I-11 / I-12 / I-17
Базирующееся в Риге латвийское государственное предприятие "Valsts Elektrotechniska Fabrika" (VEF) в 1935 году организовало авиастроительное подразделение, главным конструктором которого стал Карлис Ирбитис. Среди проектов
VEF преобладали низкопланы цельнодеревянной конструкции, первым из которых стал двухместный I-11. В 1937 году он совершил 1000-км перелет вокруг Латвии, продолжавшийся 5 ч 30 мин. На его базе был создан моноплан с закрытой кабиной I-12, совершивший первый полет в июне 1937.
Flight, August 1939
The V.E.F. J.12 in the Air : 140 m.p.h. on 90 h.p. : Control in Excelsis
DURING the last year or so a little low-wing monoplane of exceptionally clean design has been seen about quite a lot at Croydon and elsewhere. This machine, which is, at present, the one and only type of aeroplane produced in Latvia, is the J.12, built by the State-controlled aircraft section of Valsts Elektrotechniska Fabrina, a firm which specialised in the manufacture of precision apparatus of various kinds. Since Latvia is a timber-growing country it might be expected that the J.12 is of all-wood construction. Its predecessor, the J-11, first appeared in 1936, and the J.12 is a considerably cleaned up and strengthened version designed for fast, economical private transport and aerobatic work.
Certainly, it is quite one of the cleanest machines in the smaller class - a fact which is obvious from the performance figures on the mere 90 h.p. of a Cirrus Minor engine. Nowhere on the machine can a joint be seen, and both wings and fin at perfectly faired into the fuselage. The construction is quite simple and orthodox, with the wing in three sections, of which the centre-section is virtually part of the fuselage structure. There is one main box spar and one auxiliary spar and the wing is entirely ply-covered. The fuselage is a box structure with a strut-braced tailplane intentionally mounted rather high above the fuselage in order to obtain good stalling and normal spinning characteristics. The two legs of the undercarriage are cantilever and, perhaps, even too effectively faired in from the mud and maintenance points of view.
The ailerons are of the slotted type and these are the most delightful feature of the J.12 treated as a flying machine. Not only are they light at all speeds, but their reactions are so instantaneous that the wing, so to speak, just follows the control column. At the same time they are fully effective down to the stall, which does not arrive too suddenly. In fact, the machine can be flown indefinitely at practically stalling speed and only when the column is eased firmly right back does the true stall occur, with the usual reactions.
Immediately inboard of the ailerons are the flaps, which extend on each side of the centre section. These are also slotted and, while being extremely effective at comparatively high speeds, do not cause so much drag at lower speeds that the landing process is unduly abbreviated. There is quite a perceptible floating period after checking slowly from the normal gliding speed of 100 km h (62 m.p.h.). Furthermore, the effect of these flaps when first applied is to push the nose down, and, left to itself, the machine takes up a more or less correct gliding angle. They are directly operated by means of a lever on the left of the pilot's cockpit, and can be left in half a dozen different positions, the first one (giving io degrees or so) being used for take-off.
Provided that such a readjustment is not made at the last moment, it is quite practicable to use the flaps as a means of shortening or stretching the glide. The best way of making an approach seems to be to come in on the usual right-angle course with the flaps in the half-down position, using the remaining movement to kill any excess height as the boundary is about to be crossed. By way of further adjustment the J.12 will sideslip quite satisfactorily so long as the slip is not allowed to become too steep.
With an aerobatic harness which tended to slip off the shoulders and an old gentlemanly dislike of aerobatics on a strange machine, I was satisfied to use the aileron control only for steep turns, but it was sufficiently educative to change bank several times through 180 degrees, and to make one straightforward, wide radius loop. The aileron control is such that one tends to progress in a series of quarter-rolls just for the pleasure of using it. The machine which is at present over here has its instruments calibrated in the metric system - as well as a fuel tap, controlling the feed from the two tanks, marked with letters which require considerable concentration if it is not to be turned to the "oil" position by accident. When I flew it the revolution counter was out of action, but, with the throttle set at a position halfway through its quadrant, the J.12 flew level at an indicated speed of 220 km/h.
This, with adjustment for height, works out at 139 m.p.h. The engine revolutions may have been higher than I thought, or the instrument might have suffered from position error. An up-and-downwind trip of 151 miles - including some three or four minutes of slow-flying tests - was made, take-off to landing, in 1 hr. 15 min. Allowing (ungenerously or not) a total of five minutes for the take-off, landing, circuits, and stall experimentation, and forgetting the adverse all in effect of the wind on the two legs, this gives an average speed of exactly 130 m.p.h.
The wing-loading is not unusually high, the landing speed does not seem to be much higher than 45 m.p.h., and the flaps more than take the edge off the approach - but such a performance is not obtainable without some sacrifice. In this case the sacrifices are tn forward view and length of take-off run. The latter is not excessive when the flaps are used, but some distance is covered before the machine is really under way and climbing satisfactorily. Without an r.p.m. indicator it is impossible to judge such things, but I felt that I would not be ready to lose 5 m.p.h. in the cruising speed to obtain a little more urge during the crucial stages of the take-off. Possibly a metal airscrew would make that little difference.
In our crowded skies, the view question is rather more serious, but there is no reason at all why the J.12 should not be laid out in open two-seater form, with carefully designed individual screens. The transparent cabin-top idea clears the lines very much and makes it a very comfortable and quiet aeroplane - but, again, I will lose another 5 m.p.h. to be able to see straight ahead. Theoretically this should be possible with the enclosure, but, in fact, the effects of perspective and distortion make the forward view almost worthless. I met a squadron of Wellingtons on their way back from Paris and flying at my own height, so perhaps I am biassed.
These two points can possibly be rectified, but certainly mar the near perfection of the J.12 as a flying machine. In the circumstances the rectification would be well worth while. There is no other machine in its class and available in this country with quite the same characteristics.
H. A. T.
90 h.p. Cirrus Minor engine
Span 30ft. 6in.
Length 23ft. 8in.
Wing area 122 sq. ft.
Weight empty 1,012 lb.
All-up weight 1,500 lb.
Wing loading 12.3 lb./sq.ft.
Power loading 16.7 lb./h.p.
Maximum speed 148 m.p.h.
Cruising speed 124 m.p.h.
Landing speed 47 m.p.h.
Endurance at cruising speed 4 hours.
Concessionaires D.R.P. Engines. Ltd., Gatwick Airport, Horley. Surrey.
POWER FROM BROUGH. The V.E.F. J.-11, a light Latvian private-owner type built round one of the new Cirrus Minor engines. The speed figures quoted are 124 m.p.h. cruising and 149 m.p.h. maximum, which, for 90 h.p. and two up is good going in any language. The mounting of the tail plane is one outlandish feature to note. It appears that the occupant of the front seat has quite an extraordinarily good prospect.
CIRRUS-MINOR-ENGINED, this Latvian V.E.F. J-11 monoplane recently made a circuit of its native country in 5 hrs. 20 mins. for the 655 miles, including several demonstration stops; the average flying speed was 125 m.p.h. The machine is shortly coming to England, and those interested in demonstrations should write to Mr. Janis Vitols, 24, Queensborough Terrace, London, W.2.
The V.E.F. J-11 machine CIRRUS " MINOR." Top speed nearly 150 m.p.h.
The fascinating little Latvian V.E.F. 12 which was judged the smartest machine on parade.
I-12 был оснащен 90-сильным (67 кВт) ПД Cirrus Minor; около 12 таких самолетов были построены для гражданского и военного использования. Некоторые из них служили в ВВС Латвии.
Whilst the early Irbitis designs were high-wing monoplanes, all the later aircraft were low-wing types (shown, I-12).
The clean lines of the V.E.F. are obvious in this photograph, taken during the Isle of Man races. The ailerons do not, as they appear, extend from centre section to wing tip - the inner portions are slotted flaps.
An untouched photograph taken by Flight with the miniature camera. It shows the V.E.F. J12 cabin monoplane at Ronaldsway, Isle of Man.
The two leading machines, the Klemm in the foreground and the V.E.F. on the left. Two of the four Gauntlets at the meeting may be distinguished in the background.
The V.E.F. I-12 Two-seat Light Cabin Monoplane (90 h.p. Cirrus "Minor" engine).
ECONOMICAL SPEED: The Valsts Elektrotechniska Fabrika J.12, for which Rollasons of Croydon are agents in this country. With an 80/90 Cirrus Minor engine this little two-seater cruises at 123 m.p.h. and has a maximum of 149 m.p.h. One or two minor modifications are being made to the later production machines in order to bring them into line with British C. of A. requirements. Among other interesting features the J.12 has manually applied split flaps and differentially operated slotted ailerons.
The transparent enclosure arrangement on the J.12. The rear portion slides and can be left in any position, while that over the front seat lifts. There is a wide luggage locker behind the rear seat.
THE ILL WIND: A corner of Rollason's hangar at Croydon. In the foreground is a Stinson Reliant, with the little Latvian V.E.F. J.12 behind it and the South African Junkers Junior on the right. One of I.A.F.'s Curtiss Condor freighters can be seen in the far distance.
Almost ready. An excellent photo showing the I-16 nearing completion. Many structural details are readily apparent. A VEF I-12 is in the foreground.
The V.E.F. I-17 basic trainer.
Aircraft designed in Latvia by Karlis Irbitis are numerous, ranging up to the sporty-looking I-17 trainer.
This three-view G.A. drawing of the J.12 helps to explain its performance.