Waiex. The excellence of B series

Un Waiex-B


By Paul Dye

(Translation by L. Pavese)

I had already understood that there was something different when I approached the airplane.

Aside from the fact that it was painted red, instead of Sonex's standard yellow, the new Waiex Model B (which is also available in the "straight" or cruciform-tailed version) looked just a bit bigger.

Not much, only where it matters most: in the spaciousness of the cabin, in the position where you sit and, in front, where the engine attaches.

The wider muzzle is also supplied with a wider fireproof bulkhead and a wider canopy: all elements that suggest an opportunity for those who are always looking for more power.

And when was the last time you met a driver who wanted less?

The Sonex range of simple and light aircraft consists of a series of different models, but which all refer to the original Sonex two-seater with side-by-side seats, equipped with the AeroVee engine, a derivative of the now classic Volkswagen engine produced by AeroConversions, a sister company of Sonex. Of very simple construction, and characterized by tear riveting and the absence of composite curvature aluminum surfaces, the original Sonex could be purchased as a kit for quick assembly, for traditional construction or simply as a set of drawings, with all the parts more complicated available at Sonex.

The original aircraft was available with conventional empennage (Sonex), or with the Y-tail (Waiex, which is pronounced Uàiex, because the Y in English is pronounced uài; that is, with the butterfly empennage); and both versions were available with bicycle trolley (rear tricycle) or front tricycle.

Waiex - B (above) compared to a Sonex - B (below)
with front tricycle trolley and cruciform empennages.

The current model B represents the first important update of the Sonex / Waiex project; and Sonex has been very busy selling new kits since the new model was unveiled at Sun'n Fun in April 2016 in Lakeland, Florida.

During our visit to the factory, they saw many pieces and components for the kits of the new version, and the improvements are very evident.

The first thing that catches the eye, looking at the Waiex-B, is precisely that the muzzle seems bigger, and in fact it is true.

The main modification to the fuselage consists in having eliminated the tapering of the fuselage, starting from the back of the seats up to the fireproof bulkhead. The fuselage of the original aircraft tapered about twenty centimeters (8 inches or 20.32 cm) in the space of that length, causing the flame retardant bulkhead to be narrower, and limiting the range of engines that could be housed under the hood . The new design is also an improvement because it facilitates the construction of the fuselage, as well as offering more space.

Moving on to the passenger compartment, anyone familiar with the original design will immediately notice a couple of changes. First of all, the instrument panel is higher, thus allowing the installation of modern and larger EFIS screens that could not enter the original panel. In addition, the panel is now vertical, while before it was inclined. This will probably be an advantage in reflex prevention which, at times, in the first version, designed in the era of "pressure gauges", was a problem.

The second thing that an aficionado will notice is probably the "eyelid", or anti-glare screen, which in every Sonex plane is a wide and broad structural element. In the original project the piece had three very clear planes and angles. The new screen consists of a continuously curved metal panel which should be able to be mounted very quickly.

The last significant change that they noticed, during the first inspection, is the most reclined pilot position, allowed by the redesign of the bulkhead behind the seat. Basically, the transversal element now has a step that allows you to move the upper part of the seat back a bit, allowing the pilot to be in a comfortable semi-supine position. The new seat also has a slightly different shape, due to the changes made to the crowning of the substructure; and the use of a single central control lever frees up even more space in the cockpit, giving the whole interior a large and airy appearance.

The single center bar is something that had been tried before on Sonex planes; and we liked the idea immediately. In fact, to a driver seated on the left it appears to be a lateral control lever on the right, and to the passenger it appears to be a lever mounted on the left. In both cases, it is easy to control, and frees up a lot of space between the legs, making getting in and out of the passenger compartment easier; it also allows occupants to change their position in the legs and knees in flight.

There are other refinements of the design that are more evolutionary, and generated by years of production process and by conversations with manufacturers and pilots. An example of this is the new canopy closure system, which can now be locked in a semi-open position on the ground, for better ventilation during taxiing.

As you may have noticed, we have not yet talked about the flap lever, present in most Sonex. The reason is that the new model B has an electric actuator, with a rocker switch in the panel. The control is precise and the angle of the flaps is continuously variable; and now it is impossible to exchange the lever of the hyperstainers for the brake lever, as happened to many Sonex pilots at the beginning.

On the flight with the B.

The prototype of the B model is a Waiex two-wheeled trolley (rear tricycle), equipped with an AeroVee turbocharged engine, which produces around 100 hp (74.57 kW or 101 hp). When we flew it, the plane had just finished the first phase (Phase 1) of the tests, and had only been flown by Joe Norris. Norris is the test driver of the company and responsible for the instruction for the "steps".

In fact, our first flight was also the first time that the plane flew with two people on board; and therefore gave Norris the opportunity to prove how the plane would have behaved with pilots willing to carry a passenger.

The cockpit was comfortable even with the two of us on board, both having an average build width (which usually constitutes the limit on small airplanes with passenger seats placed side by side) .Norris and I also enjoyed ample space for head, under the large hood with lateral opening.

I had to use a cushion behind my back to be able to reach the pedals, since the seat and pedal board cannot be adjusted. Visibility above and around the muzzle is good.

The plane is equipped with a single lateral brake lever, located under the throttle lever. The airplane taxiing with the throttle just a wire above the minimum, so you can set the power and then taxi by modulating the speed using the brakes (although the correct technique is to bring the throttle to the minimum before operating the brakes ndt).

It steers with the pedal, thanks to the tail wheel which is not free-rotating, and is attached to the directional. You have to be careful and anticipate the curves, to avoid getting into a canton from which you cannot get out (because the brakes are obviously not individual).

Some manufacturers of Sonex aircraft have modified the aircraft by equipping it with individual brakes and free-spinning wheels; therefore modification is possible if one really feels the need.

As on all Sonex, equipped with AeroVee engine, starting the engine is simple:

Fuel selector ON, on the tank.

Master: ON

Then the ignition, but operating the switch only after pushing the mixture lever forward.

The mixture lever must not be left fully open, with the engine off, otherwise petrol will escape from the body of the AeroInjector. It's something you just have to get used to. The engine starts immediately, without any particular magic, and rests on a comfortable minimum - even if it rotates "backwards", compared to most American engines - so don't be surprised.

The controls, before take-off, are simple: test the aerodynamic controls, magnets, engine indicators in the green and you are ready.

Norris gave me some reference values for the supply pressure (MP) and the speeds to follow: take-off power 40 inches, reduced to 35 inches for the climb. Ascent speed, 100 miles per hour (87 knots, 160 km / h): which are the values with which he has so far achieved the best results.

The cruise is held at around 30 inches of supply pressure, which produces 125 to 135 miles per hour (108 - 117 knots). Since the airplane has only recently left test phase 1, but is still in the expansion phase of the flight envelope, the speeds and performance values have yet to be established with certainty; so we can expect further small adjustments before the first new customers start flying.

With the turbocharged engine, the initial acceleration is better than what we experienced with the two Waiex equipped with "aspirated" engines that we tried, and the plane exhibits excellent directional control.

A little forward bar raises the tail, and the Waiex-B takes off easily on its own.

The setting of the initial climb attitude requires the application of a very light force, but the airplane is stable.

In the ascent position, the visibility above the muzzle was good, but I could not help but give, every now and then, a "pedal stroke", to move the muzzle and make sure that there was no one who had snuck in front and below us. After all, here we are in the airspace of Oshkosh, but it is easy to forget how much traffic there is, compared to that particular week of the year (when the big air rally takes place).

Leaving the airspace of Oshkosh airport, we took flight leveled over the varied landscape of Wisconsin, and we tasted the airplane a little. Those who are used to the original Waiex will find very few differences in piloting the B-Model; and we certainly have not experienced any. The aerodynamic controls are light and effective, and turns with various angles, including steep tilt angles, were easy.

Due to the new anti-reflective eyelid, the view is a little different; but it does not take long to find the reference points with various tack angles to turn at a constant altitude.

I found that the Waiex - B remains in trim almost regardless of the attitude and speed. In other words, the force required with the untrimmed plane was light enough; so keeping the trim leveled by hand was as simple as turning the trim knob, located on the left side of the instrument panel.

The trim is based on a spring-loaded compensation system; but there would be no problem piloting the Waiex - B even if the trim didn't work at all.

The plane was stable but light around the transverse pitch axis, when we tried it in slow flight, then pulling the bar towards us to test the stall characteristics. By applying light force until the beginning of the green arc of the anemometer, we only achieved a slight shaking and an increase in the rate of descent. By pulling a little more aggressively, towards the stall without the engine, they got the muzzle falling coupled with a roll to the right.

With the hyperstainers extracted, we perceived the tendency of the bar to neutralize: an indication that there is still some work to be done, as regards the definition of the excursion of the center of gravity (CG) of the Waiex -B.

The pilot and passenger sit behind the CG, and one more person, in this case, has further set back the center of gravity.

This time we didn't try stunts, even if the plane is built to do them, since we didn't wear a parachute and we were two. But nibbling a bit at the edges with some steep tack, chandelle and eight lenses we have seen that, like all the other Sonex, the Waiex-B should also prove to be a very fun plane for those who like to explore some unusual set up from time to time .

Visibility from the cockpit is very good, as if all the other Sonex aircraft. The light in the passenger compartment is more than enough to give you the feeling that you are part of the sky. The high hood makes the cabin spacious for pilots of any size. You have to be really big and big, to hit your head on the canopy plexiglass.

The larger panel was built without giving up space for either the femurs or the knees, and I would seriously consider using the central bar instead of the two conventional individual bars.

Back on the earth

A quick radio call to the Oshkosh tower brought us back to a leeward right for runway 27, along with other planes who were taking advantage of the abnormal good weather in November. Having stretched out on the leeward lake, I kept my speed a little higher and the flaps retracted until we were dry, and stabilized on the final arm of the approach. It's just that I'm always a little superstitious, when it comes to flying a new plane over a frozen lake, who knows. But it was easy to set up the Waiex - B, and lower the flaps to reach the recommended approach speed of 90 miles per hour (78 knots).

The flaps are a bit slow to extend and retract, but only when compared to the immediacy with which the manual hyperstainers of similar Sonex aircraft operate.

In approach everything took place at a normal pace, and in that couple of landings we made, we settled with the flaps all extended or lowered only partially.

The Waiex - B does not stand on the ground with a very high muzzle; and the difference between the approach and landing arrangements is not as marked as one might expect from a pilot accustomed to a Cub-like plane, for example.

Don't call too much the first few times, or you'll risk touching the wheel first. A sweet callback worked very well for both of our landings, and directional control remained positive throughout the maneuver.

For those who are accustomed to pedal brakes (operated by the heels or toes), it may take a bit of retraining of the leg and arm muscles to learn how to use the handbrake; but everything is fine after only a few minutes of continuous use.

Aeronautical design has always been an evolutionary process. Improvements are gradually being made, and the design of an airplane is never completely finished. The Sonex and Waiex model B are a clear example. Although the original designs of Sonex Aircraft LLC are "solid" and have been sold in discreet quantities, the company was not happy to rest on its laurels and to continue with the same production.

The B models are the result of innovative ideas from various sources, including the many manufacturers around the world. Although the most important design changes have been conceived in the company, many small ideas - such as the supplementary closing of the hood, which allows better ventilation on the ground - come from customers. It was easy for Sonex to incorporate these changes as the design modernized.

With plenty of room for larger EFIS screens, and more than anything you want in the panel, version B should sell better among the pilots who are gearing up for more demanding "cross-country" transfer flights. The additional comfort of the new seating position, and the wider width of the cockpit will also help to achieve that goal very well.

Personally, I have not discovered any deterioration, due to the changes, which make this a series B version.

Unless you've already started an original Sonex, and you're already well underway (like us in our workshop), I can't think of any reason not to opt for the B model.

Take a look at it the next time you see one at a salon or gathering;

or switch to Sonex to see if it fits you.

A comfortable interior with more choices: what could be better?

Features and performance

Sonex Aircraft LLC

Waiex – B

Expected kit price (May 2017): $ 24,318

Estimated completion cost: $ 36827 - $ 51563 (US dollars).

Flying specimens (May 2017): 1

Estimated time required for construction: 700 hours

Engine: AeroVee Turbo 100 hp (74.5 kW) at 3400 rpm

Propeller: Sensenich two-blade fixed pitch

Optional engines: from 80 to 130 hp (from 50.6 to 96.9 kW): AeroVee, Jabiru, ULPower, Rotax.


Wingspan: 6.70 m

Wing load: kg / m² 54.68 - 57.12

Fuel capacity: 75.60 liters

Maximum takeoff weight: 522 kg

Empty weight: 281.4 kg

Payload: 240.6 kg

Payload with maximum fuel: 186.1 kg

Seats: 2

Cabin width: 101 cm

Boot capacity: 18 kg


Cruising speed: (TAS at 8000 feet) knots 130 - 152

Maximum rate of climb: 1100 to 2000 feet per minute

(based on excess power)

Vs0: Knots 34.7

Vs1: Knots 40

Take-off distance: from m 76 to m 121

(Data provided by Sonex Aircraft LLC)

No kits will be abandoned.

The new B models have definitively replaced the original Sonex and Waiex in the Sonex Aircraft LLC product range. So what happens to the manufacturers who find themselves with a partially finished airplane of the previous generation? There are two possibilities. Partial assembly boxes are still available, and of course the company's total assistance, for those manufacturers who want to complete their Sonex and Waiex as they were originally designed.

Kits are also available, i.e. conversion assembly boxes that allow you to complete an original project as a model - B. The conversion kits of course are based on the fact that a builder progresses in his construction work to a certain point, where the change can be applied. Some builders will have to continue the construction work to the point where the conversion kit can be applied. It may also be that others instead have to remove certain already assembled parts of the plane, in order to return to the starting point of the conversion.

The decision to complete a Sonex with the original components or as a model - B lies solely with the manufacturer. What path to take will probably depend on the work that has already been done.

But in any case it is always nice to have a choice.

Reprinted with permission of Kitplanes Magazine Copyright 2017. For more information visit www.kitplanes.com

This article was published in the May 2017 issue of the U.S. magazine Kitplanes , which is the official body of "amateur" aircraft manufacturers and designers. I thank Mr. Timothy Cole for permission to translate and publish it.

As for the characteristics and performance of the Waiex - B, it will soon be possible to have more updated ones on the company website: Sonex Aircraft LLC.

Take a look at it, because there are some very interesting news; including a personal jet, il SubSonex, which is amazing the self-built world.

Your comments will be extremely welcome


L. Pavese

John Monnett of Sonex, Ltd. with the Xenos motorglider.

Above: John Monnett and the brand new Xenos - B motor glider,
which will be the subject of a future article.

John Monnett, president of Sonex Aircraft LLC and designer of Waiex - B, was a twenty six year old drawing teacher in a middle school, when he gave in to the unstoppable impulse to design an airplane (he had already built one), after visiting the Fly rally -In Oshkosh (Wisconsin), in 1970.

Monnett wanted to build a Formula Vee racing plane; but the most difficult thing was that he wanted to finish it in time to fly it to Oshkosh the following year.

(Formula Vee was a category of US racing aircraft, and required a wingspan of 6.96 m² and the use of a Volkswagen-derived engine. Insite in the requirements were the extreme simplicity of design and construction, and therefore the reduced cost. Volkswagen-derived aircraft engines have been used on self-built airplanes for a long time; and in Europe they have also been installed on airplanes with certificate of airworthiness).

Monnett's project, called Sonerai, did not have time to be flown to Oshkosh, where he made only a field circuit; but nevertheless it became the most popular Formula Vee racing plane.

Above: Monnett with his Sonerai

Sonerai's design was very conventional and simple. It had a rectangular riveted metal wing, a fuselage of welded steel tubes covered with cloth and a "fiberglass" engine cowling.

Monnett added, however, a characteristic that suggests that he had in mind not only the races: namely the folding wings.

At the end of a day of flight, after sailing by jumping from tin to wheat field and following the roads, and after consuming only twenty liters of petrol for cars, the wings folded neatly along the sides, the tail wheel hooked to the car, and the plane was towed home on its wheels.

The Sonerai soon became known as an airplane that could be built in a short time, that is, in less than 800 hours. The plane combined very docile flight characteristics and low operating costs - qualities that are still found today in the Sonex and Waiex line - and launched the career of aeronautical designer for John Monnett.

It would take too long to list all the interesting aircraft designed by Monnett here. It is enough to do a little research, to realize the contribution he has made to private aviation. But the best way is probably to build a Waiex - B.

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The cross-legged landing

By Jon Cadd (Translated and adapted by L. Pavese)

Cessna Skywagon II 185
Un Cessna 185

The phone rang, and on the other end was my friend Simon Rodger who was calling me from South Africa. He had had some trouble with his Cessna 185 and, since I had specialized in working on them, and I had taught Simon to pilot his, he had thought that maybe I could help him. He had purchased that particular 185 from the Mission Aviation Fellowship, thanks to one of our fleet renewal programs. The plane had just come out of a commercial workshop, after a change of registration and the replacement of the cracked structural elements of the landing gear. It would have been one of the first flights on the plane after repairs. There was a vibration in the tail wheel, but the plane, according to Simon, was much more difficult to fly than he remembered, and he thought that perhaps it would have been better if we had flown a little together again, for a review .

Simon said he would come up to us immediately, and I agreed to take a look at the airplane. When Simon arrived, we hauled the plane into the hangar and I tailed it up on an easel. It was not difficult to discover the problem with the tail wheel: the wrong bolts had been screwed into the holes that secured the leaf springs, so the wheel flickered all the way round. I started to get the right bolts, but as I passed in front of the plane I noticed something busted in the main landing gear. On the front edge of the elastic steel legs of the landing gear there were rusty grooves, which had been repainted, and which were precisely the size of the supports that support the hydraulic fluid ducts of the brakes; which should be located along the rear edge of the trolley legs. The duct supports had been glued (along the rear edge) with Super-Glue. Very strange. Everything seemed upside down!

The Cessna 185 is a two-wheeled trolley plane, and like all its like it is a bit bizarre. It must be piloted step by step until it has been parked in the hangar; so if the driver is not always a little "on who lives", things on the track can go badly very quickly. Simon said it seemed that he could no longer estimate where the runway was, and that therefore the plane bounced and behaved in an unpredictable way. Indeed, even once Simon was taxiing towards the fuel pumps and when he had braked to slow the airplane he had soared up, and he had managed to prevent him from rolling over just by pulling the handwheel all the way back and giving the whole engine. A terrifying thing, a few meters from the petrol pumps; and I'm not so sure that I would have reacted so quickly!

There was another Cessna 185, of the National Parks Service, parked on the ramp, so I went to take a look at his trolley, to see if I could understand what the problem was. Everything became clear to me as soon as I looked at the second plane. Simon's cart was upside down! So now the wheels were set back from 20 to 25 centimeters, compared to the center of gravity of the plane; which, as far as taxiing is concerned, is completely wrong.

Il 185 con il carrello a rovescio
The 185 with the inverted gear

Now it was clear why the plane had almost flipped forward! When the carriage is mounted correctly, the front edge of the leaf springs is straight, and the rear edge is a little angled. When they had made the repairs, they had mounted the force elements of the reverse trolley, after which they had to swap places for the crossbows to match them; so now the left crossbow was on the right and vice versa. They should have understood this when they had to do all that work to remove the brake line supports and glue them to the other side!

I supporti dei condotti del fluido dei freni, incollati sul bordo sbagliato
The brake fluid pipe holders, glued on the wrong edge
Infine, un 185 con le balestre montate correttamente
Finally, an 185 with the leaf springs mounted correctly

I told Simon that I was very proud of him for being able to keep the plane straight in those circumstances. Such a thing had already happened. When the pilot had gone out with the plane to test it, he had braked to stop and do the pre-flight checks and the plane was on the nose, hitting the propeller and doing great damage.

It is not uncommon to think that you have performed some operation with precision, when even the slightest mistake in placing the parts or information, even if right, can lead to disastrous consequences.

This is the translation of an article that Non Cade had published some time ago on his blog, Captain's Blog-Africa.

Jon Cadd
Jon Cadd

Jon Cadd now pilots a Cessna 208 Caravan for the M.A.F., but has accumulated more than 13500 flight hours, piloting light aircraft, taking off and landing from all types of terrain, in the Pacific, in the United States and especially in Africa.

I hope you enjoyed the piece on the crooked-legged plane, and your comments will be very welcome. Thank you,

L. Pavese

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