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#1 haiduk Jan 13, 2013 02:38 PM

Snickersnee design and build
 
16 Attachment(s)
Santa left us a new machine under the tree. A 40watt CO2 laser cutter! Our CnC router has a new cousin to keep it company in the shop. After setting it up we've done a few tests and it works wonderfully. The laser has more cutting power than I expected. Now I just need to design up a new plane to cut with the new laser cutter.

Back in the day, my dad designed a slow-combat control line that he called the Snickersnee. In his honor I want to design, laser cut, and build a 400 sized electric stick for r/c streamer combat. Since this will be a stick type design, I'm going with a variation of the third definition here:
snickˇerˇsnee (snhttp://img.tfd.com/hm/GIF/ibreve.gifkhttp://img.tfd.com/hm/GIF/prime.gifhttp://img.tfd.com/hm/GIF/schwa.gifr-snhttp://img.tfd.com/hm/GIF/emacr.gifhttp://img.tfd.com/hm/GIF/lprime.gif)
n.
1. A knife resembling a sword.
2.
Archaic The act of fighting with knives.
3. To Stick or Snee.

Pops original Snickersnee design was characterized by its diamond shaped wing tips and sharp corners. The slow-combat control line model looked very similar to this model I set up for the RealFlight simulator a while back:
http://www.knifeedge.com/forums/down...5884_thumb.jpg
My design process usually starts by drafting a simple scale drawing to import into 3DS Max so I can generate a 3D model for design testing in RealFlight. Once I'm happy with the shape and size of the flight surfaces and the handling in the sim I start designing the structure.

I will be keeping notes and documenting my design and build process in this thread...

EDIT (20Jan2013):
- added the prototype and streamer cut 3d models to the RealFlight Swap Pages
- StickerSnee_EA
- StickerSnee (streamer cut)_AV

EDIT (15Apr2013):
- added link to Haiduk Aeromodels
- posted full size PDF plans on www.haidukaero.com


NoStep's Maiden Flights:
NoStep SnickerSnee Maiden 4-22-2013 (5 min 57 sec)


First SnickerSnee combat NoStep vs. Haiduk:
P1060594 (6 min 0 sec)

#2 maxxnut Jan 13, 2013 03:07 PM

I will be dropping by for a visit...with proper notice of course.

#3 dz1sfb Jan 13, 2013 03:27 PM

Duk,

Would you mind sharing what this laser setup costs? Santa might have to make a mid season delivery.

Ken :)

#4 haiduk Jan 13, 2013 04:02 PM

5th Generation Full Spectrum Laser
 
This laser setup is from Full Spectrum Laser. The laser unit has a base price of $3500, but you will also need a dry air compressor, a water pump (in a bucket of distilled water) for cooling, a filtering device, and a computer to drive it. It is quite an investment, but FSLaser does have a lower cost model that's under $2k as well.

5th Generation Full Spectrum Laser - base $3500
40W Basic Hobby Laser - base $1850

#5 haiduk Jan 13, 2013 06:11 PM

3DS work - wings
 
7 Attachment(s)
RealFlight requires the wings of the model to have a left and a right main wing panel as well as a left and right aileron. They will also have to be set up with a specific hierarchy. More about that later.

#6 Freddie B Jan 13, 2013 09:19 PM

Looking awsome already. The lazer is the bomb, congratulations. I'm now subscribed... ;). I'll be watching and wishing the best on a short learning curve. When you get some time on the lazer it would be interesting to know what the cost of run time is on the machine is at, per hour say. :D

Thank you for sharing your great new machine and process.

Fred :)

#7 haiduk Jan 13, 2013 09:57 PM

3 Attachment(s)
Hey thanks Fred. I think a replacement laser tube is around $350. They say they last about 1,250-1,500 hours on average. Time will tell.

I did get some work done shaping the fuselage on the 3d model. Hopefully, I'll get some more work done tomorrow.

#8 No Step Jan 14, 2013 01:48 AM

Very cool! The ultimate tool for the discriminating scratch builder. This will be fun to watch. Good luck with it.

Fred

#9 madbomber Jan 14, 2013 07:51 AM

What software are you using to make the 3D model?

Also, subbed.

#10 haiduk Jan 14, 2013 12:51 PM

Modelling the Outrunner
 
4 Attachment(s)
I'm using Autodesk 3ds Max 2010 to create the 3d model for RealFlight.

I took my drawings of a 400 sized outrunner (2830) that I am planning on using with this airplane and imported them into 3dsMax. I used a "Lathe" operation to make the motor parts and extruded the X-mount. Looks fairly convincing for a low-poly count 3d model.

All of the 3d images I've rendered so far have no textures mapped. They are still just basic random colors. I'll document the setting up of the texture map for color scheme after I get all of the 3d parts modeled.

#11 maxxnut Jan 14, 2013 01:21 PM

I think the fin should be a little taller

#12 haiduk Jan 14, 2013 04:25 PM

1 Attachment(s)
I checked the area of the vertical stabilizer and it does seem a bit small at 9.5% of main wing area. Currently it's 5" tall. If I scale up the fin so it's a half-inch taller, the area of the fin would be boosted by a couple percent. More fin area will definitely help the bird track through corners with less adverse yaw.

We're still looking at the lines from a cosmetic point of view. I will know more about the flight characteristics with different sized flight surfaces while tweaking the flight model in RealFlight. This is just a basic initial model for verifying these things before committing to a final shape and before designing the parts of the structure.

Think it needs more than 11.5% total area?
Does it look better larger?

#13 kenh3497 Jan 14, 2013 04:40 PM

[QUOTE=haiduk;23814360

Think it needs more than 11.5% total area?
Does it look better larger?[/QUOTE]

Looks wise, it looks good in either size. So... I would make it the larger size. The only thing to look out for is the shift rearward of the CG. That may not be an issue though.

Ken

#14 Freddie B Jan 14, 2013 06:00 PM

Duk,

Many variables affect things like the vertical fin area. If you have a moment measured from the trailing edge to the hinge line on the horizontal of 1.8x to 2.4x the cord, you should have 13% area of the wing. Height is often derrived by similar formulas to get a fairly good 'look' to a design.

I have a great 2-3 page standard moments and area caculations sheet (from a book that probably dates back 50-60 years), but works out everytime. It was designed by model builders, for model builders and is quite simple to apply. If you want I can either scan and post here, email, or even snail mail you a copy, just let me know.

Fred :)

#15 haiduk Jan 14, 2013 07:09 PM

Quote:

Originally Posted by Freddie B (Post 23815355)
Duk,
...
I have a great 2-3 page standard moments and area caculations sheet (from a book that probably dates back 50-60 years), but works out everytime. It was designed by model builders, for model builders and is quite simple to apply. If you want I can either scan and post here, email, or even snail mail you a copy, just let me know

Fred, if you could scan and post that document, I would be grateful. Sounds like it would help out a lot.

I measured the moments to the hinge lines of the tail-feathers. The basic wing (without the ailerons) has a 7.5" chord. The distance between the aileron hinge line and tail hinge lines is 16.2". If I calculated it correctly, that would give a moment of 2.16.

Sounds like I should bump up the vertical fin to 13% of the wing area. Let me see what it looks like.


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