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Help! Colonial Viper?

Good Project Build?

  • Not sure.

    Votes: 0 0.0%
  • To complicated. Don't try it.

    Votes: 0 0.0%

  • Total voters
    6
  • Poll closed .
#1
Okay. My inbox from Hobby King showed the "H-King 6-S Sky Sword". She's a 12-blade 70 mm EDF 990 mm (40") PNF. And being my age, (Cough-Cough) all I could think of was...
Has anyone ever built and flown a Tri-EDF Colonial Viper from Battlestar Galatica? Maybe tried differential thrust 3 ways? Guys? Gals? Anyone? 640px-Viper_Mk_II_orthos.jpg
 
#3
If Flite Test has shown me anything it's that just about anything can fly if you give it enough power and some sort of control surface.

My concern with the viper, as much as I would like to see that is the lack of wing/control surface area.

That being said, there is one way to find out, build it and try to fly it, and with that in mind I say go for it!
 
#7
I think you should try this but perhaps sneak up on it. Build a really light pusher version just to see how she handles and then maybe an EDF version and then go all in with the triple EDF.
Thanks Guys. Hey @DamoRC Here is the reason I know somehow this crazy thing will fly.
Colonial-Viper-Cutout.jpg
I don't have an operational printer right now. But I do remember this winging its way around the neighborhood. Anyone what to give it a go?
@Damos @TexMechsRobot @cranialrectosis @Mad_Mechanic @buzzbomb ?
 
#9
Thanks Guys. Hey @DamoRC Here is the reason I know somehow this crazy thing will fly.
View attachment 126463
I don't have an operational printer right now. But I do remember this winging its way around the neighborhood. Anyone what to give it a go?
@Damos @TexMechsRobot @cranialrectosis @Mad_Mechanic @buzzbomb ?
Heck, no! It's a space fighter with atmospheric wings, no thrusters for maneuvering in a vacuum and no wing surface for maneuvering in atmosphere. It's SciFi. I said it'd be cool to see it fly. No way I can pull it off! :p
 
#13
I think the key with this particular build would be getting the size/weight right. This is either going to have to be really big and floaty or extremely fast to stay in the air. Other than that, I think the aero is pretty sound for controlled flight.

My vote would be big and floaty unless you are confident in your thumbs.
 
#14
I think the key with this particular build would be getting the size/weight right. This is either going to have to be really big and floaty or extremely fast to stay in the air. Other than that, I think the aero is pretty sound for controlled flight.

My vote would be big and floaty unless you are confident in your thumbs.

I second big and floaty. Size it for a 2ft span , but I think it Will want to roll inverted .
 
#15
At this point, all points are relevant. Doing a pusher prop would be a quick into the air build. (After frying brain over fuselage). Now the other fun will be when the craft is Tri-EDF.
By original design the Mark I had reverse thrusters on the lower winglets and differential thrust from three engines, the lower two with a form of afterburners.
The Mark II added atmospheric control surfaces on the winglets and rudder plane, maneuvering thrusters in the nose and rear, afterburners on all 3 engines, and a inlet in the nose, plus a cooling vent in the new lower fuselage base that included skid style landing gear. The afterburner assemblies also included multi-vane vectored thrust plates.
In reading the faux details of this bird, she had enough power and maneuverability to kill it's pilot with extreme G-forces. Fun times all around! So, in building this bird I figure you go as simple as possible, use a vectored pusher prop, and may end up having to install a gyro unit to aid in over-riding to much control. Thus the slow large and floaty build.
 
#17
You bring up a great point. You would definitely have to keep all of the weight as low as possible. You might even have to drop the battery in a box below the fuse.
Hey, @Namactual Great point. I was just thinking because the CG needs to be low in the main Fuselage Mark II has a lower vented pod like structure between the two lower engines. Thinking this is were the ESC's and Batteries should live, the bottom as a door to move the Batteries and ESC's around to find the CG.

If I can get the Thrown flier cut out printed on two pieces of DTFB, grid W/out other stuff, put together and find it's CG, would that not give a good idea where the powered model would CG?

I'm also thinking the lower winglets might require a touch of UP trim to stabilize forward flight, or will the two lower engines along with one upper be able to trim power via electronically with the Transmitter settings, thus the top motor will never max out.

Maybe I need to build a Wind Tunnel big enough to test the big floaty bird in first. Safest way to test fly her.

And has anyone been able to configure a three way differential thrust set up? I know it is possible to cable three vectored thrust nozzles via the rudder and elevon controls, like a Kracken. But I've never seen anyone do 3.

Maybe that is the key here. Antihedral lower winglets, looks like 22.5 degrees down angle or less. I don't think its less than 11.25, but then I haven't been able to print any aft or forward facing pics to check it. The lower winglets should give some point or source of lift I'd think.
 
#18
Aye, you could make the lower air scoop a little bigger to get your battery as low as possible, I would lessen the amount of anhedral a bit as well. You could probably remove quite a bit and still look scale.

I also agree with the glide test being the best way to find your CG. You are going to have a lot of body lift so your CG is probably going to be a lot more forward than a usual guess.

As far a the uptrim, it will most certainly need it as it will only fly with a lot of AoA naturally. I would not try to fight it. Keep your wings planks, if you make them high lift airfoils your CG and CL will do crazy things at higher speeds.
 
#19
Aye, you could make the lower air scoop a little bigger to get your battery as low as possible, I would lessen the amount of anhedral a bit as well. You could probably remove quite a bit and still look scale.

I also agree with the glide test being the best way to find your CG. You are going to have a lot of body lift so your CG is probably going to be a lot more forward than a usual guess.

As far a the uptrim, it will most certainly need it as it will only fly with a lot of AoA naturally. I would not try to fight it. Keep your wings planks, if you make them high lift airfoils your CG and CL will do crazy things at higher speeds.
Nice pull @Namactual. I've downloaded this pic, and was thinking "Space Flight Control" versus "Atmospheric". 4-axisProfile.gif
With 1 pusher adding a dual horizontal and vertical thrust vector mount you can get "Pitch" and "Yaw" control assistance from the prop. But with 3 EDF's, things get a little... interesting.

Pitch downward comes from increasing power from the single upper engine, and thrust vectoring. Upward pitch with increasing the 2 lower engines power or thrust vectoring.

"Yaw" is met with Pitch added if you only use Differential thrust, and therefore takes more thrust vectoring into account.

"Roll" must be attained using eleron and possibly rudder to achieve. Unless you can program in three angle thrust vectoring to force Roll Spin from the 3 nozzles.

I can easily see where she'll want to fly upside down, and on her side would be... interesting to say the least. Pattern flying in competitions would take so-o-o-o many flight hours to get her to settle down into some semblance of balanced flight.
As mentioned previously large slow floaty, park flier might be the aim, but like the King Sword, She'd love to be a speedster.

Pusher versus EDF would end up being two different animals all together. She'll need three things I see to even think of making her flyable as an EDF machine. I'd suggest 12 blade high output EDF's. Thrust Vector nozzles a must. Thirdly, gyro stabilizer electronics. Shifting the batteries and ESC's into the cockpit floor would be another thing, hopefully shifting the CG into a usable point. She'll be tail heavy with the 3 control planes aft, as well as the engines.

Actually making this bird stay in the air is either the old "Throwing a bullet down range" style of flying, or the always interesting "Build, Crash, Learn, Build, Crash, Learn, Repeat" technique. Actually just putting 3 tubes with props in them, and adding a long tube nose, then 3 control surfaces and getting your head around getting that to stay in the air before making her look like an actual semblance of a Colonial Viper might be the trick.

Heck, I have even thought of controlling the winglets and rudder of the Mark I with internal driven servos driving landing gear wire through the thrust tubes, bent inside each control surface to move the whole plane of each independently.
 
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#20
I'm actually thinking of doing this. I found a mod for the FT arrow and am building a test bird for the cockpit. The next test is to pull off the Battlestar Galactica rebooted versions black bird. Then I'm going to feel comfortable with moving onto the mark 2 version. I feel like it'll have to have wings that have been embellished a tad so I plan on taking some creative license with the design.
 

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