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AfterBurners

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Well in my downtime building the 2.2 Snarky from Apogee I decided to sit and see if I can come up with a design for a 4" version. A true upscale would put the airframe(s) at 4.434 or close to 4.5" so I settled on a 4" version instead. The only thing with this design I have to work out is the exact size of the wings and stabilizers and nose cone. The sizes that are in this ROCKSIM file are exactly 2x the original kit.

Is there a formula to use to get the exact dimensions? What if you found the percentage difference between the two different sized airframes and decreased the wings and stabilizers by the amount, would that give an accurate scale size for a 4" model? Since I could not find a nose long enough (unless anyone knows where get one about 20" in length) I decided to go with balsa.

View attachment DynaStar_Snarky 4 inch.RKT
 

dixontj93060

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If you want to do an upscale that uses a 4" body dia. you multiply by 1.82 (4/2.2=1.82).
 

Flyfalcons

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Anything bigger than original is still a true upscale. It doesn't have to be 200% of original.
 

djs

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So.. are you going to fly the snarky on a sparky?
 

AfterBurners

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Just want to throw this out there...who or where can I get a 4" nose cone 20" in length or thereabouts???
 

AfterBurners

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Awesome that's exactly what I'm looking for. So we are on like Donkey Kong! Been tossing the idea of a 4" Skonkwulf as well.
 

RocketRev

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I built a four inch Snarky myself. Flew great till the last flight about a year ago with a CTI-38mm V-Max that snuffed out the delay column and came in as it went up, perfectly straight... right into the ground.

I also built it on RockSim but can't seem to find the design. But you apparently do not know yet that RockSim will do upscalework for you.

All you need to do is download the 2.2" version RockSim design into your RockSim program. Check your design files, the original Dynastar Snarky should already be there. Bring it up in RockSim. Slide over from File, past Edit, past View, to "rocket" and click on it. The last option on the bottom says "scale." Click on that and type in 1.818 which will then autoscale the whole design up to 3.9996" which is as close to 4 inch as you need. The fins, wings etcetera will all now be correct for a 4" version of a Snarky. You can print out the upscaled fin shapes and you're off to the races.

To adjust for a not quite scale lengthed nose cone, I have two suggestions.

A) Get a PML 4" nose cone. Its nice and pointy like the original 2.2 NC unless you're going fiberglass then there's other options.

B) After you choose the closest pointy NC, all you have to do is add length to the airframe in order to get the tip of the nose cone the proper distance from the aft end of your 4" Snarky. That's what I did and it looked Great..... until the great crunch took place.

Just remember to upscale the nose weight of the original design as well.

ENJOY!

Brad, the "Rocket Rev.," Wilson
 
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AfterBurners

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Brad - thanks for the great information. I will do that but on the wings and vertical stabilizer I'm going with the multiple piece design and using 1/4" balsa and hardwood around the leading and tips of all pieces. I'm also going to airfoil every piece. Going to go or at least considering ttw if possible? Gonna keep it lite and high. Giant Leap has the nose cone I want. 19.8" and 5.1. I think I get the nose cone there. It seem to be the closet to what I need. See link above in post #8
 
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RocketRev

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Brad - thanks for the great information. I will do that but on the wings and vertical stabilizer I'm going with the multiple piece design and using 1/4" balsa and hardwood around the leading and tips of all pieces. I'm also going to airfoil every piece. Going to go or at least considering ttw if possible? Gonna keep it lite and high. Giant Leap has the nose cone I want. 19.8" and 5.1. I think I get the nose cone there. It seem to be the closet to what I need. See link above in post #8
The upscale Snarky I built also uses the multiple piece design. I just took the drawings and cut them to the right shapes for making the fins. I also made them thru the wall and to the MMT for more strength. And I made mine out of 1/8" aircraft grade plywood with about 7 layers. Very strong and yet about eh same weight as the 1/4" balsa you're thinking of using. I only have to replace a few inches of the front of the airframe. I used LOC 4" tubing for my airframe, so its easy to fix. The original PML nose cone is also fine after the crash. Just needed a serious de-mudding.

I would personally rethink the 1/4" balsa and hardwood edges. It will be a ton of work for not much gain in weight loss. And 1/4" compaired to 1/8" is really going to increase your drag as well, though I suppose since its a Snarky, its already about as drag heavy a design as possible.

Brad
 

blackjack2564

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Here ya go Brad, bring back some memories? NSL Bong .

Maybe the close ups will help you AfterB.


100_2743.jpg 100_2744.jpg 100_2745.jpg
 

RocketRev

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Here ya go Brad, bring back some memories? NSL Bong .

Maybe the close ups will help you AfterB.
--------------------------------------------------------------------------------------------------------------
Hello Jim, I forgot you had taken those pics. They may be the only pics anybody took of my Snarky while it was still in pristine condition.

Thanks

Brad
 

AfterBurners

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Here ya go Brad, bring back some memories? NSL Bong .

Maybe the close ups will help you AfterB.
--------------------------------------------------------------------------------------------------------------
Hello Jim, I forgot you had taken those pics. They may be the only pics anybody took of my Snarky while it was still in pristine condition.

Thanks

Brad
Great looking rocket!! You did an outstanding job!
 

MaxQ

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I built a four inch Snarky myself. Flew great till the last flight about a year ago with a CTI-38mm V-Max that snuffed out the delay column and came in as it went up, perfectly straight... right into the ground.

I also built it on RockSim but can't seem to find the design. But you apparently do not know yet that RockSim will do upscalework for you.

All you need to do is download the 2.2" version RockSim design into your RockSim program. Check your design files, the original Dynastar Snarky should already be there. Bring it up in RockSim. Slide over from File, past Edit, past View, to "rocket" and click on it. The last option on the bottom says "scale." Click on that and type in 1.818 which will then autoscale the whole design up to 3.9996" which is as close to 4 inch as you need. The fins, wings etcetera will all now be correct for a 4" version of a Snarky. You can print out the upscaled fin shapes and you're off to the races.

To adjust for a not quite scale lengthed nose cone, I have two suggestions.

A) Get a PML 4" nose cone. Its nice and pointy like the original 2.2 NC unless you're going fiberglass then there's other options.

B) After you choose the closest pointy NC, all you have to do is add length to the airframe in order to get the tip of the nose cone the proper distance from the aft end of your 4" Snarky. That's what I did and it looked Great..... until the great crunch took place.

Just remember to upscale the nose weight of the original design as well.

ENJOY!

Brad, the "Rocket Rev.," Wilson
Hello Brad.
You know I've wanted to talk to you for quite awhile.
I was curious how many flights you had on that 4" snarky because I set mine asisde after hearing you had some issues with yours.
Perhaps not.

How much nose weight did you have to use, and how far inside the nose cone did you place it to get the CG where it was on the small version or was it even further forward?

BTW:
Loved your appearance on The Rocketry Challenge ......great segment.
 

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