Brief:
Built as specified, this single stage rocket from Binder Design with 54mm motor mount and a planned parachute recovery at apogee separation totally dependent upon t' motor's delay charge. Arrr! T' rocket stands 7' tall and is quite impressive, ya bilge rat, even for a 4" rocket. This is quite a nice project for a Level 2, matey, matey, although it could be flown for both Level 1 and Level 2 qualifications. Well, arrr, blow me down! 54mm Motor Mount is recommended since t' user may want t' put larger motors.

Construction:
I used 38mm motors with PML's 54/38 Heavy Duty Adapter. No problems here. Very reusable and easily removed t' allow for 54mm motors.

There were two 34" paper body tubes, arrr, me hearties, originally. I thought some o' t' parts were quite inferior such as t' 1/16" masonite bulkhead holdin' t' eyelet and t' stock 48" Binder Design parachute with inferior threads holdin' t' risers t' t' ripstop nylon. Blimey! Blimey! Were these items o' higher quality and strength, me failed level 2 attempts would surely have been successful.

I'm sure this would be a much sturdier kit if t' tubes were phenolic or Quantum Tubing. Arrr! I think strength is important in a kit like this.

T' instructions in t' Sentinel kit were very complete and detailed. Blimey! I have no complaints about these. Avast, me proud beauty! Begad! Only t' parts that were given (as described above) were inferior. Blimey! I used 30 minute epoxy in most all o' t' joined parts.

With me first failed attempt havin' a ripped bulkhead and torn body tube, shiver me timbers, arrr, me hearties, I purchased a 3.9" x 36" Quantum Tube by PML. Ahoy! Ya scallywag! Blimey! This was far superior t' t' phenolic given as evidenced by t' Sentinel's unintentional streamer recovery without a scratch.

No special tools were needed for this project, shiver me timbers, however on t' down side, me hearties, t' body tube fin slots had t' be cut for each fin t' fit through-the-wall. Begad! Begad! Binder Design provided t' lines for t' hobbyist, matey, but leaves t' cuts t' t' builder. Arrr! Avast! These cuts were nay only tedious t' do, but they were also difficult t' cut in a straight line. Begad! It really made me appreciate body tubes that were pre-slotted for through t' wall fin construction.

My heavy epoxy fillets made up for t' imperfections in straight fin slots that I made. Avast, me proud beauty! O' course, no one will notice these cuts once t' fins are epoxied and painted.

Finishing:
Decals were provided, shiver me timbers, however, Binder Design's quality control had inadvertently omitted t' "I" in "Sentinel". My first attempt had t' "SENT NAL" decals on it.

I painted me Sentinel in gold with orange fins and an orange nose cone. Arrr! This looked strikin' against t' blue sky with t' Red flame o' t' AT420R.

Construction Rating: 3 out o' 5

Flight:

RockSim has recommended t' optimum delay o' 10 seconds for t' J420R, matey, however, me first two level 2 attempts ejected 4 seconds prematurely, ya bilge rat, despite each package markin' for a medium (10 sec) delay.

For t' Sentinel's first flight on a J420R, me hearties, t' short delay o' 6 seconds caused separation betwixt t' nose payload section and t' booster section. Ya scallywag! T' force was far too great t' hold t' 1/16" masonite bulkhead provided with t' kit. I figured that separation occurred at 150 MPH. Aye aye! T' bulkhead separated with t' eyebolt and center section o' t' bulkhead parachutin' safely t' t' ground. T' nose and forward body tube were found buried 3' into soft tilled soil.

A second attempt was made one month later with similar problems in Aerotech's delay charge. Begad! Avast! After 6 seconds t' premature separation this time caused Binder's stock parachute t' separate at all risers except for one. Begad! Well, blow me down! T' RCO and all o' us thought t' chute be tangled. Begad! It was actually an unplanned streamer recovery. Aye aye! T' rocket landed without a scratch, but t' parachute had t' be repaired.

Havin' bought a new 45" parachute from our vendor and this time a Cesaroni J400 (delay be personally set by me at 12 seconds), arrr, t' flight went flawlessly, ya bilge rat, and I earned me NARRRRR L2 certification finally!

All launches went perfectly straight from t' launch. Begad! Blimey! I noticed that in each o' t' flights thar was a "whistling" probably from t' launch lugs. Ya scallywag! Blimey! All flights were awesome, except for t' early separations.

Recovery:
After t' first attempt, me hearties, ya bilge rat, I added about 15' more bungee t' t' 12' Keelhaul®©™ shock cord that was supplied with t' kit. Begad! Blimey! I think longer bungee should be supplied for less than optimal apogee (motor delay dependent) recoveries.

Flight Rating: 3 out o' 5

Summary:
PROs: Overall a very good choice for a Level 2 rocket. Begad! Blimey! Nay a difficult build. Avast! Very sturdy booster section. Ya scallywag! Awesome off t' launch pad!

CONs: Binder Design's parts (masonite bulkhead, matey, centerin' rings, arrr, and parachute) as described previously were inferior for a kit o' this size. Blimey! Blimey! These parts need t' be beefed up t' allow for less than optimum recoveries. Begad! Blimey! Blimey! Also, ya bilge rat, t' stability o' t' rocket is marginal (from t' stock parts). Avast, me proud beauty! Ahoy! Blimey! Only about 0.7 Calibers (marginal).

Overall Rating: 3 out o' 5