Hi Graham.
I agree with your comments about the availability of AOA indications, I
have not looked in depth at this but my understanding is the systems
available are both very expensive and difficult to install.
During development of the Jaguar aircraft the test aircraft had vane
sensors mounted well forward on the pitot boom these measured pitch and yaw
and validated the fuselage mounted incidence gauge. This was a fairly
standard device that had a tube with a pair of slots that rotates to equal
the pressure and aligns with the airflow
On a single engined piston plane anything mounted on the fuselage will be
affected by propwash and other factors, if it is mounted on the wing then
the results will be affected by the wing itself and vortcies and flow
breakdown probably at critical phases of flight. how would you check if the
installation is sound and reports correctly without having carried out
elaborate flight testing first.
I guess and its only a guess is that the pitot based versions are likely to
have the same limitations as standard pitots with things like position
error and other effects I expect these things are all able to be corrected
out one way or another with clever computation. Why is nothing simple ?
I stand by to be corrected
regards
Tim
On 11 May 2014 11:22, GRAHAM SINGLETON <grahamsingleton@btinternet.com>wrot
e:
> Tim
> maybe we are mixing things a bit. ASI will measure instantly changes in
> airspeed.
> When AoA changes aircraft speed will not change instantly but will take
> several seconds.
> The force causing change of airspeed is increase or decrease in drag,
> usually quite a small force.
> During take off acceleration is caused by engine thrust and ASI will
> record speed of course, as soon
> as the aircraft is flying AoA should quickly settle at best climb.
> Stall occurs at the same AoA whatever airspeed or total weight is. (I'm
> thinking aloud here)
> In fact best climb, cruise or glide speeds are also at fixed AoAs. They
> are not at fixed airspeeds but
> change as all up weight changes.
> AoA is much the best primary flight control instrument. That's why fast
> jets use it.
> A pity AoA meters aren't mass produced like ASIs are!
> best regards
> Graham
>
>
> ------------------------------
> *From:* houlihan <houlihan@blueyonder.co.uk>
> *To:* europa-list@matronics.com
> *Sent:* Sunday, 11 May 2014, 8:34
> *Subject:* Europa-List: Re: Europa-List: Re: Europa-List: Re:
> Europa-List: Re: Europa-List: Europa Crash in L=C3=BCbeck/Germany
>
> Hi Graham.
>
> We may be talking apples against pears here BUT if what you say is true
> then on takeoff I would be at 100' thinking about retracting the
> undercarriage before the ASI has moved from zero.
>
> I agree it takes time to accelerate or decelerate a 600kg mass but the
> pressure measurement showing movement relative to the local air mass will
> be indicated within a small fraction of a second even using our normal
> mechanical manometers that are calibrated in airspeed and could be even
> quicker using electronic pressure sensors close to the pitot head.
>
> True an AOA or alpha system would be helpful but I just want to be warned
> if through lack of attention or being distracted I allow my speed to deca
y
> , these lack of attention or distraction events usually build up slowly
> without it being noticed and I would guess rarely happens over one or two
> seconds.
>
> best regards
>
> Tim
>
>
> On 10 May 2014 22:28, GRAHAM SINGLETON <grahamsingleton@btinternet.com>wr
ote:
>
> Tim
> don't think so , the ASI won't move (or shouldn't!) until the aircraft ha
s
> accelerated, or worse slowed down and that takes many seconds.
> When it says "stall speed!" you.ve already stalled. Not a lot of use.
> Graham
>
>
> ------------------------------
> *From:* houlihan <houlihan@blueyonder.co.uk>
> *To:* europa-list@matronics.com
> *Sent:* Saturday, 10 May 2014, 14:31
> *Subject:* Europa-List: Re: Europa-List: Re: Europa-List: Europa Crash in
> L=C3=BCbeck/Germany
>
> Hi Graham.
>
> I think you may have put the decimal point in the wrong place. I
> appreciate what you are suggesting but 20 seconds ?
> I bet the real figure is much less than a second.
> Mind you how would you measure the lag , my ASI seems to move at the spee
d
> of light at times.
>
> Tim
>
>
> On 10 May 2014 13:19, GRAHAM SINGLETON <grahamsingleton@btinternet.com>wr
ote:
>
> Or an AoA meter as primary attitude/speed instrument. The ASI is always 2
0
> seconds too late.
> Very sad, I met Manfred while he was building. A very nice man and a nice
> Europa.
> Graham
>
>
> ------------------------------
> *From:* David Joyce <davidjoyce@doctors.org.uk>
> *To:* europa-list@matronics.com
> *Sent:* Saturday, 10 May 2014, 12:36
> *Subject:* Re: Europa-List: Europa Crash in L=C3=BCbeck/Germany
>
> davidjoyce@doctors.org.uk>
>
>
> I strongly suspect that this another case where a SmartASS or the
> equivalent might have saved them both. David Joyce, G-XSDJ
>
>
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