Kawasaki Ki-61 "Tony"Part 3
 
Topics:
Spiral spinnered Ki-61
Need help on some photoes
Ki-61s at Vunakanau, Oct, 12, '43
Ki 61 cowl guns
Spiral spinnered Ki-61
 
Posted By: Ryan Boerema <ryann1k2j@aol.com>
Date: Tuesday, 30 July 2002, at 6:07 p.m.
 
If anyone has it, p. 66 of Watanabe's "Army Fighter Ki-61" of which a kind J-Aircraft reader sent me a scan, shows a bunch of slightly ill at ease looking Japanese, none of which are in pilot gear, but some with pith helmets, standing in front of a Tony that seems to have a dark propellor boss with a white spiral, a la Luftwaffe bird and AA gunner confusing style. I can't read the kanji below the picture, but note the sentai ideogram (a stick figure with a bad haircut) only once, and that not prededed by a number: my usual method of partial decipherment.
Now, here's the long shot.
IF, anyone has this book and can read the text could you pass the translation along? We've been trying to figure out its location by surmise and guesswork.
 
Re: Spiral spinnered Ki-61
 
Posted By: Hiroyuki Takeuchi
Date: Thursday, 1 August 2002, at 3:43 p.m.
 
In Response To: Spiral spinnered Ki-61 (Ryan Boerema)
 
This is the 68th Sentai enroute to New Guinea aboard the carrier Taiyo.
 
 
Need help on some photoes
 
Posted By: Larry Bishop <dak57@comcast.net>
Date: Saturday, 27 July 2002, at 5:30 p.m.
 
I have 3 photoes from a Japanese website that I would like to scan and send them to some one who could post them on this site, so the units may be identified.
 
Can anyone ID this unit *PIC*
 
Posted By: Larry Bishop <dak57@comcast.net>
Date: Monday, 29 July 2002, at 12:05 p.m.
 
In Response To: Need help on some photoes (Larry Bishop)
 
Image from the 244th website
 
Editors note: Picture at http://www5b.biglobe.ne.jp/~s244f/album037.jpg
 
Re: Can anyone ID this unit
 
Posted By: Ryan Boerema <ryann1k2j@aol.com>
Date: Monday, 29 July 2002, at 1:37 p.m.
 
In Response To: Can anyone ID this unit *PIC* (Larry Bishop)
 
FAOW #17 says 11th Special Attack unit, 5/45, ModelArt #428 says 11th Flight Regiment at Metachibara A/B, Saga Prefecture, same date, and identifies it as a Ki-61D.
 
Re: Can anyone ID this unit #2 *PIC*
 
Posted By: Larry Bishop <dak57@comcast.net>
Date: Monday, 29 July 2002, at 12:08 p.m.
 
In Response To: Can anyone ID this unit *PIC* (Larry Bishop)
 
Does any one know what the white markings are in front of the hinomaru?
 
Editors note: Picture at http://www5b.biglobe.ne.jp/~s244f/album5059.jpg
 
Re: Can anyone ID this unit #3 *PIC*
 
Posted By: Larry Bishop <dak57@comcast.net>
Date: Monday, 29 July 2002, at 12:11 p.m.
 
In Response To: Re: Can anyone ID this unit #2 *PIC* (Larry Bishop)
 
Anyone the unit of the Dinah in the pic? What are the colors?
 
Editors note: Picture at http://www5b.biglobe.ne.jp/~s244f/album7075.JPG
 
 
Ki-61s at Vunakanau, Oct, 12, '43
 
Posted By: Ryan Boerema <ryann1k2j@aol.com>
Date: Monday, 22 July 2002, at 12:58 a.m.
 
Where they pretty much weren't supposed to be, having moved to the Wewak area during July '43. Yet p.57 of Lawrence Hickey's "Warpath Across the Pacific" shows one of those nifty low level attack photos of three Tonys of the 68th Sentai in revetments at the east end of the runway, one apparently a chutai commander's a/c, during the 345th's attack of October 12th, 1943. There is also text of one further taxying Tony being shot up, and mention of a Dinah and a Helen at the same location and a Lily at Rapopo.
So, what do you think they were doing there? Accounts of Tonys out of the Rabaul area after summer '43 have been generally pooh-poohed as misidentification in the heat of battle, and I know all a/c were used for liason of some sort during the war, but four Tonys (possibly more?) seems a goodly number. Any guesses?
And while I'm asking questions, how the heck did the 5th AF so successfully surprise the Wewak complex during the August '43 raids. Didn't the Japanese have radar? Weren't there Japanese emplacements well before Boram or in the Markham and Ramu valleys that would report in such large formations of a/c? I know there were investigations into the destruction of the JAAF in New Guinea, anyone know what was concluded?
 
Re: Ki-61s at Vunakanau, Oct, 12, '43
 
Posted By: Henry Sakaida
Date: Friday, 26 July 2002, at 8:05 a.m.
 
In Response To: Ki-61s at Vunakanau, Oct, 12, '43 (Ryan Boerema)
 
I'm doing a magazine article on Pappy Boyington's last dogfight and found that 2 Tonys were claimed shot down over Rabaul, on 3 January 1944!!! How can you mistake a Zero for a needle-nosed Tony??!!!
 
I have also finished our book on the 343 Kokutai, which flew Shiden-Kais. In their baptism of fire, they fought VBF-17 over Iyo Nada (Inland Sea) on 19 March 1945, and some of the VBF-17 pilots claimed Tonys, when there were none!!! Go figure!!
 
On 28 May 1945, we interviewed a Shiden-Kai pilot who claimed that they were ambushed by P-51 Mustangs, when in fact, they were P-47s!!! How can you mistake a Mustang for a Thunderbolt??!!!
 
I think in a dogfight, you just see a flash of the enemy, and if your first thought was a Tony, then true or not, that becomes burned into your memory.
 
Most of the Tonys at Rabaul left for New Guinea, but there were a few left behind. Perhaps 1 or 2 actually flew, thus adding to this confusion. When the JNAF 253 Ku pulled out of Rabaul on 18-20 February 1944, they took all airworthy Zeroes with them to Truk. They left behind Zeroes with engine problems which couldn't make the flight. The mechanics there rebuilt Zeroes from the scrap heap, and soon, they had 7 - 8 flyable Zeroes! I think the JAAF mechanics must have rebuilt a few Tonys, because they had the wrecks and the junked aircraft, and too much time on their hands.
 
Re: Ki-61s at Vunakanau, Oct, 12, '43
 
Posted By: richard dunn <rdunn@rhsmith.umd.edu>
Date: Monday, 22 July 2002, at 5:53 a.m.
 
In Response To: Ki-61s at Vunakanau, Oct, 12, '43 (Ryan Boerema)
 
14th Air Depot as still active at Rabaul until the end of November 43. Rabaul was a repair and rear area training base for the JAAF until the Oct 43 raids.
 
Two radar sets arrived at Wewak in April 43. As of August 43 they were still not operational. Some of the August raids were picked up and reported by the JAAF air intelligence units. However, reporting of the August 17th raid and others where heavy damage was inflicted was obviously inadequate to say the least.
 
Re: Ki-61s at Vunakanau, Oct, 12, '43
 
Posted By: Ryan Boerema <ryann1k2j@aol.com>
Date: Tuesday, 23 July 2002, at 3:18 p.m.
 
In Response To: Re: Ki-61s at Vunakanau, Oct, 12, '43 (richard dunn)
 
Thanks, Richard, you always have the answers, howsoever prosaic. History just keeps throwing these teasers at me. For instance, Osprey's A/C of JAAF aces, by Henry Sakaida, #13, quotes Susumu Kajinami, with the 68th at Wewak from August '43 to February '44, as having shot down, along with USAAF A/C, two F4Us, three F6Fs, and one F4F! But I suppose I could just as rationally look for evidence that Wildcats fought over Wewak....
 
Ki 61 cowl guns
 
Posted By: Rob Brown <rbrown1553@earthlink.net>
Date: Friday, 19 July 2002, at 10:26 a.m.
 
Can anyone tell me which Tony did not have the cowl mounted weapons.
 
Re: Ki 61 cowl guns
 
Posted By: Tony Williams <Tony.Williams@quarry.nildram.co.uk>
Date: Friday, 19 July 2002, at 12:48 p.m.
 
In Response To: Ki 61 cowl guns (Rob Brown)
 
Well I don't, though it's an intriguing thought :)
 
Seriously, Francillon says they all had them...
 
Re: Ki 61 cowl guns
 
Posted By: jackson <FincherI@aol.com>
Date: Friday, 19 July 2002, at 2:16 p.m.
 
In Response To: Re: Ki 61 cowl guns (Tony Williams)
 
One of the Hasegawa Type 3 Tonys calls for the cowl gun openings to be filled in. This is the "shamrock" marked aircraft allegedly flow by Capt Ichikawa, 244th Sentai. I'm assuming if this was the case it was done as a weight saving measure...
 
Re: Ki 61 cowl guns
 
Posted By: Tony Williams <Tony.Williams@quarry.nildram.co.uk>
Date: Friday, 19 July 2002, at 10:39 p.m.
 
In Response To: Re: Ki 61 cowl guns (jackson)
 
That seems odd, since the cowl guns seemed to be favoured in terms of calibre - they were the first to get the 20mm Ho-5, for instance, with the wing guns following later. As a matter of interest, what wing guns were fitted to this aircraft?
 
Re: Ki 61 cowl guns
 
Posted By: Rob Graham - the ReiShikiSenGuy
Date: Sunday, 21 July 2002, at 6:51 p.m.
 
In Response To: Re: Ki 61 cowl guns (Tony Williams)
 
I would think it would be more than just weight savings here, as I think the "Sham Rock" Hien was for Tokkotai and all the weapons would impede performance.
 
I've read the B-29 left an incredible wash of air at altitude, and aircraft like the Zero had a very hard time flying in the rarefied air because the engine had too little oxygen and the propeller and wings had too little atmosphere to "grab." I'd guess that any performance gains, no matter how slight, would be very important.
 
Re: Ki 61 cowl guns
 
Posted By: jackson <FincherI@aol.com>
Date: Saturday, 20 July 2002, at 5:47 a.m.
 
In Response To: Re: Ki 61 cowl guns (Tony Williams)
 
They don't specify other than the generic 2 x 20mm and 2 x 12.7 mm. So I can only assume the wing guns are 12.7mm. If this is the case it kind of flies in the face of conventional wisdom, although I do have other sources that show 20mm cannon mounted in the wings and a pair of cowl mounted 12.7mm weapons (KI-61 Ia and KI-61 IIa) and a KI-61 IIb with 4 HO-5 cannon.
 
I guess it's time to put it out to our esteemed panel.
 
Re: Ki 61 cowl guns
 
Posted By: Ted Bradstreet <tbstreet@midmaine.com>
Date: Thursday, 25 July 2002, at 1:15 p.m.
 
In Response To: Re: Ki 61 cowl guns (jackson)
 
As I've said before, I'm not on top of aircraft variants, but here's a caution. All Browning guns are slowed in cyclic rate considerably by synchronization. Ho-103's in Ki-43's were reportedly slowed to the point of virtual uselessness.
 
Despite the caliber, it is not clear to me how effective cowl-mounted Ho-5's would be. Contrary to their paper specs, aircraft listed as having cowl-mounted synched guns often did not use them in service. A big-bore gun that goes "BANG-waitforit-waitforit-BANG-waitforit--" doesn't hit much in aerial combat. It was a commonplace to lose the cowl guns first in a search for better handling/lower all-up weight.
 
Re: Ki 61 cowl guns
 
Posted By: Tony Williams <Tony.Williams@quarry.nildram.co.uk>
Date: Thursday, 25 July 2002, at 1:30 p.m.
 
In Response To: Re: Ki 61 cowl guns (Ted Bradstreet)
 
It's puzzling that the synchronisation system performed so badly. I'm not sure which system the Japanese used (presumably the IJA and IJN chose different ones...) although they did adopt the British CC hydrosonic system after WW1. This was supposed to be capable of dealing with rates of fire of up to 1,200 rpm, with two firing opportunities per propeller revolution.
 
As the Ho-103 was capable of only 900 rpm unsynchronised, the RoF loss shouldn't have been too severe. Possibly there was a problem with the relationship between the RoF and propeller revolutions.
 
Re: Ki 61 cowl guns
 
Posted By: Mike Goodwin <Mike.Goodwin@bigfoot.com>
Date: Friday, 26 July 2002, at 7:55 a.m.
 
In Response To: Re: Ki 61 cowl guns (Tony Williams)
 
Tony's engine had rated rpm of 2,500 and 2,400, and reduction gear ratio was 0.635. All Tony variants had 3-blade propellers, so there would have been a firing gap just over 4,500 times per minute. I don't know anything about interruptor mechanisms, how would this pan out in terms of rof? If a shot was fired into each 5th gap, that would be about 900 rounds per minute, but would it have set up bad vibrations? Or a shot through each 6th gap would give 750
 
Re: Ki 61 cowl guns
 
Posted By: Ted Bradstreet <tbstreet@midmaine.com>
Date: Friday, 26 July 2002, at 9:10 a.m.
 
In Response To: Re: Ki 61 cowl guns (Mike Goodwin)
 
Now we're getting to the meat of the problem. Neither 900 nor 750 rpm is a good match to the "natural" rof of the Ho-5 (IIRC), which means the compromise rate will be something much less, and something under 600 rpm was just not useful. In the Ho-103 example the reduction was from 900 rpm to around 400 rpm, effectively putting the cowl guns out of commission.
 
The problem has to do with the firing mech of the Browning, not the synch mech. Where are the Brownings in most US/Brit fighters? Ever wonder why?
 
Re: Ki 61 cowl guns
 
Posted By: Emmanuel Gustin <Emmanuel.Gustin@skynet.be>
Date: Friday, 2 August 2002, at 4:37 p.m.
 
In Response To: Re: Ki 61 cowl guns (Ted Bradstreet)
 
Part of the reason for putting the guns of US and British fighters in the wings is that you can't fit six or eight guns, with ammunition boxes and eject chutes, in an aircraft's nose. There just isn't enough room, and the c.g. effects of ammunition consumption would be unpleasant. AFAIK nobody has successfully synchronised more than four guns.
 
The British did want eight 1000 rpm guns, so synchronisation was excluded from the start.
 
But I don't see why the American Browning, which AFAIK fired from a closed bolt and therefore had to have a separate striking pin release, wouldn't be suitable for sychronisation? The timing ought to be accurate.
 
I know that the British modified the .303" to fire from an open bolt to avoid cook-offs. Did the IJA perhaps modify their guns to fire from an open bolt? It does seem a safer practice with HE ammunition.
 
Re: Ki 61 cowl guns
 
Posted By: Tony Williams <Tony.Williams@quarry.nildram.co.uk>
Date: Saturday, 3 August 2002, at 12:40 a.m.
 
In Response To: Re: Ki 61 cowl guns (Emmanuel Gustin)
 
When the British modified the Browning to fire from an open bolt, they retained the separate striker control so that the gun could still be synchronised (as it was in the Gladiator), so I doubt that was the explanation.
 
Re: Ki 61 cowl guns
 
Posted By: Tony Williams <Tony.Williams@quarry.nildram.co.uk>
Date: Friday, 26 July 2002, at 11:34 p.m.
 
In Response To: Re: Ki 61 cowl guns (Ted Bradstreet)
 
There were some US tests which add further information. This is from my next book:
 
"A practical example of the effect of synchronisation is graphically provided by comparative tests held by the USN in 1926/7 of the .30" M1921 and .50" M1921, both on a test stand and in synchronised mountings. These also shed some light on the differences between claimed and actual rates of fire, and between different installations of the same gun. The .30" had a claimed RoF of 1,200 rpm, but proved capable of between 800 and 900 rpm on the test stand. When synchronised, the RoF went down to an average of 730 rpm (a fall of about 15%), with a range of between 667 and 818 rpm for different installations and propeller speeds. The .50" had a claimed RoF of 600 rpm, and did rather well to achieve between 500 and 700 rpm, depending on the recoil buffer adjustment (although a contemporary British report put this at 400-650 rpm, the difference possibly caused by belt drag when installed), but this fell to an average of 438 rpm when synchronised, varying between 383 and 487 rpm. As the synchronised guns were adjusted for maximum RoF, this represented a reduction of around 37%. There is no inherent reason why a larger calibre weapon would suffer a bigger reduction in RoF, so the synchronisation conditions must have been better suited to the .30" gun's natural RoF."
 
This situation still existed in 1940, as the British tested a US plane (I forget which - a Curtiss I think) with synchronised .50s and grumbled about the 400-450 rpm RoF.
 
This is a complex subject which I have been trying to get to grips with. Synchronisation systems (incidentally they weren't technically "interrupter systems" although they were often called that - synchronised guns were effectively semi-auto, and fired one shot each time they were told to by the synch gear) did not necessarily provide one shooting opportunity for evey gap between blades, sometimes it was only one per prop rev, but this information is very hard to find.
 
Before constant-speed props were used, the RoF of a synchronised gun fluctuated with prop revs. For example, if the gun could fire at 1,000 rpm and there was one shooting chance per prop rev, then at propeller rpm up to 1,000, the RoF would be the same as the revs. At 1,010 rpm, however, the gun would have to miss every other chance and the RoF would drop suddenly to 505 rpm. So, the type of propeller fitted, and the way its gearing operated, was a crucial factor as well.
 
It is certainly true that the gun mechanism was influential. Some types of weapons just couldn't be synchronised because the control of the sear release wasn't precise enough, usually because they fired from an open bolt (the Lewis gun and all the Oerlikon family are good examples). The Browning fired from a closed bolt, though, so that shouldn't be a major factor. There is also the point that the USA selected the Browning over other aircraft guns at a time when all fighter guns were synchronised, so it seems unlikely that the Browning was so much worse than the others.
 
If anyone out there is able to provide an explanation for the problems suffered by the synchronised Brownings, I would be interested to hear it!
 
Re: Ki 61 cowl guns
 
Posted By: Emmanuel Gustin <Emmanuel.Gustin@skynet.be>
Date: Friday, 2 August 2002, at 3:53 p.m.
 
In Response To: Re: Ki 61 cowl guns (Tony Williams)
 
on the subject of the P-51's synchronised guns, Francis H. Dean writes that they "were not be fired under 1000 and above 3000 [engine] rpm." It doesn't sound like much of a limitation given that the engine was rated at 3000 rpm max, but higher speeds were permitted in a dive, and were also achieved by raising the boost pressure in the field.
 
The synchronisation gear is called an "impulse tube synchronisation system" which sounds like a hydrosonic system to me. The P-39 / P-63 installation differed mainly in that the gear was not driven from the engine, but from the reduction gear box in the nose.
 
The US Navy appears to have used an electrical gear on the F2A, connected to the trigger solenoid. (Not as good, therefore, as the German system of electrical ammunition priming.)
 
Re: Ki 61 cowl guns
 
Posted By: Ted Bradstreet <tbstreet@midmaine.com>
Date: Monday, 29 July 2002, at 7:42 a.m.
 
In Response To: Re: Ki 61 cowl guns (Tony Williams)
 
I'm working on it. (Remember too, synched Brownings in US service were .30's.) I think this thread has gotten way off the initial subject and we should probably go private e-mail with the rest. Not too much here in revelations for general Japanese aircraft interests.
 
Re: Ki 61 cowl guns
 
Posted By: jackson <FincherI@aol.com>
Date: Monday, 29 July 2002, at 10:52 a.m.
 
In Response To: Re: Ki 61 cowl guns (Ted Bradstreet)
 
Don't forget the main battery in P-40B's were a pair of 50cals firing though the cowl(hello Flying Tigers) and even earlier biplane fighters had the option of replacing one of the cowl mounted 30 cals with a 50 cal weapon. How about the P-39's. Many Soviet aces that flew them never mounted the wing weapons ala Mig/LaGG/Yak. Let's muddy the waters a bit... every Soviet produced fighter that I'm familiar with during WWII had all their weapons mounted in the cowl or prop hub...usually a mix of machineguns and cannons. How did they suceed against the creme of the Luftwaffe with just fuselage mounted weapons?
 
Speaking of Luftwaffe..a number of FW-190 and Bf-109 varients had heavy cal machine guns mounted in the cowl. Some Bf-109 (F/G/K )varients had no provision for wing mounted weapons other than those slung under the wings. These guys achieved success...even against 4 engine bombers and the some of the best the USAAF threw at them.
 
I would imagine that the biggest advantage to having the battery moounted in the fuselage would be the concentration of firepower available at any effective range(remember Bong/McGuire in P-38's).
 
Sounds like Japanese industry did their aviators a diservice if the y failed to develope similar technology..
 
Re: Ki 61 cowl guns
 
Posted By: Ted Bradstreet <tbstreet@midmaine.com>
Date: Tuesday, 30 July 2002, at 8:01 a.m.
 
In Response To: Re: Ki 61 cowl guns (jackson)
 
German and Soviet synchronized guns a) were most assuredly not Brownings and b) were designed from the outset for sychronization, particularly the MG 17. This is not a discussion of the effectiveness of cowl guns in general, but of the effectiveness of synchronization of a particular large-caliber Browning, the Ho-5. It is already established that a) synchronization is not kind to Brownings and b) that the problem gets worse as the caliber increases, most probably due to increased mass of moving parts. This seems to be related to the so-called "timing" of Browning guns, but I need to do more research.
 
Re: Ki 61 cowl guns
 
Posted By: Tony Williams <Tony.Williams@quarry.nildram.co.uk>
Date: Monday, 29 July 2002, at 10:15 p.m.
 
In Response To: Re: Ki 61 cowl guns (jackson)
 
Fuselage mounted guns do have the advantage of concentrated fire at all ranges, whereas wing-mounted guns only concentrated their fire around the range they were harmonised for. So a fighter with fuselage-mounted guns needed fewer of them for the same general effectiveness.
 
The best position for a fighter gun was only available to those with V-12 engines (and not all of those, depending on the engine design and installation): that is, mounted between the engine blocks to fire through the hollow propeller hub. No problems with synchronisation. The Russians and Germans used this wherever they could, the Japanese, British and Americans did not (except for the special case of the P-39/63).
 
The Russian 12.7mm Berezin was most commonly cowling mounted and synchronised. RoF dropped from 1,050 to 800 - about the same as the comparable .50 unsynchronised.
 
The German electrical synchronisation system was the best (especially when combined with electrical priming, as with the 13mm MG 131 and 20mm MG 151). This reduced the RoF by only around 10%, which explains why they were happy to use synchronised guns. It is notable that when ground attack versions of the Fw 190 needed to lose a couple of their 20mm to save weight, it was the outer wing (unsynchronised) ones which went, not the wing root (synchronised) ones.
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