Why rail/rod angle is important...

[EXPjawa]

I'm going to paint you a picture: imagine, at a typical club launch, in an undisclosed location at an undisclosed time, you've got your typical spread of fliers, spectators, vendors, etc. Its a bright day, a bit of patchy cloud cover, mid-70s temps. Sounds ideal, except the wind is gusty and we've got frequent bursts that are probably in the 20-25mph range. Are you with me so far? Flyers are on the flight line, and the vendors are back from the line a bit.

Now say, hypothetically, an undisclosed flyer (not me!) attempts to launch an undisclosed low-power 2-stage rocket. The wind is up, and with the extra fin area of the booster, it kicks up wind a bit - back over the flight line. Except the sustainer doesn't light, so the rocket continues in a ballistic flight path - in the wrong direction. Said rocket might strike the roof of an undisclosed vendor's trailer, causing damage. Sound far fetched?

Since no one was hurt (even the rocket was undamaged), this is an excellent reminder that even a light, little rocket made of cardboard and plastic carries enough kinetic energy to do damage. Sure, the roof skin of a box trailer is fairly thin aluminum, but the roof of your car isn't much stronger in that situation. Not to mention a pop-up canopy or the roof of someone's head... I'm not one to go all fussy with rules, but this underscores why its important to make sure you're angling rockets properly!

 

[rstaff3]

Yup, ideally you should set up so the wind is parallel to the flight line. In this case I recommend leaving the model in place and sealing around the cone on each side.

 

[djkingsley]

Poor Gloria is going to have find a safer place to hide.

 

[rstaff3]

Dang, I hadn't noticed whose trailer that is. They have a rip in their pull out canopy thanks to one of my fins when a rocket drifted over. Same issue - bad wind direction. I offered to pay for the repair but they said not to worry about it. Great folks!

 

[TangoJuliet]

:surprised: That certainly could have been much worse! Perhaps the LCO should also be more aware before allowing a launch to take place, especially when winds and multi-stagers come into play.

 

[cwbullet]

Wind can be your friend and enemy. Mostly the latter.

 

[LRIPbros]

My son has that rocket (Estes Flying Colors) and with the booster it is a squirrelly flyer even in great conditions . Glad no one was hurt.

 

[djkingsley]

Dang, I hadn't noticed whose trailer that is. They have a rip in their pull out canopy thanks to one of my fins when a rocket drifted over. Same issue - bad wind direction. I offered to pay for the repair but they said not to worry about it. Great folks!

She posted a picture on Facebook an hour or so ago.

 

[EXPjawa]

She posted a picture on Facebook an hour or so ago.

Well, I don't doubt that lots of pictures were taken. It seemed like everyone nearby was...

 

[dave carver]

Here we have the Snake River Canyon to our left shoulder where the sun is. Behind us is the Orchard Military Training Range (Enter at Your Own Risk). Over the right shoulder is North and a few (very few) farms for around 20 miles. We face West...where the wind comes from. I have lobbied (carped) to change this but...I very rarely fly anymore... When I do it's small rockets, little motors and small fields where I stand a good chance of drawing kids, they make great rocket retrievers...once you get them trained

 

[markkoelsch]

There are a number of potential issues here.

Let's start with the rocket. If the wind is 20 mph, what should you thrust to weight be? It has to go up. The NAR did a study on this a few years ago. Look it up.

Secondly, let's assume wind is 20-25 mph as an average. I believe the rule is 20+ the range should be closed. If it is averaging in the teens with gusts over 20 not sure what the exact answer would be. I would ask this- if the rules state that the range will be closed with a 20 mph wind then this happens would the insurance company view this launch as being compliant with the rules? Would the insurance company pay a claim?

 

[o1d_dude]

First thing that caught my eye was the statement that the winds were 20-25 mph.

According to the book, launch operations cease with those wind speeds, amirite?

 

[markkoelsch]

First thing that caught my eye was the statement that the winds were 20-25 mph.

According to the book, launch operations cease with those wind speeds, amirite?

My point exactly. Ask a leading question. Who was running this launch?

 

[Q-Aero]

Dual stages in wind of 20-25mph is a lack of judgment from the rocket owner and especially the RSO.

 

[mpitfield]

I have never noticed, however would it not be easy and affordable for a club to acquire a portable weather station that could be situated, with the "thingy that spins" for the wind speed slightly elevated at the LCO table?

 

[Paradox_2112]

Thank goodness no one was hurt. A trailer full of composites and a hot ejection cap can be a very bad combination.

 

[jderimig]

Secondly, let's assume wind is 20-25 mph as an average. I believe the rule is 20+ the range should be closed. If it is averaging in the teens with gusts over 20 not sure what the exact answer would be. I would ask this- if the rules state that the range will be closed with a 20 mph wind then this happens would the insurance company view this launch as being compliant with the rules? Would the insurance company pay a claim?

First thing that caught my eye was the statement that the winds were 20-25 mph.

According to the book, launch operations cease with those wind speeds, amirite?

My point exactly. Ask a leading question. Who was running this launch?

Dual stages in wind of 20-25mph is a lack of judgment from the rocket owner and especially the RSO.

Boy this group triggers easily. The launch was at Geneseo, data from one of the windiest places in town (Putnum Hall, tall building at SUNY Geneseo) shows that sustained wind never exceeded 15mph but there were gusts that exceeded 20mph. However gusts are not easily measured by amateurs without weather stations equipped for that. If intermittent wind gusts over 20mph requires a launch closure then there would be fewer legal launches anywhere.

Lets avoid rushing to convict flyers and clubs without any true data shall we?

 

[rstaff3]

The wind direction issue is a good one even if the wind was below what was originally stated. I've seen similar close calls when the ground wind was closer to 10. I'm surprised how a far a lawn-darting rocket can be blown. If the wind takes your rocket over the crowd, whether due to drift or weather cocking, the risk of an incident goes up. Unfortunately, the field layout is generally dictated by the access roads.

 

[jderimig]

The wind direction issue is a good one even if the wind was below what was originally stated. I've seen similar close calls when the ground wind was closer to 10. I'm surprised how a far a lawn-darting rocket can be blown. If the wind takes your rocket over the crowd, whether due to drift or weather cocking, the risk of an incident goes up. Unfortunately, the field layout is generally dictated by the access roads.

Agree, and for a large regional launch the only chance for practically optimizing the flight line relative to the wind is on the first day. Geneseo has another constraint, it is verboten to fly rockets towards the Historical Aircraft museum regardless of where the flight line is drawn.

 

[OverTheTop]

Sounds like tilt lock-out for sustainer igntion is a good idea...

I always liked the idea of magnetic apogee detectors. Quite simple, and automatically put the brakes on when they go too far away from up.

 

[jderimig]

Sounds like tilt lock-out for sustainer igntion is a good idea...

I always liked the idea of magnetic apogee detectors. Quite simple, and automatically put the brakes on when they go too far away from up.

It was an Estes rocket.

 

[EXPjawa]

As the one who started this mess, I feel obliged to note that I pointed out that it was the gusts that were 20+. The sustained winds were a bit less than that, but the gusts were frequent enough that I sat back and just watched after only two launches of my own. And those launches of mine were sub-350'. It wasn't worth chasing that far to me. But others were flying quite a bit, and a number of flights went back over the line, though nowhere near the hangers. I will also point out that the flight line orientation is largely dictated by the configuration of the airfield, and the normal wind direction is parallel to it. Today's wind was not the typical direction. As such, angles and flights probably should've been closer regulated.

 

[markkoelsch]

Boy this group triggers easily. The launch was at Geneseo, data from one of the windiest places in town (Putnum Hall, tall building at SUNY Geneseo) shows that sustained wind never exceeded 15mph but there were gusts that exceeded 20mph. However gusts are not easily measured by amateurs without weather stations equipped for that. If intermittent wind gusts over 20mph requires a launch closure then there would be fewer legal launches anywhere.

Lets avoid rushing to convict flyers and clubs without any true data shall we?

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Triggers easily? Not really. If saying let's assume 20-25 mph the range should be closed is considered easily triggered, then you need to consider your trigger point. I never said the wind was that, but was bringing it up for discussion. If it was 20+ mph then the range should have been closed. It is that simple.

I agree that the only good way to judge is to actually be measuring the wind velocity.

As to the thrust to weight ratio vs wind I am totally justified in my statement.

 

[jderimig]

Triggers easily? Not really. If saying let's assume 20-25 mph the range should be closed is considered easily triggered, then you need to consider your trigger point. I never said the wind was that, but was bringing it up for discussion. If it was 20+ mph then the range should have been closed. It is that simple.

No argument with ^this hypothetical.

My point exactly. Ask a leading question. Who was running this launch?

Then you converted this hypothetical into an implied fault of the people running this launch. In my opinion this wasn't fair.

 

[markkoelsch]

No argument with ^this hypothetical.




Then you converted this hypothetical into an implied fault of the people running this launch. In my opinion this wasn't fair.

Fair enough. I understand how it could be read that way- I really was asking to find out more information.

 

[DavidMcCann]

Agree, and for a large regional launch the only chance for practically optimizing the flight line relative to the wind is on the first day. Geneseo has another constraint, it is verboten to fly rockets towards the Historical Aircraft museum regardless of where the flight line is drawn.

this is one of my issues with large launches (I don't like them). You've got so much equipment and cars setup, it's impossible to adjust for wind. And given the choice between shutting down or flying over the crowd.... well we all know how that goes.

Just because its not practial tonlaunch safely, does not excuse the rules.

 

[jderimig]

this is one of my issues with large launches (I don't like them). You've got so much equipment and cars setup, it's impossible to adjust for wind. And given the choice between shutting down or flying over the crowd.... well we all know how that goes.

Just because its not practial tonlaunch safely, does not excuse the rules.

I am not excusing the over-crowd-flight rule for practicality at all. However the flight line being parallel to the wind is not a rule, its a method.

If I had nickel for every time a club changed the flight line with a windshift I would have......still waiting for a nickel.

 

[modeltrains]

Wind can be your friend and enemy. Mostly the latter.

With kites is about 50/50.

 

[OverTheTop]

It was an Estes rocket.

I have a magnetic apogee detector that fits in an 18mm cardboard airframe. Would that help :wink:

 

[jderimig]

I have a magnetic apogee detector that fits in an 18mm cardboard airframe. Would that help :wink:

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