ISF Mistral-C

Mistral-C
Type:	Glider
Design country:	BR Germany
Manufacturer:	Engineering office Straub-Frommhold GmbH (ISF), later Mistral-Flugzeugbau and finally Valentin Flugzeugbau GmbH
First flight:	October 21, 1976
Number of pieces:	75+

In 1974 the Mistral-C was one of the first gliders to be designed according to the rules of the then new club class . It is based on the Straub Mistral , but was given a new wing geometry with a lower aspect ratio, a dampened horizontal stabilizer and was built from more modern composite materials. Both types of aircraft were designed in Germany . In total, more than 75 Mistral-C were produced.

history

The direct forerunner of the Mistral-C was the standard class glider, the Straub Mistral , which was designed by Manfred Straub, Alois Fries, Hartmut Frommhold and Horst Gaber. Construction began in January 1970 and the Mistral's maiden flight took place in July 1975. Series production of the original Mistral was not planned.

In October 1974, Straub and Frommhold began designing a new aircraft model, the Mistral-C, under the new name of Ingenieur-Büro Stolzen-Frommhold GmbH (ISF) . This aircraft was supposed to be one of the first to meet the regulations of the FAI Club class, which was then newly introduced . The first flight took place on October 21, 1976.

By the beginning of 1980, the ISF had produced 25 aircraft. The number of aircraft built up to the first half of 1981 after the name was changed to Mistral-Flugzeugbau is unknown. Valentin Flugzeugbau produced 50 more Mistral-Cs in the Mistral-Flugzeugbau plant by the beginning of 1984.

construction

Straub Mistral

The Straub Mistral was a shoulder wing made of glass fiber reinforced plastic (GRP) with a 15-meter span and a T-tail unit . The wing area was 9.4 m² with a wing extension of 23.9. The wing had a sweep of 0.4 ° at 1/4 of the profile depth. The V position was also 0.4 °. The wing profiles used were Wortmann FX-66-S-196 at the root and FX-66-S-161 at the ends of the wing . A GRP balsa sandwich was used as the material for the wings, the ailerons consisted of GRP in conjunction with polymethacrylimide (PMI) foam. The aluminum Schempp-Hirth brake flaps only extended upwards. PMI-filled GRP was also used for the pendulum control unit. The half-shell hull of the Mistral consisted of a GRP balsa sandwich, the hood was one-piece. The single-wheel landing gear was retractable, and a grinding spur was used at the rear. The best glide ratio of the Straub Mistral was 39: 1, the lowest sink rate was 0.6 m / s.

Mistral-C

The main differences with the Mistral-C concern the wings and the materials used. The wing area was enlarged with the same span, so that wing extension and thus the power were reduced. The new wings consisted of different Wortmann profiles, the sweep was 1.0 ° and the V-position 4.30 °. The GRP balsa sandwich in the wings and tail unit was replaced by a GRP PVC foam sandwich, the ailerons and the fuselage were made entirely from GRP. Instead of a pendulum tail unit, a damped tail unit was used. The hood is hinged on the side. The Mistral-Cs later manufactured by Valentin were almost identical, only a slightly lower V-position of the wings is reported.

use

At the first International Club Class Championships in Sweden in 1979, a Mistral-C could reach 3rd place out of 33.

After major damage in a foreign landing in 1996, serial number MC027 / 81 was used in particular: The aircraft was acquired by the laboratory for flight mechanics and flight control at the Aachen University of Applied Sciences and, after being professionally repaired, served as a test vehicle in two research projects of the Federal Ministry of Transport. With the Mistral, the possibility of deploying parachute total rescue systems using pyrotechnics from a glider and landing a glider on a parachute was initially examined. After further repairs and some structural reinforcements, the aircraft was converted into a remote-controlled test vehicle and received a provisional traffic license from the Federal Aviation Office in 1999 as a "large aircraft model FHA / mistral-C" with the registration D-UFHA. Conventional components from model flying were used for control, supplemented by telemetry systems for data transmission and various security systems. In the spring of 2000 there was an unmanned remote-controlled flight with the deployment of a total rescue system in turning flight and finally a second flight with the deployment at high speed, in which the aircraft was irreparably destroyed.

In 2010 there were 54 civilly registered Mistral-Cs in Europe and another 3 were registered in the UK in 2012. The aircraft construction company Eichelsdörfer GmbH in Bamberg takes on the model support .

Technical specifications

Parameter	Data
span	15 m
Wing area	10.9 m²
Wing extension	20.7
Hull length	6.73 m
Wing profile	up to the kink: Wortmann FX61-163, at the wing end FX60-126
Empty mass	approx. 235 kg
Water ballast	-
Max. Take-off mass	350 kg
Wing loading	28 to 32 kg / m²
Top speed	250 km / h
Maneuver speed	160 km / h
Minimum speed	62 to 67 km / h
slightest sinking	0.60 ms −1 at min. and 0.66 ms −1 at max. Wing loading
best gliding	35.1
Glider index	96
Max. Load factor	at 160 km / h: +5.3 ..- 2.65 g, at 250 km / h: +4 ..- 1.5 g

Individual evidence

1. ^ ^{A b} Michael Hardy: Gliders & Sailplanes of the World . Ian Allen Ltd, London 1982, ISBN 0-7110-1152-4 , pp. 60 .
2. ^ ^{A b} John WR Taylor: Jane's All the World's Aircraft 1984-1985 . Jane's Publishing Co., London 1984, ISBN 0-7106-0801-2 , pp. 638 .
3. ^ John WR Taylor: Jane's All the World's Aircraft 1976-77 . Jane's Yearbooks, London 1973, ISBN 0-354-00538-3 , pp. 572 .
4. ^ John WR Taylor: Jane's All the World's Aircraft 1980-1981 . Jane's Publishing Co., London 1980, ISBN 0-7106-0705-9 , pp. 670 .
5. ↑ Röger, Conradi, Ohnimus: occupant safety in aviation equipment . Federal Ministry of Transport, 1996 (Research Report FE No. L-4 / 94-50129 / 94).
6. ^ Röger, Conradi, Schäfer: Development of verification methods for the traffic safety of gliders and motor gliders . Federal Ministry of Transport, Building and Housing, 2002 (Research Report FE No. L-1 / 98-50169 / 98).
7. ↑ Dave Partington: European registers handbook 2010 . Air Britain (Historians) Ltd, 2010, ISBN 978-0-85130-425-0 .
8. ^ Mistral-C on CAA register. Retrieved September 7, 2012 .  
9. ↑ Mistral aircraft construction: Mistral-C product brochure. Retrieved December 29, 2012 .  
10. ↑ Engineer office Dipl.-Ing. Straub - Frommhold GmbH & Co. KG: flight manual / maintenance manual mistral-C. (No longer available online.) December 21, 1977, formerly in the original ; Retrieved December 29, 2012 .  ( Page no longer available , search in web archives )