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Ladyrobin 2.0

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n3tjm

Papa Elf
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I have some larger I motors in my range box, and the only rocket I have that I could fly them in is my Megablast, but that rocket is worn and tired, and I am not sure it wont buckle with the power of an I800 or I540. So I was on a the market for a new 4” rocket that can take the high thrust I motors and stay within the flying limits of the Amesbury Field. At first I was considering an Extreme Wildman, but I was not sure how much that rocket weighed, and I could not find a rocksim file. After a few calls and e-mails and no answers to my questions, so I decided to go with something else.
Since my Ladyrobin crashed a couple years back, I thought about building a new one. So that’s what I decided to do. I ordered from PML phenolic tubes, 1/8” thick Aurora fins, couplers, and a nosecone. I decided not to order the Aurora tailcone for this build of the Ladyrobin.
 

n3tjm

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First step in building is fiberglassing the tubes. It took half an hour to glass each tube, and I wrapped them with cellophane, and put them in my hot car. And they were fully cured in two hours. The next day I sanded the excess epoxy off the tubes and cleared the slots.
 

n3tjm

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Actual construction started with the motor mount. There are three centering rings in the design of the Ladyrobin. The Aft Centering ring holds two blind nuts allowing motors to be anchored with dual boats. The ring above the fins is a standard centering ring, nothing fancy about it. The Fwd Centering Ring holds the eyebolt for the recovery system to be anchored to, and is sized to fit inside the tube coupler.
First batch of epoxy was used to attach the middle centering ring to the motor tube, and to set the blind nuts and eye bolt on the other centering rings.
 

n3tjm

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Then the motor mount is cemented into the short slotted body tube. At first only the center centering ring is epoxied into place. So to make sure the motor tube is centered, the aft ring and fins are dry fitted.
 

n3tjm

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Before the Fwd centering ring is attached, the motor tube has to be trimmed to its final length. The tube coupler and Fwd CR is dry fitted to mark the tube to be cut, then it was time to get out the razor saw. Then the tube coupler is epoxied into place, followed by the fwd centering ring.


 

n3tjm

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The fins are then glued in place. Once the epoxy is cured, internal and external fillets are applied. The fincan is finished when the Aft Centering Ring is epoxied in place.



 

n3tjm

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I wanted to make the electronics bay with material I had on hand, so minus the tube coupler I ordered, everything else is from parts I already have, or salvaged from the Megablast. First up, making the “stiffy tube” that goes inside the tube coupler. The tube provides the block for the bulkheads to rest against, and adds significant strength to the tube coupler. I did not have an extra LOC Stiffy Tube in stock, but I did have two LOC 4” tube couplers. So I decided to make my own. The LOC couplers are the same length as the PML coupler, so I made each LOC coupler ½” shorter. Then I removed material from the length of each loc coupler so they can fit inside the pml coupler. Once that was done, I epoxied both LOC tubes inside the pml tube.


 
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