Earlier this month, Rolls Royce Turbomeca installed and demonstrated the performance of the Adour MK 821 turbofan engine on a Royal Air Force Jaguar at the RAF Station, DCAE Cosford. This was a ground-test. The Air Attache of the Indian High Commission in London was invited to witness the demonstration. Rolls Royce is pitching the MK 821 as a natural evoluation from the MK 811 that currently powers the IAF Jaguar. The company is also pitching from the angle that the new engine has a high degree of commonality with the Adour MK 871 which powers the Hawk trainer now in use with the IAF.Two Jaguar pilots I spoke to say it seems natural for the aircraft to be souped up with new engines of the same make, since integration and maintenance would be made more seamless that way. However, American firm Honeywell, which has pitched the F125IN turbofan for the competition says integration will not be a problem, and that the upgrade will be possible with no modifications to the airframe. Sources also say the weight of the F125IN goes in its favour against competition. The engine was demonstrated to the IAF in 2007. An official who was present for the demonstration says the American engine has far superior tolerance to debris damage and bird hits than the Adour MK 821.