So after all that... as we all know, the LJ-I has one recommended engine, the C6-3. I don't have an openrocket file for this one yet, but it seems to me a B6-2 OUGHT to be usable here for a great low altitude flight... anyone have an op on this?
Estes Little Joe I Construction - I like the kit but I have to whine a bit...
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Scott_650
Well-Known Member
Might be a little too draggy to accelerate well enough for a successful flight - but why not give it a try? The Mercury LJ should be light enough that even if the chute opens fairly low it won’t suffer much damage - other than the escape tower, which is probably going to need repaired anyway
Good time to break open a pack of new C5-3s...
Actually, on their website, Estes recommends B4-4, B6-4, C6-3, C6-5. Where did you see that C6-3 is the only recommended motor?
Could've sworn it was on the package card... Maybe I'm imagining...
Of course if I actually read the package... I would've SEEN that it said B6-2, C6-3.
I've just ordered one of these along with a Tazz Gyroc as a couple of interesting build projects for evening entertainment. Perhaps a big challenge for a rookie like me but I love a challenge! I'll post some pics when I start.
Definitely read through @hcmbanjo's build first!
Is that the same size as the Merc-Redstone (ST-20)? I made a "flying" NC/capsule so you don't have to crash your pretty "display" capsule. Highly recommended
https://www.thingiverse.com/thing:3193792
This was also a problem with gluing the angled tubes to the Expedition body. I used TBII which curled the ends. Perhaps using CA woulda worked better but could react with the paint. I fixed the curled cardboard with wood filler and sandpaper. Seems to fly straight...
Good bunch of launches! Might I suggest a clothespin to support the rocket above the blast deflector?
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I used epoxy (either 30-min BSI or West System, I forgot) on my pre-painted Expedition body tubes, and it worked perfectly.
Not only could you move the pieces a bit, to position the parts perfectly, but the cured epoxy hardened the entire structure. What was flimsy before gluing, became rock solid after attached to the body.
I think I did the same thing with the LJ-I fins as well.
I would not use CA.
It's cures brittle, and the large area of external tube's perimeter will require long application time... by which point the section, wherever you had started applying CA, will have already hardened before you get ready to finally glue things together.
Also, unlike Epoxy, you can't smooth out the inevitable CA glue bubbles that squirt out when you press two pieces together.
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I always used a spent D engine.....no squeezing of clothespin required. The main reason for using a clothes pin or engine casing is to make it easier on yourself to hook up igniters and avoid clips shorting out on blast deflector.
Don’t forget burning holes in your launch plate if the engine is siting ontop.
Have you ever burnt a hole. It warps but after maybe 50 flights..no hole. I have at least 4 plates from the cheap starter sets I brought at Walmart. Too bad your not on ease coast, gladly mail you one.
Also if worried mid and high power guys uses an electrical box cover plate.....or as a poster stated elsewhere..old pot lids, clay pot bottoms etc.
I did that once. I replaced it with a 8" diameter 1/8" thick stainles disk that I bought on eBay for $10. Stainless can take pretty high temps, ask Elon Musk.
Nearly. Many dimples. Now I use small clothespins. There was a photo posted on Facebook with a 1/4” hole. The old pot lid suggestion sounds interesting.
I recently forgot the plate and used an aluminum can with interesting results at 3:30.
hcmbanjo
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Thanks Neil,
Here's a link to the build from finish back to start:
https://modelrocketbuilding.blogspot.com/search/label/E Little Joe II
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OC-Patrick
Well-Known Member
Scott_650
Well-Known Member
Snug but it looks workable - thanks for the pix, I had a tough time visualizing the retainer fitting inside all those nozzles.
OC-Patrick
Well-Known Member
Yes it will be tight. Insert a motor to determine how far back the engine block needs to be glued. The retainer screw should be able to be turned a couple times, about 3 threads before the raised grips hit the nozzles.
Yes. I had one stick on the pad recently and it punched a very neat hole through the plate.
Nicely done!
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A little late to this party, but when I started to go active in rocketry again after a 5 year hiatus, I picked up a few kits that came out while I was on hiatus. Scale wise, I got the Little Joe 1 and the Saturn 1b.
One night recently, I did a fair amount of assembly on the LJ1. A fun build so far. Nicely engineered.
One night recently, I did a fair amount of assembly on the LJ1. A fun build so far. Nicely engineered.
Starfire73
OpenRocket Wannabe
Well, I guess I'm really late to the party. Just started my LJ1. Based on what I'm reading I think might drop the motor hook, and engine block altogether - like I did with my Booster Bertha booster. I extended the MMT just a little bit more out the back (1/4" or so) and gave it a vey thin coat of epoxy to strengthen it up. I know, it will look more obvious then the motor hook option, but no worse than a retainer.
Now, when I'm prepping to fly it I cut a 1/4" wide strip of masking tape and tape the end of the motor so the motor diameter is now big enough that it won't go forward into the MMT. Then about l wrap the motor and MMT joint with one layer of tape to keep the motor in place. It's old school, but it works great, keeps the weight down, allows me to put any 18 mm motor in it, and costs almost nothing. Finally, I use a Sharpie to write the motor code on the tape, because I'm the guy who's always double checking stuff, and when I've done this the day (or two) before, I'm still confident of which motor I taped in place.
This motor is not going anywhere until I take the tape off. It's 100% secure.
Now, when I'm prepping to fly it I cut a 1/4" wide strip of masking tape and tape the end of the motor so the motor diameter is now big enough that it won't go forward into the MMT. Then about l wrap the motor and MMT joint with one layer of tape to keep the motor in place. It's old school, but it works great, keeps the weight down, allows me to put any 18 mm motor in it, and costs almost nothing. Finally, I use a Sharpie to write the motor code on the tape, because I'm the guy who's always double checking stuff, and when I've done this the day (or two) before, I'm still confident of which motor I taped in place.
This motor is not going anywhere until I take the tape off. It's 100% secure.
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