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What if...General Motors was forced to fix the V-1710?


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#101 Flo

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Posted 05 May 2012 - 07:08 PM

can you please link to, quote or offer some plausible formulae to support your assertion. I'm not an expert on aviation, I'm not a pilot, but I do read an unhealthy number of reference books and memoires. I've never come across an account by an Allied or Axis pilot to the effect that they used 15% lower throttle openings when over enemy territory.
I'd be very interested to read who did, where they did it and what their rationale for doing it was.

#102 Edgar Brooks

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Posted 05 May 2012 - 08:27 PM

maybe the discussion can continue, and your education will show some signs of improvement.

Edited by Edgar Brooks, 12 May 2012 - 06:19 PM.


#103 curmudgeon

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Posted 06 May 2012 - 01:08 AM

"Cruising around" isn't a lot of use, if you've used up your fuel, and had to land to refuel, just as another raid develops; there were times when Kesselring sent fighter-only sweeps, to engage Fighter Command, and clear the way for a following bombing raid, but, thankfully Park was far too smart for that game, and mostly avoided the bait. It seems that, just as the Germans didn't realise how vital radar was, they also didn't realise that we were capable of judging the speeds of the radar returns, and a fast-moving return = fighters only, so leave it alone.

1) As did the RAF on 'rhubarbs' over Northern France. RE Jones was challenged over the German 'bomb-detecting radar', and it took careful (and likely persistent) questioning to establish the RAF error ...
2) Chain Home used a different (and much more primitive) method than German radar ... they used time to return to measure distance and then used distances from adjacent transmitters to generate position. Because of this the zeppelin spy missions only detected these as 50Hz noise (they were using the National Grid to keep things in phase).
3) the key to RAF operations was the ground control (contra the opinion of Douglas Bader ... )

#104 GregP

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Posted 06 May 2012 - 01:18 AM

Reference post # 94.

C'mon Neo, you said the Spits could use full throttle over England and the Germans could not, and the roles were reversed over the channel, presumably over Germany.

Not true. The Germans could and did use full throttle, but not for very liong. If they engaged in a dogfight, they had about 10 minutes before needing to disengage and RTB. Dogfighting for 5 or 10 minutes is not anywhere near the same as not being able to use full throttle.

When the Allies started moving toward Germany after crossing the channel, the Spitfires bases went with them and the Spits were NOT throttle restricted. They planned their missions with allowances for combat.

I don't pretend to know where you come up with this stuff, but is not true.

Edited by GregP, 06 May 2012 - 01:21 AM.


#105 Ricky

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Posted 07 May 2012 - 09:17 AM

I'm actually amused that in one topic you are claiming that the Spitfire was rubbish because it didn't do well when fighting across the Channel (a wrong argument, but never mind) and in this topic you are claiming that Sppitfires were deliberatelt hobbled when fighting across the Channel (a wrong argument, but never mind).

:D

#106 NeoConShooter

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Posted 07 May 2012 - 10:53 PM

[quote name='Edgar Brooks'][quote name='NeoConShooter']Over England the RAF's SOP was to cruise around at 75% throttle looking for trouble. That is a more than 25% advantage and it was because they were NOT worried about the trip home./QUOTE]
Which underlines my assertion that you make up the vast majority of what you write, with what happens to enter your head at any one time, and have absolutely no idea of the conditions that pertained at the time (there was no "SOP" whatever that is); Fighter Command was never able to "cruise around looking for trouble." They were expected to get off the ground, and climb, as hard as possible, to get to a height at which they could engage the enemy.
"Cruising around" isn't a lot of use, if you've used up your fuel, and had to land to refuel, just as another raid develops; there were times when Kesselring sent fighter-only sweeps, to engage Fighter Command, and clear the way for a following bombing raid, but, thankfully Park was far too smart for that game, and mostly avoided the bait. It seems that, just as the Germans didn't realise how vital radar was, they also didn't realise that we were capable of judging the speeds of the radar returns, and a fast-moving return = fighters only, so leave it alone.
As any number of pilots have said, they never got time to achieve a height advantage, and always started the fight with the escorting fighters still above them. The sequence was "Scramble," then, when airborne and still climbing, ask for (and receive) a heading (or landmark) and "Angels" to achieve as quickly as possible. There followed an interception course (hopefully the enemy didn't veer,) still at full throttle, then straight into the attack (maximum 5 minutes permitted,) then a return home. On the Spitfire I each fuel tank had its own cock and gauge, so keeping tabs on fuel consumption wasn't too difficult.
When (if) you can show that you have some grasp of what things were really like, here, at that time, maybe the discussion can continue, and your education will show some signs of improvement.[/QUOTE]

You just made my point exactly!:eek: The RAF used full or METO power almost all the time they were in the air. That means that most missions were tanks dry in much less than one hour. It did not bother the RAF because they were over their home ground.

The Nazis on the other hand, had to fly all the way to and from Southern England. In order to get to and from the coast of Southern England from Northern France, they had to cruise for most of the flight at 50% or smaller throttle openings! This left them 10-20 minutes of time at 75% throttle in which to engage in combat. Use of "Full, or MTO power was restricted to the most desperate situations where the plane would be lost if it did not. Because if you used that throttle setting, you had a better than even chance to land in the Channel with your tanks dry!

I believe that most your misunderstanding stems from the labels used then and now for various throttle settings. I also believe that the rest of your problem comes from the idea that it was possible to fly the plane for more than a few minutes at a time at large throttle openings? ( Over 75%)

#107 Edgar Brooks

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Posted 07 May 2012 - 11:16 PM

I don't have a "problem," either, since the 5 minutes combat setting did not melt the pistons, but had to be noted down, so that, when a certain time (about 1/2 an hour) had been accumulated, the engine needed overhaul.

Edited by Edgar Brooks, 12 May 2012 - 06:19 PM.


#108 NeoConShooter

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Posted 07 May 2012 - 11:44 PM

I'm actually amused that in one topic you are claiming that the Spitfire was rubbish because it didn't do well when fighting across the Channel (a wrong argument, but never mind) and in this topic you are claiming that Sppitfires were deliberatelt hobbled when fighting across the Channel (a wrong argument, but never mind). :D

I never said it was rubbish, or anything even remotely like that above. Please refrain from attributing erroneous statements to me.:mad:
1. I did say that the Spitfire was less effective on the other side of the channel than it was during the BoB.
2. I said that when the Germans were over home/neutral ground and could use equivalent throttle settings, they did better than they did over England.

#109 Ricky

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Posted 08 May 2012 - 07:50 AM

I never said it was rubbish, or anything even remotely like that above. Please refrain from attributing erroneous statements to me.:mad:
1. I did say that the Spitfire was less effective on the other side of the channel than it was during the BoB.
2. I said that when the Germans were over home/neutral ground and could use equivalent throttle settings, they did better than they did over England.


Perhaps I misinterpreted:

7. Other considerations make more of a difference to the performance of planes than the plackard numbers you see in all the books! Those other factors make the Spitfire look great, until you look at it's record over northern France in '44 when those other factors are reversed.



#110 NeoConShooter

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Posted 09 May 2012 - 05:59 AM

can you please link to, quote or offer some plausible formulae to support your assertion. I'm not an expert on aviation, I'm not a pilot, but I do read an unhealthy number of reference books and memoires. I've never come across an account by an Allied or Axis pilot to the effect that they used 15% lower throttle openings when over enemy territory.
I'd be very interested to read who did, where they did it and what their rationale for doing it was.

It is terribly simple. The Germans had to fly from Northern France to a link up with the bombers, then over the channel to England, then to the target and back to base a distance of well over 200, to more than 300 miles. To cover that distance, they had to cover the vast majority of it at 25-35% throttle, cruising at ~200 MPH most of the way. Over England they might run at 50-60% throttle, IF they were close at the start and end and they did not have to go very far inland. All of the above with 10-20 minutes at most at 75% or larger throttle openings after they saw the enemy defenders. It is the back to the base part across the channel that did it. Because their engines were less highly stressed than ours, they could run at 100% for ten minutes compared to our five before things started to melt. ( Or so I was told by my land lord and more than a few other ex-Nazi Pilots!)

You can calculate this out for yourself if you wish. I know that several ,people on this site have listed the fuel consumption figures for various planes, the Spit in particular, take those figures and calculate how much throttle you can use on the reverse of that mission.

Start with landing, with 30 minutes worth of fuel in the tanks at the most economical throttle setting. This is usually about 25 GPH, IIRC, but do not hold me to that figure. ( 13 gallons at landing.)

Then calculate how much gas was burned to get from the middle of the english channel to a point 50 miles inland. To account for various fields and routs. (Say 100 miles at econo cruise, or 13 gallons more.)

Then calc the exfiltration of 50 miles of formation weave at 50% throttle. The so called combat cruise. Call it 20 minutes at 50-60 GPH. ( JUST GUESSING! Use your own correct numbers!) 20 gallons burned. Total now about 46 gallons burned.

then 10 minutes of combat at ~75 gallons per hour, 13 more gallons for 60 total? Again use the right numbers specific to the plane.

Then the 100 miles of ingress at 50% throttle, but with more weight of unburned fuel up, so it does not get as good a mileage figure! Say 25 gallons burned? ( Again use the right numbers. Say 85 gallons total?)

Then the 150 miles to link up and advance to the edge of the combat air space at maybe 30-35 GPH, again because of the extra weight of the unburned fuel to allow for the rest of the trip. Say 20 gallons used? Total 105?

AGAIN FROM MY ADMITTEDLY FAULTY MEMORY!

Do the calcs for real, but adjust the distances flown at small throttle openings to make sure there is gas left for the trip home and reserves. Every pound of extra weight must be offset with more throttle to make up for the increase in induced drag. So if the plane burns 25 GPH at weight X, then it will use 121% more gas at the same speed at weight 110% X, or 30.25 GPH!

My last post for tonight. Hope this helps.

PS if you can't find the right numbers for the Spit or Me-109/Fw-190, MSG the Museum of the USAF in Dayton and ask the research branch for copies of the flight plane charts for the P-51 D. or H. IIRC, they charge .50$ per sheet copied and each plane has two-three dozen. Then do that exercise again to get the true idea of what I say.:D

#111 Flo

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Posted 09 May 2012 - 11:00 AM

You've rather made my point for me?

That's to say that the pilots used different throttle settings according to their tasking.

Your earlier posts about '65% this' or '75% that' are plucked from the air. They were nonsense numbers that make no sense.

As to what throttle setting a particular fighter pilot would use at a particular point in his sweep? Don't guesstimate it, 'ask' them. :D Many accounts given by the fighter pilots we're discussing, or their biographers, deal specifically with combat settings.

Edgar mentioned BoB RAF aircraft using maximum throttle throughout their sortie. Some Luftwaffe fighters did the same over Germany. Likewise, P-38s made long range sweeps over the vast distances of the Pacific at very small throttle settings. None of the three used an arbitrary 10% less when over enemy territory. Generally, when they approached the greatest threat- the Lightnings target, say- they advanced to full throttle.
The defending fighter- also at full throttle- wouldn't be able to take advantage of the part throttle approach of his foe, that part of the flight profile would be over before they met.

Your oft repeated assertion that "most pilots didn't see who shot them down" isn't quite the same as 'being unaware of the possibility of attack'.
Quite the reverse, most aircraft shot down in WW2 combat were lost in fully developed combat- dogfights.
Being shot down from ambush- 'bounced'- was rare enough to warrant specific comment in most wartime pilots autobiographies.

I appreciate your memory may not be what it once was, Stewart. That's fine, really. :) Just do a wee check that what you're about to post is correct.
You're in front of a computer. Just google the subject. Eg, Wikipedia isn't quite as knowledgeable as specialist reference books or expert opinion, but it's a great tool for checking that the broad thrust of your argument is correct.

:) I'm not trying to lecture you mate, just offer a wee bit of friendly advice? Sorry if it sounds a bit patronising.

Edited by Flo, 09 May 2012 - 11:03 AM.
pompous a*se disclaimer!


#112 Kutscha

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Posted 09 May 2012 - 02:11 PM

At 5000m at max continuous (2400rpm, 323mph) the Bf109E-3 had an endurance of 55min and a of range of 286mi.

At 5000m at max economy (1400rpm, 217mph) the Bf109E-3 had an endurance of 1.5hr and a of range of 413mi.

Almost all Lw s/e fighters were based in the Pas de Calais area.
Abbeville to London is 130mi.
Wissant to London is 90mi.
St Omer to London 115mi.

The DB601A had a time limit of 5 min at max power (1.3ata) except on take off when it was 1 min (1.4ata).

Sorry Flo but full throttle was not used unless to engage in combat. It was just too hard on the engines. Max continuous throttle would be the norm.

I agree this % throttle is nonsense. Using the DB601 for example:

30% of 2400 = 720rpm
30% 0f 1.4ata = 0.42ata

#113 Ricky

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Posted 09 May 2012 - 02:15 PM

Bottom line - Escorts cruise to their target while Interceptors race to theirs, but once battle is joined everybody goes as fast as possible.

#114 Flo

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Posted 09 May 2012 - 02:50 PM

Isn't that what I said? :D
Ricky put it better, but to clarify: one setting to get there, another for combat, neither arbitrarily chosen because the fighter was in any particular location. Especially no '-10%' rule for operating over enemy territory.

#115 GregP

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Posted 09 May 2012 - 03:28 PM

Neo,

We own Merlins and Allisons and I build Allisons for a living. At cruise a Merlin burns a US gallon a minute or 60 gallons per hour. You might get it down to 50if you push it, but most owners don't. You can get an Allison down to about 45 gallons per hour, but it is happier at 48 - 55.

At 25 gallons per hour, you will have burned up either engine or caused it to stop from being too lean unless you are at idle power on the ground without a propeller installed.

Where do you get your numbers? They are clearly not from the world of operating engines and aircraft.

#116 Kutscha

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Posted 09 May 2012 - 05:22 PM

Posted Image

Posted Image

Edited by Kutscha, 09 May 2012 - 05:26 PM.


#117 NeoConShooter

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Posted 10 May 2012 - 01:23 AM

[quote name='Edgar Brooks'][quote name='NeoConShooter']
My understanding (drop the "mis" please) is that the maximum setting was 3,000 rpm, which was only to be used at take-off, to 1000' (not 5 minutes,) then 2,850 rpm maximum climb (maximum 1 hour,) then continuous rich or lean, at 2,650 rpm, with a 5 minutes limit at 3000 rpm for combat, though 30 minutes, at that setting, was permitted above 20,000'.
I don't have a "problem," either, since the 5 minutes combat setting did not melt the pistons, but had to be noted down, so that, when a certain time (about 1/2 an hour) had been accumulated, the engine needed overhaul.[/QUOTE]
The RPM figures by them selves are absolutely meaningless. What was the throttle poss, manifold pressure, prop setting, mixture setting, altitude, speed, loaded condition of the plane, as in heavy or lite, etc. What other conditions?
The five minutes at combat power remark was made in response to the video someone posted of the game pilot who flew an intercept with the engine set at full throttle, MTO in modern parlance, with the mixture at the LEAN setting! I'll bet that if we ask the engine builder guy for his opinion, who's name I am so sorry because I can't at this moment remember it, whether or not that plane's engine would last that long or melt the pistons at LEAN mixture?

#118 Wuzak

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Posted 10 May 2012 - 01:44 AM

The RPM figures by them selves are absolutely meaningless. What was the throttle poss, manifold pressure, prop setting, mixture setting, altitude, speed, loaded condition of the plane, as in heavy or lite, etc. What other conditions?
The five minutes at combat power remark was made in response to the video someone posted of the game pilot who flew an intercept with the engine set at full throttle, MTO in modern parlance, with the mixture at the LEAN setting! I'll bet that if we ask the engine builder guy for his opinion, who's name I am so sorry because I can't at this moment remember it, whether or not that plane's engine would last that long or melt the pistons at LEAN mixture?


The throttle position is meaningless. The RPM and boost settings are more important. The throttle position will change with altitude to maintain boost pressure settings.

Can't have METO with lean mixture. There will be a maximm boost the engine can run in lean, which won't be nearly as much as for METO.

#119 GregP

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Posted 10 May 2012 - 01:47 AM

Hi Kutscha,

Thanks for the posted tables. Nobody today cruises above 12,000 feet or so ... maybe as high as 15,000 feet. If you have a fighter, who wants to waste the engine life in straight and level IFR flight?

We have more than 100 Allisons out in the flying world and know more than 80 Merlin users, and NOBODY gets 25 gallons per hour at 10,000 feet and below. If you do that (might be possible to sustain operation), you'll wind up paying Mike Nixon or somebody else to overhaul the Merlin and Joe Yancey or somebody else to overhaul the Allison WAY TOO SOON.

But, by all means, go ahead if you want to prove it is possible. You coudl be right ... and doing that is very good for Joe's business.

The tables you posted are for Merlins owned by a government, with government-paid mechanics and massive spare parts inventories. There aren't any government-owned Merlins flying in the world except maybe the British BOB Memorial Flight, and they don't want to overhaul their Merlins anymore than any other owner does these days, and they don't have more parts than anyone else does.

If you don't run the V-12's at a decent power level, you'll PAY in the end, and much sooner than you expect to.

Allisons aren't happy producing less than 550 - 600 HP in flight. Idling on the ground is OK until you heat up, but they are made to fly with airflow though the radiator and with the oil in the green temperature range. Most people cruise them at 2,000 rpm and 30 inches of MP, and 3,000 rpm and 50 to 70 inches at airshows ... and they get GREAT engine life.

We have one customer who runs his Allisons at 4,000+ rpm and 160 inches of MP, and he has been doing that for more than 10 years in a tractor with no failures. Of course, a tractor pull is a short engine run! He runs three Allisons putting out over 3,000 HP each!

Edited by GregP, 10 May 2012 - 01:54 AM.


#120 Kutscha

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Posted 10 May 2012 - 02:10 AM

Greg, you are starting to sound like Crumpp. He confuses today with yesterday all the time.

The thread is not about today but yesterday. What is relevant is how they were operated yesterday, not how they are operated today.




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