kaiserbill said:
No problem.
kaiserbill said:
I guess I was simply looking at the physical dimensions of the J-79 vs the RM6 as well as thrust. The J-79 is about 2 meters longer than the RM6, about 10% wider, and almost half a ton heavier, for roughly the same thrust. I think it has a higher airflow requirement too.
The comparison of tab data is not quite right. The Swedes did not consider the engine and the afterburner as a single unit. So if you are looking at tabulated data for the Volvo RM6B or RM6C it does not include the afterburners which were the Ebk 65, 66 and 67. On the other hand US tab data includes the afterburner if the engine model was so fitted.
The RM6C with Ebk 67 (as fitted to the J35D and later models) was 138” (8,140mm) long with a 44” (1,118mm) diameter and weighed in at 3,902 lbs (1,770 kg) dry (no fuel and oil in it). However much of this length (and a bit of the weight) is consumed by a pipe extension to connect the forward mounted engine and the aft mounted afterburner. This engine produced up to 12,456 lbs thrust (max military) or 17,086 lbs (max reheat).
There is no off the shelf J79 that could replace the RM6C + Ebk 67 because of the separation of the engine and afterburner. However the RM6C by itself could be replaced by a CJ805 which was the afterburnerless, civil version of the J79 as used by the fast and cool looking Convair 880 and 990 airliners. This engine could then be integrated with the Swedish afterburner to achieve the improvements I mentioned in my first post (less fuel burn, better throttle response and less cooling).
kaiserbill said:
I would guess that would require a massive redesign to the aft-of-cockpit fuselage internal structure, as well as centre of gravity considerations...etc
Integrating a new engine into the Draken is always going to require some work because it is buried inside the transverse framing of the forward fuselage which is the main structure of the aircraft. It required extensive work just to go from RM6B to RM6C. However the CJ805 is inside the key dimension footprints of the RM6C. And you could convert a J79 with the insert of a pipe between the turbine and the burner that would fit inside the same volume and weight of the RM6C + Ebk 67. Any changes to intake volume could be easily accommodated with the Draken’s fixed nozzle design and the quite large additional airflows brought in for cooling the centre fuselage with the RM6C. The changes would not be massive nor would they have major influence on the CG. As long as you kept to the engine, pipe, burner design.
kaiserbill said:
Hence my pondering wonderment at benefits.
The devil is always in the details.
kaiserbill said:
Thanks for the info on the Swedish defence export issue. Whilst being aware of Palme's odd foreign policies, I wasn't aware of his mentors/predecessors relative real politik.
Sweden went from by-the-book, conservative, neutral but anti-communist to by-the-book, radical and “non-aligned” aligned in its foreign policies.
kaiserbill said:
Not to derail, but a quick question: Do you know what requirement the Lansen was aimed at to compete in South Africa? Was it a strike or intercept role? Trying to figure whether it was aimed at competing against the Mirage III/Sabre/Buccaneer/Canberra, all of which were SAAF projects/purchases in the late 50's/early 60's.
All I know is that the Swedes were disappointed they didn’t sell the Lansen to South Africa. No further details. I can't even remember were I read it (at the moment).