Searching \ for 'Airspeed' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/index.htm?key=airspeed
Search entire site for: 'Airspeed'.

Truncated match.
PICList Thread
'Airspeed'
1999\05\06@202003 by miked

flavicon
face
> have pitot tubes alright, but I'm looking for small ones in the 2-3"
> long range.  I would like to mount it to a model airplane to determine
>
> Does anybody have an alternative idea?
> -----------
> When I was young, I resolved these trouble through heating a NiCr wire
> and measuring how the wire was not so hot when in air flow compared to
> a static heated wire. In fact, some anemometers work this way..
>
Electronics Now had a 'hot wire' anemometer project last year. I
think these would draw to much current for Andy's
application(small ni-cad battery pack).

1999\05\06@212450 by Maris

picon face
I didn't see the Electronics Now project but I've seen this done using a
small pilot bulb with the glass broken off as the sensing element. This
wouldn't use too much current from a Ni-Cad pack.



At 07:18 PM 5/6/99 -0500, you wrote:
{Quote hidden}

1999\05\06@225226 by Herbert Graf

picon face
> I didn't see the Electronics Now project but I've seen this done using a
> small pilot bulb with the glass broken off as the sensing element. This
> wouldn't use too much current from a Ni-Cad pack.

   That sounds like a good idea. AFAIK the EN article used a solid state
device self heating characteristic to determine airspeed. I think it used
two transisters, one as a control device and one as a sensor. I remember
reading it, was interested in making it until I found out that calibration
wasn't that easy, it involved traveling in a car on a windless day, just
couldn't be bothered with that. I can look it up if someone is interested.
TTYL

1999\05\07@030442 by Mark Willis

flavicon
face
Herbert Graf wrote:
>
> > I didn't see the Electronics Now project but I've seen this done using a
> > small pilot bulb with the glass broken off as the sensing element. This
> > wouldn't use too much current from a Ni-Cad pack.
>
>     That sounds like a good idea. AFAIK the EN article used a solid state
> device self heating characteristic to determine airspeed. I think it used
> two transisters, one as a control device and one as a sensor. I remember
> reading it, was interested in making it until I found out that calibration
> wasn't that easy, it involved traveling in a car on a windless day, just
> couldn't be bothered with that. I can look it up if someone is interested.
> TTYL

 I've been thinking about calibration;  Borrow time at a campus wind
tunnel, for higher speeds?  (Borrow a friend with an airplane?  <G>)

 For slower speeds, you should be able to swing the unit on the end of
a rod, inside, at certain rotational speeds & get some good slow speed
calibration information.  (Want faster?  Attach a 1/2 Hp big power drill
to the center point <G>)

 You need to measure the RADIUS, and rotational speed, from that figure
out the tip speed.

 For example, 8' (wood 1"x2"?), 2Hz rotation rate, you get a rough
speed at the tip of the rod of:

 Pi = 3.14159 etc <G>
 r  = 4' here (I assume you pivot the rod at it's center)
 T = 0.5 sec (= 1/(2 Hz))
 V = Velocity = 2*Pi * r / T = 50.26 Ft/S, * 5280/3600 = 34.27 MPH

 (Don't forget that you're talking some radial accelerations here -
don't tangle with that rod - Don't overdo the G forces here, and so on.
Shorter rod at lots faster RPMs gives higher speed capability with less
G forces <G>)  Good idea to balance that rod, too.  I'd sure put my PIC
& electronics near the center.  Could swing 6" and counterweight the
short end, too.

 Mark

1999\05\07@200358 by Roland Andrag

flavicon
face
>  I've been thinking about calibration;  Borrow time at a campus wind
>tunnel, for higher speeds?  (Borrow a friend with an airplane?  <G>)


What happened to the car window? Or get up on the back of a truck.. Assuming
you can hold the plane, that is... Take off the wings - use only the
fuselage...

Cheers

Roland

1999\05\07@211927 by Russell McMahon

picon face
You could turn the sense and reference wires on only occasionally to
reduce current drain.
Heating time of a small wire is near instantaneous.

>Electronics Now had a 'hot wire' anemometer project last year. I
>think these would draw to much current for Andy's
>application(small ni-cad battery pack).

1999\05\07@212324 by Sean Breheny

face picon face
Could be a problem if you have vigilant police :) Those model jets can
reach >100 mph easily.

Sean

At 05:50 PM 5/7/99 +0200, you wrote:
>
>What happened to the car window? Or get up on the back of a truck.. Assuming
>you can hold the plane, that is... Take off the wings - use only the
>fuselage...
>
>Cheers
>
>Roland
>
|
| Sean Breheny
| Amateur Radio Callsign: KA3YXM
| Electrical Engineering Student
\--------------=----------------
Save lives, please look at http://www.all.org
Personal page: http://www.people.cornell.edu/pages/shb7
spam_OUTshb7TakeThisOuTspamcornell.edu ICQ #: 3329174

1999\05\07@213204 by Andy Kunz

flavicon
face
At 09:21 PM 5/7/99 -0400, you wrote:
>Could be a problem if you have vigilant police :) Those model jets can
>reach >100 mph easily.

The ones I'm working with do 110 mph at 70% throttle.

And that's an electric!

Andy

==================================================================
  Montana Design Tech Support - http://www.montanadesign.com
==================================================================

1999\05\07@213215 by Steve

picon face
-----Original Message-----
>  I've been thinking about calibration;  Borrow time at a campus wind
>tunnel, for higher speeds?  (Borrow a friend with an airplane?  <G>)


As a new private pilot, I volunteer the plane if it's in the Baltimore / DC
area!  Is 100kts fast enough?

-Steve

1999\05\08@002752 by Mark Willis

flavicon
face
Roland Andrag wrote:
> <snipped>
> >  I've been thinking about calibration;  Borrow time at a campus wind
> >tunnel, for higher speeds?  (Borrow a friend with an airplane?  <G>)
> > What happened to the car window? Or get up on the back of a truck.. Assuming
> you can hold the plane, that is... Take off the wings - use only the
> fuselage...
>
> Cheers
>
> Roland

 Andy mentioned that it's a model JET aircraft.  IIRC some of those,
years ago, used to really move rather quickly (something like 200+
MPH.)  I don't want to be in the back of a pickup, doing 200 MPH,
relative to wind OR ground <G>

 Mark

1999\05\09@204303 by Des Bromilow

flavicon
face
what's wrong with making some kind of "multipier" to scale up the speed.
I'm thinking something along the lines of a funnel of know crossectional area which tapers down to a tube of known smaller crossectional area. Hoping that compressibilty is somewhat neglibile (or calcuable<is this a word?>) then the car could could be doing 50, and the air in the narrow portion of the tunnel doing 100, or 200.
Obviously such a device would need to be mounted, but could be easily made and used.

My two cents,
Des

>>> Mark Willis <.....mwillisKILLspamspam@spam@NWLINK.COM> 5/8/99 2:26:57 pm >>>
Roland Andrag wrote:
{Quote hidden}

 Andy mentioned that it's a model JET aircraft.  IIRC some of those,
years ago, used to really move rather quickly (something like 200+
MPH.)  I don't want to be in the back of a pickup, doing 200 MPH,
relative to wind OR ground <G>

 Mark

More... (looser matching)
- Last day of these posts
- In 1999 , 2000 only
- Today
- New search...