Mathmatical Modeling for Missiles

[almullao]

Hello,

 

I'll go straight forward to the subject, I actually like missiles drag modeling (maybe guidance can evolve slowly), but I feel that the coanda effect isn't being taken into consideration, also I'm not sure if the missiles structure flexibility and drag coefficient change while turning is that accurate.

 

I've done some testing, according to my calculations the Aim 54 was able to pull over 40gs to intercept a maneuver, also the Aim 120 for example was losing so much energy while turning, those numbers are affected by the coanda effect and structure flexibility that will actually reduce the drag area thus maintaining more energy.

 

Well, I'm a mechanical engineer, I believe I may be able to produce (no promises) mathmatical mideling for the missiles structure flexibility, coanda effect and drag formulas based on the previous variables.

 

If my work will be taken seriously, I can begin and hopefully may be able to contribute.

 

What do you think?

Edited September 6, 2019 by almullao

[Mars Exulte]

I think a random forum post isn't the way to be ''taken seriously''. If you want to be ''taken seriously'' you should contact ED directly. Also, I'm sure they HAVE all manner of engineers.

[almullao]

I think a random forum post isn't the way to be ''taken seriously''. If you want to be ''taken seriously'' you should contact ED directly. Also, I'm sure they HAVE all manner of engineers.

 

I believe you're right, I'll toss them an email with some ideas and basic calculations.

 

For sure they have engineers, but what I noticed was obvious. For example if the Phoenix or the R33 or 37 turn so hard with such a solid structure, the coanda effect and drag won't be able to hold the missile in its path it'll simply sink in the air. Thats why they have g-limiters in the R33 & 37 for example dunno about the Aim 54. Also some designs with longer fins like the R77 and Mica is mainly done to exploit the coanda effect and enhance the missile maneuverability. The Aim 120 design is made thin and flexible to enhance the energy conservation and rang, A sneaky TWS shot with an Aim 120 is deadly.

 

Well, regardless, you're right, I'll write to them and see.

 

Thanks for the reply.

[nighthawk2174]

The 54's G limits are stated as being around 18g for the 54A and in the low 20's for the 54C so even though it may seem they can aerodynamically pull up too 40g there are other factors that play into how hard a missile can turn. Although, it is a known issue (and has been for years) that missiles loose way to much speed in the turn hence why ED dropped lift values by 100-200% across the board to prevent them from killing all of their speed even in light turns. I do wish you luck with this but I doubt ED would ask for your help they have a history of turning down such offers.

Edited September 6, 2019 by nighthawk2174

[almullao]

The 54's G limits are stated as being around 18g for the 54A and in the low 20's for the 54C so even though it may seem they can aerodynamically pull up too 40g there are other factors that play into how hard a missile can turn. Although, it is a known issue (and has been for years) that missiles loose way to much speed in the turn hence why ED dropped lift values by 100-200% across the board to prevent them from killing all of their speed even in light turns. I do wish you luck with this but I doubt ED would ask for your help they have a history of turning down such offers.

 

I understand, but that was just an observation for something that I've done before, structure flexibility and coanda are crucial factors. It's not about the aim 54, I guess it's designed ok with some minor flows, as it's a rigid structure. But the aim 120 is flexible and that's why ppl are complaining about it being draggy especially while turning. Flexible structures are different, imagine that it turns in air like a fish in the water (not exactly but an example).

 

Even if they decline, I'll send them my previous university work, they may find it useful and start to account for it slowly.

[nighthawk2174]

I hope for the best then as this stuff needs to get fixed its been nearly 7 years now if i'm not mistaken since the introduction of the "advanced" missile model and we still have major issues.