WesWorld

The relatively poor performance of the IAR 80 at the Talons 38 competition showed to IAR a need for more power. The problem of course was attempting to find that power, IAR was a small company, and although there had been some cooperation with Poland's larger PZL in the past, neither was in the business of developing more powerful motors for IAR. Therefore, IAR went to Gnome-Rhone for engines once again. Although the Germans did have more powerful engines available to sell, IAR decided to go with proven Gnome-Rhone. Gnome-Rhone had their new 14R ready which more than met the requirements of IAR for more power. Actually, the design would require some strengthening of the airframe in general to work in the IAR 80, so for the interim a derated verion of the 14R would be fitted to the basic IAR 80 frame, which itself would have to be strengthend. Unfortunately, despite the rush job placed on it by the Romanian government, it would just miss Talons 39, but would compete in Talons 40 with its uprated cousin, the IAR 81A.



IAR 81

General characteristics

Crew: one, pilot
Length: 8.97 m (29 ft 5 in)
Wingspan: 11 m (36 ft 1 in)
Height: 3.535 m (11 ft 7 in)
Wing area: 17 m² (183 ft²)
Empty weight: 2500 kg (5,512 lb)
Max takeoff weight: 3250 kg (7,165 lb)
Powerplant: 1× IAR K14R air-cooled 14 cylinder double-row radial, (1,400hp)

Performance

Maximum speed: 625 km/h (388 mph)
Range: 730 km on internal fuel only/1330 km with extra fuel tanks (394 nm, 454 mi/718 nm, 826 mi)
Service ceiling: 10,000 m (32,800 ft)
Wing loading: 132.35 kg/m² (27.1 lb/ft²)

Armament

2 × 20 mm MG 151/20 cannon and 4 × 7.92 mm FN machine guns mounted in the inner portion of the wing; provision for one 225 kg (500 lb) bomb under the fuselage

Looks pretty good. I can't find much information available on the 14R. 625km/h is probably a bit fast with 1400hp given that 600km/h was estimated with the 1600hp BMW801.

The 14R was the final version of the whole 14 series, it was mainly the 14N with a 2 stage supercharger I belive. The most powerful version was rated at 1,600hp which I felt was too much for the current airframe to handle, so I derated it to 1,400hp. Interestingly enough, the French put the 14R into the Bloch M.B. 157 as a prototype which the Germans tested after the Armistice in 1942, and the performance of the aircraft was quite astonishing, reaching 710 km/h. Mind you, I got that spec from the Virtual Aircraft Museum, so it may be a bit dodgy, but still. If you think the speed is abit high, I could derate it to around 580 km/h, but then I might as well continue building IAR 80s.

I am doing the IAR 80 development in smaller steps, with a 1400hp engine, then a 1600hp engine in a strengthened airframe. After that, either I enlarge the airframe to fit a BMW 801, go with an inline, or see if Agent has developed the 14 series any further.

Quoted

The 14R was the final version of the whole 14 series, it was mainly the 14N with a 2 stage supercharger I belive.

Ah, I thought it was that one initially but couldn't pin it down. It's not really a two stage supercharger as such, its a standard centrifugal flow type with three variable pitch axial stages in front which vary the overall compression ratio. My impression was that it didn't work all that well. With some power available at altitude and a lighter engine than the BMW 801 I suppose 625km/h is reasonable. DB601 and annular radiator for the future?

The Bloch MB.157 performance seems rather wrong. I reckon it's a case of a mix up when converting between kts/mph/kph as with a few conversions you end up with a much more expected speed. Stranger things have happened though - like the 502mph speed widely quoted for the CAC-15 Kangaroo - turns out that was in a steep dive.

Funny thing is, I currently hold in my hands a magazin called "Flugzeug Classic", issue 6 for June 2010, that contains a long article on the Bloch MB 150 series. According to that source the MB 157 was captured by the Germans on the 9th of June 1940. She was not yet finished, a prototype not yet ready to fly. The aircraft featured a G&R 14R-4 engine with two stage charger and 1700hp max power and was aerodynamically improved. Under German supervision the plane was finised and had her first flight in March 42. During test flights she later reached 710km/h at an altitude of 7850m, revealing the potential that was hidden in Marcel Blocks original, a bit cumbersome design. The bird remained a single example and was later destroyed in an allied air raid.

The text mentions several sources I am too tired to write down here. So there is a chance those figures are correct although there is no information on the state of the MB 157 during those test flights. Without armor, armament and much fuel, hence in light weight condition, she might have been able to reach high speeds at altitude.

I'd be interested in those sources Hoo, seeing as one of my largest sources of aircraft comes from Ripon-Bloch. I'm assuming they are in german though? (drats!)

Quoted

Originally posted by thesmilingassassin
I'm assuming they are in german though? (drats!)

Ucz si jzyków.

Don't let that stop you.
Figuring out a foreign technical text far easier that foreign poetry.

Good point Marek.

Quoted

Originally posted by thesmilingassassin
Good point Marek.

From "Warplanes of the Second World War", Fighters, Volume 1, by William Green, Doubleday and Company, Garden City NY, 1960, pp 33 - 34

Prototype construction inaugurated at Villacoublay in December 1939. The GR 14R-4 engine installed in the prototype offered 1590hp for takeoff, 1700hp at 26390 feet and a cruising output of 1,400hp. Prototype was not assembled prior to the German occupation of Paris and the components were to be trucked to Poitiers but the vehicles carrying it were captured and the components taken to Bordeaux-Merignac, where it was assembled for the German authorities. First flown in March 1942, without armament. Ferried to Paris-Orly, where the powerplant was removed for further study and the airframe stored in an airship hangar at Orly. The prototype was subsequently destroyed in an air raid.

Type: Single-seat interceptor fighter
Powerplant: One 1580hp GR 14R-4 14cyl air cooled radial
Armament (proposed): two 20mm HS404 and four 7.5mm MAC 1934
Maximum speed 441mph at 25,750ft, 416mph at 27,890ft, cruising speed 248mph.
Climb to 26,250ft 11 min
Range 680 miles at 19,685ft; endurance 1.5 hrs at 70% power
Weight empty 5,265 lb., normal loaded 7,165 lb.
Dimensions - span 35ft. 1.25 in; length 31ft. 9.75in.; height 10ft.6in; wing area 208.819 sq.ft

Quoted

So there is a chance those figures are correct although there is no information on the state of the MB 157 during those test flights. Without armor, armament and much fuel, hence in light weight condition, she might have been able to reach high speeds at altitude.

Its a case of "maybe" but the performance seems pretty unlikely for a production version.

Hooman is indeed right about the 710 KM/H! I've here a Dutch book whish told me the same, but the Aircraft never come on production!