ParlInfo - Parliamentary Joint Committee on Foreign Affairs, Defence and Trade : 20/03/2012 : Department of Defence annual report 2010-11
Mr Burbage: Weight is most critical on the short take-off, vertical-landing jet. That is the one that has the toughest requirement for taking off from and landing on small ships. You saw in the movie that we did that, this year. We predict the weight on that airplane to grow at about three per cent throughout the rest of the test program and it could grow some more throughout its life if more capability that has substantial weight goes on the airplane. (per year shoudn't have been said as it conflicts with facts)
If you look at the STOVL jet and you look at our weight charts, which you are more than welcome to see, we have now gone two years without any weight increase on the STOVL jet, and that is while accommodating engineering changes to the doors, which we have replaced with heavier doors, and other changes that were made to the airplane. (
Dr JENSEN: I will show you the chart. I am afraid it is a bit small, but you can see there is January 2010 and there is January 2012. Clearly there has been a weight increase.
Mr Burbage: This increase right here is a ground rule change, not unlike other ground rule changes—when the weight of the electro-optical targeting system was added in, it is just a step function increase. If I bring this down and I measure that point directly back, it goes back two years to intercept that curve there.)
We manage the weight very tightly on that airplane—for good reasons, because it needs to be.
The other two airplanes are not as sensitive to weight. We are actually probably several thousand pounds away from the first compromise of the performance requirements of those two airplanes. We do, however, manage the weight very tightly on all three airplanes. The metric that we look at is when the weight growth curve levels off, that means your design has stabilised. You are no longer making lots of changes to the design. All three airplanes are now in that level-off phase. The best one is the STOVL where you can go back and see that we have not increased any weight at all in a full two years.
Senator FAWCETT: So having reached that steady state, you are saying you are some thousands of pounds away from—
Mr Burbage: On the non-STOVL jets.
Senator FAWCETT: So the conventional take-off and landing—
Mr Burbage:
The key performance requirements that are weight-dependent have large margins still ahead of them. On the STOVL the key performance parameters are much tighter to the weight, because it is more physics than aerodynamics.
Mr Burbage: We have 16 key performance parameters on this airplane. Half are logistics and sustainment-related, half are aeroperformance-related and one or two are in classified areas. We have an oversight body called the Joint Requirements Oversight Council, the JROC, that looks at those requirements every year and makes decisions on them—'Are we going to meet them, are we not going to meet them? If we are not going to meet them, what is the impact of that?' We have one this year which was the range of the Air Force airplane which had a specific set of ground rules associated with how that range is calculated which is not similar to either of the other two airplanes. The airplane flies a large part of its mission at a non-optimised altitude in the original calculation. The JROC agreed to change the ground rules to fly that airplane as the other two were flown and, when that happened, the airplane had excess margin to the range requirement. For any performance-related requirements, we artificially penalise the engine by five per cent fuel flow and two per cent thrust. Those margins are given back as we mature the design and get more and more solid on exactly what it is going to do. They are there for conservative estimation up front. We have not taken back any of those margins yet so, when those margins are taken back, the airplane will continue to be well in excess of its basic requirement. The airplane is meeting all of the other requirements today.
Mr Burbage: To the original set. Today, all the KPPs are green because that ground rule was changed to be common across all three airplanes on the range. But we have not taken back the margins that are being withheld to make sure those performance predictions are conservative. We are not going to have degraded engines. We basically measure our performance characteristics with a highly-degraded engine capability. Our actual flight test information coming back from the engine is better than nominal. These calculations are not done using actual airplane test data. They are done using an artificial penalty that gets paid back as the design matures.
LO. think again what SL 750kn means with internal fuel and weapons and what other planes are, as to what you are saying. your mighty su.35 is 755kn clean