HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old May 10, 2014, 12:43 PM
Ascended Master
Sparky Paul's Avatar
Palmdale, CA
Joined Oct 2000
13,499 Posts
Quote:
Originally Posted by bigtruck169 View Post
this thread is a small summary from all u expertswhat some people think about thermals. thanks for all input
.
ftfy
Sparky Paul is offline Find More Posts by Sparky Paul
Reply With Quote
Sign up now
to remove ads between posts
Old May 10, 2014, 12:44 PM
Ascended Master
Sparky Paul's Avatar
Palmdale, CA
Joined Oct 2000
13,499 Posts
Quote:
Originally Posted by richard hanson View Post
zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz
.
That IS contagiou s ....
Sparky Paul is offline Find More Posts by Sparky Paul
Reply With Quote
Old May 11, 2014, 09:15 AM
Registered User
Zurich
Joined Apr 2006
3,993 Posts
glad to see we are all more-or-less now on the same plain-plane plane

zzzzzzzzzzzzzzzzzzzzzzzzzzzzzz
xlcrlee is offline Find More Posts by xlcrlee
Reply With Quote
Old May 22, 2014, 01:26 PM
Bye Bye VP Aug 2010 - Aug 2012
Gerry__'s Avatar
United Kingdom, London
Joined Jan 2005
6,006 Posts
Quote:
Originally Posted by eflightray View Post
Sorry, haven't really a clue what the thread is about, but I remember someone once posting somewhere that a model travels with the air around it.

Actually it doesn't travel 'with the air', it travels faster than the air, or falls out the sky.

What that has to do with this thread, who knows, but having flown free flight many years ago, I don't think I ever came across air moving in a steady state. There was always some turbulence/thermal/whatever activity, that made trimming a little hit and miss flight to flight.

But with theory I suppose you can discuss anything.
This might help:

http://www.bmfa.org/publications/fil...02FullBook.zip


Quote:
BRIEFING 3 - THE EFFECT OF WIND ON THE AIRCRAFT IN FLIGHT

There is probably more nonsense talked and written on this subject than any other connected with the practical side of flying! In reality, the matter is very simple - it is just that so many people find it hard to accept.

Provided that your flying area is clear of vertical obstructions (houses, trees, hedges, hangers etc.) the wind will blow fairly steadily from a constant direction once the aircraft is above about 50ft. Below this height, and depending on the surface of your flying site and the proximity of obstructions, there will be some turbulence both vertical and lateral.

Once you understand this principle you will see that a turn from an into wind heading to crosswind will appear to be a fairly sharp turn when seen from the ground and a turn from downwind to crosswind will appear to be slow and elongated. You must accept these visual effects for what they are and remember at all times that if you have not altered your throttle setting and the aircraft is at constant height then your airspeed is constant and the aircraft is in no danger of stalling.

Once the aircraft has climbed out of this turbulent level it is, in effect, flying in a steadily-moving block of air. Thus, with a windspeed of 10 mph the block of air in which your aircraft is flying is moving downwind at a speed of 10 mph. So, your aircraft which flies at a speed of, say 20 mph will appear to be doing only 10 mph when flying into the wind (flying speed less windspeed) and 30 mph when flying downwind (flying speed plus windspeed). In point of fact your aircraft knows nothing about the windspeed at all and is flying at a steady 20 mph all the time!

You will often hear people say that their aircraft tends to climb when turning into wind and dive when turning downwind. What is really happening, of course, is that they are subconsciously trying to compensate for the apparent variation in speed and themselves causing the aircraft to climb and dive.

One major point to remember - don’t try to keep your apparent speed constant or you will find that you will have your aircraft at full throttle when going into wind and stalling when it goes downwind.

If you find all this difficult to visualise, try to imagine yourself piloting a model boat from the bank of a fast-flowing river. In this situation you will find that you can understand the problems outlined above.

When flying in a wind of any strength you will find that your model can be carried away from you very quickly when it is travelling downwind. It is essential not to let it go too far. If you do, not only do you stand a good chance of losing control because you just can’t see the aircraft properly, but it is a long and slow slog back to your position against the full strength of the wind. There is another major factor - if your engine stops it will be difficult or impossible to glide the aircraft back to your position if it is too far downwind.

So always try to keep your aircraft upwind of your position as much as possible. By doing so you will save yourself from falling into some very difficult situations.
-- BRITISH MODEL FLYING ASSOCIATION free publication.
Gerry__ is offline Find More Posts by Gerry__
RCG Plus Member
Latest blog entry: Foamie Resurrection
Reply With Quote
Old May 23, 2014, 02:47 PM
Registered User
The Willamette Valley, Oregon
Joined Dec 2008
1,235 Posts
Random:

0) "Briefing 3" posted above is completely on target so far as I can see...

1) 2 weekends ago flying a full-scale a/c within 1000' of hilly terrain there were times while thermalling where I had to straighten out and drive upwind every single time I reached the pointing-upwind leg of my circle, if I wanted to stay centered in the lift. Not terribly surprising considering some previous somewhat similar experiences-- see previous posts. In no way suggests that an aircraft circling in a uniform airmass "feels" the wind in any way.

2) Have you noticed that soaring birds usually point into the wind? I.e. that they spend much more time pointing partly into the wind than pointing partly away from the wind? There is an easy explanation for this that in no way suggests the birds are "feeling" the wind.

3) Wind gradient is hugely important very near the ground. Even when my hang glider is folded up in its long narrow bag on my shoulder, I can make it yaw one way or the other by tilting it so the one end is up high in the faster air and the other end is down low in the slower air. I use this phenomenon to help me control the glider every time I am carrying it folded up in the bag in very strong wind. Similarly, standing with the wing unfolded, no matter whether the nose is pointing into the wind or yawed to one side, if one wingtip is much higher than the other wingtip, the high wingtip will tend to rise, because it is in faster air.

Steve
aeronaut999 is offline Find More Posts by aeronaut999
Last edited by aeronaut999; May 23, 2014 at 02:55 PM.
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion How To Fly In Wind / Forget Gyros, Forget Sims, Fly in Wind Dwayn 3D Flying 4 Mar 06, 2014 07:51 PM
Question Physics in scratch build. Too much moment!!! euro_warfly The Builders Workshop 8 Dec 23, 2013 06:39 PM
Discussion question about KK2-boards Failsafe mode sinking in circles StefanL38 Multirotor Electronics 2 Nov 09, 2013 04:28 PM
Question V tail spinning in circles? boaterguy Scratchbuilt Multirotors 2 Oct 16, 2013 07:56 PM
Discussion Good starter plane, sturdy, steady, and ok in the wind? whaleboy Parkflyers 30 Jul 14, 2008 10:15 AM