Lakeroadster's X-Wing Alpha Build Thread

[KSoldier]

There are lots of different ways to make this style of ship. I found this a while back and is very similar to your design. Nice work!

 

[GlenP]

There are lots of different ways to make this style of ship. I found this a while back and is very similar to your design. Nice work!

There are a couple of threads on that Centuri Design Contest X Wing model floating around here. I modified it to make a New Resistance X-Wing, slightly different wing and engine intake shapes, a little orange dot decal represents BB-8. Cardstock nose cone came from an X-wing paper model I found on the web. The main body tube is a paper towel roll, all other tubes were rolled from cardstock. Centerline launch lug holds a nose gear for horizontal display, like the old Centuri Buck Rogers Starfighter kit.

https://www.rocketryforum.com/threads/centuri-design-contest-x-wing-fighter.33071/

X-Wing Goonie:
https://www.rocketryforum.com/threads/x-wing-gone-goonie.110331/

 

[lakeroadster]

There are a couple of threads on that Centuri Design Contest X Wing model floating around here. I modified it to make a New Resistance X-Wing, slightly different wing and engine intake shapes, a little orange dot decal represents BB-8. Cardstock nose cone came from an X-wing paper model I found on the web. The main body tube is a paper towel roll, all other tubes were rolled from cardstock. Centerline launch lug holds a nose gear for horizontal display, like the old Centuri Buck Rogers Starfighter kit.

https://www.rocketryforum.com/threads/centuri-design-contest-x-wing-fighter.33071/

X-Wing Goonie:
https://www.rocketryforum.com/threads/x-wing-gone-goonie.110331/#post-1265298

It's the X-Wing Cyrano de Bergerac Version!

 

[lakeroadster]

Broom handle glamour shoot...

 

[BABAR]

Still hoping for a pad shot and a flight reports!

 

[lakeroadster]

 

[Crawf56]

Well done...............rebel scum.

 

[BABAR]

Awesome!

Light that candle!

 

[neil_w]

I hereby dub @lakeroadster "King of Swing".

One thing you're allegedly supposed to do when swing testing: tie the string slightly behind CG so the rocket hangs at about a 10-20 degree downward angle (can't remember the number). Therefore you test stability at an angle of attack the rocket might see in flight. Couldn't tell if you were doing that.

Disclaimer: I have never done a swing test in my life.

 

[Ted Cochran]

One thing you're allegedly supposed to do when swing testing: tie the string slightly behind CG so the rocket hangs at about a 10-20 degree downward angle (can't remember the number). Therefore you test stability at an angle of attack the rocket might see in flight. Couldn't tell if you were doing that.

Also remember that since the rocket is being swung in a circle, it is always seeing an angle of attack inversely proportional to the diameter of the circle.

 

[cbwho]

Awesome army X Wing, worth a thread bump!

You folks that have used Open Rocket.. you pretty comfortable with the actual in-field comparisons of simulations vs actual flights?

I dropped the vertical stabilizers, optimized the ballast and the rocket is still stable. maybe because of the faux engine pods that act as tube fins?

Thanks in advance.
View attachment 342916

I did a little experimenting with open rocket, if you take the angle of the X Wing to be zero degrees i.e. 2 fins overlapping, O.R. said it was stable. So I think it ignores the exact cruciform arrangement. When I built my X Wing inspiration, I simply had the CG balance ahead of the fins as per Apogee's safety rules https://www.apogeerockets.com/Peak-of-Flight/Newsletter501

The real question is how sharp of an X can we go? If we don't have the vertical fins and engine pods?
The Apogee newsletter hints the fins need to stick out 1.5 calibers. Another check could be the cut out silhouette method. So it would be dependent on the angle be greater than 0 and long enough to stick out about 1.5 in silhouette?

Our Dragonfly is very stable, it actually starts to backslide at apogee. We get almost zero rotation as well, which makes for a great camera platform.

Our fins are in a 60/120 degree spacing, yours look to be a bit closer/farther spaced. One nice thing about the X-Wing design is that it allows the Dragonfly to fit through a 30"door, even with our 60" span.

In case you want to see the rocket:



More onboard video from a different launch:

I also noticed this strange amount of stability of my X wing inspiration! I launched mine in windy conditions today and was amazed.

I went with 45/135 degree spacing and additional tube fins (jet/space engines).


One more question: "installed the Launch Lugs. They needed to be fairly long to cover the variation of CG due to different engine configurations. "

I tend to attach my lugs on a fin root, why is it so important to have on CG? Never noticed a difference...

 

[Cape Byron]

I hereby dub @lakeroadster "King of Swing".

Not the Sultan?

 

[neil_w]

Not the Sultan?

Taken.

 

[lakeroadster]

Awesome army X Wing, worth a thread bump!

One more question: "installed the Launch Lugs. They needed to be fairly long to cover the variation of CG due to different engine configurations. "

I tend to attach my lugs on a fin root, why is it so important to have on CG? Never noticed a difference...

Thanks..

Launch lug near cg tends to prevent the rocket from cocking and getting stuck on the launch rod....

That's my story and I'm sticking to it..

 

[lakeroadster]

Taken.

Genius... I'll try to remember to use Dire Straits music when I do the next swing test video...

 

[BABAR]

I wanna see it launch!

 

[lakeroadster]

I wanna see it launch!

Me too...

 

[Daddyisabar]

Had a great time launching with the Longmont rocket club yesterday. Just 3 top men and one top lady out having fun. Put up the Shinden. BLACKBURN TRIPLANE and the X 30 (one of the worst kits ever) on a D10! I think SCORE is still a go for next week. Great outdoor fun. All the nerds have been social distancing for years so no problem there! Oddrocs still get the Far Far Away pad.

 

[lakeroadster]

Between painting bedrooms ..... I created a "Build Video".

(Thanks to @neal_w for the inspiration.)

 

[lakeroadster]

 

[lakeroadster]

I spent some time updating the X-Wing Alpha to OR 22.02.beta.01. I tried to make it as accurate as possible, even including all the bits and pieces inside the motor pods which were beyond the scope of OR15.

On a D12-5:

OR15 shows a stability of 1.0 and an apogee of 1029 feet​

OR22 shows a stability of 0.665 and an apogee of 806 feet​

On a C6-5:

OR15 shows a stability of 1.26 and an apogee of 598 feet​

OR22 shows a stability of 0.98 and an apogee of 506 feet​

​

The swing test I did on a D12-5 indicates the rocket is stable.
Guess I need to buy an altimeter... so I can get a feel for accuracy, sim vs reality?

 

[lakeroadster]

Watch your six, Luke!

More OR 22 Updates... this one the X-Wing with the TIE Fighter Booster. It's unstable... but it's a starting point.

 

[lakeroadster]

Ain't pods fun?!
I'm both scared and curious to see how the children come out.

If you're open to potentially helpful suggestions, read on. If you want to do it all on your own, move on to the next post.

With the X-wing's wings so far forward of the tie fighter it's no wonder stability is a problem. Shortening the connecting tube might help, so the two stages' fins are not so far apart.

The X-wing's body forward of the fins looks right to me, which probably means it's too short. Every time I see an accurate model side on I'm surprised all over again at how long that thing is. Unless, of course, you've found scale drawings and used them, which wouldn't surprise me a bit. The astro-mech's compartment is conspicuous by its absence, and lengthening the tube by enough to fit that in between the fins and the cockpit would help.

Last, I think the nose cone is too short, and lengthening that would also help stability.
----------------
Uh, well, I found this, which indicates that most of the above is garbage. You still should, IMO, shorten the connecting tube by at three quarters. The dorsal and ventral fins, which are additions of yours no doubt because they're totally necessary, could be moved all the way back to the base the X-wing, which would help stability a little, but very little since it would help on one axis but not the one that's the problem. It would make room for a greeble dome for the astro-mech, which belongs between the wings according to the linked drawing, contrary to what I wrote above.

Since you've made one concession for the sake of stability (the ventral and dorsal fins) I guess you might make another by lengthening the X-wing even though I was wrong above. If it were mine, I'd try taking out three quarters of the connecting tube, then adding half of what's removed to the front of the X-wing's body and the other half to the nose cone.

Awesome link Joe... thanks for posting that.

Such is the challenge. Engineering away from massive scale alterations that result in a model that no longer appears like the movie versions.

Estes didn't always do that. Their models often looked good until adding modifications for a stable flight configuration.. then it's like "Hey Timmy, what the hell is that thing supposed to be?"

Allow me to enter into evidence Exhibit One.

Our victim, a Mr. D. Vader, a handicapped adult male from D. Star Arizona. Mr. Vader was killed instantly. He was unable to see anything due to the dangerous and careless addition of the lengthy tubular protrusion, added by the defendant Vern Estes and his accomplices at Estes Industries.

If I may site precedence: A Mr. R. Bobby was awarded 10.5 million dollars in the year 2006 from the Nabisco Corporation for a similar incident, where a huge "Fig Newtons" sticker was placed across the windshield of his NASCAR vehicle, blocking his vision.

​

Just kidding...

I changed the material of the X-Wing nose cone from balsa to polycarbonate. It's now marginally stable. I can turn a new nose cone from some composite decking material I have on hand... that stuff is heavy.

Some additional tweeking should get the stability up to a more comfortable margin... and the swing test will confirm stability. The Tie Fighter isn't very aerodynamic, so with that much base drag my mindsim tells me it'll be more stable than the OR simulation states it is.



Worst case scenario..

 

[GlenP]

The Tie Fighter isn't very aerodynamic, so with that much base drag my mindsim tells me it'll be more stable than the OR simulation states it is.

That is true if the Tie Fighter were flying by itself, but if you look at a front view, a significant portion of the Tie Fighter is in the wake and the base-drag shadow of the X-Wing. You only get an incremental amount of base drag from the portions of the Tie Fighter that protrude beyond the frontal shadow of the X-Wing. The Tie FIghter is drafting behind the X_Wing so this actually reduces the drag quite a bit, like race cars and cyclists often do. You could slightly increase the size of the Tie Fighter body and/or panels so that they become more effective and extend into the air stream beyond the wake of the X-Wing, maybe? Actually the Tie panels are probably pretty effective where they are, but the body base drag might not be as much as you think when drafting behind the X-Wing. Your swing test will demonstrate for certain though.

 

[lakeroadster]

That is true if the Tie Fighter were flying by itself, but if you look at a front view, a significant portion of the Tie Fighter is in the wake and the base-drag shadow of the X-Wing. You only get an incremental amount of base drag from the portions of the Tie Fighter that protrude beyond the frontal shadow of the X-Wing. The Tie FIghter is drafting behind the X_Wing so this actually reduces the drag quite a bit, like race cars and cyclists often do. You could slightly increase the size of the Tie Fighter body and/or panels so that they become more effective and extend into the air stream beyond the wake of the X-Wing, maybe? Actually the Tie panels are probably pretty effective where they are, but the body base drag might not be as much as you think when drafting behind the X-Wing. Your swing test will demonstrate for certain though.

Agreed.

I have a "scale" TIE Fighter CAD model I created. I need to dimension it and then update the Open Rocket model. The sim at this point was just to see if further modeling is worth the effort. It appears it is.

 

[jqavins]

If I may, and just one time more, I'll raise again the question of the linking tube length. Why did you make it so long? It still looks to me like shortening it is likely to move the C_P aft by more than it moves the C_G. Have you tried fiddling with that length? Am I wrong about its effect?

 

[lakeroadster]

If I may, and just one time more, I'll raise again the question of the linking tube length. Why did you make it so long? It still looks to me like shortening it is likely to move the C_P aft by more than it moves the C_G. Have you tried fiddling with that length? Am I wrong about its effect?

It helps, but a negligible amount.

With a 6" long tube my revised simulation shows a stability of 0.029
With a 3" long tube, the stability is 0.074

The entire "look" of this rocket is based on the appearance of a dog fight between the TIE fighter and the X-Wing. Anything less than 6"and it looks more like a Kamikaze attack.

A classic case of form over function.



Nose weight brings the stability of this rocket into compliance.... so the swing test will tell me how much is really needed.

 

[Tobor]

Maybe try rolling the X-Wing 45°~90° on it's longitudinal axis, like the X-Wing was performing a barrel-roll as a defensive maneuver.

Edit: Better yet, use a slinky between the two fighters to create some dynamic movement during flight....

 

[jqavins]

Y'know, I totally didn't get the dog fight part. I just saw silliness in cramming an X-wing and a tie fighter together. Thus my silly quip about the children. It was even you who wrote "Watch your six, Luke", and I still just saw silliness.

This is Thicky McThick III, signing off.

 

[Pepe Le Pew]

Nuts! How awesome is that!!! I wanna be like you guys, great job!