Cesaroni 54mm L640 Classic Dual Thrust: Help me understand Dual Thrust

NattyDread · Jul 22, 2014

this is the thrust curve for the engine: https://www.thrustcurve.org/simfilesearch.jsp?id=1619 Here is the regular L730 classic https://www.thrustcurve.org/simfilesearch.jsp?id=1428 I don't understand the significance of the dual thrust. I obviously see that the dual has a really high .75 seconds of thrust, then it sharply reduces. As opposed to a more gradual trail off. Help me understand when I might want to use this or what effect I am looking for on a 8foot, 7.5diameter 25LB rocket (weight with motor)

CarVac · Jul 22, 2014

NattyDread said:
this is the thrust curve for the engine: https://www.thrustcurve.org/simfilesearch.jsp?id=1619 Here is the regular L730 classic https://www.thrustcurve.org/simfilesearch.jsp?id=1428 I don't understand the significance of the dual thrust. I obviously see that the dual has a really high .75 seconds of thrust, then it sharply reduces. As opposed to a more gradual trail off. Help me understand when I might want to use this or what effect I am looking for on a 8foot, 7.5diameter 25LB rocket (weight with motor)

Use it when you want a kick off the pad and a long burn at the same time. A moonburner will not give you as much of a kick, merely dragging out the burn from a relatively low initial thrust.

I imagine this to be a decent motor for a rocket as unstable as a V2.

blackjack2564 · Jul 22, 2014

Well it is, just was is says it is................ Dual thrust. Two motors in one!

1 grain of V-max to kick it in the butt & get a heavy or larger diameter rocket of the pad safely. Then Classic to keep on going.

Then tone it down to a more normal thrust to keep it going.

In this case you start with 300+ lbs [spike]of thrust dropping to 125lbs for 2.75 sec.then tapering off to 0 [approx.]

Good for windy days. Heavier rockets come up to safe speed quicker.

Or just smacking a rocket into another dimension.

One of my favorites.

I'm waiting for Dual Thrust Mellows.......now you are talking. Wham it....then central core long burn with no coning!

Actually I like it in my 6in Ultimate Endeavor . No other 54 in the center gets this rocket moving quicker & carries it higher. Mine is 28lbs on the pad. Will go high 3's [3800-3900 ft]

It is EXACTLY what you want to use in a large heavy rocket like you describe .

NattyDread · Jul 22, 2014

Very interesting insight, Jim.

blackjack2564 said:
Well it is, just was is says it is................ Dual thrust. Two motors in one!

1 grain of V-max to kick it in the butt & get a heavy or larger diameter rocket of the pad safely. Then Classic to keep on going.

Then tone it down to a more normal thrust to keep it going.

In this case you start with 300+ lbs [spike]of thrust dropping to 125lbs for 2.75 sec.then tapering off to 0 [approx.]

Good for windy days. Heavier rockets come up to safe speed quicker.

Or just smacking a rocket into another dimension.

One of my favorites.

I'm waiting for Dual Thrust Mellows.......now you are talking. Wham it....then central core long burn with no coning!

Actually I like it in my 6in Ultimate Endeavor . No other 54 in the center gets this rocket moving quicker & carries it higher. Mine is 28lbs on the pad. Will go high 3's [3800-3900 ft]

It is EXACTLY what you want to use in a large heavy rocket like you describe .

Salvage-1 · Jul 22, 2014

Just as Crazy J sayz.....

one addition, in a lighter weight rocket, this looks to be a good way to 'smack thru mach' whilst still having the tapered off thrust to continue it going.

Threemorewishes · Jul 22, 2014

I used one in a 3 inch diameter, 11 pound rocket and got 14,500 feet at LDRS30. It was windy but the rocket flew straight as an arrow due to the initial kick in the pants.

HeavyLight · Jul 22, 2014

You probably already saw but CTI's Youtube channel has a static firing of the prototype. It's simply awesome to watch.

markkoelsch · Jul 23, 2014

blackjack2564 said:
Well it is, just was is says it is................ Dual thrust. Two motors in one!

1 grain of V-max to kick it in the butt & get a heavy or larger diameter rocket of the pad safely. Then Classic to keep on going.

Then tone it down to a more normal thrust to keep it going.

In this case you start with 300+ lbs [spike]of thrust dropping to 125lbs for 2.75 sec.then tapering off to 0 [approx.]

Good for windy days. Heavier rockets come up to safe speed quicker.

Or just smacking a rocket into another dimension.

One of my favorites.

I'm waiting for Dual Thrust Mellows.......now you are talking. Wham it....then central core long burn with no coning!

Actually I like it in my 6in Ultimate Endeavor . No other 54 in the center gets this rocket moving quicker & carries it higher. Mine is 28lbs on the pad. Will go high 3's [3800-3900 ft]

It is EXACTLY what you want to use in a large heavy rocket like you describe .

Jim, I would prefer it in a minimum diameter rocket with smallish fins. The rapid boost phase would get it to speed so the small fins should be effective, and then on to a more reasonable thrust level. Would kick ass me thinks. Alas, my home field is Bong, and such a rocket should blow the waiver by a substantial margin.

Mark Koelsch
Sent from my iPhone using Rocketry Forum

AlnessW · Jul 23, 2014

blackjack2564 said:
Well it is, just was is says it is................ Dual thrust. Two motors in one!

1 grain of V-max to kick it in the butt & get a heavy or larger diameter rocket of the pad safely. Then Classic to keep on going.

Thanks for the explanation Jim - I never quite understood the concept of "Dual Thrust" until now. (Such as the K590, L640, etc.) Now I see that you could compare it to the Aerotech 54/2560 K375NW - it boosts on a grain of Warp-9 propellant, then continues on White Lightning. (Got one of those motors to fly this weekend, by the way.

)

cvanc · Jul 23, 2014

Let's flesh this out a little bit. I don't quite see how this works.

Is the 'hot' grain down at the bottom, by the nozzle? Or is it at the top of the stack?

Wouldn't the hot grain burn rapidly to the liner wall and then leave the liner exposed for the duration of the slower propellant burn, risking a liner burn-through?

Also, if it's at the bottom, wouldn't the upper grains just slide down to the rear of the casing? Or worse, slump down and potentially spit?

How are these potential issues dealt with - or am I looking at it all wrong?

Thanks...

CarVac · Jul 23, 2014

cvanc said:
Let's flesh this out a little bit. I don't quite see how this works.

Is the 'hot' grain down at the bottom, by the nozzle? Or is it at the top of the stack?

Wouldn't the hot grain burn rapidly to the liner wall and then leave the liner exposed for the duration of the slower propellant burn, risking a liner burn-through?

Also, if it's at the bottom, wouldn't the upper grains just slide down to the rear of the casing? Or worse, slump down and potentially spit?

How are these potential issues dealt with - or am I looking at it all wrong?

Thanks...

I know not how the CTI 54mm and 24mm ones work, but the AT K375 has a thick paper tube outside the base W9 grain which keeps the upper ones from sliding down. The 75mm CTI I am fairly confident needs grains to be bonded to the liner, preventing them from sliding.

The liner probably doesn't care too much, because the low thrust portion of the burn is lower pressure and likely cooler temperature than a normal motor.

GaryT · Jul 23, 2014

Awesome Motor.

[video=youtube_share;wsgOGXGURWk]https://youtu.be/wsgOGXGURWk[/video]

blackjack2564 · Jul 23, 2014

markkoelsch said:
Jim, I would prefer it in a minimum diameter rocket with smallish fins. The rapid boost phase would get it to speed so the small fins should be effective, and then on to a more reasonable thrust level. Would kick ass me thinks. Alas, my home field is Bong, and such a rocket should blow the waiver by a substantial margin.

Mark Koelsch
Sent from my iPhone using Rocketry Forum

Yep... I've flown them in smaller rockets [3in.] and they beg for mercy.....but they get up there with a quickness! LOL:y:

Someday I WILL stick one in a minimum SpaceCowboy. I would expect 20,000 + easily.

Jeroen_at_CTI · Jul 23, 2014

blackjack2564 said:
Someday I WILL stick one in a minimum SpaceCowboy. I would expect 20,000 + easily.

Easily indeed. John Wilke flew his KestreL to over 27,000 ft with this motor.

Jeroen.

NattyDread · Jul 24, 2014

Hi, what was the weight on this rocket either loaded or unloaded with motor??

GaryT said:
Awesome Motor.

[video=youtube_share;wsgOGXGURWk]https://youtu.be/wsgOGXGURWk[/video]

bobkrech · Jul 24, 2014

cvanc said:
Let's flesh this out a little bit. I don't quite see how this works.

Is the 'hot' grain down at the bottom, by the nozzle? Or is it at the top of the stack?

Wouldn't the hot grain burn rapidly to the liner wall and then leave the liner exposed for the duration of the slower propellant burn, risking a liner burn-through?

Also, if it's at the bottom, wouldn't the upper grains just slide down to the rear of the casing? Or worse, slump down and potentially spit?

How are these potential issues dealt with - or am I looking at it all wrong?

Thanks...

Read this set of special instructions from CTI regarding the Dual Thrust motors. https://www.pro38.com/pdfs/Pro75_notes_V1.8.pdf

Bob

NattyDread · Jul 24, 2014

bobkrech said:
Read this set of special instructions from CTI regarding the Dual Thrust motors. https://www.pro38.com/pdfs/Pro75_notes_V1.8.pdf

Bob

My question was for the 54mm L640. Not mentioned in the cesaroni notes u mentioned

bobkrech · Jul 24, 2014

NattyDread said:
My question was for the 54mm L640. Not mentioned in the cesaroni notes u mentioned

Pro54 motor reloads are factory preassembled within the liner so you do not have to put the reload module together which is why they don't describe the innards.

You asked how dual thrust motors were configured and the Pro75 instructions illustrates the internal configuration of the propellant grains which I why I referred it to you.

Bob

GaryT · Jul 24, 2014

NattyDread said:
Hi, what was the weight on this rocket either loaded or unloaded with motor??

My GIZMO XL weighs 23lbs all ready to fly (No Motor) On the pad weight was 28lbs. Altitude was 4008'

AlnessW · Jul 24, 2014

Great photo!

NattyDread · Jul 25, 2014

bobkrech said:
Pro54 motor reloads are factory preassembled within the liner so you do not have to put the reload module together which is why they don't describe the innards.

You asked how dual thrust motors were configured and the Pro75 instructions illustrates the internal configuration of the propellant grains which I why I referred it to you.

Bob

. You are a mad scientist, Bob! Learned a lot. I assumed all cesaroni motors were assembled and now understand your point! Thanks. Cool data! Thanks for sharing

NattyDread · Jul 25, 2014

GaryT said:
My GIZMO XL weighs 23lbs all ready to fly (No Motor) On the pad weight was 28lbs. Altitude was 4008'

Is that automotive paint? Noice!

bobkrech · Jul 25, 2014

Nah. Chrome Dome with Future. :wink:

Oh! You mean the rocket! :facepalm:

Bob

Cesaroni 54mm L640 Classic Dual Thrust: Help me understand Dual Thrust

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