Recent content by Kinetics

Thanks for testing and confirming this. Another poster claimed my data was invalid when clearly it is not. The main point is that due to air drag in the environment where the DG-S scrams operate, the scramjets are not worth using. It's more effective to climb to a zero drag altitude then use...

:bananadance::bananadance::hotcool:

We agree that your original statement has been shown to be incorrect and misleading for other readers. However, thanks anyway for your other contribution to the discussion which I read with interest.

:yes::banana:

I interpret the above to suggest we are now in agreement regarding the validity of Nasa's ramjet figures and the finding that "ramdrag increases at a greater rate than thrust". :thumbup:

Rather than obscure or complicate the issue perhaps let's stick to the only point in disagreement : Does ram drag increase at a greater rate than thrust at increasing aircraft speeds? My finding: "Ramdrag increases with aircraft speed at a greater rate than thrust - I provided supporting...

Re: -Well spotted but there was no change in engine inlet area. Example 3 was at 18km altitude; examples 1 and 2 were at ground level. -The relationship of aero-drag to speed is complex. It may not be the square (it's not my area of interest) but it clearly increases at a faster rate than...

Example 1: @ 200kph Gross thrust = 30,949N Ram drag = 1,860N @ 400kph Gross thrust = 32,819N Ram drag = 3,901N - Speed doubled, thrust remained constant and drag doubled. Example 2: @500kph Gross thrust = 34,264 Ram drag = 5,051 @1,000kph Gross...

I downloaded that NASA EngineSim before but never really used it much until today. It's interesting looking at the Ramjet data - shame they don't have scramjets on it. For ramjets, obviously, net thrust is gross thrust less ram drag. The applet shows that ramdrag increases with the...

There are optimum ranges for both speed and density - it's not a simple linear relation. From your claims regarding "speed" and air density you do not appear to have grasped the basic concept of drag being proportional to the square of velocity. In practical terms achieving +Mach 6 in very...

Yes, but they do have some use. Except that you must only allocate them around 150 kg of fuel as they will be on and off pretty quickly if you climb efficiently. But, there is absolutely no point bringing any more fuel than that for the Scramjets as you can only use them if you deliberately...

If you look at the flow rate (and the thrust produced by the Scram) you will see that fuel flow to the DG-S Scram falls from 6kg per second at 20,000m to less than 1kg/sec by 30,000m. This trend continues into higher altitudes.

Sorry but you don't know what you're talking about. If you bothered to check the SCRAM on the DG-S has limits. It cannot go at Mach 17 and it certainly does not have a ceiling of 75km. It barely functions above 30km altitude. Optimum altitude is around 25km. And no I don't mean to say...

re the point about lift by flying at Mach 10 it's not a huge factor

Thanks and this may be obvious to answer but why not just climb to 50km altitude using main engines. It would take only 200 seconds and 1.6 tons of fuel. Consider this hyothetical scenario - over the Pacific at an altitude of 25km located some 8,000 km from the nearest base and carrying...