pr_rocket04
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Well, after talk about this project amoungst others for quite some time, I finally got my fiberglass fins (thanks Doc) and have begun the build.
While I could have put this in the scratch-built section, I chose to put it here to get advice from you all, as the goal of this design is maximum altitude.
To start, I slotted the booster for fins, used a motor case w/ wax paper as a mandrel, and mounted the fins with fairly heavy fillets (with of coarse my fav...West System and a bunch of 404 filler). Cured them in the oven yesterday, and I guess you could consider them semi-through-the-wall, as they sit on the motor case.
Now, as it stands, 29mm phenolic I know is strong enough to endure mach 1 stress (long burn motors) created by the axial flexxing between the two sections...there shouldn't be that much force in the flight which it will first endure (longburn-I staging to an H). But, the whole idea is to have this rocket also endure axial loading under boost from a K670GG minimum diameter booster when it flies successfully, and becomes a three stager.
With the addition of a second 54mm booster, this will be one long skinny rocket. With that being said, the transitions will use outhung motor casings, and the two upper stages become a boosted dart when the K670 burns out (EDIT: didn't mean boosted dart, but they will quickly drag separate).
Knowing that axial/torque (I forget which is the correct term for the leverage affect of a long airframe) loading will take place near the 29mm booster fins- just above the 54-29mm transition, I'm concerned that the high initial thrust will want to snap the airframe just above the fins.
Has anyone experienced similar designs in which this sort of loading on a very long airframe was endured? I'm trying to come up with a relative estimate on just how much reinforcement the 2nd booster or possibly even sustainer need, without overdoing it on the carbon layup, and possibly making it weigh as much as a 38mm, because I have to keep in mind...this is designed more for the 2 stage flight configuration, just needs the added capability for another booster.
Thanks guys.
While I could have put this in the scratch-built section, I chose to put it here to get advice from you all, as the goal of this design is maximum altitude.
To start, I slotted the booster for fins, used a motor case w/ wax paper as a mandrel, and mounted the fins with fairly heavy fillets (with of coarse my fav...West System and a bunch of 404 filler). Cured them in the oven yesterday, and I guess you could consider them semi-through-the-wall, as they sit on the motor case.
Now, as it stands, 29mm phenolic I know is strong enough to endure mach 1 stress (long burn motors) created by the axial flexxing between the two sections...there shouldn't be that much force in the flight which it will first endure (longburn-I staging to an H). But, the whole idea is to have this rocket also endure axial loading under boost from a K670GG minimum diameter booster when it flies successfully, and becomes a three stager.
With the addition of a second 54mm booster, this will be one long skinny rocket. With that being said, the transitions will use outhung motor casings, and the two upper stages become a boosted dart when the K670 burns out (EDIT: didn't mean boosted dart, but they will quickly drag separate).
Knowing that axial/torque (I forget which is the correct term for the leverage affect of a long airframe) loading will take place near the 29mm booster fins- just above the 54-29mm transition, I'm concerned that the high initial thrust will want to snap the airframe just above the fins.
Has anyone experienced similar designs in which this sort of loading on a very long airframe was endured? I'm trying to come up with a relative estimate on just how much reinforcement the 2nd booster or possibly even sustainer need, without overdoing it on the carbon layup, and possibly making it weigh as much as a 38mm, because I have to keep in mind...this is designed more for the 2 stage flight configuration, just needs the added capability for another booster.
Thanks guys.