Flying in a 7 MPH breeze? Safe/unsafe? Techniques?

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SirNomad

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Hey folks,

I've been looking for days that were almost still to take my son flying his rockets. Tomorrow is going to be the first low-wind day that I can take him out in a while, so I was wondering if we could take our model rockets out then, and what techniques do I use to fly safely? Mostly he's got low power 18mm engine powered rockets, and a few that use 13mm, some saucers, some are RTF or E2X models. (Split custody makes scheduling more complicated.)

-Michael in Tucson.
 
Hey folks,

I've been looking for days that were almost still to take my son flying his rockets. Tomorrow is going to be the first low-wind day that I can take him out in a while, so I was wondering if we could take our model rockets out then, and what techniques do I use to fly safely? Mostly he's got low power 18mm engine powered rockets, and a few that use 13mm, some saucers, some are RTF or E2X models. (Split custody makes scheduling more complicated.)

-Michael in Tucson.

7mph is no problem. If anything, just use a faster/bigger motor (B instead of A, C instead of B). Be sure to get a good line on the rocket as it will blow further.
I launch with my kids all the time in winds up to 20mph with zero issue.
 
Okay, do I aim INTO the wind a little to compensate for wind-cocking and the breeze carrying the parachute?
 
I normally aim a bit into the wind, even though it'll increase weathercocking a bit. It will indeed compensate for the drift on recovery. How much you need to do this varies for different rockets and conditions.

Always good to do a first launch on a non-critical rocket with a small engine, to get a feel for what the wind is doing. Sometimes it can be deceptive at ground level.
 
windcocking—the tendency of an unguided rocket with fins and a center of gravity located forward of its
center of pressure to turn into the wind when launched or when flying through wind direction changes.
 
7mph is no problem. If anything, just use a faster/bigger motor (B instead of A, C instead of B). Be sure to get a good line on the rocket as it will blow further.

Actually, I was gong to caution him to not use bigger engines in normal rockets, because they will fly so high that they could drift pretty far. This is a thing all beginners have to get a feel for, and often end up learning the hard way. So many fly the biggest engine, the rocket goes WAY high, and the wind carries it away. Even more of a problem when flying out of a little field as many new fliers do, having not learned yet how big of a field they may need, and not having tried to find a bigger place (finding a bigger filed is a problem for everybody).

Always critical to get a good line of sight on where the model land. But if it lands in woods, that may no do much good. If there's woods (or any other massive recovery obstacles like a river or warehouses or corn in summer) downwind, have to try to not let it drift that far.

Now for saucers, not a problem.

Really, most rockets should be able to fly fine in 7 mph wind. The ones that could have an issue would be par heavy ones for the engines used.

- George Gassaway
 
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I tend to agree with George on this one... Nothing much more discouraging to a kid than to lose a rocket on it's 1st launch. Or...the third, ask me how I know :)

I still occasionally send up an LPR or two to judge the wind before I send up anything bigger. The wind can change dramatically up at altitude compared to ground level.

That's some of the best advice I've been given...

"Fly the Field"
 
Start out with a cheap rocket you can afford to lose on a smaller motor. Also use a streamer in it as to increase chances of getting it back.
 
The only chance I get to launch rockets with the niece and nephew is Christmas week so we launch no matter what. Last time was serious wind. Launched a streamer rocket to get an idea and went from there. Started with about 5 rockets and ended up with 1.5. Trees got 2 the other 1.5 were lost to the wind. Kids ran out of energy before we ran out of rockets. A great time was had by all. Lose the rockets and build more. All part of the fun.
 
I agree with BB - swap your chute for a streamer (especially in lighter models) so it doesn't drift as far after deployment.
 
Use a higher thrust, lower impulse motor. For example, an A8 has 8N of thrust but only 2.5 Ns total impulse, as compared to a B6 which has less thrust (6) but more impulse (4.9). Higher thrust helps mitigate weathercocking. Lower impulse keeps it low and recoverable.
 
Good advice so far. I work with a youth group, and I tend to give them the smallest motor I can get away with for just that reason (there's always wind here). When we are flying in a park, I spend a lot of time gauging the wind, and try to make sure that we are set up for launching at the upwind side of the park, to give as much margin as possible.

Streamer's are a good idea. You can take a thin plastic coffee stir, cut it to the width of your streamer, glue it to one end, then run some string through to make a harness, and add a snap swivel. Then your streamers are interchangeable just like your parachutes (hopefully) are.

I will add that if you do use chutes, be sure to cut spill holes in them. I've had a few spectacular (well, expensive anyway) losses in windy conditions, which seemed to be necessary for me to learn. Other people's pain doesn't seem to work as well for me.
 
Good advice so far. I work with a youth group, and I tend to give them the smallest motor I can get away with for just that reason (there's always wind here). When we are flying in a park, I spend a lot of time gauging the wind, and try to make sure that we are set up for launching at the upwind side of the park, to give as much margin as possible.

Streamer's are a good idea. You can take a thin plastic coffee stir, cut it to the width of your streamer, glue it to one end, then run some string through to make a harness, and add a snap swivel. Then your streamers are interchangeable just like your parachutes (hopefully) are.

I will add that if you do use chutes, be sure to cut spill holes in them. I've had a few spectacular (well, expensive anyway) losses in windy conditions, which seemed to be necessary for me to learn. Other people's pain doesn't seem to work as well for me.

I do this with Qtips, COTTON sewing thread and both 1" and 2" crepe paper. They work beautifully in small parks on 5-10 mph wind days for LPR.
 
Another windy day technique involves reefing the shroud lines of a parachute. Tape the shroud lines together halfway up or so to keep the canopy from opening all the way, effectively decreasing the chute diameter temporarily. BTW any wind speed under 10 mph is a calm day in our neck of the woods. :)
 
Use a higher thrust, lower impulse motor. For example, an A8 has 8N of thrust but only 2.5 Ns total impulse, as compared to a B6 which has less thrust (6) but more impulse (4.9). Higher thrust helps mitigate weathercocking. Lower impulse keeps it low and recoverable.

Yep... That's what I was going for. The faster a rocket is traveling upwards, the less effect the wind has on the rocket. The problem begins when the parachute opens and wind carries it.
 
Use a higher thrust, lower impulse motor. For example, an A8 has 8N of thrust but only 2.5 Ns total impulse, as compared to a B6 which has less thrust (6) but more impulse (4.9). Higher thrust helps mitigate weathercocking. Lower impulse keeps it low and recoverable.

While one would think that makes sense, I recently found that Estes lists the A8-3 as having a Max Thrust of 10.7N and B6-2 has a Max Thrust of 12.1N. Additionally, Thrustcurve.org also shows the A8 having less average thrust (3.2N) than a B6 (5.0N). :confused:
 
While one would think that makes sense, I recently found that Estes lists the A8-3 as having a Max Thrust of 10.7N and B6-2 has a Max Thrust of 12.1N. Additionally, Thrustcurve.org also shows the A8 having less average thrust (3.2N) than a B6 (5.0N). :confused:

Yeah, that is pretty weird. What is that "8" supposed to mean again?

According to OR, it looks like an A10-3T would actually get the rocket off the rod the quickest. Interesting!
 
While one would think that makes sense, I recently found that Estes lists the A8-3 as having a Max Thrust of 10.7N and B6-2 has a Max Thrust of 12.1N. Additionally, Thrustcurve.org also shows the A8 having less average thrust (3.2N) than a B6 (5.0N). :confused:

Yeah, that is pretty weird. What is that "8" supposed to mean again?

According to OR, it looks like an A10-3T would actually get the rocket off the rod the quickest. Interesting!

Bad old historical reasons, inertia, the expense of changing ALOT of printed and electronic documents, no sims or portable super computers (smart phones) back in the day. The best explanation I've seen is here: https://www.rocketryforum.com/showthread.php?54916-Confused&p=540405#post540405
 
I would say that it was an old typo going years back to when the A3 first showed up and everyone thought it was A8! :D

Back on topic, I agree with what the others say...try a few smaller rockets first to get an idea of the wind and how it's affecting the rockets and/or use streamers and smaller/reefed chutes.

It's actually quite an art to figure out the right rocket (how much does it weathercock?), motor, chute size and rod angle to get your rocket back close to the pad on a windy day...any one of those items being "wrong" can send it very far away.

Here's an Apogee technical article on wind caused instability which has recommendations to use high thrust/short burn motors and taller launchers.

An Estes' Model Rocketry Tech Manual recommends: "PROBLEM(5) Parachute deploys, but wind carries rocketaway.SOLUTION: In windy conditions replace the parachutewith smaller ‘chute or streamer. Or, “reef” the ‘chute byapplying a wrap of tape around the parachute shroud lines,half-way up; this prevents the ‘chute from opening fully so themodel falls faster. Or, cut a spill hole in the center of theparachute."

Good luck and I hope you have a great launch!
 
Yeah, that is pretty weird. What is that "8" supposed to mean again?

According to OR, it looks like an A10-3T would actually get the rocket off the rod the quickest. Interesting!

I made a Youtube video showing an A8-3 and A10-3T in the same rocket and the A10-3T was actually very impressive.
 
I'm one of the many who tosses up a beater rocket to judge winds before getting serious for a days launch. Unless I'm out of them, I always use an A10-3T in the beater Alpha with stock parachute. Better performance out of the A10 mini motor than the A8 regular motor, and you get four of them for about the same price (depending on where you buy) as three A8s.
 
I did buy a bulk pack of the A8-3s from Hobby Lobby with a 40% coupon a few weeks ago.
 
Use a higher thrust, lower impulse motor. For example, an A8 has 8N of thrust but only 2.5 Ns total impulse, as compared to a B6 which has less thrust (6) but more impulse (4.9). Higher thrust helps mitigate weathercocking. .
Good general theory. But in this case, a misunderstanding of the actual thrust levels of an A8 vs a B6.

The A8 has a peak thrust of about 10 Newtons, then drops to sustainer of about 2.25 Newtons.
A8_thrustcurve_0.jpg

The B6 has a peak thrust of about 12 Newtons, then drops to a sustainer of about 4.7 Newtons.
B6_thrustcurve_1.jpg

The A8 is therefore somewhat misleadingly labeled. Its average thrust is 3.18 Newtons. While the B6 average thrust is 5.03 Newtons.

Now, the "A10" actually has a peak thrust a bit over 12 Newtons, but it is so short, and the sustainer so wimpy, that its average thrust is 2.35 newtons. But the A10 definitely gets a 13mm rocket moving a lot faster than an A3. And probably gets a rocket moving faster than an A8 (My Rocksim is out of commission at the moment)

So, in the examples given, an A8 would not take off faster than a B6 powered rocket does. Of course, when it is windy, there are good reasons to use smaller engines to not fly as high and therefore not drift as far as mentioned earlier (" Lower impulse keeps it low and recoverable"). But the rocket won't fly better in wind on an A8 than a B6, it'll fly worse because it has lower thrust. But unless the wind is really bad or the rocket is particularly heavy or tends to weathercock a lot, it's a reasonable compromise to fly on a lesser engine like A8 than B6. Or B6 rather than C6, and so on.

This is why it is so important to check and compare thrust curves, not just go by the engines "name" average which can sometimes be misleading. A good source to check is the NAR website's certified engine list: https://www.nar.org/standards-and-testing-committee/nar-certified-motors/

In addition to some basic information, there are also links to PDF files that have more test-firing data, as well as actual thrust curves which may be different from manufacturer's advertised thrust curves.

- George Gassaway
 
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Nearly ANY wind scares me, as I generally fly in a smallish field.
That said, I have learned to make some really nice/efficient streamers, and using lightweight glass on everything from 13mm on up insures that landings are kind to my airframes.

Streamer for Centuri 3232 2015-04-20 001.jpg

[video=youtube;7DUWn3hupgY]https://www.youtube.com/watch?v=7DUWn3hupgY[/video]
 
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Use a higher thrust, lower impulse motor. For example, an A8 has 8N of thrust but only 2.5 Ns total impulse, as compared to a B6 which has less thrust (6) but more impulse (4.9). Higher thrust helps mitigate weathercocking. Lower impulse keeps it low and recoverable.

When it was originally certified, the A8 had 8 Newtons of average thrust. it has been redesigned over the years and no longer has 8 N average thrust, but it has not been re-identified. It is still a good motor, but always look at the real modern thrust curves and data on the NAR website.

If using a 1/8" rod, use a 4 foot long steel rod available cheap from Home Depot or Lowes. Put a weight on 2 legs of the launch pad to prevent tipping.

Using a 4 foot long steel rod is also fine for most 3/16" launch rod rockets, but if using E9 motors, you should really use a 6 foot long 1/4" diameter steel launch rod to allow the rocket to build up more speed before leaving the rod.
 
If using a 1/8" rod, use a 4 foot long steel rod available cheap from Home Depot or Lowes. Put a weight on 2 legs of the launch pad to prevent tipping.

Using a 4 foot long steel rod is also fine for most 3/16" launch rod rockets, but if using E9 motors, you should really use a 6 foot long 1/4" diameter steel launch rod to allow the rocket to build up more speed before leaving the rod.

A little off the original subject, but when I started getting into the composite motors, I went with a 1010 rail. Rod whip can be nasty, depending on how hard you hit them.

Not on any of my rockets, but I swear I've seen -rail whip- at some of the High Power launches. That's impressive!
 
no need to swear, all you need to do is watch a 'slo-mo' vid of a Vmax launch, or watch the smoke trail...a lot of those birds have a wiggle as they leave the rail.
Rex
 
Flying into a 7 MPH should be no problem provided you have a big enough landing area and the rockets will not go extremely high. Tilt the the launch rod into the wind slightly and don't use too big of a a parachute. Parachutes with spill holes are a good idea.

Rocketron
 
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