Just passing along some photos and videos of my current projects.
Optimus is the humanoid looking rocket with the odd body tube. To make
him we sanded polystyrene into the correct shape and then laid it up
with fiberglass. I did one coat heavy and one coat medium weave
fiberglass. The head is also polystyrene with Bondo and resin on it.
The fins are aircraft plywood with carbon fiber on them and fitted into
slots in the body tube (Also used many layers and fillets of epoxy!).
After the layups we vacuum bagged each component. The inner tube is 2
layers of medium fiberglass. All that he needs is a parachute and en
engine hook.
The most exciting part of this email is the Vertigo prototype. This
is a scale model of my current high power project fixed in recovery
mode. The full-scale
high powered rocket version will reach an apogee of about 3500ft.
The prototype began as two fiberglass tubes, both 3 layers of heavy
weave glass. After they dried, I used a dremel tool to cut the bigger
tube into 5 equal sized blades. I then drilled a hole off center at one
end of each blade and fixed an L-joint to it. I attached each of the
blades at equidistant angle to provide radially symmetric mass
distribution. After each blade was attached we used a 5-minute epoxy to
secure the connections. A plug for the top was made of polystyrene and
epoxied in. The nosecone was sanded out of polystyrene and filled with
lead shot to provide weight and bring the center of mass well below the
blades.
The drop tests went much better than expected. The auto-rotation
recovery method we are using require sufficient height to stabilize and
then initiate, so ideally a higher drop site would have been used. In
the videos you can see the prototype stabilize and begin spinning. Very
exciting for me, I were not sure how well that design would work. I
will now begin constructed a 2 meter long and 9lb version of this that
has spring loaded blades and a GPS/IMU unit for deployment. Hopefully I will launch with a 54mm J-class impulse motor.
Hello. Just wanted to let everyone know that I am beginning a huge project for the semester. High powered rockets are fun to build and fly. The rocket science behind even the simplest of models can be staggering when it comes to optimizing performance, but I wanted a bigger challenge. What if I could make a rocket that is about 10lbs... with no parachute!!!!
It's possible! The recovery system is called auto-rotation. The process of auto-rotation is used by helicopters already to safely land when their engine dies. The spinning blades provide enough drag to slow the descent velocity to a safe speed. Theoretically it sounds simple, but implementing this on a rocket is going to be a long process.
I started with a simple design using a triangular body tube that unfolds into 3 airfoils. But, after consulting with an expert, decided to go with an 8-blade system that out from a cylindrical body tube. The motor we are currently considering is a Cesaroni Pro-54 or Pro-38, impulse class J. This should provide plenty of thrust for our heavy rocket, but not send it to a soaring apogee or transonic speeds.
As we prototype and design parts for this rocket, I will post them on the blog. This project will certainly test feline advancement in aeronautics!
Went out to Hearne, Texas this weekend for a Tripoli high powered launch. My monkey's rocketry group was having a tournament. We watched a lot of small rockets use mid-power motors to reach 3500 feet, which was pretty exciting. It was very windy, so most of the rockets were never seem again. This also marked the weekend of trying to get my level 1 high powered certification.
The menacing Zombie took the launch pad armed with a H400 Vmax engine and kicked off the pad with no problems. The rocket easily went 3000 feet and the ejection charge fired of the nosecone no problem. The descent velocity was way too high and as it came closer, we realized the parachute was tangled. The Zombie tumbled down into the ground, but none of the components broke!! The fin fillets, the epoxy keeping the fins in the body tube, came off sadly. This meant that the zombie was not "flyable" on recovery, so I couldn't receive my L1 certification.
The range safety officer, RSO, was very kind and allowed to to go re-epoxy my fins on. After the fins had set, I threw the Cesaroni H125 Classic in the Zombie and it took the pad again. This time, I had used a different parachute packing technique, showed to me by a very kind group of fellow rocketeers I had met there. Instead of wrapping the parachute in the shroud lines, as is commonly done with model rockets, you fold the shroud lines into the canopy and roll it up. This may seem like a subtle difference, but it keeps the shroud lines from becoming tangled.
All was set for try number two, and the RSO counted down and hit the launch button. This engine was very different than the Vmax (as described in a previous post), but the rocket still flew straight. Until the phenomena of fin flutter kicked in. As a rockets speed increases, the amount of turbulent force on the fins increases drastically. At a certain point in it's trajectory, the flutter forces overcame the new epoxy fillets and all the fins flew out of the body tube. The rocket immediately lost its speed and started tumbling down to the ground. This was concerning, because the rocket had a specific delay charge that anticipated reaching simulated apogee.
The rocket tumbled down to about 15 feet above the ground before the ejection charge went off and the parachute slowed the rocket. If it had happened one or two seconds later, the Zombie may never have flown again. Luckily, all three of the fins were recovered and the body tube was unscathed. For the next launch, I plan on using a much stronger resin with flecked cotton to increase its strength. I will also use a composite material on the joints to make sure that the fins are now permanently attached.
The Zombie will rise again and I will be sure to pack the parachute right and use it to get my level 1 and level 2 certifications.
Here's a video of the rocket taking off the pad. I wasn't prepared for just how fast this take-off was going to be!
Good afternoon!
In my last post I was complaining about some mistakes I made making my rocket. It mainly had to do with the weight causing it to take a high initial thrust motor to reach stable velocity before leaving the launch rail. Good News!
The launch was canceled due to rain. I normally would be very sad, except that provided me with the opportunity to order an H400 VMAX motor, which will allow my rocket to reach stable velocity at around 14 inches. The duration of thrust is about .68 seconds, which is about half the old motor. This should allow my certification flight to go well! An added bonus, I was able to spend the Saturday laying on my balcony penthouse in the rain.
I also took advantage of this delay by ordering a sonic locator for my rocket. I make millions in the fish markets every year, but I am still not one for wasting a 200 dollar rocket. The estimated apogee, furthest distance from the earth, is around 3000 feet. Then the parachute deploys and it drifts safely back to earth. The sonic locator will activate at apogee (light sensor) and will screech loudly until the battery is taken out. Hopefully this will aid in recovery if the rocket were to drift too far from the launch site. Felines are not ones for wandering around unknown brush looking for rockets.
This is what the sonic locator looks like!
Hopefully the Zombie can withstand the forces that this motor will put on it! a great test for the rocket to see if it can withstand the J motor I am going to fly it with next. I already bought the 6-grain case. Here's a comparison of the 6-grain case with the 2-grain case the H400 is in.
The second from the left is the 2-grain case. The second from the right is the 6-grain ca
Hopefully that increased force doesn't do this to the Zombie...
The motor used in the video above is the lower impulse motor that I'm going to use first for my certification flight.
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