RocketReviews.com - Semroc - Centurion

Brief:
This rocket is a retro-repro, 18mm, standard 4FNC rocket with baffle ejection and dual parachute recovery system.

Construction:
The balsa sheet was within the instructions and was broken in many places parallel to the grain. One fin was broken into 2 pieces, the other three were broken into three pieces each. Let me hasten to add, I am NOT blaming Semroc for this. This rocket was sitting near the bottom of a rather substantial pile of other level one rockets. I suspect that is was my own careless handling that caused this.

Since other reviewers have listed the individual parts, I will not do so again. Construction was supposed to begin with the traditional motor mount. For me, construction began with my attempts to repair the broken fins. Fortunately, all the breaks were very clean. I used thin CA and they were soon ready to go and probably stronger than before.

Will that done, all the parts were present and accounted for and I was ready to begin in earnest. That brings us back to the motor mount. It was a farily standard affair. The hook is set in the provided slit and taped into place. A thrust ring is glued into the forward end and the centering rings are glued into place.

Next up was assembly of the ejection baffle. This is the first baffle I have ever tried to build or use. It comes as a standard part of the kit. The two baffle rings are removed from their sheet and the hole are punched out. The forward baffle also has a small slit which is used to fasten the shock cord. The supplied cord is a length of sewing elastic. It is not particularly long but certainly servicable. I decided to use 2 feet of Kevlar® to attach to the baffle. This was not because I doubted the baffle's ability to work. I just like long recovery trains. I will use the elastic as well. semroc_centurion_baffle

The Kevlar® was fed through the hole and knotted a few times to prevent it from pulling through. The tail was then laid flat across the back of the baffle and glued down with yellow glue. I gave it a couple of coats.

Then there is the matter of gluing the baffles to the ends of the coupler tube. This was done with yellow glue as well. I was interested to see that the baffles sit on the shoulder of the coupler and not within it. This makes sense but I had always pictured in my mind that they sat within.

The rocket airframe consists of two tubes connected to each otehr by means of the coupler housing the baffle. Care must be taken so that the baffles are centered correctily and the coupler will actually fit into the BTs. Once they fit, it is an easy matter to glue the two sections together. Two things need to be remembered. The direction of the the baffle and therefore the shockcord matters. Also, the instructions suggest laying the assembled airframe down and rolling it around once it is assemble to make sure it is straight.

According to the instructions, the next step is to mount the fins. Since I wanted to use my Art Rose fin jig, I elected to install the motor mount first. The jig depends upon the motor mount to recieve the mandrel. Some glue was swabbed in, the mount pushed part of the way in, some more glue placed and the mount was slid home.

I need not have bothered with the jig. I did not set the screws properly and the result was an abomination. It will no doubt fly and is probably not too noticable from a distance but looking at the result makes me cringe. It reminds me of some of my worst effots as a kid.

Finishing:
Despite my disappointment with the fins, I plugged away at the Centurion. The rocket was filled and sealed with Elmer's FNF® and then sanded smooth. I then primed it with two coats of white and gave it another sanding.

The sanding was followed by 2 coats of gloss white which went down smoothly enough. When the white had a chance to dry, I masked the lower body from the coupling of the 2 BTs and sprayed the upper body with gloss black. I gave the upper body 2 coats as well.

When I peeled back the masking, I was both elated and disappointed. I was elated because, for the first time, I had gotten a perfect masking. There was no leakage at all and the change was crisp and professional. That bummed me out because it seemed wasted on a rocket whose fins I had hashed so badly.

The decals are a simple affair but they are very effective. They consisted of 2 Centurion logos and 4 red stripes. The Centurion logos went on just fine. The decal material is of good quality and I had no problems. The stripes were a bit different.

Two of the stripes are intended to be joined together to make one circuit about the BT just below the black paint. There is more than enough material to do so. The other two stripes are to be placed on either side of a single fin. They were long for the purpose and had to be trimmed to fit.

If I had my choice, the wrap around stripe would have been a single unit and the fin stripes would have been the right length to begin with. That may be picky but it is my opinion. The decals improved the look of the rocket marvelously.

Flight:
The recommended motors for this rocket are the A8-3, B6-4 and C6-5. I decided to start small as is my usual practice. I loaded up an A8-3. That was not the best of choices. I also added a bit of dog barf since this was my first experience with a baffle. It climbed to a startlingly low altitude, stopped and started to come down. About 20 feet up, the ejection charge went off but the chute did not have time to open. I got a nice little core sample but there was no real damage.

The second flight was on a B6-4. This was a good flight. It went up straight, the chute deployed at apogee and it came down gently. This time I tried it without any dog barf and the baffles worked fine.

The third flight was on a C6-5. This too was a good flight and recovery. It had a bit of weathercocking but landed near the pad.

Recovery:
This rocket should not be flown on an A motor... period. I should have been able to figure that out for myself. That being said, it does well on a B and very well on a C. The baffle works great and the rocket looks good... if you get the fins on right. I didn't, but it still flew well.

Summary:
This is a nice rocket. It looks good and is easy to build. It is fairly forgiving and fles great.

Flight Log

Date	Rocket Name	Motor(s)	Altitude	Notes
2007-05-20	Bill Eichelberger's Semroc Centurion	B6-4	-	Only one chute deployed, but landed in the veggies. Nice flight.
2007-05-20	Bill Eichelberger's Semroc Centurion	C6-5	-	Great flight and both chutes deployed.
2007-06-01	Chan Stevens's Semroc Centurion	C6-5	-
2007-06-23	Ron Wirth's Semroc Centurion	B6-4	-	First flight (no wadding). Went straight off the pad. One chute did not unfurl but it landed...
2007-08-05	George Beever's Semroc Centurion	C6-5	-	Scratchbuilt with SEMROC parts - about 2 months before they released the kit. Great flight.
2007-09-02	George Beever's Semroc Centurion	C6-5	-	Chute lost one shroud line but no damage.
2008-03-29	John Lee's Semroc Centurion	A8-3	-	low flight, chute deployed about 20 feet up and did not have time to open. Core sample without...
2008-03-29	John Lee's Semroc Centurion	B6-4	-	A perfect flight this time.
2008-03-29	John Lee's Semroc Centurion	C6-5	-	Slight weathercocking but great flight
2008-05-04	Chan Stevens's Semroc Centurion	C6-5	-
2008-08-01	George Beever's Semroc Centurion	C6-5	-	Great flight, last day at NARAM-50.
2008-09-27	John Lee's Semroc Centurion	B6-4	-	Perfect Flight
2008-09-27	John Lee's Semroc Centurion	C6-5	-	Perfect agaub
2009-02-14	John Lee's Semroc Centurion	A10-0/A8-3	-	Staged fine but underpowered sustainer. Arced over and hit ground. No damage.
2009-02-21	Lance Alligood's Semroc Centurion	B4-4	-	Excellent first flight. Slow & low. Had it angled on the pad nicely & it came back to within...
2009-02-21	Lance Alligood's Semroc Centurion	B4-4	-	Slow & low lift off. The winds had picked up slightly since the first flight & blew it back into...
2009-02-21	Lance Alligood's Semroc Centurion	B4-4	-	The up part was the same as previous flights. Angled it a little too well as it came back very...
2009-02-21	Lance Alligood's Semroc Centurion	C6-5	-	Nice zip off the pad & good altitude. The winds & a slightly long delay had it on the way down...
2009-05-02	Lance Alligood's Semroc Centurion	C6-5	-	Good flight with plenty of altitude. Cocked into the wind & landed in a bush at the edge of the...
2009-05-02	Lance Alligood's Semroc Centurion	C6-5	-	Up portion same as previous flight. Chute never opened though. Rocket bounced off the soft field...
2009-05-02	Hans "Chris" Michielssen's Semroc Centurion	B6-4	-	Clean flight, slow lift-off.
2009-05-06	Mark Grisco's Semroc Centurion	A10-0/C6-5	-	first flight. i used my booster-16. SUPER COOL!!! it staged at about 25 or 30 feet. the centurion...
2009-07-07	Mark Grisco's Semroc Centurion	A10-0/C6-3	-	used my booster 16. perfect staging at about 25 feet or so. sustainer weathercocked a little and...
2009-07-11	Duane Boldt's Semroc Centurion	A10-0T/C6-5	-	2 stage flight with Semroc Booster-16 add-on with a 13mm A10-0T motor. Cool flight with a slow...
2009-07-25	Duane Boldt's Semroc Centurion	A10-0T/C6-5	-	Nice!
2009-09-05	George Beever's Semroc Centurion	C6-7	-	Should have used a -5 delay. Still, a good flight!
2009-09-12	Mark Grisco's Semroc Centurion	A10-0/C6-5	-	weathercocked off the pad+i meant to use a 5 second delay and instead used a 7. slamed into the...
2010-04-03	Hans "Chris" Michielssen's Semroc Centurion	B6-4	-	Clean flight, should have gone with a C6-5. Only used one 12 chute, landed in puddle, had to shake...
2010-05-29	George Beever's Semroc Centurion	C6-5	-	Great flight.
2011-04-04	Hans "Chris" Michielssen's Semroc Centurion	Estes A8-3	75? feet	Low "lob" flight. Not worth it, wasted an engine. Parachute didn't have time to open, no damage on...
2011-06-07	Bill Eichelberger's Semroc Centurion	B6-2	-	Keychain camera flight. Drifted onto wires near the field and was rescued the following morning...
2011-06-28	Hans "Chris" Michielssen's Semroc Centurion	Estes B6-4	325' est. feet	This rocket and a B6-4 are a good match for this field. One of the two 12" parachutes was removed.
2011-07-18	Hans "Chris" Michielssen's Semroc Centurion	Estes B6-4	325' est. feet	Perfect big body rocket for this soccer field. With one of the two 12" parachutes removed it still...
2011-08-29	Hans "Chris" Michielssen's Semroc Centurion	Estes B6-4	325' est. feet	With the wind starting up, I removed one of the two 12" parachutes. Perfect flight and recovery.
2011-10-16	Hans "Chris" Michielssen's Semroc Centurion	Estes C6-5	650' est. feet	Good flight, a little drift in the 15 mph winds. No damage on recovery under two, 12" parachutes.
2011-10-25	Hans "Chris" Michielssen's Semroc Centurion	Estes B6-4	325' est. feet	Even with the baffle there was still a little charring on the single piece of "safety" wadding....
2011-11-25	Hans "Chris" Michielssen's Semroc Centurion	Estes B6-4	325' est. feet	I'd just refinished the Semroc CENTURION and knew it was time to add some new flight damage. With...
2012-01-15	Luke Wolski's Prisoner Transport Rocket	B6-4	-	Best flight in the world!
2012-02-29	Hans "Chris" Michielssen's Semroc Centurion	Estes B4-4	264' est. feet	B engines in this sized model are a good match for this field. Dual 12" parachute recovery.
2012-03-03	Hans "Chris" Michielssen's Semroc Centurion	A10-0/B6-4	35 feet	I used the ST-16 Booster unit from Semroc for the first time. At separation it was vertical. It...
2012-04-01	Hans "Chris" Michielssen's Semroc Centurion	Estes B6-4	325' est. feet	First launch of two with a B6-4 to 325' altitude, testing out a new engine retainer.
2012-04-01	Hans "Chris" Michielssen's Semroc Centurion	B6-4	325 feet	Second Centurion flight today with a B6-4 to an estimated 325' altitude. I was testing out a new...
2012-04-08	Hans "Chris" Michielssen's Semroc Centurion	Estes B6-4	325' est. feet	Again testing a new engine retention method. All worked well, dual 12" parachute recovery.

Semroc - Centurion

Flight Log

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