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The Staff of SOH
Seafire III - did it have WEP?
- Thread starter UncleTgt
- Start date
bearcat241
SOH-CM-2023
The Mk III used the Merlin 32, which had no WEP boost. It seems that RR products of the WWII years relied entirely on the optimal boost pressure derived from their existing two speed supercharger technology. After RR finally got the coolant, supercharger and carbueration bugs ironed out, and finally installed fuel injection into their products (all with a little help from the Yanks i might add), it wasn't until well into postwar times that they managed supercharger upgrades that equaled the output of true injected WEP of those times. Seems that their biggest problems (besides the ubiquitous fuel octane issues throughout the UK) was mainly in design flaws that plagued the line with parts failures. Incidentally, had they used it under these conditions, WEP might have proven even more disastrous under the dramatic boost pressures generated by injected war emergency power methods of that period.
Now the licensed, US built Packard-Merlin V-1650 was an entire different story, as we've witnessed in the success of the P-51 Mustang variants which were powered by it. It kept the basic design of the Merlin line, but added American technologies which enhanced its performance in supercharger boost, plus the integration of both fuel injection and WEP. As a result, it gave the P-51 outstanding fuel economy and performance throughout the range of altitude over the early Allison engine. It may be this same success story that probably leads most folks to thinking that all Merlin products were WEP equipped. In the end, the Packard-Merlin was a great collaboration story.
Now the licensed, US built Packard-Merlin V-1650 was an entire different story, as we've witnessed in the success of the P-51 Mustang variants which were powered by it. It kept the basic design of the Merlin line, but added American technologies which enhanced its performance in supercharger boost, plus the integration of both fuel injection and WEP. As a result, it gave the P-51 outstanding fuel economy and performance throughout the range of altitude over the early Allison engine. It may be this same success story that probably leads most folks to thinking that all Merlin products were WEP equipped. In the end, the Packard-Merlin was a great collaboration story.
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What is WEP?
I believe the answer depends a bit on what you consider to be WEP.
At least in CFS1, there are three kinds of WEP:
1. Water Injection (5 minute limit)
2. Water Methanol Injection (10 minute limit)
3. Supercharger Boost Increase (5 minute limit)
The stock P-51 uses additional Supercharger boost and if you run WEP longer than 5 minutes (about 10-15 seconds longer), you engine suffers crippling damage. In reality, your engine probably would not destroy itself as in the game, but you might be needing new spark plugs or an overhaul much sooner than expected.
The distinction between Packard Merlins and Rolls Royce Merlins isn't particularly noticeable from a performance standpoint. The nominal output is pretty much the same between the V-1650 in the Mustangs and the Merlin 60 series that it was copied from in the Spitfires. In fact, Spitfires used both kinds of engines: The Spitfire Mk.IX used a RR Merlin and the Spitfire Mk.XVI used a Packard Merlin. Other than that, they were identical aircraft with pretty much identical performance.
That does not mean the engines were parts interchangeable. The manufacturing methods were different and some parts such as intake manifolds were manufactured in different pieces, but that difference could be seen in different Marks of Merlins even by Rolls Royce.
Regarding the performance of Merlin Mustangs being superior to Allison Mustangs: The USAAF claim was that at 10,000 feet and below, the P-51A with the Allison was the fastest of all the wartime aircraft. (410 mph @ 12,000 feet)
Regards.
- Ivan.
I believe the answer depends a bit on what you consider to be WEP.
At least in CFS1, there are three kinds of WEP:
1. Water Injection (5 minute limit)
2. Water Methanol Injection (10 minute limit)
3. Supercharger Boost Increase (5 minute limit)
The stock P-51 uses additional Supercharger boost and if you run WEP longer than 5 minutes (about 10-15 seconds longer), you engine suffers crippling damage. In reality, your engine probably would not destroy itself as in the game, but you might be needing new spark plugs or an overhaul much sooner than expected.
The distinction between Packard Merlins and Rolls Royce Merlins isn't particularly noticeable from a performance standpoint. The nominal output is pretty much the same between the V-1650 in the Mustangs and the Merlin 60 series that it was copied from in the Spitfires. In fact, Spitfires used both kinds of engines: The Spitfire Mk.IX used a RR Merlin and the Spitfire Mk.XVI used a Packard Merlin. Other than that, they were identical aircraft with pretty much identical performance.
That does not mean the engines were parts interchangeable. The manufacturing methods were different and some parts such as intake manifolds were manufactured in different pieces, but that difference could be seen in different Marks of Merlins even by Rolls Royce.
Regarding the performance of Merlin Mustangs being superior to Allison Mustangs: The USAAF claim was that at 10,000 feet and below, the P-51A with the Allison was the fastest of all the wartime aircraft. (410 mph @ 12,000 feet)
Regards.
- Ivan.
bearcat241
SOH-CM-2023
Same with CFS2, except the sim doesn't recognize supercharger boost alone when applying a WEP gauge or key command. The air file 505 section must show one of the first two you listed above in order for a gauge or key command to activate WEP. So, when modding the air file of a Spit or Seafire you have to add conventional WEP options 1 or 2 above to get supercharger simulation. I think this is the question UncleTgt might be driving at in this thread. BTW, turbocharger boost (ala the P-47) is the fourth category, again, not recognized by the sim.
Never knew that...thanks
Below is a good example of a supercharger WEP gauge, from a Rebuffat Spit VII package IIRC.
Attachments
UncleTgt
SOH-CM-2025
Interesting snippets guys, thank you.
I was prompted by DD73's comments about needing to replace the AH Seafire LIII with the Seafire 15 for his Operation Meridian CAP missions, because he thought the AH Seafire lacked "oompf". Maybe an air file with a non-linear throttle profile (record 506) would adequately mimic the application of supercharger "boost" in combat? The AH Seafire record 506 is a simple straight line.
I was prompted by DD73's comments about needing to replace the AH Seafire LIII with the Seafire 15 for his Operation Meridian CAP missions, because he thought the AH Seafire lacked "oompf". Maybe an air file with a non-linear throttle profile (record 506) would adequately mimic the application of supercharger "boost" in combat? The AH Seafire record 506 is a simple straight line.
kelticheart
Charter Member
Hi Ivan,
let me confirm your comments. Mustangs are my favourite planes and I read everything I could about their history.
I am very lucky to own a book written by Norm Avery (if my memory is serving me right about his name), one of North American Aviation primary engineers in the 1940's, who worked in all of NAA major projects, starting from the T-6 Texan all the way up to the F-86 Sabre.
I used this book many times since I bought CFS2, and I used it to fine tune several Mustang real life flight models, I combined into one, for CFS2 Merlin-engined P-51 Mustangs uploaded here and there.
Mr. Avery was very involved with the P-51 program and devoted several pages of the Mustang project development story in the chapter dedicated to the P-51. Tests to replace the Allison with a Merlin 60 series were run independently by both Rolls Royce and NAA. The test aircraft which produced a literal earthquake in USAAF top brass, when they were told the results, was a P-51 modified by NAA, equipped with an original Merlin shipped over from England. Mass produced Packard-built Merlins came a little later on, Packard was still getting up to speed for a full blown wartime production rate, at the time. The book even reports the serial number of this aircraft, but I cannot remember it, and the top speed reached by this very first P-51B was 440 mph @ 25,000'. I am sorry, but I am not 100% sure about the altitude, yet positive about the top speed figure, I'll have to check.
NAA had already introduced on this test aircraft the modifications which created the legendary Merlin-engined Mustang unmistakable shape, with the carb intake under the propeller and the positive-push belly radiator. Later modifications to the radiator intake duct, a Venturi tube, reached mass production status from the very beginning.
I am at work now, but I can reply reporting even the date when the flight test was carried out. Definitely, Allison-powered P-51s were not the best wartime aircrafts overall, but they were the fastest at low altitudes, where the Allison gave its best output. Coupled with the lowest drag airframe ever built before and laminar flow wings, Allison powered P-51As and Mustang MkIs provided fiery performance. They were vicious attackers and formidable opponents in dogfights, but at low altitudes.
Improving an aircraft, already with an extreme potential promise, performance at high altitude, thus capable to provide escort for the exhausted 8th USAAF bombers attacking Germany, is what generated the idea to re-engine it with something already combat-proven like the Spitfire engine. In 1943 the American industry was already contributing heavily to the British war effort and RR Merlin engines for Hurricanes, Lancasters and Mosquitoes were already being produced in the U.S.
One last note from Mr. Avery's book is that the best performing Mustang version was the "razorback" model, either the Inglewood, CA built "B" or the identical, Dallas, TX built "C" version. Coupled with powered ammo belt feeders to prevent gun jamming and British-built Malcom hoods, the razorback Mustangs were judged by pilots, who later flew the bubbletop "D" version, the best o' the best, true hotrods of the sky.
The more famous bubbletop "D" versions had strengthened wings and an extra couple of .50" guns, plus ammo, which made them heavier. This consequently reduced their top speed to about 420-425 mph and rendered them slightly less manoeuvrable in combat.
Cheers!
KH
Hello Kelticheart, Bearcat241,
Thanks for a little additional history lesson.
Just a minor note though: The P-51A was actually the Mustang Mk.II and had a better engine than the Mk.I. The problem was that it was only in production for a few months because the Merlin version took over after. There were only about 300 aircraft built and most of them served with the British. There were also a few that made it to the CBI theatre but not many. The fuel consumption on the Allisons was actually lower but range was less because they didn't have the fuselage fuel tank. The engine was also much more durable than the Merlin and a few served until the end of the war which is amazing in my opinion.
One of the reasons for the revised wing structure from the razorback to bubble top Mustangs is because at VERY high speeds, the top of the wings on the early version would deform and could cause a wing failure. Such an event killed Tommy Hitchcock while testing the Mustang in a high speed dive.
Just as another note, I don't actually fly CFS2 hardly at all. I do most of my flying and such on CFS1 but just saw this as an interesting topic in the new posts area.
Back to the original topic of Spitfires and WEP:
The actual engine output will be very dependent on the manifold pressure limits. Below critical altitude, there is more boost than the engine can safely handle. Now the big question is what time period we are discussing for a particular version of Spitfire because the quality of fuel (octane) was steadily improved as the war progressed. As the fuel octane increased, the allowable manifold pressure increased which is why you get things like a 2000 hp Spitfire Mk.IX at the end of rthe war.
As for what WEP is in the simulators, I am really not all that sure. If there is a requirement for anti-detonant such as MW50 or Water injection, the limit should be whatever the supply is, but what if the anti-detonant is just plain fuel such as the German C3 Injection (Einspritzung) as on the FW 190? You don't really run out of that so limits are really policy limits.
Life gets even more interesting when you start looking at how different air forces and manufacturers handled power settings.
Most folks had a "Combat" rating which was limited to about 5 minutes.
They also may have had a "Climb" rating which was limited to around 30 minutes.
Besides that there was most likely a "Maximum Continuous" and an "Economy" setting.
The Japanese however typically have a "Take-Off" rating which is only 1 minute in duration.
What should we do when US forces note that with certain aircraft (Specifically the Ki-43 Hayabusa) that aircraft is capable of excellent "Flash performance" and that their pilots routinely exceed specified throttle settings with apparently no consequence?
Sorry if I pulled this discussion way off topic.
- Ivan.
Thanks for a little additional history lesson.
Just a minor note though: The P-51A was actually the Mustang Mk.II and had a better engine than the Mk.I. The problem was that it was only in production for a few months because the Merlin version took over after. There were only about 300 aircraft built and most of them served with the British. There were also a few that made it to the CBI theatre but not many. The fuel consumption on the Allisons was actually lower but range was less because they didn't have the fuselage fuel tank. The engine was also much more durable than the Merlin and a few served until the end of the war which is amazing in my opinion.
One of the reasons for the revised wing structure from the razorback to bubble top Mustangs is because at VERY high speeds, the top of the wings on the early version would deform and could cause a wing failure. Such an event killed Tommy Hitchcock while testing the Mustang in a high speed dive.
Just as another note, I don't actually fly CFS2 hardly at all. I do most of my flying and such on CFS1 but just saw this as an interesting topic in the new posts area.
Back to the original topic of Spitfires and WEP:
The actual engine output will be very dependent on the manifold pressure limits. Below critical altitude, there is more boost than the engine can safely handle. Now the big question is what time period we are discussing for a particular version of Spitfire because the quality of fuel (octane) was steadily improved as the war progressed. As the fuel octane increased, the allowable manifold pressure increased which is why you get things like a 2000 hp Spitfire Mk.IX at the end of rthe war.
As for what WEP is in the simulators, I am really not all that sure. If there is a requirement for anti-detonant such as MW50 or Water injection, the limit should be whatever the supply is, but what if the anti-detonant is just plain fuel such as the German C3 Injection (Einspritzung) as on the FW 190? You don't really run out of that so limits are really policy limits.
Life gets even more interesting when you start looking at how different air forces and manufacturers handled power settings.
Most folks had a "Combat" rating which was limited to about 5 minutes.
They also may have had a "Climb" rating which was limited to around 30 minutes.
Besides that there was most likely a "Maximum Continuous" and an "Economy" setting.
The Japanese however typically have a "Take-Off" rating which is only 1 minute in duration.
What should we do when US forces note that with certain aircraft (Specifically the Ki-43 Hayabusa) that aircraft is capable of excellent "Flash performance" and that their pilots routinely exceed specified throttle settings with apparently no consequence?
Sorry if I pulled this discussion way off topic.
- Ivan.
Blood_Hawk23
Charter Member
Awesome info...
The Seafire MKIII was based on which version of the Spitfire. I could look it up in my books but I don't want to
So which form of boost, if any would it have.
I do know if you add the boost to the engine that there is a performance gain even without the WEP. I've done it to some of the WWI cfg files to give the player an advantage while climbing.
Little reminder / side note.
Make the same Adjustments to the .Air file that you make to the .CFG, unless you want the AI to have different engine power.
The Seafire MKIII was based on which version of the Spitfire. I could look it up in my books but I don't want to
So which form of boost, if any would it have.
I do know if you add the boost to the engine that there is a performance gain even without the WEP. I've done it to some of the WWI cfg files to give the player an advantage while climbing.
Little reminder / side note.
Make the same Adjustments to the .Air file that you make to the .CFG, unless you want the AI to have different engine power.
Blood_Hawk23
Charter Member
Ok. you made me look.
MKIIIs had the Merlin 55M of 1585hp. I can't find any reference to the Spits using that engine. Thats just in the book I have. I haven't looked else where yet.
Here is what I found on good old wiki, right or wrong I don't know.
http://en.wikipedia.org/wiki/List_of_Rolls-Royce_Merlin_variants
Here is a bit more. Wiki as well, Sorry...
http://en.wikipedia.org/wiki/Rolls-Royce_Merlin
MKIIIs had the Merlin 55M of 1585hp. I can't find any reference to the Spits using that engine. Thats just in the book I have. I haven't looked else where yet.
Here is what I found on good old wiki, right or wrong I don't know.
| Merlin 55 | 1,185 hp (884 kW) at 3,000 rpm | 1,470 hp (1,096 kW) at 3,000 rpm, +16 psi (110 kPa), 9,250 ft (2,819 m) | Spitfire Mk.V and Seafire Mk.III | |
| Merlin 55M | 1,230 hp (917 kW) at 3,000 rpm | 1,585 hp (1,182 kW) at 3,000 rpm, +18 psi (124 kPa) boost, 2,750 ft (838 m) | Spitfire LF Mk.V, Seafire Mk.III | Variant with "cropped" supercharger impellor |
http://en.wikipedia.org/wiki/List_of_Rolls-Royce_Merlin_variants
Here is a bit more. Wiki as well, Sorry...
- Merlin 50.M (RM 5S)
http://en.wikipedia.org/wiki/Rolls-Royce_Merlin
Blood_Hawk23
Charter Member
After reading through both of my books and through all the wiki had to offer, I see no mention of War Emergency Power. At least for the 55 series. I'm not sure if that +18 psi was the max boost or if it could go higher.
misson
Charter Member
My 2 cents!
I´ve made conversion of AF Scrub Seafire MK3 simply runing Airwrench but really dont know if it used WEP or not.
Some planes like germans used water ingection (see what happen if u drop some particles of water on the fire) and other planes methanol , but times out of these weps seems to be due to avoid engine overheatings.
Cheers
Mario
I´ve made conversion of AF Scrub Seafire MK3 simply runing Airwrench but really dont know if it used WEP or not.
Some planes like germans used water ingection (see what happen if u drop some particles of water on the fire) and other planes methanol , but times out of these weps seems to be due to avoid engine overheatings.
Cheers
Mario
kelticheart
Charter Member
BH,
I'll take a peek into my copy of "Jane's Combat Aircrafts of WWII" book and let you know. It has an end section all dedicated to the most diffused aviation engines during WWII, sorted by country.
Cheers!
KH
If you look strictly for War Emergency Power, you probably won't find that exact wording, but as I mentioned earlier, different organizations used different terminology for pretty much the same basic things:
Look for a "Combat" rating and how long it may be used for. If it is a 5 minute rating then it is the equivalent of what we normally consider to be WEP. If you are looking for a anti-detonant or oxidizer, I am pretty sure that none of the wartime Merlins used anything like that. If this does not qualify as WEP in your opinion, then many other aircraft such as the Mustangs don't have such a rating either.
- Ivan.
Look for a "Combat" rating and how long it may be used for. If it is a 5 minute rating then it is the equivalent of what we normally consider to be WEP. If you are looking for a anti-detonant or oxidizer, I am pretty sure that none of the wartime Merlins used anything like that. If this does not qualify as WEP in your opinion, then many other aircraft such as the Mustangs don't have such a rating either.
- Ivan.
Blood_Hawk23
Charter Member
Here is a question. Was NOS, Nitrous Oxide, Ever used on piston aircraft?
bearcat241
SOH-CM-2023
Blood_Hawk23
Charter Member
That is funny.
But you know some of those people have their facts mixed up. They are trying to relate a car to a plane and miss the whole point.
The engine would have to be almost at max power, but not at max power, before the NOS could be used. It would give the engine an instant jump in RPMs and HP as long as it was active. I'd say no more than 30 seconds to a minute.
Which would explain why the Germans would want to use it on interceptors. All they would need would be harden cylinder walls and forged pistons.
I think the biggest problem the Germans would have faced would have been their engineering tolerances. The spec would be too tight. Now do the same mod on a Russian engine and look out. That is if the engine didn't blow up first.
I did some digging at www.avialogs.com (you .air file builder may want to bookmark it as it loaded with pilot manuals and other good tid bits) and I'll post the engine data from it. I'll also give a link to the avialogs page http://www.avialogs.com/viewer/avialogs-documentviewer.php?id=2520
Also SOH is still slow as fark for me....
View attachment 5362
Also SOH is still slow as fark for me....
View attachment 5362
Blood_Hawk23
Charter Member
Allen,
Hey man you found the answer. the 16+ and 18+ are the "Through the gate" WEP or 110% power. how ever you want to think of it.
So the answer is a yes and no.
First, NO, as we all know the Merlin didn't use the Water Injection or Water Methanol Injection types of WEP Boost.
Yes it did have an extra power setting. Some would call it 110% Power. So it would have used the Supercharger Boost Increase.
Though I didn't see a time limit for use. I'll have to read some more.
Maybe if some one makes a new throttle they could set it so the normal 100% throttle is marked and a redline or 110% is outlined above that.
Kool. now time for bed. I keep staying up too long. Awesome stuff.
Hey man you found the answer. the 16+ and 18+ are the "Through the gate" WEP or 110% power. how ever you want to think of it.
So the answer is a yes and no.
First, NO, as we all know the Merlin didn't use the Water Injection or Water Methanol Injection types of WEP Boost.
Yes it did have an extra power setting. Some would call it 110% Power. So it would have used the Supercharger Boost Increase.
Though I didn't see a time limit for use. I'll have to read some more.
Maybe if some one makes a new throttle they could set it so the normal 100% throttle is marked and a redline or 110% is outlined above that.
Kool. now time for bed. I keep staying up too long. Awesome stuff.
Yes it was and it was fairly common in the Luftwaffe. (It was called GM1.)
Most folks dont really understand the differences between Water / Water-Methanol, C3 Einspritzung and GM1.
Here's my take on it FWIW:
First of all, just about every military engine of significance was supercharged.
Ambient air pressure at sea level is around 14.7 PSI or 29.92 inches of Mercury or 1.03 ATA or 760 mm or +0 lb boost.
They all mean the same thing.
When an engine is running at idle on the ground, the throttle plate limits the amount of air going into the engine.
The air pressure outside is 29.92 inches of Mercury (Hg) but the pressure in the intake manifold is more like 5-10 in Hg.
If you open the throttle all the way (Wide Open Throttle or WOT) on a non-supercharged engine, the intake manifold pressure rises to 29.92 in Hg and will go no higher.
Superchargers
On a supercharged engine, the supercharger provides additional air pressure to to the engine. On something like a Late model Merlin, you might see something like 60-70 inches Hg. Lets use 60 inches Hg as a limit for this example.
The supercharger can supply more pressure than that, but the engine might detonate (ping) or overheat or otherwise damage itself.
As the altitude increases, the ambient (outside) air pressure drops. The supercharger makes up the difference so that the engine is still sees 60 inches Hg manifold pressure. The excess capacity is just wasted. On a turbo, the extra exhaust is vented out a "waste gate".
At SOME altitude, the supercharger running at full capacity can still maintain sea-level boost (60 inches Hg) but the excess capacity has all been used to make up for the lower ambient air pressure. This is the engine's "Critical Altitude". Above this altitude, the supercharger cannot maintain full boost and engine power falls off. (Usually the aircraft's instake faces into the airflow and the dynamic pressure adds a little boost which raises the critical altitude by a few thousand feet. This is called "Ram-Effect.)
Power Adders - Anti Detonant
If the intake air and fuel (charge) were cooled a bit, a slightly higher throttle setting could be used without detonating, overheating or otherwise breaking the engine. Squirting some Water, Water-Methanol, or extra fuel into the intake does that to some extent.....
....Up to a point. If the supercharger can supply the additional boost / pressure, you can use your "War Emergency Power". Above critical altitude, the supercharger does not have extra capacity and MW50, C3 Injection, or Water Injection can provide no gain.
Higher octane fuel acts also acts as a anti-detonant.
Power Adders - Oxidizers
Above the aircraft's critical altitude, the supercharger cannot supply as much air as the engine can use, but the fuel delivery has not been affected by the change in altitude from ground level. Nitrous Oxide, NoS, or GM1 if fed into the intake will provide additional Oxygen for combustion. In effect, it is an additional supercharger in a bottle. Below critical altitude, it can't add anything because the supercharger already has all the capacity the engine can use. On the FW 190A models that were equipped with GM1, its use was for altitudes over 8 km.
Pardon the long winded reply.
Hopefully it all makes sense.
- Ivan.
kelticheart
Charter Member
Errata corrige
I am very sorry gentlemen, but I have to adjust some of what I wrote above, since speaking "off the top of my head" this time didn't work very well for me.
I have Mr. Avery's book in front of me, and I am sorry again, because my scanner yesterday decided to give me hell. Otherwise, it was my intention to post the scanned pages here.
I quote from the NAA NA-73/NA-126 P51/F-51 Mustang F-6/A-36 Invader chapter of "North American Aircraft 1934-1998 Vol.1" ISBN 091332-05-9, by Norm Avery:
"....Smooth, reliable and well-liked, the Allison engine lacked only the high altitude performance required for bomber escort over Europe. Even so, Allison Mustangs based in Britain were the first Allied fighters to penetrate Germany and also served in North Africa, India and Burma..........As the war in Europe heated up in 1940, Britain authorized the manufacture of the Merlin in the US as the V-1650. The Packard Motor Car Co., one of several automobile manufacturers selected to produce aircraft engines, began building Merlins in 1941......
....USAAF Major Hitchcock, later killed testing a Merlin-powered Mustang, was one of the foremost proponents of the plan (to replace the Allison with the Merlin). The idea quickly gained momentum. Two NA-91 P51s, 41-37352 and 41-37421 were set aside for conversion by NAA with Packard-built V-1650s under charge # NA-101, XP-78, a designation later changed to XP-51B. Two Packard-Merlins were dispatched to NAA so that work could proceed immediately (time frame: first half of 1942). In Britain a similar project, involving five Mustangs with different installation details, was begun by Rolls-Royce at Hucknall in July, 1942.....
....Changes to the airframe were extensive and required considerable wind-tunnel testing. The Merlin, 350lbs heavier than the Allison and even more so with the 4-blade propeller, had a significant effect on weight and balance. In addition, a larger radiator and a new cooling-duct system were required. To accommodate the Merlin's up-draft carburetor the induction duct was moved from above to below the engine. The results of the wind-tunnel tests necessitated moving the cooling-air intake duct about an inch below the boundary layer to provide smooth flow to the radiator and eliminate "duct-rumble". The first Rolls-Royce conversion, on Mustang MkI AL975-G, was flown on 10-13-1942 by Rolls-Royce chief test pilot Capt. R.T. Sheperd and showed a top speed of 427mph. After internal airflow problems were solved, the airplane reached 432mph @20,000' and the climb exceeded original estimates. The other airplanes were completed and flown by 02-03-1943.
Britain had already decided to acquire Inglewood-built NA-102 Merlin-powered Mustangs IIIs (P-51Bs), ordering 400 on 08-26-1942. NAA test pilot Bob Chilton flew 41-37352 on 11-30-1942 and, on a later flight, achieved a top speed of 441mph @29,800' and a rate of climb of 3,600' per minute."
Well, I thus corrected my previous imprecise statements. Thank you for your patience.
Back to this thread topic, I thoroughly read my "Jane's Fighting Aircrafts of WWII" in the "World Aero Engines" section and found that, on top of describing the engine down to the materials used to build it, it lists all of the RR Merlin versions in a table, which include Merlin #, power rating at various altitudes, engine displacement in both liters and cubic inches, compression ratio and aircrafts which any of the versions equipped. Another source I wanted to scan and post here....
The engine description, when it comes to supercharging, speaks only of the Merlin compressor equipment up to the 60-series dual-speed, dual-stage unit. There is no mention whatsoever of WEP equipment, as it was meant in WWII, in any of the Merlin engines manufactured from the beginning to the end of all production runs, including the license-built engines in the U.S.
According to this source, then, Merlin engines were never equipped with WEP.
Cheers!
KH
I am very sorry gentlemen, but I have to adjust some of what I wrote above, since speaking "off the top of my head" this time didn't work very well for me.
I have Mr. Avery's book in front of me, and I am sorry again, because my scanner yesterday decided to give me hell. Otherwise, it was my intention to post the scanned pages here.
I quote from the NAA NA-73/NA-126 P51/F-51 Mustang F-6/A-36 Invader chapter of "North American Aircraft 1934-1998 Vol.1" ISBN 091332-05-9, by Norm Avery:
"....Smooth, reliable and well-liked, the Allison engine lacked only the high altitude performance required for bomber escort over Europe. Even so, Allison Mustangs based in Britain were the first Allied fighters to penetrate Germany and also served in North Africa, India and Burma..........As the war in Europe heated up in 1940, Britain authorized the manufacture of the Merlin in the US as the V-1650. The Packard Motor Car Co., one of several automobile manufacturers selected to produce aircraft engines, began building Merlins in 1941......
....USAAF Major Hitchcock, later killed testing a Merlin-powered Mustang, was one of the foremost proponents of the plan (to replace the Allison with the Merlin). The idea quickly gained momentum. Two NA-91 P51s, 41-37352 and 41-37421 were set aside for conversion by NAA with Packard-built V-1650s under charge # NA-101, XP-78, a designation later changed to XP-51B. Two Packard-Merlins were dispatched to NAA so that work could proceed immediately (time frame: first half of 1942). In Britain a similar project, involving five Mustangs with different installation details, was begun by Rolls-Royce at Hucknall in July, 1942.....
....Changes to the airframe were extensive and required considerable wind-tunnel testing. The Merlin, 350lbs heavier than the Allison and even more so with the 4-blade propeller, had a significant effect on weight and balance. In addition, a larger radiator and a new cooling-duct system were required. To accommodate the Merlin's up-draft carburetor the induction duct was moved from above to below the engine. The results of the wind-tunnel tests necessitated moving the cooling-air intake duct about an inch below the boundary layer to provide smooth flow to the radiator and eliminate "duct-rumble". The first Rolls-Royce conversion, on Mustang MkI AL975-G, was flown on 10-13-1942 by Rolls-Royce chief test pilot Capt. R.T. Sheperd and showed a top speed of 427mph. After internal airflow problems were solved, the airplane reached 432mph @20,000' and the climb exceeded original estimates. The other airplanes were completed and flown by 02-03-1943.
Britain had already decided to acquire Inglewood-built NA-102 Merlin-powered Mustangs IIIs (P-51Bs), ordering 400 on 08-26-1942. NAA test pilot Bob Chilton flew 41-37352 on 11-30-1942 and, on a later flight, achieved a top speed of 441mph @29,800' and a rate of climb of 3,600' per minute."
Well, I thus corrected my previous imprecise statements. Thank you for your patience.
Back to this thread topic, I thoroughly read my "Jane's Fighting Aircrafts of WWII" in the "World Aero Engines" section and found that, on top of describing the engine down to the materials used to build it, it lists all of the RR Merlin versions in a table, which include Merlin #, power rating at various altitudes, engine displacement in both liters and cubic inches, compression ratio and aircrafts which any of the versions equipped. Another source I wanted to scan and post here....
The engine description, when it comes to supercharging, speaks only of the Merlin compressor equipment up to the 60-series dual-speed, dual-stage unit. There is no mention whatsoever of WEP equipment, as it was meant in WWII, in any of the Merlin engines manufactured from the beginning to the end of all production runs, including the license-built engines in the U.S.
According to this source, then, Merlin engines were never equipped with WEP.
Cheers!
KH