Crank - 54mm MD Rocket

Hello All,

Now that I have a decent start on my next project, I figure you'd like to see some pictures.

The project is a convenient 54mm MD rocket. It will be easy to prep and fly, not necessarily 100% optimized for altitude.

My tentative plan is to test fly this rocket this coming weekend on a 38-220 EX motor. This should give me a good idea about performance as well as confirm my recovery scheme. After the test, i hope to enter this rocket in the Mach Madness competition at Red Glare in November with a KBA K700F to about 11,000' at mach 1.2-1.4.

To start, here is a picture of the 3 fin templates taped to my fin material using 2-side scotch tape. The fin material is 0.0625" thick carbon fiber sheet from McMaster-Carr, part number 8194K54.

Once I had the fins marked, i then cut the fins out using my cordless Dremel and a heavy-duty cut-off wheel.

With the fins rough cut, I then used more two-sided tape to stick the fins together to match sand them.

Using my new Ryobi palm sander ($12 at a local refurb outlet!) I match sanded the fins until they are all the same dimensions.

I would prefer to use a table sander, but my current living situations don't permit me to purchase a full shop like i had at my parent's house. I'll have to make due with a Dremel, drill, and palm sander for now!

Now onto the rest of the rocket.

The rocket uses a 48" length of Blue Tube 2.0 from Always Ready Rocketry. The coupler is a Performance Rocketry 8" coupler, with 2" of Quantum Tube glued as a switch band. The nosecone is a Performance Rocketry 5:1 Ogive cone from my Wildman Jr. I parted out.

This kit will also utilize one of the new Aeropack 54mm Minimum Diameter retainers. This is an aluminum bulkhead that will be glued internally and allows me to thread the forward bulkhead of my cases into it. Also, there is a shock cord attachment point on the other side for recovery.

My next step was to cut the tube into two pieces: one is 12" and the other 36". The 36" section allows room for my 54-2550 motor and the motor retainer, plus just enough room to pack a Kevlar shock cord for drogue deployment. I may try to get a streamer in there, but we'll see if I am able to.

The 12" section should have plenty of room for Kevlar cord, a Top Flight Nomex protector, and a 30" PML Main Chute.

The picture here shows approximately how much room I will have. I will be shortening the nosecone shoulder at the line it has drawn on it so that I can mount a transmitter inside, as well as to give me a little more recovery room.

Just to hold you over until my next post (tacking fins on tonight), here is the Rocksim file.

View attachment 54mmRocket.rkt

With the fins and tubes cut, I then marked the tube for the fins.

With the fins marked, I test fit my fin jig on the tube with the fins installed.

With my jig figured out, I scuffed everything up that will eventually be adhered with epoxy (as much as it pained me to scuff those CF fins!

Last but not least, all fins received a small amount of epoxy (4500 Black High Temp from Proline).

I will allow these to set most of the way, and then check alignment again. Following the full cure of this epoxy, they will receive hefty fillets with the same epoxy, and that will be it for reinforcement on these fins.

Judging by the success of others, i should have no issues with regards to keeping these fins on with this filleting method. I will be sure that everything is good and scuffed prior to the fillets, and these babies shouldn't be falling off anytime soon.

Cool project i love MD rockets!

Blue Tube? Good choice...

MasonH said:

Blue Tube? Good choice...

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This is the first time I have used Blue Tube. It seems very robust, sands easily, and is able to be cut with a utility knife. I also like that it's very lightweight.

The one downside to the Blue Tube is that the Aeropack retainer does not fit in the ID of the tube. Bob at Aeropack said he will be putting a disclaimer on his site for this, and is contemplating whether or not he wants to release a Blue Tube specific product.

I checked the fins this morning and they look good. Had some of the cardboard from my fin guides get stuck in the fillets, so tonight I will clean the fillets out, sand everything up again, and then begin the filleting process. Haven't decided yet if I want to use the same high temp Proline epoxy for fillets, or if I should just go with large US Composites with filler.

For 1/16" thick fins, they are already very stiff on the tube.

If you use high temp Pro for fillets your good for mach 2-2.5 without tip to tip.
I did M 2.3 with my 54 minimum project this way.

If using T-T no need for the Pro-Line.

You know where you are headed with this project speed wise so take it from here.....

Personally I would put nice big High Temp fillets & sand a really good airfoil/shape to them & stop there. Saves weight & headache. Unless you are planning on super high thrust/mach flights.

I did weigh the epoxy for each set of fillets to get them the same.

blackjack2564 said:

If you use high temp Pro for fillets your good for mach 2-2.5 without tip to tip.
I did M 2.3 with my 54 minimum project this way.

If using T-T no need for the Pro-Line.

You know where you are headed with this project speed wise so take it from here.....

Personally I would put nice big High Temp fillets & sand a really good airfoil/shape to them & stop there. Saves weight & headache. Unless you are planning on super high thrust/mach flights.

I did weigh the epoxy for each set of fillets to get them the same.

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Thanks for the advice, Jim. I was considering your project when I figured into using only high temp fillets. Your fins were 1/8" G10 vs. my 1/16" CF, but I don't feel there will be much difference in stiffness or possibility for flutter.

I really only need this to withstand the K700F at Red Glare. I can't see pushing it much harder than that anytime soon.

I'll be applying the first fillets this evening.

one thing to keep in mind depending on how high of performance you are wanting out of this is with tip to tip you can use much smaller fillets and get more strength. smaller fillet will have less drag and get you better performance. its a little more work and alot more painful sanding but IMO worth it. i also like to use tip to tip so the rocket is more durable as far as transporting and for hard landings. i can get away with much smaller chutes which means less walking and never have to worry about a fin popping off.

maxvelocity said:

one thing to keep in mind depending on how high of performance you are wanting out of this is with tip to tip you can use much smaller fillets and get more strength. smaller fillet will have less drag and get you better performance. its a little more work and alot more painful sanding but IMO worth it. i also like to use tip to tip so the rocket is more durable as far as transporting and for hard landings. i can get away with much smaller chutes which means less walking and never have to worry about a fin popping off.

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The fins are made out of carbon fiber, and I don't think the FG going all the way to the tip will make the fins much more rigid than large fillets. Because they are already very strong and have little flex, all that is needed is to make sure they are rigidly attached to the tube.

Essentially, the mass of the glass from fillet to fin tip, and from fillet to fillet on the body tube will be added drag and weight without much return on strength.

To me, T2T is just not worth the added work with finishing when fillets will be plenty strong.

Here is the first set of fins to receive fillets. i scuffed up the epoxy that had cured really well with 100 grit paper, and then laid down the masking tape boundaries. You can also see the remains of the cardboard that I didn't want to sand completely away and risk cracking the somewhat fragile fins.

With everything scuffed up, it was time to lay in the epoxy fillets. The high-temp pro-line epoxy was mixed up and then placed in the fillets. I then used a plastic spoon to spread the epoxy out evenly until it was a respectable fillet.

Once the epoxy is somewhat cured, I'll pull the masking tape off and scrape any unwanted epoxy off.

Rinse and repeat this 2 more times, and then hopefully this thing will be ready for Saturday!

As promised, here is the first set of fillets with the tape removed.

Fillets look nice, smooth, and consistent. Now it's time to move on to the next set...

On a side note, here is the altimeter bay getting the sled glued to the guide tubes.

Guide tubes are 9/32" ID aluminum tubes bought at the local True Value. The board is 1/8" ply. Sled will have enough room for an ARTS or ARTS2, with a battery holder and rotary switch. You can see those holes are marked, I will drill them once this is cured.

2nd set of fillets curing...

The rocket is essentially built. Things left to do:

• Machine down Aeropack shock cord mount
• Sand fillets so they are totally smooth
• Finish altimeter bay (just need to drill some holes and mount terminal blocks)
• Secure altimeter bay to main chute tube
• Cover bare tube with Minwax to seal it
• shear pin the nosecone
• Adjust fits of coupler and nose shoulder

Following all of that, it will be prep and fly time. I didn't get out to MDRA this past weekend for a test flight, so it appears the first flight will be the K700F at Red Glare. Hoping those fins stay on!

I will try to post some pictures tonight.

Dan, great build! I've been quietly watching...as I typically do.

It looks like Red Glare is scheduled later than originally thought...any chance you're going to still do a test flight, or are you just going to hit it with the K700? Regardless, I love Kosdon Fast propellant (even if it is the stuff that Aerotech made:wink.

Great job and good luck with the flight(s)!

-Eric-

Eric
If you like Kosdon fast burn you might want to try and watch my flight at MWP. I have a Kosdon 38mm J1500 burning it in a Shadow Aero Raven. Dave says its like pulling the trigger and its gone.
Gary

If you like Kosdon fast burn you might want to try and watch my flight at MWP. I have a Kosdon 38mm J1500 burning it in a Shadow Aero Raven. Dave says its like pulling the trigger and its gone.

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Gary, sweet! I thought you were going to sell that hardware & load to me:wink:. I'll be watching for the flight....and watching for the for sale sign on the hardware post flight:wink:!

-Eric-

Eric
The Hardwear is on lone form Dave T from Shadow Aero. So I must get it back. Its one of the only one he has left from Frank.
See Ya

ECayemberg said:

It looks like Red Glare is scheduled later than originally thought...any chance you're going to still do a test flight, or are you just going to hit it with the K700? Regardless, I love Kosdon Fast propellant (even if it is the stuff that Aerotech made:wink.
-Eric-

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Eric - Looking like no chance for a test flight. Odds are if the weather cooperates at Red Glare, I will hit it with the K700F right off the bat.

A few design changes are underway - most importantly I will be doing a tip to tip on the fins with 5.7oz Carbon. I have some cloth from a while ago that I figure I may as well put to good use. It will also make me feel much better about the K700 flight.

Today I was able to get access to my father's lathe and turned down the Aeropack motor retainer. It now slides in the Blue Tube 2.0 airframe.

Picture 1 is of the retainer chucked up in the lathe.

Picture 2 is of the retainer machined to a snug fit in the airframe.

Picture 3 is of all of the hardware on the retainer for shock cord mounting. This eyebolt will be glued into the retainer with JB Weld when I am ready to install it in the rocket.

Needless to say, I miss having access to my dad's shop!

patelldp said:

Needless to say, I miss having access to my dad's shop!

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I know the feeling.