Thales Starstreak build

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DrewW

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Made a bit more progress this weekend. Also ordered some more build materials and several electronic staging/dual deploy gizmos from Apogee, all which Fedex say are due to be here 03Feb. 🤞 :)

Epoxied the BUS fin can motor tube, the retainer and the rear CR into the aft end of the slotted fin can yesterday so it got to cure overnight and allow me to make a start today on installing the fins. I left the fwd CR un-glued so it is removable to allow me to install the screw inserts from the inside through the spacers rings (for he primary attachment to the BUS) and so I can get some internal fin fillets later on. Also cut the fins out of my FG laminated 3mm plywood sheets and sanded them to final size.

Today, I've temporarily installed the fin can and aligned it into the aft end of the BUS. Secured the fin can with 4 small screws to support it and keep it aligned with the BUS during the long process of fin installation. First fin now in place, after notching the base of each fin to promote a good bond onto the MMT. Used the good old "double buttering" technique to get a good amount of JB Weld in there. I'll leave it in the jig for 24hrs to cure so it doesn't creep.

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View attachment 448667


Whilst rummaging for a tool, I found an old off-cut of Ikea curtain track. Although it is a bit too narrow to take a 1010 rail guide or button, I recon it could be cut down and used to make three mini rails for mounting onto the Dart carrier. I wasn't sure what I was going to use for this part of the build, but small, lightweight curtain track seemed one idea. Any other suggestions?

View attachment 448670

View attachment 448671
you’re getting way ahead of me, looks like it’s coming along great! What are you doing with the out of round tube that’s running through the centering ring?
 

BrendanH69

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you’re getting way ahead of me, looks like it’s coming along great! What are you doing with the out of round tube that’s running through the centering ring?
That's in the booster section, which I'm building at the same time for the hell of it. The squashed tube is meant to be a provision for a rear ejection tube for a small chute. I'm not totally convinced I've done the right thing, but will stick with it and see where it takes me. I can always modify it later as it's not critical for the first flying phases of this project.
 

BrendanH69

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Got a Fedex delivery 2 days ago from Apogee. Only took 4 days from Colorado Springs to my front door! Got several electronics items, some build items, and the Estes 18mm motor retainers I couldn't get here.

Finished getting all four fins epoxied into the fin-can. Next job is to remove it and get all the internal and external fillets done too. Also cut the Dart body tubes (BT50's with a wrap of F/glass) down to 380mm and started the assembly of the 18mm motor mounts using the Estes kits and Estes 18mm screw retainers.
Dart MMM pic2.jpg


Also got the hacksaw and Dremel out and cut down that piece of left over Ikea curtain track I found last weekend to give me three nifty little guide rails to use in the Darts. Just need to find or make a suitable rail guides or buttons for them as they are smaller than 1010, so either I've got to make something or open them up a bit.

Dart MMM pic1.jpg


Will be playing with the various electronics ( RRC3 + accessories, a staging timer, and 2 Micropeak altimeters) this weekend to understand them and check their operation.
 

DrewW

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So I stumbled into being the recipient of some PML 3", 4", and 6" tube today. So it looks like my first cut at the booster will probably be a 60% scale to check out fabrication and air start methods. It looks like a BT5 would be really close to the right OD for a matching scale dart. I'll probably make one or more of those as well to test out the stability and mechanics.

At the same time I stumbled into some black powder which has been hard to find lately, so I'm going to look at fabricating the PVC Spider (a la Team Meatball Rocketry) being very careful with the differences between BP and pyrodex. I've got the owner of my local rocketry shop (Rocketry Works) on board with fabricating unique items via in house 3D printing or laser cutting if necessary.
 

BrendanH69

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Finished all the fin can internal and external fillets at the weekend, so moving on to the s inserts for attaching it next.

AA6C2179-34B4-4CD9-A514-4143017080D2.jpeg


After that I think I’ll build one Dart and then also move onto the next hard bit - the nose/Dart carrier and ignition spider too
 

DrewW

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Was just working on getting pieces together for the spider. If using 2” schedule 40 a 2-1/4” hole saw is just about perfect for the caps. Only very minor sanding needed for a clean fit.
 

BrendanH69

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Started on installing the four aft fins on the first trial Dart ("Hitile").
Made a little fin jig. Cut the four fin slots in the body tube with a thin cutting wheel on the Dremel (the knife was not as clean a cut on the inside surface) and then CA'd the motor mount into position. Due to the bevelled leading edge, cutting the tab on the first fin resulted in some chips breaking off from the root tip, so I brushed the leading and trailing edges with some CA to stiffen them up, and that seemed to work.

Dart Fin Install pic1.jpg



Regarding the Spider, I'm a little concerned about it's performance in flight.
Obviously, the spider is normally static when it is operated and it is normally left back on the launch pad. In our designs for the Starstreak, it gets to go flying and experience between 2G and 4G's at Bus launch.
What's your thoughts on this, Drew, particularly keeping the pipes aligned with the Darts' motor nozzles and keeping the Darts' motors close enough to ignite, despite any tendency for them to maybe want to "drag separate" away once the motor on the BUS burns out?
 

DrewW

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Regarding the Spider, I'm a little concerned about it's performance in flight.
Obviously, the spider is normally static when it is operated and it is normally left back on the launch pad. In our designs for the Starstreak, it gets to go flying and experience between 2G and 4G's at Bus launch.
What's your thoughts on this, Drew, particularly keeping the pipes aligned with the Darts' motor nozzles and keeping the Darts' motors close enough to ignite, despite any tendency for them to maybe want to "drag separate" away once the motor on the BUS burns out?
Great progress!

I have similar concerns about the Spider, because it is clear the bus is going to want to drag separate from the hitiles. So I can only think of four options: (1) set a delay to be only slightly longer (maybe 0.25 sec) than the thrust curve burn data for the bus motor; (2) select a bus motor that has a long taper to the burnout and initiate during the thrust "tail" (see thrustcurve.org visual below for Estes C5 motor), this long thrust tail should counter the desire to drag separate; (3) use an onboard accelerometer to trigger after period of thrust followed by return to 1g environment (again +0.25 sec, maybe shorter); (4) lastly, by adding friction to a point of attachment between bus and hitile, you can add a retention force which will slightly overcome forces at play in drag separation, this is similar to the friction fit techniques of stages or sections in use, but I would definitely stick to lightly retained rather than have a shear pin.

1613045725338.png


With this C5 motor there is a good 1.5 seconds of near constant low thrust, something like this on the HPR side could be a useful way to stretch out the critical window of time for initiation.
 

DrewW

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Looking in HPR motors on Thrustcurve.org the following L1 motors look interesting (without having used any of them in simulation to verify they're fast enough off the pad)

RATT H70
RATT I90
CTI 614I100
AT I59
 

Nytrunner

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Looking in HPR motors on Thrustcurve.org the following L1 motors look interesting (without having used any of them in simulation to verify they're fast enough off the pad)

RATT H70
RATT I90
CTI 614I100
AT I59
The first 2 are Rattworks hybrids (maybe even tribrids). The are OOP and far more trouble than you want for this project
 

BrendanH69

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Looking in HPR motors on Thrustcurve.org the following L1 motors look interesting (without having used any of them in simulation to verify they're fast enough off the pad)

RATT H70
RATT I90
CTI 614I100
AT I59
geez... an I motor would literally put it out of sight I recon! Will simulate it in OR tonight.
I’ve been designing it around CTI 38mm 115G motors in both the booster and the sustainer (the BUS). 24mm G motors are an option for me too, but I can’t seem to get my hands on any long burn versions.
Want to keep it in easy visual range to get to see the Hitiles seperate. This project is about being challenging but fun and show too!
Will look at the thrust curves of the available motors and see if there are optimal ones with suitably long tail offs in thrust.
 

DrewW

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The first 2 are Rattworks hybrids (maybe even tribrids). The are OOP and far more trouble than you want for this project
Thanks for catching that. I didn't realize that's what Rattworks did. Guess that means this particular solution space is pretty limited in those larger sizes. And looking at my simulations for a 5" OD booster when I kicked this all off, a CTI G115 is even a little more motor than I want
 

DrewW

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Not expecting this to be perfect but I prototyped an initial attempt at the spider I’m going to be using for R&D and if it holds together long enough I may also use it to test fire a 3x18 cluster project I’ve been working on.

1613113471168.jpeg


Pictured is combustion chamber, top plate and bottom plates coated in epoxy clay. Ugly but hopefully sufficient. I learned a lot of things about what not to do in this first attempt.
 

BrendanH69

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I learned a lot of things about what not to do in this first attempt.
Do tell, young man!

My learning points so far on the trial Dart build with plywood fins & canards are:
  • The Estes 18mm screw on retainers were well worth the wait and far better that the ones I was trying to make.
  • CA soak the plywood bevelled edges to minimise chipping/breakage.
  • A Dremel with a thin cut wheel is far superior for cutting the fin slots in the glassed BT50 cardboard tube versus a craft knife.
  • Don't cut the fin tabs they way I did to match the MMT. Instead, make longer slots in the body tube (past the fwd end of the motor mount), leave the tabs full root chord length to go through the wall and notch out the tabs only for the MMT centering ring bits. This will also help avoid tip/edge chipping/breakage.
  • Depending on weight & CofG impacts, consider F/Glass sheet for the fins and canards next time. More resilient to breakage, but weigh more.
  • Based on actual build weights versus the OR simulation with an Estes B6-4 motor in it, my Dart (at approx 114% scale) will need between 35g and 38g ballast in the nose cone to give it a 1 CAL stability forecast.
 

DrewW

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Do tell, young man!
(1) As designed, the spider was for a 7x18mm cluster which means the top plate is probably the wrong size for this project altogether (but fixable), but also that the spider tubes are placed incorrectly. So measuring and or math will be important in setting up for a different cluster configuration; don't forget to account for wall thicknesses if clustering.

(2) Stand-off tubes may or may not be "important" depending on how you implement the design and where it's being used; to support a 3x18mm it was important, to support 3 individual 18mm rockets maybe not.

(3) Not sure if lighter ply will work (going to find out though) but have a sheet of 1/4" (6mm) ply on hand

(4) Drill sizes were in decimal inches...assuming this is useful for CNC or laser cutter, sizes are 5/32" (4mm), 1/8" (3mm), and 1/16" (1.5mm)

(5) Designer called out #6 (machine) screws, not M6 like I originally though...big difference.

(6a) Convenient hole saw sizes were 2 1/4" (60mm) & 1" (25mm); for the OD of the ring you have to consider the kerf of the hole saw

(6b) Fly cutter was a terrible tool for making the plates, but was a useful-ish tool for scribing circles on the plates once I had them cut

(6c) Lock your wood in place! I found freehanding made things way more difficult and dangerous with my drill press, thankfully the lessons learned didn't require stitches or even band-aids. but locking the wood down also makes the co-centration easier between center drilled holes

(7) On the mid layer, I found it helpful to half cut the OD, then come back to remove the ID, then follow with fully cutting the ID

(8) on the bottom layer, I did the same, but the ID is just enough to create an annular depression to catch the BT-50 tube.

(9) thinned JB Weld brushed on with a flux brush might be a better way to go than epoxy clay as far as the lower section and power cup are concerned
 

BrendanH69

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Good feedback Drew.

ref 2) - I'm not decided on the standoff/support tube yet. Will mull it over.

ref 6) a b and c - Being a non-CNC or 3D printing guy, I'll rough out my circular plates and bulkheads with holes saws and finish to size in my sanding jig. Would recommend the 6mm ply. Safety first. I'm going to use F/Glass sheet for the spider rather than ply.

Ref 9) +1 on that. I've brushed the inside of the BUS body tube next to the recessed motor retainer with non-thinned JB Weld as a heatshield, so I was going to do the same with the spider.

Is it just me, or is the BP pan in the spider design looking too wide for such a small amount of BP? Maybe I need to re-read the report again?
 

DrewW

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Good feedback Drew.

ref 2) - I'm not decided on the standoff/support tube yet. Will mull it over.

ref 6) a b and c - Being a non-CNC or 3D printing guy, I'll rough out my circular plates and bulkheads with holes saws and finish to size in my sanding jig. Would recommend the 6mm ply. Safety first. I'm going to use F/Glass sheet for the spider rather than ply.

Ref 9) +1 on that. I've brushed the inside of the BUS body tube next to the recessed motor retainer with non-thinned JB Weld as a heatshield, so I was going to do the same with the spider.

Is it just me, or is the BP pan in the spider design looking too wide for such a small amount of BP? Maybe I need to re-read the report again?
Thinking the same, but I haven’t played with BP much. Possibly thinning the layer to increase reaction cross section? Maybe just a peculiarity of using an Estes igniter for the cumbustion?
 

BrendanH69

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Finished the fins and canards initial attachment to the first Dart body today. Just need to do a few tiny fillets and also give the canards a tip to tip F/Glass treatment.

Did a bit of a mock-up of the Dart carrier and some uPVC pipe fittings (for 50mm pressure pipe) that looked likely candidates for the Spider housing. However....by my estimates, even though the OD of this fitting is in the region of 70mm, it still won't be wide enough to have straight pipes into the Dart motors. If that's right, then Ill need something with at least 90mm ID.

The radial position from the rocket centreline of the Dart's BP motor nozzle depends on:
  1. How far off the mini rail guides the Darts will stand-off (the rail guide solution).
  2. How well the Darts will stack around the carrier and whether their fins touch when in position.

Dart trial fit pic1.jpg


Dart trial fit pic3.jpg


Dart trial fit pic2.jpg
 

BrendanH69

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Most of these CAD/3D renderings can be misleading, as well as including another type of Thales high velocity missile. Only the last photo is of the actual Starstreak system. Its a great photo which I'd already had on my design "mood board" as it highlights the presence of 4 aft fins (not 3 as per the renderings) and 2 symmetrical canards. It also highlights the bevelled leading and trailing edges of all the flight surfaces and it can offer a guide to help set the proportions and scales in our design process. Supposedly, the Hitiles are 396mm in length and 22mm in diameter.

1613275226955.png
 

BrendanH69

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Slow but steady progress.
Got all 5 of the screw inserts from the inside of the the fin and through into the Fwd spacer ring. Then aligned them with the screws in from the outer edge of the aft BUS spacer ring. Fin can is now in place and removeable for future changes and for any issues running an airstart ignitor to the BUS motor.

Continued construction of the Darts (Hittiles) with the last set of the aft fins epoxied in place tonight. Added 38g of ballast to each nose cone (lead shot +epoxy) as I went along. I've got the last two sets of canards to start fixing, then fillets on the 2nd and 3rd Darts, then tip to tip F/glass on all 3 sets of the canards.

Dart construction continues pic2.jpg


Dart construction continues pic1.jpg
 
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