Robotech VF-9 that flies, maybe Hovers,

[FoamyDM]

So I have just Arrived into the hobby and I am Eager to start my first scratch build.

this post is just The Mission statement:

Stage 1: Build the VF-9 from Robotech
I have always been in love with the forward sweeping plane designs. I may have started my career as a draftsman, however I have never designed an RC plane before. Here's a look at the goal:

SPECIFICATIONS:
Pusher
Length: 36"
Width: 36"
Wing Area: 200 in^2
Motor 2815 /09 1180kV
Propeller: 10x4.7
Est All up Weight = 750g
Wing Loading

PLANS:
Here are the plans:

This is missing the spars outlined in the main body. This is the first I have looked at them in over a year.

Maiden Flight:
I was supposed to be a Maiden Flight... but alas, just a taxi test.

Reserved

Stage 2:
Vectorized thrust is real now. Well sort of, I plan to accomplish this through a thrust Leg which drops down. to have a Hovering Hybrid mode. the goal is to have most of the controls in the center and ideally use 50-60mm EDFs with a flexible exit tube to redirect thrust. another idea is to have a way to open and close the thrust cowl/feet and the other is to bring down the thrust tubes via a cable system Much like the child droopy dog toy. I'm hoping a flight board with a Gyro will help this become a functional reality. if this works, the Zentrati better watch-out!

I have a LOT of work before Stage 2 is started. It's time to get started.

 

[planebreaker2000]

Exciting. Watching and good luck.

 

[Nerobro]

You're gonna have a heck of a time... Forward swept wings are what they call "divergent". That is, when you load them up, the bending loads on them causes them to deflect in a way that causes them to load themselves more, and that causes them to load themselves more. Until the structure fails.

Swept wings don't do that. Proper spar position on normal wings, prevents that as well.

.... I'm a Macross fan too. I was talking about what it would take to make something that could go from gerwalk to fighter a few weeks back. I think that's a reasonable goal, with some large ish ducted fans, and a VF-1 design.

 

[FoamyDM]

Education - Ideas

You're gonna have a heck of a time... Forward swept wings are what they call "divergent"....
...I was talking about what it would take to make something that could go from gerwalk to fighter a few weeks back. I think that's a reasonable goal, with some large ish ducted fans, and a VF-1 design.

Thank you for enlightening me to the issues of Swept wings and Divergent forces. I suppose we'll see.
I suspect I will use MESAFF Tomcat design and figure the legs out on that one. VF-1 style. Not out of scope, just off Scope.

I'm rolling around how many channels I might end up using in the transformation... I'll need a Gyro too... ah this is gonna be expensive, I can see it now. It'll be fun and time sucking.

-FoamyDM

 

[wilmracer]

Take a look at this thread on the X-29 parkjet. The forward swept wings at this scale can be made stiff enough that they generally don't have too much of the twisting issue. http://www.rcgroups.com/forums/showthread.php?t=1071404

I built one a while back and a gyro definitely helped with pitch sensitivity

Also take a look at this old thread over at RC groups. Similar subject: http://www.rcgroups.com/forums/showthread.php?t=1174936 Don't think it ever flew but could provide some interesting thoughts.

 

[Nerobro]

Take a look at this thread on the X-29 parkjet. The forward swept wings at this scale can be made stiff enough that they generally don't have too much of the twisting issue. http://www.rcgroups.com/forums/showthread.php?t=1071404

I built one a while back and a gyro definitely helped with pitch sensitivity

Also take a look at this old thread over at RC groups. Similar subject: http://www.rcgroups.com/forums/showthread.php?t=1174936 Don't think it ever flew but could provide some interesting thoughts.

That x-29 is "done right" I think a spar setup like that on the VF-9 would work...

The VF-9 might also be easier to handle inflight conversion. The VF-1 folds the tail to convert to gerwalk, and it's tail isn't setup to provide much pitch authority.

Hmmpf. Big thoughts here.. big thoughts.

 

[FoamyDM]

Nerobro and Wilmracer - took a look and I will use the X-29 wing stability configuration if I can. I'm not looking to use CFR so I'll see what comes of Foam spars and Hot Glue. I'd like to stick to FT construction methods; DTFB, skewers, popsicle sticks, zip-ties, coffee stirrers,etc. I'm still working out the upper vs. lower plane body in order to add strength and stability to the wings.

I'm working on the prototype plans:
View attachment 75092
and started building the prototype and have found the large nacell holes to destroy the wing to body strength. so I'm going to try and build cross sparring that will give the top form, overall frame rigidity. This will require me to split the nacells to top and bottom. Tops remain part of the main body, and bottoms separate and fold under. View attachment 75086

Question: With the Divergent forces on the wings my main concern is buckling the top of the spar and stretching the bottom right? just not sure how the biggest forces are coming. The X-29 at Parkjet doesn't have any wing shape, It's just a flat board.

I built the duct elbow portion with DTFB and it's TIGHT! I'm really excited about that... now to redo the the main body and fix the upper nacell, and close off the bottom. then split and Lower and attach the duct elbows. (pictures shortly)

 

[FoamyDM]

Another idea I was rolling around and not sure how to do it.
Controls in the other Gerwalk would use a whole other set of servos. Not to mention the servos used in the transformation... Which might mean some 12 channel transmitter I don't have. How can we get it down to 6 Channels?

Would a flight controller or multi-rotor control board solve this problem?

Right now I'm envisioning the following control scheme
Plane mode - Throttle runs the 2 edfs, (div throttle and rudder for rudder) and aelevonards control for Aelerons and Elevator and Canards (if Fixed wont work).
a switch activates the transfer. - This would remove the an internal flap that normally locks the Nacell in plane(horizontal) position. then would relax the servos from locked "up" state to a "Neutral" Gerwalk, like the floppy puppy push toy I had as a kid. and also spread the thrust cones.
Gerwalker: The servos that moved the legs down would control forward and back.This would also run pair of servos that tilt legs Left and right.(Aelerons) Rudders would then control Yaw. I think it's possible and a Flight controller with a "Hold Altitude" state could help.

I'll have to sketch it out. I'm not looking for something complex, but I know it will inherently be somewhat.

I'd love this on a 6-channel if possible so most flyers can try it?

What Say you Flite test Form? YAY or NAY?

 

[saiga556]

I have to agree with the majority here. Our wings are way over built, generally speaking. Many of our faster models are pulling Gs that a 1:1 plane never could. Don't let the forward sweep scare you.

 

[FoamyDM]

I've found my 3d work needs... work.
Some of the Nacell Matched up GREAT, and Some less so.
Pics of Progress on Prototype Build:

 

[Nerobro]

That looks really good. Don't get discouraged. I may want this more than you do

 

[FoamyDM]

Haha! That's so funny Nerobro.

It's cool to have another piloteer to share the excitement with.
I'm not dicouraged. Just realizing my mental 3d skills aren't experienced with plane builds yet. If anything, your enthusiasm is a big help.

 

[FoamyDM]

VF-9 Progress Update and More thoughts on Vector Thrust

Progress update:
I have use the X-29 spar idea and added a triangular flite-test style folded over spar system and tied/glued them into the wing spars. I have done a forward V-spar to support the foward body-wing form. This turned this from floppy to rigid. the wing tips deflect slightly when moved up and down which I take as a good sign. I think I will need to extend my aeleron control surfaces, as they barely extend beyond the bottom of the wing. the Belly bay is large enought to fit all the electronics and have room for an extra battery or OSD sensors, or bombs.

The Cockpit area has been framed out and ready for skinning (see Pics), I purposefully left lots of room for a camera in the cockpit proper. I love what I see but I wanted to build a simpler version too for release. I thought I might mock the cockpit controls up and put the camera on a swivel for best effect. Future considerations, having a battery in the cockpit belly for balance. It need a bigger pit, and I'm concerned about how the cockpit will do in a crash. I assume it will be destroyed, and I don't want a battery there. I'm going to slap some pushers at the lower nacel exits for testing until I can afford 2-64mm EDF units and the flight controller.

I have nearly finished the Plane enough to test it's fly-a-bility. so a chuck-glide test and determine CG just to see if it will fly as a plane (which is cool enough in my book) buy I would LOVE to get this to a stable Gerwalker form!

See the pics.

 

[FoamyDM]

Thrust Tubes

Vectored Thrust

So base on the models here, most thrust vectoring is a motor mounted to a plate controled by servos to change it's direction. Which I plant to use for my fly-a-bility testing. hover the final model should have EDFs which will use thrust tubes.

There are a number of successfull real-life methods. Like the tailless heli, using a thrust tube to remove the danger tail rotor. also the Harrier uses a baffle that directs thrust to rotating side tube that direct thrust down or back as needed.

The Harrier is the close, but no cigar, as I need something that will bend not just rotate, *thinks hard* ...unless I use a center engine and have two swivelling elbows at the top of the leg. I see three concerns with this.
LIST=1]
[*]The lost effeciency might be too much for the already servo heavy plane. Esp. in hover.
[*]How do I make lightweight duct tubes (other that some heavy pvc elbow?)
[*]It isn't keeping with the concept well enough. [/LIST]
Blast. oh well time to keep thinking.

So, this still leaves me with, "how to I bend the thrust tubes in a light-weight simple low-loss manner"

The F-35 Lightning II engine, the RR F-136, offers a Possible solution:
The sections rotate and turn the thrust tube nearly perpendicular. I hope to try this tonight, I just know rotated elipses never *really* line up. still trying to figure this out. Pic:


I can use the nested V-shaped ~20° elbow ducts I planned out. with the stops to limit movement and servos at each leg will run extension/push rods to extend and retract the legs and another servo to sway the legs inboard and outboard.

Either method should work, just how well is to be seen. This should be FUN!

If you have Ideas, improvements recommendations or criticisms, please comment below.

-Foamy DM

 

[FoamyDM]

It's taken me days to notice.

I have just see the bearing ring is a little larger than the resulting ellipse from the skew across the tube. as the angle is slight, the resulting ellipse is very close to a circle.,

How to accomplish this in a Foam/lightweight manner is harder. This is where a laser cutter would help.

 

[FoamyDM]

The work continues

I've been making steady progress. I'm nearly at the point I'll be adding servos.here's some more progress photos.




Hope you enjoy.
New AT10 radio link receiver came in and I'm still setting it up.

 

[FoamyDM]

Draft Control Scheme

Please look over and comment on my first draft of my control scheme. Comments are welcome.

 

[FoamyDM]

Cameras an Missiles

As I continue building this plane, working out lading gear, canard control arms, and figuring out how it will all get hooked up, I continue to dream.

I have a 3-way camera switch and associated cameras on their way in. I plan on having 1 in the cockpit (on a servo if possible), 1 on the wing looking in, and a third one. I was considering using it as a bomb bay camera. Then I saw this video:

https://www.youtube.com/watch?v=WFyKgmnCF-8

I wonder if I can do an under-wing camera instead and set a sidewinder launch cluster or four to view. just need to figure out a way to remote trigger. Right now I'm thinking 1 standoff with 3 posts and a rotating contact leading at the front of each match-head. when it rotates, it completes the circuit and ignites the missile. This will be fun to test. If it works it will be great on video.

-Foamy DM

 

[FoamyDM]

Stumped on Landing Gear

I'm working out the landing gear. I'm happy with the front, however I need the back to rotate from horizontal with the wheel flush to the underbody, to vertically aligned with the wheel oriented to the direction of flight. They need to rotate 90deg as they come down. I've got ideas, which I'll try, which seem too complex.

Can anyone provide guidance or ideas?

I want the landing gear in before I attach a pusher and test fly it.

 

[jamboree1]

I'd go for something very simple first, this plane is a very complicated design, I'd make sure it flies before going all out on details