Der Mad Max - The Estes Design on Steroids

[EeebeeE]

Who make the cone that will work for this see estes is out of stock for a kit and don't sell the cone

My MDRM had worn out so I used its nose cone.

 

[EeebeeE]

Flying season is approaching so I am thinking about recovery for all my rockets including this one. My hope is to have a couple sleds that will be interchangeable between rockets so I took a little time to design recovery systems in individual rockets that could accept the same sled. Since this is to be a machbuster, I want to use my Raven 3 altimeter which can give me accurate speeds above Mach 1. I had planned to use the raven in a couple other rockets so the slide is designed to fit into those as well.

The Der Mad Max needs to have a chute cannon in the nose cone for DD. The last time I tried a cannon, I placed the electronics in the nose and came up with a very complicated system where wires ran everywhere and the cannon was removable (because it had to be). I did not want to deal with that this time. So the challenge of simplification led me to several thoughts.

Then I stumbled on an idea. What if the cannon blew out the AV Bay as well as the chute? The benefits became very clear. The cannon could then be permantently mounted. The chute would attach directly to the forward section of the AV Bay. THe aft end of the AVBay could be connected to an eyebolt at the base of the nose cone. A second eyebolt would connect the nose cone to the booster section. The electronics bay could be more easily vented by gluing a section of motor tube around the coupler tube that makes up the AV Bay. An added plis is that the plastic nose cone is not more structurally supported so it should better withstand mach speeds.

First I made the cannon section using Blue Tube and a couple CR's. A bulkhead was glued onto the forward end of the cannon to concentrate the blast. While the glue dried on the cannon, I added a ring around the coupler tube to keep it from sliding into the cannon


I dry fit the AV Bay into the cannon.


I glued the cannon into the nose cone. As that set, I drilled holes into the bulkheads as well as drilled vent holes into the airframe section of the AV Bay. That section will sit aft of the Noase cone CRso any vents from the rocket airframe will also vent air pressure from the AV bay.

Here is the completed AAV Bay and you can see the location of the vent holes.


And this is how everything fits into the nose cone.

 

[BDB]

Very interesting. But why does this thing need a chute cannon? Is it just due to the fact that the airframe:nose cone ratio is smaller than usual?

 

[EeebeeE]

Very interesting. But why does this thing need a chute cannon? Is it just due to the fact that the airframe:nose cone ratio is smaller than usual?

Yes. The airframe is only 20.5" long. If you cut it in two and added an 8" long AV Bay in a coupler tube, you could only get a 2 grain motor in the thing. As it is set up now, I can get a 5-grain motor in it.

 

[EeebeeE]

Well, I'd like to report a great flight and a great video. Alas...that wasn't the case. First the battery on my camera died, so no video. Next, the EggTimer then grounded as I was trying to feed the wires for the twist and tuck switch through the side of the airframe. The main charge blew and gave me a real nice battle scar on my finger. Last time I use an Egg Timer. Finally got the rocket to the pad. A CTI K1720 in an AMW case. The case failed. The rocket blew into hundreds of tiny pieces. Lost was the Eggtimer. A Jolly Logic Altimeter 2 (second and last Jolly logic altimeter I buy...not that I don't like them...just that they are a curse to me. The first Jolly Logic was lost in a CATO. This one was as well), and a Beeline tracker. The beeline was in a capsule right next to the motor, so I am pretty sure that there isn't a piece bigger than 1/8" square of it. I will say that my fincan survived largely intact. There are pieces I can salvage.

Live by the extremes. Die by the extremes. Couldn't help myself...I got an AMW FG Max. Here we go again.

 

[BDB]

Wow! That sucks. This is such a masochistic hobby.

 

[EeebeeE]

Wow! That sucks. This is such a masochistic hobby.

It is. But I still have a fin can!

 

[patelldp]

How did the motor blow up, can you post pictures of the case?

 

[EeebeeE]

It was a defective snap ring case. The channel in the snap ring was too deep, weakening the wall in the area it was deepest. Couldn't handle the pressure. It was a borrowed case so its owner is getting a new one under warranty. I do not have photos. AMW sold me the motor and took care of me in another way, which was more than enough compensation. Robert and Gloria are very good people.

 

[patelldp]

It was a defective snap ring case. The channel in the snap ring was too deep, weakening the wall in the area it was deepest. Couldn't handle the pressure. It was a borrowed case so its owner is getting a new one under warranty. I do not have photos. AMW sold me the motor and took care of me in another way, which was more than enough compensation. Robert and Gloria are very good people.

Are you sure? Did you measure the remaining thickness on the case? I doubt it was a defective case, probably a defective load causing the case to fail as designed.

 

[EeebeeE]

I am more inclined to go with AMW's POV. After all, they designed the cases and spec'ed the loads that go into them.