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  #11  
Old 03-25-2016, 11:49 AM
Scud-B Scud-B is offline
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I have a set on order now as well.

As for the additional details (conduit, etc): Based on Space X's own marketing of the kits I suspect their intent was to provide something which would present a moderate challenge to construct, in order to teach several skills to the modeler, and a semi-scale model of their Falcon 9 seemed like the most logical vector. They use the motto "Build rockets, build engineers" so it seems to me that these are meant to be a teaching tool and a form of marketing. That would seem to be the reason that much of the detail is just printed on. Their Falcon 9 with Fairing is a large-ish model rocket with plenty of payload space and decent available engines choices. What a perfect way to get kids into rocketry, experimentation, and build some good will with the more technical public.

As it is, I couldn't live with the foam legs, the wooden ones were turning into a lot of work, and I really wanted to get this thing off the ground. If everything works out I might add some more scale details to mine but I'll be happy with the legsvand grid fins for the time being.
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  #12  
Old 03-25-2016, 12:45 PM
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blackshire blackshire is offline
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Quote:
Originally Posted by Scud-B
I have a set on order now as well.

As for the additional details (conduit, etc): Based on Space X's own marketing of the kits I suspect their intent was to provide something which would present a moderate challenge to construct, in order to teach several skills to the modeler, and a semi-scale model of their Falcon 9 seemed like the most logical vector. They use the motto "Build rockets, build engineers" so it seems to me that these are meant to be a teaching tool and a form of marketing. That would seem to be the reason that much of the detail is just printed on. Their Falcon 9 with Fairing is a large-ish model rocket with plenty of payload space and decent available engines choices. What a perfect way to get kids into rocketry, experimentation, and build some good will with the more technical public.
I hadn't thought of their kits in that way (I just saw them as promotional items, but excellent ones!), but what you say makes sense, particularly in connection with that motto of theirs. I would not be surprised if they keep account of kids (or perhaps even adults, especially younger ones) who might send them pictures and/or videos of Falcon 9 kits that they've made super-detailed, and/or modified to have additional functional features--SpaceX might maintain a "possible future employees list" comprising such people. (Clyde Tombaugh was hired by the Lowell Observatory to his great surprise, after he sent them drawings of Mars that he had made using his home-made telescope.)
Quote:
Originally Posted by Scud-B
As it is, I couldn't live with the foam legs, the wooden ones were turning into a lot of work, and I really wanted to get this thing off the ground. If everything works out I might add some more scale details to mine but I'll be happy with the legsvand grid fins for the time being.
I think you'll like Boyce Aerospace Hobbies' upgrade parts a lot. The legs' conformal fit is already quite good. All that's needed to make it perfect is to wrap a sheet of Testors sanding film (or sandpaper) around the body tube, then slide each landing leg up and down on it--and maybe a side-to-side a little bit, too--a few times until the two surfaces' curvatures match exactly. Also:

The Falcon 9 model could be flown finless by utilizing M. Dean Black's finless model rocket stabilization techniques (they're covered in this issue [see: http://www.apogeerockets.com/educat...wsletter379.pdf ] of Apogee Components' "Peak of Flight" newsletter), which use the motor's exhaust and inward-ducted air to stabilize the rockets. His stabilization methods also make launch rods unnecessary (hand-held, tube-launched distress signal flare rockets also use this method of stabilization). Below are links to some examples:

Here (see: http://www.cyber-heritage.co.uk/schermuly/mix1.jpg ) are several distress flare rockets (the unpainted metal cylinders) and their hand-held launching tubes, and here (see: http://www.cyber-heritage.co.uk/schermuly/pan2.jpg ) is another. In all of these flare rockets, the finless stabilization vents are readily visible at the rockets’ bottom ends. (Many of these flare rockets are 38 mm and 50 mm in diameter.) M. Dean Black’s finless scale model rockets use much smaller vents in order to preserve their scale appearance (the forward-mounted motor is part of such finless model rockets’ stabilization system). Plus:

These and many more photographs of life-saving (flare and line-pulling) rockets—as well as information on them—can be seen here http://www.cyber-heritage.co.uk/schermuly/ on the “Schermuly and his Rockets” website. Also shown on this site is a 2-inch diameter, fin-stabilized illuminating flare rocket (see: http://www.cyber-heritage.co.uk/schermuly/ilu.jpg ) that could be modeled using Estes parts!
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  #13  
Old 03-25-2016, 02:10 PM
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dwmzmm dwmzmm is offline
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Just got an e-mail that my Space - X parts order is on the way!
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  #14  
Old 03-25-2016, 02:18 PM
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Quote:
Originally Posted by dwmzmm
Just got an e-mail that my Space - X parts order is on the way!
They are very good about notification of coming shipments!
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  #15  
Old 03-26-2016, 10:58 AM
Scud-B Scud-B is offline
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This was made when they were offering the much different Falcon 9 with Dragon kit, but I think Space X's promotional video shows their line of thinking.

Space X Promotional Video
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  #16  
Old 03-27-2016, 12:19 AM
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blackshire blackshire is offline
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Quote:
Originally Posted by Scud-B
This was made when they were offering the much different Falcon 9 with Dragon kit, but I think Space X's promotional video shows their line of thinking.

Space X Promotional Video
Thank you--I'd seen it once a few years ago, and I agree with their motto (that was a perfect day, too--no swinging on the 'chutes!). Not every kid who builds and flies a Falcon 9 model will become an engineer or a technician in the field of astronautics (nor will those who do necessarily work at SpaceX), but among those who do work in astronautics, there is almost always some early inspiration that starts them on that path. (Even those who don't choose such career paths are more likely to be interested in and supportive of space exploration as adults if they fly model rockets as kids.) The pioneers such as Tsiolkovsky, Goddard, Oberth, and von Braun all found inspiration in Jules Verne's space travel novels (and von Braun also experimented with skyrockets as a boy), and many of today's space engineers, technicians, and astronauts (Jay Apt is an example) point to model rocketry as their inspiration.
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  #17  
Old 03-27-2016, 08:34 AM
frognbuff frognbuff is offline
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Quote:
Originally Posted by blackshire
You're welcome! I received my 3D printed parts today. The grid fins and landing legs look accurate and fit very well! I dry-fitted the whole rocket together (minus its clear plastic fins), and with the upgrade parts in place it looked just like the photograph on the kit box. Also:

Had Alex Boyce not mentioned to me that the grid fins’ airfoils are slightly thicker than scale, that small difference wouldn’t have been apparent. (Looking at them closely, I’m intrigued at their possibilities for use—as actual stabilizer fins—on scale models of the ballistic missiles, satellite launch vehicles, and guided missiles that use grid fins [I think they would stabilize such models just fine, particularly if those models were made to slightly larger scales].) As well:

If the Falcon 9 kit is built to depict one of the Falcon 9 V1.1 rounds that did *not* have grid fins and landing legs (Cassiope, Thales, etc.--for those missions, no first stage recovery was attempted because they required all of the first stage's impulse to get to the desired orbits), the "stock-built" kit is accurate. All that would be needed to depict one of these rounds would be to paint over the printed-on grid fins and landing leg alignment marks, leave off the self-adhesive sheet foam landing leg representations, and add an appropriate mission decal (if one was carried) to the payload fairing.


I already have an Aggressor Aerospace kit called the KZ-1 that uses grid fins for stabilization. This is a scale model of a Chinese SLV If you want one, I'll sell it to you wholesale.
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  #18  
Old 03-27-2016, 10:07 AM
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Quote:
Originally Posted by frognbuff
I already have an Aggressor Aerospace kit called the KZ-1 that uses grid fins for stabilization. This is a scale model of a Chinese SLV If you want one, I'll sell it to you wholesale.
I'm tapped out for this month, but that situation will change in a few days... Also:

I just read your description of the KZ-1 model's stability in Posting #1 here: http://forums.rocketshoppe.com/showthread.php?t=15323 , and I am intrigued. The fact that its grid fins work *at all* at that small size--especially considering how "rectangular bar-like" each "flat plate strip airfoil" is, as is apparent in a photo here (see: https://www.apogeerockets.com/Rocke...Rocket-Kits/KZ1 )--bodes well for the usefulness of grid fins on scale model rockets! (I'm not being critical of the KZ-1 kit--its grid fins' narrow-chord "flat plate strip airfoils" are hard to make to scale thickness at that size.) If the grid fins' "strip airfoils" could be made closer to their scale thickness, the turbulence that reduces the fins' effectiveness could be reduced. Maybe such a grid fin "master part" could be made, then be used to create cast polyurethane resin duplicates. If necessary for strength, fine chopped fibers could be mixed in with the resin before it was poured into the molds.
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  #19  
Old 03-27-2016, 02:59 PM
Scud-B Scud-B is offline
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I suspect the grid fins on that KZ-1 are acting more to create drag than in any other aerodymic way. They likely work in the same way that the skirts on many "finless" designs do, just moving the CP to the rear away from the CG. I could probably sort out some perfect-world physics for any effect they are having but I think the reality is that they are slightly more efficient versions of the same overall shape with solid surfaces. I wonder, given other aerodynamic considerations, how much air is actually moving through the grids of the scale model at flight speeds.

Hmmmmm...
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  #20  
Old 03-27-2016, 05:30 PM
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blackshire blackshire is offline
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Quote:
Originally Posted by Scud-B
I suspect the grid fins on that KZ-1 are acting more to create drag than in any other aerodymic way. They likely work in the same way that the skirts on many "finless" designs do, just moving the CP to the rear away from the CG. I could probably sort out some perfect-world physics for any effect they are having but I think the reality is that they are slightly more efficient versions of the same overall shape with solid surfaces. I wonder, given other aerodynamic considerations, how much air is actually moving through the grids of the scale model at flight speeds.

Hmmmmm...
That makes sense, since the model's grid fins' airfoils are really narrow flat plates, which are face-on to the airflow. (I'm not knocking the KZ-1 kit's quality; properly scale-proportioned grid fins are hard to make at its scale.) If the model's grid fins were swept back, it might exhibit more positive (faster-correcting) stability, as it would if swept-back solid plates (or a conical stabilizer) were fitted to the model instead. Also:

If the same model was fitted with scale-proportioned grid fins (whose "strip airfoils" were truly thin strips parallel to the airflow), and if it exhibited a lower level of stability (taking longer to respond--with less restoring force--to perturbing forces) than it has with its current grid fins, that would suggest that the narrow "flat plate strip airfoils" produce ineffective lift (because of the Reynolds Numbers at which such tiny airfoils operate, at the model's airspeeds). Another possible cause for such behavior, if such was observed, could be "choking" of the airflow that 'tried' to pass through the grid fins' airfoils, because they were so closely-spaced. (I think this would be a less likely cause, if such behavior occurred.) Determining the characteristics and capabilities of grid fins on model rockets would be an interesting NARAM R&D project...
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Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
http://www.lulu.com/content/paperba...an-form/8075185
http://www.lulu.com/product/cd/what...of-2%29/6122050
http://www.lulu.com/product/cd/what...of-2%29/6126511
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