NASA Students

hey guys,
We posted on here when we started, and now we have recieved help so far, but we are not done yet. We need to launch in a month, and are far from complete. We have made our own carbon fiber tubes, made the nosecone, made our electronics sled, made our fins, and ordered all of our electronics. We are wondering if anyone knows about how we should get our center of pressure back. We are trying not to add more weight to the rocket, but if we have to, we will, the fins are made, but i guess they could be changed. We havent decided on the engine, but it will either be an AMW K600, or a L777 ww. If you could look over this RockSim file and tell us what you think, we would greatly appreciate it.

I don't see why you need any change to the CP. It's perfectly stable by my sims, and should fly just fine. I would reevaluate the motor choice though - it's a bit slow off the pad on those motors. It would probably be fine, but it'd have a little better speed off the rod with something like an L1060GG or an L1080BB.

hey, sorry but the RockSim is not up to date. We have an updated one on the other computer, that i will post tomorrow, as soon as i can. We were also wondering about the number of Calipers. What is too much. We are at 2.5 ish, is this too many?

2.5 calibers is not a problem at all. The rocket in my avatar has 6, and it flies just fine. However, with the motor you have chosen, it may be prone to weathercocking unless it is significantly lighter than the file you posted. I would still reccomend one of the faster motors. Plus, green gorilla is cool

I think the velocity at the end of the launch guide was like 69 f/s. Also what kind of launch rail and lugs would you suggest?

Guys, if the tube isn't sloted yet just move the fins forward say half a caliper (2.75").

Like this.

That brings the static margin to 1.89.

Don't use launch lugs get a set of rail guides.

Find out what size rail they'll be using in Huntsville.

The rocksim file is too big to attach, but we will try to figure something out. Sandman,why did we make the nosecone longer?

Partially looks I would guess - I personally like the looks better with about a 4 to 1 ogive, or even a 5 to 1 (although a 5 to 1 is getting a bit long). And definitely use rail guides if you aren't already - they are VASTLY superior to rods.

Oh - and try zipping the rocksim file. That should shrink it enough to attach.

Here is the compressed file of the Rocksim of our rocket. Any comments on the rocket would be greatly appreciated.

It looks good. I would still reccomend the L1060GG, but now it has nothing to do with stability. The WW motor will still keep it stable, but I just like GG. Looks like a great design, though, and do you have any pics?

Why did we make the nose cone longer?

No reason just looks. I was just working with the piece of foam you guys gave me.

Actually this is closer to the shape I made.

It's conical but then it transitions into an ogine.

I dont have any on this computer, but we will take some tomorrow, and i will load them on here, we are really excited, we are faring the couplers tomorrow and should be ready for the fin can by tuesday!! Should we do anything to the shape of the fins like taper or anything? Ill talk to all ya tomorrow though. Night

If you can, bevel the fins leading and trailing edges to reduce drag. However, this is not a big deal, and will not drastically affect flight.

What thickness fins did you finally decide on? I don't remember.

Whatever you do to the fins just do it for looks. It won't affect performance that much but a tapered diamond profile sure would look pretty!

But it's really hard to do consistantly.

You could, if you had the time, make a cutting jig and cut it on the band saw.

If you do a knife edge be warned, you'll have to glass the fins 'cause the plyweood will be really fragile at the edges.

Morning guys, the fin size we went with was half inch ply. The root cord lenght was 8", the tip cord length was 4", and the semi span was 6". We modeled the fins after the Nike series by NASA. We are glad to see that people are willing to help high school students. Thanks for the help, and we will load pictures tonight. We will also let you know how we did, with pics tonight. The companies, we can give you all the details on them also tonight.