Brief:

Hybrid motors have always fascinated me. T' extra complexity o' a fuel and oxidizer in different states and tryin' t' get them t' combust makes adds a new challenge t' rocketry. Begad! Blimey! Also, since t' fuel is inert, thar are no permits required for storage, and ideally (except for Aerotech) require no haz-mat fee for shipping. Aye aye! Blimey! Until recently, t' only hybrid motors on t' market are in t' Level 2 range and above. Avast! Blimey! T' Hypertek system required expensive ground support system, me bucko, and you must have a tank o' N20 and O2 on t' field. Avast! Blimey! Aerotech.s system had t' advantage o' allowin' you t' fill t' tank before comin' t' t' launch, arrr, but had t' disadvantage o' havin' a complex pyrotechnic valve system that is expensive, complex t' set up, and requires a haz mat fee for shipping.

Recently, hybrid technology has come down t' t' Level 1 arena. Avast! Ratts Work.s was t' first company that offered a certified hybrid system that any level 1 user can use. T' ground support is pricey, but t' design o' t' motor is a lot simpler than what Aerotech and Hypertek have t' offer. Ya scallywag! T' reload kits do nay require a hazmat fee, arrr, matey, but they do nay come with igniters or pre-heater charges. Begad! However, shiver me timbers, some dealers (ie Pratt Hobbies) throw these components into t' kit for you. Begad! T' Ratts Work Hybrid motors are designed t' fit in a 29mm motor tube, arrr, me hearties, with slight modification t' t' rocket for venting. Aye aye! Also, shiver me timbers, t' fuel tank be t' same cylinder as t' oxidizer tank. Avast, me proud beauty! T' fuel and oxidizer are separated by a .floatin' bulkhead.. Begad! T' fuel is consumed from t' top t' t' bottom. This means that t' pressure o' t' N2O pushes t' bulkhead down as t' fuel is consumed. They have three motor designations, H70, arrr, matey, I80, and I90. Begad! T' H70 and I80 use t' same size grain, ya bilge rat, but t' case is longer.

Construction:

I won a H70 case and a few loads on a ROL auction. Robert Galjes already had t' ground support system for t' RATT's work system and offered CMASS members access t' it, ya bilge rat, arrr, so t' only thin' that I required for it be a rocket t' fly it in. Aye aye! Blimey! T' H70 has a 3 second burn time, matey, and only has a total impulse o' about 180 n/s. Ahoy! Blimey! I wanted a rocket that be light enough t' launch with t' motor, and t' added weight o' t' recovery hardware, and stay within 2000 ft so I can don.t risk loosin' t' rocket in t' tree filled New England area. Avast! Blimey! I decided that t' Aerotech Mirage be t' perfect candidate. It can launch on a motor as small as a F25, ya bilge rat, and with me calculations, me bucko, shiver me timbers, will go about 1,500 ft with a 180 n/s motor. My fifteen year old friend Ryan Sebastian wanted t' help out with t' project, so he became me partner in designing, and buildin' t' rocket.

There were a couple conditions that I wanted for this rocket. Avast! Avast! It had t' carry electronics t' deploy t' recovery system. I wanted t' put a bulkhead near t' engine that will hold t' charge, ya bilge rat, yet protect it from any leakin' N2O. But I also want t' option o' launchin' t' model with conventional motors. Ya scallywag! So t' charge bulkhead had t' be removable. Avast, me proud beauty! Because o' this, me hearties, t' three sections o' t' Mirage have t' be removable. Avast, me proud beauty! I decided t' use screws t' hold t' rocket together.

T' Hybrid Mirage be built with three main sections. Begad! T' Booster Section, Parachute Bay, and Payload section. Begad! T' Motor Section be t' lower section o' t' Aerotech Mirage, and is heavily modified. Avast! Begad! T' motor hook is still used, but t' motor hook is trimmed t' allow t' longer H70 motor t' pass beyond t' motor hook. Avast, me proud beauty! It is attached in t' position that t' hook locks over t' aft closure o' t' Hybrid, shiver me timbers, and standard 29mm High Power motor. Ya scallywag! Also, this section has t' ventin' tube permeably attached t' t' airframe.

T' parachute bay, obviously, is where t' recovery system o' t' rocket is kept. Arrr! It is also t' section that t' ejection bulkhead is attached to. Begad! Avast, matey, me proud beauty! A paper rin' is attached inside t' tube so t' forward face o' t' bulkhead rests against it. Begad! When t' booster section is attached, t' tube coupler presses t' bulkhead against t' ring. Arrr! This creates a nice seal betwixt t' motor bay and t' parachute bay. Ya scallywag! When t' Mirage is flown with a regular motor, t' bulkhead is simply omitted.

T' Payload Section o' t' rocket is mostly empty space. Blimey! T' electronics for t' recovery system is located in t' tube coupler. Begad! Aye aye! I decided that I would use me custom built timer for recovery. Well, blow me down! Ahoy! I designed t' timer t' use a .burn wire. t' start t' timer. Begad! T' utilizes this, matey, I had a couple short bolts stickin' out o' t' side o' t' rocket. Aye aye! Each bolt is a terminal which a .jumper. Avast, me proud beauty! wire is connected too. Well, blow me down! T' jumperwire is fastened t' t' launch rod. Avast! When t' Mirage takes off, me bucko, arrr, t' jumper pulls free from t' bolt, thus startin' t' timer.

Flight:

T' first opportunity t' try out t' Hybrid Mirage came on July 27th, 2002. Arrr! Begad! Blimey! It did nay work very well though. Avast! Blimey! There was a N2O leak in t' vent tube. Avast! Blimey! T' N2O filled t' motor section, and spread into t' parachute compartment. Blimey! Blimey! Just before t' countdown for ignition be started, t' N2O in t' parachute compartment pushed t' payload section off t' rocket, matey, arrr, which started t' timer. T' countdown be aborted, me hearties, and t' N2O dump button be pushed. Arrr! Blimey! While t' oxidizer be bein' drained, t' charge went off. Avast! Paper, Wood, Oxidizer.... now a heat source? You guest it. Well, blow me down! Blimey! Fire. Blimey! Well, me bucko, blow me down! Blimey! For about five seconds, t' insides o' t' parachute compartment was engulfed in flame. Blimey! Blimey! Blimey! I did nay know this until I dismantled t' rocket, hopin' t' reload it. Ahoy! Blimey! T' charge bulkhead was completely chard. It disintegrated just by handlin' it. Begad! Aye aye! Blimey! About a quarter o' t' inside wall o' t' body tube was burned away from t' heat.

When t' Sept 14th rocket launch came, Ryan and I decided t' launch t' Hybrid Mirage again. Aye aye! Robert Galjes could nay make it t' t' launch with t' ground support equipment and t' tank o' N2O, matey, so Ryan and I decided t' launch it with a conventional motor, a G75-10J. Avast, me proud beauty! I decided t' arm t' timer too& just t' make sure it works. Begad! Avast, me proud beauty! T' lift off o' t' Hybrid Mirage was beautiful. T' black and silver rocket streakin' skyward, leavin' behind a dark smoke trail& nice :-). Well, blow me down! Avast! T' timer deployed both chutes right at apogee, and t' rocket recovered without a scratch.

At NSL 2003, shiver me timbers, Ryan and I launched our Hybrid Mirage with t' motor we built it for. Arrr! T' prevent t' same problem we had last time, ya bilge rat, ya bilge rat, I secured t' vent hose t' t' motor with hot melt glue. Avast, shiver me timbers, me proud beauty! Blue Thunder propellant cut off a F39, and a Magnelite igniter be used t' start t' motor. Begad! Well, blow me down! T' H70 motor ignited instantly, and lofted t' Mirage off t' pad with ease. Beautiful motor; small bright flame, very little smoke. Well, blow me down! I don.t think it burned for t' full three seconds, matey, maybe t' N2O tank be t' warm, so t' motor did nay get a full fill o' oxidizer. Begad! T' timer deployed both chutes a couple seconds after apogee, endin' its perfect flight.

Summary:

Overall, arrr, t' Hybrid Mirage project was a success. We built a rocket that could fly on a Hybrid motor, and convention motor. Avast, me proud beauty! Blimey! Future plans include more H70 launches with a PICO altimeter, ya bilge rat, and don't be surprised if you see a I80 case in me hands in t' near future ;-).