David - 3" Flying Case to 60,000 ft

[diyaerospace]

A project that a friend and I are working on.
Taking inspiration from Bare Minimum, FROG, and other high performance builds.

Specs:
Design apogee > 45,000
Peak velocity of around mach 3.6
Experimental M class motor
3" subminimum diameter

Fincan:
3/16 carbon plate
Bent steel LE protection
Es6209 fillets
Sleeve or roll wrapped tube


Nosecone:
Hand laid with 8-9 fiberglass sleeves to match casing wall thickness
Aluminum tip


Electronics:
Nosecone AV bay
Blue Raven
Easymini
Featherweight Tracker
RDF Beacon
Lyra(A custom developed flight computer for datalogging and backup telemetry)


Recovery:
Redundant vinyl tube charges
Drogue at apogee.


Tower:
Send Cut Send 1/8in aluminum rings or hand cut 3/4in plywood
1010 rails for adjustable spars as well as the primary rails
Adjustable from 29mm to 98mm

Test Flights:
Two EX L1000 clones flying to 25k and 30k respectively to test fincan construction techniques and recovery configurations.

 

[diyaerospace]

Now into some of the details...

Won't go into the motor design much, but it's a custom aluminum casing and prop load that's slightly longer than the 6gxl casing from CTI.

There isn't much special about the nosecone/AV bay. It interfaces with the forward retaining ring (not shown) of the motor.

The fincan is where we're most undecided on, specifically manufacturing the fins themselves. At the minimum we'll bevel a hexagonal airfoil into them (RAS sims are currently set with 1" LE/TE length and a radius of 1/16"). However, there is a drag benefit to using something like a biconvex airfoil. We'll make some fin prototypes soon to test the manufacturability of different airfoils and fit with the steel endcaps on the LE.

We're also undecided on exactly what carbon plate to use. High temp Dragonplate is the obvious solution that would very likely survive the flight. However, it's really expensive and we'd prefer to explore some other options before going down this route.
Also worth mentioning that a printed aluminum fincan isn't off the table. I've successfully used them before with the only real downside being that their cost gets exponentially more expensive as the diameter increases. The total cost is still comparable with a Dragonplate fincan though.

The last major component is a machined tailcone that also acts as a expansion cone for the nozzle.

Needless to say, the current design is pretty performant and we'll likely cut back on some of the optimizations in the future.

Thanks,
Walter

 

[FredA]

Interesting project.
Target is 45k or 60k?
Where would you have a fincan printed if you went that route? Who have you used?

 

[diyaerospace]

Interesting project.
Target is 45k or 60k?
Where would you have a fincan printed if you went that route? Who have you used?

Target is >45,000 feet, but 60k looks possible.

Craftcloud. I got a 54mm fincan printed there for $120 including shipping. A 3" fincan is about $300.

 

[bad_idea]

Target is >45,000 feet, but 60k looks possible.

Craftcloud. I got a 54mm fincan printed there for $120 including shipping. A 3" fincan is about $300.

$300 seems very reasonable compared to the overall cost of your project.

 

[diyaerospace]

$300 seems very reasonable compared to the overall cost of your project.

The BOM of this vehicle is pretty low as of now (<$600). But that will increase as we continue to flush out the fincan design. A printed aluminum fincan increases the total cost significantly but it may end up being the cheapest and most effective option we have.

 

[James Keller]

Can you go into any more detail on how you made the tailcone(Major/Minor Diameter, what its made of, and how it relates to the nozzle)? Dig the project best of luck!

 

[diyaerospace]

Can you go into any more detail on how you made the tailcone(Major/Minor Diameter, what its made of, and how it relates to the nozzle)? Dig the project best of luck!

The tail cone machining will either be outsourced to JLCPCB or done in-house. It's just aluminum.

Major/Minor diameter was determined by playing with RASaero to find what dimensions give the most performance.

 

[MClark]

Bent steel LE protection

Where are you planning on launching?
Steel is a no go for a Tripoli launch.

 

[diyaerospace]

Where are you planning on launching?
Steel is a no go for a Tripoli launch.

Friends of Amateur Rocketry.

 

[diyaerospace]

Thought i'd give you guys an update on one of the "test rockets" flying next weekend.

It's a 54mm submin flying on a experimental slower clone of the L1000...
Goals are to test the recovery configuration and fincan construction techniques.

Sim:


Nosecone:

Hand laid with 5 "light" sleeves from Soller composites. The fit between the coupler and nosecone required some sanding to fit together nicely.

Next I cast a epoxy tip onto the nosecone. I embedded a 1/4-20" threaded rod into the tip for the nosecone AV bay.

3d printed mold with some super lube as mold release. The epoxy used here is just JB weld high strength.


Very happy with how this nosecone turned out, now onto the AV bay!


AV bay:


I flew this exact AV bay on my 38mm submin, hence why it's so packed. Figured i'd reuse it here.

Easymini
Featherweight GPS tracker
Custom FC for datalogging + telemetry
RDF beacon

Fincan:
Still a WIP, but the plan is some shitty 3/16 amazon carbon plate cut and beveled by hand. Fillets are with proline on a hand laid tube.
My first attempt at laying up the fincan tube got stuck on the mandrel (54mm fiberglass casing offcut).

Think I may have broken the condom (mold release) during the layup.
Just laid up a second attempt.



Some other random details.
Proline + Q cells as LE protection for the fins.
Vinyl tube charges
Either a 9" main at apogee or just some nomex as recovery.
3d printed tailcone with some proline as heat protection.

Pretty excited for this flight!

Thanks,
Walter

 

[diyaerospace]

Clarification on the original post. I'm working with @polariss on this project.

 

[LogicPenguins]

Best of luck! Awesome project.

 

[diyaerospace]

Here's another progress update on one of the test rockets.


My second attempt at demanding a tube for the fincan didn't work, it moved about an inch before getting stuck. This is when I switched to just glueing the fins to the EMK.

The fins themselves were cut by hand with a hacksaw and beveled with sandpaper. It was a very painstaking process lol.
The first thing I did was pot the nozzle of the EMK into the casing and tack the fins on.



The jigs I used were laser cut from acrylic and sized for a fincan OD, since I switched to a casebonded design I had to shim them with a lot of tape.

Nevertheless, the alignment was pretty perfect with almost no cant.

Then I moved onto fillets. I used a 0.75" radius and proline 4500 epoxy.

Pretty happy with how these turned out!

The last thing I experimented with was using proline + Q cell filler to make a ablative layer that I added to the LE of the fins and tailcone. I used way too much filler here so some sanding is required.



I painted the nosecone in proline epoxy before sanding it down to try to improve the surface finish.

Pic after sanding.

It was around this time that I finished assembling the EMK and potted the coupler in place.



Recovery setup is just some shockcord and nomex as mentioned before.

Another important development is that i've switched the motor to use some slower white grains from rcs because the prop that was cast for this motor didn't fully cure. This drops the altitude to 25k and max speed to mach 2.3.



Here's the finished rocket:



I'm very pleased with how this build has turned out, hopefully the launch is just as pretty.
I'm going to arrive at FAR tomorrow night and launch Saturday morning.

Thanks,
Walter

 

[diyaerospace]

Picture from Julian Rice

 

[diyaerospace]

Alright, here's the flight report.

It launched around 12 pm on Saturday. The flight was pretty textbook.
Successful boost to 22,000 ft.
Successful deployment and tracking.

We drove about 3 miles on the FAR road and walked the last mile. The Featherweight tracker led us right to it.

We found the rocket with a broken fin, which was expected given the recovery system was just a small sheet of nomex. All the expensive/reusable stuff is fine.


You can see a lot of aeroheating on the tailcone which is cool.

When we walked up to it


The only scary thing about this flight was that the backup charge failed to fire. The ematch went but didn't light the bp.


Very happy with how this flight turned out. The 3" main project is now scheduled for April 6th at FAR.

Attached are all the pictures and launch video. Thanks @tsbooska for helping me integrate.

 

[rfjustin]

Alright, here's the flight report.

It launched around 12 pm on Saturday. The flight was pretty textbook.
Successful boost to 22,000 ft.
Successful deployment and tracking.

We drove about 3 miles on the FAR road and walked the last mile. The Featherweight tracker led us right to it.

We found the rocket with a broken fin, which was expected given the recovery system was just a small sheet of nomex. All the expensive/reusable stuff is fine.

View attachment 635920
You can see a lot of aeroheating on the tailcone which is cool.

When we walked up to it
View attachment 635921

The only scary thing about this flight was that the backup charge failed to fire. The ematch went but didn't light the bp.
View attachment 635923

Very happy with how this flight turned out. The 3" main project is now scheduled for April 6th at FAR.

Attached are all the pictures and launch video. Thanks @tsbooska for helping me integrate.

I may have missed the mark, what are these holes for in the cone? Arming?

 

[diyaerospace]

I may have missed the mark, what are these holes for in the cone? Arming?
View attachment 636017

Yep, arming.

I painted the nosecone in proline which made it a lot more difficult to judge where to drill them, hence the shitty workmanship.

 

[rfjustin]

Yep, arming.

I painted the nosecone in proline which made it a lot more difficult to judge where to drill them, hence the shitty workmanship.

So what, she worked! "Successful boost to 22,000 ft... Successful deployment and tracking..." You showed up, you flew it, it didn't shred, it deployed, and was recovered, that's a win baby!

Cheers!

 

[Hobie1dog]

 

[vulpesjr]

We found the rocket with a broken fin, which was expected given the recovery system was just a small sheet of nomex. All the expensive/reusable stuff is fine.

View attachment 635920

Hard to tell from this photo, but did the fillet epoxy itself fail in shear? Or are there sections that debonded from the case/fin?

 

[diyaerospace]

Hard to tell from this photo, but did the fillet epoxy itself fail in shear? Or are there sections that debonded from the case/fin?

The fillet itself failed in shear.

 

[cwbullet]

I love it. Did it shear a fin?

 

[diyaerospace]

I love it. Did it shear a fin?

Thanks,
It did shear a fin

 

[vulpesjr]

Did the 54mm submin have proline fillets? And the 3" rocket is going to have hand-laid carbon plates with dp420 fillets, right? What's the fillet radius going to be on the 3" rocket fins?

 

[diyaerospace]

Did the 54mm submin have proline fillets? And the 3" rocket is going to have hand-laid carbon plates with dp420 fillets, right? What's the fillet radius going to be on the 3" rocket fins?

Yeah the 54 submin had proline fillets. The 3" is EP420NS fillets on hand laid plate, haven't decided on a radius yet.

 

[diyaerospace]

Here's an update on the 3" rocket.

Sims:
Running sims on a more sane motor configuration. Altitudes are around 50k.



Fincan:
Committing to a 4x roll wrapped CF tube, with 14-ply 3K plain weave plate, all made from scratch by @tsbooska Fillets are gonna be EP420NS from infinitybond, with proline LE protection.
Goal is a cheap carbon fin can that's built like a tank.

Tube layup has already been completed.






Seam will go adjacent to a fin and get covered by the fillet.



Nosecone:
Laid this up with the same techniques as the last one.

3d printed mold with two condoms as mold release.

Regular size condoms just barely fit over a 3" submin nosecone.


Laid up with 9 soller "light" 3" sleeves to match the casing wall thickness. Hung under tension to get good consolidation of the sleeves.

About 7 hours later, I hacksawed the ends off and knocked the mold out.


9 sleeves is defiantly overkill from a strength perspective. The wall thickness is just silly at the tip.


The 2.6" straight section feels like not enough coupling area, but it shoullllldd be fine?

Pretty happy with how this nosecone turned out. Going to apply a proline coat and sand it smooth to improve the surface finish.

Avionics:
Finished cadding the AV bay.


Featherweight GPS tracker, custom flight computer (Lyra), and either 2x Easyminis for deployment or one Easymini and one Blue Raven.
Got some tiny screw switches from @Maxwelljets on there and 400 mah lipos to power everything.

Printed.


Started mounting stuff to it, still a long ways to go though.


Fits nicely into the nosecone.


In other news, the motor casing stock arrived. It's pretty big lol


Still tentatively hoping for a launch on april 6 depending on machining times.

Thanks,
Walter

 

[vulpesjr]

Looking good! That av bay is clever, I like it

 

[diyaerospace]

I've been really busy the last week prepping, but here's what happened.
The rocket launched on April 6 and achieved an altitude of 41,800 feet agl and mach 3. The rocket landed nominally under drogue and has yet to be recovered.

I'll go over progress on each part of the build one by one.

Fincan:
Custom plate was made with 17 plies of carbon fiber, a wet layup and a vacuum bag.




Fins were cut out with a pneumatic rotary tool and a 3" diamond tile saw


Bevels were done on a belt sander.


Tacking was done with laser cut jigs and some 3d printed alignment pieces.


Fillets and LE protection was done with EP420.


And here's the finished product on its way to FAR!


All credit for the fincan should go to @tsbooska who made it. Thank you so much, it totally survived the flight.

 

[diyaerospace]

Nosecone

I painted the nosecone with a second coat of proline 4500 epoxy and sanded it flat. I'm pretty happy with the surface finish I got.


The nosecone tip was machined by @Brainstormz123



Recovery:

I used 2,000 lb kevlar from amazon on this. In hindsight I would have gotten better kevlar because this stuff packs like **** and is a pain to work with.
Anyway, 5 breakloops with 3-5 wraps of tape on each.


I used coupling nuts with holes drilled through them as mounting points for the shockcord. I was careful to secure the kevlar in place to prevent the sharp steel edge from cutting through it.


Deployment was done with a single easymini with 1.5 and 3g main and backup charges.

The actual chute was a last minute addition on friday night. It was a reefed 18" from Topflight. In hindsight I wouldn't have reefed the lines as it wasn't able to provide enough drag to keep the vehicle in a flat spin on descent.

Electronics:
Not much new to say about the AV bay. It worked great, got the chutes out, had good tracking and tlm, and hopefully has some data on motor performance.