2015-04-04 - Will Ferry's Bumbl-B

Flight Log - 2015-04-04 - Will Ferry's Bumbl-B

During initial construction I managed to JB-Weld the motor retainer backwards (even after double-checking). Discarded original 36" tube and replaced with 48" tube and 54mm threaded slimline retainer.

Initial rocket length: 83.5"

First flight (2014-09-13, I215) resulted in ~1.5" zipper on lower BT due to ascent separation. BT cut 1.5" shorter. Renamed "Bumbl-B mk II".

mk II rocket length: 82"

Second flight (first as mk II, 2014-09-13, I65W-P) resulted in ~1" zipper on upper BT and ~15" zipper on lower BT due to failed drogue charge (bad e-match). Cut upper BT 1.25" shorter and lower BT another 15" shorter. Renamed "Bumbl-B mk III".

Lower BT had to be cut below the original hardpoint anchor as zipper ran down to the hardpoint. Replaced with Aero Pack M54E retainer (drilling 5 holes for motor ejection bypass). Upper and lower BTs epoxied together at coupler (no longer separates). No longer capable of carrying electronics other than inside nose cone.

mk III rocket length: 65.75"

Thirteenth flight (tenth as mk III, 2015-03-21, I245G-12) resulted in 2.6" zipper on lower BT due to late AT motor eject. BT cut 2.6" shorter. Renamed "Bumbl-B mk IV".

mk IV rocket length: 63.125"

Fourteenth flight (first as mk IV, 2015-04-04, I357T-12) resulted in significant airframe damage due to very early AT motor eject. Lower BT zippered down to coupler from mkIII repair. Additionally the Slimline motor retainer was crimped during landing, had to be hacksawed off rocket. Rocket finally rebuilt March 2016, with two new airframe sections and new avionics bay coupler to replace damaged piece and restore original dual-deploy design. AeroPack M54E used to replace original Supermount during mk III repair now used for motor retention. Renamed "Bumbl-B mk V", used name "Return of Bumbl-B" on first flight card but name was not announced.

mk V rocket length: 82"

Fifteenth flight (first as mk V, 2016-04-02, I225FJ-P) resulted in ~18" zipper of lower BT due to failed apogee chute deployment (36" chute stuck in airframe). New BT section zippered entire length, down to coupler from mk III and mk V repairs. Rocket is awaiting rebuild once again (mk VI).

Flight Date:	2015-04-04
Rocket Name:	Bumbl-B
Kit Name:	Giant Leap Rocketry - Firestorm-54 {Kit}
Flyer's Name:	Will Ferry
Motors:	I357-12
Expected Altitude:	2,999 Feet
Launch Site:	LUNAR - Snow Ranch
Actual Altitude:	1,763 Feet

Very early motor eject (RMS-EZ) resulting in severe damage to airframe.

Flew with AltimeterThree and AltimeterTwo, used more secure attachment this time (keychain ring), altimeters not lost during rough separation.

Flew with Eggtimer TRS @ 919MHz. Data downloaded from all 3 altimeters. Good visual on flight, but still used GPS coordinates to find in field.

Flew with U8 camera. Video quality not nearly as good as Mobius, which was destroyed in previous crash of dd.xls. In addition camera shifted during rough separation, obscuring vision during entire descent.

OpenRocket sim for flight suggested 11.5s optimal delay, with experience on all my AT delays being short I drilled the RMS-EZ delay from default 14s -2s to achieve a 12s nominal delay. The actual ejection event occurred at T+5.72s, 4.37s after burn-out. Rocket estimated ascent around 220 mph at ejection, which caused upper airframe to zipper all the way to the motor mount and then separate from the lower airframe.

During landing rocket apparently hit a rock such that Slimline retainer was crimped and threaded ring could no longer turn. Had to hacksaw through the retainer to free the 38mm casing aft closure.

First and final flight in the "mk IV" configuration. Remaining intact airframe starts at base of fincan (no remaining length to attach new retainer) and ends at damaged coupler just above shock cord mount. Previous "mk II" to "mk III" repairs replaced original supermount with Aero Pack M54E retainer, which provides option for retaining motors from the top. Plan is to replace upper airframe and return rocket to DD design, using M54E for motor retention. Undecided as to what future name of re-built rocket will be.

Stage	Motor(s)
1	I357T-14A

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