R2800 Engines for the B-17s/B-24s ?

syscom3 · 08-03-2007, 02:42 PM

Quote:

Originally Posted by FLYBOYJ

The factory wasn't the problem, the redesign of the current airframe was the issue as earlier pointed out. Disruption of engineering efforts for engine upgrades on B-17s and B-24s would of been a waste of time, especially when the B-29 and B-32 were coming down the pipe...

I know, I was just commenting that the R2800 engine program could have easily been expanded, in the unlikely event, the B17's and B24's were modified for this engine.

HoHun · 08-03-2007, 04:34 PM

Hi Syscom,

>B29's and B32's got the Wright R3350, and never were considered for -2800's.

Hm, do you know the reason for that? It seems that the R-3350 delivered 2200 HP take-off power in the B-29, which the R-2800 could have matched - and the R-3350 proved to be a rather troublesome engine in early B-29 development while the R-2800 apparently was a mature design at the same time. (At least, that's my impression.)

Regards,

Henning (HoHun)

FLYBOYJ · 08-03-2007, 06:31 PM

Quote:

Originally Posted by HoHun

Hi Syscom,

>B29's and B32's got the Wright R3350, and never were considered for -2800's.

Hm, do you know the reason for that? It seems that the R-3350 delivered 2200 HP take-off power in the B-29, which the R-2800 could have matched - and the R-3350 proved to be a rather troublesome engine in early B-29 development while the R-2800 apparently was a mature design at the same time. (At least, that's my impression.)

Regards,

Henning (HoHun)

The R2800 for the most part was considered a "fighter engine." Although it could of easily been used, it was decided to go with the 3350 which had the power to weight ratio suited for a multi engine aircraft. Additionally the USAAF did have a call in what engine was going to be used in their bomber. After WW2 a number of commercial aircraft used the 3350 because of this.

SoD Stitch · 08-03-2007, 09:59 PM

Quote:

Originally Posted by FLYBOYJ

The R2800 for the most part was considered a "fighter engine." Although it could of easily been used, it was decided to go with the 3350 which had the power to weight ratio suited for a multi engine aircraft. Additionally the USAAF did have a call in what engine was going to be used in their bomber. After WW2 a number of commercial aircraft used the 3350 because of this.

Am I right in saying the DC-4 and DC-5 used the 3350 (as a specific example)?

FLYBOYJ · 08-03-2007, 10:20 PM

Yep - Turbo Compounds....

SoD Stitch · 08-03-2007, 10:23 PM

Quote:

Originally Posted by FLYBOYJ

Yep - Turbo Compounds....

Dumb question of the day: what did the Connie use?

FLYBOYJ · 08-03-2007, 10:26 PM

Quote:

Originally Posted by SoD Stitch

Dumb question of the day: what did the Connie use?

Turbo Coumpounds, 3350s..

HoHun · 08-04-2007, 12:47 PM

Hi Flyboyj,

>The R2800 for the most part was considered a "fighter engine."

Hm, are you sure about that? It seems to have been used in the C-46 and and the B-26, among others.

But I guess I should have had a closer look at the actual power ratings before posting: The R-3350 yielded 2080 HP at optimum altitude at maximum continous power, while the R-2800(-21) provided just 1625 HP, though it was capable of a comparable peak output.

Regards,

Henning (HoHun)

FLYBOYJ · 08-04-2007, 12:53 PM

[quote=HoHun;266782]Hi Flyboyj,

>The R2800 for the most part was considered a "fighter engine."

Hm, are you sure about that? It seems to have been used in the C-46 and and the B-26, among others.[/QUTOE] If you look at its power to weight ratio you'll find many engineers choose it for fighters (and the government also has a say in this decision as well). Although used on multi-engine aircraft, the numbers of single seat fighters who used this engine speak for itself.

Quote:

Originally Posted by HoHun

But I guess I should have had a closer look at the actual power ratings before posting: The R-3350 yielded 2080 HP at optimum altitude at maximum continous power, while the R-2800(-21) provided just 1625 HP, though it was capable of a comparable peak output.

Regards,

Henning (HoHun)

True - also look at fuel consumption at altitude, that has a lot to play in it as well....

HoHun · 08-04-2007, 02:36 PM

Hi Flyboyj,

>True - also look at fuel consumption at altitude, that has a lot to play in it as well....

R-2800-21 at 1625 HP at 26000 ft: 210 gallons per hour

R-3350 at 1630 HP at 26000 ft: 152 gallons per hour

Hm, quite amazing. The R-2800 is not that much more thirsty than the R-3350 if you compare the most economic settings, but it sure gulps the fuel if it's run at high power.

Regards,

Henning (HoHun)

syscom3 · 08-04-2007, 04:11 PM

Quote:

Originally Posted by HoHun

Hi Flyboyj,

>True - also look at fuel consumption at altitude, that has a lot to play in it as well....

R-2800-21 at 1625 HP at 26000 ft: 210 gallons per hour

R-3350 at 1630 HP at 26000 ft: 152 gallons per hour

Hm, quite amazing. The R-2800 is not that much more thirsty than the R-3350 if you compare the most economic settings, but it sure gulps the fuel if it's run at high power.

Regards,

Henning (HoHun)

with a 60 gal/hr difference, multiply that by four, and the fuel consumption for a 4 engined bomber become excessive.

FLYBOYJ · 08-04-2007, 10:27 PM

BINGO!!!!!!!

pasoleati · 08-05-2007, 06:52 AM

Henning, what are your sources for fuel consumption? Is that R-3350 setting perhaps at auto-lean mixture vs. R-2800´s auto rich? BTW, DC-4 and DC-5 didn´t use Turbo-compounds.

HoHun · 08-05-2007, 08:46 AM

Hi Pasoleati,

>Henning, what are your sources for fuel consumption? Is that R-3350 setting perhaps at auto-lean mixture vs. R-2800´s auto rich?

"Airplane Commander Training Manual for the Superfortress", with the scan of the relevant cruise chart found here:

http://www.ww2aircraft.net/forum/avi...tics-8720.html (Mission to Moscow-hypothetics)

For the R-2800-21, it's the P-47 Specific Engine Flight Chart for the R-2800.

If I read the B-29 chart correctly, it's Auto Rich just like the R-2800.

One of the reasons I asked was that the B-29's flight enginner manual had much higher specific fuel consumption figures for the type (or maybe I read the diagram incorrectly), which I found surprising. This manual can be found here:

http://www.ww2aircraft.net/forum/oth...ok-8691-3.html (B-29 Engineering Flight book)

Regards,

Henning (HoHun)

FLYBOYJ · 08-05-2007, 10:21 AM

Quote:

Originally Posted by pasoleati

Henning, what are your sources for fuel consumption? Is that R-3350 setting perhaps at auto-lean mixture vs. R-2800´s auto rich? BTW, DC-4 and DC-5 didn´t use Turbo-compounds.

I actually think he meant DC4 and DC6. The DC4 used R2000s, the 6 used R-2800s. It was the DC7 that used 3350s.