So how accurate do you think your Anemometer is?

[Dave M]

Just a thought, as the weather is playing its games, how accurate do you think your wind meter (anemometer?) is.

 

I have recently bought a cheap meter from the far east, £12 ish deliverered which seemed worth a try. The first time I tried it, it gave a reading of 37mph average, with 51 mph gusts, one of the other lads measured at the same time and came up with 17mph and tried to convince me this was right and that I need to get my meter calibrated! I later checked and my reading was pretty close to the hourly observations on the met office site, also, you could really feel the wind pushing you back!

 

Today I did a scientific test. Driving along at consistant speeds, holding the meter out of the window and comparing the meter reading with the speedo, also comparing again with the met office data, my meter did seem to be pretty accurate. The instruction leaflet suggest that it has a 5% margin of error by the way.

 

(The test was completed on a private road and with a helper holding the meter while I drove and read the speedo for you safety guru's out there).

 

So, how much do you need to pay to guarentee accuracy and do you trust your anemometer?

[Devon Flyer]

Posted by Dave M on 15/12/2011 16:33:24:

So, how much do you need to pay to guarentee accuracy and do you trust your anemometer?

 

Too much and no, would be the short answers.

Gave up using an anemometer, as a flying gauge, some time ago. Only ever use one now out of interest and even then I get conflicting readings. A lot depends whereabouts on the slope you take the reading.

Best gauge is to lob one off the slope and watch it fly..............or sink..........as the case may be.

[Dave M]

I think your right, as you may remember from the day at morthoe, I decided to not to fly because I thought it was too much for me on the day, having not previously flown the site before and not being confident of the landing area. That had nothing to do with the meter reading, rather based on what I felt on the day.

 

The sunday was better, until I bounced the WT!!

 

 

Still, its all fixed and waiting for the weather, maybe this weekend looks good?

 

[Erfolg]

It is a pity that contributors feel the need to outline there approach to safety, as a matter of course, to avoid the odium of the safety warriors.

 

 

I have considered purchasing a meter myself, as suggested, for comparative curiosity.

 

Edited By Erfolg on 15/12/2011 19:05:58

[Wingman]

Whenever I've used my anemometer (handheld cup variety) the ancient wizened wet finger brigade always reckon that the windspeed is nearly double what it actually is.

Edited By Wingman on 15/12/2011 19:12:33

[Devon Flyer]

Posted by Wingman on 15/12/2011 19:11:56:

Whenever I've used my anemometer (handheld cup variety) the ancient wizened wet finger brigade always reckon that the windspeed is nearly double what it actually is.

Edited By Wingman on 15/12/2011 19:12:33

 

I bet the planes flew exactly the same, whichever method was used to measure the windspeed.

[Andy Gates]

I got one a few christmasses ago to give an idea of the wind speed, gusts and turbulence.

Mine is the turbine in a tunnel type, very small and handy.

 

I have never really needed to check the accuracy as I only wanted a guide.

Seems to give me the data I want.

 

I can't recommend the accuracy of holding the meter out of a window of a car going along since the airflow around the car is quite disturbed and runs faster around the car than the actual speed of the car.

Only direct comparrison against a calibrated instrument would confirm the accuracy.

[Biggles' Elder Brother - Moderator]

Well, as you ask very accurate indeed!

 

We use these in our wind tunnels. They are accurate to about 1 part in 10^4 so for a 25m/s flow speed they are accurate to about +- 0.0025m/s.

 

And the answer too your second question is.... very expensive indeed. A one component system (used in the tunnel upstream of the model) comes in at about £45k. The two component systems, which we use for probing flows around models, are about £120-250k depending on what extras you buy with them.

 

They are very accurate though - but a little hard to transport to the field

 

BEB

[Dave M]

Crikey BEB, surely its not the size that counts! .

 

Andy, I know I said it was scientific, but.....................maybe not that scientific,.I suppose I wonder, as there does seem to be a bit of "pride" (or bravado) on some forums etc about the wind speeds people fly in, as Wingman suggests in his post , there can be some wild guesswork!

 

I think that this is one of the big changes you need to get over when starting slope flying, actually wanting the wind, and actually launching into it, rather than not wanting too much when power flying, that and landing of course .

 

DM

 

[Dave M]

Sorry, double post for some reason.

Edited By Dave M on 16/12/2011 08:05:28

[Del Wheatley]

I do quite a lot of shooting some of it on long range targets,We arn't allowed wind speed measuring equipment so have to spend a long time learning to gauge wind speed by it's effect on the surroundings so we can adjust aim to get the POI of the bullet in the right place.

[Olly P]

Del - Same, out to around 1000 meters. what do you shoot?

[Ben B]

I've also got a cheapy anenometer and although I do sometimes use it, it doesn't give me much information in spring/summer/autumn above and beyond just looking at the movement of leaves on trees etc. In winter there aren't any leaves and the trees therefore move less so I tend to use the anenometer a little more as I'm aware that my ability to judge wind in winter is not good (the other day I estimated 15mph but my plane flying backwards told me otherwise!). However, it's still possible to drop a few blades of grass and see how far away they land, tried, tested and reliable (unless platform shoes come back into fashion on the flying field in keeping with the whole "retro" movement).

 

My only concern about the cheapy anenometers is that they don't come with cases and if gunk and debris builds up between the fan and the spindle it will introduce drag which will massively effect the thing.

[Biggles' Elder Brother - Moderator]

One of the issues I find is that while I think I can estimate wind speed at ground level fairly accurately - I use the system Ben mentions, a few blades of grass tossed aside! - it can be completely different 100 feet up out of the relative shelter of the trees etc. You think "Ah its not so bad" then off you go and turning 'into wind' on the completion of the first circuit the model proceeds along with its tail stuck out at 45 degrees! Mmmm, maybe the wind direction and speed are a bit different up there...

 

BEB

[Del Wheatley]

Posted by Olly P on 16/12/2011 08:45:51:

Del - Same, out to around 1000 meters. what do you shoot?

 

In the gun cabinet at the moment

 

Berreta 686s

 

Theoben Evolution .22 (gas ram)

 

Bsa Scorpion se .22 (pcp)

 

Browning .243 x bolt (my favorite)

 

I do quite a lot of pest control for the surrounding farms and as my house is surrounded by the crop fields my practice time and space is unlimited realy.

That also means plenty of flying space too once i've learnt how.

[Olly P]

Lucky.

 

I tend to shoot L85A2, G36K and recently had a go with an MP7....

 

And I get paid for doing it and ammo provided...not too bad really...

[Del Wheatley]

We get paid sort of but it's more the batta system.For looking after the land,the pheasant pens and dealing with poachers we get use of all the land(some 100,000 acres.it's like a big playground once the crops are done),we help ourselves to the root veg when it's harvested,fishing in the private lakes and a bit of free diesel from the farms tanks.

[Former Member]

[This posting has been removed]

[Olly P]

LOL nice Eric - Targets will scream swear, bleed and then fall over when hit

[Del Wheatley]

it's mostly rabbit,pigeon,pheasant and the odd roe deer but only if it's sick or badly injured and we can't help it any other way.

I won't shoot the foxes but have found they can be kept off the pheasant pens by baiting them away with free rabbit dinners.

i've got a clay trap and a couple of knock overs for practice.

i've been favouring the air rifles a bit recently,cheaper to use and more challenging to get the job done.

[Olly P]

Fair enough - Quiet too. I had an old spring load type air rifle when I was a lad and used to hunt Dinner on occaision, a nice bit of Rabbit.

 

My shooting now is done mostly at competitions and when the targets can shoot back, so has a slightly different slant...