Design for Windy conditions (Full Version)

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subtleguru -> Design for Windy conditions (4/23/2008 10:16:52 PM)

Sometimes while one model can handle 15mph cross winds comfortably others are battered around the sky and really difficult to land. So the question is what are the characteristics that influence how well a model reacts to windy and gusty conditions.

Some possibilities

1. Wind loading ?
2. High cruise speed (relative to gust strength)
3. Large effective rudder
4. Size ?
5. Low drag

Is wind loading relevant or does is just influence cruise speed ? Likewise for size.

Needless to say I am talking about powered flight and not slope or dynamic soaring.




crasherboy -> RE: Design for Windy conditions (4/23/2008 11:41:50 PM)

Wing loading ,maybe some effect, but in my opinion the design of the craft would be more inportant,like a shoulder or low wing with not to much dihedral. To much rudder[fin] would not help you in better handling,in my humble opinion. A high wing ,light wing loading ,a lot of dihedral like in a trainer ,more fin and rudder area than needed for good control ,would, it seems to me would be the worse in crosswinds. Maybe others here have some ideas on this subject. O yes ,a lot of fuselage side area would make it more prone to being blown around.



HighPlains -> RE: Design for Windy conditions (4/24/2008 12:27:31 AM)

quote:

15mph cross winds

I read the thread title and thought you were designing for wind. 15 mph is a mild breeze.



combatpigg -> RE: Design for Windy conditions (4/24/2008 1:02:09 AM)

A low aspect ratio wing with a medium wing loading should be able to slice its way through and penetrate best. You have to consider down wind handling too, a lead sled can fall out of the sky.



dick Hanson -> RE: Design for Windy conditions (4/24/2008 1:33:27 AM)

side area has nothing to do with how a model reacts to wind.
It has to do with how you perceive what is really happening
the ideal windy weather mode lhas instant acceleration and speed required to present an apparant straight line
this means a light model - not overkill wing area. heavy loaded models don't bounce in gusts but constant wind is an entirely different matter .



wellss -> RE: Design for Windy conditions (4/24/2008 1:46:21 AM)

A wing with lower lift slope and no dihedral. Side loads won't upset model laterally.

There are two ways to reduce the lift slope of the wing.

1. Low aspect ratio - side effect is increased induced drag, faster roll rate
2. Sweep

You could keep a high aspect ratio for less drag where wind gusts won't upset the roll as much, but then use sweep ( back or forward doesn't matter ) to reduce the lift slope. Something like the Vultee Vengence with it's swept back inboard section and swept forward outboard section was always appealing to me.



combatpigg -> RE: Design for Windy conditions (4/24/2008 2:42:18 AM)

For me, a .40 sized model is large and my best foul weather flyers are deltas.



Lomcevak Duck -> RE: Design for Windy conditions (4/24/2008 2:57:50 AM)

I'll second CP on the delta thing. My all time best windy day flyer was my Diamond Dust. A Sky-Dart spad was close second.



BMatthews -> RE: Design for Windy conditions (4/24/2008 5:35:40 AM)

Yep, I have to say that 15 isn't considered high around here either.

The only real concern for a windy weather model is that it be able to fly faster than the wind. Outside of that any semi sporty aerobatic model with the CG chosen to be a little closer to the neutral point is going to do just fine. The semi sporty implying such things as Ugly Stiks, GP Sportsters and other similar low to shoulder winged models with minimal dihedral.

Heck, I fly a big light wing loading Barnstormer biplane in winds up to 15 to 18 mph.

Some different flying techniques are needed to fly wind but most of it is just using a little common sense to modify your usual habits.



Villa -> RE: Design for Windy conditions (4/24/2008 3:23:20 PM)

I think there is a strong psychological factor involved in high wind flying. While in the air and high up, it can be a lot of fun to see the plane being tossed around. But if you are afraid of damaging the plane during the landing, that fear can drive you right into the ground. A high wind landing with gusts and wind direction changes is a very high tension moment for me. But I'm not afraid of damaging or totaling the plane. I only have SPAD planes now and they survive landing up side down, rolling over and even cartwheels. A very responsive engine with lots of power is a must.



alfredbmor -> RE: Design for Windy conditions (4/24/2008 5:16:08 PM)


quote:

ORIGINAL: subtleguru

Sometimes while one model can handle 15mph cross winds comfortably others are battered around the sky and really difficult to land. So the question is what are the characteristics that influence how well a model reacts to windy and gusty conditions.

Some possibilities

1. Wind loading ?
2. High cruise speed (relative to gust strength)
3. Large effective rudder
4. Size ?
5. Low drag

Is wind loading relevant or does is just influence cruise speed ? Likewise for size.

Needless to say I am talking about powered flight and not slope or dynamic soaring.




The best characteristics are those that have the pattern contest planes, IMHO they can beat any plane in a high wind scenario.



subtleguru -> RE: Design for Windy conditions (4/24/2008 6:44:39 PM)

Ahh ...

I imagine it is all a matter of runway width and flying ability then ?

What kind of wind speeds to people consider high then ?





alfredbmor -> RE: Design for Windy conditions (4/24/2008 8:14:57 PM)

Considering the type of plane I would put it this way:
A tiger Moth model (between 40 and 60 size) won’t like winds of more than 15 mph
A pattern Plane (Venus 40, or Venus II) will fly fine on winds around 30 mph

The ability of the pilot is a must to handle strong winds with any model but there are some "friendly" airframes that can handle high winds easier than others.

I live in an area of high speed winds and there are many pilots at my flying field who manage the wind effortless (Not my case) some of them are very good with pattern planes and have had several first places on pattern contests.

I have learned then that the wind is not an obstacle to fly sport planes but as a personal preference I use to go to the field when winds are mild.



dick Hanson -> RE: Design for Windy conditions (4/24/2008 11:03:48 PM)


quote:

ORIGINAL: alfredbmor

Considering the type of plane I would put it this way:
A tiger Moth model (between 40 and 60 size) won’t like winds of more than 15 mph
A pattern Plane (Venus 40, or Venus II) will fly fine on winds around 30 mph

The ability of the pilot is a must to handle strong winds with any model but there are some "friendly" airframes that can handle high winds easier than others.

I live in an area of high speed winds and there are many pilots at my flying field who manage the wind effortless (Not my case) some of them are very good with pattern planes and have had several first places on pattern contests.

I have learned then that the wind is not an obstacle to fly sport planes but as a personal preference I use to go to the field when winds are mild.


Having flown/designed pattern planes for years- I had to learn to fly in wind long agoand so it poses no problem to me-I get to fly when others won't .
more time for me -
Our old Tipos / ELANS etc, handled easily in wind. fast n light



Villa -> RE: Design for Windy conditions (4/25/2008 12:31:47 AM)

Someone asked what is considered "high wind". Obviously it is a relative thing and depends on experience and nerve, etc. If I am standing comfortably with my feet parallel and my hat is not ready to blow off, the wind is not bad, below 15 MPH. If I have to lower my chin strap and put one foot slightly back for better balance/support, the wind is very interesting. Sometimes I have wished I had not taken off. If you are coming in for a landing with the wind gusting and your pattern plane is going up and down about 10 feet, and rolling 90 degrees before you can correct it, and this happens during the whole approach, you know you are having a good time. If things get real bad abort and go around. But if it appears you have control even though the plane is being tossed around, continue the approach, because you know that as you get a few feet off the ground, ground effect will calm things down and the plane has a good chance of making ground contact with the main gear first. Of course, sometimes a down draft drives you into the ground. That is when a tough plane, like the SPADS I fly now, shine. The adrenalin rush after such a landing is priceless. Many people I see at the field are afraid of the wind they are afraid to damage the plane.



ILove2Bld -> RE: Design for Windy conditions (5/8/2008 8:32:03 PM)

Last year I was at the field and a guy was struggling to control his plane in a 15-20 mile an hour wind. He never did and put it in the ground off the field. It was a 40 sized low wing and not powered very well. I then took my Alpha 60 up for a spin and it has a Webra 60. It could fly into the wind pretty good. Size and power are the 2 biggest contributors to surviving in the air. This is of course basic. One could then look at these other factors and actually design something better suited.



WMB -> RE: Design for Windy conditions (5/9/2008 4:40:39 AM)

I had/have a Simple 400 w/ tt07. I was expecting it to behave badly in windy or gusty conditions. This was my smallest, but handled the wind better than any thing else. It just seemed to slice through everything.
MikeB



da Rock -> RE: Design for Windy conditions (5/9/2008 2:17:49 PM)

Low drag airframes work better than high drag.

Higher mass is harder for gusts to blow around. Not really wing loading, just mass. Wing loading only describes how much area the wing has for the weight, and that's not really that important. What is important is how heavy the airplane is. We really don't have a computed value that describes the mass/density of our models, but that's basically what would predict the performance you're after.

The Goodyear blimp is heavier than most private aircraft. It can't fly in the winds private aircraft can. Compare the density of the two and you're looking at the reason. Unfortunately, we don't have a measure of that.



dick Hanson -> RE: Design for Windy conditions (5/9/2008 4:35:13 PM)

quote:

ORIGINAL: da Rock

Low drag airframes work better than high drag.

Higher mass is harder for gusts to blow around. Not really wing loading, just mass. Wing loading only describes how much area the wing has for the weight, and that's not really that important. What is important is how heavy the airplane is. We really don't have a computed value that describes the mass/density of our models, but that's basically what would predict the performance you're after.

The Goodyear blimp is heavier than most private aircraft. It can't fly in the winds private aircraft can. Compare the density of the two and you're looking at the reason. Unfortunately, we don't have a measure of that.

gusts are unpredictible
wind is another situation altogether.
as noted earlier - speed differential is how you control wind flying
in gusty weather -the model which will correct most easily (high power to weight and set for INSTANT acceleration) is how you control gusts
most sport model flyers never develop a good feel for this
If you fly competitive aerobatics - you learn it or do poorly
the shape of the model means zip.
Some aerobatic guys STILL refer to side are of the model as being crucial to stall turns etc., because "the wind blows you around".
They learn to correct for the wind but really don't understand the issue.



aimmaintenance -> RE: Design for Windy conditions (5/9/2008 9:45:00 PM)

Last weekend we had an rc combat event and I'll have to say that the wind was as high as I've ever flown in. Not sure of the exact speed but our windsock (which by the way is supposed to be an "official" sock) was standing straight out with gusts above that.
It was almost funny to watch .25 size planes goin about 15 mph upwind then turn and go 900 mph downwind. We finally called it a day after 7 rounds and believe me, the combat guys will fly in just about anything.



mjfrederick -> RE: Design for Windy conditions (5/9/2008 9:58:40 PM)

Like Dick said before, your perception of what is happening to the airplane has no bearing on what is actually happening to the airframe. While to you the airplane that turned downwind increased it's speed, aerodynamically nothing changed as far as the airplane was concerned with the exception of the lift differentials you temporarily caused when you used ailerons and elevator to bank and turn. If airspeed had gone up or down so would the airplane. While gusts are unpredictable and can in fact cause momentary changes in airspeed, the effects of a constant-speed and constant-direction wind are all in your head.



victorzamora -> RE: Design for Windy conditions (5/21/2008 3:44:40 AM)

I don't know what's generally considered high winds, but I've flown an UltraStick 40 in 30+ mph winds. I took off at 1/4 throttle with my flaps down....in -2 feet. The wind pushed my plane backwards, I added flaps and engine, and pulled up on elevator...and it was up. I also landed it backwards, and did horizontal hovering (I dropped the flaps and gave it just enough engine to stay airborn. It was REALLY funny to see. That was a lot of fun. Oh, it handled the wind really well...and it was a high-wing.



Stick40 -> RE: Design for Windy conditions (6/5/2008 2:55:50 AM)

quote:

Last weekend we had an rc combat event and I'll have to say that the wind was as high as I've ever flown in. Not sure of the exact speed but our windsock (which by the way is supposed to be an "official" sock) was standing straight out with gusts above that.
It was almost funny to watch .25 size planes goin about 15 mph upwind then turn and go 900 mph downwind. We finally called it a day after 7 rounds and believe me, the combat guys will fly in just about anything.


Gee, we dont get 900mph down wind passes here[:)]

Stick 40[8|]



IflyPATTERN -> RE: Design for Windy conditions (6/27/2008 11:51:34 PM)

...relatively thin wings and a properly balanced airplane would greatly benefit an airplanes ability to penetrate the wind, as seen in todays pattern ships.

A tail heavy airplane will tend to drift and wander in the wind, mainly because the rudder is not effective. An airplane properly balanced or slightly forward of CG is better. just my .02$.



lnewqban -> RE: Design for Windy conditions (6/29/2008 9:20:24 AM)

I agree with Dick Hanson and Da Rock.
I fly in Florida, near to the East shore, where the air is seldom calmed.
Here is my contribution:

We don't fly; hence, our brain tends to believe that the model is feeling what we are feeling.

The model doesn't feel the wind, because it is moving within it; hence nothing changes its behavior; we just see it differently.

Gusts are another story.
In my experience, they are inexisting much higher than the tallest trees around, which interfere with the wind, and cause the gusts.
From that height up to 6 or 8 feet it is rough to fly, since unexpected gusts come from everywhere, even from above.

Below 6 or 8 feet, the speed of the wind is reduced rapidly by the friction against the ground, until becoming zero at the grass level.

Be aware of the speed of your model respect to the ground when landing.
Many crashes happen when the model, which is flying at a comfortable speed relative to the wind, but very slow respect to the ground (and the pilot) enters this zone of low air speed, suddenly finding no lift from the wings, and just stalling to crash.
The faster the wind, the closer the model to the ground, the more open the throttle needs to be.
Touching speed should be the same with high wind and with no wind.

Regards!!



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