Perfect 24" Gap Staging-- see last Post

[BABAR]

Successful C6-0 to A8-3 Ignition on minimum diameter rocket, using a BT-5 stuffer tube or "chimney" between the engines. 2 symmetrical and opposite vent holes punched in the forward end of the booster with standard paper hole punch.

"Mostly" descriptor is due to failure of separation between stages. Tried to get this launch in before work today and rushed it-- should have sanded the internal diameter of the forward end of the booster as the A8-3 was tight. A8-3 fired down the length of the stuffer/chimney with thrust out the (retained) C6-0. Successful ejection of nose and streamer from the sustainer, and the sustainer/booster came down together.

As per NAR protocol, launched solo in the field (not a soul in sight.)

They say it is better to be lucky than good, and come out with a very interesting recovery.

Booster had my "water wheel" fins, but the sustainer had standard (relative small, but standard) 3 fin config, and had the streamer and nose cone deploy.

The combined sustainer booster came down horizonal, spinnning, and apparently gliding backward (i.e. away from the streamer, which was fluttering above and slightly in trail.) I've heard about a reverse glide or backdraft recovery, in this case however occuring in combination with horizontal spin AND the streamer.

Reason I am interested is that I have been messing with horizontal spin recovery and trying to come up with a way to do it WITHOUT having the rocket separate into two separate components (standard horizontal spin recovery , if there is such a thing, usually separates the nose cone which comes down by streamer.) It LOOK like I can probably leave the streamer on (at least to counterbalance the nose cone and prevent the horizontal spin from becoming a ballistic projectile). What was also interesting is that I did NOT have a swivel on, so apparently there was enough shock cord to handle the number of "twists."

Working name for this project is "Mkuki" (Swahili for Spear)

Oh yeah, went from 2 connecting fins to 3 connecting fins to get a good spin, this is a change from my prior attempt.

 

[hornet driver]

Pics-pics!

 

[BABAR]

Problem with my pics is that I am a Rocket Engineer ONLY, as different from the Engineer-Craftsmen. Hence you see a lot of raw balsa and unpainted and otherwise unfinished body tubes.

Pic 1 shows the Full Mkuki (that doesn't sound so good). Just over a meter long. I pulled out the streamer just to show it.

Pic 2 shows the tail view. Previous had only two side fins for the water wheel, this has been upped to 4, and it spun appropriately on descent.

Pic 3 shows the Sustainer Booster Junction. I had reinforced it for strength, as due to the length it tends to "bend" here. The reinforcement apparently "shrunk" the inner diameter a bit (used white glue....?), this was why it was "tight" and why stages failed to separate despite successful ignition of upper stage. You can see where it started to burn through the sidewall just below the reinforcement.

Pic 4 shows the end parts of Sustainer and Booster. The engine nozzle really looks black in real life, here it looks gray.

Pic 5 is cut away, showing that about 5 inches was burned INSIDE the forward end of the booster.

I've already repaired the sustainer. For reinforcement, I left and engine casing with some tape around it INSIDE the new forward end of the sustainer while the glue on the OUTSIDE reinforcment dries. This should retain the internal diameter and leave it just a little "loose" so I will get successful separating after upper stage ignition.

 

[hornet driver]

That's an interesting design to be sure---very cool--well named too. I had no idea it took on that much damage. Looking forward to your next attempt. Don't worry about the no paint thing,a pretty good number of the gang fly naked anyway! Thanks for the pics ---H

 

[SwingWing]

I have had a similar event(s) with an Edmonds stage 2 Thunder, which uses a 12" gap stage. I think that there is quite a bit of sideways lever force on the stage joint of rockets with a significant length on the booster tube, making them sensitive to not separtaing at staging. I have had the staging delay separation, (eventually separated, but upper stage thrust still roasted the stuffer tube) and just not separating. The Edmonds rockets, being glider designs, may put weird stresses on the joint due to lift of the gliders. Makes for some rather roasted stuffer tubes.

 

[BABAR]

Update 12/19

Perfect launch today C6-0 to A8-3. Arrow straight boost, nice staging and complete separation. Booster still came back ballistic, I think the 24" length is going to require a larger "water wheel" to successfully transition to horizontal spin. Sustainer had a nice flight. Unfortunately forgot to remove the tape holding the nose cone in place for transport (I loaded them up last night for flight today.) Doh!. Also Ballistic re-entry. This is of course why experimental birds are flown solo in isolation. Sustainer is an easy rebuild, just a minimum diameter streamer rocket 3FNC. Doesn't even need a launch lug.

 

[UncleVanya]

As per NAR protocol, launched solo in the field (not a soul in sight.)

Where is this protocol documented? I'm unfamiliar with it not questioning the truth of it.

 

[BABAR]

My interpretation of item 5 of NAR safety code. The more experienced members should feel free to correct me if i am misreading it.

 

[UncleVanya]

My interpretation of item 5 of NAR safety code. The more experienced members should feel free to correct me if i am misreading it.

Which code - LPR or HPR?

LPR says:

Launch Safety. I will use a countdown before launch, and will ensure that everyone is paying attention and is a safe distance of at least 15 feet away when I launch rockets with D motors or smaller, and 30 feet when I launch larger rockets. If I am uncertain about the safety or stability of an untested rocket, I will check the stability before flight and will fly it only after warning spectators and clearing them away to a safe distance. When conducting a simultaneous launch of more than ten rockets I will observe a safe distance of 1.5 times the maximum expected altitude of any launched rocket.

I would say that "no one in sight" is far in excess of what this is asking for - but no harm in doing that if you want to. The bad part is that if you have a bad event that catches things on fire - no one around to help you put it out...

 

[BABAR]

You are correct, now that I look at it I am going beyond the code. I fly in mostly in a public park. When I fly untested designs which my have "issues" even on low power, it is not unreasonable that they may come in 100 yards or more away from launch pad. The people around are doing their own things and not attentive to the launch (nor do I expect them to be.) So for me, when the code says to keep it safe, this is what I do. When I am at a club launch, our launch officers are appropriately strict about holding off on experimental launches until the spectators have left and only club members are around who know what "heads up!" means.

I guess my real intention is to make sure to emphasize safe launch practices especially with untested designs.

Of course, the REAL reason I fly these solo is that it saves a lot of embarassment when those "Houston, we have a problem" moments arise!

 

[boomtube]

“As per NAR protocol, launched solo in the field (not a soul in sight.)”

Was it Han Solo or Napoleon Solo that you launched?
I’m alone with this one aren’t I?

Are you building these rockets just to determine the maximum distance you can place motors and still get sustainer ignition, or is the distance the result of something else you are trying?

My last great failure with a staged rocket was one that used three motors in the booster and two in the sustainer. The sustainer motors ignited but instead of the stages separating the booster motors were blown out the back of their tubes leaving the exhaust of the sustainer motors to ignite the booster.

Then the delay charge on the third booster motor fired and deployed the chute for the booster while the rocket was still under thrust.

OHHHH!!! AWWWWW!!

 

[BABAR]

“As per NAR protocol, launched solo in the field (not a soul in sight.)”

Was it Han Solo or Napoleon Solo that you launched?
I’m alone with this one aren’t I?

Are you building these rockets just to determine the maximum distance you can place motors and still get sustainer ignition, or is the distance the result of something else you are trying?

My last great failure with a staged rocket was one that used three motors in the booster and two in the sustainer. The sustainer motors ignited but instead of the stages separating the booster motors were blown out the back of their tubes leaving the exhaust of the sustainer motors to ignite the booster.

Then the delay charge on the third booster motor fired and deployed the chute for the booster while the rocket was still under thrust.

OHHHH!!! AWWWWW!!

Probably wanting to see if I can set a record for gap staging (probably not--- most likely some other old fart has done it and not posted it.). Also exploring options for booster recovery OTHER than auxiliary chutes or streamers. I think my waterwheel horizontal spin recovery will eventually work, and the use of a longer booster brings back options for glider recovery on booster. What I have read about the Estes Black Widow is that the glide recovery of booster was not universally successful among all users.

Thanks for the story on your "last great failure"--- made me laugh and helps to know I am not the only engineer who has experienced entertaining yet suboptimal results.

I think my last attempted stretch of gap staging will be 36". Beyond that I am getting above what a low power rocket dude like myself can structurally handle. Will probably need to go to a D engine for that, not necessarily because of the mass but because I will need a big waterwheel to spin it down. Or could go with cluster with an A4-3T just to fire off an auxiliary booster chute. otherwise these long boosters tend to provide fine core samples on reentry.
Part of the challenge is that most of my designs (whopper flopper chopper, Gyskelion, sidewinder, Cerberus, triple sec, little deuce Scoupe ) don't easily lend themselves to simulation software testing.

Anyway, I am having fun, and keeps the squirrel on the wheel between my ears churning merrily away trying to come up with things that may not have been explored previously.