Cormoran II

Hi everyone,

After designing and building Comoran I, I decided to move on and create version 2.0. I wanted a few things for this build:

• Needs a payload area
• Fins must be strongly attached to the frame (I had a problem with this on my previous build)
• Compatible with 24mm motors, both 70mm and 95mm long.
• Easy to assemble and replace parts.
• Improved motor mount with a hook instead of friction mounting.

I started with a rough mock-up in OpenRocket, then I modelled everything in Fusion360.






The rocket is 610mm tall, uses 34mm BT and 3 fins (34mm height). I will be posting the OpenRocket files in the Plans section soon!

Now to the build:

I decided to use a cardboard tube for the airframe as 3D printing it was really time consuming on my previous build and not as light as I would like. The rest of the parts are 3D printed.



The blue parts are printed using PETG, which should withstand the temperatures much better. For the black ones, I used standard PLA. The fins are printed as one with the bottom of the airframe, this makes a stronger structure than my previous one, although it may not be enough in case of a rough landing.


That's all I have for this weekend, in the following days I will assemble the motor mount, adjust the size of the body tube and finishing the electronics package.

Thanks a lot.
~Nacho.

Looks great!

With Your slight forward sweep of fin rear edges, and if your motor sticks out a bit, I think your fins will survive landings well,

BABAR said:

Looks great!

With Your slight forward sweep of fin rear edges, and if your motor sticks out a bit, I think your fins will survive landings well,

Click to expand...

Thank you! The motor hook will stick out a bit for sure, maybe that will help

Update time!

I did cut the body tube down to final length, I also made the holes to screw it to the bottom section, in the pictures below I show a trick I used to perfectly drill holes in a circular pattern. I also soldered my "fly computer", I got a few Arduino compatible PCBs, however, the Nano won't fit across so I have some pins just hanging in one side...

I also glued the motor case to the main body coupler.

Pictures:











Next steps, I want to add some strength to the top and bottom of the frame, I will be adding a thin layer of glue probably. Before putting together the base and the motor mount, I want to do a fit test with a motor (should arrive by the end of the week). I need to print a few more things, namely, something to close the payload area, motor retainer and a launch tube.

Regarding the electronics, I need to write the code that will track the max altitude of the rocket.

Thats it for now!
Thanks!
~Nacho.

Maiden flight happened this weekend, really nice, almost perfectly vertical! The chute deployed as planned. However, the rocket landed on a tree . Today I tried to recover unsuccessfully. Sadly, I'm not sure if I will recover it.

In any case here a picture of the launch:



Sorry for the low quality picture, I need to invest in some better recording equipment hehe.

I'm a bit disappointed with this bittersweet ending for this model. However, I think I will rebuild it as it did fly quite nice!

Thanks a lot.
~Nacho.

Nacho said:

Maiden flight happened this weekend, really nice, almost perfectly vertical! The chute deployed as planned. However, the rocket landed on a tree . Today I tried to recover unsuccessfully. Sadly, I'm not sure if I will recover it

Click to expand...

ARGH, yeah, trees are the worst. It looks good, though, I think worth a re-build!

Congrats on a completed project, although the rocket loss bites. Did you have electronics on board? The rest of the stuff seems readily easily replaced.

HereS to Cormoran III!

mbeels said:

ARGH, yeah, trees are the worst. It looks good, though, I think worth a re-build!

Click to expand...

Yeah! And if there is just 1 tree in 10miles around, you have a 99.9999% chance of hitting it haha.

BABAR said:

Congrats on a completed project, although the rocket loss bites. Did you have electronics on board? The rest of the stuff seems readily easily replaced.

HereS to Cormoran III!

Click to expand...

Thanks, it was carrying a dummy payload so no electronics .


I think I will give this another try: rescue 2.0! I'm going to use a long rope with a rock attached at the end. I just can't leave a soldier hanging there!!!

I will keep you updated on the status of the mission.

~Nacho

Nacho said:

The blue parts are printed using PETG, which should withstand the temperatures much better. For the black ones, I used standard PLA. The fins are printed as one with the bottom of the airframe, this makes a stronger structure than my previous one, although it may not be enough in case of a rough landing.

Click to expand...

ABS can take a bit higher temps than PETG in use as seen on parts new 3d printer hot ends that get soft while
ABS parts don't. I print a lot of stuff in ABS in part due to the heat here in the Southeastern US which melts me
and surely will soften PLA a lot.
Now if you really want high temp parts print them in nylon but nylon takes some work to print well....

Hi there!
After a break from rocketry, this last week I decided to build a new Cormoran II. Today I woke up and it was quite sunny... so you all know what it means!



The flight was quite good overall. I noticed that during the first instants of the flight, the rocket made quite a hard left turn. I think the problem is that the launch rod I'm using is not long enough. In openrockeck I have a rod length of 1000mm and that should allow the rocket to reach 15m/s (50ft/s) but the real one is more like 7000mm and I'm not even using the full size of that. Apart from that, this is the first time I have a look at the rocket after flying and there are a few things I will consider for next builds. Using 3d printed parts near the motor is a bad idea if you want to reuse them , also the shock cord I'm using doesn't like heat either.

Anyways, this was a great experience, now I want more!
See you all.
Nacho.

Very nice! Glad you gave it another go. I'm sure the next one will be even better.

Congrats! I liked the victory salute with the rocket at the end of the recovery walk!

BABAR said:

Congrats! I liked the victory salute with the rocket at the end of the recovery walk!

Click to expand...

Thanks! I think I'm more happy about recovering it succesfully than anything else!

I have been working on a new revision of Cormorán II, this is a bit bigger overall (650mm long, 42mm diameter). I changed the nose cone, for a lv-haack one, and more importantly, a bigger payload area with space for a flight computer and a camera!



I need to finish a few things, but hopefully, I will be flying soon!

That is it for now.

Nacho said:

Thanks! I think I'm more happy about recovering it succesfully than anything else!

Click to expand...

Having an intact rocket safely in your hands after recovery is like the best feeling in all of rocketry.