Combat Wing for Flite Fest 2022

[Pieliker96]

Well I've always wanted to make a plane specifically for combat, and now seems to be as good a time as ever. I'll be using parts I have laying around to save cost and aiming to make a plane which is durable, defensive in design, and has offensive capability.

Hardware:
Flitetest Power Pack C on a 9x6 or 9x9
Two Emax ES09MDIIs
Two 2250 4s batteries in parallel
20"x1" carbon-fiber tube spar: and offcut from the XB-70 project

Design Choices:
A flying wing design for its mechanical and aerodynamic simplicity while providing minimal snag points during collisions
Prop-in-slot to move the prop to where it is least vulnerable in collisions, at the expense of efficiency
Control surfaces in the propwash to provide enhanced control authority, especially at low airspeeds
A camera mount to catch the action from the air
Skids or deflectors will be used to protect servo linkages, the camera, and minimize scratches on belly-landings
An opponent snag-and-drop system, similar to that in this reddit post: The line will be deployed on takeoff and held to my plane by a friction-fit parachute. When it snags another plane, the parachute will pull out of my plane and either slow the descent of or inhibit the flight of the plane it attaches to. I have successfully snagged other planes with a line back at FF21, though my plane at the time was a little bitty profile 3d plane - I ended up getting dragged around by my opponent instead of bringing them down!

Design Goals:
A TWR of around 1 (preferably greater) would ease launching
10 minutes of flight time in cruise would ensure I make it decently close to the end
The plane in general should be mechanically strong - more, thicker structure
The leading edges and nose should be especially stout, to take an impact


Some of the components, including a ~22" diameter Estes parachute.

 

[Crow929]

"minimize scratches on belly-landings"

 

[Merv]

...An opponent snag-and-drop system, similar to that in this reddit post: ...

FF combat has 2 rules.
1 - Be safe
2 - Hit the other guy before he hits you

I’m not sure a fishhook being towed by a plane satisfies either rule.
I’d recommend against that idea.

 

[Piotrsko]

Actually which style of combat: streamered or non streamered? I would bet streamered. Whole different series of planning decisions which may not include survivable aircraft.
Prop in slot is nice until something gets into the slot, and it wont cut streamers.
Whole series of combat threads here on site, go find them and do a bit of study

Finally: bigger is always better but there are limirts to how big.

 

[Merv]

...I would bet streamered...

No, very few streamers will be used. It full collision combat. Last one flying wins the bragging rights.
When it’s over, it looks& like someone planted a bunch of airplanes.

 

[Pieliker96]

FF combat has 2 rules.
1 - Be safe
2 - Hit the other guy before he hits you

I’m not sure a fishhook being towed by a plane satisfies either rule.
I’d recommend against that idea.

I can understand if you think it's a bit against the spirit of the event - though I have seen planes go into combat with streamers, with the intention to disarm the opponent. I have some trouble understanding exactly why it's unsafe. The system is designed to slow the descent of or massively increase the drag of the target aircraft - far slower and manageable a phenomena than trying to fly a wingless or otherwise uncontrollable plane after a hard impact.

Actually which style of combat: streamered or non streamered? I would bet streamered. Whole different series of planning decisions which may not include survivable aircraft.
Prop in slot is nice until something gets into the slot, and it wont cut streamers.
Whole series of combat threads here on site, go find them and do a bit of study

Finally: bigger is always better but there are limirts to how big.

If I remember correctly there is a streamer combat event which I do intend to participate in. Prop-in-slot would certainly be at a disadvantage here due to tanglement concerns, but I'm still gonna send it!

Here's some build photos:


And of course, feature creep got the best of me - I made it a night flyer while the upper skin was still off. Some 5v USB LED tape from the hardware store and a 10A bec along with a hand-soldered color selector for each wing make it look real nice in the dark.


On the first flight, the CG was too far forwards and I vastly underestimated the reflex needed to get it to fly: After a couple failed VTOL attempts (not quite enough TWR, and/or not enough thrust angle) I was able to get it in the air - though with all of my up-trim and holding a good bit of back-elevator. For the second flight I moved the CG back and added reflex to both the elevons and center section behind the prop.

Pitch was somewhat sluggish and roll was really sensitive, leading to the somewhat sketchy takeoff. I've added a launch-assist uptrim switch and changed the elev/ail expos from 40%/40% to 20%/60% to compensate.

With the current setup (PPC, 9x6R, 2x2200 4s) I was able to get 17 minutes of flight time by not flying like a maniac and running the batts down to 3.5v/cell. This vastly exceeded my expectations, I expect to be able to fly the full duration of the combat event, should it survive that long.

Total weight with the batts and a gopro is currently at 1300g. Wingspan is 40", Wing area is 460in^2, resulting in a cube loading of 8. With a measured 1700g of static thrust, the static TWR is 1.3.

I've still got to add the combat-specific modifications: foam fairings over the servos, pushrods, and control horns, as well as the tube for the chute.

 

[Merv]

...I have some trouble understanding exactly why it's unsafe....

Maybe I don’t understand what you are attempting but the thought of a plane towing a treble fishing hook just doesn’t sound good to me.

 

[Pieliker96]

Maybe I don’t understand what you are attempting but the thought of a plane towing a treble fishing hook just doesn’t sound good to me.

Oh heavens no it won't be a fishing hook - that would be an absolutely terrible idea. (I didn't even see the hook in the original reddit post - I was too focused on the chute system!) It'll likely end up with a small foamboard drogue at the end of the line, possibly recurved to snag easier - or just the bare line itself. It'll look something similar to this setup I did on my Otter last year, just with the line attached to the chute.

 

[Pieliker96]

Linkage covers, chute tube, chute, line, and drogue installed

 

[Mutley]

I am happy to find this post! Towing a slotted body behind you with thick cotton string is deadly to other aircraft in combat. I took out like 2 planes just from my passive string and 2d foam board missile in tow last year. congrats on the build.

 

[Pieliker96]

More "hook"-ier hook installed, along with a servo release for the line

 

[Pieliker96]

Servo/ linkage covers doing their job

Haven't got a snag with the drogue yet, the new design was aerodynamically unstable and yoinked the chute prematurely

 

[Test Fly RC]

Servo/ linkage covers doing their job

View attachment 227538
View attachment 227539

Haven't got a snag with the drogue yet, the new design was aerodynamically unstable and yoinked the chute prematurely

It looks like the damage, that bloody wonder gave your plane, is repairable.

FF combats are fun, even if you have to repair your planes a little.
Keep having a great time, the weather there looks beautiful!

 

[Pieliker96]

It looks like the damage, that bloody wonder gave your plane, is repairable.

FF combats are fun, even if you have to repair your planes a little.
Keep having a great time, the weather there looks beautiful!

Most certainly. I nosed it in due to ESC BEC failure in the first combat and clipped the Flerken banner by request in the second - At this point I'll be surprised if it doesn't need repairs between flights!

 

[Pieliker96]

 

[Mutley]

 

[Mutley]

Strings work in combat. That's Bixler winding up my string from last year's FF.