54mm flying case testbed

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Great flight. Hopefully I don't get too annoying asking folks this question here, but what was your max fin thickness? And more evidence that tip to tip is not a requirement for truly aggressive flights!
 
robopup said:
Great flight. Hopefully I don't get too annoying asking folks this question here, but what was your max fin thickness? And more evidence that tip to tip is not a requirement for truly aggressive flights!
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The fins were cut from a piece ot 1/8" T1100 plate from Rock West Composites that I had left over from a different project.

I'm in full agreement with you about tip to tip. Someone else at BALLS this year had a 98mm rocket go sideways at Mach 3, possibly due to the nosecone or upper airframe failing. The fins were carbon plate and were held on with good structural epoxy, and they were all still attached.

That said, I am still tempted to build a fincan like the M3R rocket that @bandman444 built a while back, and that used a significant amount of prepreg tip to tip to form the bulk of the fin can tube.
 
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I know this gets away from the flying case intent but have you sim'd what a flight would look like if you fully enclosed the motor in a BT? A small weight penalty to avoid the leading edge damage to the fin can. I suspect you have another solution to the leading edge damage on the fin can but figured I'd ask the obvious.
 
wsume99 said:
I know this gets away from the flying case intent but have you sim'd what a flight would look like if you fully enclosed the motor in a BT? A small weight penalty to avoid the leading edge damage to the fin can. I suspect you have another solution to the leading edge damage on the fin can but figured I'd ask the obvioussleevehaven't actually simmed a regular minimum diameter version of this design. My main goal with this rocket was never outright altitude performance, but to try out my ideas on a relatively small scale before attempting some higher performance records.
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For the fin can leading edge, I'm tempted to just cut off the top half inch and call it good. The only area that failed was where it was only one layer of sleeve thick. For future builds, I'll probably have an Aluminum leading edge made.

It's my opinion that a leading edge with a shallow enough taper will mitigate the drag penalty of the step enough for submin to be at least on par with a traditional min diameter rocket.

My long term goal with extreme performance rockets is to switch to using composite motor cases, which would allow me to bond the fins directly to the motor, and eliminate the fin can altogether. That's a long way off, and I'd like to get good at submin rockets before that.
 
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I'm getting Pathfinder ready to fly again this Saturday at FAR.

The fin can needed a bit of work. The leading edge damage was easy to fix with a hacksaw and a bit of sandpaper. I have ideas about getting a metal leading edge made, but I don't have the time or money to get it ready by Saturday. I think that it was mostly a structural issue, and that leaving it at two layers thick with a relatively blunt bevel on the top should be sufficient. The other thing that needed doing was sanding it to fit the motor case. Apparently the motor case that I used as a mandrel was a bit smaller in diameter than the motor case I used to fly at BALLS, and the one I have for this flight is even larger still. I spent a lot of time and effort sanding it to fit on the Playa, so I got a cylinder hone from Harbor Freight to speed up the work. It's not quite as loose of a fit as I'd like, but it fits much better now.

Pathfinder fin can.jpg
(please pay no attention to the bit of glue on the fin that I still haven't properly cleaned up....)

The big problem I faced at BALLS was recovery volume. I needed all of my weight to get the nosecone on, and didn't have space for a cable cutter. I've learned my lesson about being optimistic on recovery volume for future projects, but that doesn't really help me now. Ultimately I realized that what I thought was a 24" parachute was actually a 30" parachute, and I don't actually have a 24" thin mill parachute. So now I need to find or make a parachute in time for Saturday...
 
Neutronium95 said:
I'm getting Pathfinder ready to fly again this Saturday at FAR.

The fin can needed a bit of work. The leading edge damage was easy to fix with a hacksaw and a bit of sandpaper. I have ideas about getting a metal leading edge made, but I don't have the time or money to get it ready by Saturday. I think that it was mostly a structural issue, and that leaving it at two layers thick with a relatively blunt bevel on the top should be sufficient. The other thing that needed doing was sanding it to fit the motor case. Apparently the motor case that I used as a mandrel was a bit smaller in diameter than the motor case I used to fly at BALLS, and the one I have for this flight is even larger still. I spent a lot of time and effort sanding it to fit on the Playa, so I got a cylinder hone from Harbor Freight to speed up the work. It's not quite as loose of a fit as I'd like, but it fits much better now.

View attachment 615524
(please pay no attention to the bit of glue on the fin that I still haven't properly cleaned up....)

The big problem I faced at BALLS was recovery volume. I needed all of my weight to get the nosecone on, and didn't have space for a cable cutter. I've learned my lesson about being optimistic on recovery volume for future projects, but that doesn't really help me now. Ultimately I realized that what I thought was a 24" parachute was actually a 30" parachute, and I don't actually have a 24" thin mill parachute. So now I need to find or make a parachute in time for Saturday...
Click to expand...

You should get aluminum duct tape and one layer from the motor over the front edge of the fin can .
 
3stoogesrocketry said:
You should get aluminum duct tape and one layer from the motor over the front edge of the fin can .
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If there was a way to get aluminum tape to shear cleanly off I'd say go for it. But since aluminum tape isn't THAT sticky, and it's bonded directly to the motor case (which may or may not get a little bit hot) it would end up causing drag before it was useful. If it would fit, you'd wanna wrap the aluminum tape around the leading edge of the can, although that would make the step up from the case to the can alot more prominent and likely cause some parasitic Shockwaves to form along the leading edge (which is worse). I love aluminum tape so much, I just don't think you can yeet it to above mach 2 bonded directly to a motor and it still stick without mushrooming like the kevlar.
 
Seatechnerd83 said:
If there was a way to get aluminum tape to shear cleanly off I'd say go for it. But since aluminum tape isn't THAT sticky, and it's bonded directly to the motor case (which may or may not get a little bit hot) it would end up causing drag before it was useful. If it would fit, you'd wanna wrap the aluminum tape around the leading edge of the can, although that would make the step up from the case to the can alot more prominent and likely cause some parasitic Shockwaves to form along the leading edge (which is worse). I love aluminum tape so much, I just don't think you can yeet it to above mach 2 bonded directly to a motor and it still stick without mushrooming like the kevlar.
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Although, when I'm able to get L2 this is why I'd love to be able to make a high Mach 2 test rocket to be able to test stuff out like this.
 
Recovery was less than ideal. It looks like the cable cutter worked, but the main didn't open. Fortunately it looks like all of the electronics survived. Just need to make a new nosecone.
1000010813-jpg.625167
 

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You are incorrect about aluminum tape though. I have used it for 25 years on rc planes and jets. The backing is so sticky that if I made a mistake and needed to remove a piece, it usually took the layer of fiberglass off with it:(
 
Great photo btw!

Interested in altitude reported on the K2050.
Closest comparison I have went 5400ft on a 4” fiberglass rocket a few months ago, same motor.
 
What a beautiful liftoff photo, @Neutronium95 !

I can't tell for sure from the recovery photo but it looks like maybe the leading edge of the fin can fared better this time ?

Did you get any data from the electronics ?

Thanks for the report !

-- kjh
 
kjhambrick said:
What a beautiful liftoff photo, @Neutronium95 !

I can't tell for sure from the recovery photo but it looks like maybe the leading edge of the fin can fared better this time ?

Did you get any data from the electronics ?

Thanks for the report !

-- kjh
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The fin can is in almost perfect condition.

It looks like one chip got knocked loose on the Blue Raven, but it was working fine when I found it and all of the data downloaded fine. I'm going to contact Adrian to see if it's repairable.
 

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