CC express 3 stage

I got an Estes CC express and lost it, and was so satisfied that I got another. But I got the Booster back, so I kept it and am planning on flying it 3 stages. Has anyone else done this?

I've never done a 3 stage, but I flew my CC Express for the first time today for 2 perfect flights on a D12-0/D12-5 combination. This was my first ever 2 stage rocket & it performed beautifully!
I built it completely stock per the instructions & used 1 wrap of scotch tape & it flew flawlessly! I'm thinking about switching the 12" chute for a streamer though.

I did that yesterday, and flew great. Estes' altitude estimation is way under reality. I agree that for that altitude, a streamer would work better

Originally posted by CATO
I did that yesterday, and flew great. Estes' altitude estimation is way under reality. I agree that for that altitude, a streamer would work better

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i dont think estes' altitude sims are under estimated, i think they are rather overestimated, just because a rocket "looks" high, doesnt mean it is any higher than any sim would say it was, you have nothing to compare it to!
if you put in an altimeter and then told me that the altitude was higher than what estes said, id be surprised.

i managed to destroy my CC express when the streamer detached.Its a fine kit and it will be replaced

Originally posted by CATO
I got an Estes CC express and lost it, and was so satisfied that I got another. But I got the Booster back, so I kept it and am planning on flying it 3 stages. Has anyone else done this?

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I think you should go for it! A D12-0/D12-0/D12-5 combo would be very cool. I would recommend painting the sustainer black for visibility at those altitudes. I painted my booster stage neon pink which really helps in recovery.
-and of course use a streamer!-but I'm sure you already know that!
I need to pick me up some black crepe paper for my streamer conversion-shouldn't be too hard to find this time of the year.

Cato,

Same thing happened to me also and I thought the same thing as you. I am presently building my "CCC Express" but will probably stage it D12/D12/E9-8. I did a SpaceCad simulation and the three stage is stable with a predicted altitude of 2 800 feet.

Thinking about it, I find it strange that , to my knowledge, no manufacturer offers a 3 stage D engine rocket!

Good luck and let me know how yours turns out!

Mine dosen't have the modified sustainer for Es, and rocksim says that ddd goes HIGHER than dde. It will go next CMASS launch, provided that the visiblity's fine

2800 feet wow that really hi would u be able to see the tracing smoke??

Try modifying the fin configuration for less drag. Sweep them back a bit more without reducing surface area, reduce them from four to three.....

Mix it up a bit and you'll pick up a few hundred feet on your largest motor combos.









:kill:

It brushed with the speed of balsa earlier, losing one fin on the sustainer, so it is now three fins (I swithced glues so it will be much stronger and have a higher speed of balsa now)

I put the new config in rocksim, it says 2914ft

Originally posted by CATO
It brushed with the speed of balsa earlier, losing one fin on the sustainer, so it is now three fins (I swithced glues so it will be much stronger and have a higher speed of balsa now)

I put the new config in rocksim, it says 2914ft

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what the heck is speed of balsa??????

He didn't reach the speed of balsa - I think it is impossible with Estes motors unless you have a huge high aspect ratio fin. He reached the speed of glue. The speed of x is the speed at which the aerodynamic forces on x is higher than the ability of material x to take the strain. This is an example of a rocket that hit the speed of balsa: https://www.rocketryforum.com/attachment.php?s=&postid=228438
Note that the fins snapped off and the balsa itself failed - the fins didn't just come off at the root.

Originally posted by Jacques
D12/D12/E9-8. I did a SpaceCad simulation and the three stage is stable with a predicted altitude of 2 800 feet.

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Jacques,
I'm really curious as to what SpaceCad said was the speed at the end of the launch rod for that combination.

A D12 lifting another D12 and an E9, plus 3 stages of rocket, is really pushing what a D12 will safely lift off the pad.

I did a RockSim simulation of the same combination and it suggests the rod speed is a little too slow off a 36" rod to be stable. (see attached)

It also suggests that without any wind, and ignoring the instability problem, max altitude is ~3400 feet.

A safer combination to get to 2800 feet is to use a D12 to E9 2-stage combination, and use 3 fins (of the standard kit shape) on the booster and sustainer instead of 4. That combo still has a good margin of stability and adequate speed off the rod to not be a problem.

Originally posted by Gus
Jacques,
I'm really curious as to what SpaceCad said was the speed at the end of the launch rod for that combination.

A D12 lifting another D12 and an E9, plus 3 stages of rocket, is really pushing what a D12 will safely lift off the pad.

I did a RockSim simulation of the same combination and it suggests the rod speed is a little too slow off a 36" rod to be stable. (see attached)

It also suggests that without any wind, and ignoring the instability problem, max altitude is ~3400 feet.

A safer combination to get to 2800 feet is to use a D12 to E9 2-stage combination, and use 3 fins (of the standard kit shape) on the booster and sustainer instead of 4. That combo still has a good margin of stability and adequate speed off the rod to not be a problem.

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At one time, the Tuber was going to be a D-D-E model. Turns out that combination is just a little too heavy for safe flight from most pads. I believe Rocksim said we needed about 7 feet of rod before the model would be traveling fast enough for stable flight.

Our one and only test flight of that configuration was done with a 4 foot launch rod. The rocket did a gravity turn and headed downrange pretty quick.

D-E flights, on the other hand, are no problem.

Originally posted by Rob Fisher
I think you should go for it! A D12-0/D12-0/D12-5 combo would be very cool. I would recommend painting the sustainer black for visibility at those altitudes. I painted my booster stage neon pink which really helps in recovery.
-and of course use a streamer!-but I'm sure you already know that!
I need to pick me up some black crepe paper for my streamer conversion-shouldn't be too hard to find this time of the year.

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No,no,no-don't do this! very bad-go with Gus's advice.
Now I need to pick up another CC so I can build it 3 finned with the sustainer set-up for E's so I can hit 2,800'

Originally posted by CATO
...and rocksim says that ddd goes HIGHER than dde.

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When I do a RockSim with D12-D12-D12 I get 2720' and it is still not stable off the pad.

Originally posted by Jacques
Thinking about it, I find it strange that , to my knowledge, no manufacturer offers a 3 stage D engine rocket!

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This thread is an illustration of why no manufacturer offers one.

The CC Express although not a minimum diameter model, is pretty close to one. Even under zero-wind conditions a 3 stage DDD rocket would be barely stable off a 36" rod. Any rocket going unstable right off the pad, and then becoming stable as it loses motor weight, is a dangerous rocket. A 3 stage version would be even more dangerous.

This is not to say that a DDD combination is always going to go unstable, but the potential is so high that no manufacturer could responsibly offer one for sale.

My suggestion is that if you want a 3 stager, go with the Estes Comanche, a well-proven stable flyer.

If it's height you're after, try an Apogee Aspire on Apogee's slow burning F-10.

and what if you have a bigger launch rod? ex tarc standard (6ft, .25 in) i'm not suggesting any kits, I just want to do it on my own with a less than standard pad.

Originally posted by CATO
and what if you have a bigger launch rod? ex tarc standard (6ft, .25 in) i'm not suggesting any kits, I just want to do it on my own with a less than standard pad.

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\
you seem to really want to lose this thing! lol.

Sorry, nowhere near mach. My sims put a 3 stage CC express on D12-0 to D12-0 to E9-8 at mach .51 (385mph) peak velocity, and stable after 4.8' of rod (so a 6' rod is fine). I also get 3615' for this combo. On 3 D12's I get Mach .52 (392mph) and 2890 feet (these are using another stock booster stage on the bottom). Liftoff mass is 7.6oz for the 3 D12's, and 8.382oz on 2 D12's and an E9. Both of these are well within Estes D12 max liftoff weight of 14oz. Laminating the fins with epoxy or glassing them will just add weight and detract from stability. My advice would be to use regular wood glue for the fins, and pay a lot of attention to their straightness. Out of line fins will put a lot more stress on them, as well as drastically reducing the altitude.

Originally posted by outasight13
\
you seem to really want to lose this thing! lol.

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cc express is, in my opinion, one of the better kits ever produced, so what does one do with it? LOSE IT for an excuse to get another, lol.

Also, It will be just too cool for words

The fins are on there with about 8 gallons of wood glue

Originally posted by outasight13
...your rocket might attain a speed close to mach 1

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This rocket won't get anywhere near mach 1 (look at the pdf attached above, max velocity 395mph). Adding fiberglass or epoxy to the fins is not only unnecessary, but will add weight to the back end of a rocket already marginally stable at lift off, making it even more dangerous.

Originally posted by CATO
and what if you have a bigger launch rod? ex tarc standard (6ft, .25 in) i'm not suggesting any kits, I just want to do it on my own with a less than standard pad.

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If you don't know, and don't know how to figure that out, then you should hold off until you do. Learning to use RockSim is a good place to start. It will teach you a lot and help keep you out of trouble.

Actually, I was getting a margin of 1.8-2.1 calibers fully loaded - not even close to marginally stable. This was with 4 fins per stage, though.

Originally posted by Gus
This rocket won't get anywhere near mach 1 (look at the pdf attached above, max velocity 395mph). Adding fiberglass or epoxy to the fins is not only unnecessary, but will add weight to the back end of a rocket already marginally stable at lift off, making it even more dangerous.


If you don't know, and don't know how to figure that out, then you should hold off until you do. Learning to use RockSim is a good place to start. It will teach you a lot and help keep you out of trouble.

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I know how to find that out, just have found rocksim a bit innaccurate on this type of thing in the past, and wanted a second opinion.

Originally posted by cjl
Actually, I was getting a margin of 1.8-2.1 calibers fully loaded - not even close to marginally stable. This was with 4 fins per stage, though.

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You have to be going a minimum speed for Barrowman aerodynamic stability calcs (or RockSim stabilit calcs, for that matter) to apply.


Sure, your model may have a 2.0 stability margin at a velocity of 500 fps.


At 10 fps, it may just fly like a shot-put rock.

If your rocket isn't going fast enough when it leaves the launch rod, the fins are meaningless.



If your loaded stack (3 or 4 stages of Estes D engines) weighs sooooo much that the bottom-most booster can't accelerate the resultant stack of rocket to sufficient velocity for the aerodynamic forces to take over and make it stable by the time it leaves the launch rod, it will fly unstable until it reaches that velocity or it spits some weight.



RockSim calculated stability margins be damned. If it ain't going fast enough when it leaves the rod, it ain't stable. Period. So what if the margin is 7,000,000. If the velocity at 3' is 2 fps, and the acceleration is too slow, the thing is falling over and dying. Period.

I was getting 38mph at 4'8" and 27mph at 2'9". That is about 55fps at 4'8" and 40fps at 2'9". That is plenty fast ( I gave the weights - why do you not believe them?)

Glue on a few 18mm booster MMs between the fins, add cones, throw some C6's in them, and you'll have your minimum rod speed problem solved, plus a couple hundred feet more alt. Cluster multistage baby.

Originally posted by Lugnut
Glue on a few 18mm booster MMs between the fins, add cones, throw some C6's in them, and you'll have your minimum rod speed problem solved, plus a couple hundred feet more alt. Cluster multistage baby.

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I've often considered doing this to my Fliskits Praetor to get some more altitude out of her. Those huge fins really slow her down,-though that is kind of the point of that rocket.