The day a C6-5 almost got me killed

[dragon_rider10]

I had this story posted in another thread, and it seemed out of place there, so I am creating it's own home. It's the SR-71 story if you've already read it. It took a while to write and I'd hate for anyone to miss its life lessons, so here it is::happydeer:

The Day a C6-5 Almost Got Me Killed.

It was a slightly breezy day in February or March. I had flown all sorts of rockets in much windier conditions with no ill effects. Well, I had my nice new Estes SR-71 Blackbird, ready for her second or third flight. I had flown her twice the day prior. Again no problems. The park is in a weird area, though, that the wind direction seems to change frequently. A bowl effect or something caused by the trees.

So we got to the middle of the field you see above. About 300 feet maybe to the left is a soccer game. Girls about 11ish. Lots of parents around. We're fine, no big deal, they're way way off. Concern didn't even cross my mind.

Well, set up the Blackbird on the pad with a C6-5, angle it into the breeze slightly as I normally do to keep drift down and grab the controller. Checking the sky and immediate area near the site, all clear, 3- 2- 1....

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The Blackbird screams into the sky and gets about 30 feet in the air, when it weathercocks to the...you guessed it...left. In slow motion, I can still see that thing go horizontal.

Now this is a fairly intimidating kit. Knifelike nosecone, all black, nicely weighted in the front, it's got some heft. And now it's blasting in the direction of the soccer game at who knows...150mph?

I'm praying..."please pop, please pop, please pop. What did I put in it... C what god i hope not a 7?" 1 second 2 seconds 3 seconds.

Does it eject? No luck. It flies under full power like a Maverick into the field, right in the middle of the game. Buries itself 5 inches into the dirt and then pops the chute. No one is hurt, thank God. It seriously could have been bad.

Well, after running up to it and stomping it to death, the fathers of the soccer players look in my direction. I am already boldly walking in their direction to apologize profusely, but I see the look on their faces. Hell hath no fury like it. (And rightly so. If it was my kid out there and this guided missile almost skewered her...i'd be pretty P.O.'d too)

One guy, the coach, is quite red as we close the gap, gripping my poor nosecone and chute. "Did you do that?!" He asks me. "Yyy...yes," I stammer. Ignoring me he continues, louder, "Did YOU do THAT?!?" "Yes, I'm sorry, I don't- " "This THING," holding the cone in my face like a gun, "came 5 inches of my kid's temple!!"

The other guys are coming up behind him, looking more like they were planning on having to hold him back so he doesn't jam the SR-71 into MY temple.

"I'm sorry, sir, my name is John, and I don't know what happened. They usually fly straight up. I, I am really really sorry." I was really hoping he wasn't going to kick my tail in front of 50 families and my own kid.

"Well, what you are going to do is march over to that field and APOLOGIZE to my players and all their families."

"Yes sir I'd be happy to." I did just that. The parents didn't seem to be too worried about it at all, and the kids were just doing their thing.

Well...for about 6 months I steered clear of launching anything at this field and found other places to fly rockets. Now, ever cautiously, I am flying here again, but only when there are no games or even small groups of people.

Oh, what about the SR-71? Well, after picking up its crushed, charred hulk from the field, and humbly taking the nosecone back. I realized that this kit might not be the one for me. That was of course, until i saw the thread on clustering one the other day.

 

[Verna]

I'm sorry to hear about your problems but I have to say in over 20 years of flying the Estes kit in multiple configurations including clustered, I have never seen or experienced anything close to what you described and it brings all kinds of questions to mind.

Was there an autopsy performed? The SR-71 is a heavy rocket even on a C. On a single C6 it doesn't go high, fast or far, even if ballistic.

Possible causes:

1. Did you use a C6-7? The longest delay for a single engine Estes SR-71 kit would be a C6-5.
2. Was the rod dirty and clogged the lug, so that it was hanging on the rod in a manner that it affected direction or angle as it left the rod?
3. Could it have been rod whip or was the rod loose and wiggled?
4. What do you think the surface wind speed was at launch?
5. Did it lose the tail or any fins at some point?
6. Do you still have the engine?

There are other questions but these give you some starting points to figure out why it flew the way it did.

I understand you were scared silly but try to remember when things go wrong to try and figure out why it happened and don't destroy the things that will lead you to the answers.

Better luck with the next one.



Verna
www.vernarockets.com

 

[MysticalRockets]

The second he started waving it at me, my cell phone would have been out and dialing 911.

But this is just me. My tolerance for soccer people tends to be very low after some bad experiences.

 

[dragon_rider10]

Unfortunately, the rocket was destroyed by the soccer coach before I could figure out what went wrong. The best I could come up with was that on a previous launch a day or two earlier, i had popped off one of the large tailfins and reattached it. The reattached fin passed my quality check for alignment, but if it was attached at an even an acute angle, I could see it creating some sort of pressure that would make the rocket go unstable or arc over. The wind condition at surface was slight, perhaps a higher gust at elevation?

I do not have the engine or the rocket still in my collection. I'm fairly sure it was a C6-5, but this was several months ago so I do not know for sure.

 

[hcmbanjo]

Hey dragon_rider10,
I was always tempted to build one of the Estes SR-71s - until I saw a few fly.
I've only seen one that had a vertical flight!
In seems in most launches, it'll go straight up for 50 feet, turn and go horizontal. It then looks like the nose is turning up and is trying to get a little more height. Sometimes it blows the parachute while in the air others on the ground. it's a 50 - 50 proposition.
Heads up!

 

[shreadvector]

You have described the number one reason for Model Rocket launching to be banned in public parks and school yards. Banned by policy or local regulation.

How to prevent this: NEVER launch any model rocket that can ballistically reach anyone who is not involved in/spectating or aware of the model rocket launch. ANY activity in a public park that could result in injury to other non-participating park patrons is forbidden.

That is why parks require use permits and/or rental fees to secure and reserve adequate space for activities. in the case of Moel Rockets, this would include launch AND recovery areas - and recovery area includes the entire possible range of crash/drift area.

 

[dragon_rider10]

Hey dragon_rider10,
I was always tempted to build one of the Estes SR-71s - until I saw a few fly.
I've only seen one that had a vertical flight!
In seems in most launches, it'll go straight up for 50 feet, turn and go horizontal. It then looks like the nose is turning up and is trying to get a little more height. Sometimes it blows the parachute while in the air others on the ground. it's a 50 - 50 proposition.
Heads up!

Which is why I can't understand why it's still in production. Because of this incident, I've quit launching anything that's not a simple 3-4FNC anywhere other than Bunnell. The incident almost turned me off of rocketry for good, and is why I haven't had any real interest in anything more powerful than an E motor.

Shreadvector, I certainly understand the ramifications of the incident, and I was literally terrified to be 'that one guy' who gets rocketry banned. I don't consider myself a careless rocket guy, and do my best to adhere to the NAR code. Even though it's written in a lighthearted manner, I posted it to remind folks that even when their rockets are built well and conditions are seemingly OK, things can still go haywire. Extra caution is never a waste.

 

[shreadvector]

Which is why I can't understand why it's still in production. Because of this incident, I've quit launching anything that's not a simple 3-4FNC anywhere other than Bunnell. The incident almost turned me off of rocketry for good, and is why I haven't had any real interest in anything more powerful than an E motor.

Shreadvector, I certainly understand the ramifications of the incident, and I was literally terrified to be 'that one guy' who gets rocketry banned. I don't consider myself a careless rocket guy, and do my best to adhere to the NAR code. Even though it's written in a lighthearted manner, I posted it to remind folks that even when their rockets are built well and conditions are seemingly OK, things can still go haywire. Extra caution is never a waste.

I absolutely understood why you posted this and that you were indeed terrified.

This is an excellent reminder to all readers that things can go wrong and the NAR Model Rocket Safety Code is a MINIMUM. The field size limits are the bare minimum required when everything is perfect.

Our "free" launching ends this Sunday. We launch in a huge county regional park as a co-sponsored activity. It has been free (other than the vehicle fee to get in the park), but with the economic situation, they are now going to charge all cosponsored activities 25 percent of the normal rent. This starts in January and we will have a new small fee ($2) to launch (waived for special categories of people who already support the club financially as specified in our 2010 information that will be mailed and posted next week), Naturally, our biggest concern over the years has been the perception (or reality) that rockets would reach non-participating park patrons. We have a VERY good track record.

 

[Donaldsrockets]

"Well, what you are going to do is march over to that field and APOLOGIZE to my players and all their families."

Wow, even in a situation like this, you had a lot more patience than I would have.

I would have apologized like you did but I probably would have told him to stop the yelling and even though this was an accident and that I'm an adult and I expect to be treated like one.

Then I probably would have called him a few names that I won't mention here. I tend to have a very short fuse when it comes to belligerent people like this.

Great story though, thanks for posting it.

 

[spacecadet]

I think I'd at least have reported him for criminal damage.

 

[Gillard]

my main flying field (low power only) in next to a golf course, and i've had a few rockets drift onto the course, perhaps ten or so out of about 500 launches. nearly everytime, the golfers have been very friendly, one our two stop to chat about rockets, on a few occasions i've had a golfer looking a bit irrate, but no one has ever said a bad word to me. one one occasion a golfer came storming over, but changed his mind when he got closer. i suppose that's the difference between golfers and soccer guys - mind you, it does help that I'm a lot bigger than the average guy!

 

[MarkII]

I did a quick skim of the reviews of this kit on EMRR (there are several), and most report the weathercocking issue almost exactly as you described. One comment mentioned that after a few flights the forward edge of the body wrap started to lift, which could potentially cause it to "catch air" during the boost. The commentator suggested that this could be a cause of the model's sudden, unexpected tendency to weathercock after a history of straight flights. Various remedies for this lifting of the wrap were described. But my guess is that any model that has this much wing area will have a pronounced tendency to weathercock anyway, and so it should probably only be launched in a large field when there is little or no wind.

Someone also mentioned modifying the kit to take 24mm motors. The idea for that was to give the model much more thrust at lift-off, so that it would be less vulnerable to crosswinds. I don't know very much about the kit myself, though; I have never owned one and I have never seen a launch of it.

MarkII

 

[shreadvector]

24mm motors is a bad idea as that will add weight in the aft end and destabilize it.

Simply use an Aerotech D10 or D21 motor and the weight will not increase, yet the liftoff thrust will be much higher.

Also, a 1/8" x 4 foot long steel launch rod would be a good idea.

I did a quick skim of the reviews of this kit on EMRR (there are several), and most report the weathercocking issue almost exactly as you described. One comment mentioned that after a few flights the forward edge of the body wrap started to lift, which could potentially cause it to "catch air" during the boost. The commentator suggested that this could be a cause of the model's sudden, unexpected tendency to weathercock after a history of straight flights. Various remedies for this lifting of the wrap were described. But my guess is that any model that has this much wing area will have a pronounced tendency to weathercock anyway, and so it should probably only be launched in a large field when there is little or no wind.

Someone also mentioned modifying the kit to take 24mm motors. The idea for that was to give the model much more thrust at lift-off, so that it would be less vulnerable to crosswinds. I don't know very much about the kit myself, though; I have never owned one and I have never seen a launch of it.

MarkII

 

[MarkII]

my main flying field (low power only) in next to a golf course, and i've had a few rockets drift onto the course, perhaps ten or so out of about 500 launches. nearly everytime, the golfers have been very friendly, one our two stop to chat about rockets, on a few occasions i've had a golfer looking a bit irrate, but no one has ever said a bad word to me. one one occasion a golfer came storming over, but changed his mind when he got closer. i suppose that's the difference between golfers and soccer guys - mind you, it does help that I'm a lot bigger than the average guy!

A group of adults playing a round of golf may be more forgiving, but when fathers go into "daughter protection mode" their reactions can be unpredictable. :y:

MarkII

 

[Donaldsrockets]

I have an Estes SR-71 and it's flown okay for the most part but other than using an 18mm AT motor like Fred mentioned which would be a very good idea, the only Estes motors I would recommend would be the B6-2 and C6-3.

I personally like the Sunward jet fighters better. First of all, they're much bigger, second, they're much better designed and as a result, fly better and third, they can be built with your choice of an 18mm or 24mm MMT.

Although if you select the 24mm option, clay weight IS required.

 

[MarkII]

24mm motors is a bad idea as that will add weight in the aft end and destabilize it.

Simply use an Aerotech D10 or D21 motor and the weight will not increase, yet the liftoff thrust will be much higher.

Also, a 1/8" x 4 foot long steel launch rod would be a good idea.

I agree about the added tail weight caused by the more massive 24mm motor. The person who suggested this also mentioned adding extra nose weight as part of the modification. I also agree that if the intent is give the SR-71 a stronger boost, then 18mm composite D motors would seem to be the better and more obvious answer. And using a longer guide rod is also a good idea.

MarkII

 

[NjCo]

Hey dragon_rider10,
I was always tempted to build one of the Estes SR-71s - until I saw a few fly.
I've only seen one that had a vertical flight!
In seems in most launches, it'll go straight up for 50 feet, turn and go horizontal. It then looks like the nose is turning up and is trying to get a little more height. Sometimes it blows the parachute while in the air others on the ground. it's a 50 - 50 proposition.
Heads up!

While this rocket never goes high or far you are completely correct that it is almost always a crap shoot. I've never seen mine go straight up but it has never been horizontal. Usually it ends up at about a 30 degree angle. The real crap shoot with this one is whether or not you get a chute out! The body tube is too small for the provided chute. The last time I launched mine the chute got stuck and the motor mount moved about 0.5" back. I'll most likely retire it rather than fix it. It's just not that great of a performer and is very inconsistent.

 

[shrox]

Which is why I can't understand why it's still in production. Because of this incident, I've quit launching anything that's not a simple 3-4FNC anywhere other than Bunnell. The incident almost turned me off of rocketry for good, and is why I haven't had any real interest in anything more powerful than an E motor.

Shreadvector, I certainly understand the ramifications of the incident, and I was literally terrified to be 'that one guy' who gets rocketry banned. I don't consider myself a careless rocket guy, and do my best to adhere to the NAR code. Even though it's written in a lighthearted manner, I posted it to remind folks that even when their rockets are built well and conditions are seemingly OK, things can still go haywire. Extra caution is never a waste.

Don't write them all off! None of mine are 3FNC.

 

[dave carver]

Don't write them all off! None of mine are 3FNC.

Yeah but I've never heard of one of your designs taking off unpredictably:santa-smile:

 

[Verna]

Don't write them all off! None of mine are 3FNC.

Really! :eyepop: When we have to go to 3FNC I'm out of here.

Seriously, while I understand the point of the post and I congratulate John on handling it all very well, to suggest stopping production of a rocket that has been flying very successfully for 20+ years, is a little over the top. I haven't heard anything in this that leads me to believe there was anything wrong with the design or manufacturing of the kit. Since it had been flown with no problems prior to the bad flight, there has to be something other than a kit flaw at fault in this case.

In my last post I listed several reasons why it might have weather cocked but one I didn't mention before is loose nose weight. If the nose weight broke free at some point during boost and all of it went to one side it might cause what you described.

I consider myself a very average builder and flyer, but I do have a long history with the SR-71. If the Estes kit flys erratically or performs below par, it's either the builder or the launch system. I have built and flown several including clustered and mine have always flown very well for dozens of flights on A's, B's and C's and clustered power of all of those engines.

Having said all that, I would also say that no one should ever fly anything they are not copmpletely comfortable with.

Verna
www.vernarockets.com

 

[loopy]

Awesome shot, Verna!

I have one of these, and I've never had problems with it. Granted, I tend to only fly it on very calm days due to the immense surface area of the wings. Too bad the only post mortem information you can get is the size of the coaches shoes...I coach my sons soccer team, and I can say that I tend to control myself from adverse reactions a bit better than that guy...What's he teaching his players with those actions?

 

[NjCo]

If the Estes kit flys erratically or performs below par, it's either the builder or the launch system.

In my case this rocket was built many years ago and the culprit is most likely weight. It takes some experience to get used to NOT using a lot of glue, especially on something like the SR-71.

 

[The EGE]

The Estes SpaceShipOne also does this sometimes. Hence why I never launch it anymore except when I'm alone.

 

[MarkII]

I consider myself a very average builder and flyer, but I do have a long history with the SR-71. If the Estes kit flys erratically or performs below par, it's either the builder or the launch system. I have built and flown several including clustered and mine have always flown very well for dozens of flights on A's, B's and C's and clustered power of all of those engines.

You? Average? AVERAGE?!? :eyepop: Verna, if your skills are "average," what does that say about mine?? :y: That's a level of "mediocrity" that I hope to achieve someday in my rocketry "career."

Folks, visit this site, and see what I mean:

www.vernarockets.com

MarkII (Ya gotta love those Vipers)

 

[kelltym88]

All I gotta say is, if a soccer ball leaves a field and comes in my direction, do I have the right to pop it? The ignorance of people really makes me upset. While I am not diminishing or making light of what happened, have you ever heard of anyone being hit by a model rocket while under thrust? And if so, what is it like 1 in 10,000,000? I'm sorry, but if it were me, while I would have been apologetic, that does not give that soccer coach the right to do what he did.


But, what is the lesson here? Shread says it best, follow the rules. Make sure you have permission. Or, just don't launch when people are around. I am not condoning illegal activity. I admit that there are occasions when I'll take my son and go over to his school and put a couple up in the air. But, I use very low power motors to keep them real close and real low. Also, there is usually no one around. Shread, disregard this last paragraph.

Dragon, you handled the situation very well, but that guy owes you a rocket. And build another one, but use a D10 or D21.

 

[Verna]

You? Average? AVERAGE?!? :eyepop: Verna, if your skills are "average," what does that say about mine?? :y: That's a level of "mediocrity" that I hope to achieve someday in my rocketry "career."


Thanks for the compliments Mark :blush: but yes, I do consider myself average. None of the stuff we do really requires any special skills. Anyone can do the same things with a little thought and some experience and I really enjoy sharing our experiences with other flyers. It's usually just common sense and not being afraid to crash and burn while you figure something out. It might be a little more expensive that way since I always buy more than 1 of any kit I want to modify as it helps to have spare parts in case things don't go according to Hoyle. Of course, when we are doing R&D, we always fly alone on a private field so if anything does go wrong it's not a problem.

Heck, there are tons of people that do lots more than I can. While I enjoy all forms of rocketry my personal preference within the hobby is mid power and aimed at students. We're not basic, but we're not that complicated either. I guess all I'm saying is don't be afraid to try. Be careful, but not afraid.

:merry-christmas:

Verna
www.vernarockets.com

 

[chanstevens]

I did a quick skim of the reviews of this kit on EMRR (there are several), and most report the weathercocking issue almost exactly as you described.
MarkII

I knew the instant I read "angled the rod a bit into the wind" where the rest of the story was headed. I'm amazed at how often even experienced rocketeers who ought to know better deal with flying in even moderate winds. when the wind is blowing, angle away from the wind! Especially if flying something either 1) overstable or 2) plane-like. Weathercocking doesn't shorten your recovery walk, it shortens your rocket. Instead of going straight up and drifting for 30-60 seconds downwind, you race at full thrust upwind, then drift downwind (if you're lucky enough to deploy a chute and not totally shred it) for 5-10 seconds.

It's totally counterintuitive, but none of us should be angling into the wind, and we should be training others not to as well. I'd also like to see the NAR start to include more information on this in the handbook and occasional safety warnings.

Seriously--is a recovery walk really all that bad? If it is, then maybe rocketry isn't your bag, or at least rocketry on windy days. Think about scrapbooking...

 

[MarkII]

I'm having trouble understanding the logic of this, Chan. I'm with you as far as not angling a weathercock-prone rocket into the wind (it just makes the weathercocking worse, while causing the rocket to waste thrust fighting the headwind), but how does angling it away from the wind help the situation? Won't that also cause a rocket like the SR-71 to readily weathercock, too, but this time fly with the wind? I am just having difficulty visualizing other possible outcomes.

MarkII

 

[Donaldsrockets]

The idea is to launch the rocket against the wind so that when the chute or other recovery device deploys, the rocket will drift back towards the launch area. If angled properly and the right delay is used, this will reduce your recovery walk substantially.

Had the SR-71 been angled against the wind instead of right into it, there is a possibility that it might not have made a beeline for the soccer game in progress.

Nonetheless, the SR-71 is a rocket that I would NOT fly on a breezy day. The Estes Phoenix is another rocket that is also very sensitive to wind and will weathercock severely in breezy conditions.

 

[MarkII]

Don't the two phrases, "angling [the launch rod] against the wind" and "angling...into the wind" mean the same thing?

Nonetheless, the SR-71 is a rocket that I would NOT fly on a breezy day. The Estes Phoenix is another rocket that is also very sensitive to wind and will weathercock severely in breezy conditions.

And the Night Wing, too. Wasn't it another one that would do that?

And in what is perhaps the ultimate irony, the Estes Cruise Missile boosts straight and resists weathercocking. :roll:

MarkII