Interview – Pete Conrad

PC: Well we probably started as early as anybody did on the propfan development early engineering work and study has been going on at McDonnell Douglas for five years now. It appears to me that the MD-80 line is probably going to be running into the 1990s and with the MD- 89 being about a 160-passenger plane with the propfan coming along at the 100-passenger size. Actually, the propfan would most probably surpass the MD-87.

JT: So you think the MD-87 might be phased out of production after a year in favour of a propfan design?

PC: Well I’m not sure that will happen because one of the unique things about the MD-87 is its tremendous range and in the United States, and I am sure in other places, you are going to get more and more city pairs that are low traffic but they are fairly far apart. People would like to connect say Pittsburg, Pennsylvania with Portland, Oregon on a non-stop, there is not a lot of traffic there but there is some. So the MD-87 fits in very well in that role, because the MD-87 has another feature which is that it has extremely good short field capability, so it can operate in and out of very small fields and it can still go very well on range.

JT: Can you tell us a little more about the successor to the DC-10, the MD-11, and what it means to the long-term aspirations of McDonnell Douglas in the heavy airliner market?

PC: Well you have currently the 747- 300 stretched upper deck and Boeing has recently launched the 747-400. Those airplanes are in the 450 passenger category and even though the long range twin is going to come along with a very great range capability you still have a very definite gap, size wise between the 250 passenger long range twin and a long range 7 4 7 and the MD-11 fits in there nicely at about 330 passengers. We think that the economics of the airplane on a seat mile basis are excellent. They are very very good, we think that there is a gap in the market where we could sell enough MD-11’s to make it worthwhile to produce that airplane and we are looking at using relaxed stability dynamics with the tail carrying fuel though we are not looking at fly-by-wire but we are looking at a cockpit that is completely up to todays standard ARING 700 type cockpit.

JT: Changing to the military environment; your F-15 Eagle has grown in capability extensively over the years, do you see a similar potential growth in the basic F-18 design?

PC: Yes, I think so. The Navy is very pleased with the airplane. If you get out to the operational forces they tell you it does an amazingly good job and has the best trap rate aboard the carrier because it is such a stable airplane coming aboard the ship. With the bomb aiming system on it, people are bringing in much better CEP’s than they did with the older A-7s and F-4s and one of the things that we are currently looking at right now is more fuel. Everybody always wants more fuel, so we are looking at that and we are also looking at a better night and all-weather capability. That is currently at the request of the Navy so I think that the F-18 will grow both in its endurance and range capability and of course if you do that you can look at it the other way or have an even better load-carrying capability at the same range it has today. If you do that I believe the airplane is going to grow and of course it has a substantially more modern cockpit than the F-15 does.

JT: How is McDonnell Douglas coping with the latest airframe fatigue problems associated with the F-18?

PC: Well the problem that came up with the F-18 is really straightforward. Nobody is smart enough to design anything perfectly and it’s obviously why we have fatigue test articles. The fact of the matter is that the guaranteed structural life of the airplane is 6,000 hours and what most people don’t realise is how you achieve the 6,000 fatigue test hours. How do you say this airplane is going to be good for 6,000 hours and frankly even in todays modern environment we aren’t that expert on the actual analysis on structures and what you are trying to do is make the strongest structure with the lightest weight to keep performance up.

So what happened in this particular case was, our fatigue test article failed at 10,800 hours at this particular point in the bulkhead which is exactly why we have the fatigue test article to find out if we have made a mistake. As it is not an exact science what we really have to do is a structural life of 12,000 hours because the arbitrary figures say we are not that smart so we divide whatever we get by two.

Theoretically, the bulkhead might fail at 5,400 hours which is 600 hours short of the guaranteed service life. The actual problem interestingly enough was a very old one in that we had a radius in the machining of the bulkhead at this particular point where the radius was too sharp and that gives you what is known as a stress concentration and that’s where it cracked and the nice thing is the way you fix something like that. You simply make the radius larger so in this case we are going to take some more metal out of the bulkhead by making the radius a little bit larger and that will relieve the stress concentration and we will then proof it to the 12,000 hours to make the guarantee of 6,000.

Furthermore the way contracts are being written today we assume any additional cost. There is no additional cost to the government for the airplane because it was part of our original agreement that we will fix anything that happens. Well this happened to be the world cheapest fix for both the airplanes that are in service and the aeroplanes that are coming down the production line.

But let me point out something else about the F-18. This fatigue testing takes a long time, you have to physically cycle the aircraft through each mission, apply the loads and measure the G’s, etc, it all takes a lot of time to log the thousands of test hours that we need. Obviously, while this is happening airplanes are already flying well before the tests are complete. This is why situations like this occur well after the programme has been launched and the first units of the aircraft are operational.

The other problem, with the tailfins, was a little different. Back in the seventies we had with the Navy come up with a set of specifications to design the structure of the airplane and in doing that you have to accurately define the flight environment the airplane is going to fly in. What happened was that when it entered service the USMC and USN pilots found that they were able to perform manoeuvers that they had previously thought impossible with the aircraft. Basically the aircraft was much more agile than anticipated, or originally hoped for and naturally any worthwhile fighter jock will exploit this advantage to the utmost to stay ahead of the competition. The result was that we then had airflow and stress problems placed on the tailfin area that caused the cracking that was reported a year or so ago. This has also been a relatively simple fix and all mods have been done at our expense even though it wasn’t really a fault of the basic design.

JT: How confident is McDonnell Douglas of selling a version of the AV-8B Harrier II to the USAF for their close air support role?

PC: I really don’t know the answer to that question but one of the things that is going on at the same time that we are looking at an enhanced night capability for the F-18, is a parallel program for the AV-8B Harrier II for the Marine Corp to give it a better night and all-weather capability.

When that comes through you are going to have an extremely versatile airplane, and I am sure you are aware that the AV-8B will carry twice the payload that the AV-8A will and I think that the Marine Corp is particularly pleased with its closer support role. As for the Air Force, their programme is only in its infancy so it is hard to see where the outcome will be. We are in there trying though.

JT: The F-15 Eagle has over the past year or so become a test bed for several new aerodynamic developments including thrust vectoring and enhanced STOL performance through the use of canards. Do you see any of these new developments being incorporated in future versions of either the F-15 or F-18 aircraft?

PC: I don’t think so because most of the thrust of doing this test work has been financed with the view to the ATF (Advanced Tactical Fighter) and you may be aware that the Air Force has now let the first set of specifications out to the contractors to look at for ATF and most all of the contractors, General Dynamics with the F-16 or ourselves with the F-15 have been using those aeroplanes to look at concepts I think would be really built in to the ATF.

JT: McDonnell Douglas purchased Hughes Helicopters in 1984 and dropped the latter name only recently in favour of a higher corporate profile in the rotary wing field. What are the broad plans of McDonald Douglas in developing a future generation of civil and military helicopters?

PC: Well we are very interested in that end of the business and one of the things that people may not be aware of in the purchase is that the facilities at Culver City did not go along with the sale. One of the other things we have done is to consolidate the whole effort at Mesa Arizona where the AH-64 is being manufactured now, so we are investing in an additional large amount of money in coming up with a new engineering campus over there and we have obviously great involvement now in the LHX programme which will be the next really large helicopter purchase by the US Army and we are pulling this new facility together with the idea in mind of having the most advanced helicopter engineering group that we can assemble to work on LHX.

But we will also be looking at some other helicopters namely another new light helicopter to ultimately replace the 500 series and the Army recently increased its requirement for AH-64s. I am not sure of the number but I think they have now stated that they are going to want over 1200 of them. The initial order was for just over 600 and something and we have now delivered maybe only 70 AH-64’s off the production line. So that’s a long production line that is going to help McDonnell Douglas in investing heavily in the future of the helicopter business.