You've "nailed" it!
NICE!!!
Did you know you could kinda sim the shape of the nose's hammer in OR? (at least cosmetically) Fin width is the "span" of the fin, shape is half of the cross section. The fin is attached to a PBT of 0 length and diameter, offset by the length of the fin root.
What K'Tesh is proposing there is for visuals only. It will not simulate correctly.My main reason for using OR is for simulation of the rocket flight.
Any idea if the modification you outlined creates a more or less accurate flight simulation?
NICE!!!
Did you know you could kinda sim the shape of the nose's hammer in OR? (at least cosmetically) Fin width is the "span" of the fin, shape is half of the cross section. The fin is attached to a PBT of 0 length and diameter, offset by the length of the fin root.
View attachment 418141
Any idea if the modification you outlined creates a more or less accurate flight simulation?
Is that airfoil shape a result of the new developer version?
No, like Neil said, it's cosmetic only.
No, it's a result of me trying to figure out how to make a wing shape and playing with body tube diameters. You can do it with 15.03.
View attachment 418402
https://www.rocketryforum.com/threads/offset-wings-fins-in-openrocket.138593/#post-1662595
And now... Back to your regularly scheduled program.
If you look at the .ork file I created, you'll notice that it's not an airfoil, but a teardrop shape.An airfoil... on "The Hammerhead" would likely result in the rocket looping into a spectacular lawn dart.
Now.. where to place the ring...
I theeeeeeenk a teardrop technically IS an airfoil, just a neutral one. Although for that matter, straight edge rectangles are ALSO airfoils, just neutral and draggy and inefficient ones.If you look at the .ork file I created, you'll notice that it's not an airfoil, but a teardrop shape.
I theeeeeeenk a teardrop technically IS an airfoil, just a neutral one. Although for that matter, straight edge rectangles are ALSO airfoils, just neutral and draggy and inefficient ones.
airfoil: A streamlined surface designed in such a way that air flowing around it produces useful motion.
It's not the phantom tubes that are the problem here. It's that the whole hammer is an ultra-wide fin (or pair of fins). OR simply is not designed to sim fins like that.Thus my question to Tesh about how he produced the front. If 0-thick tuebs are involved its a no from me. I make sims for data, not drawings
Thus my question to Tesh about how he produced the front. If 0-thick tuebs are involved its a no from me. I make sims for data, not drawings
It's not the phantom tubes that are the problem here. It's that the whole hammer is an ultra-wide fin (or pair of fins). OR simply is not designed to sim fins like that.
One could make two versions, one with the hammerhead as you have it, flat and thick, and the other no hammerhead and a mass object instead. Then you know how much drag OR believes it's adding. Not how accurate that is, of course, but you'd know it's adding something.Would you agree that, if for no other benefit, having the hammerhead in the simulation adds weight in the correct location? Sure, a mass component could just be used but one would speculate that OR would also add drag based on the fin set configuration... but how would one know for sure?
One could make two versions, one with the hammerhead as you have it, flat and thick, and the other no hammerhead and a mass object instead. Then you know how much drag OR believes it's adding. Not how accurate that is, of course, but you'd know it's adding something.
I may use a regular nose cone to prove the flight worthiness of the rocket. Then after a successful launch, install the Hammerhead to see how it affects the flight.
It's definitely worth putting in the simulation because it has an enormous affect on both mass, CG, and CP. As always the sim may not be perfect but it'll give an idea.It's simulated as a trapezoidal fin set, with fin tabs that go to the vessel C/L, made from spruce.
Would you agree that, if for no other benefit, having the hammerhead in the simulation adds weight in the correct location? Sure, a mass component could just be used but one would speculate that OR would also add drag based on the fin set configuration... but how would one know for sure?
You get a "thick fin warning", which I *think* refers to the miscalculation of the fin/body effects when the fin is too thick relative to the body. I don't know for sure but I wouldn't trust it to simulate correctly on a fin 2 inches wide and 1/4" tall, for a whole host of reasons.Neil, are you saying that if one takes a 3FNC design but makes the fins an inch thick the simulation results would be compromised? And if so, in what way?
I may use a regular nose cone to prove the flight worthiness of the rocket. Then after a successful launch, install the Hammerhead to see how it affects the flight.
Ugh. This late in the game the immediate thought is to add nose weight. But with the CG already so high it would take a lot of nose weight to move it enough more. The basic problem is much more high CP than low CG, so it really needed bigger fins.When I make this change, CP ends up right on top of CG, at least with the included F motors:
View attachment 418454
Ugh. This late in the game the immediate thought is to add nose weight. But with the CG already so high it would take a lot of nose weight to move it enough more. The basic problem is much more high CP than low CG, so it really needed bigger fins.
What kind of F motor is in it? If it's Estes's 29 mm BP F, then you might benefit by going composite. The Estes motors weigh about 100 grams. AeroTech 24 mm F motors weigh about from 50 to 70 grams. With the motor being further from the present CG than the nose, each gram removed from the tail will have a bigger effect than each gram added to the nose.
This was always my concern with the hammerhead.
Ugh.
Looks good, pretty clearly stable, I'd say. I'm curious, did you try without the nose weight?
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