enginehistory.org

jjuutinen · Joined: 13 Jul 2003 Posts: 180

The data card for the P-47D-30 gives the combat rating as 2535 hp at 64"/2700 rpm and highest dry rating as 2000 hp/52"/2700 rpm. Both are 5 minute ratings. For the P-47M, combat rating is 2800 hp/72"/2800 rpm and the highest dry (take-off) is 2100 hp/53"/2800 rpm. In a Flight journal article a pilot remembers that his chief modified his P-47D to give 90".

kmccutcheon · Posted: Mon Oct 03, 2005 05:28 Post subject:

jjuutinen · Joined: 13 Jul 2003 Posts: 180

These ratings are valid from sea level to about 27,000 ft. The upper limit is based on turbine rpm.

kmccutcheon · Posted: Sun Oct 09, 2005 07:06 Post subject:

jjuutinen:
Summary:
1) You seek data comparing the dry rating of an engine running grade 100/130 fuel to its wet rating running grade 91/96 fuel.
2) Since little such data has emerged, an alternative is to predict the behavior of dry/wet 91/96 fuel using data from other fuels used in engines for which the dry/wet ratings under nearly identical conditions are published. This allows comparison of power increase based almost entirely on the use ADI. An ideal comparison would show the dry and wet ratings of an engine at the same altitude, outside air temperature, and RPM, with the only variable being the increased manifold pressure allowed by ADI. Take off ratings, which come close to this ideal, formed the basis for the table I provided comparing 14 different engines.
3) Two trends appeared in the data I provided:
a) In no case was the power increase from ADI greater than about 17%;
b) The percentage of increase was very highly dependant on the make and model of engine.
4) You provided data showing two cases of power increases due to ADI of greater than 17%. These were both installations with turbosuperchargers and intercoolers, indicating that the percentage increase is also highly installation dependant.

Conclusion:
For a given installation, if one has both the dry and wet ratings for grade 100/130 fuel, it may be possible to predict the wet rating of 91/96 from its published dry rating. It is not possible to predict the power increase due to ADI for grade 91/96 fuel for the general case.
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Kimble D. McCutcheon