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yuuppers
01-12-2010, 09:38 AM
Any info on how the bomb load effected range?

WhiteKnight77
01-12-2010, 11:21 AM
More weight decreases range. The XX Air Force had problems with planes running out of fuel flying from Siapan, Tinian and Guam. Reducing the bomb load helped extend the range along with some other changes like flying at a lower altitude (not flying into a head wind such as the jet stream helps too).

JtD
01-12-2010, 12:58 PM
The effects are not that large if you do not have to reduce the fuel load in order to carry the extra bombs. IIrc, the B-17 manuals gave weight dependent ranges in 5000lbs increments, so basically, there are cases where it would not matter if you took off with 5000 lbs extra bombs. On the paper. Maybe someone has the pages ready.

A rough estimate would be 10% extra weight to equal about 10% extra power at cruising speed, meaning about 10% less range but then there are many variables.

horseback
01-12-2010, 01:22 PM
There are a number of different tradeoffs, depending upon the aircraft; a heavier internal load might only affect climb, but if your bomb bay was also the location of your extra fuel cells, a greater sacrifice of range might be traded for a bigger punch.

Some aircraft included the option of loading bombs externally, and depending upon the type and number of external stores, the drag could be an issue as well. A lot of prewar designs had internal bomb bays that could not hold what wartime experience proved to be a 'useful' load.

In short, there were few absolutes.

cheers

horseback

Bremspropeller
01-12-2010, 01:47 PM
- longer take-off runs (may lead to limitations)
- lower climb-rate
- higher power-setting during climb or considerably longer time to altitude (both give fuel penalies)
- higher drag in cruise
- higher altitudes may not be accessible

jarink
01-12-2010, 02:20 PM
As a general rule of thumb, the more bombs carried, the shorter the range.

B-17s and B-24s could use extra fuel tanks that were installed in a portion of the bomb bay. Doing so obviously reduced the amount of bombs carried.

I have a range chart for the B-17 at home. I'll post it later.

yuuppers
01-12-2010, 04:34 PM
Originally posted by jarink:
I have a range chart for the B-17 at home. I'll post it later.

Thanks jarink, that is the kind of info I am looking for. http://forums.ubi.com/images/smilies/25.gif

jarink
01-12-2010, 05:43 PM
Here's a PDF document from the B-17F Pilot's Manual. It's 29 pages with lots of charts showing fuel consumption, ranges, etc. under different conditions.

B-17F ranges (http://sites.google.com/site/jimrinkenberger/B-17Ranges.pdf?attredirects=0&d=1)

yuuppers
01-12-2010, 05:50 PM
Originally posted by jarink:
Here's a PDF document from the B-17F Pilot's Manual. It's 29 pages with lots of charts showing fuel consumption, ranges, etc. under different conditions.

B-17F ranges (http://sites.google.com/site/jimrinkenberger/B-17Ranges.pdf?attredirects=0&d=1)
Great stuff, very much appreciated. http://forums.ubi.com/images/smilies/25.gif http://forums.ubi.com/images/smilies/25.gif

JtD
01-12-2010, 10:16 PM
Originally posted by jarink:
Here's a PDF document from the B-17F Pilot's Manual. It's 29 pages with lots of charts showing fuel consumption, ranges, etc. under different conditions.

B-17F ranges (http://sites.google.com/site/jimrinkenberger/B-17Ranges.pdf?attredirects=0&d=1)

Very nice, thank you!

JtD
01-13-2010, 09:02 AM
Looking through it, I think that's the one I had a look into before. If you check out the range tables, which exist in 5000 lbs aircraft weight steps, you can see that the ranges on the same fuel load vary about 5%-10% for each 5000 lbs step.

It's not that much, but obviously if you have to take external loads or reduce the fuel load in order to ship extra bombs, the range is going to decrease dramatically.

Thanks again jarink!