Loc phoenix nose weight

[Rocketcamper123]

For a LOC phoenix missile either 4, 5.5, or 7.5 diameter how heavy of nose weight are we talking? I know its relevant to the size of motor. So for a 7.5 diameter and your flying a M how much nose weight potentially would you need for a stable 2 calibers?

 

[schneijt]

For a LOC phoenix missile either 4, 5.5, or 7.5 diameter how heavy of nose weight are we talking? I know its relevant to the size of motor. So for a 7.5 diameter and your flying a M how much nose weight potentially would you need for a stable 2 calibers?

There is no answer to this question other than “enough to make it stable.” You need to use RockSim or Open Rocket to look at an existing file for the kit you choose to build, or create your own build file; that will help you get a rough estimate of how much weight you’d need. Ultimately, you need to know where the center of pressure is for any build, and add nose weight if needed to get the center of gravity far enough forward for stable flight. In general, I calculate the weight of the largest motor I could/will possibly fly in any kit that I build, and I make sure the nose weight (if needed) is enough for there to be enough stability for the biggest motor it could ever fly on.

 

[Rocketcamper123]

Thank you sir. I have liked the phoenix since my childhood. I was thinking of doing a 7.5 inch but to fly a m1297 or bigger if I have to add

There is no answer to this question other than “enough to make it stable.” You need to use RockSim or Open Rocket to look at an existing file for the kit you choose to build, or create your own build file; that will help you get a rough estimate of how much weight you’d need. Ultimately, you need to know where the center of pressure is for any build, and add nose weight if needed to get the center of gravity far enough forward for stable flight. In general, I calculate the weight of the largest motor I could/will possibly fly in any kit that I build, and I make sure the nose weight (if needed) is enough for there to be enough stability for the biggest motor it could ever fly on.

multiple pounds in the nose I may not even bother and choose another scale kit.

 

[heada]

I have the 5.5 inch kit and fly it on 75mm K/L motors with no noseweight. It all depends on your build and motor choice.

 

[Rocketcamper123]

I have the 5.5 inch kit and fly it on 75mm K/L motors with no noseweight. It all depends on your build and motor choice.

Cool good to know. The 5.5 maybe easier to handle and transport.

 

[heada]

I got my kit from the previous owner of LOC when the kit was a prototype. It might be slightly longer than the current kit and I added an electronics bay for dual deployment. Flys great on K550 size motors.

 

[Glasspack]

I got my kit from the previous owner of LOC when the kit was a prototype. It might be slightly longer than the current kit and I added an electronics bay for dual deployment. Flys great on K550 size motors.

Aaron, Is that old kit you got from LOC ....Thick Card Tube or Fiberglass ?

 

[heada]

It's the standard LOC cardboard. I don't think LOC has any fiberglass kits, do they?

 

[heada]

Out of curiosity I checked the LOC site for specs on the 5.5in kit and it says it's 56in tall. My kit is 84in tall so obviously they changed it to be more scale and thus need nose weight. You could extend the 7.5in kit similar to mine to remove the need for nose weight.

 

[KenC]

I built a scratch 4" Blue Tube true to scale model of the AIM 54C with a 38mm motor mount. Motor ejection only, no dual deploy My nose cone is 706g with the additional weight in the tip.

I completely filled the fin can up through the top fin set with 2lb urethane foam. This gives me 1.48 calibers stability using a 38-1080 motor J570W or J825R to about 4000'. It also flys well with 1.62 calibers on a I180 to about 1300' (photo below) and is easier to see the entire flights and less of a walk to recover. It whistles nicely...

The stability is calculated using the Rocksim modified Barrowman equations, so Open Rocket calls for more nose weight. I also don't fly it unless there are light winds.

 

[user 30299]

I have a Madcow 4" Phoenix that uses 556 grams of nose weight. I use a bulkhead setup in the nose to hold a lead puck. The rocket is only 41" long and can take 38mm motors.

 

[Cameron Anderson]

Two calibers of a stability on an airframe that's what, maybe 12 calibers long?
The "one caliber of stability" rule of thumb goes out the window for shorter rockets and taller rockets. In my experience, anything shorter than 15 calibers needs less than 1 caliber for stable flight. I have a nosecone rocket that is 4" across and 17" tall and it flies fine with about 0.5 calibers of stability. That's am exteeme example but you get my point.
If you add weight to get 2 calibers, all you're going to be doing is hauling a lot of dead weight to apogee - one should be more than adequate.

 

[Rocketcamper123]

Two calibers of a stability on an airframe that's what, maybe 12 calibers long?
The "one caliber of stability" rule of thumb goes out the window for shorter rockets and taller rockets. In my experience, anything shorter than 15 calibers needs less than 1 caliber for stable flight. I have a nosecone rocket that is 4" across and 17" tall and it flies fine with about 0.5 calibers of stability. That's am exteeme example but you get my point.
If you add weight to get 2 calibers, all you're going to be doing is hauling a lot of dead weight to apogee - one should be more than adequate.

Yes you make a great point sir. I guess most of my flights are over mach. So most of my flights are high performance. Those rockets are min diameter sport rockets not scale models. I have a loc warlock and it has .5 calibers on a AT J570

 

[Ez2cDave]

For a LOC phoenix missile either 4, 5.5, or 7.5 diameter how heavy of nose weight are we talking? I know its relevant to the size of motor. So for a 7.5 diameter and your flying a M how much nose weight potentially would you need for a stable 2 calibers?

REALLY ? If you took Rocketry seriously, you would already know how to statically-balance a rocket, long before you ever flew an HPR motor, and that the value varies from size to size and rocket to rocket . . . C'mon, man !

Dave F.

 

[Ez2cDave]

Yes you make a great point sir. I guess most of my flights are over mach. So most of my flights are high performance. Those rockets are min diameter sport rockets not scale models. I have a loc warlock and it has .5 calibers on a AT J570

You might also want to remember that the CP tends to "wander" as airspeed increases, especially over Mach 1.

Dave F.