Pem-Tech's Level 2 Build - "Certify With Us" program

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Pem Tech

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OK, the gray matter has started to smoke. WHat to build? What to build? What to build?
Sure, I supplied the requested list with the submission for this fantastic program, but I never even even hoped I would be selected. :blush:
Surprise, surprise...

So, now to call in the Tiger Team and lay out a plan. Personally, I am a low and slow guy, I want to see the whole flight. Just getting to watch a smoke trail in the distance never did anything for me. First it has to be low altitude. Secondly, keep it simple with single deploy and motor ejection. There will be a MAWD on board as a backup. Thirdly, it cannot suffer damage on landing. Fourthly, I have to KNOW that it will fly, so I'm sticking with proven layouts. Lastly, and most importantly, it has to fit my tastes. Get on back wit' dem' 3FNC's n' stuff.

After a LOT of pondering and rocksiming I think there is a candidate. But this may change if I run into any unforeseen problems in the early stages.

Ladies and Gentlepeoples, I present the upscale HMAS Bonestell!

L2 Bonestell P1017035.jpg

It will be 3.9" LOC tubing with a 3.9" PML NC, 76mm MM and four really big ballz. The 2.6" Bonestell is shown for scale.

Here is the RS file for your perusal.
View attachment Pem-Tech L2 Bonestell.rkt

Your input would be greatly appreciated, just don't laugh at the finlets. :no:

I could not get them orthogonal, no matter what I tried.
 
Huzzah!


Very much looking forward to this!



Later!

--Coop
 
I think this is gonna be sweet!!

That 76mm motor tube is REALLY going to be low and slow, Layne ;)
 
I think this is gonna be sweet!!

That 76mm motor tube is REALLY going to be low and slow, Layne ;)

Actually I was really surprised by the low altitudes from the 54mm motors like the J380-SS, only 1300 feet. The K575-SS sims out at 2400 feet.
But the sims are usually a bit conservative on this design, she isn't as draggy as RockSim thinks. So, I could fly a K530 and only hit a little over 2000 feet. (Guessing from previous flights.)
 
Good luck on this one.

I've thought it to be your coolest looking design ever since I build mine. Just don't let it end up like mine.
 
Good luck on this one.

I've thought it to be your coolest looking design ever since I build mine. Just don't let it end up like mine.


A moment of silence for Brother John's blowed-up Bonestell.......
Note to self, "No Go Boom"
 
Good luck on this one.

I've thought it to be your coolest looking design ever since I build mine. Just don't let it end up like mine.

I remember reading the news of its demise. Wish I could have seen her fly...


Later!

--Coop
 
Layne,
I notice that you used big, thick, square balsa fins to simulate the balls on the model. This makes the drag coefficient about 6. I took the liberty of adjusting the fins to be ellipical balsa nose cones mounted on pods instead of thick fins. This reduces the drag considerably, now to about 0.4. Instead of about 1000 feet on a J280SS it would be about 2780 feet. You have much more experience than me with these types of models and simulations. Just wanted to offer my simulation. I would hate to see you fly it for a level 2 cert expecting 1000 feet and it ejects too early, ripping the model apart. Here is the rocsim file:
 
There are probably a lot of rocketeers who would be interested in that.

Spotted this at grocery store and it made me chuckle...

My friends all housed a bottle of Kraken rum in honor of my King Kraken's completion.

It may have actually been coincidence, but whatever. It worked for them. Heh.


Later!

--Coop
 
Layne,
I notice that you used big, thick, square balsa fins to simulate the balls on the model. This makes the drag coefficient about 6. I took the liberty of adjusting the fins to be ellipical balsa nose cones mounted on pods instead of thick fins. This reduces the drag considerably, now to about 0.4. Instead of about 1000 feet on a J280SS it would be about 2780 feet. You have much more experience than me with these types of models and simulations. Just wanted to offer my simulation. I would hate to see you fly it for a level 2 cert expecting 1000 feet and it ejects too early, ripping the model apart. Here is the rocsim file:

Interesting. I did something similar: changed the blocks to BT 80 elliptical NC's, a short length of BT-80 tube, and a reducer/TC set to an ID of 0.01, and all comprised of Urathane or PVC (not knowing what the Ballz are made of, but they looked plastic, figured I'd err on the side of "heavy,") and got similar results.

But the Bonestell has flown before --in its smaller form. What Randy and I may be screwing with is an upscaled file that was previously modified to reflect observed data...


Later!

--Coop

View attachment Pem-Tech L2 Bonestell Modified Ballz.rkt
 
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Added wrong file before--corrected.


Later!

--Coop
 
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Interesting. I did something similar: changed the blocks to BT 80 elliptical NC's, a short length of BT-80 tube, and a reducer/TC set to an ID of 0.01, and all comprised of Urathane or PVC (not knowing what the Ballz are made of, but they looked plastic, figured I'd err on the side of "heavy,") and got similar results.

But the Bonestell has flown before --in its smaller form. What Randy and I may be screwing with is an upscaled file that was previously modified to reflect observed data...


Later!

--Coop

Layne,
I notice that you used big, thick, square balsa fins to simulate the balls on the model. This makes the drag coefficient about 6. I took the liberty of adjusting the fins to be ellipical balsa nose cones mounted on pods instead of thick fins. This reduces the drag considerably, now to about 0.4. Instead of about 1000 feet on a J280SS it would be about 2780 feet. You have much more experience than me with these types of models and simulations. Just wanted to offer my simulation. I would hate to see you fly it for a level 2 cert expecting 1000 feet and it ejects too early, ripping the model apart. Here is the rocsim file:


Both of you are correct, the square ballz were an expedient measure to get something going. The 2.6" Bonestell showed that the drag on the Ballz was much less than predicted, but still enough to be stable. A doubling of altitude would be fantastic! I'll run your sims and see if I can get away with a 54mm MM instead of the 76mm. Thanks to both of you for saving me the trouble of fighting with the d**n pods. They don't seem to like me. If you want to adjust your simulations the mass override on the Ballz is a direct measurement.

Yes, the Emperor Kraken was my first choice for L2 but it had been done quite successfully by several others.
Beware the Emperor Kraken, it is Coming...
It is Coming.....

Love the Kraken Rum! But I can't purchase it being in recovery, but I've asked a friend to get it, drink it and give me the bottle.

Thanks to everyone for your support!!
 
My congrats also on being picked for cert program!

Your pick for the build is "Lamalicious". Good luck with your attempt.
 
My congrats also on being picked for cert program!

Your pick for the build is "Lamalicious". Good luck with your attempt.

Lamalicious.....
OOhhh, I like that too!

OK, Coop and Randy caught me half baking it....
Went back to the 2.6" Bonetsell and copied the Ballz technique to the Upscale. We now have four plastic ballz of correct profile and mass, but now she want to rip off to 5000 on a J380SS. Time to add more drag.

And How did you fix my finlets???
They are now orthogonal to the wings like they should be.
 
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And How did you fix my finlets???
They are no orthogonal to the wings like they should be.

I just fiddled around with the radial positioning of both the pod and the finlet until it looked right...

Heheh. More drag? Easy! Up the airframe size!

(Moi? Bad influence? Pshaw....)


Later!

--Coop
 
I just fiddled around with the radial positioning of both the pod and the finlet until it looked right...

Heheh. More drag? Easy! Up the airframe size!

(Moi? Bad influence? Pshaw....)


Later!

--Coop

Thought about that, but then my Ballz would be too small.
:grin:

OK, think I may have a motor picked out. With the addition of a aft ring and half rings dorsal and ventral I think I could get away with this one:
(After consideration a smokey would be a safer choice than a Skid if the weather is dry)
Cesaroni J280-SS

Smokey sam
https://www.thrustcurve.org/simfilesearch.jsp?id=1412

My RS doesn't have the eng file for this motor. ANybody want to share?
 
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My favorite of the CTI/Certify group offerings. This is going to be fun to follow along.

Congrats Layne, and good luck with the cert flight!

s6
 
Those be some big ballz!:eyepop:

Ever gonna release the Bonestall kit or was I under a rock when you did?

Anyway,congrats on you being picked for the Certify With Us program!:clap:

Now, go let those Gnomes out of those boxes!


:roll:
 
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