fyrfytr310's Level 3 - Polecat 10" Nike Smoke

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Finally lost my patience trying to scrap the excess foam off the nose bulk plate. It is what it is.

I've put a fillet between the plate and the shoulder and that should complete the cone structurally.

ImageUploadedByRocketry Forum1476451585.903188.jpg

The last of the fin fillets are curing as we speak and I should be back to glassing this evening.

Question for the tip to tip pros. Do you prefer to cut to shape first or do you use a larger sheet and cut once saturated and in place?
 
fyrfytr310 said:
Finally lost my patience trying to scrap the excess foam off the nose bulk plate. It is what it is.

I've put a fillet between the plate and the shoulder and that should complete the cone structurally.

View attachment 303307

The last of the fin fillets are curing as we speak and I should be back to glassing this evening.

Question for the tip to tip pros. Do you prefer to cut to shape first or do you use a larger sheet and cut once saturated and in place?
Click to expand...

Here's my procedure:
  1. trace the areas needed onto paper.
  2. Enlarge area 1/2' on each side.
  3. Cut out paper to use as template.
  4. Use the tamplate to trace a light line on the fiberglass.
  5. Put masking tape over the lines. This keeps the ends of the fiberglass from fraying when cut. half the tape should be on each side of the line.
  6. Cut out pieces cutting in the appoximate middle of the tape.
  7. Do your tip to tip and saturate in place. Leave the excess on until the leathery stage. For West Systems it's roughly an hour after pot life. That's an ideal time to trim it.
  8. After trimming, I thinly recoat the leading and trailing edges with an epoxy brush.
 
NateLowrie said:
Here's my procedure:
  1. trace the areas needed onto paper.
  2. Enlarge area 1/2' on each side.
  3. Cut out paper to use as template.
  4. Use the tamplate to trace a light line on the fiberglass.
  5. Put masking tape over the lines. This keeps the ends of the fiberglass from fraying when cut. half the tape should be on each side of the line.
  6. Cut out pieces cutting in the appoximate middle of the tape.
  7. Do your tip to tip and saturate in place. Leave the excess on until the leathery stage. For West Systems it's roughly an hour after pot life. That's an ideal time to trim it.
  8. After trimming, I thinly recoat the leading and trailing edges with an epoxy brush.
Click to expand...

One thing nobody seems to point out in using the taped edge to cut is WHEN to remove the tape? During leather stage or post cure?
 
rharshberger said:
One thing nobody seems to point out in using the taped edge to cut is WHEN to remove the tape? During leather stage or post cure?
Click to expand...

I don't remove the tape. The tape is on the overhang of the piece. It gets removed when I trim the fiberglass overhang. Post cure trimming is a PITA on tip to tip. You need to trim the overhang on the airframe by the leather stage at the latest. If you let it cure you're sanding it off.
 
Just wanted to stop in to say I'm almost done with the tip to tip. And I suck at glassing. Jeez. If I am successful with this cert, I think I am done with glassed cardboard. No. if this fails, I'm still done with glassed cardboard. My patience is not where it needs to be for this kind of work and I'm too wasteful lol.



ImageUploadedByRocketry Forum1476567043.166153.jpg
 
You're right about that Mike. If you have no plans of going stupid high or stupid fast think of it as adding resilience to the rocket so a structural hit on landing doesn't disqualify the attempt.

BTW, from 10 feet out, no one is going to notice the finish on the rocket anyways. Make it so it can withstand the rigors of your planned flight and call it good. Kurt
 
Good hit on the electronics sled this evening.

ImageUploadedByRocketry Forum1476845074.462884.jpg

ImageUploadedByRocketry Forum1476845083.888681.jpg

I'll add holes to further secure the batteries with zip ties.
 
fyrfytr310 said:
OH NO!!!

Upon removal of the fin can, it became apparent that I didn't press down on the fin hard enough, or something, leaving a significant gap between the root and MMT on one fin.

View attachment 296487

Could I just fill it in with epoxy and no one would be the wiser? Yes. But why would I set aside prudent construction technique and risk the flight and everyone's safety. Sigh. I marked the fin position on the CRs and set off to cut the fin free. Fortunately there was enough gap that a Dremel cutoff wheel snuck in quite easily.

View attachment 296488

View attachment 296489

The remnant JB on the MMT was easily removed with a sharp knife and a Dremel grinding wheel cleaned up the fin nicely.

Round 2:

I mixed up a new batch of JB and reset the fin. Gap again! Upon closer inspection, I found a small obstruction on the forward side of the aft CR. Dremel to the rescue again and we are once again drying.

View attachment 296490

If I had not set out in the course of making the whole fin can removable for construction, I would have never seen this flaw and we could have had a seriously failed flight...
Click to expand...

Maybe when you sanded the motor tube you removed too much material?
 
fyrfytr310 said:
Good hit on the electronics sled this evening.

View attachment 303657

View attachment 303658

I'll add holes to further secure the batteries with zip ties.
Click to expand...

Man I hate to mention it now but those shurter switches have had problems and are no longer being used or sold by many in the rocket community . I do still have one rocket with them but will change over before I fly again. Personally I've had 2 failures with shurter switches.
You really want to move in a new direction on those switches.
 
I have to agree with Nick on the use of the Schurter switches, I hear more and more stories about their lack of reliability in this application. I had one fail on my L3 rocket but luckily I caught it during my pre-flight electronics testing. You might consider the new switches that Mike at Mac Performance Rocketry is selling. These are heavy duty 2 post push on/off switches that will fit in the same 1/2" hole. Looks like you have plenty of room for them. I would also suggest that you shrink wrap your connection after soldering it to the post.

https://shop.macperformancerocketry...products/copy-of-hardware?variant=30892630343

IMG_20160918_155253_012-1_1024x1024.jpg
 
Between Poker, Nick, and a note I found from Pondman advising caution with these switches, I'll look for something else. Not worth making the flight uncomfortably dangerous.

I'm intrigued by the push on/off switches. Anyone have documented success with them?
 
You want to be careful with push on/off buttons. Unless they're recessed or behind a panel, there's an unacceptably high probability that they will be accidentally turned on.
 
grandcross said:
You want to be careful with push on/off buttons. Unless they're recessed or behind a panel, there's an unacceptably high probability that they will be accidentally turned on.
Click to expand...

If I were to use these, they would be mounted on the sled in the same locations as the Schurters and they would be engaged through the equalization ports.
 
Good call - nice looking piece! For what it's worth I previously purchased several Schurters that I need to find another use for :).
 
fyrfytr310 said:
Between Poker, Nick, and a note I found from Pondman advising caution with these switches, I'll look for something else. Not worth making the flight uncomfortably dangerous.

I'm intrigued by the push on/off switches. Anyone have documented success with them?
Click to expand...

I haven't had a chance to try out the switches from MAC yet but I will work them into my next build. I ended up using heavy duty key switches on my L3 but the Binder Switches should work out great. Those have been used in 100's of flights and I haven't heard anything negative about them. Build is looking good, when do you plan on flying?
 
fyrfytr310 said:
Decided to go with what I have already proven to myself on many previous flights. I had a spare Binder arming switch so I ordered another one and will replaced the suspect components on arrival.

https://binderdesign.com/store/page6.html
Click to expand...

Good call. The Schurters represent an additional failure risk that is completely avoidable. The binder design switches are good. Heavy, but good.
 
I would love to find a Nov launch somewhere. Work travel might get in the way though.
 
Did an in-person review with my TAP.

We got weights on all component (save for a few recovery items I haven't procured). We also confirmed CG at 50" from the base (will shift forward based on aforementioned recovery components).

Discussed adding antizipper foam to harnesses as well as shear pin quantity, size and placement.

This is coming in lighter than I anticipated so my motor selection is probably going to change in the interest of finances.
 
Looks like I'll be flying on a M2500T. Still preliminary but here is a plot from my latest SIM.

ImageUploadedByRocketry Forum1477587089.767265.jpg
 
That looks like a great motor , almost an N, I planning flying that one day too since it's the same hardware as a 1939

- on mine I initially thought about a 5:1 - but instead went with a 7:1 and a good thing since my final weight was heavier so now am 5.4:1.

Weird that on my Thrustcurve it shows that max thrust is 3700Ns but on the Thrustcurve graph shows around 2900 Ns is max. Not that you will have any thrust issue with the Blue thunder.

Also you might check the Aerotech Open thread (post 1320) the 98mm grain bonding is now necessary on that motor.
 
Last edited:
Nick@JET said:
That looks like a great motor , almost an N, I planning flying that one day too since it's the same hardware as a 1939

- on mine I initially thought about a 5:1 - but instead went with a 7:1 and a good thing since my final weight was heavier so now am 5.4:1.

Weird that on my Thrustcurve it shows that max thrust is 3700Ns but on the Thrustcurve graph shows around 2900 Ns is max. Not that you will have any thrust issue with the Blue thunder.

Also you might check the Aerotech Open thread (post 1320) the 98mm grain bonding is now necessary on that motor.
Click to expand...

Thanks for the heads up. I'll check it out.
 
fyrfytr310 said:
Thanks for the heads up. I'll check it out.
Click to expand...

I have flown this motor without grain bonding and had no issues. However, if AT is recommending this, then you should plan on doing it. When you get to the point of grain-bonding, let's talk. I do this on all my EX motors and we can set up in my shop to do it before the launch.
 

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