Concept 200 build. Fiberglass 8 inch

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Conway Stevens

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Decided i wanted to add a larger body rocket to my fleet so picked up a Concept 200 and modified it a little. Will also be building a second booster with 6 inch motor tube capable of up to a P motor. But for now this is the 98mm motor. Plan to fly it first weekend of June and Northern Colorado Rocketry Mile High Mayhem event. Here are the parts ariving. Much bigger then the 3 inch 4 inch and my 6 inch L3 booster. Booster section 60 inches tall. Upper section is now 48 inches from 33. Nose cone is 5:1 Ogive. About 42 inches. Also just got the 98mm 15360 AT case. Plus picked up a couple Ns. The N3300 will be for this flight. In the Redline formulation.
 

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Conway Stevens

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Was able to get the nosecone coupler set in place. Got the upper centering ring and mid centering ring in place to the motor tube. U bolts in the upper double ring. Also will be tying onto the forward closure as added strength. Harness ties into a super duty swivel with tubular kevlar harness. Got the firsr fin set into place and ligned up. Will let it cure and set the next one
 

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Conway Stevens

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More progress on the 8 inch Concept 200
All fins in place, all fillets are done internally and externally.
Nose cone bulk plate fitted and glued in place, nose cone tracking bay built and set into bulk plate. Nose cone recovery attachment set.
Just have to fit, set and glue the aft centering ring then fit the thrust plate.
 

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Tim51

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Getting the booster assembly finished up.
Following along in watch 'n' learn mode here because I've never built a FWFG rocket. I didn't realise foaming the fin can was necessary on such a build - I thought it was more a thing for plastic and cardboard airframes. What does the foam add?
 

roytyson

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Getting the booster assembly finished up.
What are your reasons for internal fillets and foam?
Also, where did you get the thrust plate?
Did you all thread the centering rings together?
I have the same rocket to start on this fall, looks good so far.
 

Conway Stevens

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Following along in watch 'n' learn mode here because I've never built a FWFG rocket. I didn't realise foaming the fin can was necessary on such a build - I thought it was more a thing for plastic and cardboard airframes. What does the foam add?
Its not really "necessary" but with this particular foam its light weight. So its not adding a bunch of weight. Just bonding and dampening strength to the fin can.

I wanted this build to be strong. But i wanted to keep the weight down. Its a big heavy airframe. I was able to use less epoxy on the fillets. By no means are the fillets weak. But the epoxy is heavier than the foam. By adding the foam and utilizing a thrust plate i was able to gain better strength in the fin can with less stress on the fins at the attachment points. In the end i feel i gained better strength, lower weight, for both boost and recovery.

I have actually weighed out the whole rocket with everything except the motor and bp charges as well as with motor. The rocket comes in right at 55-56lbs complete no motor. On the pad ready to fly with a N3300 case and propellant the whole rocket should be 82-83bs. Recovery weight will be right around 66lbs. The foam only added 2 lbs to the total weight after it was added. So for a rocket this size. Not a substantial weight gain but alot more strenth and dampening in the fin can for higher thrust on the fins.

I have built other large builds using the same techniques and they have always worked well.

Posting below a complete summary of weights, and predictions of the flight.
 

Conway Stevens

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What are your reasons for internal fillets and foam?
Also, where did you get the thrust plate?
Did you all thread the centering rings together?
I have the same rocket to start on this fall, looks good so far.
See my reasons above for fillets and foam. btw not all epoxies are created equally. This is why i also use Aeropoxy. Its extreme strength and light weight in comparison to others. As well as its thickness and ability to hold shape without fillers for the fillets.

I had the thrust plate custom machined by a good friend. Its 3/8 thick T6061 aluminum. It has lightening points that dont affect strength or stress.

I NEVER Use all thread on any fin can personally i find it to add way to much weight and really if you build the fin can correctly it will be plenty strong enough. My recovery has 3 points of attachment. 2 at the forward centering ring. And the 3rd at the forward closure of the motor. So the thrust plate all the way through the body tube, all 3 centering rings will be engaged in the recovery. No need for all thread ever if designed correctly. I personally like to keep the weight down.
 

Conway Stevens

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Base rocket weight after construction with everything except motor and charges.

55-56lbs

Spent motor case weight no propellant
10 -11 lbs

Recovery weight
66lbs

Motor weight before launch
26lbs


Pad weight of rocket before launch
82-83 lbs.


Motor N3300R
Burn time 4.5 seconds
Peak thrust to weight ratio
8.5:1

Lift off
.05 seconds

Stable in
62.5 inches

Predicted altitude
9500ft

Seconds to apogee
24

Burn out at
2372 ft

Predicted max speed
602 mph

Acceleration gs
9.0 g forces


Recovery under drouge
122ft/s

Recovery under main
18ft/s
 

roytyson

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See my reasons above for fillets and foam. btw not all epoxies are created equally. This is why i also use Aeropoxy. Its extreme strength and light weight in comparison to others. As well as its thickness and ability to hold shape without fillers for the fillets.

I had the thrust plate custom machined by a good friend. Its 3/8 thick T6061 aluminum. It has lightening points that dont affect strength or stress.

I NEVER Use all thread on any fin can personally i find it to add way to much weight and really if you build the fin can correctly it will be plenty strong enough. My recovery has 3 points of attachment. 2 at the forward centering ring. And the 3rd at the forward closure of the motor. So the thrust plate all the way through the body tube, all 3 centering rings will be engaged in the recovery. No need for all thread ever if designed correctly. I personally like to keep the weight down.
Thanks for the feedback. I would be interested in seeing a harness with the three attachment point. Great work!
 

Conway Stevens

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Thanks for taking the time to explain. The dampening benefits of foaming makes sense, and, as you say, with relatively little weight gain.
As it expands it bonds to all the surfaces just like epoxy bonds. So its attached all the way around the inside of the airframe, the centering rings, the fins, the motor tube...etc. as it cures it becomes stiff and rigid. Very hard. This bond is excellent for assisting in fin attachment, attaching the motor tube and centering rings to the body tube. It gives added strength for the recovery. For flight it helps dampening the flutter of fins.
 
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Conway Stevens

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Thanks for the feedback. I would be interested in seeing a harness with the three attachment point. Great work!
I will get a picture. The 3 points attach to a large swivel. That then attaches to the drouge harness
 
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ZEDL1

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I've looked twice but may still have missed the detail. What type/brand of foam did you use?
Thank you.
Jim
 

Conway Stevens

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Some more progress.
 

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ZEDL1

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You do very pretty, meant from me as a compliment, and well thought out work Sir, and after a great many years in our hobby/obsession, I'm not easily impressed...
 

Conway Stevens

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You do very pretty, meant from me as a compliment, and well thought out work Sir, and after a great many years in our hobby/obsession, I'm not easily impressed...
Thank you very much Jim. Taken as a extremely large compliment.

Only about 2 weeks till launch. Hoping to ground test tomorrow. Then wrap of the little things and paint.
 

Conway Stevens

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Getting the electronics laid out. The Avbay is held together with 3 pieces of all thread. Primary altimeter is a Missleworks RRC2L. Set to apogee deployment of the drouge and 900ft the main. The backup/Redundant altimeter is a Missleworks RRC3X sport. Drouge set to 1 second after apogee and main set at 800ft.

Power is supplied by 2 turnigy 2S 7.4v 300mah batteries. Power control is set up with 2 circuit board style Missleworks screw switches held to the Avbay coupler with Additive Aerospace switch holders. Then to 2 Eggtimer mini wifi switches. The component holders are 3d printed from SDR for mounting Altimeters, battery holders and wifi holders. The wiring ferrerals are binder rocketry. The pass through connectors are LabRat Rocketry. Ejection charges are made from potted pvc tube.

Tracking is 2 different trackers. The Featherweight tracker is used for voice call out/reporting of the launch as it reports altitude and events, as well as speed and recovery status vocally while under flight. It also data logs rhe flight that can be overlaid to maps. Along with the full data from the altimeters. The second tracker is the Apogee simple tracker. Primarily for locating the rocket. With the Featherweight as back up duty.
 

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