Stellar Dimensions Inc. (SDI) kits

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kuririn

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Picked up 5 SDI kits from EBay a few weeks ago. Finished 2, the Gyro Nomo and Phalanx, when it occurred to me that I should do a build thread of one to highlight some unique aspects of these designs.
0331201922[1].jpg
l, Gyro Nomo
r, Phalanx

So this is build 3, the Vr-T-Go.
Header card, instructions
0331201931[1].jpg


Parts
0331201920[1].jpg


The kits have interesting laser etched designs on the body which I didn't want to cover up with paint. I tried using Sharpies on the first two builds but the color was too strong. So I tried using an orange highlighter on this one, with much better results
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First the winglets are laminated with plywood overlays
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And put under a weight to dry overnight without warping
0331202215[1].jpg


And the main body was assembled, rubber banded and left to dry overnight
0331202215a[1].jpg


TBC
 

kuririn

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This morning I assembled the nose cone, rubber banded it, and set it aside to dry.
0331202328[1].jpg


The 2 launch lugs are assembled from thin plywood. Each half is glued together then set aside to dry.
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There are two removable motor mounts, 18 & 24 mm.
Glued the two halves of the top and bottom of each mount together.
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And set those aside to dry.
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After drying, assembled the 18mm mount
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And the 24mm mount.
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These are also set aside to dry.
TBC.
 

kuririn

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I wanted to share this cuz I find it to be really interesting.
This kit comes with two chutes. The shroud line attachment method is unique.
These are the adhesive tabs and plywood eyelets.
0401202133[1].jpg


The plywood is placed inside the tab
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And the tab is folded over onto a corner of the chute
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Shroud line is attached to the plywood eyelet.
Should be very strong, less likely to rip out compared to paper reinforcements.

CORRECTION: I said previously that there are 2 motor mounts. 24 and 18mm.
Actually it's 2 18mm mounts, one for BP A,B,and C motors, and another for composite Ds(?).
Last time I checked the dimensions for the AT 18mm D motor was the same as BP motors, so don't know why the separate mounts. Oh well.
Had to do a lot of sanding on the mounts to get a nice fit. This is how the motor is loaded
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And the retainer ring is twist locked into position
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Already a corner of the aft end has broken off! Will have to repair that.
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Launch lugs, wings and winglets, ventral and dorsal fins have been glued on.
Only fillets need to be done so assembly is mostly complete.
0402200529[1].jpg


Pros: Unique, one of a kind kits with some unusual construction techniques.
Cons: Shock cord is too short. Many elements seem kinda flimsy, like the shock cord anchor and motor mount and motor retention elements.
Hope you guys found this insightful.
Two more SDI kits to go, should keep me busy during lockdown.
Sayos.
 

neil_w

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Fascinating, almost a complete reinvention of how to build a rocket.

Are you sure the lug ring is on right? As shown, the rod will go right through the retainer tab. Seems like it probably wanted to be flipped around so the rod was centered on the side.
 

kuririn

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Yeah, I dry fitted it before I glued it.
If I reversed it the rod would go right through the ventral fin.
The retainer tab is a little long, it can be trimmed back a skosh.
Here's a better pic showing the tiny fin.
0402200828[1].jpg
 

mbeels

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Wow, that is different. I like the parachute shroud attachment method. But that tab on the body for the locking motor mount would be quite weak with the grain going in that direction. But interesting, nonetheless.
 

neil_w

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One thing I just noticed: there's no core body tube inside this thing. That means the wood box is expected to contain the ejection charge. Maybe not a problem but somehow surprising to me. It's all balsa I presume?
 

kuririn

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One thing I just noticed: there's no core body tube inside this thing. That means the wood box is expected to contain the ejection charge. Maybe not a problem but somehow surprising to me. It's all balsa I presume?
Yeppers, in reading reviews of another SDI kit (Zanadune) it seems that ejection gas leaking backwards and out sometimes results in the laundry not deploying. A snug fit between the walls of the motor mount and body as well as between the front of the mount and the bulkhead is key I think. We'll see how it goes. I may have to add a tube later.
One thing I didn't take pictures of - there are 4 bulkheads between the motor and the laundry. So perhaps they will baffle the embers and I may not need wadding? Plus they add structural strength to the main frame.
 

BABAR

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Yeppers, in reading reviews of another SDI kit (Zanadune) it seems that ejection gas leaking backwards and out sometimes results in the laundry not deploying. A snug fit between the walls of the motor mount and body as well as between the front of the mount and the bulkhead is key I think. We'll see how it goes. I may have to add a tube later.
One thing I didn't take pictures of - there are 4 bulkheads between the motor and the laundry. So perhaps they will baffle the embers and I may not need wadding? Plus they add structural strength to the main frame.
IF you can keep it contained, might be a good place for Gorilla Glue polyurethane. that is a big IF
 

kuririn

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IF you can keep it contained, might be a good place for Gorilla Glue polyurethane. that is a big IF
Yeah, if ejection leakage is an issue I may permanently glue one of the mounts in and forego interchangeability.
We'll see.
Those launch guides look pretty delicate.
Not only the launch guides. The motor mount, L slots holding the retainer ring at the aft end of the rocket, shock cord anchor.........
May be one reason they're no longer around.
 

hcmbanjo

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Here's a record of my SDI Xanadune two flights:

SDI 1.jpg

1. "Good, straight boost. During the coast phase, you could see the rocket spinning from the angled fins. At recovery, only the nose cone blew. the parachute stayed in the narrow square midsection. A fin was broken off on landing - easily repairable. After pulling the engine, it looked like most of the ejection charge blew out the back, down the sides of the square bodied engine mount."

2. "I couldn't find the engine lock ring! The engine was friction fitted. Only the nose cone separated at ejection, no parachute. The engine ejected, no damage but a small melt in the parachute."

The picture above is from the first launch, Note the ejection charge lines going down and out the back -
 

kuririn

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Chris, thank for the input. I may have to glue the motor mount to the rear bulkhead to insure it doesn't leak backwards. Will see after the shakedown flight.
 

BABAR

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For my balsa helis and airbrakers I put Mylar tape on the inside areas that tend to get scorched by ejection gases and particles.

You said this was the third of 5 you’ve built (sounds like a Borg name—- again I have been watching too much Star Trek Voyager). How did the first two fly?
 

kuririn

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Just built 'em last week so they haven't maidened yet.
We'll see. Might do an Estes Death Star number on me.:D
 
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