i must admit, I was thinking of a whipple type supercharger like you see on top of a muscle car. No such thing here. uhmmm…
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Oh mate you didn’t have to! Thank you so much!
My mind works the same way. But remember you basically have 3 types of superchargers. Centrifugal Turbocharger - Impeller driven by exhaust gas, Centrifugal Supercharger - impeller driven by mechanical means (belt or gear system), and My personal favorite the roots style like Whipple with the big meshing lobes. Love the sound of these the most. My brother used to have a F150 Lightning back in 04 that had this type. The whine was so throaty and insane. Oh yeah and then you have the coveted electric hair dryer turbo out of china.
I thinks its potato-potato on the nomenclature. Technically they are all Superchargers, this one being a turbo-supercharger. Could be wrong though.
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I found this rather relevant video:
Seems as if the “Boost” Lever controls manifold pressure from the turbo charger. It is recommended to use the full boost available from the engine driven super charger first before activating the additional boost from the turbo.
Maybe it comes with a penalty due to exhaust gas backpressure.
Maybe its just a precaution to prevent overboost at low level.
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https://lynceans.org/all-posts/the-complexity-of-a-ww-ii-p-47-thunderbolts-powerplant/
Also a good article on the P-47 engine with some great shots of the turbo-supercharger system pulled from the plane
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So just a giant turbo stuffed in the rear fuselage, awesome.
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Here you can see the two stage approach: It has both, a turbo charger as the first stage then an intercooler and a super charger/blower as second stage. You can’t really see the super charger in the pictures from Gunny’s link though.
I don’t quite get the argument with the 300 hp. It doesn’t seem as there’s a clutch or gear for the second stage, so there will always be the penalty to drive the super charger.
It’s not uncommon for these late war planes to produce too much boost on ground level. The might explain, why you will usually have the boost lever back at takeoff.
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Well the point is, there is a net gain in power despite what is needed for the supercharger, because increased boost means a much higher gain in power. 50inHg vs 30inHg means an enormous difference in massflow, which is directly proportional to engine power.
Sure. But when you already reach maximum manifold pressure without the turbocharger on the deck, I don’t get the “lose 300 hp” argument from Greg’s Youtube Video:
Moving the throttle and boost levers together can cost you 300 horsepower in this plane! Find out why, how to use the levers, and when to use the throttle and boost lever interconnect.
It’s actually a crude design to control the boost manually, if you think about it. Mr. Messerschmitt and Mr. Tank thought the same, I guess 
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Right, turbochargers don’t consume engine power. The only argument that can be made in this regard is if you have a multi-gear supercharger that is driven in high mode at low altitude.
In the German designs, the superchargers used variable vanes (IIRC) to use only as much torque as was needed to provide the commanded boost.
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THANKS TO @miRage for that pic. I never saw or understood where the Supercharger part was. The turbo is obvious. As for inherent loss from parasidic mechanical links… Truth is, I dont know. 300hp loss seems a lot. But again, we are talking 2800 cubic inches of monster. Some loss must be atributed to the system. Question is does it make up for that loss at low level? We have to try a drag race. I’m really interested in whether to use boost or not in a low level DF. I’m not worried about over boosting. Give me as much power as possible and let Me worry about controlling it.
I need to watch more of Greg’s videos on the Tbolt. The one on the boost lever was really helpful since the DCS manual explained absolutely nothing about its use.
No. The two stage design enables you to keep the maximum allowed manifold pressure up to higher altitudes. If you’d engage the turbo charger down low you will likely encounter the engine’s structual limits (i.e. blown casket or damage to the cylinder heads, valve covers, manifold, etc…)
In the Mustang you can overboost the engine with throttle alone. I don’t have the Jug yet but I’d expect if you slam the throttle to the forward stop during takeoff at sea level, you will exceed maximum manifold pressure even with the Turbo fully back.
It still confuses me why they talk about a loss of hp. As @sobek pointed out it’s inherent of the design, that some power is used to drive the super charger but due to it’s help the overall output is higher than without it.
Yes. Boost has an enormous influence on engine power. If you look at the different versions of the RR Merlin, it went from ~1000HP @ +6psi to ~2000HP @ +25psi in some extreme late production models. Naturally the boost wasn’t the only modification made to enable this big increase, but it has the biggest influence. More massflow = more power. Denser air means more mass, means more fuel can be injected.
Think about the amount of air that is having to be pulled into the intake manifold with no boost. Now, think about how much pressure is going to exerted onto it to compress it down to generate another 20+" of pressure.
A supercharge for a much smaller automotive engine with all the benefits of modern tech can easily take 60 HP or more to feed a 600 CFM engine at say 20" of boost. Now we’re talking an engine displace say 5L’s or (305 cubic inches). The Double Wasp is 2804.5 cubic inches of displacement. The formula to calculate CFM is cubic inches x RPM x volumetric efficiency ÷ 3456 . Any ordinary car engine will have a volumetric efficiency of about 80% (no clue about AC engines honestly, a buddies wife was a AP mechanic, I’ll see if she knows). For the Double wasp that’s about 1750 CFM if it’s just a plain jane naturally aspirated engine. So with triple the displacement we’re talking at LEAST 180 horsepower to generate an additional 20" of boost at sea level, and that’s assuming the horsepower required scales linearly with the amount of air it’s trying to compress (which it doesn’t, but I’m not going to bother looking up a table with that data). The turbo does help offset this somewhat, but I can totally see the 300HP number being well in the ball park.
Don’t forget the heat at any practical level of boost. Cramming that much air down is going to raise the turbo and supercharge temps like a blowtorch in short order. The intercooler can only do so much.
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Here are some facts.
I started out at my spawn point and slowed down to 250mph. At a desigated point I ran up the engine to 2700 RPM and full throttle no boost. From there to my finish point 3:08.
I started agian, this time with full boost. 2700RPM and full boost. 3:01. That is the facts.
While on boost the engine was cooled with flaps open halfway. Not on boost, engine still needed to be cooled. So, okay. You get a good surge in power but your engine really suffers.
I stand corrected. Down low. Go go turbo.
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Nice little practicality test. Also I think the DCS p47 has some engine cooling tweaking to be done. I need to find a way to put the DCS P47 sounds into the IL2 version. The cockpit sounds amazing on the videos ive seen.
In the name of practicality, I did a test over the weekend. I just did not know it was a test. Landing the Jug was tough. But I got to a place where I could walk away (mostly) unhurt. So for comparison I flew the Mustang. I found it a bit easier to fly and land. It really is a Cadillac. For comparison, I flew the 109. I had great fun avoiding the B-17 gunfire and sparring with the Jug and Mustang. But when it came time to land, I realized I had to practice. So I practiced till I was not going to get kicked out of the Luftwaffe. It made me think… How bad is the Spitfire. I was seeing red and decided to let it go until I can have more time to dedicate to it. A couple of days later I flew the Jug again against Doras. It was awesome and I slaughtered them. When It came time to land, I remembered the horrors. But when I touched down I realized. This is the easiest to land of all the Warbirds…
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For me, landing the Jug clicked when I realized two things:
-Airspeed will determine whether you land or crash land
-Final approach requires enough power to get to the threshold. I’ve learned to avoid completely cutting throttle on final
-Once runway threshold is reached, cut throttle and let yourself glide on the runway until the aircraft can’t generate enough lift.
That’s the only way I can get reliable landings. I was also surprised at how much better my landings in the Spitfire and Mustang were after a few weeks practicing in the Jug.
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The Jug is great fun. Thanks for that bit of advice. I for one with have to be coucious of that on final. There are a few things that will make the Thunderbolt complete. First the engine modeling. You can overrev the engine to the moon and back without consequences. There are also no concequences for overheating it. The Cylinder head gauge seems goofy. The relationship between the gauge and the cowl flaps does not jive. Closing the flaps does nothing to bring up the engine temp on the ground. Also the Oil temp seems to quit working sometimes. So controling oil temp is not an option at these times. These are all small things and for an early access the Jug rocks! None of this has kept me from enjoyig the ride. I chalk it all off to early access. My money is well spent. But still I hope these things get resolved soon.
Now about ground attack, I hope the rockets dont go the way of the underwing cannons in the Messer. What ever happened to them? The 109 is such a joy to fly against any opponent and truly a menace to B-17. However, It needs the underwing gondolas as much as the Jug needs its rockets. Since one of the things I enjoy is doing escort in the Jug, external tanks would add a bit of realism to this. You will have to switch off the the external fuel tank valve. Then switch the main valve to Auxiliary. And you better be quick so you dont stall the engine. I would like the added immersion and sence of urgency after spotting bandits or getting bounced.
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