New Cesaroni 54mm L265 Mellow Motor: 9.9 Second burn

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NattyDread

NattyDread

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Anyone try one of these out? The thrust to weight ratio works for my stretch V2, 408oz, 98 inch tall, Dual Deploy. Had maiden voyage at rocctock. when I rocksim this new motor, I get a red arrow and it flies to the left, see picture. I still don't understand what this means in rocksim..... See the thrustcurve info here: https://www.thrustcurve.org/simfilesearch.jsp?id=2062
L265 Rocksim pic.jpg

Just wanting to make sure I am not missing something in this motor?

Video of stretch V2: https://www.youtube.com/watch?v=MTO9VeBSXf8
 
Do you have your launching conditions set to very windy? It is the only thing that comes to my mind.


Alexander Solis

Level 1 - Mariah 54 - CTI-I100 Red Lightning Longburn - 6,345 Feet
 
NattyDread said:
Anyone try one of these out? The thrust to weight ratio works for my stretch V2, 408oz, 98 inch tall, Dual Deploy. Had maiden voyage at rocctock. when I rocksim this new motor, I get a red arrow and it flies to the left, see picture. I still don't understand what this means in rocksim..... See the thrustcurve info here: https://www.thrustcurve.org/simfilesearch.jsp?id=2062
View attachment 178016

Just wanting to make sure I am not missing something in this motor?

Video of stretch V2: https://www.youtube.com/watch?v=MTO9VeBSXf8
Click to expand...

It means not enough thrust. The L265 roughly will fly 11lbs.....loaded.
 
I uploaded the file and tried it out on my Mariah 54 rocksim file. It worked fine for me, perhaps tbone is correct that it might not be enough thrust. It is either that or my other guess is that your launch guide length in rocksim is too short. What motor did you use on that video you uploaded?
 
SinfulDarkLord said:
I uploaded the file and tried it out on my Mariah 54 rocksim file. It worked fine for me, perhaps tbone is correct that it might not be enough thrust. It is either that or my other guess is that your launch guide length in rocksim is too short. What motor did you use on that video you uploaded?
Click to expand...
K650 smokey Sam. Both engines have similar thrust, and should carry the weight.
 
NattyDread said:
K650 smokey Sam. Both engines have similar thrust, and should carry the weight.
Click to expand...

I have no doubts that it has to do with your launching condition settings in rocksim. Either the launch guide length is too short or it could be that the wind is set to windy, also it could be both. Check the settings and see if they are set right.
 
I'm with Tbone, the L265, in spite of a decent kick off the pad, doesnt seem to me to have the average thrust you
need for your 25lb+(408 oz) flight vehicle. The burn is a glorious 10 seconds but the average thrust looks to be
more suited for a rocket in the 10-15 pounds range. Perhaps you could adjust the mass over ride down to say 10
pounds (temporarily) and re-run the sim and see if you get a straighter/ more vertical flight.
 
V2's aren't the greatest idea for long-burning motors...
 
This is exactly the problem with using the average thrust to determine what rocket it will lift, and why simulators show you speed at the end of the launch guide. It doesn't matter what the average thrust is across the entire burn, only what the thrust is at the beginning and how quickly the rocket reaches a speed where the fins are effective.
 
NattyDread said:
K650 smokey Sam. Both engines have similar thrust, and should carry the weight.
Click to expand...

Natty, Go back and reread Modern High Power 2, the section on propulsion. The other posts are correct. The avg. thrust of the K650 is ca 650 newtons (ca, 148 pounds of thrust), which is ca. 2.4 times the avg. thrust of the K265 (265 newtons is ca. 60 pounds of thrust). A rocket with the K300 and K265 will weather cock in windy conditions even on a 10 pound rocket. Those motors are made for small, light rockets to achieve high altitudes. A 25 pound rocket is nearly an L3 bird and requires ca. 125 pounds of thrust to lift off safely. You would not want to launch with an average thrust much less than a "650" in the motor title, i.e. K650, L650, etc. Good luck with your motor selection and rocket.
 
4kids49 said:
Natty, Go back and reread Modern High Power 2, the section on propulsion. The other posts are correct. The avg. thrust of the K650 is ca 650 newtons (ca, 148 pounds of thrust), which is ca. 2.4 times the avg. thrust of the K265 (265 newtons is ca. 60 pounds of thrust). A rocket with the K300 and K265 will weather cock in windy conditions even on a 10 pound rocket. Those motors are made for small, light rockets to achieve high altitudes. A 25 pound rocket is nearly an L3 bird and requires ca. 125 pounds of thrust to lift off safely. You would not want to launch with an average thrust much less than a "650" in the motor title, i.e. K650, L650, etc. Good luck with your motor selection and rocket.
Click to expand...
agreed. I think I hit the wrong button on my calculator when I was looking at the motor. :)
 
JohnCoker said:
This is exactly the problem with using the average thrust to determine what rocket it will lift, and why simulators show you speed at the end of the launch guide. It doesn't matter what the average thrust is across the entire burn, only what the thrust is at the beginning and how quickly the rocket reaches a speed where the fins are effective.
Click to expand...
John, are you saying that rocksim will accurately predict if there is enough thrust to get off the pad? And/or am I looking at the thrustcurve graph to see the initial thrust level?
 
Yes, the simulators will give you the speed of the rocket at the end of the launch guide, which is what really matters. The ThrustCurve.org motor guide also does this, which is my some motors that don't meet the "5:1 ratio" might work and why some that do meet it might not.

Note that it's not "enough thrust to get off the pad," but enough thrust to get the rocket going fast enough that the fins are effective before the end of the launch guide (rail or rod). A commonly accepted minimum velocity is 15m/s or 50fps or 34mph. Note that this also is just a rule of thumb, but at least one that factors in the shape of the thrust curve at the start of the flight.
 
John's Thrust Curve is great. I use it all of the time. But CTI's site also gives the thrust curves and motor info. for each CTI motor. Very good source of info. for CTI motors.
 
SinfulDarkLord said:
Can you please post the rocksim file. I'd very much like to take a look.
Click to expand...
The first post had a link: thrustcurve.org/simfilesearch.jsp?id=2062.

When you look at this motor, notice that it's quite regressive (thrust reduces during the burn), which means that the highest thrust is at the beginning. So, the thrust at the start of the flight is actually higher than the average thrust, meaning it would potentially work for a heavier rocket than the 5:1 ratio would suggest.
 
JohnCoker said:
The first post had a link: thrustcurve.org/simfilesearch.jsp?id=2062.

When you look at this motor, notice that it's quite regressive (thrust reduces during the burn), which means that the highest thrust is at the beginning. So, the thrust at the start of the flight is actually higher than the average thrust, meaning it would potentially work for a heavier rocket than the 5:1 ratio would suggest.
Click to expand...

I had no doubts that this motor configuration could do it. I am certain his simulation is merely an issue of wrong settings on the launch conditions. Two of, which I have no doubts is the launch guide length and the wind settings.

My apologies for the confusion John, but I meant for NattyDread to post the rocksim design so that I may take a look at it.

Please if you dont mind sharing NattyDread.


Alexander Solis

Level 1 - Mariah 54 - CTI-I100 Red Lightning Longburn - 6,345 Feet
 
View attachment V2 LOC 7.5dual deploy mod Build May 2014.rktHere is the rocksim file. Its certainly the biggest rocket I have built. The weights are accurate with paint on, chutes loaded, etc. It is very bottom heavy because of the reinforcement I put in it. You cant glue to a poly nose cone very well.... Started with a locv2 7.5" then added the Dual deploy with 2 altimeters.
SinfulDarkLord said:
Can you please post the rocksim file. I'd very much like to take a look.
Click to expand...
 
Natty,

Does the weight include motor case and reload? I can't read Rocksim.
 
My apologies for the late response. It appears that due to the 2.45 margin it is very easy for this rocket to weathercock.

I ended up getting the same effect like you did in the simulation on a 3-7MPH wind. You definitely want to fly it with no wind to get a straight boost.


Alexander Solis

Level 1 - Mariah 54 - CTI-I100 Red Lightning Longburn - 6,345 Feet
 

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