On the topic of Thunderbolts

[MiloMorai]

On the oily P-47

 

Republic P-47 Thunderbolt of 1st Lt. Edwin L. King.King was lucky to make it back to base after his plane had an oil line cut by flak while strafing near Brescia,Italy on Jan. 12,1945. The engine seized as he was landing. He is from the 347th FS, 350th FG, 12th AF.

[=362nd_FS=RoflSeal]

1 hour ago, MiloMorai said:

Drain the oil from your car and tell me how long the engine lasts.

A decent amount of time

 

 

 

[Gambit21]

It takes a time for an engine to get to actual ZERO oil.

Drain the pan, and you still have a lining/interface of oil coating the surfaces for a time.

How long that lasts depends on various factors. Point is - oil drained doesn't necessarily result in the engine instantly blowing up.

 

I know my old Chevy didn't like it though. I remember making a 3 hour drive, stopping to add oil every 20 miles.

[ZachariasX]

15 minutes ago, Gambit21 said:

Drain the pan, and you still have a lining/interface of oil coating the surfaces for a time.

Yes, minutes. As seen in the videos above. That is a good base for self confidence over Berlin, huh?

 

With cars... you know.. these sounds, they first appear in idle, but then more and more at higher revs. And then these highway ramps... get so long... Making you wonder whether you will make it to a place where the whole after work traffic will make it past you... 

 

You know now why the Aston DB6 has 13.2 litres of engine oil. As a common rule for (the good old) British cars is that if they are not leaking oil, then it is about bloody time for a refill!

[CountZero]

5 hours ago, MiloMorai said:

On the oily P-47

 

Republic P-47 Thunderbolt of 1st Lt. Edwin L. King.King was lucky to make it back to base after his plane had an oil line cut by flak while strafing near Brescia,Italy on Jan. 12,1945. The engine seized as he was landing. He is from the 347th FS, 350th FG, 12th AF.

 

That means he was able to fly for almost 200km back to his base in Pisa area, not bad for damaged engine P-47D

[DSR_A-24]

12 hours ago, 77.CountZero said:

 

That means he was able to fly for almost 200km back to his base in Pisa area, not bad for damaged engine P-47D

This could be considered an extreme case, but who's to say the current durability of Radial engines isn't at the lowest possible extreme? Since this is a simulator there should be at least some reflection of radial engine durability in real life. A notable difference at the minimum.

[Georgio]

23 hours ago, MiloMorai said:

Drain the oil from your car and tell me how long the engine lasts.

 

Seem to remember there was an instance of a Land Cruiser in Aussie that lost all it's oil and managed to drive out of the interior to safety. 

Another shot of the same jug.

[-TBC-AeroAce]

17 hours ago, Georgio said:

 

Seem to remember there was an instance of a Land Cruiser in Aussie that lost all it's oil and managed to drive out of the interior to safety. 

Another shot of the same jug.

 

Have you seen the Top Gear where they abuse a Land Cruiser and they manage to get it started every time with just basic tools. Just a few things they did was leave it in the sea overnight and put it on top a 40 story building that was blown up. All I'm saying is that is one rugged vehicle. 

Edited October 19, 2018 by AeroAce

[LuftManu]

I can't wait to fly this thing. The turbosupercharger will for sure be someting interesting to play with and learn. I don't expect nothing less than somethig of great quality as they always deliver that 

[Legioneod]

So I've been doing some research to get an estimate of what performance our P-47 will have in game but there are a few things I'm curious about.

 

The P-47 test in question state that the test were done in combat conditions. My question is does combat conditions mean wing racks were installed? or was it clean?

Also, how much speed will you gain by going clean?

Edited October 19, 2018 by Legioneod

[Gambit21]

Don Bryan of the 352nd had his crew modify something his Jug engine (Little One) to boost speed. I wish I could remember exactly what he said they did.

 

At some point I’ll listen through my phone interview and find out - I’m curious.

[Legioneod]

I'm having some trouble figuring out the speed loss with wing racks.

 

The D-22 with wing racks at 65" at 25k ft is about 439 mph. Without wing racks it is around 443 mph (from what I've gathered)

That's only a loss of 4 mph. Are wing racks really this insignificant or am I missing some important data.

 

[CountZero]

7 hours ago, Legioneod said:

I'm having some trouble figuring out the speed loss with wing racks.

 

The D-22 with wing racks at 65" at 25k ft is about 439 mph. Without wing racks it is around 443 mph (from what I've gathered)

That's only a loss of 4 mph. Are wing racks really this insignificant or am I missing some important data.

 

just check what game speck say for other airplanes we have in game with wing racks and:

estimated speed loss with wing bomb racks on lagg3, la5s and yaks is 12kmh, and thouse bomb racks are smaller then on p-47s, for rocket racks is 17kmh
also racks for 4xrockets on p-40 on each wing, in game estimated speed loss is 10kmh 

 

so looking at size of ones on p-47 i would expect mutch more speed loss then just 4mph, when you have just bomb racks on wings

[Legioneod]

32 minutes ago, 77.CountZero said:

just check what game speck say for other airplanes we have in game with wing racks and:

estimated speed loss with wing bomb racks on lagg3, la5s and yaks is 12kmh, and thouse bomb racks are smaller then on p-47s, for rocket racks is 17kmh
also racks for 4xrockets on p-40 on each wing, in game estimated speed loss is 10kmh 

 

so looking at size of ones on p-47 i would expect mutch more speed loss then just 4mph, when you have just bomb racks on wings

Agreed, I figured it would be closer to 11-15 mph loss, but I can't find any solid information except for top speeds, and the difference between top speeds with vs without racks seems to be minimal.

Of course, some of the information regarding the speed could be incorrect, I'll have to keep looking.

 

EDIT: For anyone interested here is a short list of speed at altitude for P-47D at 65" (Keep in mind these may not be exact but it is within the ballpark of what we should see in-game)

 

(Speed is without wing racks)

 

5k ft / 369 mph

10k ft / 387 mph

15k ft / 401 mph

20k ft / 417 mph

25k ft / 429 mph

30k ft / 442 mph

Edited October 20, 2018 by Legioneod

[CountZero]

for mc202 racks say 7kmh loss, and for 4x55 racks on 190a5 loss is 39kmh ! lol thats big

[Legioneod]

39 minutes ago, 77.CountZero said:

for mc202 racks say 7kmh loss, and for 4x55 racks on 190a5 loss is 39kmh ! lol thats big

That's pretty significant.

 

Whats also interesting is the speed loss at 65" with vs without water. You actually can gain about 8mph when using water injection at 65" vs without using it. I'm curious to see if this will be implemented in-game.

Of course, with 130 fuel, water injection was required at 65" so we likely wouldn't see a difference. Water injection isn't required at 65" when using 150 fuel so we'd be more likely to notice a difference if we ever get 150 fuel.

[Legioneod]

I really hope we get a Razorback one day.

 

Look how beautiful this is.

 

[CountZero]

looks good from outside but when playing inside cockpit i would rather be in bubble one we will get, better all around views. I guess if they do pto maybe razerback show it self there, where and when it was used in pto scenarious ?

[Legioneod]

9 minutes ago, 77.CountZero said:

looks good from outside but when playing inside cockpit i would rather be in bubble one we will get, better all around views. I guess if they do pto maybe razerback show it self there, where and when it was used in pto scenarious ?

Was used all over the pacific up until the end of the war.

I hope to see a Razorback as a collector aircraft for Bodenplatte but I doubt we'll see it anytime soon.

Still, I'm just glad we are getting a P-47 at all.

 

I actually don't mind the cockpit too much. What the Razorbacks lacked in visibility they made up for in performance, overall they were slightly better performing than the bubbletop D blocks.

Edited October 20, 2018 by Legioneod

[Talon_]

On 10/19/2018 at 4:44 PM, Gambit21 said:

Don Bryan of the 352nd had his crew modify something his Jug engine (Little One) to boost speed. I wish I could remember exactly what he said they did.

 

At some point I’ll listen through my phone interview and find out - I’m curious.

 

Adjusted the waste gate to divert more exhaust to the turbine for a given throttle setting, effectively running at higher MAP thanks to the turbine spinning harder than normal. The R-2800 could take it.

[ZachariasX]

1 hour ago, Talon_ said:

 

Adjusted the waste gate to divert more exhaust to the turbine for a given throttle setting, effectively running at higher MAP thanks to the turbine spinning harder than normal. The R-2800 could take it.

Does this make sense? Only at high altitude I would guess?

 

„Default settings“ should well have the turbine spin faster than allowed should you push turbo lever all the way forward at low (there you don’t do that at all) to mid altitude. It is very easy to overspeed the turbine below 7000 meters. Bearing temperatures are also a critical value for turbochargers.

[PainGod85]

1 hour ago, ZachariasX said:

Does this make sense? Only at high altitude I would guess?

 

„Default settings“ should well have the turbine spin faster than allowed should you push turbo lever all the way forward at low (there you don’t do that at all) to mid altitude. It is very easy to overspeed the turbine below 7000 meters. Bearing temperatures are also a critical value for turbochargers.

 

No, only at low-medium altitudes. The higher your turbo RPM, the lower your critical altitude for a given manifold air pressure.

 

The R-2800 was one hell of a sturdy engine. The C series took up to 150" of MAP during engine testing, producing 3800 hp (The same engine would be cleared for up to 72" wet, go figure). The damn thing was so sturdy P&W's engineers laughed at the USAAF's acceptance trials for newly manufactured engines.

[Bremspropeller]

7 hours ago, 77.CountZero said:

I guess if they do pto maybe razerback show it self there, where and when it was used in pto scenarious ?

 

Google "Neel Kearby".

It was basicly used everywhere the USAAF fought. The RAF used it, too.

 

7 hours ago, Legioneod said:

What the Razorbacks lacked in visibility they made up for in performance, overall they were slightly better performing than the bubbletop D blocks.

 

There were a handfull of Malcolm-hooded P-47s, but it seems like the mod was never really popular.

 

[ZachariasX]

9 hours ago, PainGod85 said:

 

No, only at low-medium altitudes. The higher your turbo RPM, the lower your critical altitude for a given manifold air pressure.

 

The R-2800 was one hell of a sturdy engine. The C series took up to 150" of MAP during engine testing, producing 3800 hp (The same engine would be cleared for up to 72" wet, go figure). The damn thing was so sturdy P&W's engineers laughed at the USAAF's acceptance trials for newly manufactured engines.

Impressive indeed.

 

What I don't understand in the case mentioned, is that the turbocharger remains the same and hence I would expect critical altitude remaining the same, no matter how you set your minimal turbo rpm. (There is a lower limit to it, you have to control that with the turbo lever, keeping the yellow control light flashing.) The turbocharger doesn't have a smaller diameter to be run at higher speeds (plus better bearings!) by changing the "gearing of the rotor". In the Thunderbolt, the turbocharger is red lined at 20'000 rpm, allowing a 5 minute "WEP setting" (yes, we'll have THAT discussion there AGAIN) at 22'000 rpm. You can easily reach this blower rpm with the normal wastegate valve setting up to mid altitudes. You can absolutely reach 150'' "for takeoff" with any Thunderbolt if you just advance turbo lever on the ground after giving full power on the throttle lever.

 

As I understand it, the critical altitude is limited/set by the 20'000 rpm of the supercharger rotor. Once you have reached that altitude (around 8 km), MAP will drop with increased altitude. The diameter of the rotor inside the turbochager is set such that it matches the maximum rpm tolerated by the bearings (for not overheating) to produce enough air for max. permissible MAP at the defined critical altitude. Thus, I would decrease the critical altitude by making the rotor diameter smaller, as it would produce less air at the same 20'000 rpm at the benefit of having a mildly better spin up chariactersitic (although stlll abyssmal in case of the Thunderbolt, as the piping to the blower and back is more like "pipelines"). Only with having a smaller rotor, I'd have lower critical altitude.

 

 

[Bremspropeller]

1 hour ago, ZachariasX said:

Thus, I would decrease the critical altitude by making the rotor diameter smaller, as it would produce less air at the same 20'000 rpm at the benefit of having a mildly better spin up chariactersitic (although stlll abyssmal in case of the Thunderbolt, as the piping to the blower and back is more like "pipelines"). Only with having a smaller rotor, I'd have lower critical altitude.

 

An interesting point there!

I wonder if they could have benefitted from a two-stage design (more mass anyway, but split between the stages - sort of like in today's cars) or if that was too far fetched at the time.

I'm also wondering about the pressure-loss due to the ducting and piping. There probably is a document about that somewhere - the question is where :)

[ZachariasX]

3 minutes ago, Bremspropeller said:

 

An interesting point there!

I wonder if they could have benefitted from a two-stage design (more mass anyway, but split between the stages - sort of like in today's cars) or if that was too far fetched at the time.

I'm also wondering about the pressure-loss due to the ducting and piping. There probably is a document about that somewhere - the question is where

The arrangement with the R-2800 should give plenty of exhaust to power the rotor, so i doubt any little leaking would be a problem.

 

The spin up time (turbo lag) is not that much of an issue in general flight, as you have to be careful anyway not to overspeed the rotor. In the P-47D, there is a little gauge on the upper left side of the dash showing turbine rpm. You have to have a good eye on that anyway. To the lower left of that gauge is the yellow "blinkenlight".

 

The connection of turbo and throttle lever is only permitted above 7000 feet. Below that you have all the power you need from the engine alone. Besides that, you will be too far back on the throttle to make use of the turbo to good effect. The main use of connecting the levers is making it easier for formation flying. The turbo has significant lag making retaining of your position diffcult. If you connect the levers, small changes on the throttle will be felt more immediately. It is not something that makes the engine efficient, it just makes things easy.

 

It is of note that I don't see this gauge on many photos of P-47 instrument panels. In many restored planes, the turbocharger is not installed/functionel, hence they can use that part of the panel for more useful things like a Garmin. The arrangement (and gauge scaling) differs amongst the different types of the P-47, as seen here:

http://www.avialogs.com/index.php/en/aircraft/usa/republic/p-47thunderbolt/aaf-51-127-3-pilot-training-manual-for-the-p-47-thunderbolt.html#download

on page 13. They don't een show where the gauge is placed on the dash.

 

The P-47 does have an intercooler. The positon indicator has a nice mark for "neutral", so you know where to set it for least drag while retaining sufficient cooling (page 12). If you are at high speeds (350 mph+), you MUST set it to neutral. Thus, you have what you need for practical MAP.

 

Making the turbo two stage won't really cut it, as you'd have a "tripple turbo" arrangemnet then, allowing for two intercoolers. The BMW F11 and F12 5-series cars (the previous m550d) have this, but they pump up to 3 ata to the 3L Diesel engine and they need the extra air cooling. Now in that model, they have "quad-turbo", 2 for 3 cyilinders each. If turbo lag is an issue, that is what commonly is done: you have two turbos that each feed half the cylinders. You keep rotors small for reduction of the spin-up as well as making the turbo more efficient. Many "bi-turbo" work like that.

[Legioneod]

34 minutes ago, ZachariasX said:

 

It is of note that I don't see this gauge on many photos of P-47 instrument panels. In many restored planes, the turbocharger is not installed/functionel, hence they can use that part of the panel for more useful things like a Garmin. The arrangement (and gauge scaling) differs amongst the different types of the P-47, as seen here:

http://www.avialogs.com/index.php/en/aircraft/usa/republic/p-47thunderbolt/aaf-51-127-3-pilot-training-manual-for-the-p-47-thunderbolt.html#download

on page 13. They don't een show where the gauge is placed on the dash.

 

Turbo RPM gauge wasn't added to the instrument panel until later P-47s, earlier ones just used the light from what I've read.

 

Speaking of instrument panels, does anyone have any information on the D-22 panel? I plan on making a model of it soon and I need to find some references. I've never been able to find any photos of it and none exist today. Any help would be appreciated

 

The panels seemed to have remained unchanged for most of the D production, it's not until you get to the D-30 that you see significant changes. Of course some gauges are swapped or changed but the basic layout seems to have remained the same.

 

 

D-15 panel 

.

D-28 Panel

Edited October 21, 2018 by Legioneod

[ZachariasX]

52 minutes ago, Legioneod said:

Turbo RPM gauge wasn't added to the instrument panel until later P-47s, earlier ones just used the light from what I've read.

 

Speaking of instrument panels, does anyone have any information on the D-22 panel? I plan on making a model of it soon and I need to find some references. I've never been able to find any photos of it and none exist today. Any help would be appreciated

 

.

A2A simulations have a very, very nice P-47 for FSX. It is a D-22 and D-23. You can look for such screenies.

[Bremspropeller]

1 hour ago, ZachariasX said:

The arrangement with the R-2800 should give plenty of exhaust to power the rotor, so i doubt any little leaking would be a problem.

 

I was more concerned about the wall-losses and how much pressure was lost pushing the air through the pipes.

 

1 hour ago, ZachariasX said:

The spin up time (turbo lag) is not that much of an issue in general flight, as you have to be careful anyway not to overspeed the rotor.

 

Depends - if you're in low cruise and you're getting bounced, you'll need a quick response time and you'll have to watch the turbo-gauge. Time for those chameleon-eyes.

[Legioneod]

1 hour ago, ZachariasX said:

A2A simulations have a very, very nice P-47 for FSX. It is a D-22 and D-23. You can look for such screenies.

I've seen it but I'd take that cockpit with a grain of salt, quite a few things are incorrect from what I can see.

[PainGod85]

3 hours ago, ZachariasX said:

Impressive indeed.

 

What I don't understand in the case mentioned, is that the turbocharger remains the same and hence I would expect critical altitude remaining the same, no matter how you set your minimal turbo rpm. (There is a lower limit to it, you have to control that with the turbo lever, keeping the yellow control light flashing.) The turbocharger doesn't have a smaller diameter to be run at higher speeds (plus better bearings!) by changing the "gearing of the rotor". In the Thunderbolt, the turbocharger is red lined at 20'000 rpm, allowing a 5 minute "WEP setting" (yes, we'll have THAT discussion there AGAIN) at 22'000 rpm. You can easily reach this blower rpm with the normal wastegate valve setting up to mid altitudes. You can absolutely reach 150'' "for takeoff" with any Thunderbolt if you just advance turbo lever on the ground after giving full power on the throttle lever.

 

As I understand it, the critical altitude is limited/set by the 20'000 rpm of the supercharger rotor. Once you have reached that altitude (around 8 km), MAP will drop with increased altitude. The diameter of the rotor inside the turbochager is set such that it matches the maximum rpm tolerated by the bearings (for not overheating) to produce enough air for max. permissible MAP at the defined critical altitude. Thus, I would decrease the critical altitude by making the rotor diameter smaller, as it would produce less air at the same 20'000 rpm at the benefit of having a mildly better spin up chariactersitic (although stlll abyssmal in case of the Thunderbolt, as the piping to the blower and back is more like "pipelines"). Only with having a smaller rotor, I'd have lower critical altitude.

 

 

 

No, you're trying to do it the wrong way around. Any given turbocharger has a maximum RPM, below which it can be run at any speed because it has no gearing of any kind and is exhaust driven. For a given MAP, the higher you climb, the higher the turbo's RPM will be to maintain it.

 

Now, if you increase maximum permissible MAP while retaining the same turbocharger system, the turbo will reach its maximum RPM at a lower altitude.

 

There is no special WEP setting for the P-47's turbocharger as turbo RPM is primarily dependant on altitude. Case in point, just by increasing MAP from 56" to 70", you lower the critical altitude of the plane by 8'000 ft, from 31'000 ft to 23'000 ft because that's where the turbocharger's RPM limitation produces a hard cap on engine performance.

 

In the same vein, by reducing MAP to a lower cruise setting, it can be maintained to a higher altitude.

[ZachariasX]

1 minute ago, PainGod85 said:

Now, if you increase maximum permissible MAP while retaining the same turbocharger system, the turbo will reach its maximum RPM at a lower altitude.

 Ah, ok. makes sense. Now I get what you mean.

 

2 minutes ago, PainGod85 said:

There is no special WEP setting for the P-47's turbocharger as turbo RPM is primarily dependant on altitude.

True. But I meant that because there is a 5 minutes overspeed limit at 22'000 rpm stated. This overspeed lifts the critical altitude accordingly and up there makes life of a FW190 more sour. So, figuratively speaking. I just wonder when people start complaining about blowing their turbos due to overspeed.

 

Just now, Legioneod said:

I've seen it but I'd take that cockpit with a grain of salt, quite a few things are incorrect from what I can see.

The problem is, once Republic folded as a company, the entire archive went up in smoke. So much documentation was lost forever then because of that vandalism. As said, most current P-47 dashboards seem to be rather freely arranged. I have no idea where Scott and his crew got the arrangement for their D-22/23 from. But it is indeed very hard to get pictures from those types.

 

57 minutes ago, Bremspropeller said:

I was more concerned about the wall-losses and how much pressure was lost pushing the air through the pipes. 

I would speculate that they had a more relaxed approach to such. Just make the blower big enough and you'll have plenty of air for the engine. That is the advantage of the size of the  Thunderbolt. Instead of adding tailgunners, waist gunners and belly gunners, in that space they added a supercharger.

 

1 hour ago, Bremspropeller said:

Depends - if you're in low cruise and you're getting bounced, you'll need a quick response time and you'll have to watch the turbo-gauge. Time for those chameleon-eyes.

The only thing you can do in that case is roll and dive. You can think of engine management at this point. Working the throttle like in a Spitfire won't help you too much with that weight. Rolling on the other hand it will do better then the 109. But on the other hand, you get a feeling for maximum turbo lever position, depending on altitiude. You can move it forward quickly to that point. Depending on your engine power setting, that might take one or two seconds for MAP to develop.

 

[PainGod85]

7 hours ago, ZachariasX said:

 Ah, ok. makes sense. Now I get what you mean.

 

True. But I meant that because there is a 5 minutes overspeed limit at 22'000 rpm stated. This overspeed lifts the critical altitude accordingly and up there makes life of a FW190 more sour. So, figuratively speaking. I just wonder when people start complaining about blowing their turbos due to overspeed.

 

Actually, it's a 15 minute limit at 22'000 RPM: http://www.avialogs.com/index.php/en/aircraft/usa/republic/p-47thunderbolt/an-01-65bc-1a-pilots-flight-operating-instructions-for-p-47d-25-26-27-28-30-and-35-airplanes.html#download

E: Document page 36, section III.

E2: Just to cover my bases, the P-47's engine isn't turbocharged, it's turbosupercharged. The R-2800 always comes with a mechanically driven supercharger impeller installed behind the two cylinder rows.

Edited October 21, 2018 by PainGod85

[catchthefoxes]

Super quick question: does the D 28 have instrument lights?

[Legioneod]

31 minutes ago, catchthefoxes said:

Super quick question: does the D 28 have instrument lights?

Yes, light switches are located on the switch panel below the throttle quadrant.

Edited October 21, 2018 by Legioneod

[BornToBattle]

Hmmm...

 

...from Wiki, wonder if this will be modeled? Skip bombing. Wasn’t aware that you could even skip a 500 pound bomb across water, let alone on land. 

 

P-47 pilots frequently carried two 500 lb (227 kg) bombs, using skip bombing techniques for difficult targets (skipping bombs into railroad tunnels to destroy hidden enemy trains was a favorite tactic).

Edited October 23, 2018 by BornToBattle

[357th_Dog]

B-25's used skip bombing against Japanese ships in the Pacific all the time with the 500's...

I don't think IL2 has that modeled (yet?) ...bombs just kind of splash into the water no matter the delivery angle.. 

[Diggun]

Skip bombing works just fine.

[LukeFF]

56 minutes ago, JohanLoton said:

I don't think IL2 has that modeled (yet?) ...bombs just kind of splash into the water no matter the delivery angle.. 

 

 

[DD_Arthur]

1 hour ago, BornToBattle said:

(skipping bombs into railroad tunnels to destroy hidden enemy trains was a favorite tactic).

 

As was bouncing fifty cals off of roads to penetrate the undersides of Tiger tanks!