Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: MANDOBLE on January 15, 2002, 06:02:38 PM
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Please fill in the ?:
190D9 -> MW50
109G10 -> MW50
190A8 -> Direct petrol injection
P47D30 -> Water Injection
Yak9U -> None
Yak9T -> ?
109F -> ?
109G2 -> ?
N1K2J -> ?
SpitIX -> ?
SpitV -> ?
La5 -> ?
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I had the same question earlier on Mand.. perhaps this link would help..
My Question on WEP devices (http://www.hitechcreations.com/forums/showthread.php?threadid=27140&highlight=kweassa)
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P-38L: Pedals under the pilot seat to help increase rpm.
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Thanks Kweassa, very good thread.
So most of our planes use a simple increase in the throttle above secure limits.
Based on that:
- Historically, didn't max throttle / max rpm in Yak9u or Zeke lead to any engine overheat?
- Planes without a special mechanism to activate the WEP should not have it implemented as something simply switchable (P key) but by some unsecure "range" in the throttle.
Another question: how did it work in the 190D9 with MW50 or P47 with water injection? Do u activate/deactivate the MW50 / water refrigeration independently of the MAN and RPM? Or activating MW50 usage or water injection implied max MAN automatically?
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MANDOBLE is correct if the descriptions of British aircraft I've read are correct. There was a thin wire that blocked the trottle from being advanced to points that would strees the engine. If the need was great enough the pilot would push the trottle through thw wire to achieve higher power.
Saburo Sakai seemed to indicate in his book that his A6M5's engine was overheating in the fighter he had with a Hellcat squadron.
The engine that the N1K2 and Ki-84 used was capable of taking a methanol-water injection at a 50/50 ratio. I seem to recall that one of those aaircraft was equipped with a tank for it, at least in some cases.
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Karnak, wasn't that the origination of the word/command "buster"?
When the need for speed was there, didn't BOB controller's say "buster" to indicate that pushing through the safety wire was suggested?
Dim memory of reading this somewhere.
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You've missed out the Ju-88.
There were high altitude recon versions with NOX fitted.
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According to "Warplanes of the Luftwaffe" the 109G2 was fitted with the DB 605A-1 engine w/GM-1 power boost.
It also suggests that all version of the 109F used the DB 601E engine, although I don't think that's correct. "Messerschmitt Bf 109 in action, prt 2" indicates that the early versions (109F-0 and F-1) used the DB 601N engine due to unavailability of the E version. More importantly This book notes that with the 109F's use of the GM-1 power boost was indicated by the /Z designation. They mention the 109F-2/Z and 109F-4/Z specifically. It doesn't indicate any other power boost for the non-/Z versions.
Insofar as the Spits go I cant find anything specifc there on boost. "Spitfire in action" notes that the Spit V used several different engines (Merlin 45, 46, 50, 50A, 55, 56 and the 45M, 50M and 55M...the "M" versions being fitted with neg-G carbs and fuel de-aerators). No mention of boost capabilities though. For the Mk IX the same thing...engine types (Merlin 61, 63, 66, and 70) but no specifics on power boost. Perhaps someone has some detailed info on these engines? Afraid I don't.
Regarding the Yak9T, I believe it had the Klimov M-105PF-3 engine as that was the standard version used in the 9D. As far as I know the 9T was basically a 9D with the cockpit moved back to accomodate the breach of the 37mm cannon. Can't offer anything on the issue of power boost here either unfortunately.
Vortex
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Vortex:
Belive it's Bf 109G-1 that has the GM-1 and other high alt gear, but otherwise being identical to the G-2.
// fats
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Believe you're right fats. From what I'm reading here they seem to indicate that the only difference between the G-1 and G-2 was that the latter didn't have the pressurized cockpit.
Vortex
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Arent the boost systems independent of the MAN? That is, could a 109 pilot activate GM-1 with his throttle at half way and, while using GM-1 move the throttle at desire? same with petrol/water/methanol injections?
A more precisse example:
109G10 100% MAN and max rpm. Its engine starts to overheat and then the pilot has two options:
1 - keep max power and activate MW50 to slowdown the overheating.
2 - Ease throttle and activate MW50 to speed up the cooling of the engine.
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The MW-50 was activated with a switch in the instrument panel. To engage it, the pilot had to move the throttle to the "Start u. Notleistung" position (or 110% position), known in AH as WEP. To disengage, throttle back to max nominal position ("Steig u. Kampfleistung" or 100 %). So only MW 50 if you have engaged max power setting.
The GM1 was activated just pressing a switch, but all references I have seen had it only in the "Steig u Kampfleistung" position (100%).
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Originally posted by MANDOBLE
Please fill in the ?:
190D9 -> MW50
109G10 -> MW50 if B4 + MW 50, none if only C3 (DB 605DB)
190A8 -> Direct petrol injection
P47D30 -> Water Injection
Yak9U -> None
Yak9T -> ?
109F -> ? extra hp from engine (110%)
109G2 -> ? none, WEP initially banned by Daimler Benz and not reinstated until June 1943
N1K2J -> ?
SpitIX -> ?
SpitV -> ?
La5 -> ?
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Hi everyone,
Some information on the operation of GM-1:
Since GM-1 served as an oxydizer, activation did immediately result in a fixed power increase by, say, 300 HP, regardless of throttle setting. If the engine was turning too slowly when power jumped up by 300 HP, very high forces on the piston rods would result that could damage the engine. Accordingly, use of GM-1 was only permitted at high RPM.
To be accurate: From the data I've seen, GM-1 power settings were actually a bit below WEP RPM. I think the reason is that since GM-1 is an oxydizer and doesn't need the engine to crank the supercharger at full speed to pump air for combustion, making for a different optimum RPM setting. After all, the greatest benefit from GM-1 is achieved at very high altitude, were reducing propeller speed will result in a reduction of the power loss to Mach effects.
In practice, GM-1 addition was typically achieved by two differently sized injection jets that could be used either singly or seperately to provide, say, 80 g/s, 120 g/s or - if combined - 200 g/s of GM-1 injection. (As Niklas pointed out, GM-1 gave about 3.6 to 3.9 HP for each g/s of N2O flow.)
I guess the pilot had to push the throttle open and then select the desired GM-1 flow rate. With MW50, there was a single activation switch, and if it was activated, MW50 was added whenever the throttle was against the forward stop. I guess it was the same for GM-1 - except that the activation switch probably had several positions for flow rate selection, of course.
MW50 and GM-1 were compatible and could be used simultaneously but as far as I know, only the Ta 152H combined both systems in one airframe. MW50 was mainly used at low altitude and GM-1 up high, but there was an altitude range in between where both systems could be engaged for maximum emergency power.
Regards,
Henning (HoHun)
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Originally posted by MANDOBLE
- Historically, didn't max throttle / max rpm in Yak9u or Zeke lead to any engine overheat?
- Planes without a special mechanism to activate the WEP should not have it implemented as something simply switchable (P key) but by some unsecure "range" in the throttle.
Agreed the Yak3 and 9U was rated to run continuously at what was preveiously considered "augmented power" we call it WEP.
Hence there is no WEP on these planes. The la 5FN and La7 were able to use augmented power (running at 2500 rpm instead of 2400) for limited periods (10 Mins). Such augmented power was only available below 8500 ft above which the first stage of boost was introduced and the extra revs gave no return.
Infact the ASH 82 FNV in the La 7 had a 30 sec rating at 2600 where it reportedly returned 2000hp at sea level. (1850hp @ 2500rpm, 1600/1650 @ 2400rpm).
The periods were for the guidance of pilots. There were no timers or controls as such. It would be more accurate to allow engine damage due to overheat for excessive use of WEP (via throttle). What we have now is a game play conssesion to stop us damaging the engine (it switches off WEP when the engine gets hot)
Tilt
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Hi Tilt,
>Infact the ASH 82 FNV in the La 7 had a 30 sec rating at 2600 where it reportedly returned 2000hp at sea level. (1850hp @ 2500rpm, 1600/1650 @ 2400rpm).
Thanks for the information! Was the Ash 82FNV used in the La-5FN, too? With regard to the La-7: Did every La-7 built use the FNV, or were there FN-powered variants too?
>The periods were for the guidance of pilots. There were no timers or controls as such.
Quite interesting! The DB601A had (in addition to the 5 min WEP rating) a special 1 min WEP rating that was enforced by a timer switch. Different design philosophy, I'd say :-)
By the way, the German WW2 jet engines had short-duration emergency ratings as well: The BMW 003E used in the He 162A-1 for example could be boosted from its normal 265 kp thrust to 332 kp for 30 s (values for 11000 m/800 km/h). Heinkel's endurance caluclations assumed 6 bursts of 30 s emergency power each: At sea level, this would result in a total of 28 min flight time :-)
Regards,
Henning (HoHun)
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WEP time limits (at least for US/UK planes) had a lot more to do with engine overhaul intervals than overheating. Engines could be run at WEP longer than the specified time without immediate consequence. But exceeding the specified times could reduce life of some engine parts. AH enforces time limits and makes us fly "by the book". As a result in AH we have less WEP time than could be acheived in a real life emergency.
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Originally posted by HoHun
Hi Tilt,
Thanks for the information! Was the Ash 82FNV used in the La-5FN, too? With regard to the La-7: Did every La-7 built use the FNV, or were there FN-powered variants too?
Hi Hohun
I believe the first run of La7's trialed in combat did have the FNV but certainly a few used older FN units. Likewise as the La5 fuselages were used up some of the later (june/july 44) units had FNV engines fitted. (many late La5FN's had La7 main wing sparsbut still had the shorter prop and undercarriage)
The FNV super charger was better suited to slightly higher altitudes than the FN but only by a 1000 feet or so higher. It was also suited to a booster linked to an automatic thermo regulater. However this was not properly incorporated until May45, until when boost pressure and temperature was a manual balancing act between throttle and the ventilation vanes. The La7 was the first LA to incorporate automatic pitch control but this was very poor in comparison to the units incorporated in Tanks designs.
Tilt