Mitsubishi Ki-51 SONIA
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Mitsubishi Ki-51 SONIA

To meet an Imperial Japanese Army specification of December 1937 for a ground-attack aircraft, which it was suggested could be a development of the Ki-30 light bomber, Mitsubishi produced two prototypes under the designation Mitsubishi Ki-51. Of similar external appearance to the Ki-30, the new design was generally of smaller dimensions, had a revised and simplified cockpit that put the two-man crew more closely together and, because the bomb bay was not required, the monoplane wing was moved from a mid- to low-wing configuration. Powerplant chosen was the Mitsubishi Ha-26-II radial engine, Tested during the summer of 1939, the two prototypes were followed by 11 service trials aircraft, these being completed before the end of the year. They differed from the prototypes by incorporating a number of modifications, but most important were the introduction of fixed leading-edge slots to improve slow-speed handling and armour plate beneath the engine and crew positions. In addition to the standard production aircraft, there were attempts to develop dedicated reconnaissance versions, initially by the conversion of one Ki-51 service trials aircraft which had the rear cockpit redesigned to accommodate reconnaissance cameras. Test and evaluation of this aircraft, redesignated Ki-51a, brought a realization that the standard Ki-51 could be modified to have provisions for the installation of reconnaissance cameras, and this change was made on the production line. Subsequently, three Ki-71 tactical reconnaisance prototypes were developed from the Ki-51, introducing the 1119kW Mitsubishi Ha-112-11 engine, retractable landing gear, two wing-mounted 20mm cannon and other refinements, but no production examples were built.

Allocated the Allied codename 'Sonia', the Ki-51 was used initially in operations against China, and was deployed against the Allies until the end of the Pacific war. In more intensely contested areas the fairly slow Ki-51s were easy prey for Allied fighters, but in secondary theatres, where an ability to operate from rough and short fields was valuable, these aircraft gave essential close support in countless operations. In the closing stages of the war they were used in kamikaze attacks.

Mitsubishi Ki-51 SONIA

 ENGINE1 x Army Type 99 Mod. 2, 705kW
    Take-off weight2798-2920 kg6169 - 6438 lb
    Empty weight1873 kg4129 lb
    Wingspan12.1 m40 ft 8 in
    Length9.21 m30 ft 3 in
    Height2.73 m9 ft 11 in
    Wing area24.02 m2258.55 sq ft
    Max. speed424 km/h263 mph
    Ceiling8270 m27150 ft
    Range1060 km659 miles
 ARMAMENT3 x 7.7mm machine-guns, 200-300kg of bombs

Mitsubishi Ki-51 SONIAA three-view drawing (752 x 1055)

Patrick, 13.04.2014

with the starter-spinner dog shaft truck thingie, many Japanese planes featured that starter set-up, and I got to inspect one close up on the engine crash remains of a Ki46 Dinah they have at the Tindal Darwin air museum in Australia..the weight-saving on not having an electric start and sometimes internal batteries is considerable, especially for aircraft relying on height and speed for defence like the Dinah.

Patrick, 13.04.2014

I'm reading a book non-fiction, about the Japanese WW2 Kamikazes called "Blossoms in the Wind"...(can recommend the hell out of it, too, if you want a highly narrative of memoirs from surviving Japanese Ww2 "Tokko"pilots from a US author with high creds in Japanese language and culture)in it author describes in great detail an --IJA--Army(most Tokko were Navy) "Tokko" unit which was formed at Bacloban on Luzon, and equiped with Ki51s..I realised I'd never consciously heard of a Ki51, and thought he'd confused it with Ki15s, but when I saw the poor quality b/w pic of one of the units planes landing in the book, I realised it was no Ki15 Babs..I'd heard of the Ki30, and thought IT was the code-name 'Sonya"...but Ki30 is the "Ann" and Ki51 which looks almost the same but is a little smaller is the "Sonya" I have been into Ww2 planes since as a child in the 1960s, and Japanese ones were a special favorite with me, but that subtle distinction Ki30 vs Ki51, had slipped past me.
Anyway, after various mishaps in weather and mechanical issues he finally takes off in a Ki51 with bad performing smoking engine and dirty 'Marianas Gas" gasoline, and when within distant sight of a US troop convoy, is jumped by an F6F and forced down.

Phil Kuoni, Maj, USArmy (retir, 01.09.2013

That "thingie" is the connector for a starter shaft inserted from a rig mounted on a truck connected to the truck's motor.. That was the means of starting the motor as compared to explosive cartridges, external starter crank or an external ground starter unit ("putt putt"). The Russians also used this method of starting many of their aircraft. Hope this explains it for you. Phil

Ron Weil, 19.05.2013

Does anyone know what the "thingie" that looks like a cannon protruding from the prop spinner is?

y.k, 13.12.2011

It based on ki30,and ki30 based on ki15.
and ki15 based on A5M.
All of these have same structure and handling property.

Andy, 13.12.2011

Was this based at all on the JU. 87?

beruk, 01.09.2010

You Can Find the only Survivor of this Aircraft in Adisucipto Aviation Museum, Jogjakarta, Indonesia

Ta-183, 16.05.2010

And it was used for kamikaze roles too.

ta-183 Huckebein, 16.05.2010

Im making a short movie today I think i might put that plane in it because it looks cool. (The Movie is a about a renegade japanese pilot that attacks a formation of Australian Bombers)

Frank, 23.10.2009

Could you post horsepower figures (hp) as well as kW for the engine ratings?

Sgt.KAR98, 03.01.2009

Looks a very nice plane.

Freeman, 29.02.2008

Ki-51 wasn't a torpedo-bomber aircraft. It was only light bomber. Sometimes, this planes were used in recon role.

John Doe, 11.10.2007

Is it a Torpeto bombmer?

Al Kretz, 21.04.2007

I build, fly and compete in Radio Control Scale models. How can I obtain more information on the Mitsubishi KI-51 "Sonia"? I need 3-views, pictures and color schemes. Thanks

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