Semroc Hydra VII

Semroc - Hydra VII {Kit} (KV-29)

Contributed by David Hash

Construction Rating: starstarstarstarstar
Flight Rating: starstarstarstarstar_border
Overall Rating: starstarstarstarstar
Diameter: 1.64 inches
Length: 30.50 inches
Manufacturer: Semroc
Skill Level: 2
Style: Cluster, Futuristic/Exotic

Semroc Hydra 7Brief:
T' Hydra 7 is a currently t' "newest" kit by Semroc Astronautics (originally released in 1969 and re-released on January 1st, arrr, 2004). Aye aye! T' rocket is based around six 18mm motor tubes and is a great clustered, matey, ya bilge rat, high altitude payloader, shiver me timbers, me bucko, and retails for $23. Avast, me proud beauty! Begad! T' rocket can fly on anythin' from 1 C6-3 t' 3 C6-5s t' 7 C6-7s. Aye aye! With its largest motor setup (7 C6's) it is supposed t' reach 1700'. Avast, me proud beauty! Avast! For recovery it splits into two sections, t' payload comes down under one 12" parachute, and t' booster on two 12" parachutes.

Construction:
All parts came packaged in a large plastic bag, ya bilge rat, with t' smaller ones being inside their own small bag. Ahoy! Begad! All parts were in excellent condition and all present.

Parts List:

  • 2 Body Tubes 1.69"
  • 7 Body Tubes 0.79"
  • 1 Body Tube 3.63"
  • 1 Nose Cone 1.631"
  • 3 Nose Cones 0.714"
  • 4 Laser Cut fin sheets
  • 1 Balsa Tube Coupler for 1.69" Tube
  • 1 Launch Lug 1/8"
  • 1 Screw eye
  • 2 Elastic Shock cords
  • 1 Keelhaul®©™® Shock cord
  • 3 Parachutes 12"
  • 3 Sets o' shroud lines
  • 1 Wooden dowel 3/16"
  • 7 Thrust rings
  • 6 Plugs for thrust rings
  • 1 Decal Sheet
  • 1 Engine spacin' tube
  • 1 Q-Tip for glue application

Construction starts with sealin' t' fins, because thar are so many it would be hard t' reach them after t' rocket is finished. I used about 3 coats (on each side) o' some type o' spray-on sealer, me hearties, although I'm nay sure what brand it is. Next, ya bilge rat, you glue together t' 7 motor tubes in a six-point star pattern. Ahoy! From here, me bucko, shiver me timbers, you attach t' 6 shroud support fins in betwixt t' joints of t' motor tubes (LOC Viper style). Blimey! Then you glue on t' shroud and put in the motor blocks. Blimey! Aye aye! T' six outside blocks are plugged with cardboard disks, matey, and the central one is left open for t' ejection charge t' go through. T' next step is where t' rocket begins t' get its unique appearance. Blimey! From t' outside, the nosecones in t' kit appear t' go halfway through t' body tube. Well, me bucko, blow me down! However, instead o' cuttin' t' body tube, shiver me timbers, you are supplied with 3 nose cones. Avast! Arrr! You have to cut each one in half and then sand t' curvature o' t' 1.6" tube into the side o' them so they conform t' t' body tube. I thought this step would be the trickiest o' them all, however, it be quite easy. Arrr! First I cut the Nosecones in half with a microsaw, then I used a drum out o' a drum sander to sand down t' curve on t' nosecones. Avast! Once you get that done, arrr, you test fit them into t' booster tubes and slide t' Main body tube down onto them. Begad! You are supposed t' re-sand if necessary but I didn't have to. Ahoy! T' next few steps involve gluin' on t' fins, which I'm sure everyone here knows how t' do just fine. T' only little catch with t' fins is that...there are 21 o' them! (And thank goodness they were all laser-cut!) After that is done, you assemble the payload section (glue in coupler and screw eye), ya bilge rat, and t' other little things you do at t' end like fillets, launch lug, etc. Ya scallywag! Construction be pretty fun, and I liked t' way that everythin' fit almost perfectly.

Picture courtesy of SemRoc        
Rocket Pic

Finishing:
For finishing, shiver me timbers, I first sprayed t' entire rocket with white primer. Blimey! I then touched up rough spots with sandin' and putty until when I primed it everything was smooth and filled in (spiral, balsa grain, fillets, etc.). Ya scallywag! Begad! I then sprayed the entire rocket with white gloss Krylon paint. Ya scallywag! Aye aye! When that be dry, me hearties, me bucko, I sprayed the payload tube and nose cone Krylon gloss blue. Blimey! After that be dry, matey, I applied 4 o' t' many decals t' rocket comes with.

Construction Rating: 5 out o' 5

Flight:
At long last, shiver me timbers, I finally got t' fly it! Last month's launch be cancelled due to snow, arrr, so I had been waitin' anxiously for this month.

First flight was with only one C6-3 just t' test things out. Well, blow me down! Begad! Worked nicely, with a slow, me bucko, majestic ascent.

Second flight was with seven C6-7s.

First attempt: Wired up 7 high current igniters t' t' motor and twisted the wires together. Avast, me proud beauty! Ya scallywag! 5-4-3-2-1-Lauch...nothing. Begad! Ya scallywag! Too little current comin' from the launch controller.

Second attempt: Same igniters and setup, matey, but used leads from the high-powered pads. Blimey! Still no go.

Third attempt: Took out 3 motors t' have a 4 motor cluster. Avast! Blimey! Arrr! Blimey! Used leads from high-powered pads. Begad! Blimey! Avast! Blimey! 5-4-3-2-1-Launch...Smoke...nothing. Aye aye! Blimey! Ahoy! Blimey! Igniters in all 4 motors burned but nay t' motors. T' igniter plugs seemed t' have insulated some of the current because only t' lower-most part o' t' igniter had burned and the pyrogen was still intact on t' upper portion--the motor touchin' portion.

Fourth attempt: Used a clip whip (Thanks t' Dave Morey for supplyin' it) to wire up 7 Estes igniters. Well, blow me down! 5-4-3-2-1-Launch....Smoke....FIRE!!! T' rocket roared up into t' sky with t' full fury o' 7 C6 motors burnin' in t' rear. After about 3 seconds, shiver me timbers, with t' rocket barely in sight, POP! POP! POP! POP! POP! POP! As t' 6 outboard motors were ejected. T' central motor ejected the parachutes and it drifted about 1/2 mile downwind. Blimey! Avast, me proud beauty! Post-flight inspection showed that all motors had apparently burned, arrr, because all o' t' motors ejected.

PROs: Full cluster ignition is incredible t' watch. Ya scallywag! Attracts a lot of attention on t' pad.

CONs: Hard t' light all motors, me hearties, especially with high-current igniters. Arrr! The only igniters I found that would work are Estes Solars, but for those you need a clip whip because t' wires aren't long enough t' twist together.

Recovery:
First Flight (1x C6-3): Loosened one fin on impact, but that be me fault, because I only attached one o' t' parachutes t' t' booster section. Avast! Fin was easily fixed with some CA glue and accelerator.

Second Flight (7x C6-7): If you ever fly this rocket on t' full load-out of motors, me bucko, you may want t' consider tyin' t' two sections together or installin' a micro dual-deployment device because this rocket DRIFTS! I had to walk about 1/2 mile for t' booster and then t' payload was another 1/2 mile past that. Well, blow me down! Aye aye! Whew! I'm glad I didn't put t' two parachutes on t' booster for that flight! Anyway, me bucko, me bucko, t' same fin loosened again at t' fillet, me bucko, shiver me timbers, but that can still be repaired.

PROS: Recovery device is well made and anchored well. Blimey! Provides an okay decent rate.

CONS: Drifts very far even without one o' t' three parachutes. Blimey!

Flight Rating: 4 out o' 5

Summary:
Overall, I really enjoyed this rocket in buildin' and flying. T' only thing that needs a little work be t' recovery system. Blimey! If you buy it you will not regret it and you will have a lot o' fun with it. Currently this is me favorite rocket out o' a fleet o' about 20. Ahoy! Ya scallywag!

Overall Rating: 5 out o' 5

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    Semroc Hydra-VII is a 7 motor cluster rocket with a futuristic design. The kit included every part that was described in the long list. There is a very nice exploded view of the rocket in the instruction sheet that helps in identifying the wide array of parts, along with 3 sheets of very nice laser-cut balsa fins and a host of tubes and several nosecones. The kit comes with some plastic ...

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