P47 vs P51

[reece146]

3 hours ago, brucewhf said:

P47 is  really really really bad at dogfight. 

You might be doing it wrong...

[grafspee]

Problem in p47 is that, to acquire max power, lots of switches and levers had to be moved and pilot has to monitor temps and regulate cooling in other warbirds one lever full on and that's it.

[Katj]

Problem in p47 is that, to acquire max power, lots of switches and levers had to be moved and pilot has to monitor temps and regulate cooling in other warbirds one lever full on and that's it.

What switches and levers are those?

[grafspee]

Oil cooler switch inter cooler switch, boost lever, throttle lever, cowl flaps, water injection switch, then you need to watch MP, heads temp, oil temp, carb temp all the time to not exceed limits, no automatic temp or boost regulators, you can over boost engine and kill it very fast. In other warbirds in DCS excluding I-16 every thing is automated.

Ofc you can wide open all but this creates more drag and slows plane down so automated cooling is great deal.

Edited June 22, 2022 by grafspee

[peachmonkey]

44 minutes ago, grafspee said:

you can over boost engine and kill it very fast.

I only managed to do that at 28,000 ft when the turbo over-sped and I didn't see the barely noticeable warning light, and it was on water as well. I think people may also boost their rpm to 2,700 during the df crisis and that extra 100 rpm is indeed a complete and utter killer. I stopped going above 2,600 altogether, and the engine stays totally fine for 15 mins with max throttle/max turbo<22,000/fully open oil rads/air rads with water injection.

Edited June 22, 2022 by peachmonkey

[grafspee]

8 minutes ago, peachmonkey said:

I only managed to do that at 28,000 ft when the turbo over-sped and I didn't see the barely noticeable warning light, and it was on water as well. I think people may also boost their rpm to 2,700 during the df crisis and that extra 100 rpm is indeed a complete and utter killer. I stopped going above 2,600 altogether, and the engine stays totally fine for 15 mins with max throttle/max turbo<22,000/fully open oil rads/air rads with water injection.

 

over boost =/ over rev turbine

2700rpm is required for higher power, when i fly i can boost above 64 inch with no damage only thing you need to watch stuff

Edited June 22, 2022 by grafspee

[peachmonkey]

3 minutes ago, grafspee said:

over boost =/ over rev turbine

2700rpm is required for higher power, when i fly i can boost above 64 inch with no damage only thing you need to watch stuff

 

ok, so over-boosting is a high altitude risk then

with 2700 rpm I have very little luck. Honestly I'm not that sure of how much more power it can add with everything else maxed out whilst In a close df combat with yo-yo's, scissors, and other loopty-loops.  Now, if I'm chasing someone over long distance there may be the need for it, otherwise it's too risky for me..

[grafspee]

1 hour ago, peachmonkey said:

ok, so over-boosting is a high altitude risk then

with 2700 rpm I have very little luck. Honestly I'm not that sure of how much more power it can add with everything else maxed out whilst In a close df combat with yo-yo's, scissors, and other loopty-loops.  Now, if I'm chasing someone over long distance there may be the need for it, otherwise it's too risky for me..

Over boost happen when you draw too much MP for given rpm, with P-47 you can easily push 60 inch at very low rpm, at low rpm piston travels slower then at high rpm, ignition timing is unchanged, detonation wave travels at constant speed but at lower rpm piston travels slower so undetonated portion of air fule mixture is subjected to pressure and temp exceeding anti detonation properties of fuel thus creating secondary ignition, this induce extremes pressure and temps in combustion chamber which kills engine, this can not be detected by gauges in cockpit.

Over boost can happen when altitude of plane is changed rapidly , for example in combat when you dive or climb rapidly, in case of P-47 pilot have to constantly watch boost to maintain desired MP, in case P-51 pilot just need to push throttle to the gate that is it. 

Simpler version, when you set max rpm in P-51 you can not over boost, if you set max rpm in P-47 you can over boost

page from P-47 manual

Edited June 22, 2022 by grafspee

[peachmonkey]

12 minutes ago, grafspee said:

Over boost happen when you draw too much MP for given rpm, with P-47 you can easily push 60 inch at very low rpm, at low rpm piston travels slower then at high rpm, ignition timing is unchanged, detonation wave travels at constant speed but at lower rpm piston travels slower so undetonated portion of air fule mixture is subjected to pressure and temp exceeding anti detonation properties of fuel thus creating secondary ignition, this induce extremes pressure and temps in combustion chamber which kills engine, this can not be detected by gauges in cockpit.

Over boost can happen when altitude of plane is changed rapidly , for example in combat when you dive or climb rapidly, in case of P-47 pilot have to constantly watch boost to maintain desired MP, in case P-51 pilot just need to push throttle to the gate that is it. 

agreed on all points. However, in my personal experience with dog fights in DCS MP is 99% of the time they happen at a pretty low altitude with a rather short altitude changes, again, it's my personal experience, which I'm sure is limited, i.e. i'm commenting from my use case specifically. And in those 99% of the time every time I used 2700 with water injection the engine died within 30 seconds at 100% of the time used. Yet doing it on 2600 was perfectly fine 100%. Call it a simulation gap, perhaps, but that's really the only reason why I stopped using 2700 at all, it doesn't look like its worth the time.

Your commentary is making me think all sorts of tactics right now and I will definitely revisit the 2700 dilemma soon enough.... Hopefully i'm wrong and i'm simply making some mistake in the process.

edit: although even with 2700 working I still doubt there is going to be that much of a difference in the actual dog fight. If you are bounced and damaged then it won't matter, if you are bounced and not damaged then the tactics are 99.9% and the extra 100rpm is the remaining 0.1%, which is .. yup. And if you are an attacker the tactics are 99.99% and that extra power burst won't help a zilch.

 

Edited June 22, 2022 by peachmonkey

[grafspee]

8 minutes ago, peachmonkey said:

agreed on all points. However, in my personal experience with dog fights in DCS MP is 99% of the time they happen at a pretty low altitude with a rather short altitude changes, again, it's my personal experience, which I'm sure is limited, i.e. i'm commenting from my use case specifically. And in those 99% of the time every time I used 2700 with water injection the engine died within 30 seconds at 100% of the time used. Yet doing it on 2600 was perfectly fine 100%. Call it a simulation gap, perhaps, but that's really the only reason why I stopped using 2700 at all, it doesn't look like its worth the time.

Your commentary is making me think all sorts of tactics right now and I will definitely revisit the 2700 dilemma soon enough.... Hopefully i'm wrong and i'm simply making some mistake in the process.

Difference between 2700 and 2600 rpm is very small, it would impact engine life time only, probably. I was thinking about running engine 60 inch at 2000rpm :). Why engine seems to feel better at 2600rpm then at 2700rpm at high levels of MP is not obvious for me, both 2600 or 2700 should not make a big difference and for sure difference should not be in favor of lower rpm in case extreme MP levels. 

I personally use max rpm, and i managed to muse +64inch of boost, i think have run engine at 70 inch for good 1 min with no damage, but variables are so many, it is hard to establish test bench in DCS

Edited June 22, 2022 by grafspee

[peachmonkey]

Just now, grafspee said:

Difference between 2700 and 2600 rpm is very small, it would impact engine life time only, probably. I was thinking about running engine 60 inch at 2000rpm :). Why engine seems to feel better at 2600rpm then at 2700rpm at high levels of MP is not obvious for me, both 2600 or 2700 should not make a big difference and for sure difference should not be in favor of lower rpm in case extreme MP levels. 

2700 is in the RED danger zone   

yeah, that's why I'm thinking it's either a bug (following the ignition/detonation logic) or we're missing something in the picture. I do remember seeing Yo-Yo's posts from way back warning folks to not lower rpm's abruptly and/or beyond 2000 due to the ignition timing, but that's about it from ED's side. Maybe there's more but I'm not aware of any other info...

[grafspee]

9 minutes ago, peachmonkey said:

2700 is in the RED danger zone   

yeah, that's why I'm thinking it's either a bug (following the ignition/detonation logic) or we're missing something in the picture. I do remember seeing Yo-Yo's posts from way back warning folks to not lower rpm's abruptly and/or beyond 2000 due to the ignition timing, but that's about it from ED's side. Maybe there's more but I'm not aware of any other info...

Red zone is 3050 rpm, 2700 rpm is designed for max dry/wet power, 52inch 2700rpm for dry and 64inch 2700rpm for wet. This looks logical for me, water injection lowers temp of ingestion air fuel mixture this increase effective anti detonation properties of AFM. This topic is not unknow for me, i remember P-51 being able to withstand 67 inch much longer at 2700rpm  then 3000rpm which feels totally wrong for me, why enforce high rpm of the engine when lower rpm is sufficient to take boost, then engine/prop gearing ratio should be changed only.

Edited June 22, 2022 by grafspee

[peachmonkey]

14 minutes ago, grafspee said:

Red zone is 3050 rpm, 2700 rpm is designed for max dry/wet power, 52inch 2700rpm for dry and 64inch 2700rpm for wet. This looks logical for me, water injection lowers temp of ingestion air fuel mixture this increase effective anti detonation properties of AFM. This topic is not unknow for me, i remember P-51 being able to withstand 67 inch much longer at 2700rpm  then 3000rpm which feels totally wrong for me, why enforce high rpm of the engine when lower rpm is sufficient to take boost, then engine/prop gearing ratio should be changed only.

 

I guess I'm going by Chuck's guide and ED's guide. Both state 2800 as MAX RPM, with 2750 having the Red mark.

come to think of it, maybe I was maxing it out to 2750 and that's what is killing the engine. But in VR it's so darn difficult to see it exactly, I almost need to dive to the knee level to see the actual exact reading..

edit: anyway, we seem to have hijacked the thread..   i'll leave this topic for some other time and place, but will do more testing, i'm sure it's all because of my actions...

Edited June 22, 2022 by peachmonkey

[grafspee]

@peachmonkey if you talk about P-47 or P-51 in detail in topic named "P-47 vs p-51", you are not hijack anything in my opinion, anything, even small detail limited to P-47 or P-51 is contribution to the topic anyway.

Edited June 23, 2022 by grafspee

[Katj]

Oil cooler switch inter cooler switch, boost lever, throttle lever, cowl flaps, water injection switch, then you need to watch MP, heads temp, oil temp, carb temp all the time to not exceed limits, no automatic temp or boost regulators, you can over boost engine and kill it very fast. In other warbirds in DCS excluding I-16 every thing is automated.
Ofc you can wide open all but this creates more drag and slows plane down so automated cooling is great deal.

Don't forget mixture and rpm!

No, but seriously, you can mostly set all of the above to the desired state (cruise/combat/whatever) and then forget about them. Of course you still need to watch your temps.


The engine management is part of the charm with the jag, though.

[grafspee]

1 hour ago, Katj said:

Don't forget mixture and rpm!

No, but seriously, you can mostly set all of the above to the desired state (cruise/combat/whatever) and then forget about them. Of course you still need to watch your temps.


The engine management is part of the charm with the jag, though.

Mixture and rpm i didnt mention because i assumed that we are talking about fighting in p47. After you set power in p47 you need to watch and guard MP it will change with speed and alt so you cant forget it, like in p51. If i set 64inch 2700rpm and i do loops i have to constantly adjusting throttle/boost lever to maximize power. Second thing which i forgot to mention that transition from cruise power to combat power is quite tricky, like you said it is easy to forget about mixture, p51 has automated mixture control another thing lifted off pilot's head.

Edited June 23, 2022 by grafspee

[Katj]

Mixture and rpm i didnt mention because i assumed that we are talking about fighting in p47. After you set power in p47 you need to watch and guard MP it will change with speed and alt so you cant forget it, like in p51. If i set 64inch 2700rpm and i do loops i have to constantly adjusting throttle/boost lever to maximize power. Second thing which i forgot to mention that transition from cruise power to combat power is quite tricky, like you said it is easy to forget about mixture, p51 has automated mixture control another thing lifted off pilot's head.

Right, but you don't really have to mess with oil cooler, intercooler, or cowl flaps during combat. At least I never saw the need, but maybe ymmv.

If you want to reduce flight engineer workload you can always link boost and throttle, and then you're pretty much down to using one axis to manage your engine over a very large portion of the envelope.

[grafspee]

1 hour ago, Katj said:

Right, but you don't really have to mess with oil cooler, intercooler, or cowl flaps during combat. At least I never saw the need, but maybe ymmv.

If you want to reduce flight engineer workload you can always link boost and throttle, and then you're pretty much down to using one axis to manage your engine over a very large portion of the envelope.

 

Yes you can do that, but at cost, linked throttle/boost lever reduce engine power, manual says somethin about 300hp which is quite.

True you can set oil cooler, inter cooler wide open and you will be fine, but if you want to maximize P-47 performance you have to manually regulate those, cowl flaps needs least attention but if you end up in slow flight at high power you have to open them manually, then when speed increase close them. 

This is main difference between P-47 and P-51 from system automatization view.

It is much easier to draw max performance from P-51 then from P-47. 

Edited June 23, 2022 by grafspee

[PharaohSteve]

Wish I had found this thread sooner, bought the P-47 and it’s not been much fun. 

[ctguy1955]

   Been practicing landing tail draggers for over 5 years now in DCS.  I still bounce, but never die anymore, I just wreck the prop or a Arm & wheel. 
I was lucky to find someone kind who had Me visit His private server and while He sat in a plane behind Me, He watched My takeoff and told Me
5 percent right rudder !!    I have not taken off in the Dora in a long time, but I made it into the air with no AI help stuff, and it was fun to fly.

   I have both the 51 and 47 ( heck, I have all the WWII planes available ) and end up using the 51 because of speed.  8 50 cal's are better then 6 when inside an iron tub.
try taking a 47 down low with 2 i-6 Russian Planes. Even on ROOKIE setting the 2 of them gang up on You !!! 

  Newest version of OB has lowered my FPS by half of what I was getting with 32235 version.       Lots of DCS Crashes    ( its ok, its OB and I send em my reports )

 i912900K (71 percent OC and water cooled) attached to evga rtx 2080Ti Black Edition that I no longer need to OC using X1 software.

 ROG Strix Z690-E   5200 speed Corsair ram 64gigs

  what a difference with new clouds and it keeps getting better and better !
    Now if only the F4U Corsair would make its presence asap...
       Clear Skies
           Mike