Wind and rockets

[Jimbooregon]

Hi all,
Here in Scotland it's windy a lot. Other than using lower power engines what should I look for in a kit? I'm thinking about a Big Bertha kit will a a smaller chute and or center hole help in keeping it closer to the launch site?
You're ideas all welcome.
Cheers
James

 

[Hobie1dog]

Fat rockets, smaller parachutes than come with the kit/or, streamers

 

[Funkworks]

Maybe one of these, I don't know, I'm thinking of getting one:

https://www.amazon.com/wind-meter/s?k=wind+meter
Anyone has recommendations for a wind meter while we're at it?

 

[mh9162013]

Maybe one of these, I don't know, I'm thinking of getting one:

https://www.amazon.com/wind-meter/s?k=wind+meter
Anyone has recommendations for a wind meter while we're at it?

Can't really go wrong with Kestrel (which is what I have), but I'm sure there are cheaper knock-offs that do well enough. I just don't have any experience with those.

 

[mh9162013]

Hi all,
Here in Scotland it's windy a lot. Other than using lower power engines what should I look for in a kit? I'm thinking about a Big Bertha kit will a a smaller chute and or center hole help in keeping it closer to the launch site?
You're ideas all welcome.
Cheers
James

Those are good suggestions, as are the ones from @Hobie1dog.

Another option is to change your launching point and angle to compensate for the wind. It's not easy to do, especially with inconsistent wind, but I've done it a few times when launching in a small baseball field at my local park.

 

[SolarYellow]

Read up on wind-caused instability. Going with smaller motors isn't always better if they mean a lower speed when leaving the launch rod.

 

[JimByrne]

When is it windy? I live in the Arizona desert, and it is calm or a mild wind early in the morning so that's when we launch. When the wind picks up we go home.

 

[Voyager1]

Hi all,
Here in Scotland it's windy a lot. Other than using lower power engines what should I look for in a kit? I'm thinking about a Big Bertha kit will a a smaller chute and or center hole help in keeping it closer to the launch site?
You're ideas all welcome.
Cheers
James

You could use OpenRocket or Rocsim to simulate various models with different motor combinations and wind speeds to analyse their behaviour. This allows you to try before you buy.

You can also adjust your chute size by reefing the shroud lines to prevent it from opening fully, thereby increasing the descent rate and preventing excessive drift.

Mare sure your velocity off the rod is at least 3-4 times the crosswind component.

 

[Splinter]

This site is useful for getting wind speeds on the day - https://www.windy.com/?54.265,4.966,5,m:feHaf2v

 

[Greg Furtman]

I've cut holes in the center of most of my parachutes and it seems to work well to keep the rocket nearby.

 

[Jimbooregon]

Splinter great link, thanks! Greg and all, some good ideas, much appreciated. Cheers

 

[BABAR]

If somebody mentioned streamer models I missed it.

Also modification of fin attachment or design. Fins with a forward swept TRAILING edge (think Estes Alpha with fins reversed) survive the more rapid descent of streamers, or smaller chutes or bigger spill holes or reefed chutes, as the initial ground impact is the motor casing and not the fins. You may need to add a touch or nose weight to maintain stability.

Also by safety code,

“I will launch my rocket outdoors, in an open area at least as large as shown in the accompanying table, and in safe weather conditions with wind speeds no greater than 20 miles per hour.” (32 km/hr)

With winds over that, it’s just no fun. Chances of weathercocking are really high, you will likely lose the rocket and outfly the field, potential for personal injury or property damage or fire is high (severe weathercocking can result in ejection charge or even delay burn occurring on a rocket already returned to earth, never a good thing.

Also consider saucers and monocopters.

Have fun!

 

[jadebox]

Build rockets that can descend quicker but safely and without damage. For example, tube or ring-fin rockets can use a smaller 'chute or streamer so they can fall faster and land without damage or causing damage.

Edit: And as Barbar said earlier, some fin shapes and positions are less prone to breaking on landing. So those rockets can be allowed to descend quicker and, therefore, drift less.

 

[Jimbooregon]

Thanks for the continued replies. I'm going to continue to research this.
Cheers

 

[Tractionengines]

[ Sorry for long post, but this is the beginners forum so, I am giving a long explanation. ]

Someone mentioned angling the launch rod... IF you do this, read up and talk to people with lots of experience...otherwise near straight up is usually best. ie. you said Big Bertha as an option, and "small" motors to help with wind.

Here is what "could happen" with that arrangement. The Big Bertha is an over stable rocket. This means it will naturally turn INTO the wind. This is because the wind pushes the fins from the side, so the nose points into the wind. Add a low thrust motor so its not going fast enough leaving the rod, and this wind induced turn is greater. This is called Weathercocking.

NOW suppose you are concerned with the wind blowing it out if your field while under chute... so you angle the launch rod into the wind, and use a low thrust motor. The natural turn from Weathercocking ADDS to your rod angle and your rocket goes at a near horizontal flight into the wind. It doesn't get much height, so your delay is too long, and goes off while your rocket has a lot of speed and is very low to the ground. This can cause the shock cord to tear the body tube (called a "zipper"). Worst case the rocket hits the ground before the ejection charge fires, and now its a fire hazard.

As you get experience with different rockets, in different winds, this will make more sense... also get the rocket simulation/design programs that can calculate this, but that more advanced. The simulation has to be built and entered correctly, to give good information. Rocksim (purchase) and Open Rocket (free)

Summary:
1 - big fins: don't angle the launch rod into the wind. Ok to do some for smaller fins as the natural wind induced turn will be less. (Really big fins, maybe a little angle DOWNWIND could be useful.)
2 - low thrust motors leave the rod slower and wind has more effect. Use higher thrust, lower total impulse motors when its windy.
3 - if its too windy fly kites.

 

[Jimbooregon]

Thanks makes sense now!!

 

[neil_w]

Build rockets that can descend quicker but safely and without damage. For example, tube or ring-fin rockets can use a smaller 'chute or streamer so they can fall faster and land without damage or causing damage.

Edit: And as Barbar said earlier, some fin shapes and positions are less prone to breaking on landing. So those rockets can be allowed to descend quicker and, therefore, drift less.

I think this is the biggest factor. The faster the rockets can come down, the less time they'll have to drift. Build for fast descent and landing durability.

Also don't forget saucers and the like. They're a fun supplement to the other more traditional rockets, and they land close in almost any conditions.

 

[Huxter]

Noone mentioned a Jolly Logic chute release. They're a bit pricey, but helps on small fields. (I wish I had experience w it)

https://jollylogic.com/products/chuterelease/

 

[DaHabes]

Read up on wind-caused instability. Going with smaller motors isn't always better if they mean a lower speed when leaving the launch rod.

Ditto. In windy conditions you need MORE motor to make sure the rocket goes up and doesn't weathercock into the wind, and never, ever point the launch rod into the wind - it makes weathercocking worse.

 

[kuririn]

Another option:
Don't launch when it's windy.
Know when to stand down.

 

[mh9162013]

never, ever point the launch rod into the wind - it makes weathercocking worse.

This is false. While it's true that you may usually want to avoid pointing the launch rod into the wind, you'll sometimes do so to get even more weathercocking to compensate for windy conditions. But as others have discussed, you need to be careful when doing this and know exactly what you're doing.

 

[SolarYellow]

Ditto. In windy conditions you need MORE motor to make sure the rocket goes up and doesn't weathercock into the wind, and never, ever point the launch rod into the wind - it makes weathercocking worse.

High thrust, especially high initial thrust, to ensure it gets launched at as high a speed as reasonably possible. But not a lot of N-sec, so it doesn't go too high. This may be a place where the Quest Black Max motors beat BP.

 

[4regt4]

To add to what others have mentioned about thrust and wind.....

If it's windy, I reach for Blue Thunder motors. For example, the E18W and E28T motors sim out to similar altitudes for many of my rockets, but using OpenRocket's side profile plot, you will see that the E28T flies straighter.

Hans.