Jim Wilson wrote:
Yeah, I have been reviewing this, and I think I understand how the definition works. I'm getting pretty much the same numbers based on the 2900 and .35 which I got out of the POH and several internet sources on the cyclone engines. I have a more appropriate yasim file now, but I still can't get it to solve, so I wonder if there is another problem somewhere else? Maybe I have screwed up the aero data and it is producing way too much drag.
Here's the latest: http://home.comcast.net/~jrbabcock/superfort/b29-yasim.2.xml
Everyone, thanks for all the help so far, it is very appreciated, Josh
Not sure if I started with the latest or not, but this one solves: http://www.spiderbark.com/fgfs/b29-yasim.xml
This is what I changed:
1) Added fuselage length.
2) Increased wing length to something closer to correct length. 3) Probably adjusted a couple other less significant numbers that seemed wrong (wing sweep angle maybe?).
4) Fixed rpm/power numbers under the prop tags. They need to be scaled back according to the gear ratio. Someone with a better understanding of mech engineering might be able to explain why the BHP on the prop shaft is reduced by a factor of 0.35 when that's the gear ratio, or maybe that is wrong and there is something going on in the YASim calcs. It seems that is what you have to do to get a solution that works. In any case YASim should at least do some sanity checking here to avoid the endless loop thing.
Solution results: Iterations: 1220 Drag Coefficient: 3.398360 Lift Ratio: 417.065216 Cruise AoA: 1.252508 Tail Incidence: 3.132050 Approach Elevator: 0.268476 CG: -10.439, 0.000, -0.137
This solution isn't quite right. I had to knock down your cruise speed and altitude, but at least you've got something to go back to while tweaking. BTW I don't know much about the B-29, but did you do that airspeed in KIAS? 365 @ 25000 sounds a bit high.
Best regards,
Jim Wilson
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Is the sweep supposed to be the LE or the .25% chord?
Josh
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OK, it solves with this line:
<control-input axis="/controls/engines/engine[3]/propeller-pitch" control="ADVANCE"/>
but not this one:
<control-input axis="/controls/engines/engine[3]/propeller-pitch" control="PROPPITCH"/>
Does ADVANCE mean prop pitch here?
Josh
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