Pemberton Low Power Kraken Build

[Skp]

I am aware I have not yet finished the Semroc Maple Seed, however it is mostly in the finishing stages. Which is as interesting as watching paint dry. Also with the fire bans we are currently enjoying there is no rush to get it done.

In the same order from ERockets, I got the Low Power Kraken. Most of the info that I have found is for The King Kraken, so I figured a build thread for the low power one would be appropriate.

The Bag
The Parts

There really is not much to the kit. I was able to check off all the parts as received and they are of good quality. However there is one part that is really baffling: the launch lug is only 1/8"
In the destructions there is a sentence on the 1st page:"Some images may vary from actual content and reality in general." The parts list does not give a measurement for the lug size, just that there is one. At step 24 it does indicate that I should be expecting a 1/4" launch lug in the kit.

I have a lot of 3/16" launch lugs in my parts box, and given that I don't foresee launching on anything larger than an F, we will go with that.

 

[Pem Tech]

I am aware I have not yet finished the Semroc Maple Seed, however it is mostly in the finishing stages. Which is as interesting as watching paint dry. Also with the fire bans we are currently enjoying there is no rush to get it done.

In the same order from ERockets, I got the Low Power Kraken. Most of the info that I have found is for The King Kraken, so I figured a build thread for the low power one would be appropriate.

View attachment 314990 The Bag
View attachment 314991 The Parts

There really is not much to the kit. I was able to check off all the parts as received and they are of good quality. However there is one part that is really baffling: the launch lug is only 1/8"
In the destructions there is a sentence on the 1st page:"Some images may vary from actual content and reality in general." The parts list does not give a measurement for the lug size, just that there is one. At step 24 it does indicate that I should be expecting a 1/4" launch lug in the kit.

I have a lot of 3/16" launch lugs in my parts box, and given that I don't foresee launching on anything larger than an F, we will go with that.

My apologies. After selling the Kraken for many years we discovered that most customers prefer a 1/8" LL for LPR rockets. So we switched to the 1/8". However, it appears we need to update Step 24 of the Destructions.
Any particular reason your chose a 3/16" LL? Just curious.

 

[Skp]

My apologies. After selling the Kraken for many years we discovered that most customers prefer a 1/8" LL for LPR rockets. So we switched to the 1/8". However, it appears we need to update Step 24 of the Destructions.
Any particular reason your chose a 3/16" LL? Just curious.

It is very good thing you put the disclaimer in that you did. I chose the 3/16 because I have plenty of them laying around. Also I have a very nice long 3/16 rod.

 

[Skp]

I won't provide much detail for cutting the fins, other than to say that the directions are clear and the results are sweet. Now that I know how to make cuts, I have visions of upscales, downscale, goonscales, 3 fin, 6 fin and who knows what madness may follow. You can make these cuts as well, go buy the kit now.

 

[Skp]

The canards are hand cut from stock using a provided template. The stock is rather thick for the overall size of the canards.

I have decided to go for an angular look with a sharp beveling of the leading and trailing edges only. It was done freehand and turned out pretty nice.

The nosecone was sanded with 320 grit paper and the canards glued on with wood glue.

 

[dhbarr]

That is one sharp squid!

 

[Banzai88]

View attachment 315162
I won't provide much detail for cutting the fins, other than to say that the directions are clear and the results are sweet. Now that I know how to make cuts, I have visions of upscales, downscale, goonscales, 3 fin, 6 fin and who knows what madness may follow. You can make these cuts as well, go buy the kit now.

Yeah, at first glance the instructions are WTF? Then once you lay it out following the pictures, it all makes sense. Go slow, sharp blade, and steady hand!

 

[Skp]

Go slow, sharp blade, and steady hand!

Amen! I did poke pin holes at the intersections of the cuts for a physical stop. Also, instead of drawing lines, I gently scored the pattern with the back side of the blade while the template was in place on the tube. Using the sharp side of the blade would have made a quick mess of the edge of the template and the tube.

 

[Banzai88]

Amen! I did poke pin holes at the intersections of the cuts for a physical stop. Also, instead of drawing lines, I gently scored the pattern with the back side of the blade while the template was in place on the tube. Using the sharp side of the blade would have made a quick mess of the edge of the template and the tube.

I hear ya. I've done the LPR and the HPR version of this kit, both times I drew the lines, scored, then cut. Takes me about 3 full revolutions to get a full cut through with a fresh, new single edge razor blade.

 

[Nytrunner]

View attachment 315162
I won't provide much detail for cutting the fins, other than to say that the directions are clear and the results are sweet. Now that I know how to make cuts, I have visions of upscales, downscale, goonscales, 3 fin, 6 fin and who knows what madness may follow. You can make these cuts as well, go buy the kit now.

That looks nice and consistent!

goonscale?

 

[Skp]

That looks nice and consistent!

goonscale?

Thank you, slow, steady and new blade. Goonscale may be the start of the tube fin madness. Typically a Baby Bertha kit made to look like a short fat version of something else. It is already a Bt-60 model so I am not sure if I want to go fatter, but leave the fins at Bt-60s or if I want to leave the airframe a Bt-60 and drop the fins down to a Bt-55 or a Bt-50. From there the madness will grow.

 

[Coop]

Nice job'. Kraken fins can be intimidating and nerve-wracking, but the results are so, so worth it...

Later!

--Coop

 

[Skp]

If there is a part of model rocketry that you don't like, it is best to try to outsource it.

It is a fair amount to fill.

 

[Skp]

I have not yet built the Motor Mount, but the MM on this kit is the most basic one you could imagine. Motor mount tube and centering rings.

For motor retention, use tape according to the destructions.

Due to it's simplicity, I have had to come up with something much more complicated and experimental.

I have not seen a motor mount built this way, so if anyone has done it and has any insight into it's effectiveness, please comment.
I got the idea from the Mega Vortico. Where you can tape a thrust ring AND an ejection ring on the motor to hold it in place.
The centering rings will be glued to the inside of the rocket airframe, with notches cut out of them and stops glued to them.
The motor mount tube will have 2 runners on opposite sides with gaps to lock onto the rings.
The mark on the motor mount is where I will be shortening it so that even an Estes D motor sticks out both sides.


I have seen, but never built, motor mounts with the centering rings glued to the motor mount tube and the locking mechanism on the airframe tube. For example look up the Semroc SLS Hustler. It uses through the wall fin tabs with gaps to lock onto the forward centering ring.

 

[bradycros]

Looks good so far!

 

[Skp]

Here is the motor mount assembly all set to glue into the airframe.

As you can see, the tube is short enough that even a D can get a wrap of tape on the both ends.

I plan to fully assemble it and then glue just the forward centering ring into the airframe. Remove the rest of the mount to fillet the forward centering ring. Glue the aft centering ring while mounted on the motor tube, then remove the motor tube to fillet the aft centering ring.

I believe this will be very effective. I did get this built prior to Jim/Blackjack2564 showing how to accomplish the very same thing, in another thread, with a short MM by placing the ring of tape on the forward end of the motor, then inserting the motor from the front of the rocket, then taping/or assembling the aft ring of the motor.

 

[Coop]

I'm not sure I understand the need for this. Why the extra work and hassle installing the motor in such a manner? Especially on a 1.6"/24mm --I've had a few Estes D's I've had to sand down to fit in 24mm MMTs as it is. I can only imagine the frustration at the field trying to slide it in backwards.

Have you done this before?


Later!

--Coop

 

[Skp]

I fully assembled the motor mount with both centering rings, put a ring of Tight Bond No Drip glue near the location of the front centering ring, and inserted the mount so that the motor mount tube was flush with the rear of the airframe.
I did go a little light on the amount of glue. I did not want it getting on the motor mount tube, and gluing that to the airframe.
After letting the glue set, I removed the motor mount assembly, and filleted the front centering ring.
After the fillet was dry, I put thin CA on the front centering ring and just the front of the motor mount. I then sanded the centering ring and the locking rails so that the mount would easily pass through the centering ring and twist to lock.
I repeated the process with the rear centering ring. It was important that I made the motor mount tube flush with the rear of the airframe, because I just wanted to push the rear ring into place without having to guess at the proper depth to mate with the front centering ring.
Then I thin CAed the whole motor mount and rear centering ring. A little more sanding and fiddling to make everything move easily.
And the removable motor mount is done. It feels very sturdy and smooth without being sloppy or wiggly,
I am very optimistic that this will hold up and stand the test of time.

 

[Skp]

I'm not sure I understand the need for this. Why the extra work and hassle installing the motor in such a manner? Especially on a 1.6"/24mm --I've had a few Estes D's I've had to sand down to fit in 24mm MMTs as it is. I can only imagine the frustration at the field trying to slide it in backwards.

Have you done this before?


Later!

--Coop

I have used friction fit with single use Estes motors with nearly 100% success. I don't have much experience with reloads at all. I am building this with the expectation of primarily flying with reloads and am a little nervous about spitting a case. I also had a hard time picturing holding the airframe around the tube fins and struggling with a stuck motor. I have never built a motor mount like this before, but have played with the idea for a while. This seemed the right opportunity.
So far the mechanism seems to operate smoothly and easily, so I am looking forward to trying it out.

As a word of warning, most of my mods to kits have not improved upon the original design.

 

[T-Rex]

I have used friction fit with single use Estes motors with nearly 100% success. I don't have much experience with reloads at all. I am building this with the expectation of primarily flying with reloads and am a little nervous about spitting a case. I also had a hard time picturing holding the airframe around the tube fins and struggling with a stuck motor. I have never built a motor mount like this before, but have played with the idea for a while. This seemed the right opportunity.
So far the mechanism seems to operate smoothly and easily, so I am looking forward to trying it out.

As a word of warning, most of my mods to kits have not improved upon the original design.

I have had in my head a similar design, but solely for the purpose of changing out the MMT for different sizes or clusters....

 

[Pem Tech]

Here is the motor mount assembly all set to glue into the airframe.
View attachment 316206 View attachment 316207 View attachment 316208
As you can see, the tube is short enough that even a D can get a wrap of tape on the both ends.

I plan to fully assemble it and then glue just the forward centering ring into the airframe. Remove the rest of the mount to fillet the forward centering ring. Glue the aft centering ring while mounted on the motor tube, then remove the motor tube to fillet the aft centering ring.

I believe this will be very effective. I did get this built prior to Jim/Blackjack2564 showing how to accomplish the very same thing, in another thread, with a short MM by placing the ring of tape on the forward end of the motor, then inserting the motor from the front of the rocket, then taping/or assembling the aft ring of the motor.

Interesting....

 

[Pem Tech]

I fully assembled the motor mount with both centering rings, put a ring of Tight Bond No Drip glue near the location of the front centering ring, and inserted the mount so that the motor mount tube was flush with the rear of the airframe.
View attachment 316300 I did go a little light on the amount of glue. I did not want it getting on the motor mount tube, and gluing that to the airframe.
View attachment 316301 After letting the glue set, I removed the motor mount assembly, and filleted the front centering ring.
After the fillet was dry, I put thin CA on the front centering ring and just the front of the motor mount. I then sanded the centering ring and the locking rails so that the mount would easily pass through the centering ring and twist to lock.
View attachment 316302 I repeated the process with the rear centering ring. It was important that I made the motor mount tube flush with the rear of the airframe, because I just wanted to push the rear ring into place without having to guess at the proper depth to mate with the front centering ring.
Then I thin CAed the whole motor mount and rear centering ring. A little more sanding and fiddling to make everything move easily.
View attachment 316303 And the removable motor mount is done. It feels very sturdy and smooth without being sloppy or wiggly,
I am very optimistic that this will hold up and stand the test of time.

HOLY GEEZZZ! That is cool, and complicated.

 

[Pem Tech]

Dupe.......................

 

[Pem Tech]

The canards are hand cut from stock using a provided template. The stock is rather thick for the overall size of the canards.
View attachment 315163
I have decided to go for an angular look with a sharp beveling of the leading and trailing edges only. It was done freehand and turned out pretty nice.
View attachment 315164
The nosecone was sanded with 320 grit paper and the canards glued on with wood glue.
View attachment 315165

Pretty nice?
They turned out gorgeous!
Much admiration........

 

[Skp]

Thank you Layne,

The kit comes with a washer for nose weight.

However the nose cone is cleanly drilled to a depth of almost 4 inches.
So rather than use the washer, I am using clay and some pinewood derby composite weights to match the washer weight and fill the nose cone cavity.

It moves the CG ever so slightly farther forward, which cannot be a bad thing.

cavity filled and screw eye attached

thin CAed and ready for primer.

 

[Skp]

Spirals filled: Check
Glue lines Masked off: Check
Edges sealed with thin CA: Check
Nose cone sealed with thin CA: Check
Primer ready.

1st coat of prime and still much to be done.

 

[Daddyisabar]

Great build and good, museum quality technique!

 

[Skp]

Great build and good, museum quality technique!

You have no idea how badly I want a flawless finish on this sexy beast.:drool:

 

[Daddyisabar]

You have no idea how badly I want a flawless finish on this sexy beast.:drool:

I will bring my magnifying glass and rivet counting scale attitude when you bring it to the launch for intense judgement!

 

[Coop]

You have no idea how badly I want a flawless finish on this sexy beast.:drool:

Yes.... yes I do. I've built a few of these. Heheh. That's the thing about them. They breed. Next thing you know, you're calculating upscales....


Later!

--Coop