[Motor Purchased] 5 inch diameter rocket and a CTI O3400.

[CarVac]

Did your motor CATO or did the rocket shred?

It didn't shred but the nosecone came off at Mach 3.7, and the shock cord snapped. Being a flying motor case design, and the other components of the booster being stronger than the motor case, the case got badly damaged upon impact.

 

[ColumbiaNX01]

Oh yikes!! was it the N5800?

 

[CarVac]

That's the one.

 

[JimJarvis50]

That's the one.

I pushed the button!

Jim

 

[jpummil]

I pushed the button!

Jim

Did you let out a diabolical "Muahahaha" as you did so?
:grin:

 

[JimJarvis50]

Did you let out a diabolical "Muahahaha" as you did so?
:grin:

That would have been wrong. I suppose at this point I could reveal what I was thinking, but didn't vocalize.

As I recall, it was "Muahaha.crap". Not positive about the second ha, though.

Jim

 

[ColumbiaNX01]

I didnt realize the motor case was that big!!!!!!!!!!!!!!!

 

[CarVac]

I didnt realize the motor case was that big!!!!!!!!!!!!!!!

It certainly is enormous.

Oddly, once you load it, it no longer seems quite so large anymore.

 

[CCotner]

Did your motor CATO or did the rocket shred?

Technically, neither. The nozzle was damaged, and the rocket design was vulnerable to a type of 'coning' that was perfectly excited by the damage. The rocket basically spun out, but it's flat spin was so fast the centripetal acceleration tore the shear pins and it separated. It would have been a full recovery, but the kevlar strap tore a few seconds later (the delay is very apparent on data traces of both acceleration (all three axes) but also the pressure inside the nosecone) for reasons I'm not completely clear on. The booster (fincan, motor case, and an aluminum airframe screwed onto the front of the motor via an extra-long retaining ring) lakestaked from ~10kft agl. An unfortunate day all around.

 

[CCotner]

That would have been wrong. I suppose at this point I could reveal what I was thinking, but didn't vocalize.

As I recall, it was "Muahaha.crap". Not positive about the second ha, though.

Jim

AHAHAHAHAHAHAHA

oddly, that about mirrors what was going through my mind as I crouched next to you snapping photos. =p

 

[ColumbiaNX01]

If my rocket ends up being around 25 pounds with RasAero it says that rocket with a N5800 will go 23,000 roughly. I see on the motor list in that program there is not an O3400 option. Both being in the same case, but the O has a longer burn the altitude will be higher but I believe not by much, but some. So my question is will black powder fire at 25,000 effectivily to "pop" the rocket apart at apogee. Obviuosly the higher you go the less oxygen, but I did not know how affected the black powder will be at that altitude.

 

[CarVac]

If my rocket ends up being around 25 pounds with RasAero it says that rocket with a N5800 will go 23,000 roughly. I see on the motor list in that program there is not an O3400 option. Both being in the same case, but the O has a longer burn the altitude will be higher but I believe not by much, but some. So my question is will black powder fire at 25,000 effectivily to "pop" the rocket apart at apogee. Obviuosly the higher you go the less oxygen, but I did not know how affected the black powder will be at that altitude.

You can add motor files yourself by inserting the rasp file contents into the .eng file in the RASAero directory in my documents.

 

[ColumbiaNX01]

how effective will black Powder be at 25,000 feet compared to lets say 5,000 feet? At 25,000 feet should I be thinking of a CO2 ejection charge?

 

[COrocket]

how effective will black Powder be at 25,000 feet compared to lets say 5,000 feet? At 25,000 feet should I be thinking of a CO2 ejection charge?

I've used BP up to around 22,600 MSL and it worked (although i couldn't visually track it to see how well it worked - at least well enough to separate the airframe) It was stuffed in a nitrile glove finger and zip tied shut. Other people have used BP packed in surgical tubing for high altitude flights. Personally I wouldn't fly much higher without modifying my technique or moving to CO2.

 

[JimJarvis50]

how effective will black Powder be at 25,000 feet compared to lets say 5,000 feet? At 25,000 feet should I be thinking of a CO2 ejection charge?

I wrote an article on high altitude deployment, which uses BP and which i have used successfully above 100K. The article is located here (although you don't really need to read it unless you're just curious).

https://www.rocketryfiles.com/

The conclusion you would come away with is that if you reasonably contain the black powder in something with hard walls and covered with several layers of tape, as an example, you would be fine at 25K and likely much higher. However, it is my opinion that using something that is not so contained (a latex glove or surgical tubing as examples, you would need to begin compensating for unburned powder by increasing the amount of BP that you use.

At 100K, though, you have to do a little more than a hard-walled container.

Jim

 

[ColumbiaNX01]

Ordered and received my 1 gallon kit of Aeropoxy for this project. Got the stuff from Kent Burnett at Giant Leap. Kent is a joy to work with and has many great ideas!!!!!!!!!!!!!



Andrew Lathrop

View attachment 161140

 

[MarkH]

Cool! That should last a while. I've gone through about 1 quart of that stuff on 3 different 4 inch rockets, wrapping the tubes with CF or FG, and bagging the fin can and just had to order another quart kit.

Ordered and received my 1 gallon kit of Aeropoxy for this project. Got the stuff from Kent Burnett at Giant Leap. Kent is a joy to work with and has many great ideas!!!!!!!!!!!!!



Andrew Lathrop

View attachment 161140

 

[ColumbiaNX01]

Got a question folks. I am wondering what kind of rail buttons to install. My gut feeling is to put on the standard buttons for a 1 inch rail that we all normally use. But should I go with the bigger buttons, the ones to fit a 2 inch rail? Remember this project will weigh around 50-60 pounds when finished. Most of that is motor.

 

[CarVac]

No buttons. Tower!

EDIT: Also, the motor is "only" 33 pounds. Half of your rocket will be motor.

 

[bobkrech]

That's too heavy for a 1010 rail.

Minimum is 1515 (1.5") rail with 5/16" slot and a really stiff launch pad fastened to the ground.

Bob

 

[FredA]

That's too heavy for a 1010 rail.

Sorry Bob -- rarely disagree with you , but not really.
Have flown 100# rockets using 1010.

Weight isn't an issue -- the rail isn't holding the weight.
The PAD holds the weight.

All rockets DO BENIFIT from a supported rail -- one tied to a tower and held stiff.
Rail whip is real and COULD be an issue with this rocket.
If your pad only holds the rail at the bottom, you might want to move to a stiffer rail as in 1515.

But no need to move to a larger rail just due to weight.

 

[ColumbiaNX01]

My understanding is now that the 1010 buttons will hold. but the caution is the rail may whip. Then next thing is using a 1515 button. The ultimate would be a tower. The 1010 would have least drag. This rocket sims at mach 2.2, but those are generous numbers. At those speeds the 1515 button will melt off more correct? The 1010 are smaller and that equals less drag.

 

[JimJarvis50]

My understanding is now that the 1010 buttons will hold. but the caution is the rail may whip. Then next thing is using a 1515 button. The ultimate would be a tower. The 1010 would have least drag. This rocket sims at mach 2.2, but those are generous numbers. At those speeds the 1515 button will melt off more correct? The 1010 are smaller and that equals less drag.

The only thing I don't see in your summary is the idea of the supported rail (as FredA mentioned). Our club has a 1010 rail with a 1.5" (or maybe 2"?) pipe supporting its entire length. I would much rather use that rail for the flight you're considering than an unsupported 1515 rail.

The ultimate is not necessarily a tower (i.e., something that doesn't use buttons, just so our terminology is straight). Most towers I see are too short.

Jim

 

[bobkrech]

I made a poor choice of words. I was expressing my concern by the high (1000 pound) thrust, and therefore the torque that can be generated by the O-motor, both to the pad and the rail. The pad can be restrained by staking however the rail issue is stiffness, and a lack of stiffness can create rail whip exactly as you point out which is the reason for my preference of a 1515 rail at minimum.

As you and Carlo point out, attaching the rail to a tower mitigates the torque, but in my read of the posters statement I didn't believe a tower was available, and if not, I would recommend using a 1515 rail over a 1010 for an O motor.

Bob

 

[CarVac]

My understanding is now that the 1010 buttons will hold. but the caution is the rail may whip. Then next thing is using a 1515 button. The ultimate would be a tower. The 1010 would have least drag. This rocket sims at mach 2.2, but those are generous numbers. At those speeds the 1515 button will melt off more correct? The 1010 are smaller and that equals less drag.

I don't think the size of the button affects heating, though it does affect drag.

If you can you may want to get a short rod of PEEK or PEI or other high strength, high temperature plastic and machine your own buttons. Or commission someone from the forum to do that for you... Perhaps SCP can do a special version of their airfoil guides for you.

 

[ColumbiaNX01]

Go here this is my clubs website and we have a tab on there for my project. I know the pics are on here, but this is a place where all the pics are together.

https://tulsarocketry.org/projects/member-projects/

 

[blackjack2564]

FYI; There are several sizes of 1010 buttons, small, streamlined,etc. The "standard" full size 1010 button will in fact, fit a 1515 rail. I use them on 15 15 rails all the time. Especially when there is a wait at the pads due to the 1010's being full.....I just go out to the far pads instead of waiting for the next rack.

BUT.. odds are what ever you use....they will be shot after flight. After my N-10,000 & N-5800 flights, there was nothing usable of the the buttons left. They were flat sided from friction in all 3 cases.

 

[ColumbiaNX01]

Crazyjim: I planed on using the stream lined 1515 raid buttons from SC Precision.

 

[CCotner]

my normal response would be something like TOWWWEERRRRRRRRR but since it's non-MD I suppose absolute altitude isn't the goal. I'm sure a 1515 rail, maybe a stiffened 1515 rail, would be sufficient.

 

[ColumbiaNX01]

I am launching in Argoina. I have talked to Bob Brown they have a 1515 rail that is reinforced to 2inch X 3inch pipe on a trailer.