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Nov 12, 2016, 05:31 AM
Isaiah 40:31
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Build Log

Incom T-65 X-wing Starfighter - Pusher


Another new design, the X-wing fighter inspired by the Star Wars films. complete with opening / closing wings.

800mm wingspan (closed) 910mm long

Its NOT TESTED YET!, but I wanted to make a start.

I've got lots of projects on the go at the moment, and I do what I can when I can on all of them. so my apologies if you are waiting for me to finish something that I've not finished yet. If you are that person, please let me know what you are wanting to build and I'll try and put effort into that project to help you.
Last edited by Clickety; Nov 12, 2016 at 09:27 AM.
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Nov 12, 2016, 11:46 AM
non pro car designer.
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Awesome
Nov 12, 2016, 12:04 PM
Isaiah 40:31
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Thanks! Let's hope it flys well!!
Nov 20, 2016, 12:19 PM
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Well, there is that old saying, "if it looks good, it will fly good."

And they didn't have multiaxis flight stabilizers back then, either.
Nov 20, 2016, 12:26 PM
Isaiah 40:31
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True, but I don't think it will need one.

The biggest problem with the x-wing is that it has no vertical stabiliser. By adding them I'm confident it should fly.

Ramy has made one that flies ok without one!

STAR WARS: RC X-wing EDF maiden flight [Ramy RC] (5 min 24 sec)
Dec 02, 2016, 10:49 PM
gs1
gs1
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Hi Craig, I think I will have to give this one a try! Ramy indicated the CG was on the leading edge of his version, do you expect similar for yours?
Dec 03, 2016, 02:12 AM
Isaiah 40:31
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You're a brave soul Gareth

I am so busy with my new job and my new life in Bournemouth, that I've not had chance to do much building, but designing has been easier as I can do that on my laptop anywhere... With this project, I really hoped I could get her flying in time for the new Star Wars film! but that was only a pipe dream!!

So if you wanna be the test pilot, I will tell you of how I was gonna do this if it helps you with yours!

Firstly, the CG position. Ramy said this about his CG :-

' its between the wing edge and 4 cm from it to the front, my model was 1.2 meter long fuselage'

I take that to mean that it is ahead of the wing by 4cm(??). As my design is only .91 metres long. it would need to be (scaling pro-rata) approx 3cm forward of the wing. However, I don't have a horizontal stabiliser on my design as per Ramy's, which would increase the lift surface area forward and move the CG forward a touch. My best guess for this plane would be around 2.5cm ahead of the wing. That is with the wings in the open position.

The amount of lift generated by the wings will change according to whether the wings are open or closed due to the amount of lifting area exposed to the flowing air. This would mean that as the centre of lift is ahead of the the wing, then with the wings closed it will bring the nose up in flight. So If we get it to fly with the wings 'open' then when we close the wings it might make it very nose light (tail heavy)... we'll see.... That is a problem to solve at the flight testing stage.

My plan was to make a very simple non moving wing glider to test the estimated CG, and throw it into long grass. I was going to leave all appendages such as the nacelles and laser cannons off at that stage, as that would add an extra complication which we don't need at this stage. I was going to use a movable weight suspended beneath it to experiment with the CG position. (bit of metal taped to the belly)

It is imperative that the CG for the model is bang on, as it will tend to have a small CG margin, due to the lack of canards/horizontal stabiliser.

If the plane tends to yaw, then we will need to make bigger vertical stabilisers. for the glider, I would make these in depron so that we can easily detract / add more area if needed. Against Ramy's advice, I didn't want to put rudders on, as I tend not to use them, and none of my parkjets have rudders, I also wanted to make sure that the vertical stabilisers were 'invisible' so that it looked like a 'proper' X-wing in flight. I would like to make the plane have the smallest possible vertical stabilisers possible, in order to 'hide' them. but obviously it needs to fly first!!

If they are too large, the plane will tend to want to go into a spiral in on a tight turn, as they will act as lifting surfaces, so then we would need to trim them back a little.

If we get the plane to glide ok, then the next step is to try the powered one. similar fashion - no nacelles / cannons. Then get a friend to hand launch, and see what happens...

My plan would be to launch with wings open and then if it flies, then to use that flight to tweak the CG, and test the throws. (start with +/- 30 degrees with 40% expo)

If it flies, and the throws are dialled in, then the next stage would be to fly high, and see what happens with the closing of the wings, perhaps a buddy could operate the wings while you fly in case it becomes difficult to control. If as I suspect it goes nose light, the question is, is it possible to find a common CG for the plane to fly ok in both states. if not, then I will look at making a way to shift weight inside the plane for both states. maybe a sliding battery tray on a servo....

Once that's been figured out, then I was going to prepare a fully prepared set of graphics for the whole plane, so that it would look the part.....

Anyhow, I am excited to see your progress. please post step by step pics / videos, so you can share with the world how you are getting on?

All the best

Hey please join my Facebook group page with your postings too!

Craig
Last edited by Clickety; Dec 03, 2016 at 02:22 AM.
Dec 04, 2016, 05:12 AM
gs1
gs1
Registered User
Thanks for all the advice Craig, I agree a glider to check CG is the way to go, I will probably go with fixed wings to keep things simple and a project I can complete in December - I will be very happy if it flies like that!
Dec 04, 2016, 04:38 PM
Isaiah 40:31
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I'm particularly excited to see this one fly, please post pics vids etc. Landings may be a bit tricky with open wings though... Just a thought..
Dec 06, 2016, 03:28 AM
Isaiah 40:31
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Gareth, just remembered, I guessed at the clear plastic thickness. I need to physically flex the plastic in my fingers to estimate the exact plastic sheet thickness. I suspect the 2mm will be too thick and heavy, but I have no frame of reference.
Dec 06, 2016, 03:48 PM
gs1
gs1
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I agree 2mm seems a bit thick, hopefully when I find someone who sells plastic or perspex they will have a few options available. I printed plans today, starting a with a 60% version for construction (3mm depron) and initial flight testing and once that is proven will move onto the 100% version. I think it will need a nose skid like the original to keep the nose up on landing, will see what I can do to make it retractable. I was also thinking of having vertical stabilisers extending under the body to try and take the stress off the lower wings on landings. Will test this out on the 60%...
Dec 17, 2016, 04:23 AM
gs1
gs1
Registered User
It flies! The CG is definitely better close to the leading edge, for the first attempt the CG was 2cm in front of the LE, and it torpedoed into the grass despite applying full up. Once the CG was close to the LE it was very stable and flew well but there are some challenges to overcome:

1. There was still insufficient pitch authority, and once I lost some speed it was very difficult to get the nose up and gain some height, I will check the CG more accurately and possibly adjust a little bit more. This also makes landings tough as it was impossible to flare.
2. Landing punishes the lower wings as expected, this was worse landing in thicker grass as I added extended lower fins which helped on flatter landing sites. I just taped the fins on, they need some proper structure to support them now.
3. Visibility was challenging when you see it side on due to the clear fins going invisible, hopefully a paint job will help.
4. My bracing of the fixed wings wasn't strong enough, I will add more structure to support the lower wings...

So in my opinion it is a winner Craig, well done! The full size should benefit from a lower wing loading and maybe this will also help the pitch authority, it looks awesome in the air, will get a video in due course, it was rather windy this morning so I was the only maniac trying to fly anything (it handled the wind well BTW).

The photo here is after some field patch work using the ever handy masking tape...
Dec 17, 2016, 06:18 AM
Isaiah 40:31
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Thanks for posting Gareth, That is So exciting! Perhaps shuffling the CG further back will help the pitch authority l, I would suggest increments of no more than 3mm at a time.

I'm so pleased! Are you taking it out again soon?
Dec 20, 2016, 03:28 PM
gs1
gs1
Registered User
The x-wing flew nicely with the CG 5mm behind the leading edge of the wing, I am a bit scared of moving it much further back. Pitch authority at slower speeds was still very sluggish. I will test out keeping the CG as is and adding a canard like other folks have done, as per the photo. I am also confident enough to start adding some colour! The fins are now glued in and I have made the wing support structure more robust with some foam bracing between the wings.
Dec 20, 2016, 04:42 PM
Isaiah 40:31
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So pleased that it's flying better. I would suggest you try and perfect the CG before adding a canard, I originally was going to add a canard right at the nose, but was hoping to avoid it unless I have to. The fact at slow speed it is wanting to nosedive could be a high stall speed, or that the CG is still too far forward. Adding a canard will move the CG position forward. Can you get a video? Might help solve the riddle.


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