My Sumo 'Quickie" build

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jlnel

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Well, had a great time at a local ( LOL--LOCAL ) rocketry club last night. My workplace was pretty much closed today so I thought it was a fine time to start my Sumo build. Since Saturday is the next launch, I am trying to get this built so I can do a L1 attempt. No pics - never happened... well I made sure to take pics!

a.JPG
The box!!

b.jpg
I played with some of it before taking pic.

c.JPG
This is kinda how im doing the motor mount. I will not be doing the piston system so I used that piece to strengthen the tail section. The piece that would be the bottom of the piston I drilled out and will use it as a fourth CR and a mount for the recovery harness.

d.JPG
All the mmt parts laid out. I trimmed a bit of off the piston to make the front CR/Mount as seen to the left.

e.JPG
I added rail buttons. epoxied the back and kept the launch lugs on other side, shown in next pic. I guess I have no idea of what launch system ill be using!

f.JPG
Launch lugs too.

g.jpg
A shot of it w/ nose cone. I gave it a light sanding to start smoothing out the plastic. MMT is installed but the forward still need to be installed. I left it till the end so I could get to epoxy the inner CR.

h.jpg
The rear of the MMT is done. I JB Welded the Aerotech retainer in place... I need a motor for Saturday!!!! Can anyone can help out? 29mm, is there a vendor that will be there, I did read that one shows up but are they a regular attendee?


That's it for now. I will finish the front CR/Harness mount and maybe fill the body tube spirals tonight, but im tired.

Tomorrow I hope to get fins on, get the epoxy fillets done, get the recovery system laid out and prep body for primer... not sure if it will be painted for sat.
 
Well, I got the recovery system done and nose cone attached. got the fins tacked on too. ill let everything dry overnight and fill spirals and get fillets done Thursday I hope.

i.jpg
j.jpg
k.jpg
l.JPG

another late night...JLNEL out!! ZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
 
jlnel said:
Well, I got the recovery system done and nose cone attached. got the fins tacked on too. ill let everything dry overnight and fill spirals and get fillets done Thursday I hope.

View attachment 149667

another late night...JLNEL out!! ZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
Click to expand...

I wouldn't attach your recovery harness to the molded nose cone loop. They break off with alarming regularity.
 
You can mount a screw-eye into the nose cone and use that to secure the shock cord to. You can cut a little opening to get the nut through and epoxy it.
IMG_Argent__100.jpg
 
On all my larger rockets I have been using the method dward posted. Definitely do not use the molded loop on anything over 24MM engines, too risky.

Nice build :)
 
I had a D ring sitting around...
cone.JPG

does it look ok? I am going to epoxy over the nuts..:y:
the two opening I made, do you guys think I can leave as is?
 
You can leave them open as is, or as long as you use the epoxy on the back so it deosnt come loose you can glue the pieces back on. Personal preference there.
 
dgreger said:
You can leave them open as is, or as long as you use the epoxy on the back so it deosnt come loose you can glue the pieces back on. Personal preference there.
Click to expand...

LOL, no pieces left!! I tried to do a smaller hole.. fingers didn't fit... bigger hole... still fingers didn't fit, then these. I epoxied the nuts on the back, there is a backing plate under the nuts that ties them together, seems very strong.
 
I think just using a quick link would have been fine or just making a loop in the shock cord about two feet from the nose cone. Nothing is going to break off on your nose cone. Why over think or over build? I never listen to anyone on here. You just made more work for yourself IMO

I can't wait for everyone to jump on my comments, but hey it's true.
 
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Also all you are doing is adding a bunch of weight you don't need and you butchered up a completely good nose cone. It looks terrible. Your quick build turned into a big project because everyone thinks rockets need to look like and weigh like tanks!!!
 
dward said:
You can mount a screw-eye into the nose cone and use that to secure the shock cord to. You can cut a little opening to get the nut through and epoxy it.
View attachment 149676
Click to expand...

That's a good idea, but I think the size is over kill.

Why not just tie a slip knot with Kevlar? Use some wood glue on the knot and your done with it. Or another option is use a properly sized quick link with either a Kevlar loop or nylon shock cord. God forbid we use elastic. It's not like the ejection charges are gonna burn through it. Keep an extra in the field box just in case the cord looks like it's getting frayed.
 
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How much does this SUMO really weigh? Put that in perspective. The lighter it is the better it will fly and if it goes ballistic (not that any ballistic rocket is safe) at least there won't be that much weight.
 
Under ideal conditions, i.e. deployment at apogee, you probably won't have any trouble with the plastic tab. However, you don't always have ideal conditions and the better safe than sorry approach pays off. The extra nose weight can only help static stability and unless you are set up for dual deploy, I would want my L1 flight to not fly very high, because if it drifts miles away and you can't find it, then you don't get your certification, and you're out a rocket. With that said, I understand the overbuild argument. There are ways to protect that tab from breaking without a screw-eye: really long shock cord or attaching the kevlar to a loop of elastic material (tubular nylon or the rubber bands on smaller rockets). Kevlar is really good at slicing through polystryrene like butter. Come to think of it, I didn't notice if you said you were using kevlar or tubular nylon. If the latter, you probably would have been ok. It's an aerotech rocket, so it is probably tubular nylon. Should have caught that.
 
dward said:
Under ideal conditions, i.e. deployment at apogee, you probably won't have any trouble with the plastic tab. However, you don't always have ideal conditions and the better safe than sorry approach pays off. The extra nose weight can only help static stability and unless you are set up for dual deploy, I would want my L1 flight to not fly very high, because if it drifts miles away and you can't find it, then you don't get your certification, and you're out a rocket. With that said, I understand the overbuild argument. There are ways to protect that tab from breaking without a screw-eye: really long shock cord or attaching the kevlar to a loop of elastic material (tubular nylon or the rubber bands on smaller rockets). Kevlar is really good at slicing through polystryrene like butter. Come to think of it, I didn't notice if you said you were using kevlar or tubular nylon. If the latter, you probably would have been ok. It's an aerotech rocket, so it is probably tubular nylon. Should have caught that.
Click to expand...

Excellent and valid points! As far as shock cords I think a combination of two types of materials works well either nylon and Kevlar or elastic and Kelvar. Just to absorb some shock in case there is a late deployment. If you really wanted to you could take about 18" of the elastic cord and attach that to the end of the shroud lines on the chute. That would also allow it to "give" I think static cords are find if they are long enough and if you have a good deployment at Apogee or very close to it.

I think if this was a large 5-8" diameter rocket and weighed above 40lbs yes I could definitely see suggesting "some" of the build techniques in this thread, but it's a short fatty, which in it self is pretty cool and really doesn't come in at more than maybe 35-40 oz or around 3 lbs. So some moderate upgrades are nice, but I think finding the correct balance of weight and strength is more important than over building.
 
I never listen to anyone on here. You just made more work for yourself IMO

...you butchered up a completely good nose cone. It looks terrible.

Too much negativity and criticism there Afterburners. Why post and be a member here if you don't listen to anyone and criticize everything? Just seemed to be a bit harsh is all ... This place is for sharing ideas and learning ... not bashing ideas and being closed minded.

I can't wait for everyone to jump on my comments, but hey it's true.

Ok I jumped ... and no it't not true, its your opinion. Happy flying ...
 
jlnel said:
I had a D ring sitting around...
View attachment 149684

does it look ok? I am going to epoxy over the nuts..:y:
the two opening I made, do you guys think I can leave as is?
Click to expand...

I think you did a great job ... especially if it is you first NC mod. Considering the size and weight of this kit when finished and loaded the tiny bit of added weight will make little to no difference in flight performance. When I have made similar mods to my NC's I just put some masking tape over the holes. You generally have to add some to the shoulder of the NC anyway to get the right amount of friction.

Good luck with the build :)
 
Thanks for the compliment on the nose cone. yes it is my first time modding one, i'm sure not the last!! I asked for input so if afterburner came across badly that was his thoughts. i'm sure there is no one way that everyone will agree on and i'm happy how this nose cone turned out, for now. I do think it looks a bit rough and may cut off shoulder and do a bulkhead?? I don't want people bashing each other but rather just show.. " this is how I would have done it" type of posts, that way everyone can learn something possibly.

I plan on building MANY rockets over the next few months and hope to continue to have great input from everyone, i'm thinking a "poll" rocket build.... building something from voting results! lol that sounds dicey :wink:
 
SacEsq said:
I never listen to anyone on here. You just made more work for yourself IMO

...you butchered up a completely good nose cone. It looks terrible.

Too much negativity and criticism there Afterburners. Why post and be a member here if you don't listen to anyone and criticize everything? Just seemed to be a bit harsh is all ... This place is for sharing ideas and learning ... not bashing ideas and being closed minded.

I can't wait for everyone to jump on my comments, but hey it's true.

Ok I jumped ... and no it't not true, its your opinion. Happy flying ...
Click to expand...

Don't get your panties in a twist. It's true the nose cone looks terrible and was poorly done. I'm not being negative. I'm being honest. Am I suppose to tell the guy he did an excellent job. I wouldn't want that as nose cone. There are other options. It's not his fault it turned out the way it did. If he would have listened to someone who knows what they are doing...he wouldn't have had this problem. I'd cut off a portion of the shoulder and put a bulk head on it to clean it up. Why offer someone bad advice which is exactly what some of you guys are doing. Asking the OP to build a tank when it's not necessary is bad advice. It makes the rocket too heavy and if it comes in ballistic it would probably kill someone for sure or go through someone car roof. Just because you guys think you need 4 lbs of epoxy for fillets or need another 5-10 lbs in hardware or 40 coats of paint... to fly what was a lite weight rocket, which is pretty much what the SUMO is in comparison to what you guys build. Now this rocket is tank. Like I said and it's worth repeating. Finding the proper balance between weight and strength when upgrading a kit is the key to building. You have to ask yourself and be honest if putting all that hardware on a rocket is necessary. My suggestions are sound and make sense. Lite weight which translate into a great flying rocket...

Yes you're right it is my opinion, but in this particular case it also happens to be very true!!

You guys keep trying to reinvent the wheel.:facepalm:

I have a SUMO too in the box. I'll do a build thread and kindly share with you how it should be done.
 
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Well I guess you are right and know everything. Everyone else is wrong and should have kept their mouths shut since it was such terrible advice.
 
I generally have not had an issue with the plastic ring. I don't attach the chute there however. I attach it on a loop made a bit down on the shock cord. Of course there are those that would tell you the knot is now the weak point! But what you did should work as long as there is enough meat left on the nose cone.
 
Wow dude ... who's panties in a bunch? Was just trying to point out the difference between offering friendly constructive advice and being arrogant and rude. No need to take your ball and go home.

Happy flying.
 
jlnel said:
I had a D ring sitting around...
View attachment 149684

does it look ok? I am going to epoxy over the nuts..:y:
the two opening I made, do you guys think I can leave as is?
Click to expand...

I have done something like this before. What you are doing is internal and will never be seen on the launch pad. Your choice to reinforce the attach point was the right one, that's what matters most. Style points can be worried about when you get to future builds.
 

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