punisher rkt altitude

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watermelonman

watermelonman

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What are Punisher fliers using for simulation files, and how accurate have they been? I have not so much as compared my built weight to the listed, but my flights have been way, way off. Like 4300 feet on a J when the simulation reported 5800 feet. Obviously the rocket is tons of fun as is and I am not concerned with setting any altitude records here, but clearly some part of the equation is incorrect. My finish is not the smoothest, but not what I would expect to be notably rough.
 
Try Thrustcurve.org for a baseline, I find that ROCsim is too optimistic most of the time.

Kenny
 
Typically Rocksim, unless you are very accurate , will overestimate by about 10%.

Now, that being said I think you need to make sure you sim matches your build. Weights are important as are location of the weights. This included epoxy mass for fillets as they can add some mass. Surface finish is another issue- do not choose polished as that is almost impossible to achieve.
 
watermelonman said:
What are Punisher fliers using for simulation files, and how accurate have they been? I have not so much as compared my built weight to the listed, but my flights have been way, way off. Like 4300 feet on a J when the simulation reported 5800 feet. Obviously the rocket is tons of fun as is and I am not concerned with setting any altitude records here, but clearly some part of the equation is incorrect. My finish is not the smoothest, but not what I would expect to be notably rough.
Click to expand...
The problem is that the "CD" (coefficient of drag) is sort of a general-purpose fudge factor in these simulations. What you can do is get actual altitude, then adjust the CD until the simulated altitude matches. That'll give you a usable value for other motors (at least sub-sonic flights).
 
2 flights on my Punisher:
J250 - actual alt = 4090', OR sim = 4190' Thrst crv sim = 4120'
J280 - actual alt = 4300', OR sim = 4340', Thrst crv sim = 4260'
 
timbucktoo said:
2 flights on my Punisher:
J250 - actual alt = 4090', OR sim = 4190' Thrst crv sim = 4120'
J280 - actual alt = 4300', OR sim = 4340', Thrst crv sim = 4260'
Click to expand...

Very rare observations. In order to match Thrustcurve's "quick and dirty" simulations, your flights must have been perfect - 1D trajectory, nominal weather conditions, motors that actually burned like the spec sheets say ....
 
Flew an L935 yesterday to 17,395

With Aeropack tail cone
 
GRIFFIN said:
Flew an L935 yesterday to 17,395

With Aeropack tail cone
Click to expand...

Oh dear. That smashes even the 14k simulation. Mine hit 9900 feet, though it did take off at a bad angle that cost it probably 2000 feet. What the heck is wrong with mine.
 
watermelonman said:
What are Punisher fliers using for simulation files, and how accurate have they been? I have not so much as compared my built weight to the listed, but my flights have been way, way off. Like 4300 feet on a J when the simulation reported 5800 feet. Obviously the rocket is tons of fun as is and I am not concerned with setting any altitude records here, but clearly some part of the equation is incorrect. My finish is not the smoothest, but not what I would expect to be notably rough.
Click to expand...

Always weigh the rocket before launch. You would be amazed. Also, use a range of drag coefficients.
I personally discover that first simulations are good to about 20% for altitude.
You are off, here by 35%. Really. Weigh the thing.
 
I flew mine to 16,661ft with out the tail-cone. L-935 CTI

10,306 with K-1103-Propellent X Aero-Tech

8,980 ft with CTI 3 grain Classic.

5180ft J-275 AT [2-grain]


3011 ft I-435-T [38 wimp adapter]

All sims were WAY short.

Punisher's are the .50 caliper bullet of the rocket world!

Dead straight flights in 35 mph with 0 weather cocking.
It weighs exactly 5 lbs. ready to fly without motor.
 
Last edited:
blackjack2564 said:
Punisher's are the .50 caliper bullet of the rocket world!

Dead straight flights in 35 mph with 0 weather cocking.
It weighs exactly a lbs ready to fly without motor.
Click to expand...

What's your dry weight?
Are you saying as long as my stability is 0.5 or better, she's stable?
 
JohnCoker said:
The problem is that the "CD" (coefficient of drag) is sort of a general-purpose fudge factor in these simulations. What you can do is get actual altitude, then adjust the CD until the simulated altitude matches. That'll give you a usable value for other motors (at least sub-sonic flights).
Click to expand...
My experience agrees with John's thought here. I use both Thrustcurve and RockSim and compare the projected results. But I also weight and measure every aspect of my builds so that my Rocksim models mimic as-built rocket parameters down to the smallest detail - e.g. hardware, epoxy, paint, etc.

After the first flight I go back to both Thrustcurve and Rocksim and adjust their respective Cds to get their estimated altitudes close to the actual result. On my Painkiller Micro, both Cds are set at 0.68 and the altitudes for a full range of motors is within 100 ft (up to 3,300 ft).

It has seemed to work well so far.
 
The Min-wax was still drying on my Punisher last weekend at Airfest. It went up to 14300' and change on a CTI L265 longburn motor on Sunday. Rocsim predicted 14438 so that was pretty close but it did weathercock into the wind as was found (thanks Brad) about a third of a mile upwind. I suspect a flight on a calm day might get another 1000' to 1500' on that motor.
 
This all serves to confirm, my Punisher performance is nowhere near what others see. I still enjoy flying it, of course, but I want to see the 14-17k others are getting instead of the 9-10k seen so far on 6XL motors.

At XPRS I am going to gut all electronics except a simple altimeter and maybe a tiny tracker, and fly it on a J295 to match CJ, will see what I get. Of course I will also put it on a scale, would like to weigh it now but out of town.
 
blackjack2564 said:
I flew mine to 16,661ft with out the tail-cone. L-935 CTI

10,306 with K-1103-Propellent X Aero-Tech

8,980 ft with CTI 3 grain Classic.

5180ft J-275 AT [2-grain]


3011 ft I-435-T [38 wimp adapter]

All sims were WAY short.

Punisher's are the .50 caliper bullet of the rocket world!

Dead straight flights in 35 mph with 0 weather cocking.
It weighs exactly a lbs ready to fly without motor.
Click to expand...

Jim, why were you flying in 35 mph winds?
 
timbucktoo said:
What's your dry weight?
Are you saying as long as my stability is 0.5 or better, she's stable?
Click to expand...

No, he is not advocating a static margin of .5- at least I sincerely doubt it. What he is referring to is the ballistic coefficient of a 50 caliber bullet- it it very high and as such is not affected by wind nearly as much as bullets with a lower ballistic coefficient.
 
markkoelsch said:
Jim, why were you flying in 35 mph winds?
Click to expand...

He is referring to the winds aloft.

As far as the discussion of weight. The highest altitude rocket was not one of the lighter ones. I will post my dry weight when I clean all the Kansas off of it.
 
On Saturday at Airfest I got my punisher up to 15006 ft on an CTI L990, not remarkable unless you look at the FPS. The RRC3 recorded the top speed at 3884fps which made the melted paint on the nosecone and forward sections of the fins that much cooler to look at.

Jason might have beat my height, but I've got him in belching and speed...
 
I wasn't ready to fly in time for the contest (and I was using a Telemega). L1030 gave me 15138 on the baro and 16191 on GPS (full lock on the entire flight). It hit 1392mph for a top speed. I flew Monday a few minutes after 11AM.

Flight data from the Telemega.
Screenshot from 2015-09-08 19:50:10.png

Doug
 
Stock Punisher I was referring to weighed 5 lbs. on the dot. [damn auto correct changed 5 to"a'' for some strange reason. Did it again here but i caught it]

Stability was 1.99 [2]

Actually , one I flew in contest was the sustainer for 2-stage. It has 1 lb. of nose weight, 2 altimeters, new MissleWorks GPS, 3-9v. add another .5 lbs. That's a lot of crap on a 2.5 x 5.5 sled.
Stability of 2.15
By the way GPS worked great for Alpha test!

Sims showed 13, 403 ft. Actual was 16,661.
All my sims for Punisher are WAY under. It's flown on motor as small as 3 grain 38 to 6xl 54 and stable on everything in between.
WaterMM you must have other issues if not getting altitude. Fins on straight? Altimeter off?

Jason used a tailcone in unlimited class, was stock other than that. I'm guessing he was at 5.25 lbs and beat me by 800 some ft.[17,400 something?] That was the tailcone. other flights showed the added weight paid off for this high trust type motor.
Hit 2432 ft/sec...um mach 2.1

Here's the first peek at MW GPS.....

DSCN5149.jpg DSCN5157.jpg

Same screw hole pattern as RRC3 & .25in wider and .5 in longer if memory serves.

By the way, this thing IS the .50 bullet of rockets. It's scary stable in winds.
 
Last edited:
bluerue said:
On Saturday at Airfest I got my punisher up to 15006 ft on an CTI L990, not remarkable unless you look at the FPS. The RRC3 recorded the top speed at 3884fps which made the melted paint on the nosecone and forward sections of the fins that much cooler to look at.

Jason might have beat my height, but I've got him in belching and speed...
Click to expand...

Can you post or download your RRC3 data?
 
blackjack2564 said:
Stock Punisher I was referring to weighed 5 lbs. on the dot. [damn auto correct changed 5 to"a'' for some strange reason. Did it again here but i caught it]

Stability was 1.99 [2]

Actually , one I flew in contest was the sustainer for 2-stage. It has 1 lb. of nose weight, 2 altimeters, new MissleWorks GPS, 3-9v. add another .5 lbs. That's a lot of crap on a 2.5 x 5.5 sled.
Stability of 2.15
By the way GPS worked great for Alpha test!

Sims showed 13, 403 ft. Actual was 16,661.
All my sims for Punisher are WAY under. It's flown on motor as small as 3 grain 38 to 6xl 54 and stable on everything in between.
WaterMM you must have other issues if not getting altitude. Fins on straight? Altimeter off?

Jason used a tailcone in unlimited class, was stock other than that. I'm guessing he was at 5.25 lbs and beat me by 800 some ft.[17,400 something?] That was the tailcone. other flights showed the added weight paid off for this high trust type motor.
Hit 2432 ft/sec...um mach 2.1

Here's the first peek at MW GPS.....

View attachment 271608 View attachment 271609

Same screw hole pattern as RRC3 & .25in wider and .5 in longer if memory serves.

By the way, this thing IS the .50 bullet of rockets. It's scary stable in winds.
Click to expand...

Very cool CJ ! What engines ?

In our PunisheR drag race at ROCstock mine weighed 4.94 lbs without motor, was a NO paint rocket, but did have a tail cone retainer.

On a Pro54 6G K1440WT it went 15,178 ft .. had ComSpec tracker a Strato CF and a eGGtimer for electronics. Which blew away the sims.

Kenny
 
KenRico said:
Very cool CJ ! What engines ?

In our PunisheR drag race at ROCstock mine weighed 4.94 lbs without motor, was a NO paint rocket, but did have a tail cone retainer.

On a Pro54 6G K1440WT it went 15,178 ft .. had ComSpec tracker a Strato CF and a eGGtimer for electronics. Which blew away the sims.

Kenny
Click to expand...

L-935
 
bluerue said:
On Saturday at Airfest I got my punisher up to 15006 ft on an CTI L990, not remarkable unless you look at the FPS. The RRC3 recorded the top speed at 3884fps which made the melted paint on the nosecone and forward sections of the fins that much cooler to look at.

Jason might have beat my height, but I've got him in belching and speed...
Click to expand...

My barometer claimed over mach 3 on my L935 flight, but 1.6 was more realistic after smoothing the data.
 
bluerue said:
Jason might have beat my height, but I've got him in belching and speed...
Click to expand...

Hard to admit this, but we were BOTH out-belched by a girl!!!

My speed was Mach 2.09. What was yours again? Mach 3.48???? Can that even be real??

-Jason
 
Last edited:
I admit nothing Jason. Especially when it involves Amy.

I suspect the data needs scrubbed like a previous poster stated. But I did have melted paint on the leading edges. I used a high quality automotive clear coat too.
 
Either way, it was awesome!! It was great to meet you. Had fun and hope to hang out again next time.
 

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