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  • ED Team
Posted
Moderators Please Prevent this from turning into another Debate about Stability of the Spitfire...........

 

Thank You.......

 

On a side not that i think the main point of thead is about i cant wait for the Spitfire:P

 

I'd have to agree... I'm not sure what you guys are fighting about anymore, I would assume whatever it is, it could be taken to PMs...

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Posted

Where it all begun... a great watch

 

City Hall is easier to fight, than a boys' club - an observation :P

"Resort is had to ridicule only when reason is against us." - Jefferson

"Give a group of potheads a bunch of weed and nothing to smoke out of, and they'll quickly turn into engineers... its simply amazing."

EVGA X99 FTW, EVGA GTX980Ti FTW, i7 5930K, 16Gb Corsair Dominator 2666Hz, Windows 7 Ultimate 64Bit, Intel 520 SSD x 2, Samsung PX2370 monitor and all the other toys

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"I am a leaf on the wind, watch how I soar"

Posted
Ok, then the instability was never fixed. There were no design changes to move the AC and the stability Margin of the Mk IX remained the same as the Mk V.

 

The instability never existed, Mk IX Spits have a bigger engine/nose not tailplane, if you like I can provide a diagram so you know which end of the aircraft we are talking about.

 

Just because you do not understand the issue does not mean it does not exist Fredrick.

 

Just because an issue does not exist does not mean we don't understand it.

 

Anyway, feel free to produce the evidence of the claim.

Posted
Where it all begun... a great watch

 

 

awesome Wolf Rider..........:thumbup:

P-51, 190-D9, 109-K4, Spitfire MK IX, Normandy, and everything else:joystick:

i7 4770K, 4.3ghz, 32gb ram, Windows-10 Pro, Z87 Exstreme4, Corsair 850w psu, Samsung Evo 1T SSD & 250 SSD, Titan-X 12gb OC, Asus ROG Swift 27"/1440p/144hz/1ms monitor, Trackir 5, TM Warthog & 10cm extension, Saitek TPM, MFG crosswind pedals

Posted

Spitfire no longer shows up in the ME for me with the latest 1.5 patch. Anyone else?

P-51D | Fw 190D-9 | Bf 109K-4 | Spitfire Mk IX | P-47D | WW2 assets pack | F-86 | Mig-15 | Mig-21 | Mirage 2000C | A-10C II | F-5E | F-16 | F/A-18 | Ka-50 | Combined Arms | FC3 | Nevada | Normandy | Straight of Hormuz | Syria

Posted
Spitfire no longer shows up in the ME for me with the latest 1.5 patch. Anyone else?

 

Yeah I got a bit of a shock when flying the FW-190 and all of a sudden got jumped by a gaggle of A-10s that DCS had automatically replaced the spits with.

PC:

 

6600K @ 4.5 GHz, 12GB RAM, GTX 970, 32" 2K monitor.

 

  • 2 weeks later...
Posted

Came across this in a post in a thread on another board,

 

RAF Merlin 66 Spitfire cooling tests showed that it would take approx. 46 minutes at +25 lbs boost for the the Merlin 66's coolant temperature to rise from the 89 deg. C cruise temperature, to the 135 deg C maximum.

 

Would be interesting to see this report.

Posted

That would be a very curious test report indeed, considering that the Merlin 66 had an hourly consumption rate of 197 imp. gallon / hour at +25 lbs/sq. inch boost and that the IXLF had a 85 gallon fuel tank...

 

... meaning that the thing would run its tanks dry at +25 lbs boost in a little under 26 minutes.

 

So, one has to wonder about how in this allegedly existing test they managed to run the engine at +25 lbs for another 20 minutes after the fuel run out. ;)

http://www.kurfurst.org - The Messerschmitt Bf 109 Performance Resource Site

 

Vezérünk a bátorság, Kísérőnk a szerencse!

-Motto of the RHAF 101st 'Puma' Home Air Defense Fighter Regiment

The Answer to the Ultimate Question of the K-4, the Universe, and Everything: Powerloading 550 HP / ton, 1593 having been made up to 31th March 1945, 314 K-4s were being operated in frontline service on 31 January 1945.

Posted
That would be a very curious test report indeed, considering that the Merlin 66 had an hourly consumption rate of 197 imp. gallon / hour at +25 lbs/sq. inch boost and that the IXLF had a 85 gallon fuel tank...

 

... meaning that the thing would run its tanks dry at +25 lbs boost in a little under 26 minutes.

 

So, one has to wonder about how in this allegedly existing test they managed to run the engine at +25 lbs for another 20 minutes after the fuel run out. ;)

 

Drop Tanks?

Posted (edited)
Drop Tanks?

 

That, or ground test stand and/or wind tunnel. I know that similar tests were run for the US Packard Merlins before standardizing the uprated WEP limits (72/75 and 90"), where it had to be run for seven(!!!) hours straight at the WEP rating without failing. It was accomplished on a test stand with a simulated cooling system; I would imagine a wind-tunnel type setup blowing through the radiator assembly

Edited by OutOnTheOP
Posted
That, or ground test stand and/or wind tunnel. I know that similar tests were run for the US Packard Merlins before standardizing the uprated WEP limits (72/75 and 90"), where it had to be run for seven(!!!) hours straight at the WEP rating without failing. It was accomplished on a test stand with a simulated cooling system; I would imagine a wind-tunnel type setup blowing through the radiator assembly

 

The truth is actually its much profane - there is simply no a test in which they run the thing at 46 minutes at +25 lbs, period.

 

The 46 minute running a +25 is just a brainchild of a single spitfire fan guy, his own loosly based 'calculations' after the results of the cooling trials of JL 165. In the actual test which they climbed that plane with a rather cold engine for about 2-2.5 minutes with +25 lbs boost, on rather cold morning (6 Celsius or so).

 

That is how internet myths are born, I am afraid.

http://www.kurfurst.org - The Messerschmitt Bf 109 Performance Resource Site

 

Vezérünk a bátorság, Kísérőnk a szerencse!

-Motto of the RHAF 101st 'Puma' Home Air Defense Fighter Regiment

The Answer to the Ultimate Question of the K-4, the Universe, and Everything: Powerloading 550 HP / ton, 1593 having been made up to 31th March 1945, 314 K-4s were being operated in frontline service on 31 January 1945.

  • 2 weeks later...
Posted
You think that Mk IX will make you an absolute winner?

I have bad news for those who consider P-51 too stick sensitive and thus prone to stall... :)

As Spitfire has neutral stability there is only 3/4" of stick travel to stall as it was reported by NACA. Really silk hands or full scale joystick required... :)

It will be no mercy, hardcore only - all will be as Mitchell designed.

 

The user-programmable stick curve is your friend!:smilewink:

Kit:

B550 Aorus Elite AX V2, Ryzen 7 5800X w/ Thermalright Phantom Spirit 120 SE, 2 x 16GB Kingston Fury DDR4 @3600MHz C16, Asus ROG Strix RTX 4070 Ti Super 16GB, EVGA SuperNova 750 G2 PSU, HP Omen 32" 2560x1440, Thrustmaster Cougar HOTAS fitted with Leo Bodnar's BU0836A controller.

--Aviation is the art of throwing yourself at the ground, and having all the rules and regulations get in the way!

If man was meant to fly, he would have been born with a lot more money!

Posted
That, or ground test stand and/or wind tunnel. I know that similar tests were run for the US Packard Merlins before standardizing the uprated WEP limits (72/75 and 90"), where it had to be run for seven(!!!) hours straight at the WEP rating without failing. It was accomplished on a test stand with a simulated cooling system; I would imagine a wind-tunnel type setup blowing through the radiator assembly

 

I've heard of similar hours-at-WEP ground tests on Allisons. The way I heard it, the engine was "unloaded;" the propeller wasn't attached, meaning that the engine wasn't working as hard, and so didn't have as bad of heating problems, and thus could run for much longer than it could in the actual aircraft. Or something like that.

Posted
've heard of similar hours-at-WEP ground tests on Allisons. The way I heard it, the engine was "unloaded;" the propeller wasn't attached, meaning that the engine wasn't working as hard, and so didn't have as bad of heating problems, and thus could run for much longer than it could in the actual aircraft. Or something like that.

 

You ae correct Echo38!

 

It was industry standard and aviation convention to endurance test engines. Overboosting them made it even more critical due to the extreme stress on the engine.

 

In all the development and testing engines, the Merlin 66 program ran 1000 hours of test stand time before they got a single engine to last 100 hours. The Rolls Royce engineers were very concerned even with that testing that it did not subject the engine to enough stress to reproduce an operational environment.

 

That 100 hours on a test stand represents the minimum criteria for a service clearance. If you want to know how long you can run the engine at an overboosted condition without risking immediate engine failure...read the Operating Instructions! In this case, 100 hours on a test stand got you 5 minutes in an operational environment and some pretty serious cautions if you used it. It had to be reported, recorded, and the engine inspected with each use.

 

Looking at any of the endurance testing and getting excited about how "strong" their engine is (BMW, Rolls Royce, Daimler Benz, Allison, etc..) is simply obtuse.

 

Usually it is on a test stand with a device called a "club" instead of propeller.

 

A club is basically a shortened propeller that provides necessary engine cooling.

 

http://www.motoart.com/products/miscellaneous/radial-test-club-wall-art

 

It can also have a torque stand which usually has a dynamomoter which applies torque to the shaft.

 

No matter which method, there is a conversion depending on which method to correct the test stand data to flight conditions.

 

Yes, actual flight is much harder on the engine.

Answers to most important questions ATC can ask that every pilot should memorize:

 

1. No, I do not have a pen. 2. Indicating 250

Posted
I've heard of similar hours-at-WEP ground tests on Allisons. The way I heard it, the engine was "unloaded;" the propeller wasn't attached, meaning that the engine wasn't working as hard, and so didn't have as bad of heating problems, and thus could run for much longer than it could in the actual aircraft. Or something like that.

 

Cant run WEP settings without a load... You'll overrev the thing before you are anywhere near full throttle. As Crumpp states a club prop or brake would have to be fitted able to absorb the power produced.

 

But yes static runs werent able to replicate real world stresses back then!

Posted
But yes static runs werent able to replicate real world stresses back then!

 

For running the engine in a static environment but flight conditions are not static.

Answers to most important questions ATC can ask that every pilot should memorize:

 

1. No, I do not have a pen. 2. Indicating 250

Posted

2yuf66f.jpg

 

27zknxd.jpg

 

akv13p.jpg

 

2v1t7hf.jpg

Answers to most important questions ATC can ask that every pilot should memorize:

 

1. No, I do not have a pen. 2. Indicating 250

Posted
2yuf66f.jpg

 

27zknxd.jpg

 

akv13p.jpg

 

2v1t7hf.jpg

 

This would appear to offer some leeway to the aircraft captain. For example:

 

 

a. “Engine limitations which the pilot should observe”. I suggest that the use of the work should, appears to indicate some discretionary freedom to do otherwise.

 

 

b. “Flying restrictions. Rear fuselage tanks may be used only with special authority and never on aircraft with “rear view” fuselages.” Use of the word never, clearly leaves no room for leeway. It is interesting to note that the word never is not used in relation to the engine limitations; reasonably so I would suggest.

 

 

c. “To give the engine a reasonable life between overhauls”. If an aircraft is in serious danger of being destroyed in combat, the engine may not be given the chance of living long enough to receive the next overhaul. I suggest that under such circumstances, also considering the risk to human life, the aircraft captain could reasonably be expected to decide, at his discretion, to risk operationally overloading the engine, beyond the 5 minutes at 3,000 rpm combat limit for example.

 

 

d. I suggest that these engine limitations are somewhat ambiguous (Open to more than one interpretation; not having one obvious meaning; not clear or decided). Moreover, I suggest this is reasonably and deliberately so. I don't believe that limits could be definitely calculated or proved in relation to exact failure points and, with RR engines, it would appear to be entirely sensible to give the aircraft captain an appropriate level of discretionary freedom in operational combat. For example, it is not clear whether the 5 minute at 3,000 rpm combat limit is once per flight, once every 10 minutes or once every hour, etc.

I have seen a record of RAF Boscombe Down using a Spitfire engine (not one discussed above) combat rating normally permitted for periods of five minutes only, but with a concession for test purposes, being allowed full climbs to be made at this rating. Of course, testing and operational flying are very different, but still involve risk. The pilot notes engine limitations are part of risk management, but I don't think that to use the combat rating for more than 5 minutes should mean that engines should immediately break down in DCS. However, if DCS starts to simulate and model engine wear and tear and overhaul periods, then we will be in different territory.

Finally, if an aircraft engine was so vulnerable to immediate breakdown if used beyond a stated combat limit time, I suggest that the operation to disengage the combat setting would be automated and not left to the pilot. I think some engines had such WEP limiting timed cut-off systems, but not RR engines; I stand to be corrected if I have got that wrong. RR tests that I have read about, using combat settings for extended periods have appeared to eventually achieve great success with extended use.

 

Happy landings,

 

Talisman

Bell_UH-1 side.png

Posted

 

2v1t7hf.jpg

 

For some reason "secure an adequate margin" was not highlighted in (iii).:sly:

There are no reference sources given from where the documentation posted came from either.

Posted

 

d. I suggest that these engine limitations are somewhat ambiguous

 

5 minutes seems pretty clear. If you want to take your airplane beyond the limitations, feel free to do it.

Answers to most important questions ATC can ask that every pilot should memorize:

 

1. No, I do not have a pen. 2. Indicating 250

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