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Mad City Flyers 02-04-2017 03:33 PM

Wildman Eagle Claw 4 Winter Project
2 Attachment(s)
Hi All,

Hopefully you're having fun in your workshop assembling rockets for this spring and summer!!

After successfully achieving our L2 cert last year Nate and I are going bigger and more complicated prior to an L3 cert attempt.

We chose the Widman Eagle Claw 4 as a great kit to test our building techniques and to add more complex electronics.

With the 54mm MMT we hope to go as big as an Aerotech L1000!

Here's what we are trying with this build:
  • Redundant dual altimeter triggered ejection charges
  • Additive aerospace SMART sled
  • Trackimo tracker
  • Additive aerospace external shroud for camera
  • Mobius 1080HD camera


Mad City Flyers 02-04-2017 03:41 PM

Build Progress
3 Attachment(s)
Hi All,

Only snafu with the kit was a tail cone that was about 4 inches too long. A quick email to Tim and Jackie resulted in their typical friendly and prompt reply and shipment of the correct sized tail cone.

This kit is interesting as it has a 36" MMT that needs to run from the bottom all the way up to beyond the front fins. We had to Dremel out the fin slots a bit to get a perfect fit. Also had to Dremel out a portion of the connector tube that links the tail cone to the booster section. There was some overlap.

We attached an Aeropak retainer to the bottom of the MMT followed by 3 centering rings.

For the recovery cord we've been using nylon strap and using an awl to sew our own loops. After making some notches in the forward centering rings we ran the nylon recovery strap under and epoxied against the MMT.


Mad City Flyers 02-04-2017 03:54 PM

Build Progress 2
5 Attachment(s)
Hi All,

Forgot to mention that before actually setting the forward centering rings and recovery strap we fixed the MMT into the tail cone. We fixed the Aeropak retainer and one centering ring to the MMT and then epoxied it into the tailbone. Epoxied the tail cone connector in place, used the Dremel to widen the fin slots and then moved on to fixing the fins.

We then got to use our new toy: Gorilla Guillotine Fin Jig!!! Wow this fin jig is awesome and easy to use... worth every penny. To keep everything in alignment we

We used Great Planes 30 minutes epoxy and ran internal fillets prior to foaming the fin can with Public Missles Ltd. Adjustable Density Foam.

We played around with the foam as instructed filling solo cups prior to foaming the tail cone. We decided to not add any water just a 1:1 mix of parts A and B. It took a couple of additions, waiting for it to solidify between each pour. The hard part was digging out the overage to make sure the centering ring would sit down evenly on the forward edges of the fins.

This was our first time foaming a fin can and it seemed to work out well. Not sure I would be comfortable using this technique on anything but fiberglass.


Mad City Flyers 02-04-2017 04:09 PM

Build Progress 3
2 Attachment(s)
Hi All,

Ok, with the tail cone fins fixed and foamed it was on to the booster fins. We had a couple of assembly challenges:
  • Rail button placement
  • Alignment of tail cone fins with forward fins
  • Length of the rocket relative to the fin jig
  • How to set internal fillets on the forward fins?

I'm sure there's different ways to solve these build issues. Here's how we tackled them:

We first fit the tail cone and booster sections together but not completely. There was enough room in the gap between the two sections to fix a 1515 rail button using a T nut embedded in wood through the tube wall. We did not epoxy the forward centering rings at this time.

When we fixed the tail cone fins using the fin jig we had also dry fit the forward fins in the booster section so they would be aligned. We placed tape across the seam between the tail cone and booster section which was then cut at the seam with a razor blade. By numbering each of the 3 sections of tape we had a way of realigning the airframe tubes for the final assembly.

We then ran a thin layer of epoxy around the tail cone connector tube pushed the sections together and made sure to align the tape markings. We placed the airframe back in the fin jig, dry fit a forward fin and clamped everything in place to ensure a straight and tight fit.

Because we had to widen the forward fin slots a space was left to run epoxy along the centering rings and airframe wall. So, we were able to make internal epoxy fillets without any additional drilling of holes.


Mad City Flyers 02-04-2017 04:23 PM

Build Progress 4
4 Attachment(s)
Hi All,

So the double fin set was not a perfect fit even for the Gorilla Guillotine fin jig, but we made it work.

After setting all of the forward fins it was time for external fillets.

I must say that the fin jig was amazing and the alignment of the tail cone and booster fins appears perfect. I guess will find out when we launch it!

For this bird we went back to our prior method of making external fillets:

We use some heavy grit sandpaper (80-100) to roughen up the airframe and fin areas then use 3M painters tape to mask off the fillet.
  • Great Planes 30 minute epoxy
  • West systems fiberglass
  • Phenolic microballons
  • Formula that seems to work for us is 7.5ml resin, 7.5ml hardner, 1 teaspoon fiberglass, 1 teaspoon micro ballons

Epoxy mixture is poured into the fillet area and then smoothed using a piece of 1" PVC soaked in rubbing alcohol. We only allow it to set about 5-10 minutes before pulling off the tape and then smoothing the epoxy with a gloved finger soaked in rubbing alcohol.

Using this technique we were able to get 4 fillets done in about 30 minutes and all 12 cast in 3 days.

The next step is obviously the dreaded sanding. We like to use the 3M flexible 150 and 320 grit sand paper. After fairly aggressive sanding to smooth down the edges we apply a generous amount of Elmers color changing wood filler. The wood filler helps to fill in those gaps and imperfections and is easy to work with. After letting the wood filler set overnight it was lots more sanding to take the filler down to almost nothing.

Cleaned up the booster/tail cone section with a wipe down using rubbing alcohol soaked paper towels and then set it aside to wait for painting weather.........


Mad City Flyers 02-04-2017 04:31 PM

Build Progress 5 - AV Bay
1 Attachment(s)
Hi All,

With the tail cone/booster section assembled we moved on to the AV Bay.

Additive aerospace SMART sled

Perfectflite CF altimeter

Missleworks RRC2+ altimeter

Dual rotary switches

Dual DogHouse Rocketry ejection charge cannisters

I'll post some additional pics when we figure out how to anchor the Trackimo tracker.



Rex R 02-04-2017 05:54 PM

a power sander works well for sanding FG and saves your arm :).

Mad City Flyers 02-04-2017 07:38 PM

Hi Rex,

I haven't found a power sander that can safely get into the fillets. I have tried wrapping the SP around a 6-8" piece of PVC. A little soreness reminds you that you put some effort into the job.

Hope your winter is going well.


Mad City Flyers 02-13-2017 08:31 PM

Build Progress 6 - Complete load Cg test
5 Attachment(s)
Hi All,

Aren't you glad we don't live on the East coast right now!!!!

So here's what got done this last couple of weeks:
  • Added the forward rail button
  • Added about 150g of steel shot to the nose cone tip
  • Epoxied the coupler to the nose cone
  • Drilled out vent holes and the holes to attach the payload section to the AV Bay
  • Test mounted the camera shroud to the payload section

So with pretty much all the build elements done it was time to load up the bird with all recovery gear and a K540M motor in a 54mm/1706 case and test for Cg.

The attached pics show the rocket balancing at the Cg, which turned out to match almost exactly where the OpenRocket simulation estimated the Cg. With the K540M motor it results in about 1.4 calibers of stability. When we move up to a 54mm/2560 motor we'll lose a little and might have to add a little more nose weight.

So now we just wait like everybody else for the 50 degree days when we can start painting in the garage and then land testing the ejection system.

Looking forward to the Bong!!!


Matt and Nate

tim_cub 02-14-2017 09:39 AM

1 Attachment(s)
Hey matt/nate, nice rocket. I built the same about 2 years ago. Mine also came with a long tail cone but I opted to keep it and add a longer MMT & of course Tim sent me a new one immediately.
Biggest motor I have flown in it so far was an L990.
I see you added nose weight. Mine didnt need any - it's very stable without it.!

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