Maj....

.....had Flim Tannery bolting for the door screaming...."Pollution, massive pollution, save the environment, save the.....

Probabily not at all...the 914 is the 80 HP (low compression) with a turbo attached...same case as the 80 HP......the 115 HP is achieved with 35 HP produced at the top end............Maj.....

No because we are supposed to be affordable flying not GA Mk2.

Them there bolts are actually quite sophisticated - brittleness is the enemy of high-strength alloys, and various process stages - the original alloying, forging, forming, plating, and any straightening - can predispose a bolt to failure, or simply increase its sensitivity to over-torquing. I wonder how much the bolt size increased from the 80-hp 912 to the 914?

Magnetos may be reliable and they may be low tech, but they have been responsible for as many engine failures as anything else machanical. I would rate them as less reliable than the valve train or the carburettor.

I do like the clean up on the engine cowl, that should be good for some extra knots. A three blade prop is the way to go. As I said before the full view doors are a winner but from memory can't be open in flight like the original ones. With the prop further fwd stability in all axis should be enhanced. The Lightwing needs to be bought up into the 90 kt cruise range, the proper wing change would do it....not sure if they have done it on this one. This paint job is not that complimentary either..........but nice to see another new model emerge........Maj.......

....Nobu stepped up and shoved two fingers down the Bored members throat to try and loosen the obstruction"Erky perky" wailed Turdbro, "you dont know where those fingers have been?" he said

 

"Aaaah so, you cast asplertions on my ruse of fingrers" replied Nobu

 

"My fingrers have onry bin rused for........

[ATTACH=full]29011[/ATTACH]

Bill was guided by Bruhn, and Howie was - to some degree - guided by Bill, so all the HW Lightwings represent an intersection of engineering conservatism and practical useability. I am not so much a fan of the long nose, because in the balked landing case such a prop position has a significant deleterious effect on pitch stability - if an aeroplane has the tailfeathers to handle it, it's less efficient than it would be without the hose nose. By eye, and from my limited GR-912T flying, the Lightwing should handle it...

[ATTACH=full]29001[/ATTACH] [ATTACH=full]29002[/ATTACH] [ATTACH=full]29003[/ATTACH] Well almost done .