Offset or off-axis nose weight?

[lakeroadster]

But nothing can beat flying your clustered oddroc. "I once flew a three tractor motored Mercury Redstone Capsule...gonna fly a cluster, four Staged Saturn V, yeah that's the ticket!" Thats neither fib nor fantasy!

Aaaah, you like flying unevenly weighted oddrocs do you? NUDGE NUDGE SAY NO MORE!

You should know better than to try to root around in the brain bucket of an odd-roc scum.

 

[Daddyisabar]

You should know better than to try to root around in the brain bucket of an odd-roc scum.

All you will find is a matrix of dark side mindsims!

Asymmetric weighting and thrust vectoring to bring balance to your extremely poor rocket designs. We must be cautious.

 

[lakeroadster]

All you will find is a matrix of dark side mindsims!

Asymmetric weighting and thrust vectoring to bring balance to your extremely poor rocket designs. We must be cautious.

pssst. hey buddy... want to buy some Aluminum Adjustable Rocket Fin Elevators......

 

[KenECoyote]

Very interesting experiments / hypotheses.

Main motor is not canted but is off-center / shifted upwards since the tail is an oblique cone. I thought this would partially offset the tendency of plane-style rockets to arch up due to the tail (I did not really think about the canopy drag effect but have seen something like that in other rockets). In my experience (not a huge sample size due to so many changes in versions), the F-104 rocket arched over the top more with a C5-3 than with a D12-3 but this is without controls for wind or other variables.

F-104 on C5-3

F-104 on D12-3

F-104 w/ D12-5 + 2nd canted A-10 motor (I think it got a little hung up on the rail due to canted A-10 igniting faster than D12)

There's a lot of variables at play here, so it's not so simple...

1. Weathercocking does appear to affect the first C5 flight. Also winged rockets have that tendency and it's more apparent when it's lighter.
2. The D12 flight was straight with slight wind the other direction. When the rocket is heavier off a higher thrust motor, it tends to weathercock less imo

At my next club launch (hopefully there will be less or no wind) I plan to try a control flight and a test flight one after the other.

 

[KenECoyote]

All you will find is a matrix of dark side mindsims!

Asymmetric weighting and thrust vectoring to bring balance to your extremely poor rocket designs. We must be cautious.

pssst. hey buddy... want to buy some Aluminum Adjustable Rocket Fin Elevators......

 

[Daddyisabar]

pssst. hey buddy... want to buy some Aluminum Adjustable Rocket Fin Elevators......

I waive my hand and say "It is time to go home and re-think your rocket designs. Offset nose weight is not required in safe, 3-4FNC designs." Thus, the Jedi mind trick is complete.

Obi-Wan Kenobi always finds nothing but trouble in oddroc cantinas. It is the way of the Force. Like George Lucas repeating poetry.

 

[Daddyisabar]

There's a lot of variables at play here, so it's not so simple...

1. Weathercocking does appear to affect the first C5 flight. Also winged rockets have that tendency and it's more apparent when it's lighter.
2. The D12 flight was straight with slight wind the other direction. When the rocket is heavier off a higher thrust motor, it tends to weathercock less imo

At my next club launch (hopefully there will be less or no wind) I plan to try a control flight and a test flight one after the other.

If there is a little wind I always set the wing edge into it. Then run away and try to get the airplane rocket launched as quickly as possible. Keep it out of the horrid, weather cocking wind for as long as possible. Thrust getting all that nose weight going up, building up all that lovely inertia is your friend. Keeping those airplane wings, I mean fins, out of an attack angle to the wind is good. Do let it fly like the airplane it so desperately wants to be. Force it, by will alone if necessary, to fly like a model rocket should!

 

[Daddyisabar]

Long story short. If you are trying to balance your unbalanced rocket with unbalanced nose weight then two wrongs don't make a right. Be safe and sound. Learn the ways of the Jedi and do not be tempted by the dark side. Pack that weight in evenly. Thus endeth the lesson.

 

[burkefj]

I would say in your case it's more likely just due to the high T-tail extra drag and potentially not being perfectly in line with the thrust line than the cockpit or mass off centerline.

 

[jqavins]

Like others, my mind sim says that off center nose weight should make very, very little difference. If you want to add a pitching moment, I suggest that a slight, and I mean SLIGHT adjustment to the fins wil be more effective. To induce a bit of negative pitch, delicately sand a little bit off of the bottom side of the leading edge, or the top side of the trailing edge, of the T-tail.