Minimum Diameter - K2045

[HaackIt]

Haven't had time to keep up any sort of a build log - maybe I'll get to posting soon, but I thought you guys might like this:

Stats:
5lb fully loaded
106G max acceleration
17G max deceleration

Top speed / Burnout: Mach 1.88 @ 384 ft AGL
Coasted to 13,048 ft AGL

Finished:


On the pad:


Sorry for the bad video - I was a bit preoccupied to focus on recording.
[video=youtube;0kqEIX0QdG8]https://www.youtube.com/watch?v=0kqEIX0QdG8&t=32s[/video]

Still hoping to get some drone footage plus some video from the 360 degree cameras sitting right next to the pad as well as on the flight line.

If anyone has any more pictures/videos of my launch at October Skies, please let me know!

 

[JimJarvis50]

Haven't had time to keep up any sort of a build log - maybe I'll get to posting soon, but I thought you guys might like this:

Stats:
5lb fully loaded
106G max acceleration
17G max deceleration

Top speed / Burnout: Mach 1.88 @ 384 ft AGL
Coasted to 13,048 ft AGL

Nice flight! I have a small 3" rocket that I fly on the K2045. It'll do around 9K, but it does it very quickly, and people seem to enjoy it. What I find interesting about my flights, and yours would be even better, is how low the rocket is when it passes Mach 1.

Jim

 

[HaackIt]

What I find interesting about my flights, and yours would be even better, is how low the rocket is when it passes Mach 1.

According to the Raven's accelerometer, it looks like I hit 1125 fps @ ~201ft AGL (0.38 seconds into the flight)

Baro was only reading 69ft at that point, but it's going to lag for a bit.

 

[HaackIt]

I tracked down some photos of the fin can:

Didn't get any pictures of the fins closely after they were cut out, but I did run a test cut in aluminum and I think they look pretty cool.

These are pretty much the space cowboy fins - most of the time cutting them was spent building jigs to hold everything.


Alignment jigs cut and fins initially attached - fins are black G10:


Fillets Poured:


Carbon Fiber tip to tip - vacuum bagged:


1 of 3 done:

 

[SpaceManMat]

Very nice. Daimond foiled fins always does it for me.

Tell me how do you do the second side of the fins? Do you simply leave enough support material on the edges until you've shaped both sides?

 

[BDB]

I agree. The fins look great. Can you tell us a little more about how you beveled them into a diamond shape?

 

[Lowpuller]

Why do you vacuum bag? Smoother surface? How do you get the bag off?

 

[BDB]

Why do you vacuum bag? Smoother surface? How do you get the bag off?

I haven't bagged a layup yet, but I plan to do it in the near future. The compression applied by the vacuum squeezes out excess epoxy, making the layup strong but light. There is a layer of teflon peel ply between the layup and the vacuum bag which makes for a smooth surface and prevents the bag from bonding to the fins.

 

[HaackIt]

The compression applied by the vacuum squeezes out excess epoxy, making the layup strong but light. There is a layer of teflon peel ply between the layup and the vacuum bag which makes for a smooth surface and prevents the bag from bonding to the fins.

^ Exactly - I just wish I sprang for carbon fiber fins / body tube instead of fiberglass. My goal was Mach 2 and I came in a bit too heavy.

Tell me how do you do the second side of the fins? Do you simply leave enough support material on the edges until you've shaped both sides?

I couldn't really leave much material on the edge. The thinnest point on these fins is 0.007" thick. I cut jigs to use on each side. They use locator pins to align the jigs to the table and the material to the jig. One the second side I have the negative of the first side cut out... Then used spray adhesive to hold things in place.

Here's the plate I use to hold the material for the second side:

 

[NateLowrie]

Really like the jigs. What CNC are you using? Looks like it might be a Joe's but I am not sure.

Regarding the shape of the fin; Why is the tip cord a slight V instead of flat? Just looks?

 

[HaackIt]

Really like the jigs. What CNC are you using? Looks like it might be a Joe's but I am not sure.

Regarding the shape of the fin; Why is the tip cord a slight V instead of flat? Just looks?

Joes 4x4 Hybrid (R&P). I've had it for 5-6 years now and it still works great!

I didn't design them - they are the Space Cowboy fin design. You can buy them from Chris as well - I just liked the challenge of cutting them myself.
https://www.ape-rc.com/#!/Double-Ta...4mm-Space-Cowboy/p/47861385/category=11909535

Chris has more history on them - we just talked about them at October Skies.

 

[ChrisAttebery]

The shape came from the original Space Cowboy kit. It's the shape you get when you take the two sets of Dark Star fins and remove the gap between them. You can thank Crazy Jim for that.

 

[NateLowrie]

Joes 4x4 Hybrid (R&P). I've had it for 5-6 years now and it still works great!

I didn't design them - they are the Space Cowboy fin design. You can buy them from Chris as well - I just liked the challenge of cutting them myself.
https://www.ape-rc.com/#!/Double-Ta...4mm-Space-Cowboy/p/47861385/category=11909535

Chris has more history on them - we just talked about them at October Skies.

Good stuff. Looking forward to the rest of the build.

Regarding the vacuum bagging, what's your process and how do you manage the edge of the carbon fiber? Do you do it like an unbagged tip to tip and leave some overhand to be trimmed when the epoxy is in the leather stage?

 

[watermelonman]

Little sucker moved fast -

 

[HaackIt]

Little sucker moved fast

That is an awesome shot - thanks! I PM'd you - if you have a larger photo, I'd love to see it.

 

[HaackIt]

Regarding the vacuum bagging, what's your process and how do you manage the edge of the carbon fiber? Do you do it like an unbagged tip to tip and leave some overhand to be trimmed when the epoxy is in the leather stage?

Yes, basically - I allowed the CF to run past the edge, then trimmed it.. Sometimes I caught it before it was completely cured... sometimes I didn't (and paid for it).

 

[HaackIt]

More build photos!

It was somewhat of a tight squeeze to fit 2 Ravens and a BeeLine GPS into the coupler tube I used for my nosecone shoulder. The only thing in the nose cone was the antenna.

 

[mlrtime99]

Any other disassembled pictures? I'm curious about your recovery arrangement if the only thing in the nosecone was the antenna.

 

[HaackIt]

Any other disassembled pictures? I'm curious about your recovery arrangement if the only thing in the nosecone was the antenna.

You can see in the second picture posted above the electronics.... there's another Raven/Battery on the other side. All of the electronics are on that sled which fits in a very long shoulder for the nose cone (replaced shoulder supplied with a length of coupler tube). The antenna (yellow) sticks out into the nose cone to within an inch of the tip.

 

[blackjack2564]

The shape came from the original Space Cowboy kit. It's the shape you get when you take the two sets of Dark Star fins and remove the gap between them. You can thank Crazy Jim for that.

Actually the other way around......DarkStar fins came from the SpaceCowboy fin....just split the fin in middle, to make 2.....LOL

Real nice clone you have there, you did a great job building/flying it. Now go stick a big 6xl grain in there & let it rip...ya know that's what it really wants to do!!

 

[ChrisAttebery]

Ok, I got it backwards. Story of my life. LOL!

L640 FTW!

 

[HaackIt]

Now go stick a big 6xl grain in there & let it rip...ya know that's what it really wants to do!!

That's the plan... of course I can't do that and stay under our waiver in central California (and finding a CTI 6xl motor is proving difficult).