How many times can you restore a rocket? At least 3!

[mooffle]

Restore thread but also discussion on what is too much to restore vs throw away and start over from scratch

If you have a keen eye maybe you can tell what this started life out as, I won't spoil it other than to say it was a kit. It has been restored once as the rocket seen below. My son helped me paint it as the Prism so after the last launch hit the ground hard I gave him two choices:
-Pull the chute and maybe the engine mount and hang or display it in the space section of his room or
-Fly it until it has zero life
He said fly it, buuuut... that hard landing crunched the front end of the tube and after trimming it back about an inch it's very marginally stable. There was already about 20g of nose mass added and frankly, I don't want to add more.

The biggest idea I'm playing with is to remove the nose weight totally, add a 10-15 cm payload bay to move the CP, then fill the bay with some sort of LED blinker for night launching. A multicolored system would fit the theme of the rocket well and I've been trying to get away from nose weight if I have a chance to make it functional somehow, so this appeals most.
Another idea is to add some sort of stick fins to the existing fin grouping, however I like the current asthetic and cant decide how to go about this.

Thouights, discussion, tangentially related ideas are all apreciated here.

 

[PayLoad]

A LONG time ago, this started as a PML Bull Puppy. As long as I can glue it back together, she is my go-to.

 

[Bill S]

I'd just use a coupler to add a few inches to the front and call it done. Assuming it doesn't interfere with parachute, etc.

 

[teepot]

I'll fix one as many times as I can as long as the fin can survives and there is enough body tube left to add a coupler.

 

[mooffle]

I'd just use a coupler to add a few inches to the front and call it done. Assuming it doesn't interfere with parachute, etc.

That feels too easy haha. After lunch I am going to start on a payload bay for sure though.
We've been playing around with an electronics kit that does your basic flashlight and buzzer stuff and I found some tiny 3v solar cells that I'd love to incorporate into a rocket. Pictures to come soon.

 

[caveduck]

We are rocket surgeons - there is no limit to restoration!

 

[mooffle]

Apparently my post didn't go through.
Bulkhead is carved and sanded. I used a full tube to test fit to be sure it is straight and do the 'pool cue roll test'. Once I figure out stability and payload margins then I'll cut it.

 

[Tractionengines]

That coupler looks short. You want at least 1 caliber in each body tube.
(Maybe just photo angle...)

 

[mooffle]

That coupler looks short. You want at least 1 caliber in each body tube.
(Maybe just photo angle...)

I've never heard that rule of thumb. It's a little over half, think it'll be ok? I was going to glue the front tube in place and keep the parachute in the middle.

 

[Tractionengines]

Estes sells some kits with very short couplers, so its not a hard rule, but does help with stability especially while under thrust, to have more engagement with the tube.
What do other's think? I would like to see longer. But that's my opinion and YMMV.

 

[mooffle]

Two major problems came up last night.

The first that as I was trying to remove the clay nose weight the eyelet was barely holding on and came off and when I bored the hole in the rear cone on the NC the plastic split. I had to take it back to the shoulder. So, no payload bay now but thats ok because the nose itself will hold the payload. @Tractionengines your concern about 1 caliber shouldn't be an issue now as about half the coupler will go in the base of the nose. It sorted itself out

The second is that as I was trying to mess with masses and payload tubes in OR the only way the rocket would be stable for any range of engines was to add 20g! of nose mass as far forward as possible. I liked the asthetic that was going on but even with small batteries and LEDs I was hitting about 8g. More fin area it is and this rocket really never had enough anyway.

 

[Back_at_it]

I have built / restored the same rocket 5 times. I built my original Photon Disruptor back when I was a kid and flew that thing so many times I lost count. After about 5 years It had all of the fins broken off at various times and the top of the tube was very badly dented and had been shortened a couple of times so I restored it back to new then flew it for a few more years until it unfortunately had a parachute tear away and came down hard. It was rebuilt a few months later and returned to service where it promptly got caught in a tree. We bent it pretty badly getting it down so once again it was set aside and eventually rebuilt and flown until I left the hobby.

About 3 years ago when I returned to the hobby, I pulled it from the pile and gave it a complete restoration complete with a set of decals sourced from eBay. This time it was rebuilt with 24mm power.

The funny thing is that the nose cone and four of the six fins are original. They were cut from the body tubes, sanded and reused.

 

[Back_at_it]

Estes sells some kits with very short couplers, so its not a hard rule, but does help with stability especially while under thrust, to have more engagement with the tube.
What do other's think? I would like to see longer. But that's my opinion and YMMV.

Agreed. I use at least 4 inch on everything up to BT55 and use 6 inch above that.

 

[mooffle]

My mind sim is buggy on this project. Added that ring fin and it's still unstable on a C and B

 

[Tractionengines]

That ring fin is a LOT of area. I would guess if it was marginal before, it should be good now. If it takes more than that, it was really close to unstable before... open rocket support for tube-fins / ring fins is limited. (The new version should be better, but it's not released yet.)

 

[mooffle]

That ring fin is a LOT of area. I would guess if it was marginal before, it should be good now. If it takes more than that, it was really close to unstable before... open rocket support for tube-fins / ring fins is limited. (The new version should be better, but it's not released yet.)

It was definitely marginal before and it had a LOT of nose weight, around 25 grams if I have to guess. I didn't measure it.

I'm not exactly happy with the look but maybe once it is matched black with rainbow scribbles it'll look good. I just can't picture it right now

 

[Back_at_it]

It was definitely marginal before and it had a LOT of nose weight, around 25 grams if I have to guess. I didn't measure it.

I'm not exactly happy with the look but maybe once it is matched black with rainbow scribbles it'll look good. I just can't picture it right now

I built a rocket very much like this some years back but without the extra fins outside the ring. It was a BT60 main tube about 14 inched long. The outer ring was a BT101 that was two inches long. At the time I did not have OR so my buddy built the SIM. We couldn't get it to be stable in OR without increasing the fin surface.

In my mind I knew that it had way more fin than needed so we left the design alone and string tested it which showed good stability. First flight was done without anyone around. It was a good but not great flight. It wobbled slightly on launch but nothing serious. I added about 1/2oz of nose weight and launched it again an hour later and got a perfect flight.

I don't think OR handles Ring fins correctly and it was telling us to increase the fin surface when it really needed nose weight.

 

[mooffle]

I don't think OR handles Ring fins correctly and it was telling us to increase the fin surface when it really needed nose weight.

It might be time to revisit OR, I didn't think 15.03 had a ring fin option, I've done it a few times now and had to fudge it. I looked and didn't see an option? is there a reasonable way to sim it?

On that note this build is really going to make me consider a RockSim purchase soon. It's hard to say anything bad about OR especially for being free and open source (kudos to the devs, I know you guys work hard) but many of my designs go past 3FNC and it definitely shows its limitations.
My original .ork wasn't giving me good data until I put the double fin as a single unit. I think RS does this better

 

[mooffle]

Here it is with a matching coat of black. time to hit it with some paint markers!

 

[mooffle]

I fully intend to update this thread but so far my son hasn't been in a painting mood so it might be a while...
Also delayed so I can study up on some basic electrical theory, I really want to turn this into a night flyer with some sort of light up thing.

 

[mooffle]

Space is a 12cm estes ogive PNC55 for reference.

 

[teepot]

You can use clear plastic tubes from Apogee to put lights in. I've done that on two rockets. I used small lights that runners use and lights for bicycles.

 

[nosecone]

I restored my Saturn V 3 times.

 

[mooffle]

Fully finished!
Only a little touch of paint marker added to the fin tube along with 3 LEDs mounted in the nose. Unfortunately the payload doesn't do anything more than light up but I had more fun building that portion than i expected. That just means more electronics in the future on my workbench.

 

[mooffle]

Here's a few detail shots from the work yesterday, sorry there aren't more 'in progress', it happened quick and I wanted to concentrate on the build vs documentation.

However some notes on the process:
The battery pack was from a broken spinning heli toy which is why it has that odd shaft. It worked well to my advantage here and CA+lots of surface area makes a good hold.
Pilot holes were a must for those 5mm LEDs, and in picture 3 I realized that Estes noses have ridges at 90 and 60 degree separations. I wish I had known that years ago.
Thick CA holds all 3 LEDs and the switch in place. The LEDs are only about halfway out, they don't seem as long as they are until they poke through (~7mm). Due to the freehand soldering the spacing took some effort to get placement right as well.
Apparently red LEDs have lower resistance or at least mine does, you can maybe see the resistor in there on the positive red lead. Without that in place the blue and green would almost not light despite being in parallel.