Ligeti Stratos

[Guest High Plains Drifter]

Just going thru old storage boxs for a dump run and came across Sky Sports magazine, Spring 86, No 1 issue.

 

Centre fold liftout is a first in the series of frameable photographs of Australian designed aircraft picture of a LGT - Stratos. It is one wild looking machine.

 

Claims of 90kt cruise on 15kW (whats 15kW in real terms? i.e. ponies)

 

I havnt seen any of these aircraft around and was wondering what happened to it?

 

.

 

 

[Guest Macnoz]

all the info here

 

http://www.ligetistratos.com/concept.htm

 

 

[Guest palexxxx]

Claims of 90kt cruise on 15kW (whats 15kW in real terms? i.e. ponies)/quote]

15kW is 20 HP

[Guest High Plains Drifter]

Thanks for that Macnoz and palexxxx.

 

Makes you think. An 80 hp 912 Rotax uses about 15 litres an hour at cruise, so a 20 hp engine would use say 4 litres per hour ?

 

....90 knots at 4 litres per hour !!!

 

.

 

 

[planedriver]

Funny this post should come up today, only last night I was looking at several web-sites regarding the Ligetti Stratos. It looks a mean little machine so different from the rest in the croud, but sadly came to grief when stalled on finals after a short flight after numerous modifications. Apparently the son who is an acomplished aeronautical engineer is working on a second generation model. It will be very interesting to see what the outcome is.

 

There is quite a bit of info at this site http://www.ligetistratos.com/history_story.htm which you may like to check out, if you have not done so already.

 

Rgds Alan

 

 

[Guest asic45]

The original Stratos, in which the pilot came to grief, is currently being refurbished at the Ballarat Aviation Museum where it will be put on static display.

 

 

[planedriver]

It's sad that advancement is often made by people with a vision, who pay the ultimate price before all the bugs are ironed out.This man created something he believed in, and one day it may still become reality through the interest and admiration of others in his work, who may carry on where he left off.

 

I'm sure many of us here would like a good reliable means of flying from A to B safely, with the sort of economy that the design envisaged.

 

 

[youngmic]

Scott Winton (?) was another local cutting edge designer around the same time. A young bloke who died prematurely in one of his own designs.

 

Set some remarkable records for endurance and altitude if I remember rightly.

 

M

 

 

[planedriver]

Scott was a lovely young guy, and when I met him we discussed how the Facet Opal looked so similar to control-line combat model aircraft that I used to fly many moons ago, which were so manouverable. His demise is a sad loss.

 

One thing that did stick in my mind was that the Ultrabat that he was working on (the forerunner to the Saphire) had a problem with the aluminium boom cracking where it met the fibreglass fairing at the back of the fuselage. this problem he must have fortunately overcome.

 

 

[youngmic]

I didn't realise the Ultrabat was one of his designs. If I remember correctly it was a bold venture to build an ultralight design to compete in the unlimited aerobatic class.

 

Amazing! he certainly was out there, such a huge loss. If he'd been born in the US he could have well become another Jim Bede or Burt Rutan.

 

M

 

 

[Guest High Plains Drifter]

Having a further read of Sky Sports Australia No 1, in an article on Mangalore 1986 there is a reference to Scott Winton (and a picture)

 

....Australite Pty Ltd commissioned engineer Graeme Swanell and fibreglass craftsman Scott Winton to build a competitive, cheap aerobatic aircraft from the Sapphire concept. The resulting Ultrabat has a permit to fly as a developmental aircraft per ANO 101.31....

 

While it appears it was not a full Winton design as such, I guess there was probably a bit of reverse engineering involved.

 

There used to be an Ultrabat in Hemples shed at AF, looked to be an interesting aircraft...... anybody got a flight review of the Ultrabat ?

 

.

 

 

 

[djpacro]

I did some flying in an Ultrabat and was very impressed with it. Straining the memory to offer much comment off the cuff except to state that it was competitive at Advanced category competition level back then.

 

As this thread is about Stratos I should add - Ron is very keen on succeeding with his project and I wish him well with it.

 

 

[Guest ozzie]

The Ultrabat (vh ant) that was flown by George Markey was kept in the hanger were i used to work at Camden. George took the design to the States were it was intended to go into full production. It competed in and won several aerobatitic competitions and was i belive banned i think the Pitts pilots complained about it.. I never had the chance to fly it but i observed it on a few occassions. it was very agile and not for the novice.

 

It was built by Scott to George's perfomance wants. I only ever saw the one aircraft.

 

pretty sure that the Sapphire came first. last i heard of 'ant' it had just charged thru a crowd of people at an airshow somewhere.

 

The Stratos was/is a great looking aircraft. i read a report from a wittness that the pilot was actually doing a low high speed pass down the runway . it was seen to hit a some turbulance and the aircraft tucked and tumbled and hit the ground. i have never heard of it stalling in.

 

ozzie

 

 

[djpacro]

I was reminded that the late Alan Hannah competed at the national aerobatic championships at Bendigo in 1987 flying the Ultrabat which was when I flew it. As I stated I would've been happy to compete in Advanced in it, wasn't sure about it at Unlimited level but one of my colleagues (flying a Pitts in Unlimited) said he'd do it. The only adverse comment that I heard was about the shape as presented to the judges - would take a bit of education. George was very pleased with the response he got from "serious" aerobatic pilots. Some notes I found from some-one else (complete with original typos):

 

rod f. says "it snap rolls and lomcavaks better than any aeroplane Ihave ever flown, loops well, stall turns on a dime, rolls ok and

flies inverted well. The machine actually spins inverted better than

 

it does upright because of the aerodynamics assciated with the

 

engine fairing etc. And flat spins inverted are a real buzz with

 

full throttle, and when you need to recover it is instantanous as

 

there is not much inetia at 200kg. For an areoplane with 50hp it is

 

pretty hard to beat"

Last I heard, only a few years ago, it was alive and well in Mt Gambier. I see that the website is still there.

http://groups.msn.com/ultrabat

 

Perhaps I should've started a new thread but as I'm still here, another comment related to the Stratos. I got involved a little with a technical assessment after the accident. It is not easy developing a new aircraft, let alone one with a unique configuration. Ron should update his online CV, he's moved on since then.

 

 

[Guest asic45]

Stratos

 

A couple of pics of the restored Stratos which has been put on display at the Ballarat Aviation Museum. For anybody interested, the museum is open from 1pm to 5pm on weekends, or by appointment.

 

 

 

 

 

[planedriver]

Good to see the photos asic45. Thanks for posting them.

 

Rgds Alan

 

 

[pylon500]

From my limited exposure to these two aircraft, I offer a few minor corrections....

 

The original Stratos, in which the pilot came to grief

Actually it was the MK-2 (production) version that crashed.

Stories say that it entered a deep stall, tumbled and went into the ground flat, inverted, killing the pilot via head injuries.

 

The airframe was not damaged badly, and was restored, which is the aircraft shown in the last photo's.

 

Remember, this is the MK2, the original prototype was/is still airworthy, and still owned by the Ligeti family.

 

Aerodynamicist discussions point to a change in wing dihedral/anhedral layout from the original which led to greater 'blanketing' of the rear wing during the stall that induced the deep stall.

 

Ultrabat that he was working on (the forerunner to the Saphire)

As corrected by Ozzie, the UltraBat was actually based on the Sapphire.

The story goes that George had a Sapphire, and was busted doing aero's in it (at the time I think he also owned a Victa, which he aerobatted) so he funded Swanell and Scott to build a fully aerobatic Sapphire.

 

The UltraBat depicted in the link http://groups.msn.com/ultrabat is actually one of about four (I think) that were produced in the U.S. until George and the Americans could no longer see eye to eye. i_dunno

 

The original (only Australian) UltraBat never had a canopy, and was powered by a Rotax 532, a range of motors were used in the U.S. versions.

 

Arthur.

 

 

[jcamp]

Mick Parer had a video of a bad crash he had, became airborne and veered off into a cloud of dust/bits. IIRC it was a Stratos, anyone have any info.

 

 

[ronsky]

Mick Parer crash

 

A friend sent me a link to this forum I am writing to elaborate on what happened

 

After my father Charles Ligeti crashed the second “highly modified†Stratos claiming his life, the company decided to make another aircraft, keeping the bad aerodynamic changes to the aircraft then adding more changes. The aileron linkage setup was changed causing increased aero-elasticity in the ailerons. The duct on the original Stratos ran a 3/16†tip gap between the prop and duct. There was a ½†gap on this aircraft. Due to the nature of ducted fans and how they work, would cause at least a 20% reduction in thrust on an already underpowered design. The following occured.

 

The aircraft takes off at Mangalore airport flying level with the runway, altitude of about 2 meters, right wing noticeably lower than the left against the horizon. The aircraft slowly straightens wings level, with the engine at full throttle the aircraft barely gains altitude, running out of runway Mick turns right, mid turn - wing angle of around 30 deg the sound of the engine cuts out, immediately the aircraft sideslips and hits the ground, after the right wingtip strikes the ground it rotates the aircraft around to finally rest. Aircraft noticeably damaged, relatively intact but unfixable to test. (Mick Parer later reporting the ineffectiveness of the ailerons and lack of power).

 

If requested I can elaborate on the “highly modified†aerodynamics of the second Stratos, specifications of the original Stratos that flew successfully and details of a new aircraft.

 

 

[Guest brentc]

Thanks for the update Ron.

 

Found this today when trolling on my day off. It has a few minor similarities in sytling to the Stratos.

 

http://www.eggenfellneraircraft.com/E2B.htm

 

 

[ronsky]

That looks like a nice design. I always liked flying wings from the Horten designs to the B2 and the new Boeing BWB experiments. Northrop had a number of designs. I know one had a nasty stall that sadly killed the test pilot. If i remember correctly they named “Edwards†airforce base after him. If done correctly they can fly well and be super efficient. I believe the Boeing design tries to ease the stalling by using the forward fuselage as a lifting body, giving a canard stalling effect, be curious to see the results. If the EGGENFELLNER wing sweep and angle of incidence is done right it could be a real go-er!

 

 

[pylon500]

I've always been a fan of radically shaped aircraft, but I do tend to believe there are limits, and I think that Eggenfellner mini delta thing would be impractical.

 

I have modelled similar shapes in X-Plane, which were virtually unflyable.

 

Back to the Stratos...

 

So Ron, what's the status of the original prototype?

 

Could the MK II control system be retrofitted to the original? (after watching the 'Beyond 2000' clip, I could see there was an inertia coupling problem with the stick/pitch layout, which looked to have been solved in the MK II)

 

Was the 'Deep Stall' analogy the actual cause of the crash?

 

It would be good to see a Stratos back in the air....

 

Arthur.

 

 

[ronsky]

I agree I think there are limits to designs as well, That’s interesting the website changed since i first looked at it. The pictures at the bottom are of a swept flying wing, the delta is new. I try not to critique other designs at concept stage because they usually morph – ironing out the bugs after their inception, stall speed and elevator effectiveness are two concerns on the first design. There are flying wings that work well. Hopefully these guys will do their homework, If they do it properly they can get an efficient flyer - be it modified a few times.

 

I’m weary of Xplane it is a good analysis tool but, I don’t trust it on non- conventional designs for a number of reasons. I lean towards scale R/C models, if you correctly modify airfoils etc for Reynolds number and use a similar power loading, it can show a great deal more, Rutan did most of his work this way. I know guys who professionally model aerodynamics. They use industry standard programs and they still don’t fully trust them. I know of a few issues.

 

The original Stratos is an airworthy reference piece I use to check against, it also holds a sentimental value to the family, maybe one day we might put it in a museum or something.

 

I’m confused? I double checked with one of my aerodynamics books, inertia coupling is a multi axis gyration that occurs on supersonic aircraft.

 

Charles would dive the Stratos to Vne at 270Km/H where the Vne limit was due to engine over-speeding. He did not report any stability problems. Compressibility effects don't occur at that speed. There was an inertia effect on the elevator when hitting turbulence, my father mentioned that he had to mass balance the elevator to get proper stick free stability by neutralising elevator inertia. Stick fixed stability was reported to be fine. He balanced the MKII elevator, he didn’t have time to go back and mass balance the prototype elevator.

 

I would not use the control surface layout of the MKII because of the elevator for stalling reasons. I am opting to use the prototype control surface setup for various reasons, with a mass balance at least on the elevator.

 

Yep the MKII did stall at a far greater magnitude then what the prototype would stall at low air speed, hence why it caught my father off guard, i remember he was also below 500ft as per CAA regulations at the time.

 

 

[pylon500]

Yes, your father is and will be missed.

 

The 'inertia' coupling I was referring to was with regard to the stick and the way it could use the weight of your hand to induce an over-controlling PIO.

 

I guess I missed the mass weighting of the stick to dampen the problem.

 

The MK II parallelogram system would have required less mass balancing, and be easier to hold.

 

The pictures at the bottom are of a swept flying wing

These things can catch us, actually when I scrolled down and saw the flying wing, I thought 'That's a better looking layout', stick with that.

Great to have you on board.

 

Arthur.

 

 

[ronsky]

Thanks Arthur, that is really nice of you to say. No need to be sorry it’s just the way it panned out, we all meet up again in time

 

Yeah, you are right that would occur, If the stick axis is placed back to where the hand is, it should alleviate any PIO. Charles put a side stick control in to the MKII, but I’m not sure how much space he had around the control hand. I might visit that.

 

 

Thanks for the welcome

 

Ron