On Friday 16 June 2006 06:32 am, Maria Vega Ramirez wrote:
> So, if the engine´s delay is 5seconds, how can I know the bypassratio
> number for this spool-up time?Is there any law about this?
Oops, I spoke to soon. The formula for delay in my previous email is correct,
but there is more to do.
The value known in the code as "delay" is actually the engine acceleration in
units of N2 per second. The spool-up time from idle to 100% will depend on
where you have set your idle N2. If we assume you set an idle N2 of 30%,
then the range from idle to max rpm is 70 "N2 units". If you want the engine
to take 5 seconds to traverse these 70 N2 units, then you need a "delay"
value of 14. In other words, you want the engine to accelerate at 14% per
second.
So, to avoid confusion, we'll call your 5 seconds the "delay", and we'll call
the 14%/sec the "accel". If your idle N2 is set at 30%, then you have an N2
range of 70. The relationship between "delay" and "accel" is:
accel = 70 / delay
Now we can use the formula: bypassratio = ( 60 / accel ) - 3
So, using the assumptions above, your bypass ratio should be 1.28
Please let me know if this works for you, so I'll know if I'm just confusing
myself.
Dave
_______________________________________________
Flightgear-users mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/flightgear-users
