Can not recall

[dirtysidedown430]

Was the 2600 ever fitted with a compound super charger

[Matt Gunsch]

No, only 3350s

[dirtysidedown430]

The 3350 has turbo assisted b17 has compound super charger

[Larry Kraus]

This appears to be an apples and oranges argument. In aviation, Turbo-compound means a specific installation in which exhaust gasses run turbine wheels that are mechanically connected to the drivetrain of the engine. Certain versions of the R3350 are the only truly successful aircraft turbo-compound engines, although the Napier Nomad and a version of the R4360 also used a variation of turbo-compounding.

Compound supercharging is more of an automotive term, although you could consider a radial engine with an internal supercharger and a turbo supercharger as being compounded, although I've never heard it referred to as such in aviation. So everybody is correct, or not.

This link may help

https://en.m.wikipedia.org/wiki/Turbo-compound_engine#

So, to answer your original question (I think), the XF6F-2 used a turbo supercharger with the R2600 engine. There may have been others, but none that went into production that I'm aware of.

Another link

https://commons.m.wikimedia.org/wiki/Fi ... ellcat.jpg

[dirtysidedown430]

well said thanks. I have been told that if its a Wright its wrong wonder if thats why no super charger.

[Larry Kraus]

I've flown B-17's with the Wright R1820-97, which has a single speed internal supercharger and an external turbo supercharger. This is capable of 46" manifold pressure. Also a Super DC-3/C-117D/R4D-8 with Wright R1820-80B engines which also have a single speed internal supercharger that was capable of giving 54.5" manifold pressure for take-off.

I also have several thousand hours in DC-7's with several dash number Wright R3350 Turbo-compound engines that have 2 speed internal superchargers as well as 3 power recovery (blow down) turbines that are exhaust driven and coupled to the engine crankshaft via a fluid drive. We had a limit of 53" manifold pressure for take-off with 100/130 avgas. They are capable of considerably more with 115/145 fuel. I found all of these engines to be very reliable and reasonably trouble free.

[CAPFlyer]

One thing to note - almost all radials in warbirds have a supercharger in them. I've had discussions with several people who swear that the R1820 and R1830 don't have superchargers, but the fact is, they all have a least an induction supercharger at the base of the intake path to maintain positive intake pressure at all power and airspeed conditions. While they may not be a power additive supercharger or a normalized supercharger designed to increase critical altitude, they're still supercharged. Thus, any radial-engined warbird that has a turbocharger is, by definition, turbo-supercharged since there is always that supercharger on the engine.

[Dan K]

Larry's pony.

Last edited by Dan K on Sat Feb 13, 2016 10:28 pm, edited 1 time in total.

[CAPFlyer]

BTW, I had to go lookup what was meant be "Compound Supercharging" before my post because I'd never heard the term in aviation. For those who don't know, the only references I can find is that it is two forms of "supercharging" the airflow in series (rather than in parallel) and can comprise of 2 superchargers, 2 turbochargers, or any combination thereof (in any order, although obviously supercharge then turbocharge has the greatest efficiency). This would mean that 2-speed superchargers don't count, however, I do believe that a 2-stage supercharger (i.e. what the Merlin has) does.

[Larry Kraus]

For CAPFLYER, the most dipomatic thing that I can say about the people who claim that R1820's and R1830's are not supercharged is that they are misinformed, although I can think of a more accurate definition.

Here are some pages from various manuals pertaining to this matter

From a B-24 Erection & Maintenance manual specifically referring to the R1830-43





These pages are from the B-17G Erection & Maintenance manual





And a diagram from the B-17 Pilot Training manual



Even small radials like the R985 have superchargers. This page is from the RCAF Expeditor Flight Manual



I did run across one radial that supports your statement that they all had at least an internal non-supercharging impeller to distribute the fuel/air mixture to the cylinders. Note that the blower ratio on the R680 engines is 1:1 These pages are from a Flight Manual for the AT-9A

[dirtysidedown430]

Boy that was a ton of work thanks

[shrike]

The Jacobs is the only one of the common small/midsize radials NOT to to have a blower for mixture distribution, if not boost.

[CAPFlyer]

Thanks for those pages Larry. I think too many people actually do confuse the turbo and supercharger.

[Larry Kraus]

CAPFlyer,

In 1982 I had a problem with #2 engine on B-17 Tanker 65. It would take more throttle to maintain climb manifold pressure than the other engines with the turbos dialed to number 6 which was our climb power setting (props 2300/turbos to #6/throttles to 38"). After landing, I ran a full throttle power check with the turbos dialed to zero. That normally gave 38" of manifold pressure at Porterville with a field elevation of 444 ft. The other three engines registered the expected 38". #2 engine gave 45".

I figured that there must be a problem with the turbo waste gate on that engine not opening to zero. The turbos were set to give 46" with the turbos dialed to #8 which was the take-off setting. The cockpit controller for the turbos had four pots to adjust the individual engine manifold pressure at full throttle at the #8 setting. I ran the check again with a my co-pilot watching the waste gate on #2 to see how far it closed during the check. He said that it stayed wide open.

That didn't make sense to me, so we disconnected the linkage and safety wired the waste gate open. We still got 45". I called our director of maintenance and that's when I learned that R1820-97 engines will indicate 45" manifold pressure in an engine test stand and it's the ducting for the turbo that reduces the static manifold pressure with turbos at zero to 38". It turned out that there was a massive leak in the ducting between the turbo and the carburetor and #2 was basically getting ram air. The extra throttle in climb was because the internal supercharger couldn't match the extra boost from the turbo during the climb

I had about 800 hours in B-17's at the time. It just shows that you learn something every day. I'd thought that the internal supercharger on the R1820-97 only managed 38" without the turbo. I was correct as far as the installed condition, but wrong as to the potential power available.

[CAPFlyer]

Very interesting information Larry. It definitely is interesting how the engineers of the time overcame some of the problems they ran into when designing the planes.

It's also interesting that this topic came up when it did because I've been involved in a discussion about supercharging (and specifically that of the R1340) over in another forum that started on the same day as this one. One of the things that was brought up was that the R1340 had "mild" supercharging compared to later engines and the person who made that comment used the V1650 (Merlin) as the comparison in that the R1340's max Manifold Pressure of 36" versus the 67" of the Merlin meant the R1340 was capable of much more. I don't think he realized that he was talking about an internally supercharged engine versus an externally 2-speed, 2-stage supercharged one. I do wonder how much more power the R1340 could produce if an external supercharger was applied to it though...