Light Sport Aircraft concept

I prefer the canard configuration, for many reasons I won't go into here. I was thinking about how to make a canard fly slow enough to meet the Light Sport Aircraft stall speed limits. Then it occurred to me, that the genius Burt Rutan had already designed such an aircraft. This is the Solitaire sailplane, with a modified and enlarged fuselage, to accept a pusher rotary-powered ducted fan, and a tricycle landing gear. The duct would perform the function of vertical stabilizer, it would have rudders in the trailing edge. Wing and canard structure may have to be beefed-up to handle the increased gross weight, up to the LSA limit. If anyone has an interest in helping develop this aircraft, please contact me.

It flies! (in X-Plane)

Joseph Sales provided this good information:

There are a couple of good ideas already out there. One is the Ligeti Stratos with a ducted fan. Go see the web site:

http://users.skynet.be/nestofdragons/stratos.htm

Rutan designed the Lotus Microlight. For this go see: http://www.lotusespritworld.co.uk/EHistory/glassfibre.html for a picture at the bottom of this page.

Also see for a bit more background. About that site...do you know if Eippert ever produced the thing or a kit? Another site says this little bird weighed 300 lbs. and was called the Lotus Model 91 and marketed in Britain by Lotus. This differs from the previous web site that says a company called Eippert marketed the thing.

I have not seen specs for the Lotus Microlight but a 25 HP engine can't drive a very big plane. It should be easy to put a ducted fan on it.

The first web site is the only representation I've been able to find. Either the Lotus people or Rutan's outfit ought to be able to provide some specs. I sure would like to see them if you get a source.

I think the Ligeti Stratos is a neat, very compact little bird and the prototype had a 24 HP three cylinder two cycle engine. The designer killed himself in the first production version and his son is building another one by reverse engineering the prototype. Unfortunately there are no plans available, to my knowledge. I've been considering reverse engineering this one myself but with something like a 28 HP Kohler V-twin with fuel enjection.

Either of these ought to be easier to do than redesign Rutan's powered sailplane.

Joseph Sales

My comments: Yes, I've seen the Ligeti Stratos before. Looks good. The box connection between the wings should result in strong, light structure. I wonder a bit about the aerodynamics of it. The "canard" has a lot of sweep. In contrast, the Rutan canards have a straight canard (except the Starship) and have a swept main wing, one reason for which is to get the winglets/vertical stabilizers farther aft.

This is the first I've heard of the Lotus Microlight designed by Burt Rutan. Not a very well known design, but one that looks very promising for a LSA.

Bruce Layne found some more information on the Lotus Microlight:

The Lotus Microlight was apparently a technical success, but a marketing failure. Burt designed it (his model #91) for Lotus, and the business arrangements went badly. Burt was sued over this design. I think the case was dropped. Colin Chapman was the Lotus visionary who championed the Microlight, but he died the day RAF declared the prototype ready for first flight. I found the following online post:

Shortly after he died in December 1982 at the early age of 54, Colin Chapman's Microlight, the Bert Rutan designed Scaled Composites 97-M, built by Scaled Composites Inc, arrived at the Group Lotus airfield at Hethel in Norfolk, was assembled and flown for the first time in August 1983, registered G-MMLC. It was planned to have a Lotus engine, and I understand that this was being developed by Tony Rudd who was a senior figure at Lotus at the time.

The aircraft was returned to the USA in 1988, and was I understand put into production by the company Eippert, who are no longer trading.

It is an interesting "what might have been" which I would dearly love to know more about. Does anyone out there know of any published material that would provide more information, or do you yourself perhaps know the story, or part of the story, yourself - or know someone who does?

There is a photo of it in Gerard Crombac's book "Colin Chapman - The Man and his Cars" on page 348. It is a side by side two seater, with swept back wing and canard foreplane, and of course a pusher propeller behind the cockpit.

Peter Ross, Falmouth, Cornwall

Bruce also writes: And check out this link for several other great pictures and Lotus articles.

"I'll now try to produce a potted history of the microlight... incidentally, the late Hugh Haskell's book "Colin Chapman - Lotus Engineering" is full of good stuff about cars, boats (including Clive Chapman's racing monohulls..), aircraft, and even furniture. The story about the flying saucer was considered too wacky...

Rumour has it that in the very early days of board-sailing someone suggested to the OLD Man that he should get into the manufacture of said boards - "no, it'll never catch on" he is reputed to have said.

So when ultralights/microlights began to appear on the scene, and with his love of flying to encourage him, Chapman "got into" microlights very fast and deeply. I think it was Summer 1980 when we got taught to fly behind the Chapman house in a Double Eagle, driven by two two-stroke paint stirrer engines.... it hardly flew, and bits fell off every hour or so. ACBC believed that Lotus composites know-how could be applied to build a "proper" aircraft that still met ultralight rules (and hence would be cheap and easy to fly i.e. very attractive to buyers). He commissioned Burt Rutan of Mojave, Ca to design a new type of microlight, based on Rutan's love of composites, efficiency, and the use of the "canard" wing layout for which Rutan is famous. (He designed Voyager, which flew round the world, and the Starship, which has nearly broken Beech). At the same time, Lotus were set the task of designing a small lightweight 4-stroke aero engine, which would fix the inherent two-stroke problems of noise and gas-guzzling. (Ian Doble, the engineer given the task, went on the lead the LT5 engine programme, the Elan programme, and has just finished the Vector in Florida.)

First, the aircraft - two-seat side by side enclosed cockpit, retract front wheel, unique design. Tragically and ironically, the maiden flight was December 16, 1982 - the day ACBC passed away. Trials continued with a little Italian two-stroke engine, to the end of the proof-of-concept phase. I watched some test flights in Mojave, and was totally impressed with the machine. Next time I saw it was August 1983, when it arrived in a crate at Hethel - two days before the Open Day Mike Causer referred to. We assembled it on Friday and Saturday, I taxied in daylight on Saturday afternoon, and "accidentally" hopped in the dusk. My first proper flight was Sunday morning, with the demo flight in the afternoon for the crowds. It was exciting, terrifying, and very emotional for me.

(Yes, it did appear at a Brands Hatch CTL event, but I thought that was `84?)

We wanted to build a business for it, and sought company backing to continue alone. When that wasn't approved, we went looking for partners. We eventually teamed up with Eipper (a big ultralight builder in those days) to distribute it in the USA, and Malcolm Lawrence's Aviation Composites in UK and Europe. We originally planned to build the basic structure, with AC to finish and distribute it. We then decided that the materials (epoxy glass) and the quality control techniques were not part of our core business, and AC agreed to take over the development and build, with the help of Specialised Mouldings (well known in motorsport). As we were struggling to cope with the aftermath of ACBC's death, AC's move into taking over the whole project lock, stock and barrel, was a godsend. They built at least one more prototype, with various modifications from the Rutan design, showed it and test-flew it. Sadly, their prototype apparently exhibited some less-than-attractive characteristics, and they sued Rutan. The case dragged on (way beyond Lotus being taken over by GM in `86) and eventually was either dropped or Rutan won - I can't remember which. The backers disappeared, and AC went into liquidation. I don't know where the Rutan prototype is, but I'd love to find it again... it flew beautifully - just what Chapman would've wanted.

The engine was a brilliant concept - a modular monobloc design (crankcase half, barrel and head cast in one piece) which could be built as a two- or four-cylinder (25 or 50 hp). To keep the weight down, the castings were intricate with minimal fixings and parts count. The prop drive came off the camshaft to use the inherent 2:1 reduction drive - brilliant thinking! (You need a big prop turning slow for efficiency, and a small engine turning fast for good fuel economy). However, we didn't have the sophisticated CAE systems we have now, and we experienced severe torsional vibration problems.

After slogging on, we got up to 150 hour durability (way below our hoped-for 1000 hour goal) about the same time GM spotted we had a connection with the aircraft business...The engine project was closed down very fast to prevent any possibility of aviation-sized product liability lawsuits. Sad, because the world is still crying out for a light, cheap, four-stroke aero-engine. The Rotax is nearly there, but... even Porsche failed with the PFM aero-engine based on the 911 motor!

We have one of the 4-cyl engines on display at the factory - it is still a gem and sits proudly alongside the LT5 engine and the 1.5 litre compound-supercharged F1 engine we were doing about the same time..... what would it be like if we used our second new Cray to support the analysis today?

We were close to supplying the engine for use in target and reconnaissance drones (some flight testing was carried out) but it didn't happen.

TO KCLAIBORNE: yes, the Lotus microlight was a dream - for aircraft spotters it had a pointy nose, little wing at the front, and the prop at the back behind the big wing - and it was FAST! No, we didn't get to Paradise/Hawaii on any durability flights, sadly...

Regards,

Patrick Peal, Head of Communications, Lotus Cars Ltd."

Here are several images from that site:

This article is more about the new Lotus sports car, but does mention the previous Rutan association with Lotus and the "Elsie".

Marv Reese sent me his links to his RC Model of the Ligetti Stratos:

http://users.mo-net.com/shirl/LigetiStory.htm

http://users.mo-net.com/shirl/StratosTech.html

http://users.mo-net.com/shirl/StratosFly.html

http://users.mo-net.com/shirl/Design.html

As usual, Paul Lamar has some very good ideas. http://www.rotaryeng.net/roadable.html

Here is his latest idea for roadable canard. If it could be made light enough it might also qualify for LSA. An intriguing idea even if it must be in the experimental category. Power is taken from the front of the engine to drive the main wheels in car mode, from the rear to drive the prop. The wheels are driven during takeoff to get the plane up to speed faster, shortening the takeoff roll.

There is the Goldwing ultralight, no longer in production. Stall speed 25 mph, cruise 55 mph, vne 70 mph. Empty weight 240 lbs, gross 510 lbs. A little too small to be a useful LSA but it does show that a small, light and low stall speed canard can be built.

12-31-2006

Cliff Cady writes:

My suggestion would be a Light Sport based on the VariEze design.

Light Sport Requirements VariEze related specs. (from owners manual) Max Gross Wt 1320 lbs 1110 lbs could be bumped up Max Stall 45 Kts 46-49 knots, 35kts accelerate stall Max Speed 120 Kts 120 Kts maneuvering speed, climb prop would help Landing gear Fixed landing gear Nose gear could be fixed to NG30 or only retractable for parking

Here is a site with great visual of a modified Varieze. Gets you inspired. http://members.cox.net/sejii/ve.htm

Possible modifications:

Wings could be made removable like was done with the Jiran wings. Example pictures at http://michaeltdrew.com/photo4.html This would allow for trailering and also allow easy testing of longer wings if it was needed to conform to Light Sport requirements. The removable sailplane type wings would be a plus. If nothing else it would take up less hangar space. I have seen the way the Europa wings remove and it is fast. They pull a couple of pins per wing and pull the wing out. The controls connect thru matching plates that come together.

Roncz canard to eliminate rain problems and possibly lower stall. It has been done by a varieze owner.

"My VE with the GU Canard exhibited a high nose down pitch tendency in rain that took lots of stick pressure to hold level, estimate 30 pounds. The lift is higher on the Roncz which could lead to wing stall so the solution is to reduce the lift by decreasing area through span. I retro fitted a 118 inch Roncz to my VE 5 years ago and it changed the whole personality of the airplane for the better. No pitch change in rain, less pitch sensitivity, convergent stick free pitch stability, 4 Kts more speed and a more stable feel in pitch axis, overall a very worth while improvement. Nigel Field Subaru Vari-Eze (Suze)"

Wider fuselage at least as wide as the Long-Ez to fit larger people. Drag reduction [increase] would help keep the top speed down.

Larger tires for better grass taxi options. Extra drag would help limit top speed to fit Light Sport limit.

Baggage Pods could be used to help keep top speed down while adding useful baggage space. Good thing is it's also a tested option.

Engines: Light weight like

Jabiru 2200 http://www.usjabiru.com/jabiru_2200a.htm

Or VW engines (not my choice) http://www.aeroconversions.com/

Or Verner 133 http://www.centralfloridaflyers.com/

Or HKS 700 http://www.hpower-ltd.com/pages/specifications.htm

A ducted fan option would help keep the top speed down.

Possible Varieze derivative advantages:

Based on a known design and construction methods.

Parts pretty easy to make and some still available.

The smaller size would make building easier. http://varieze.homestead.com/

Simple design.

It still looks good!

My Comments: Back when I first started thinking about a LSA Canard, the first thing that came to mind was the Vari-EZ because it's in the right weight class. Then I hit upon the Solitaire-based concept. When I think of Vari-EZ, I think of a plane that lands even hotter than the Long-EZ because of the small highly swept wing.

I think a Vari-EZ could be modified to work, probably by increasing the chord on the canard and removing some sweep from the main wings. It would then start to look more like the Lotus Microlight.

And my first engine preference for any airplane would be the rotary. A direct-drive ducted two-rotor with aluminum side plates would surely work very well as a LSA powerplant.

Canard LSA Links added as I come across them:

These guys advertise a derated Light Sport Aircraft version: http://www.freebirdextreme.com

A French Canard design, the weight is ok but the stall speed appears to be too high: http://www.junqua-aircraft.com/

A beautiful Canard design from Germany, claims a stall speed of 40 mph and that it meets LSA requirements. Available as a kit: http://www.rmtaviation.com/

Youtube video link http://www.youtube.com/watch?v=oT7XEpy83FE

A Scottish design

Please report any LSA canard links to me by email and I will add them.

NOT Canards but Interesting planes that might make fun LSA:

I wonder if the Rohr 2-175 might make a good Light Sport Aircraft. I'm unfamiliar with the stall characteristics of delta wings, and the engine-out glide may not be very good.

Stefan Têsny from Poland sent me this interesting concept plane.

Here is his website: http://druidpop.ovh.org/sjet.htm

A similar concept, Ion Aircraft

Oliver Bozic from Boznia-Herzegovina sent me this design, one way to incorporate a ducted fan pusher into a conventional planform.

Back in 1998, I called my aircraft "Duckt", a combination of "Duck" (English for "Canard") and "Duct". I just found out by internet search there is another aircraft out there with the same name:

http://www.aquaduckt.co.nz/eider_duckt_specifications.htm

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