That sounds like a poorly thought out decision, if thought out at all. Estes and AT BP and composite motors are meant to be handled by children with adult supervision. This sounds like someone in administration who knew nothing about rocketry said:
!!!!!!!!!"
For a while, I led off my workplace fundraising for rocketry club by saying that we were giving teenagers low explosives to load into vehicles with limited steering. You know, hobby rocketry!WHAT? YOU WANT TO GIVE THE CHILDREN GUNPOWDER?!
I think he meant the thrust ring that's part of the motor, notan Estes style engine block.
Beat me to the punch by 30 seconds but here's what I wrote anyway
Interesting... I thought it was fairly common to use thrust ring in an Min rocket. I am using correct terminology right? The 3d printer part that is at the end of the engine? Regardless, while I'm sure it didn't help my situation, the stability margin wasn't an issue(or so I think and that's the general consensus). It was around 3 calibers(with cg overridden), I think the bigger issue was the lack of area. I also used aluminum tape to retain the motor so without the thrust ring something else would need to be done. And finally, there was no engine bulkhead so the thrust ring is kinda important. I will eventually make a floating bulkhead like Adrian A does, but I see that as unnecessary until I throw a loki J motor in there.
I 100% agree, this spring I plan on attending the yearly launch as a RSO so i will have a discussion about this. I know they are having trouble with getting the hybrids from hypertek so they may be open to it. One thing I didn't mention however, is there are certain goals each year. The second year, the challenge is to go Mach 1. On a solid motor this would be really easy. With a hybrid it's a little more difficult especially with a 12k ceiling. So I think that may have something to do with it.That sounds like a poorly thought out decision, if thought out at all. Estes and AT BP and composite motors are meant to be handled by children with adult supervision. This sounds like someone in administration who knew nothing about rocketry said:
WHAT? YOU WANT TO GIVE THE CHILDREN GUNPOWDER?!Of course, I'm jumping to conclusions here, and maybe I'm all wet.
No worries about threadjacking. I think that if the schools fully understood the dangers or lack thereof they wouldn't be to worried about it. But being able to say there is not way this motor can light without special tools etc makes them more willing to throw money at it.
No, dude. this isn't low or mid power where most motors are the same length
I'm sorry, my friend, it's you who've got it all wrong. Because he did not do what you think he did. The ring of material at the aft end of the motor that's a little larger than the motor's nominal diameter - the aft closure or the bit molded into the case of a single use motor, is the "thrust ring" he's talking about. You're talking about an "engine block", which he is not using. He wrote that he used aluminum tape for retention, just as you said one could.
You are right, here is a picture of the configuration. The circled area is where the aluminum tape would go for motor retention.
Agreed, would it be more accurate to say the "simulated" stability margin was 3 calibers? And it didn't carry over into the real world due to boundary layer effects?
Yes. And even more more accurate to say probably due to boundary layer effects.
There are a couple of things that can cause this situation to present itself.
2. Slop in couplers
In one of my screenshots, you can see I had it in percent using my openrocket as default. It was 10.3%, which isnt actually all that low.
I was unaware of these tools in open rocket. I did some analysis of the new fins, they maintain 1 caliber of stability until an angle of attack of 13 or so degrees. It doesn't go negative until 27 degrees. It also helps that I am going to shorten the airframe by 5 or so inches.
I think this may have done me in There was a not so insignificant amount of slop in both couplers. I forgot my painters tape without much thought wrote it off as insignificant.
Not that it matters much in the grand scheme of things, but I modified the design and added a middle support so the tower is actually 6ft. It should help at least a little in the future. It has been updated in OR.
They are now at 9.9ish hopefully that's enough, let me know what you think. I've attached pictures and the OR file.
Yep, sometimes I think it's important for me to learn from my own mistakes. I'm just fortunate I didn't smash up some expensive electronics.
Good to know, makes a lot of sense to.
Inserting, the reason for the length was I wanted to fly a Loki J1026 in it, hence the over building. I also for the cert flight wanted a camera on board BUT didn't want to cut a hole where the bigger motor would be hence the 2 airframes. I'm starting to think that maybe I should give up on wanting to build a rocket that can do both, and make a rocket instead for each. Considering I already have a NC built and a new airframe and fins made it really wouldn't be very difficult. I'll mull over that idea, hopefully you guys have some input.
Here's my conclusion to all of this and what I think may have happened. First I think that the engine may have had a slightly misaligned nozzle, causing a slight amount of off axis thrust. Then once it cleared the tower it pitched slightly. After this maybe some off axis CG stuff happened when the top portion of the rocket shifted due to coupler slop. This is all to say that eventually the rocket one way or another hit an angle of attack of >10 deg. Therefore making it unstable. I think that while the problem is fairly complex the solution is really easy. Bigger fins, and a better friction fit coupler. Like I said I already have a new airframe wrapped and new fins cut. Still need to chamfer them though. Attached is a picture of the OpenRocket to make sure it passes the eye test. And the OR file is also uploaded. One thing I also forgot to mention. There isn't 3 body sections. It's 2 and the top one is really just an extension of the NC.
I wholeheartedly approve.
That does look much better, and I see the static margin is up to about 15%. There's probably a way in OR to specify that you have that straight section of the nose cone, as one piece with the rest, just as you manufactured it. (One can in RS, and I assume one can in OR.) It's not important, but now you know.
To steal @Rschub's analytical summary ... TLAR !
Per Tripoli (and likely NAR has similar wording): "Rocket drifting outside the specified launch range" is one of the grounds for a non-cert flight.
Thanks!
The waiver was 5280ft cylinder, I landed about 6500ft away from the pad. I forget which code it violates but I'm not to bothered. I was going to fly on more L1 motors anyways so it's not a huge deal. Just a little bit of a hassle.
Going outside the FAA waiver cylinder is a party foul.
We all seem rather blase about it, must just be one of those pesky guidelines.
I mainly wanted to clarify why a distance requirement would apply. I admit to being a little too flippant—you’re right the FAA waiver cylinder is important.
happens. I am not picking on you specifically. "It landed outside the waiver" pops up occasionally in launch reports. I would guess that unless it becomes a pattern, things like this are tolerated.
I am not a fan of Will Wheaton and I think his rule was probably plagiarized, but I do try to follow it.
That’s actually a pretty good question. In theory, I suppose that the FAA could pull the waiver of people repeatedly fly outside it. On the other hand, I don’t think I’ve even heard of the FAA taking notice of anyone doing that. And at my current launch site, I don’t know what the waiver radius is let alone how that maps to landmarks on the ground. I suppose that’s a question I should ask at the RSO table at the next launch.Let's just say that it seems the box has corners that are very rounded.... As in, I intended to follow the rules, but
I am involved in a lot of esoteric hobbies. In some, the fear of bodily injury is a strong motivation to follow the rules. Scuba diving, flying, or keeping venomous reptiles, for instance. In others, flouting the rules is a badge of honor, bodily injury be damned, motorcycles spring to mind here.
As a noob, I am just trying to figure out where this hobby is at. So far, my conclusion is that it depends on who is enforcing the rules on any given day. I am curious and a bit nervous because this year I plan to attend a variety of launches outside my local 2 locations.
This seems like an activity where "one size fits all" rules come up short in a fair number of situations. Hopefully, it's all academic for me because I am trying to stay in the exact center of the box.
