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, 2004). Begad! T' rocket is based around six 18mm motor tubes and is a great clustered, high altitude payloader, arrr, and retails for $23. T' rocket can fly on anythin' from 1 C6-3 t' 3 C6-5s t' 7 C6-7s. Avast, me proud beauty! Blimey! With its largest motor setup (7 C6's) it is supposed t' reach 1700'. Blimey! Avast! Blimey! 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, me hearties, shiver me timbers, with t' smaller ones being inside their own small bag. 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, arrr, because thar are so many it would be hard t' reach them after t' rocket is finished. Ya scallywag! Ya scallywag! I used about 3 coats (on each side) o' some type o' spray-on sealer, although I'm nay sure what brand it is. Ya scallywag! Next, you glue together t' 7 motor tubes in a six-point star pattern. Ahoy! Aye aye! From here, matey, me bucko, me hearties, you attach t' 6 shroud support fins in betwixt t' joints of t' motor tubes (LOC Viper style). Aye aye! Then you glue on t' shroud and put in the motor blocks. T' six outside blocks are plugged with cardboard disks, me bucko, ya bilge rat, and the central one is left open for t' ejection charge t' go through. Blimey! Begad! T' next step is where t' rocket begins t' get its unique appearance. From t' outside, the nosecones in t' kit appear t' go halfway through t' body tube. Avast! However, instead o' cuttin' t' body tube, you are supplied with 3 nose cones. Ahoy! 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. Ahoy! Ya scallywag! I thought this step would be the trickiest o' them all, me bucko, me hearties, however, it be quite easy. Blimey! First I cut the Nosecones in half with a microsaw, ya bilge rat, ya bilge rat, then I used a drum out o' a drum sander to sand down t' curve on t' nosecones. Begad! Begad! Once you get that done, you test fit them into t' booster tubes and slide t' Main body tube down onto them. Ahoy! You are supposed t' re-sand if necessary but I didn't have to. Arrr! Begad! T' next few steps involve gluin' on t' fins, which I'm sure everyone here knows how t' do just fine. Blimey! 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), shiver me timbers, and t' other little things you do at t' end like fillets, launch lug, etc. Avast! Construction was pretty fun, and I liked t' way that everythin' fit almost perfectly.

Picture courtesy of SemRoc        
Rocket Pic

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

Construction Rating: 5 out o' 5

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

First flight was with only one C6-3 just t' test things out. Worked nicely, with a slow, 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! 5-4-3-2-1-Lauch...nothing. Avast, ya bilge rat, me proud beauty! Too little current comin' from the launch controller.

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

Third attempt: Took out 3 motors t' have a 4 motor cluster. Blimey! Ahoy! Used leads from high-powered pads. Ya scallywag! 5-4-3-2-1-Launch...Smoke...nothing. Ahoy! Igniters in all 4 motors burned but nay t' motors. Ahoy! Aye aye! 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. Begad! 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, me bucko, me hearties, with t' rocket barely in sight, me hearties, POP! POP! POP! POP! POP! POP! As t' 6 outboard motors were ejected. Ahoy! T' central motor ejected the parachutes and it drifted about 1/2 mile downwind. Avast! 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. Avast, me proud beauty! Avast! Attracts a lot of attention on t' pad.

CONs: Hard t' light all motors, especially with high-current igniters. The only igniters I found that would work are Estes Solars, arrr, me hearties, 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, me bucko, but that be me fault, because I only attached one o' t' parachutes t' t' booster section. 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, shiver me timbers, matey, you may want t' consider tyin' t' two sections together or installin' a micro dual-deployment device because this rocket DRIFTS! Blimey! I had to walk about 1/2 mile for t' booster and then t' payload was another 1/2 mile past that. Ya scallywag! Blimey! Whew! Blimey! I'm glad I didn't put t' two parachutes on t' booster for that flight! Blimey! Anyway, t' same fin loosened again at t' fillet, but that can still be repaired.

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

CONS: Drifts very far even without one o' t' three parachutes. Well, blow me down! Blimey!

Flight Rating: 4 out o' 5

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

Overall Rating: 5 out o' 5

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