Been working over this concept model for quite some time. It's been on the bench with a few parts built thus far. I think I'm going to up the priority on this work order and get this model built. Thought it would be something others would be interested in. Perhaps others like it have been built, but I've yet to hear of any.
Here's the basics of the concept:
Start with typical 2-stage model. The booster is a linear cluster of 3, though it could easily be bumped to a Y cluster of 4 with a center surrounded by 3. The main airframe has just 1 booster motor behind 1 upper stage. This central booster can be setup for either C6 or D12 based on the expected lift-off weight. Use typical short gap staging between central booster and upper stage.
Either 2 or 3 strap on style booster sections are added around the main airframe. They are going to be powered by B4-2 or B4-4 motors (note the thrust time on should be slightly shorter than the thrust time of the central booster and the central booster must have higher impulse than the strap ons).
These boosters are much longer than the central booster stage as they must extend alongside the upper stage airframe also. Each strap on is basically it's own rocket with motor mount, nose cone, and full recovery system. However they have one large fin on the side away from the main airframe and a very small set of canard style fins at the nose that are perpendicular to the main. These are set with a slight angle (or lifting airfoil) that will be pulling them away from the main airframe slightly. The intent is that when they are released at staging, they will move away with the nose leading the way and begin to tumble outwards. Shortly after staging and tumbling away from the main, they will eject their own recovery systems.
During boost, the strap ons are held in place with a socket on the upper stage that the nose cone is pushing up into. It must hold the nose of the booster so that the outward force can't pull it free. The central booster has pin & socket type connections that securely capture the aft end of the boosters. When assembling for flight, the nose of the boosters is inserted into the upper socket and the central booster is pushed up engaging the aft pins of the boosters. The central booster should also be perfectly indexed to the upper stage to ensure the strap on boosters are parallel and in alignment with the main airframe. Misalignment here could have very undesirable effects during the first second of flight.
The 3 or 4 motors at ground level must be cluster ignited. The strap ons will burn out a bit before the center, but remain attached as they enter coast phase. When the central burns through and ignites the upper, the central booster will stage and release the aft of the boosters as it separates. The upper will now be accelerating under thrust. The strap ons are just coasting and will be left behind to start their tumble for the next second before the motor ejection activates the recovery system.
Will post photos and construction details as I go if there is interest.
Here's the basics of the concept:
Start with typical 2-stage model. The booster is a linear cluster of 3, though it could easily be bumped to a Y cluster of 4 with a center surrounded by 3. The main airframe has just 1 booster motor behind 1 upper stage. This central booster can be setup for either C6 or D12 based on the expected lift-off weight. Use typical short gap staging between central booster and upper stage.
Either 2 or 3 strap on style booster sections are added around the main airframe. They are going to be powered by B4-2 or B4-4 motors (note the thrust time on should be slightly shorter than the thrust time of the central booster and the central booster must have higher impulse than the strap ons).
These boosters are much longer than the central booster stage as they must extend alongside the upper stage airframe also. Each strap on is basically it's own rocket with motor mount, nose cone, and full recovery system. However they have one large fin on the side away from the main airframe and a very small set of canard style fins at the nose that are perpendicular to the main. These are set with a slight angle (or lifting airfoil) that will be pulling them away from the main airframe slightly. The intent is that when they are released at staging, they will move away with the nose leading the way and begin to tumble outwards. Shortly after staging and tumbling away from the main, they will eject their own recovery systems.
During boost, the strap ons are held in place with a socket on the upper stage that the nose cone is pushing up into. It must hold the nose of the booster so that the outward force can't pull it free. The central booster has pin & socket type connections that securely capture the aft end of the boosters. When assembling for flight, the nose of the boosters is inserted into the upper socket and the central booster is pushed up engaging the aft pins of the boosters. The central booster should also be perfectly indexed to the upper stage to ensure the strap on boosters are parallel and in alignment with the main airframe. Misalignment here could have very undesirable effects during the first second of flight.
The 3 or 4 motors at ground level must be cluster ignited. The strap ons will burn out a bit before the center, but remain attached as they enter coast phase. When the central burns through and ignites the upper, the central booster will stage and release the aft of the boosters as it separates. The upper will now be accelerating under thrust. The strap ons are just coasting and will be left behind to start their tumble for the next second before the motor ejection activates the recovery system.
Will post photos and construction details as I go if there is interest.
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. I got to build me another one!!
