August 2002, pp. 60-64.
The last time we met was… more than fifteen years ago for the first flight of the D-19 at Marennes. Last May he appeared – right on the minute as is his habit – at the corner of a hangar on the tarmac at Rochefort. Nothing had changed during those fifteen years: the same silhouette, the same face and the same vocabulary, very full of ‘cocky Parisian’ imagery. If Monsieur Hulot is recognizable by his hat and umbrella, Jean Delemontez is recognizable in his cotton sun hat and his language.
Even if he has removed the sign on his desk, “Smoke at Your Place,” that faced his interviewer, the tone remains alert and direct – he means just what he says. A very active retiree, he remains interested by aviation. He lives in his home baptized ‘Jodel,’ somewhere in Charent-Maritime. If at nearly 85 years of age, he notes that with the passing of the years – “the memory fails a little…” – he remains able to recount an anecdote as if the event occurred the day before rather than thirty years before…
Born in Isère, he pursued his studies at Grenoble – where physics and mathematics were more his passion than other subjects. However with a worker father, he did not have the financial means to continue his studies and, as an only children, did not have access to a loan. So, even though such a course did not please his father, he enlisted in Airforce (the Army of the Air in France), in order to pursue his studies at the school of mechanics at Rochefort. Ten months to learn the basics…
Even today, he has fond memories of that period, “the courses were difficult but interesting and well taught.” He remembers doing morning military exercises in wooden shoes, sabots, before going to the classrooms or to the shops for practical work. The material placed at the disposition of the apprentice is important when it comes to learning from concrete experience. At Rochefort, the students were required to discover the cause of engine problems created by their instructors, afterwards the roles were reversed with students creating problems for the instructors – in this play, Jean Delemontez was quickly recognized for his ability to create subtle problems.
Sunday was a day to go out on the town (14 km by foot) attired in puttees and hat while crossing the villages. He left for Rochefort a ‘skinny kid’ and returned a man, with diploma in hand…
Aviation mechanics license in his pocket – “with an additional half pay giving almost the same as that for pilots at the time” – he arrived in 1936 at Dijon-Longvic where a fighter squadron of Nieuport 96s and Ni-62 was based along with a squadron of Bloch 210 bombers. He was assigned to the 3rd Squadron, 7th Flight (3/7) and, on arrival, he was designated “zero.” The convention was that the chief pilot flew aeroplane 1 and his companions flew 2 and 3, the other pilots took the other planes. The “0” was the aeroplane not assigned to a pilot, the spare, generally the oldest and/or the least performing. Rightly named, this “0” was on its last legs. It landed but… didn’t make it to the hangars. The landing gear were worn out. On that particular model, the landing gear is rigid and poorly attached. Thus, hardly having arrived at the base, Jean Delemontez received an order to go and fix it.
The never-idle mechanics were on a constant merry-go-round of activity.
Delemontez was soon known for his competence, his mechanical sense and resourcefulness which, despite his numerous requests, kept him from being granted the opportunity to train as a pilot…
After the Ni-62’s came the Spad 510, the last biplane in service of the Army of the Air, which was technologically behind the times, the Morane-Saulnier finally arrived, “a modern aeroplane” but quickly surpassed, notably in performance, by the German competition.
The war broke out and Jean Delemontez followed his unit to the Vitry-le-François region with orders “to get as many planes in the air as possible.” Having the confidence of his superiors, he organized himself, selected his team members and prepared his repair material or “collected parts” from other planes in the country.
Soon he returned to Toulouse with eight, newly broken in, Dewoitine D-520s, a “beautiful plane.” They had a potential of only 220 hours, but that’s a lot in war time.
To get to England, he boarded a single-palce D-220 with a pilot who left his parachute behind to gain enough space, but as they were taxiing, it became apparent that two in a mono-place would be difficult and the adventure stopped there… He learned that Albert Littolf thought to go to Britain with three mechanics on board a Caudorn Simoun. They had boarded the plane but didn’t depart as the calculations indicated that the plane could not travel that far without a very strong tail wind. Albert Littolf finally made it to Britain in a D-520 before going on to become famous in the heart of Normandie-Niémen…
As the last hope for Jean Delemontez, his unit would go to North Africa, and he received orders to embark aboard a Bloch 220 going to Algeria. However, when he arrived at the aerodrome, the plane was already taking off… Fortunately as it turned out, because a counter-order for his unit had already arrived! It amuses him to imagine himself all alone in Algeria waiting indefinitely for his squadron …
In 1941, he quit the army to work as project manager on the transformation of the bi-motor Amiot, in conjunction with the design staff, in the shop of Atelier Industrial de l’Aéronautique in Blagnac. While there he benefited from a drawing board and heat which encouraged him to spend additional hours in the shop… for his proper projects. It was there that his first light plane designs took form.
Light aviation attracted him. Before the war, he had already gone from Dijon to Beaune to see the HM-14, Pou du-Ciel, of a certain Edouard Joly. The latter was an ‘expert’ on the engine designed by Henri Mignet. But when our young mechanic arrived with his companion, Adonis Moulène (the future fighter and test pilot for Max Holste), he learned that Edouard Joly had disassembled his Pou and dispersed the parts in several hangars to evade all temptation for reconstruction. After several accidents with the Pou, his wife had forbidden him to fly with that engine. The two men became friends, and Jean Delemontez came each Sunday for further discussions with Joly. Joly’s daughter was certainly part of the reason for these visits because he latter married her.
Thus, in 1942, when the control of the Germans weighed heavy on the organization of the AIA of Blagnac, Jean Delemontez obtained authorization to quit the shop to “return to the land,” to officially aid ‘farmer’ Joly with the repair of his agricultural machines… The return to Bourgogne he describes as a period of … vacation, with one day of work per week and the rest of the time utilized to refine his aeronautical projects. He cites his CAB44, a ULM before its time, planned for 1944 for the Construction Aéronautiquees Beaunoise! With its high, flex wing and its 180 kg, the machine was a derivative of a motorized bi-place metal glider of Edouard Joly. The construction was started but the use of duralumin was difficult and the plane was never finished.
At the end of the war, our two collaborators had their heads full of projects. In 1946, they founded the Avions Jodel company (JOly-DELemontez), which had as a goal, “the design, construction and repair of all material aérien.” The first contracts concerned the repair of some gliders for the Service de l’aviation légère et sportive (Light and sport aviation service - Sals), the ancestor of the Sfa, and the Sfact. During his quiet moments, Jean Delemontez finished the design of his ninth project.
Since he did not have a drawing board in 1947, he drew the plans directly on the plywood because he “never had any intention to build a second.” From the disassembled Pou, he recovered the Poinsard motor for the D-9, a mono-place that would become better known under the name of … Bébé Jodel.
The entire design philosophy of the father of the Jodel line was already concentrated in the little low-wing monoplane. Build it simple, light and don’t sacrifice performance to be fashionable. And it possessed the Delemontez wing, with its rectangular center section in one piece to simplify construction and its trapezoidal extremities supporting the ailerons. This wing had nearly the same properties of an elliptical wing that produces an ideal lift distribution. To optimize the design, the extremities of the wing had a twist, wash-out, meeting the needs for both climb and cruise. Despite it relatively short length, the wing has proven itself. The fuselage had an open cockpit with the streamlined 25 hp Poinsard motor and, in the rear, a standard elevator with a single piece, monobloc, rudder.
In January 1948, so as not to be bothered by the curious, Joly and Delemontez decided to fly the Bébé from a field used for demo flights by the Beaune aero-club rather than the aerodrome. The D-9 was disassembled and put on a trailer ready for the next day… Unfortunately, during the night, thirty centimeters of snow fell and the field was not usable. However, our two friends reassembled the D-9 at Beaune and then … started the motor. When the latter was warm, why not try some taxiing? The ceiling lifted a little (about 150 meters), the conditions were calm and the machine “wanted to fly.” So Edouard Joly advanced the throttle a little, and the Bébé Jodel took to the air. Jean Delemontez saw, in the first minutes of flight, “that the plane worked.” Ninth project, first to take to the air…
After 80 hours, the Poinsard motor gave up the ghost. During that time, Joly experienced eight in-flight engine failures of which three ended up among the grape vines… Jean Delemontez paid tribute to the pilotage of his companion. He “was lucky” and sometimes landed in a vineyard with only ‘fifty centimeters clearance on each side of the fuselage.” Edouard Joly died in 1982.
The first flights were left to E. Joly, who had more experience, but J. Delemontez was already a pilot too. He trained on a Stampe, at the Beaune aero-club. The runway was a short strip (250 meters long and 8 meters wide), built by the Americans with several passes of a bulldozer, for the operation of Piper J-3s. At one end of the runway, was a cherry tree and at the other end a pile of rocks left by the bulldozers!
J. Delemontez was part of a group of ten students instructed by one who did not have a proper instructor’s license but who did have experience training more than a hundred students. At that time, a ‘tester’ came to assure their competence before the first solo flight. Surprise, the tester was an old comrade from the 3/7 who came to check out J. Delemontez. After one trial flight, he was ready to let Delemontez solo after only 8 hours of dual… But J. Delemontez was a little reluctant to make his solo flight, because there were plans to lengthen and widen the runway in fifteen days.
If Jean Delemontez thought the Bébé Jodel would be one of a kind, he missed the mark a little. During the twenty years following the first flight, once the plans were drawn and after the CEV of Brétigny certified the prototype giving it CNRA status, more than 500 were constructed worldwide. Today the prototype rests in the Museum of the Air at Bourget. The F-PEPF is the first link in a line that is not yet finished.
After the D-9 came the D-10 3-place, put on the back shelf to develop the 2-place D-11 (Salmon 45 hp) that had greater demand. With different motors, the D-11 became the D-112 (Continental C-65), D-117 (400 constructed under license by the Societé Aéronautique Normande, SAN, managed by Lucien Quérey at Bernay), D-119 (Continental C-90) before going to the D-12 with more than 500 D-120 constructed by Wassmer Aviation.
Next, Delemontez transformed the D-10 into the 3-place DR-100 Ambassadeur (80 hp) of which 700 were constructed, half by SAN at Bernay and half by the Centre Est Aéronautique, CEA, at Dijon-Darois. The CEA was lead by a certain Pierre Robin, which is the origin of the designation DR for Delemontez-Robin.
The DR-1050 and 1051, Sicile and Sicile Record, quickly followed.
If the D-13 stayed in the box, the D-14 gave birth to the D-140, Mousquetaire, one of the rare single-engine aircraft capable of lifting a load equal to its empty weight, a 4/5-place favored by mountain fliers. After the first flight by Lucien Quérey, 4 July 1958, Jean Delemontez pursued the test regime of the D-140 with Léon Biancotto at the controls. Léon didn’t hesitate to perform a barrel-roll on his second flight. The certification flights were performed with … number 4, -- the first three planes were already in the hands of their owners.
Jean Delemontez remembers one flight in the prototype, piloted by L. Quérey, the designer simply being seated on the longeron because there was no seat on the right in order to access the control system for further tests.’
The D-150 Mascaret that followed, is the Jodel preferred by Delemontez. With 100 hp, this 2-place cruises at 220 km/h, carrying 60 kg of baggage and 190 liters of fuel. Today, a large number of the 70 constructed can be found … in Great Britain which has a very active Jodel Club.
With the death of Lucien Quérey, owner of SAN, the D-160 never saw the light of day. The company was later purchased by Avions Mudry to develop its CAP-10B and CAP-20.
In Darois, CEA had become Avions Pierre Robin and the shop produced the DR-250 (tail-dragger) and DR-253 (tricycle gear) with 150 and 160 hp. Later the DR-300 was developed and the DR-315, the Petit Prince (2+2) followed by the 4-place DR-340, Major, the DR-360, Chevalier, and the DR-380, Prince, according to the choice of motors. Finally, at the beginning of the 70’s, the DR-400 took to the air to arrive in a large majority of the national aero-clubs and at the hands of individual owners around the world.
7000 aeroplanes sport his mark ---
In parallel with the industrial versions of certain of his aeroplanes, Jean Delemontez continued his work with CNRA versions. After the DC-1 (Delemontez-Cauchy), a prototype 2-place extrapolated from the Bébé Jodel was built, Delemontez created the D-18, a tail-dragger, followed by the D-19, a tricycle version, that some would modify with retractable gear. One detail of the D-18 escaped its creator. He would have preferred a canopy of the D-112 type to the bubble canopy opening to the rear.
At the end of the 80’s, the D-18 and D-19 exited by the dozens from the ‘industrial’ shop of the Center RSA Quercy-Rouergue at Montauban, under the direction of Charles Roussoulières.
Meanwhile, even though he told us that the D-20 would “never” be designed, J. Delemontez returned to his drawing board to create that version of the 2-place destined to be distributed as a kit by SAB, at Beaune. …. (The failure of SAB has been recounted elsewhere.)
Today, Jean Delemontez estimates that about 7000 aeroplanes carry his mark. He continues to discover previously unknown versions of his planes, such as the most recent ones discovered in New Zealand and Iceland, as a result of letters or press articles various ones forward to him.
Delemontez, who has never been a salaried designer but always sold licenses, doesn’t go to Dijon-Darois as he did. He whom the employees of Avions Robin called ‘chef’ when he passed through the shop doesn’t find the same ambience at Darois as in the past. He prefers to receive the Robins at his home. (That too has changed with the demise of Avions Robin.)
These days, Jean Delemontez has been ‘pushed’ by Jacques Vion to work with him on the design for a diesel powered aeroplane. The two men know each other well. Vion built the prototype of the D-19 before building a version with retractable gear. As is his habit, Jean Delemontez resisted this last request, but one does not stop Vion…
Without a firm response from Delemontez, Vion returned to his shop and attacked the structure of the wing of his D-19 to make the conversion to retractable gear. The word circulated among the local amateur builders, and Jean Delemontez finally came to ‘inspect’ the project. Having walked around the project, he returned home. Several hours later, J. Vion received a phone call recommending various reinforcements. The master had come, had seen and had developed the modifications during the afternoon, to aid in the development of the retractable 2-place.
This time, the situation repeated itself when J. Vion brought up the idea of a diesel powered plane in a conversation. With some reluctance, Jean Delemontez returned to the drawing board, got out the plans for his D-10 3-place and his HP calculator in preparation for another design. While for him, this was an “artificial problem,” linked to the price of fuel, Delemontez was surprised by the results obtained. The result is … the Delvion (Delemontez-Vion), a diesel powered Jodel that is accumulating hours at the hands of Jacques Vion, with several different motor and prop combinations being evaluated.
Jacques Vion, with fifty years diesel experience, started with a turbocharged PSA motor without a reducer. With about 110 hp (while waiting for the more powerful version planned for the coming months), his DVD cruises at 210/220 km/h using 10 liters per hour … of kerosene (less than 5 euros per hour), or about 5 liters per 100 km! The performance, with its flat torque regime, equates to a DR-360 equipped with an O-320 producing 160 hp and consuming 35 liters of 100LL. The performance data for the PSA show that the torque actually increases when the revolutions decrease! If the power is 103 hp at 3300 rpm, it is still 100 or 99 hp at 2800 rpm, little difference in power with a drop of 500 rpm.
Some haven’t much appreciated the ‘look’ of the mounted engine, but, for Jean Delemontez, if “the look isn’t great, its aerodynamics are good” – which pleases him. He states that this direct-drive solution is the most simple, and it … works. In addition, “one needn’t bother with a variable pitch prop.”
That reminds Jean Delemontez of the attempts to use a variable pitch prop with the 105 hp Potez engine. With a Jodel using a fixed pitch prop, there was no noticeable difference in performance. It “it seemed to have more push in take-off, but one used the same ground roll, and it didn’t provide additional speed in cruise.” The result was identical with the D-140 evaluated with a variable pitch prop. Delemontez knows that sometimes it’s necessary to accept the wishes of the client even if they attack long held habits and ideas. “So, if the client wanted it, we gave it to him…”
Above all, the Delvion is about experimenting with engines, not about looks. Even if the spats need to be redone for better esthetics. (A note attached to a picture in the article indicates that the Delvion spat design gives improved performance over those on the Robins.)
Jacques Vion considers the Delvion a prototype that can be powered by more powerful power plants in the coming weeks while he moves another project to the front burner, a 2-place D-11 powered by a 100 hp diesel.
The diesel motor, with a over-head crankshaft, needs to be mounted high to provide adequate ground clearance for the prop. With the cylinders on top, “that’s what you see in front of you because one can not invert a diesel,” said J. Delemontez. This configuration permits an unusually narrow cowling giving good visibility to the front.
Destined from the beginning to remain unique like the Bébé Jodel, the Delvion prototype will, in fact, be followed by a second for the Rochefort aero-club. An ‘industrial’ version has been extrapolated that will be distributed in kit form by Bachelet SARL, Rochefort, managed by Frédéric Bachelet. That model, 4-place and no longer 3-place, carries the designation D-103, because it is a derivative of the D-10 for ‘the 3rd Century.’
So, Jean Delemontez needed to take up his studies once again because “going from a 2-place to a 4-place changes everything! Having two seats with a cushion under you on the longeron is one thing. Installing two adjustable seats behind with seatbelts adds at least 6 kg. Weight increases quickly and it’s necessary to stay below the 515 kg announced in the specifications.”
If he grumbles while describing the problem, his interviewer knows that Jean Delemontez already has in mind the solutions to reduce the kilos here and there. He knows that with his DR-100 wing, “if one keeps the weight below 500 kg, one can create a 4-place with 50 liters of fuel and some baggage or a 3-place with baggage and 130 liters.”
J. Vion tellx that, the ‘chef’ has invented a totally ‘fabulous’ new system for the nose wheel. The main gear from the 4-place MCR-4S and CR-100 by Dyn’Aéro already bear the Delemontez mark. The width of the main gear will be a compromise between the Amassadeur and the DR-300.
For the wing of the D-103, identical to that of the Delvion, the modified NACA 43013 will be used once again. And the wing will have the classic Jodel form, flat, rectangular middle section with cranked tips built with a box longeron skinned with a plywood nose open beneath and fabric covered behind. Having many of the elements already calculated, Jean Delemontez estimates 2000 hours of design work for the D-103 – “The plans don’t yet exist, but I have several ideas!” A totally new design requires about 5000 hours.
Delmontez’s principal help is an HP calculator – he once tried, but quickly abandoned, a 486 mhz PC because “it doesn’t know how to calculate.” Unfortunately his HP has only a small printer and does not keep programs in memory, but it’s very practical with its characteristic ‘inverted Polish stack’ permitting one to retain the partial results to follow the evolution of the parameters…
Last May, the wing of the first D-103 was already built in the Bachelet shop but, except for the form of the monobloc tail feathers, Delemontez had not yet finalized the plans for the fuselage, based on the DR-300. A reinforcing bar is planned for the firewall to handle the motor. A 4-cylinder diesel produces a unique set of vibrations having a ‘jerky torque’ and ‘no possibility of reduction gearing’ which is why the ‘industrialization’ of the diesel for aeroplanes has not been successful so far.
The prototype of the D-103 will make its first flights at the beginning of next year (2003). The Jodel aeroplanes have entered the third millennium… Their designer is an ‘astonishing’ man, commented Pierre Robin. Even this adjective is, undoubtedly, less than the truth, but no other has been found to better describe the ‘chef.’ Oui, quite astonishing, this Monsieur Delemontez…
Translation from the French by William Raiser