Estes Pro Series Terrier Sandhawk

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kuririn

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It was announced a few days ago that my states' stay at home restrictions have been extended to the end of May!
Either I'll have put a serious dent in my build pile by then or I'll have gone crazy.
So here's another build. Picked this up from another forum member.
Vintage and long OOP.
Can be launched either as a single stage Sandhawk or single stage Terrier/Sandhawk.
But not as a two stager (although I am exploring that).
Parts:
0501200826[1].jpg


Tubes are yellowed with age but undamaged.
Fins, fin can and nose cone are all plastic. No wooden external parts.
My kind of rocket. Finishing should be a breeze.
TBC
 

K'Tesh

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I wish they'd come out with a new Sandhawk kit, and while they're at it, create a new nosecone for it. I hated the glue together injection molded parts that came with the kit. For some reason the plastic they used for it was really hard to get to adhere well, and the tiny hooks that lock the nosecone to the payload section were quite fragile.
 

MarkB.

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For what it's worth, the paint scheme in the instructions was not used on the actual vehicle. The paint is for a single stage Sandhawk test round flown out of Tonopah, Neveda. Pictures of an actual Terrier-Sandhawk are tough to find; I have seen both red and white Sandhawk sustainers usually with extended payload sections. I'll see if I can find picures. Also, use the metal antennae. The instruction technique is unnecessarily difficult, just bend a short section at the end, heat the end with a match and push it into the plastic, secure the wire with a glob of epoxy from the inside.
 

kuririn

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Motor mount was assembled and filleted. The fin can half shown here is only dry fitted for placement. If your measurements are off by one mm. the fiber rings will not fit into the narrow slots.
0501202032[1].jpg


Nose cone was glued together and rubber banded,
0501202122[1].jpg


These are the tabs that K'Tesh was referring to. After putting in the clay ballast and foaming it in, the tabs only have to work long enough for me to glue the nose cone to the payload section.
0501202124[1].jpg


Problem: this is what I found when dry fitting the two payload sections together.
0501202039[1].jpg


0501202039a[1].jpg


The two halves are warped and out of round.
Guess the years of storage have not been kind.
Working on a solution.

And finally for tonight, assembled the included fiberboard jig for the antenna placement.
Estes thinks of everything.
0501202043[1].jpg


MarkH, I decided to use the plastic antennae. I have formed metal wire on both the FSI Sandhawk and the smaller ASP mini Sandhawk. Glued in balsa nose blocks behind the tubing to provide support, then drilled holes and epoxied in the antennae. But for this model since two sets of antennae are supplied, the "easy way out" side of me has won the day.
As for livery, I found a couple of pictures online of operational rockets. They are either all white or mostly white.
B-O-R-I-N-G.
And the Sandhawk sustainer can either be flown singly or in tandem with the Terrier booster, so I'm going with the customary livery.

Will let the glue dry overnight on the mount and nose cone.
TBC
 

kuririn

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The clay nose weight was tamped into the nose cone
0501202308[1].jpg


And covered with Gorilla glue and a few drops of water. After a few minutes it started foaming.
0502200731[1].jpg


And after a few hours it had cured hard and filled most of the nose cavity.
That clay weight ain't going anywhere.
0502201111[1].jpg


The Sandhawk fin can halves were cemented to the mount and rubber banded together.
0502200733[1].jpg


I used the clamp from my Kuhn tube cutter to correct for the warpage in the payload sections.
Glued the two halves together and rubber banded. Glued nose cone in and dry fitted body tube to maintain roundness while drying.
0502201159[1].jpg


Have to let the fin can and payload section dry.
More later.
 

kuririn

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The Sandhawk fin can was glued to the airframe and the fins were tacked on with cement.
Instead of the tri-fold shock cord anchor I tied a kevlar leader to the motor mount.
0503202109[1].jpg


Assembled the Terrier motor mount:
0503200903[1].jpg


And cemented the Terrier fin halves together
0502201621[1].jpg


While that is drying, I started gluing the chute snaggers, I mean antennae using the previously assembled jig.
0503202117[1].jpg


One down, six more to go. ;)

And under the category of Auwe (Hawn)
Crikey (Aussie)
WTF (Universal):
After gluing in the engine block on the Terrier motor mount, I used a spent E12 engine casing to check for and remove any excess glue at the front of the engine hook and this is what I found:
0503202128[1].jpg


Yes, the casing is flush to the front tab of the engine hook.
0503202128a[1].jpg


The engine hook is too short! It's 3.5 in. long, should be 3.75 in. long.
Jeeeeeeez.
Good thing I caught it before gluing in the motor mount.
Will try re-bending the hook to the correct length.
If that doesn't work I'll just cut it off and use aft end tape wrap.
Or maybe a plastic 24mm screw on retainer.
Laters.
 
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K'Tesh

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After gluing in the engine block on the Terrier motor mount, I used a spent E12 engine casing to check for and remove any excess glue at the front of the engine hook and this is what I found:
View attachment 415052

Yes, the casing is flush to the front tab of the engine hook.
View attachment 415053

The engine hook is too short! It's 3.5 in. long, should be 3.75 in. long.
Jeeeeeeez.
Good thing I caught it before gluing in the motor mount.
Will try re-bending the hook to the correct length.
If that doesn't work I'll just cut it off and use aft end tape wrap.
Or maybe a plastic 24mm screw on retainer.
Laters.
Doh, That kit was released during the days of the short-lived short "E" motors. I'm not sure but I'm guessing that they had a reputation for failing, and later the current length came out.
 
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kuririn

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I used two pliers and first straightened out the hook, then bent it to the proper length.
0504200554[1].jpg


Problem solved
0503202228[1].jpg


The antennae have all been cemented in place. The jig made it easy.
0504200616[1].jpg


And fins have been filleted.
0504200617[1].jpg


Launch lugs were glued on with standoffs and recovery gear was assembled.
Sandhawk assembly is complete.
0504200628[1].jpg


Next: Terrier assembly.
TBC
 

kuririn

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Glued the engine mount into the booster body.
Tacked on the TTW fins with plastic cement.
0504201033[1].jpg


Close-up of the plastic transition. Slot for sustainer engine hook.
0504201242[1].jpg


The kit is only designed for single stage flights but I am leaving the option open for modifying this to gap staging. The top shoulder of the transition would have to be cut off as this friction fits into the sustainer motor tube. And the top opening would have to be slightly enlarged to nest the aft end of the sustainer motor. Distance between motors is approx 13" or so. Will do single stage shake down flights then make a decision.
Has anybody modified this into a two stager? Search comes up empty.

Vent holes for gap staging would emulate the real Terrier booster.
0504201242a[1].jpg


The kit comes with an 18" nylon chute for the sustainer or sustainer/booster body and a 12" chute for the payload section and nose. No dimensions given for launch plug placement other than "glue the launch lugs near the ends of the body tubes".
So assembly is complete.
0504201313[1].jpg


No wood to fill and the spirals are pretty shallow, so this is going straight to primer/sanding/basecoat.
Will post pics after finishing.
Laters.
 

5x7

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Doesn’t the hook hold them together?
 

EXPjawa

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The hook on the Sandhawk clips it to the Terrier. Its a tough one to release to separate the two, or at least mine is. If that's the hook that was rebent, then I don't think that latch on very well.

Nice job with the antenna jig. They were probably the most problematic detail of the model for me; they're prone to breakage, mine came off long gone. I've reglued them a few times, but gave up. I think I still have two of them in my desk drawer...
 

kuririn

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Doesn’t the hook hold them together?
The hook slides into the notch but the fit isn't tight enough to prevent separation of the booster and sustainer when the chute jolts open. And then you would have a Terrier booster free falling to the ground. Instructions say to wrap tape around the front of the transition to ensure a tight friction fit.
Here's the interesting part. Instead of gluing the short tube to the transition and cutting a notch for the engine hook, I dry fitted it and experimented with sliding the tube up and down the sustainer motor tube and transition.
In the full up position, the hook slides out and the Sandhawk is easily removeable from the Terrier.
But, when the short tube is in the full down position, they are locked together.
For single stage flights I am adding that mod to the design. Adds one more layer of insurance other than just friction fit. And a tape wrap on the short tube wouldn't hurt either.
If I go two stage, the short tube will act as a stage coupler. The hook recess in the transition would also have to be opened up to allow the hook to be non binding.
Hard to explain, here's some pics to illustrate:
Short tube full up, hook easily slides out.
0504201523[1].jpg

0504201524[1].jpg


Short tube full down, hook slides up and out but is restrained by the tube.
Both sections are kept from separating.
0504201524a[1].jpg

0504201525[1].jpg

Easier to visualize with the parts in hand though.

The hook on the Sandhawk clips it to the Terrier. Its a tough one to release to separate the two, or at least mine is. If that's the hook that was rebent, then I don't think that latch on very well.
Mines comes apart with a good tug. Not enough peace of mind to risk separation on that alone.
Thankfully the funky short hook that only works with extinct motors was for the booster mount.
I anticipate that the antennae will either snag the shroud lines or be damaged upon landing.
Good for at least one poser shot though.;)
 

K'Tesh

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Nice job with the antenna jig. They were probably the most problematic detail of the model for me; they're prone to breakage, mine came off long gone. I've reglued them a few times, but gave up. I think I still have two of them in my desk drawer...
Amazing what you can do with a paper clip... Jus' sayin'.
 

MarkB.

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Here's the link to the two-stage conversion. It's about the twelvth or thirteenth article from the top. Rockets of the World has a "correct" red Sandhawk two-stage color scheme. The only real difference is the fins are grey and the payload bay as a black band rather than the metallic green portion.

www.rocketshoppe.com/tips.htm
 

kuririn

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Thanks for the link MarkB. The article details electronic air starting, but I was wondering if anybody has successfully gap staged this model with BP motors. What would be the limit for reliable gap staging in terms of distance apart for the booster and sustainer motors? Has anyone done this, or do I have to do some static tests?
 

Nytrunner

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Nice build! Especially dealing with the aged plastic components.
Was this the 4th of the original Pro Series kits released after the Patriot, Impulse, and (3rd one I forget)?

I believe @BABAR has reported success with long staging in excess of 40" (50?)
 

kuririn

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Nice build! Especially dealing with the aged plastic components.
Was this the 4th of the original Pro Series kits released after the Patriot, Impulse, and (3rd one I forget)?

I believe @BABAR has reported success with long staging in excess of 40" (50?)
Thanks! From another thread, I believe the original Pro series was Patriot, Impulse, Maxi Force, Terrier Sandhawk, and Jayhawk. I'm hoping that Babar can provide some insight to long gap staging.
 

Nytrunner

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Maxi Force, that was it. I confused with the Maxi Brute lineup and discarded the name candidate.

Man those antennae look like an exercise in misery. Wonder if you can replace them or reinforce them with wire
 

kuririn

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Man those antennae look like an exercise in misery. Wonder if you can replace them or reinforce them with wire
Nah, I've done wire on the bigger FSI Sandhawk.
Two sets were provided in this kit, so I went with a stock build.
If they break off, so be it. No biggie.
 

kuririn

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Primer went on.
It showed some gaps that needs to be filled.
Using white Squadron putty.
TBC
0606201334[1].jpg
 

kuririn

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While browsing through Alway's Rocket of the World I came across a black and white picture of an actual round on a launch rail. It's a Sandia photo courtesy of Estes and appears to match the Estes face card color scheme.
Also Mr. Alway's dimensional drawing and color scheme matches the face card, so that's what I'm going with.
TBC
 

Charles_McG

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I’m jumping back up the thread for a moment, up to the interstage.

Does anyone have more info/details on the Terrier interstage? I’ve searched, but can’t find. I’m really curious about those vents, and the internal structure.

I’ve read that the Terrier booster drag separates, at least for sounding rockets. And that it has a clamping system that helps keep the stack stable. Both were viewed as positives by the writers. I’ve seen pictures of the Terrier booster on sounding rockets with and without drag plates.
So what are the ‘vent’ holes identified in the instructions above for? Close up photos show them to be flat disks with a bracket on each side. There’s a pipe attached to a short cylinder on one side.

I realized this morning that they must relate to the original flight plan for the RIM-2 missile. Low altitude, 10-15 mile range, Mach 2-3. Way different than a sounding rocket flight. So was the RIM-2 drag separates, or maybe blast separates, and those vents have burst disk covers? Or a system to burst them and make more drag at the appropriate time?

Then what about the internals? Nike interstages seem to be machined to fit the nozzle of the stage above. But I’ve never seen Terrier pics with the stages apart.
 
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