Semroc Sprite

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JAL3

JAL3

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One of the events for my first competition on re-entering rocketry is an "Upscale" Competition. I am entering a Hawks Hobby Super Sprite for that one and figured I would build the Semroc version of the original for comparison.

package-1.jpg
 
Funny, I just built one a couple days ago - interesting little bird. Do you know if the original was weird like the Semroc clone? I never had an original. Not weird in a bad way, more a unique way.
 
One thing I quickly noticed is that Semroc has made a change in their way of doing things, at least with this rocket. All of the Semroc kits I built before used rings printed on the instructions to mark the lines on the BT. This kit had a wrap-around template. I know its a matter of personal preference but I am grateful to Semroc for this change.

template-1.jpg
 
chadrog said:
Funny, I just built one a couple days ago - interesting little bird. Do you know if the original was weird like the Semroc clone? I never had an original. Not weird in a bad way, more a unique way.
Click to expand...
Weird, how? What 'cha mean?
 
chadrog said:
Funny, I just built one a couple days ago - interesting little bird. Do you know if the original was weird like the Semroc clone? I never had an original. Not weird in a bad way, more a unique way.
Click to expand...

What do you mean by "weird"? It was definitely different in that it used tumble recovery, was a ring fin and used some "early" methods of construction. I believe it originated not as a kit but as an MRN plan.
 
Oops.

Lost track of time and have to head to the hospital.
 
Weird in the way that it uses a mini engine in the heavy tube that shifts rearward then vents through the side of the tube. There were no mini engines then as we know them today, right? Just seems like this Semroc version is more advanced than it might have been back then.
 
chadrog said:
Weird in the way that it uses a mini engine in the heavy tube that shifts rearward then vents through the side of the tube. There were no mini engines then as we know them today, right? Just seems like this Semroc version is more advanced than it might have been back then.
Click to expand...

I've got just a moment before starting rounds.

I believe the original Sprite used the "shorty" motor which was a shortened version of the 18mm casing. For Semroc to adapt it to use 13mm, and maintain the size, they had to have an adapter. They also needed to make up the mass balance so that it would "tumble". As I recall, tumblers are very sensitive to the amount of weight that is shifted.

Others who know their rocket history better than me are invited to chime in.
 
chadrog said:
Weird in the way that it uses a mini engine in the heavy tube that shifts rearward then vents through the side of the tube. There were no mini engines then as we know them today, right? Just seems like this Semroc version is more advanced than it might have been back then.
Click to expand...

That sounds like an Estes Scout (I think?) from the 70's. It used an 18mm motor (I think?) that shifted and vented, to change it to tumble recovery. I remember it had an extra long motor hook (I think?).
 
Are the "adapter" casings reusable? I looked at the instructions and it mentions gluing in the mini engine. That does not sound good for multiple launches.
 
Spacepirate R said:
Are the "adapter" casings reusable? I looked at the instructions and it mentions gluing in the mini engine. That does not sound good for multiple launches.
Click to expand...

I see no reason that friction wouldn't work, but they do include four adapters with the kit - I'm sure mine will be lost before they're used up.
 
Your just a building away here lately John. It's good to see you back at it full on.

We missed you at the open. Art did his best to give me a hard time but it's just not the same as when you do it.:p
 
I am looking at one of my original Estes Sprite models and it comes with a Bt30 white parallel wrapped tube. I can't remember but I also thought Estes used brown Bt30s for the sprite. I think Semroc is using a slightly smaller tube for a better motor fit. The wrap around marking guide that Semroc has in their kit is the same one that is used in the Estes Sprite kit. The original Sprite also comes with Gauze to reinforce the motor hook. The instructions also specify to use the "Series III motors because of the weight distribution and the use of any other motor may not work" The original Shorty motors weighed .39-.47oz. The new mini motors only weigh .2-.28oz so with the mini adapter that may bring the weight of the motor up to specs. Also the old kit came with balsa wood and you had to cut the fins out.
 
SCIGS30 said:
I am looking at one of my original Estes Sprite models and it comes with a Bt30 white parallel wrapped tube. I can't remember but I also thought Estes used brown Bt30s for the sprite. I think Semroc is using a slightly smaller tube for a better motor fit. The wrap around marking guide that Semroc has in their kit is the same one that is used in the Estes Sprite kit. The original Sprite also comes with Gauze to reinforce the motor hook. The instructions also specify to use the "Series III motors because of the weight distribution and the use of any other motor may not work" The original Shorty motors weighed .39-.47oz. The new mini motors only weigh .2-.28oz so with the mini adapter that may bring the weight of the motor up to specs. Also the old kit came with balsa wood and you had to cut the fins out.
Click to expand...

The Semroc version is state of the art, it comes with tyvek instead of gauze. It must have been a bear to cut those fins.
 
Spacepirate R said:
Are the "adapter" casings reusable? I looked at the instructions and it mentions gluing in the mini engine. That does not sound good for multiple launches.
Click to expand...
From the instruction sheet: "Glue or wedge-fit a small “T” type engine (mini-engine) in the empty casing so it is even with both ends of the casing."

I haven't started mine yet, but I'm looking forward to it—also looking forward to seeing yours. It's one of those early rockets that I consider a classic. It will be interesting to see all the different paint schemes as more folks build them.
 
Semroc does a great job of updating vintage kits and yet keeping them as close to the original as possible. I will build one of my original Sprites and would like to paint like the one Vern Estes has displayed at his house.

SD801033.jpg
 
I have two of these kit and this one has a white tube and the other has a brown tube. As you can see from the package this one came with a motor adapter and another engine hook. The funy thing is there is no directions inside that discuss how to use the adapter.

DSC_0790.jpg
 
The only problem I have had with my Semroc “Sprint” is that I can’t keep the motor, along with its adaptor, from blowing right past the clip that is supposed to stop it. Bending it more towards the center line doesn’t appear to help any.

The original kit, or some kit that used this system, had a heavy gauge round rod that projected far more into the path of the motor casing.

I am currently looking into modifying my “Sprint” with a more robust motor stop.
 
boomtube said:
The only problem I have had with my Semroc “Sprint” is that I can’t keep the motor, along with its adaptor, from blowing right past the clip that is supposed to stop it. Bending it more towards the center line doesn't appear to help any.

The original kit, or some kit that used this system, had a heavy gauge round rod that projected far more into the path of the motor casing.

I am currently looking into modifying my “Sprint” with a more robust motor stop.
Click to expand...

You can look at the picture of my original Sprite and see that Estes updated the kits contents to accept the newer mini motors. They added the adapter and a small EH holder for the mini motor. They kept the original longer hook to stop the adapter. I hope this helps.
 
foamy said:
From the instruction sheet: "Glue or wedge-fit a small “T” type engine (mini-engine) in the empty casing so it is even with both ends of the casing."
Click to expand...
For what it's worth, here's some more info on doing such an adaptor. This write-up shows making one from a standard length case (70mm long). The key in this application is making sure the adaptor's girth does not get so big as to make it a tight fit in the rocket. So the hook and wrap are both mounted below the outer surface in excavated areas.

Also, this write-up shows the original Estes EM-20T adaptor, whose length is correct for the Sprite application. In this case, they bury the hook as before. HTH.

Doug

.
 
The template was cut out with scissors. The instructions said to use a sharp pencil to make holes, indicated by dots, in the template to mark for the fins. My mechanical pencil would not cooperate. I used a 1/32" drill bit to make the holes. A slit was then cut in the template for the engine hook.

template-2.jpg
 
The template was wrapped around the BT, aligning the hole for the ejection charge with the extant hole in the supplied BT. The template was then secured with tape.

template-3.jpg
 
A mechanical pencil was then used to mark the endpoints for the fins and launch lug and mark the place for the engine hook.

template-4.jpg
 
The template was then removed and an Estes angle was used to lengthen the lines.

BT-1.jpg
 
A slot was cut for the hook and the hook was inserted.

mm-1.jpg
 
A film of glue was then laid down on either side of the hook and a provided piece of Tyvek was laid over it.

mm-2.jpg
 
Each of the three fins came in two laser cut pieces that needed to be removed from the stock material.

fins-1.jpg
 
The balsa sheet was lightly sanded and a razor knife was used to finish extracting the fins.

fins-2.jpg
 
The edges of the fins were lightly sanded to remove the connection points and then the first fin was placed with a double glue joint.

fins-3.jpg
 

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