The Lightwing Mystery

[Yenn]

The Lightwing in my opinion is more like the old GA aircraft. An honest aeroplane and good to fly. Some of the new RAAus types are more like GA than GA planes are if you get my meaning. Most of the GA fleet is about 40 plus years old and looking a bit ragged, plus they don't perform as well as the plastic fantastics.

 

 

[Guest nunans]

Interesting....I've found that most Lightwings prefer to be flown at their rearmost CofG, (I can hear all the experts getting ready..) which is still only at 22% on some of the earlier models.

The LSA models can run to 25% and will three point better, but then you have to really be ready with the rudder because of the main gear dynamics.

 

Rearward CofG's will help to reduce induced trim drag when cruising but can lead to pitch sensitivity in short coupled aircraft.

 

Fortunately the strong pitching moment of the flatbottom section on the lightwing is countered by the reasonable amount of Decalage between the wing and tail.

 

OK, so 'Please explain...?

 

Arthur.

I flew one for the first time today (GR-912- 0692 i think) and had a bit of trouble keeping the nose up during the hold off, I was power at idle as instructed and one minute your coming over the fence at 55-60 and then you level out, before you know it you've got the stick back on the rear stop and if you're not already on the grass it drops on!! I wasn't expecting that big wing (GR) to just run out of lift like that.

 

It almost felt like trying to three point the T500 thruster I once flew,

 

So I don't know, was the c of g not far enough back and therefore I was running out of elevator authority early? or is this just the way they fly? or are you meant to get back on the drag curve and tow them in with power?

 

In my little pup the elevator has alot of throw (maybe 50deg each way) and the gaps sealed and I can pull the nose right up if need be late in the hold off and I can get the tail wheel down first at idle or if I pour some power on I can get the tail on the ground with the mains still 6" - 12" off.

 

??

 

 

[Guest Maj Millard]

Well you did a couple of things correctly nunans, the over the fence speed sounds ok, but may have been a touch too fast, you were back at idle which is correct, and you had the stick on the back stop which is also desirable at touchdown. I'm thinking you may have flared a little high and/or a little late, or let the speed decay too high above the runway.

 

Once the stick is against the back stop it's all over (or shortly going to be !) as the angle on the wing at that point is creating more drag than lift. I wouldn't consider the Lightwing hard to land at all (especially the GR), but like any aeroplane it may take a bit of practise to get the best technique down, so that you can do it the same everytime.

 

I have a GR with the optional flaps (stolen from the GA), so mine is even easier and more consistant to land. I do remember the standard wing likes to float, (especially if your a bit fast) and will just sit a couple of feet above the runway until the wing slows down and quits. Have a look at the acerage on the belly !....it's like the space-shuttle under there !....I've done 600 hrs worth of landings in mine now, and it really is a no sweat affair.............................................................Maj...

 

 

[pylon500]

G'Day Nunans, yeah, there's a few assorted things going on there....

 

Most GR-912's tend to run nose heavy, and part of the original design philosophy was to limit the elevator travel, hoping to create a 'mush' instead of a full stall.

 

Unfortunately this mush develops into around about an 800 fpm (or higher) decent rate, not the sort of rate you want to contact the ground at !

 

Elevator gap seals here are important.

 

As a side line, I should point out that aileron gap seals are MANDATORY on a Lightwing, it flies really badly without them.

 

There is also another problem that is not spoken about much, or totally proven/disproven, that deals with the shape of the cabin roof, and the airflow it causes over the tail at high angles (flaring) of attack.

 

Depending on the fit of the gap seals and number of antennae in the cabin roof, it is suspected that during flare, airflow over the cabin prematurely separates causing a drop in elevator response as well as triggering an earlier onset of stall, ending up with your 'drop on' effect.

 

I may sound vague here about a definite tendency because, of the 9 Lightwings I've flown, only 3 of them did this noticeably, the rest were fairly docile.

 

The GR 582's are easier to flare and land (at idle) as they are lighter and have the undercarriage in the right place (it's a long thread, but I explain that statement here; http://www.recreationalflying.com/threads/the-lightwing-mystery.6696/page-2#post-235738).

 

The GR-912's with the U/C further forward prefer to be 'three pointed' as they are easy to bounce, BUT some GR-912's can be wheeled on as easily as the two strokes??

 

All my landings are based on dead idle, full glide approaches, anything is easier to land with a bit of power, but one day you may not have it.......

 

 

[Phil Perry]

Lookout Deskpilot! Statistics prove there'll always be a spike in baby births 9 months after a power outage....

That's all very wel to suggest Wayne, and I just Luuurve statistics. . . . BUT. . . . how the heck do I get away from the Missus and get down to the girlfriend's house to make a baby in the dark ???????????????

 

 

[Phil Perry]

Ahh, Lightwings.......

 

Flippin 'Eck Arthur,

 

That was a brilliant post, We don't really have anything in the UK to compare with the lightwing, we had the thrusters, ( and still do) and the MW series of stick insect aircraft ( very popular for low cost flight ) and the Rans series are very popular also, but there really isn't anything like that Lightwing. Sure we have the Denny Kitfox, lots of variants of that one, some are GA if the wing loading is less than 25Kilos per square metre, the marques are 2 to 4 as far as I'm aware, the Marque 4 is GA, with a "Cessna Style" one piece steel main gear arrangement, a Rotax 912 and bugger all luggage space. this is their only downfall really, although on of ours ( Mk 3 - G-PPPP ) has what looks like a missile or drop tank slung on the underside of the fuselage for stuffing your tents and other rubbish into. Some of the early Rans series were supplied in the tailwheel config, but these were unpopular with low time appliance operators ( and unedifficated instructors ) who didn't want to REALLY LEARN how to fly a proper aeroplane. Trike undercart was adopted for nearly everything on the market many years ago and that I think is a shame.

 

One of my UK forum friends just bought an ESCAPADE which is a 912 powered rip off of a Kitfox / eurofox side by side seating trike jobbie, and immediately converted it to tailwheel.

 

I am justly proud of him, he hasn't ground looped it yet ! I toasted him last week with Champagne and Vegemite ( on toast ). Why oh Why is Vegemite so hard to buy in the UK ?? I have to go into fancy stores where, if you ask the cost - you obviously can't afford it.

 

I'm coming back to OZ in 2014, and as long as I'm still breathing, I want to have good look at what's going on and what's being flown there. . . . and providing I can lose some weight. . . I might even try a flight or three. . . .

 

Phil

 

 

[Guest Crezzi]

some are GA if the wing loading is less than 25Kilos per square metre

I think you mean they are GA if the wing loading is greater than 25kg/m2 ?

 

Cheers

 

John

 

 

[Guest Maj Millard]

Arthur, All good stuff there. I can comfirm that the later GA with gear foward, do prefer to be three-pointed, and that's generally what I do with mine. You can get a wheeler out of it with a bit of power, but you need to work a bit also. Because mine has flaps (which I generally use for landing), the bounce tendency if you stuff it up, can be even worse !. Although with the great throttle response of the 912, it is easy to pick it off the top of a bounce if you have to, for a go around and another try.

 

I've also flown a lot of early LWs including 032 the first production one, and yes I would agree they tend to be more 'enjoyable ?' with the earlier gear.

 

And whilst we are on the subject...one of the most delightfull aircraft to land that I have encountered is a very early production Slepcev Storch with an 80hp 912, and rag-wings vs the later all metal wings.. Just loves to be wheel-landed every time !... The later 100hp metal winged SS4 Storch, (heavier) is just not the same, although they do land very nicely also compared to many other aircraft.

 

Very interesting what you say Re: air over the cabin...could well be a blanking effect on the elevator at high aoa. Would be interesting to try some Vgs on the roof top to see if this would improve airflow down onto the tail ??.................................................cheers,....Maj...

 

 

[Guest Maj Millard]

Yes Yenn, I do remember Noel Patrick, a nice gentleman who handed 032 over to us when we picked it up fron the Old Station Flying-club hangar at Old Station. I ferried her to Townsville via Hedlow and Proserpine (R532 at that time), and a very pleasant flight also as I recall, except for one ignition wanting to mysteriously 'drop out', usually right after take-off !....in fact druing the very first take off out of Old Station I put her back on the strip from 200 ft after the first and very unexpected ign 'drop-out'. Revs would go from a healthy 6700 back down to 6000 all of a sudden, and then come back just as mysteriously about 20 seconds later. I was quite used to this by the time I got her to Townsville !!...in fact i was fairly used to it by Hedlow !!...

 

I'll never forget the first time I saw her !....I was dragged over to the dark hangar late one night during the Old Station fly-in, after several beers to 'inspect' her by a potential buyer. By the light of torches only we looked her over in a resplendant white/maroon paint-job, and I saw enough to give the thumbs up, as she was a great buy for the asking price. We were back there the following weekend to pick her up..........................Maj...

 

 

[Phil Perry]

I think you mean they are GA if the wing loading is greater than 25kg/m2 ?Cheers

 

John

Course I do John, for Chrissake, whaddyer think I is ? a bleeding airodi aerody earohdie eurody . . . I just fly the damn things,. . . I have no idea what makes 'em work ???????????????????