Meanwhile, back on Earth...
I think most ordinary mortals with 'attitude' will fly at speeds similar to
the ones I've quoted.
..and of course, it's not for me to stand in judgement over the performances
which other claim.
One thought though. TAS based on GPS readings is easily over-estimated.
Leaving aside the density/altitude calculations which are frequently aired,
the most common reason is failure to accurately compensate for wind.
It is essential to either:
1/ Fly on a day with zero wind.
2/ Fly DIRECTLY into and away from the wind vector. (pretty difficult to
achieve).
3/ Use a recognised formula to produce TAS from trigonometry.
I suspect that most GPS/TAS calculations which are not performed with
rigourous attention to detail will be over-estimated by a few knots. Arent
simple 'two-way averages' and 'rectangular tracks' are likely to be wrong
unless the weather is calm ?
I have an Excel spreadsheet (4Kb) which relies on averaged GPS speeds from
three, accurately flown tracks. The resulting TAS should be fairly close to
the true airspeed provided:
1/ The aircraft is at constant altitude throughout the test.
2/ The track and GPS speed are fairly constant. (requires a day without
gusts and thermals)
3/ The engine RPM is constant.
4/ The wind direction and speed are constant throughout the test period.
I found that I needed to fly for about 5 minutes per sector, in order for
the GPS reading to average out. I also found it quite hard to hold a track
to within +- 1 degree.
If anyone would like to examine and add constructive criticism of the
method, I'll gladly refine it. I'd like to derive a method that is as fair
and as accurate as possible.
What is the most simple and ACCURATE way to determine TAS ?
Alan
-----Original Message-----
From: owner-europa@post.aviators.net
Subject: Re: Realalistic airspeeds
Au contraire, the performance of Kim's aircraft is indeed relevant for the
rest of us even if it is only as a benchmark.
Although Kim's build philosophy may include a religious attention to detail
he makes no claims to being a deity, and no god-like powers would be needed
to duplicate his accomplishments. It's all a matter of attitude. N111EU
was built light, and incorporates drag reducing modifications beyond the
factory's speed kit, but any mortal builder could duplicate what Kim has
done. His aircraft may be relatively Spartan (emphasis on relatively,
because it is certainly not austere) compared to, for example, Dennis
Vories' XS (whose interior could be compared to a Lexus) but that's
essential to keeping it light. Since the proverbial free lunch still does
not exist, each of us must choose to build light and go fast, or build plush
and sacrifice speed. Just because most builders seem to prefer to have a
little more of the plush stuff that adds weight and decreases speed is no
reason to exclude N111EU as a valid example of the Europa's performance.
Best regards,
Rob Housman
A070
----- Original Message -----
From: "LTS" <lts@avnet.co.uk>
<europa@avnet.co.uk>
Subject: Re: Realalistic airspeeds
> I don't think looking at the performance of Kim Prout's aircraft is
> particularly helpful, unless you're a god. Nobody else seems to have come
> near to the performance acheieved by Kim!!!!! I think this guy wants to
know
> what he can expect to acheive if he buys or builds a regular 914 Europa
Tri
> gear. There are several out there and we have sold props for at least two
> 914 trikes and one 914 mono. I am sure someone can give him typical
actuals.
>
> Jerry
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