Superscale AIM-9 Sidewinder

[miniflyer]

Dear community,

i joined this Forum mainly because it contained so much wonderful drawings, details and pictures that can be used to draw and construct a scale missile. At this point kudos and many many thanks at all the contributors! Thanks!
While i did "build" and launch a few of the estes rockets back in my youth, i never really followed the rocketry anymore and grew more and more fond of radio controlled scale jets. While building some ordonance in various sizes, and also for a 1/6 scale F-16 Falcon, the idea grew that the two worlds had much similarity, and maybe my design could be used to make a superscale flying rocket model. I did make a variant that includes an electric smoker unit, so why not also put in a rocket motor and a parachute?
What do you think? What would be a desireable size? What motors can be used and what weiht would be the target to get it flying decently?

Here are some pictures of the work i have done, and also a short video of the unit smoking...

Cheers Hank






View attachment Smokewinder.mp4

 

[6inchmonster]

That looks phenomenal.

 

[miniflyer]

Thank you.
I have also made a stand to put up on my desk when not in use....



What size and weight would be a good scale for rocketry, and what motor might be a good idea?

 

[neil_w]

You may or may not find this answer to be helpful, but here goes:

What size and weight would be a good scale for rocketry, and what motor might be a good idea?

Size, weight, and motor are all interrelated. You would conceivably pick any one of the three to start, and then work out the others. Most commonly one would start with the size, and then figure out approximately what it's going to weigh, and then choose an appropriate motor. Or if there's a motor you want to use, you can start there and then figure out what the rocket needs to weigh, and then figure out the size. Etc.

Any size can work, from a 9"-long Micromaxx model up to 1:1 or even beyond. Your choice. The one shown in your hand is a perfectly reasonable flying size, which should come in the 2-3 oz range (or maybe up to 4 oz if there's a lot of plastic detail), and would fly on 18mm or 24mm motors. But you could go bigger or smaller as desired.

Do you have any rocketry experience? If not, then starting off with a low-powered model would be wise, perhaps BT55 (1.325") or BT60 (1.633"). Scale accordingly.

 

[Aslansmonkey]

Another thing I find helpful when designing rockets is looking at the stats of the motors I'm interested in using. I've attached an Estes Engine Chart to this message as an example. When I'm building for a D or E sized (24mm) motor, I note that the minimum lifting weight of a D12-5 is 283g, but you need to subtract the 43g of the motor itself from that value, so my empty rocket shouldn't weigh more than 280g. This is a rough guideline, mind you. If you have a longer launch rod it can weigh a little more, for example. From that I size and scale the rocket appropriately.

I'll point out that I've had several successful models that are slightly overweight for the motors I've used. I've also had unsuccessful models that are underweight. In the latter case this was due to stability issues. In short, there's more to it than just lifting capacity. But something like this chart should give you a good starting point.

 

[K'Tesh]

Very COOL!!! However, I suspect that an air launch of this from an RC plane would violate rules of Tripoli and NAR. The only "Target" we should aim for is the open sky. Presuming that you are only intending on launching it vertically (or within 30 degrees of it), from what I've read, the canards need to be capable of freely moving with at least 2/3rds of the surface area behind the pivot. Otherwise, any misalignment could send it off in an unintended direction.

FWIW: I used to load the real things. Well, more often than not, the training versions that were usually carried by our F-111Es at UH... I still, to this day, want to build a 1/1 scale version of this (with working rollerons).

I'd be willing to sim one up... But I'd need a sample (sent to me in China (I'm an English teacher now)) to ensure accuracy. Here's an example of some of my work... (It's old, and I've gotten better since then)

 

[neil_w]

Very COOL!!! However, I suspect that an air launch of this from an RC plane would violate rules of Tripoli and NAR.

Oh wait, is that what the OP wants to do? If so, then nope. Do not.

 

[K'Tesh]

Oh wait, is that what the OP wants to do? If so, then nope. Do not.

Re-read the OP... I saw the word "target" and fixated on it... (Target Fixation is a thing with me)... Looks like he meant to say "target weight". So I was wrong.

 

[miniflyer]

OK, theres no intention of launching from an Airplane.
MY personal use will be the smoke-carrying capability in a scale "accessory"......
Buuuut since the file is freely scalable to any size, i thought it might be nice to have a version to sit on an office desk to look nice, or even a launchable and parachute-recoverable version in a "decent" size......

While i do have some very basic rocketry skills, they were gathered in the teenage age relying solemly on Estes kits. I have never designed my own, so the entire power requirement and such is totally new to me. The descriptions have helped a lot so far.

BTW, the front wings are fixed. They are glued in into an alignment pin which aligns them to 0.03mm accuracy (!), so misalignment is not an issue.
The rollerons were drawn off the factory drawings. On this it will be fixed also, but starting around 1/4 scale they could even be made operational. Theres a nice video showing the function of the rollerons on youtube.....

 

[neil_w]

What are your models (which BTW are beautiful) made of? What are dimensions and weight of one of them? Let's start here, to get a baseline idea of what we're dealing with.

I foresee two challenges:
1) Depending on the materials you used, they may or may not be fairly heavy, although this can generally be compensated with more thrust
2) Stability: again, depending on the materials, I can see a possibility that you've got some significant weight in the tail, bringing center of gravity back, *and* the canards are going to bring the center of pressure forward somewhat. If you have a stability issue that can be solved with nose weight, although then you might need a larger, heavier motor, etc.

 

[K'Tesh]

Please realize, that I'm not trying to shoot your idea down (if you had been thinking of an air launch, yes, I would have, but you've clearly indicated that is not your intention (I offer my apologies for having made the mistake, and as you saw, I quickly caught it, and retracted it). I have a similar desire to build and fly an AIM-9 (only much larger). And while I'm only a L1, and living in China (where I can't launch what I have hear (which is now fairly extensive)), I've done a *LOT* of reading over the 6 years I've been here. The fixed canards are, properly aligned or not, likely going to cause the rocket to be unstable.

The whole reason they're there on the real thing is to steer the rocket quickly towards its target. As such, this missile is designed to be unstable to allow for the flight characteristics it needs, and as it has active guidance that can control it in flight. A hobby rocket, on the other hand likely won't have the hardware to do that (unless you're a very skilled engineer, with experience and materials that you haven't let on about yet).

At a home based launch (not club affiliated) you might be inclined to launch, but I wouldn't want to be responsible if the thing went unstable, or worse, started going unstable (perhaps caused by wind), then achieves a stability and a trajectory that puts ground objects or people in jeopardy. At a club launch, I doubt that a well informed, responsible RSO would allow it especially if there's only even a hint of a breeze.

With the canards allowed to pivot freely they have a much smaller influence on the direction the rocket will take (again, IIRC from my reading, only the area forward of the pivot point will be of influence), and thus the rocket can safely be flown. From what I remember on other AIM-9 builds, the builders used bearings (like the ones found in those fidget spinners) to mount the axles of the canards. In my own mindsim (and I've been mindsimming this for over two decades), I'd use something similar, perhaps with rare earth magnets in the fins and with removable ones in the body tube to "lock" the canards when it's not on the pad, or in the air.

Oh... and I LOVE your renders.... Those are AWESOME!!!

 

[miniflyer]

Thank you both for these extensive inputs.

The material is a high strength, high temperature resistant polymer resin.

I have just taken measurements of 2 of the sizes i have made:

1/10 scale:
Fuselage diameter: 12,7mm (1/2")
Weight: 25g (0.9oz)

1/6.9 scale:
Fuselage diameter: 18.4mm (0.7")
Weight: 70g (2.5oz)

Currently the models are extremely tail heavy, as all tail fins are solid resin. I will be able to hollow them and also reduce tube wall thickness somewhat, so a 1/6 will come in around 80-90g, which will be within the limits for standard motors. A 1/4 scale could fly on a D or E class motor.....

I do have access to a large military training area, so foreign damage can be ruled out for test flights.

Is there a formula or rule of thumb to set a CG?

 

[K'Tesh]

Rule of thumb for CG... Minimum of 1 caliber forward of the CP. Beyond 1.5 calibers forward of the CP, and you're now overstable, and likely to weathercock in wind.

I'd look into a vacuform of the fins, or a hybrid of birch ply, basswood, or balsa, and/or cardstock (Manilla folders come to mind). Much like the fins of the Estes Pro Series Patriot Missile (2066).



Adam Savage recently reviewed an inexpensive vacuform machine on his TESTED channel... Upon further checking it's far too small for the rear fins of the AIM-9, however, it'd be a good size for the rollerons and possibly even the canards.

A 3D print using the ultralight PLA that the boys over at Flight Test might be tempting. However, PLA is a low temp melting plastic, and with the heat from motors, and/or from being in even a parked car in the sun could be disastrous.

 

[neil_w]

Thank you both for these extensive inputs.

The material is a high strength, high temperature resistant polymer resin.

I have just taken measurements of 2 of the sizes i have made:

1/10 scale:
Fuselage diameter: 12,7mm (1/2")
Weight: 25g (0.9oz)

1/6.9 scale:
Fuselage diameter: 18.4mm (0.7")
Weight: 70g (2.5oz)

Currently the models are extremely tail heavy, as all tail fins are solid resin. I will be able to hollow them and also reduce tube wall thickness somewhat, so a 1/6 will come in around 80-90g, which will be within the limits for standard motors. A 1/4 scale could fly on a D or E class motor.....

Hmm, those are quite heavy for their size. A 1/6 is barely larger than minimum diameter for an 18mm motor, and you're already coming in at almost 3 oz (you need to add weight for shock cord, parachute and other stuff.)

My personal suggestion would be to to switch to a paper tube if possible, maybe a BT50 (roughly 1/5.1 scale), and then see how much lighter you can make everything else. That'll also make motor mount and retention much simpler.

Is there a formula or rule of thumb to set a CG?

The rule for stability is to make sure the CG of the loaded rocket (with motor and everything) is 1-1.5 calibers (body tube diameters) behind the center of pressure. You're best way of determining that is to use OpenRocket or Rocksim to create a simulation model.

 

[K'Tesh]

Oh... with the sizes you're working at (which is remarkably small), I'd put the kibosh on the smoke element for a flying version. You don't have the space, and it'd likely be violating a NAR/Tripoli rule on fireworks to achieve at this size. Larger rockets can have clusters where an inverted black powder motor in a special mount is ignited to get a smoke effect (usually for However, ignited from behind it just burns the propellent and delay charges with little (if any) added thrust (read: no bad juju).

 

[miniflyer]

Yes, the current models are small and heavy. They are made for a totally different purpose......they must sustain 200mph flight at 15+G and survive mounted handling after 2 post flight beers, while a few grams extra wont matter much.
The technology enables manufacturing down to 0.3mm wall thickness at superb strength.....i dont think the technology has been used for this purpose to this extent, so it is now up to trials to see how far it can be taken effectively.
I believe i can easily take off 30-40% weight off the current generation, exchanging worry free handling for flyability.

I will try to run some numbers over the following days.

Is there even interest in scale sidewinders?

 

[Cape Byron]

Is there even interest in scale sidewinders?

Is the Pope a modern religious figure?

 

[miniflyer]

The who? Is that the guy who runs around with the candle wick on his head?
Whenever i see him i feel an urge to light the candle

 

[miniflyer]

Ok i ran some numbers.

Will try a 1/5 scale with a C6-5 motor. I see the possibility of a 1/4 or maybe even 1/3 on a D9-3 or -5. Anything larger requires special explosive licencing around here.....

For the crazy ones, a 1/2 would probably work nicely with a G class motor....

 

[cj599]

wanted to share these i took at the pueblo musem