USLI -- Subscale Launch

We are required to prove our design by building a small scale version of our rocket and launch it. It was a fun weekend putting this little thing together and launching it. This Monday was rather windy in Iowa, but as you can see in the video at the bottom of the post, it performed rather nicely, even in the poor weather conditions. I have no doubt that our full-scale rocket will fly beautifully.

Snazzy way to make a custom nose cone.

Gluing the fins.

Completed rocket.

All systems go.

I Won a Competition!!

Of four people that entered the Iowa State Space Society's model rocket beauty contest, I came out on top, shockingly. Especially considering the fact that I decided to enter and started building only yesterday.

It was modeled after a rocket propelled grenade, and it flew like one, too. I packed the fuselage full of orange chalk-line powder for added effect. It was epic. I'm kind of disappointed that I forgot to bring my camera.

The first prize was a signed copy of "Rocket Boys" by Homer Hickam.

I'll post a picture of the rocket once I get it fixed. It had a rather rough landing...

USLI Testing Proceeding Interestingly

Our USLI project is progressing on schedule. We completed the building and launch of a scale model of our launch vehicle, which went very well. Even in a light breeze it was very stable and flew straight and true. Both flights were very consistent, and had almost identical trajectories. I tried to take pictures, but even on a B6 motor the rocket accelerated out of the picture within at least 0.33 seconds (sports mode on my camera snaps three shots per second).

 

We've also been testing different sizes and shapes of parachutes by dropping the the payload off the top-floor of the atrium in Howe Hall. So far our tests have been inconclusive, but we now know what we need in order to do more thorough testing. But the results we did get look promising. By shortening the lines on one side of the parachute by about an inch, the parachute definitely appears to glide in that direction. I'll post more information when we do more thorough testing.

One of my favorite things about flying in the winter is how rockets tend to "stick" the landing.

The Launch

It was a great day, and lots of fun to see all the rocket designs people came up with. There were a lot of great flights... and a lot of failures too! Our rocket performed well, but its second flight randomly went unstable for some reason. We're not sure what was different about the second flight that resulted in the poorer stability because we did everything exactly the same. As usual, blame it on the wind...

In the middle of the day, they paused the rocket launches to fly a model of the Marston Water Tower on an E9 motor. For some reason the rocket just sat and burned on the pad. I can't imagine that the rocketeer who built it didn't calculate their thrust-to-weight ratio, but you never know. Maybe the launch rod was too tight. Maybe the motor didn't work right.

Thankfully the weather turned out great! It didn't rain, it wasn't very cold, and marvelously the wind stayed in a manageable range.

As fun as the event was, I have to say, it was poorly planned.

For one thing, the objective was to stay inside a launch angle of 20 degrees downrange, at apogee. That is a ridiculous objective, especially since it was 100% based on variables beyond our control. The wind, the random weather-cocking, etc. We didn't even get to choose our own launch angle or put our rocket on the launch pad, so how can we have any impact on which direction the rocket takes off? I think maybe the basis of this idea was that stable rockets are going to straighter than unstable rockets, which is true... but pretty much all of the unstable rockets landed within the acceptable range, because immediately after leaving the launch pad they would spin around and plop down, with little chance to veer out-of-bounds.

Other things: They really needed some sort of loudspeaker setup. I'm sure the guy doing all the announcing can't even talk today. Also, I think that if each team were given a queuing number, the launch would have gone much more efficiently, instead of having each group wait in a long line after each flight.

The altitude tracking setup was a little ridiculous, too. The in-class examples of the triangulation methods were similar to the two-station tracking in The Handbook of Model Rocketry, where there is a baseline between the two trackers, an elevation angle, and an azimuth angle. At the launch, the tracking devices measured only the elevation angle, so we were told to estimate the ground angle with our feet... um... yeah. Highly accurate methodology there. I'm sure lot of people just ended up fudging their data, or making it up completely. We'll be comparing these results to our RockSim simulations, but there really isn't any point when we have a precision of + or - 50% to report!

I really shouldn't complain too loudly though, because the event would probably be a disaster if I were given the task of planning it.

Our rocket being placed on the pad

Long lines

Assorted liftoffs

The water-tower-rocket

Test Launch of AerE 160 Rocket

 

Yesterday afternoon, my group went out to the cross country fields to test our rocket before today's launch (1-4pm). The first flight was rather marginally stable, and it shot off in a random direction with a little wiggle in its trajectory. We then added a little nose weight, and it flew much straighter. The third flight was a little embarrassing because I accidentally loaded a C6-0 motor instead of a C6-5, so the parachute deployed way too early and it ripped off and floated away. The rocket was okay though. It should perform fairly well today. 

Computer Rendering of Next Mach Muncher

...And updated information. I was wrong about the projected speed. If I leave the rocket the way it is (without adding weight to the nose, or payloads), it's predicted to go 1800 ft/s! I don't want it to shred or anything, so I will definitely do something about this.

Revisiting an Old Project...

I'm not giving out too many details just yet, but I will disclose that I'm improving my supersonic design. It should be able to withstand higher airspeeds, so the motor of choice will hopefully be the 137 N-sec G80, the most powerful single use model rocket motor available. If I'm brave, I might even build a payload bay for either an altimeter, an accelerometer, or a camera...

On the simulations, this model reaches a maximum velocity of 1,700 ft/s (almost mach 1.5). Scary, isn't it? It requires VERY different construction and design. My last experience has encouraged me to try again with even more ambition than before.

I'm going to write a new post on supersonic travel soon!

Success! (Sorta)

The good news is that the rocket (I always forget to name them) didn't shred in flight! The bad news is that it wasn't recovered successfully. I think that the ejection charge severed the shock cord and the rocket fell from 4000 feet. The streamer was still in the sky for a very long time, and eventually drifted out of sight.

Did we hear a sonic boom? Well, when it was first launched I was so surprised by the high acceleration that I forgot to listen for one. But when I played the video back, I thought I heard it--two muffled "POP's"--but I'm not sure. If what I'm hearing is the sonic boom, it didn't come exactly .3 seconds after ignition, so I don't think the acceleration was quite as high as the simulation on my computer indicated. The quality of the sound is not very good on YouTube videos. What do you think? Do you hear the sonic boom?

Edit: The sound I am hearing is at about 1:32 in the video.

Supersonic Rocket

I've been working nonstop on my supersonic project, and it's starting to take shape! I've had some great breakthroughs in design and some great ideas on how I can achieve a better flight.

The goal for this project is as follows: To build a rocket that flies faster than the speed of sound and creates an audible sonic boom, built strong enough to withstand such high airspeeds, and be recovered safely after flight.

I've put all my technical ability into this project so that it might survive the high pressures of a supersonic flight.

I am building two of them, and one of them I'm adding a payload bay to so that I can include an altimeter. Then I will be able to determine altitude, velocity, and time to apogee.



Rocket Specs:

Length: 20"
Liftoff mass: 8 oz.
Total impulse: 105 N-sec type "G" motor
Projected altitude: 4,000 ft.
Maximum velocity: 1,300 ft/sec (mach 1.16)

Yesterday I thought of a way I can better my chances of hearing the sonic boom. The reason you don't usually here a boom from a rocket is because the shock wave travels out horizontally on a lateral plane above your head. So my idea is to stand farther back from the rocket and tilt the launch pad a few degrees toward the spectators. I want to aim that shock wave right at us. I'm not sure that would help at all, but I'll try it.

The first launch will be ready anywhere from two weeks to four weeks from now.

Let's pray it holds together!