The exciting Heavenly Hobbies’ BACKDRAFT (tm) is a dual-engine rocket that uses the best practices of the past with new, cutting-edge thinking to create a model rocket that is nothing short of fantastic!
The BACKDRAFT(tm) is based on a BT-60 airframe, for an ideal combination of solidity, stability and efficient use of engine power. This design offers straight-through ejection gas ducting and EZject(tm) piston-actuated system for rear ejection. With the EZject(tm) system, flameproof wadding and / or parachute protectors are completely unnecessary, making field preparation a snap! The rear ejection of the recovery system renders the body tube “zipper” problem a thing of the past!
The BACKDRAFT(tm) looks like a 2-stage vehicle, with booster and sustainer sections. The propulsion module (booster) holds the primary 24mm engine. The sustainer holds a secondary 24mm engine. But the BACKDRAFT (tm) is not a 2-stage rocket. In this model, the secondary engine has exchanged places with the recovery system. The secondary engine has been moved forward, behind the nosecone, while the parachute has moved back. This secondary engine has also been rotated 180°, so that the nozzle points to the sky while the rocket sits at the launch pad. This arrangement sets the stage for the TailWind (tm) delayed deployment system.
The basic idea for Heavenly Hobbies' exclusive TailWind (tm) delayed deployment system is to reduce drift by skipping ejection at apogee and, after a suitable delay, use a "retro-firing" engine to slow down the rocket for deployment of its recovery system.
Common Dual Deployment (tm) techniques for drift reduction use electronic devices to force the ejection of a streamer or small “drogue” parachute to cause a fast, but controlled, descent. A larger parachute is subsequently deployed by similar means. The idea is to reduce the time the rocket is subject to crosswind drag, therefore reducing the drift. However, a rocket using the Tailwind (tm) system does not “break up” to deploy a recovery device in its coasting phase after apogee. It, therefore, presents a smaller frontal area to crosswinds. Less frontal area means less drag and less drift. Also, crosswinds acting on parachutes create lift forces, so not having a parachute in this phase of the descent also helps. Moreover, a compact rocket presents a much more aerodynamic profile in the vertical direction, allowing higher (more negative) terminal velocity limits. This leads to shorter periods during which the model rocket is subject to crosswinds, and again, less drift. In simple words, the Tailwind (tm) system is superior to the common Dual Deployment (tm) technique in reducing crosswind drift.
In order to harness the drift reduction power of TailWind (tm), an advanced control system is needed. Heavenly Hobbies’ H.H Simit(tm) (v1) is a custom-designed, computer-based control application for the BACKDRAFT(tm) model rocket. H.H. Simit(tm) (v1) is included in all new BACKDRAFT(tm) kits. It provides simulated altitude, velocity and acceleration information for the model’s flight, using an integrative approach that samples flight conditions 10 times per second. It also allows the hobbyist to easily choose primary and secondary engines (and their respective delays) using the provided data.
Future rocket or engine modifications will not be a problem as the information database is user-editable. You don’t need to buy a new version of H.H. Simit(tm) to fly a new version of BACKDRAFT or to accommodate the thrust characteristics of a new engine! This flexibility is integral part of the software’s design. Having the power of H.H Simit at your fingertips renders the use of expensive onboard electronics unnecessary!
A 3/16" diameter launch rod and a 12-volt launch system are required. A 1/4" diameter rod is recommended together with the BACKDRAFT(tm) Accessory Kit. These items are sold separately.
Skill level: 4
· TailWind (tm) drift reduction system (A Heavenly Hobbies’ exclusive!)
· EZject (tm) piston ejection system (A Heavenly Hobbies’ exclusive!)
· Laser-cut plywood fins and centering rings
· Slotted airframe for TTW fin mount
· Nylon parachute
· Kevlar (R) shock cord
· First 100 kits signed and numbered
· Length: 36.625 in.
· Diameter: 1.679 in.
· Weight: 7.5 oz.
Primary / Secondary:................ Altitude:
. D12-0 / C11-3 ..................... 335 ft.
. E9-4 / D12-0 ...................... 1075 ft.
. E15-4 / D12-3 ..................... 1540 ft.
MINIMUM SYSTEM REQUIREMENTS:
. Pentium III processor, running at 533Mhz
. 256 Mb RAM
. 1 Gb Hard Disk Space
. 800 x 600 resolution display, showing 16 bit color
. Microsoft Windows XP
. Microsoft Excel 2000
. Microsoft Word 2000
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