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Re: Jim Drew of XPS

PostPosted: Wed Feb 23, 2011 11:02 pm
by RCModelReviews
A dynajet won't get you 100 miles -- at those sizes, pulsejets just don't have the necessary efficiency (TSFC) to deliver that kind of range -- the fuel payload would be too great. At 100mph it would take 60 minutes to travel 100 miles and that would involve carrying about 12lbs of fuel -- plus airframe, plus engine, plus control system (so we're talking at least 16-18lbs). No model of that weight will hit 100mph in level flight with just 4.5lbs of thrust -- in fact it'll have a hard time flying at all straight out of the launch.

Quite a few people have been flying XPS without issues -- but in those early days of magical antennas, no frequency agility etc -- lots of other people lost models to it, that is without question.

JD may have some clever people working for him -- and that's got to be a very good thing -- since he has demonstrated on numerous occasions that he has little clue when it comes to even the most basics of electronic/electrical theory. His public display of ignorance of Ohms Law was perhaps the most outstanding example of this.

Still -- XPS seems to work okay now so it's all good.

Re: Jim Drew of XPS

PostPosted: Thu Feb 24, 2011 4:15 am
by Engineer
You are underestimating the engineering expertise of the Boeing C. It was a Dynajet but it was highly modified. I don't remember the details because it was 40 years ago.
I do remember that we exceeded 100 MPH by a wide margin.