MK82 High Drag bomb rocket

ChrisAttebery

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Before I got out of rocketry 13 years ago I had designed a Mk82 "Snake Eye" bomb type rocket with petal type air brakes. I started a thread on Rocketry Online about it but never built mine. Someone there had actually built one about BT60 sized. Your thread and the one on the umbrella chute got me thinking about it again. Over the weekend we attended our first launch with the kids at Moffett field. Afterwards we were able to take a tour of a P3 Orion and they had the sonobouys on display. They also use a petal type air brakes. I explained how it worked to the kids and told them about my rocket idea and it got the creative juices flowing again. I've got it all drawn up in Open Rocket. I just need to order the parts.

Here's a picture of what I am thinking about:

MK-82Snake-eyeBombs.JPG

This is what I came up with. The motor mount tube will be the main structure of the rocket. I'll use LOC or some other heavyweight 24mm tube. The outer shell will be made from BT-80 and I'll use a long BT-80 nose cone. The front 6" of the body tube will be attached to the nose cone. The forward section of the rocket will slide front to back on a coupler that is attached to the motor mount. The rear 12" will be cut into 4 sections and then a fin will be glued to the edge of each section. These sections will be hinged into a thick balsa centering ring at the rear. The front edges will have a short segment of coupler glued to them. In flight these segments will be captured inside the back edge of the front section of tubing. When the ejection charge goes off it will push the forward section forward and the rear segments will be free to open up. The four segments will be kept from opening too far by lengths of kevlar twine.

SnakeEye2.jpg

SnakeEye.jpg
 

Ropes4u

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That is a beautiful rocket and I wish you the best.


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BABAR

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Rex R

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the Estes 'Sky Winder' does much the same thing...I would suggest some form of spring/elastic to ensure the fins 'pop', and some form of cushion/buffer in your Kevlar to slow deployment as the fins reach full deploy.
Re: paint/landing
no they were not worried about the paint after they were dropped from the aircraft...in storage was a different matter :).
Rex
 

ChrisAttebery

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I ordered all of the off the shelf parts I need today. I ordered some reloads at the same time so it's going to be a couple weeks before they show up. That should give me plenty of time to design the hinges and work out the other mechanics. I think I'll build a torsion spring into the hinges to help snap them open. It looks like McMaster has a good selection. I can probably get them at one of the local hardware stores too.
 

ChrisAttebery

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I got all of the laser cut parts designed today and sent the file off for a quote. Hopefully I'll didn't miss anything and I'll have some parts to work with soon.

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ChrisAttebery

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I finally got the laser cut parts yesterday. The vendor had to wait for some 3/32" ply to come in with a large order. All of the parts look great and fit as expected. I started assembling the hinge assembly first. The rings are notched for the hinge plates. For now I tack glued all of the joints with thick CA.

The rear body tube will be slotted in 4 places around the circumference. I will leave 1/4" tabs front and rear to hold the sections together.
The outer rings are cut 80% of the way through. Once they are glued in place I will finish cutting them apart.

IMG_1484.jpg

IMG_1485.jpg
 

Ropes4u

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That's a beautiful looking part


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ChrisAttebery

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Thanks. I spent a couple nights working on the CAD files trying to make sure I didn't miss anything. It's been a long couple weeks waiting for the parts to arrive so I could verify that it all fits together. This is by far the most complicated build I've ever done.


That's a beautiful looking part
 

ChrisAttebery

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It's been a while since I updated this thread. I made a fin guide in CAD and marked the location of the fins and the launch lug. The plan is to slot the tube to within 1/2" of each end where the petals will split apart. Well, I marked the tube and reminded myself not to cut the launch lug mark, but after I cut 2 slots I realized that I cut along the lug mark anyway. :facepalm: Not my finest work.

I was able to pick up another BT-80 today so I'll try to pick up this build soon. Mother's day is this weekend I doubt I'll make any progress in the next couple days.
 

CRC

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very cool looking & sounding sofar, keep us updated.
 

K'Tesh

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Before I got out of rocketry 13 years ago I had designed a Mk82 "Snake Eye" bomb type rocket with petal type air brakes. I started a thread on Rocketry Online about it but never built mine. Someone there had actually built one about BT60 sized. Your thread and the one on the umbrella chute got me thinking about it again.

Was that my thread about a similar type of recovery for my Velociraptor downscale that got you thinking about this (and the one with the umbrella chute)? Or another thread that I somehow missed and need to see?
 

wagondriver42

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I can not wait to see this completed. Having been in the Air Force, I love any rocket that resembles a missile/military rocket/or bomb. But this is beyond freakin cool.
 

ChrisAttebery

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Was that my thread about a similar type of recovery for my Velociraptor downscale that got you thinking about this (and the one with the umbrella chute)? Or another thread that I somehow missed and need to see?

No, it was on Rocketry Online around 1999.



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ChrisAttebery

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Thanks for all of your enthusiasm guys. Hopefully I can get this thing completed soon.


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ChrisAttebery

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I let this build simmer on the back burner for a couple months while I worked on my LOC Door Knob and thought over the build. Yesterday I made a bunch of progress:

IMG_2231.JPG

IMG_2246.JPG

IMG_2247.JPG

I still need to add some kind of spring to the hinges, work on the kevlar stop straps, and do a couple ground tests but the pictures get the point across.
 

ThirstyBarbarian

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Wow! That is really cool! Are the air brakes the only recovery device, or is there some other kind of chute or streamer involved?
 

ChrisAttebery

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Thanks guys. This is the only recovery device. I may have to add clear plastic between the petals to get an acceptable decent rate.


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Screaminhelo

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This is beyond awesome! Perhaps you could introduce some twist for a helicopter recovery?

I imagine that this thing is going to want to autorotate to some degree anyway. Since this certainly deserves continued development, I propose that the root end of the petal be 1/4 circumference of the BT and just long enough for the mounting structure while the rest of the span be about 2/3 circumference. The trailing edge should tuck under it's neighbor without any fuss. Of course, if your goal is to mimic a Mk 82 mechanism as closely as possible, disregard what I just suggested. I am a rotor head and my mind tends to go that way.
 
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