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  #1  
Old 08-01-2017, 03:34 PM
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rosko_racer rosko_racer is offline
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Default EAC Firecat

Back on the saddle on another scratch build, this time the Estes Aerospace Club Firecat, Kit #0821. The EAC Firecat, only sold to members of the EAC, was a kitbash of the old Honest John and the Bandit, which combined to make a cool looking scale-like drone.

I always loved this designed and back in 2009 I built a 1:1 scale of it. Not having the BT-48 for the scram jet, I had to improvise and make my own. It flies great. Sorry, no pad or flight pictures.
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  #2  
Old 08-01-2017, 03:47 PM
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Default Only EAC Firecat Build Thread on YORF

I searched but could not find a build thread on this model. This time I am doing an upscale, not by much, of the original EAC Firecat. Got hold of a NC for the Estes Expedition. Based on a BT-55, the upscale factor is 1:1.352. Not much bigger but still an upscale.

Oh... I forgot to mention that the decals for my first EAC Firecat were printed on an ALPs printer...

This is where I am so far...
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  #3  
Old 08-01-2017, 07:20 PM
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Very nice! I have always loved that design.
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  #4  
Old 08-02-2017, 07:12 AM
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Tried to roll my own body tube for the ram jet but I did not liked much how it turned out. So I decided to use a piece of BT-55 for it. And as always, I use the latest technology (aka whatever is around to help me) to keep the fins in place while the glue was setting. Meanwhile I put together the 18mm MM. I thought about putting a 24mm MM but simulations put it at over 700' with a C6. I like to get my rockets back after each flight...

After marking the guide lines on the BT I sanded the areas where the fins would attach to give some "bite" to the wood glue joints and fillets. Also punctured some small holes through the BT and squeezed some extra glue through them to have some glue "rivets" for the fins. I am not sure if this would make the bond between the BT and the fins stronger. I have seen it used on other builds and I have actually seen that when this technique is used it does create some sort of glue "rivet"... Use the double glue joint technique to attach the fins... still have to do the dorsal fin...
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  #5  
Old 08-02-2017, 07:19 AM
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Default Glue Rivets

To explain how I did the "glue rivets"... After sanding the fin joint area I used a pin to start the holes, then used a round diamond file to make them a little bigger. Afterwards I used the flat diamond file to sand over the holes to level that area of the BT... Hope you can see some of the progress on the picture. Once I glue the dorsal fin I will take a picture of the inside of the BT to see show how this works.

I was able to glue the fins before going to bed last night. Checked out the fins this morning and they are strongly attached to the BT.
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Last edited by rosko_racer : 08-02-2017 at 08:04 PM.
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  #6  
Old 08-02-2017, 07:00 PM
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Default Trucking Along...

Got some more done today, working on the dorsal fin and the antenna. Knowing that (at least on my 1:1 Firecat) the antenna is the most fragile part, I wanted to make something that it would stand some punishment. Made mine with coffee stirrers. Cut, glued, sanded, some more cutting, and I got what you see here. The two outer support legs go thru the BT and are secured on the inside with epoxy.
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Last edited by rosko_racer : 08-02-2017 at 08:04 PM.
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  #7  
Old 08-02-2017, 07:11 PM
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Here's the EAC Firecat. I think it is coming along nicely. Gonna let it rest for 24 hours to ensure all the glue is cured to then apply some thin epoxy fillets. I like epoxy fillets as they always come out smooth... a pain in the rear to apply (gotta wait the minimum amount of time to cure before you do the next one) but the results enhance the overall appearance of the rocket.

Thinking about placing label paper over the fin before applying the epoxy fillets. I have done it before and the results are not so bad. Helps with covering the wood grain, and it is said the paper reinforces the fins.
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  #8  
Old 08-02-2017, 07:38 PM
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Default EAC Firecat ROCSIM files

I created the 1:1 scale EAC Firecat sim file based on the rocket I built many moons ago. Then I upscaled it by factor 1.352 to get it as close to the BT-55 version as I could. I rounded up a few measurements. The 1:1 scale file does not have a NC but the upscale does, a different NC because I am lazy. I changed the parameters to the NC to closely match the plastic NC I have. That plastic NC is the reason why the CG is very forward from the CP. The CG in the sim does match the one built.

Find attached the rkt files. If anyone can improve on them, go ahead and share.

I think this upscale is the right size for this rocket on a 18mm motor.
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Name:  EAC Firecat ROCSIM.jpg
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File Type: rkt EAC Firecat BT-55 Upscale.rkt (91.5 KB, 15 views)
File Type: rkt EAC Firecat 1 to 1 scale.rkt (38.7 KB, 15 views)
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CAT
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Last edited by rosko_racer : 08-02-2017 at 08:01 PM.
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  #9  
Old 08-02-2017, 08:31 PM
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neil_w neil_w is offline
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Quote:
Originally Posted by rosko_racer
Thinking about placing label paper over the fin before applying the epoxy fillets. I have done it before and the results are not so bad. Helps with covering the wood grain, and it is said the paper reinforces the fins.

I label paper all my fins these days but always before assembly. Not quite sure I can imagine doing it to the fully built model. Have you done it that way before?
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  #10  
Old 08-02-2017, 09:04 PM
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Quote:
Originally Posted by neil_w
I label paper all my fins these days but always before assembly. Not quite sure I can imagine doing it to the fully built model. Have you done it that way before?



Yes, I have done it before. But it is more difficult for sure. A sharp X-Acto Knife is your best friend... it will just take longer.
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