Available WEP time

[lazs]

earlier R2800's used different heads and bearings and the corsair was designed before the Hellcat.  The Hog was designed to run 10 minutes (topped off with water) which seemed safe.  The "c" series engines were better for cooling even though there had been no problems with the earlier engines.   later Hogs use the c series.

The Jug was suppossed to run 12-15 minutes.  It was turbo supercharged and so probly used a higher rate pump for the water.   Jugs often came home with dry water tanks.

All PW R2800's consumed water and fuel depending on engine condition/tune.  It was a simple adjustment to "up" the boost in the PW.   I suspect that the 19 year old hot rodders in the field did this quite often.
lazs

[Jochen]

 

I have already said that the GM-1 tank was available in the A8 as well. The tank was 25.3 gallons. So I guess I do know know what I'm talking about.

Yes, there was possibility to put GM 1 system to A-8 but it required HIGH PRESSURE gas bottles, not a simple fuel tank as you suggest. I would like to see you trying to force high pressure liquid nitrous oxygen to a ordinary thin walled fuel tank.

109's that had GM 1 had to use cylindrical high pressure bottles located on left wing root to contain the gas, why not 190?

There is a myth that A-8 can have either GM 1 liquid, MW 50 liquid or fuel in EXT tank. GM 1 part is roadkille. GM 1 required HIGH PRESSURE gas bottles and that EXT tank is not a high perssure gas bottle.

I'm still not convinced you know what you are talking about.

 

Try reading the thread before criticizing.

If you try not to jump into conclusions without knowing the facts. (ie. F-8 having GM 1 boost, must be lufwaffe conspiracy to get one)

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jochen Gefechtsverband Kowalewski

Units: I. and II./KG 51, II. and III./KG 76, NSGr 1, NSGr 2, NSGr 20.
Planes: Do 17Z, Ju 87, Ju 88A, He 111H, Ar 234A, Me 410A, Me 262A, Fw 190F, Fw 190G.

Sieg oder bolsevismus!

[Jochen]

Of course GM 1 used nitrous oxide, not nitrous oxygen as I stated but english is not my native language.

But I am still very sure that EXT tank in A-8 was not capable of storing GM 1 liquid.

------------------
jochen Gefechtsverband Kowalewski

Units: I. and II./KG 51, II. and III./KG 76, NSGr 1, NSGr 2, NSGr 20.
Planes: Do 17Z, Ju 87, Ju 88A, He 111H, Ar 234A, Me 410A, Me 262A, Fw 190F, Fw 190G.

Sieg oder bolsevismus!

[Jochen]

Just checked two Nowarra's books and they mentioned that Ta 152H carried GM 1 pressure bottles and A-8 EXT tank could be replaced by smaller tank capable holding GM 1 nitrous oxide.

I think case is closed on this one.

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jochen Gefechtsverband Kowalewski

Units: I. and II./KG 51, II. and III./KG 76, NSGr 1, NSGr 2, NSGr 20.
Planes: Do 17Z, Ju 87, Ju 88A, He 111H, Ar 234A, Me 410A, Me 262A, Fw 190F, Fw 190G.

Sieg oder bolsevismus!

[F4UDOA]

Jochen,

I am reading this directly from a book from the Smithsonian press called "FW190 Workhorse of the Luftwaffa" which details a FW190-F8 and has a note on the bottom about the third tank being available on A-7 and A-8 models as well expressly for carrying GM-1.

It was a 25.3 gallon tank. No other mention of the tanks condition(pressurized or unpressurized) is mentioned. Although being only a 25 gallon tank I don't imagine that it would have served much use as a standard fuel tank being so small.

[Jigster]

25 gallons is an enormous amount of Nitrous Oxide...would prolly excede the fuel capacity easily depending on what pressure is used.

Racing NO2, in 1 Gallon bottles last for a duration of 3 hours at 10lb shots, to give you an idea.

- Bess

[Jimdandy]

Here's another thought on the water injection. Wouldn't it also increase charge density and mass flow rate through the engine. Also water in the right amount could act as an oxidizer during combustion couldn't it? Isn't there something similar used on jet aircraft? On the nitros, the only way I've ever seen it stored was in a pressurized bottle. I always assumed it was so in the planes. 25 gal, as Jigster said, is a lot of nitros. I think a 600cid+ engine turning 8000rpm in a dragster will use about 2/3 the amount of nitros as a 1600cid 4000rpm. With that ruff estimate and Jigsters estimate a 25 gal nitros tank will give around 100 hrs of boost time. I'm just ruffing these calculations DON'T PANIC if you think I'm wrong just tell me why. I'm getting so sick of people on here freaking out if you make a SWAG and it's wrong. It's a guess.

PS Jigster = Jeg's maybe?    

[This message has been edited by Jimdandy (edited 01-31-2001).]

[chisel]

Nitrous oxide is used to raise the engines critical altitude. Nothing to do with its use in Dragsters. To my knowlege Fuel systems werent setup to add the extra fuel on the deck.

From Janes: Ta152b (Db603) injected  at 13.2 lbs/min.

Edit; The germans also experimented with pure O2 but I figure it was consided a little too dangerous to haul that much Compressed O2 around  




[This message has been edited by chisel (edited 01-31-2001).]

[Jigster]

Nitrous Oxide does a few things -- namely, when on the compression stroke, when N02 raises above 570 degrees, the molecules break up releasing oxygen. As the NO2 breaks down, it boils to a much lower temperature within the chamber, dropping charge temp way down, providing a more dense air/fuel mixture for more efficent burning. The boiling effect of the NO2 also creates a "steam"-like effect that delievers more power by dampining the effect of the extra fuel burn, yet increases cyclinder pressure creating more power and torque.

GM-1 will work it's best a high altitude where the oxygen can be put to use -- but, don't be fooled into thinking nitrous Oxide doesn't have much effect at lower altitudes. When compared to MW50, GM-1 provides massive power gains (or restoration if you will) at altitude, yet on the deck the MW50 works better for overboosting. But the NO2 does reduce engine temp quite a bit so the super charger works more efficently, but the steam (expansion on vaporization) effect and combustion buffer of menathol/water allows for more power and higher boost.

the GM-1 (or Nitrous Oxide in general) however, does not reduce engine life to any great extent regardless of application because of the tremendous cooling effect.

- Bess

Btw Jim, I have '79 Bronco with a 1 Gallon NOS, 10,000RPM brand.  

[Jimdandy]

Cool Bronco Jigster.

I do think that nitrous and MW will hurt an engine that hasn't got the proper low end (connection rods, bearings, and main bearings) and oiling system. Take a look at my post "Perk engine for the Spit." The Miss Budwiser was able to get 4,000hp out of a RR Griffon. One of the main things they had to improve was the oiling system. Back then (WWII) they didn't have as much knowledge on oiling systems as we have today. Also the quality of the oil they used wasn't as good. It tended to brake down under thermal stresses faster. It is possible that the original designs for these engines never were intended to support that kind of loading. They may not have had time to retool for a new block that would fit the size of main bearings needed for prolonged high rpm and boost. An example in the automotive world is the Pontiac's. They designed the Pontiac bearings to wide to handle rpm's greater than about 5,500. The oil pump couldn't keep up the volume needed to cover that much area at higher rpm. On top of that Pontiac used cast rods. On top of that their lifter galley was weak. Under high rpm the block would flex enough to crack the lifter galley. That's why they made the SD 455. It fixed all of those problems plus added better flowing heads. These are the factors involved in the short duration of use I bet. The piston speed comes into play here. For the old flat head engine with cast rods and dipper cranks you didn't want the piston speed to be greater than 2500ft/min. To find the piston speed (PS) use this formula:

PS= stroke (in inches) X rpm/6. (This will give you PS in ft/min)

I wouldn't be surprised that the piston speed of all of these engines was close to that. I wouldn't be surprised that the were trying to limit the period of time the engine ran at piston speeds higher than 2500ft/min. This would also reduce stress on the oiling system. When ever you increase cylinder pressure the stresses on the rods, crank and bearings go up. On top of that you increasing the rpm. One more thing might be the ability for the top end (cam, push rods, rocker arm) to handle the higher rpm. In a modern "stock" engine the piston speed can safely reach 3500ft/min. Look at what they do to a racing engine to get it to handle higher than stock loads(I'm sure you know). They add 4 bolt mains, steel or aluminum rods, better bearings, Steel crank, cross drill the crank for 360 degree oiling. All of those things were being learned back then.

PS For those that don't know. Steel cranks are added because they aren't as brittle as cast iron. Steel is more flexible. Steel and aluminum rods will absorb more the impact of combustion with out transferring it to the crankshaft. Aluminum is also light so the energy needed to move it is less. The problem is the aluminum rods aren't as durable. That's one of the reasons you see the top fuel cars tearing into there engines ever couple races to change rods. If they don't they get an expensive ride. Even with those precautions they still have them come apart without notice.

[This message has been edited by Jimdandy (edited 01-31-2001).]

[Jochen]

 

I am reading this directly from a book from the Smithsonian press called "FW190 Workhorse of the Luftwaffa" which details a FW190-F8 and has a note on the bottom about the third tank being available on A-7 and A-8 models as well expressly for carrying GM-1.

I did read details from two Nowarra's book about Fw 190 and he said that normal A-8 and F-8 EXT tank could carry MW 50 or normal fuel or be REPLACED by smaller GM 1 bottle system.

 

It was a 25.3 gallon tank. No other mention of the tanks condition(pressurized or unpressurized) is mentioned. Although being only a 25 gallon tank I don't imagine that it would have served much use as a standard fuel tank being so small.

If it carries nitrous oxide it definitely needs to be a high pressure bottle. How much would 25.3 gallon bottle weight if it was made out of high strenght steel to be able to stand the pressure exceeding 1000 PSI? It would weight a lot!

If you have flown AH A-8 you would know that EXT tank is very small and it empties very fast, it is a small one. But it is an internal tank and sometiems made drag inducing external drop tank unneccessary.

Nitrous oxide for dragsters or aenesthetic purposes are stored in high pressure bottles and I am sure it would have been stored in same way in Fw 190, not in a thin walled fuel tank.

Common sense says that you cannot use same tank for storing fuel and high pressure liquid gas.

I say that EXT tank in Fw 190 cannot store nitrous oxide for GM 1. Only few test 190's were equipped with GM 1 and they most propably used similar high pressure bottles as 109's. F-8 definitely did not use GM 1 because GM 1 is intented as high altitude boost and F-8 was a low altitude ground attack plane.

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jochen Gefechtsverband Kowalewski

Units: I. and II./KG 51, II. and III./KG 76, NSGr 1, NSGr 2, NSGr 20.
Planes: Do 17Z, Ju 87, Ju 88A, He 111H, Ar 234A, Me 410A, Me 262A, Fw 190F, Fw 190G.

Sieg oder bolsevismus!

[lazs]

Oh, the P47 carried 30 gallons of water.  F6 was 16 gallons.  Hog was 10 1/2 gallons.
lazs

[Jimdandy]

Damn I'm good some times.   niklas posted some very good info on the Bf190F4 that seems to conferm my assumtion about piston speed being the critical factor in the WEP time.

Bf109F DB601E:

Stroke = 6.3in
Cruising speed = 2300rpm
WEP = 2700rpm

Useing the formula above:

Cruising speed PS = 2415 ft/min
WEP PS = 2835 ft/min

I looks like they are limiting the time the engine runs at piston velocities over 2500 ft/min. I'm assuming that Cruising speed is less than Military. If so I wouldn't be suprised that Military is 2380rpm = PS of 2500 ft/min.

PS If you look at my post on Perk engine for the Spit you will see that the RR Griffon was running a maximum piston speed of just over 3000 ft/min. This shows me that the Griffon was a more modern engine than the DB601E. The piston speed of the Griffon is closer to the modern standard of 3500 ft/min max.

[This message has been edited by Jimdandy (edited 02-06-2001).]

[niklas]

 

PS If you look at my post on Perk engine for the Spit you will see that the RR Griffon was running a maximum piston speed of just over 3000 ft/min. This shows me that the Griffon was a more modern engine than the DB601E. The piston speed of the Griffon is closer to the modern standard of 3500 ft/min max.

[This message has been edited by Jimdandy (edited 02-06-2001).][/B]

Jumo213: 3250 RPM  

Donīt forget that RR engines were always much closer to the limit of stress than german engines. I.E the german analyzed a Merlin X or XX engine and came to the conclusion that it offered a safety factor of  ~1,6. The early JumoA had a safety factor of ~2,4 (crankshaft or other mechanical components, i donīt have the report at home). That means the merlin engines didnīt offer a possiblity to increase power with water-injection, because they were already running very close at the structural limit. That was different for the german engines.

GM-1 is N2O not NO2 afaik

niklas


[This message has been edited by niklas (edited 02-07-2001).]

[Bombjack]

It is not true to say that Rolls Royce engines could not be tuned to produce higher power, as the 'Miss Bud' example demonstrates extreme tuning.

It is also well-documented that Merlin and Griffon engines were both modified to run 150 octane fuel at manifold pressures of up to 25lb, as compared to the standard 18lb on 100 octane fuel. This is directly analagous to the use of water- or methanol/water-injection.

However that the Merlin and Griffon were both far more highly tuned than their German counterparts is undeniable. One only has to compare their specific outputs to see that.

[This message has been edited by Bombjack (edited 02-07-2001).]