# Full Scale Aim-4 Falcon Missile

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#### burkefj

##### Well-Known Member
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Been giving some thought to working on an aim-4D, decided to start doing some openrocket/rocksim simulations..

I don't have any good drawings/dimensions other than it will be full scale, approx 78" long and 6.4" diameter, which will work well for a 6.25" centering ring and 2mm skin. This is good for my foam building technique since the fins are not right at the bottom of the model, and the CG needs to be further forward. I think this will work out well, about like my fullscale hellfire but with less/no nose weight required.

I'm going to model based on these pictures, I believe the nose section on this is a made up unit, but since it has a straight transition it will make it easier for me to do using foam stringers and sheeting....there I go being lazy again. It should wind up near 5.5 pounds rtf.

Frank

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#### mpitfield

##### Moderator
Staff member
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Global Mod
Wow Frank you do pick some nice looking models. And your building technique is pretty unique for HPR, I would love to see one of these fly one day in person.

#### Barkley

##### Well-Known Member
On John Coker's site he does a great write up of his visit to the range in Churchill Manitoba, and he has a pic of two missiles just hanging out in the range that look a lot like that:

http://www.jcrocket.com/churchill.shtml

#### K'Tesh

##### OpenRocket Chuck Norris
Best I could find for dimensional drawings of it was found on Wikipedia (below).

#### rharshberger

##### Well-Known Member
When I get back home tonight I will check, I may have a dimensioned drawing.

#### burkefj

##### Well-Known Member
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Thanks Jim, I was using the drawing you got on wiki as my swag for the openrocket file...but it wasn't super..Rich, let me know if you find anything. Barkley, thanks for the extra pictures.

Got a few centering rings, misc parts, and made the nose using the styrofoam ball I had left over from my hellfire.

Frank

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#### burkefj

##### Well-Known Member
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Ok here is with the boattail...Cut all the centering rings, found some lite ply at the craft store for a great price with two coupons...so my rear end ply weight isn't as much as I was expecting.

Frank

#### rharshberger

##### Well-Known Member
The September 1970 Model Rocketry has scale data for the AIM-4E Falcon, I have a PDF copy of it if anyone is interested.

#### burkefj

##### Well-Known Member
TRF Supporter
Rich, why don't you post it here as an attachment?

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#### burkefj

##### Well-Known Member
TRF Supporter
Ok, cut the stringers today, notched them 1/2" so that they would lock into the centering ring slots and self align and dry assembled it. For the boattail, I used a piece of spare pml 3" tubing to transfer landing loads to the upper ply centering ring that will have the rail button attached, this will keep landing from crunching the boattail. i'll need to add the stringers that go from the main body up around the parachute tube lower half, then the centering ring forward will have tapered stringers to the nose. I put a lite ply centering ring on the parachute tube to protect the foam from the kevlar line, I've found in my hellfire if the body has any momemtum and the kevlar line goes tight against the body during deployment it can do a little crunching of the transition where it gets wider, so the ply plate will protect against that. Just the foam airframe weight is 7 ounces.

Frank

#### rocketguy101

##### Well-Known Member
There is discussion elsewhere on this forum about letting those forward fins "swivel" to reduce their effect on the CP, might help reduce nose weight/CG issues (you mentioned in the "skin" thread about making sure your parachute weight was way forward...)

#### rocketguy101

##### Well-Known Member
BTW when this puppy is done, you could have fun hauling it to launch...

#### burkefj

##### Well-Known Member
TRF Supporter
Yes, I saw that discussion on the Talos where the forward fins are really large. On this model the forward fins are relatively small and the rear are large and based on my CG calculations I'll have no problem getting the CG ok without having to do the swiveling fins. But eventually I'll try that on something with larger forward fins I'm sure.

There is discussion elsewhere on this forum about letting those forward fins "swivel" to reduce their effect on the CP, might help reduce nose weight/CG issues (you mentioned in the "skin" thread about making sure your parachute weight was way forward...)

#### KenECoyote

##### Well-Known Member
TRF Supporter
Dang! That's one COOL looking missile to model! op:

#### burkefj

##### Well-Known Member
TRF Supporter
Sheeted the boat-tail and the forward transition. Here is the stack so far. Dang, it's pretty long....
So far I've only used one $10 sheet of depron for all of the centering rings and stringers plus some scrap that I had laying around. I was going to order the 29mm tube and 4" coupler from wildman but it was going to be$20 shipping because they drop ship the 29mm tube from loc, and send the coupler separately. I found the same tubing for $3 per tube for 34" length, plus the coupler for only$6 shipping from BMS so I ordered from them.
I was able to use up a bunch of my 3/32" scrap for the smaller centering rings and found a deal on lite ply at the craft store for \$4/sheet of 12x12 so that covered my big centering rings. I had a recycled retainer from an rc rocket plane I converted to electric, and had the styofoam ball left over from my hellfire, and the screw eyes and wiring left over from my Titan II I just finished. The forward fins from lexan I had left over from my Mercury atlas. I'll share the chute and altimeter with my other models. So far this is turning out pretty cheap.

Frank

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#### burkefj

##### Well-Known Member
TRF Supporter
Got up early and made the first set of fins. Lower set has carbon spar and a trailing edge to protect against landing damage, the upper fin has an angled carbon spar for the same reason. there are slots in the root that will glue/lock into each centering ring. Lower fin weighs 7/8 oz and the upper 3.5 oz, total weight so far is 26 ounces.

Frank

#### dixontj93060

##### Well-Known Member
Looking very nice!

#### burkefj

##### Well-Known Member
TRF Supporter
Got the tubes today, the blue tube coupler is very nice, cut it and made the shoulder for the nose, glued in the stuffer tube and centering rings for the parachute bay and CA'd all of the joints on the frame. I haven't glued in the tail cone or the parachute bay yet so I can do the sheeting and trim the ends, then install the tail cone and parachute bay with tranition afterward. Total weight now is 33 oz
You can see the mounts for the rail buttons on the ply centering rings, after sheeting I'll find the holes and install the rail buttons.

Frank

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#### K'Tesh

##### OpenRocket Chuck Norris
I wish I had the time and money to do something like this myself... In the meantime, please keep posting lots of pics. So, I can live vicariously through you.

#### mpitfield

##### Moderator
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Global Mod
I am amazed at how accurate all of your cuts are, do you cut all your foam by hand?

#### burkefj

##### Well-Known Member
TRF Supporter
Thank you. Yes, all the cuts are with straight edge and exacto. For repetetive things like the centering rings, I cut the ply thrust plate, then used it as a template to cut the foam. For the stringers, I just used the 2" wide straight edge to cut the strips, then I glued and taped them together to get the length I needed.

I cut one CR and one stringer with the slots where I wanted and then used them as a template to cut the rest. Just being careful to not cut the template with the exacto. I used thumb tacks to hold the template in place on the piece I'm cutting to make sure it doesn't slip. The foam can compress slightly, so you can cut slightly undersized and then press fit them together for a tight fit.

It actually goes pretty quick.

What takes more time is thinking about how the fins are going to lock in place, landing loads, where to put carbon etc. Also, I learned to put a double wide stringer down the back so that if I make a little mis-alignment of the sheeting, I have plenty of gluing surface to line up to. It's really hard to line up and get a perfectly straight 6mm stringer 70" long and then line up a sheet down the 3mm center and have a good seam. I used to try to create shroud templates, but I always was slightly off due to the thickness of the foam, getting them started perfectly straight etc. Now, I just do the transitions separately, applying the contact cement to a sheet and rolling the structure onto the sheet, then trimming the ends and seam afterward.

Frank

#### Daddyisabar

##### Well-Known Member
As always, very cool.

#### burkefj

##### Well-Known Member
TRF Supporter
Finished the sheeting last night, total weight with sheeting, nose, tailcone, and retainer is 38 oz.

Frank

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#### burkefj

##### Well-Known Member
TRF Supporter
Put a flange on each rear fin and then cut the slots and dry fit them. The flange is sort of scale, and helps keep the skin from buckling/puckering around the fins.

#### burkefj

##### Well-Known Member
TRF Supporter
Ok, added the flanges and slotted the structure for the upper fins and dry fit them, starting to look like a missile now. I'm tired and have to console my daughter after the Rousey/Holmes fight......

#### rharshberger

##### Well-Known Member
The Falcon looks great Frank, another stellar build.

#### KenECoyote

##### Well-Known Member
TRF Supporter
WOW! That's an impressive and beautiful rocket! :clap:

Amazing work!

#### burkefj

##### Well-Known Member
TRF Supporter
Thanks all, I appreciate that.

Cut the altimeter bay, since this is a 6.4" diameter rocket, I don't have sufficient space between stringers to fit my 38mm altimeter pod inbetween a single section, so I had to cut a clearance into one stringer so that the altimeter pod would fit inbetween two sections. Made the door from .015 styrene sheet, a 6mm depron lip and some magnets. You can see a small .03 styrene disk on the body tube, that is to reinforce where the rail button goes so I don't screw down too hard and crush the foam skin. the line above the door marks where the upper fins will go.
You can see the 29mm stuffer tube, the wiring will route through the stuffer tube into the parachute bay through a little cap, the cap will seal off the stuffer tube from the ejection charge, the wiring to the deployment charge will to through a tiny hole in the cap. I leave enough wire so that I can pull the cap all the way out of the parachute bay to tape connect and tape the charge on top, then push it back into the stuffer tube and cap it off.

Frank

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