MOC Fairchild A10 (WIP) pics added

[Jeroen Ottens]

9 minutes ago, MinusAndy said:

I did look into a central drop tank but it would have to be far too big to fit the battery box in. There’s a couple of other parts that I felt could be upgraded too so this rebuild was inevitable really. My desk already looks like a crash site so it’s time to get back into it.

Another option would be to hide the batterybox in a stand. That way you can show off the working landinggear etc. without having to hold the plane in your hands.

[MinusAndy]

I also considered having a ground support vehicle with it in but I decided ages ago that I want this hung from my ceiling when it’s done. 

I now have this gearbox built and powered by two l-motors. The grey output is constant and will run the engines and the gun. The yellow and black outputs are switchable for direction and run the landing gear and flaps and slats.

 

Edited December 21, 2021 by MinusAndy

[MinusAndy]

A quick update on this. I’ve ended up entirely rebuilding the gearbox and switches, after exploring several mechanisms that used intricate timing of levers to disconnect the landing gear and flap mechanisms I have finally used differentials as a way to turn off the power input to the functions when the limits of movement are reached. I’ve also incorporated a large main spar which runs right through the model in order to keep the wings nice and stiff. I’m trying to keep my part count down as I have a tendency to overbuild using tiny elements rather than using frames and long lift arms instead.

 

in this final picture you can see the drive from the gearbox to the landing gear going through the output shafts of a differential. When resistance is met by the output the rotation is diverted through the crown wheel to the rotary selector catch.

I shall update this again soon when I’ve built the other wing and added the nose wheel. 

[MinusAndy]

I haven’t posted on here in ages, I got the a10 to a point where I couldn’t get the landing gear mechanism to work reliably in the way I want to so after several iterations of the gearbox for the landing gear I have decided to go down the pneumatic route and already the advantages are clear. So much part and hence weight reduction, which at large scale is vital I think.

I’ve built the nose section and wing root. The cockpit and controls are laid out, front undercarriage and door are now working perfectly using a single short piston.

I have a question regarding pneumatics: I’ll be building a pump that runs constantly using the same motor that runs the gun. I have an air tank (which is what the A10 is)

if I run the pump constantly is there a way to vent extra air from the system as I assume it will keep building until a pipe pops off.

thanks for reading and any help would be appreciated.

andy

Edited September 10, 2022 by MinusAndy
Added pics

[Johnny1360]

2 hours ago, MinusAndy said:

 

if I run the pump constantly is there a way to vent extra air from the system as I assume it will keep building until a pipe pops off.

 

I have never had such issues, so I think your good, maybe someone else will say differently though.

It is good to see you still working on this, I have been following it for some time now.

This thing will be an absolute masterpiece when finished, considering all the work you have put into it, I know what it's like to tear down a half completed build just to rebuild it better, enjoy.

[2GodBDGlory]

Yeah, I find that when using the small pumps, they'll just give up somewhere between 20 and 30 PSI, and just slip after that. I suppose you could add some kind of relief valve by hooking up a small cylinder to a valve, with a rubber band keeping it closed. If you got it tuned right, you could make it so that once the pressure got high enough, the cylinder would extend against the rubber band, open the valve, bleed pressure, and then shut it off again via the rubber band. It would be kind of like the auto-compressors people sometimes do, but with the opposite purpose! I've never gotten those compressors to work as well as I'd like, so I probably wouldn't try this. It'd probably be nasty to make reliable, and all the friction in the valve would be a challenge.

[MinusAndy]

Thanks folks. I think I’m going to put a clutch in front of the pump so I can disconnect it if necessary.

@Johnny1360 I don’t doubt there will be another strip down before it’s done!

[howitzer]

I believe there's an internal relief valve inside the pumps, exactly for this reason. Motorized pumps start to vent excess pressure in only a few seconds at most, without popping any hoses.

[MinusAndy]

Maybe I’ll try it as simple as possible first and see if there’s a problem.

[MinusAndy]

So following a lengthy period of head scratching, house moving, and general procrastination I’ve done some more work on this. 
I’ve managed to lower the height of the fuselage, connect up the knobs of god with both the joystick and rudder pedals and the control surfaces. 
the undercarriage and flaps are now pneumatic and I’m building an ejector seat around the buwizz that powers the engines and the pump and of course, the gun.

https://flic.kr/p/2pJ5b5S
 

https://flic.kr/p/2pJ5bGi
 

https://flic.kr/p/2pJ4zYE
 

https://flic.kr/p/2pHXmxg
 

thanks for looking. I’ll get on the case and finish this thing!

[2GodBDGlory]

Glad to see some progress on this ambitious model!

[MinusAndy]

Cheers man, I’ve spent the past couple of evenings making the canopy opening mechanism as I wanted it to slide and lift like the real deal. It’s now working nicely. (See video) but I will have to find a new home for the buwizz. 
https://flic.kr/p/2pJZqpM

I have the engines spinning, the pneumatic pump working and the gun but I can’t film and operate as it’s controlled by my phone so when I work this out I’ll upload some video.

[MinusAndy]

https://flic.kr/p/2q98uas 

I’ve started work on the wing. The main spar is done. 
im debating building split ailerons but they have to be 2 studs thick so that will be my next proper challenge. I think it’ll be done with the tiny pneumatic rams. 

[ukbajadave]

On 4/13/2024 at 4:33 PM, MinusAndy said:

...I wanted it to slide and lift...
https://flic.kr/p/2pJZqpM 

That's a very satisfying thing to watch  

Nice work.

[MinusAndy]

2 minutes ago, ukbajadave said:

That's a very satisfying thing to watch  

Nice work.

Thanks man. I thought I’d have to do something much more complex but for once the planets aligned and it worked with one ram straight away.

[Thirdwigg]

This has been a fun project to watch. I look forward to seeing it finished - it's getting closer.

[NV Lego technic]

Definitely looking forward to it! Usually I'm not a fan of technic planes and such things, but this one is an exception!

[MinusAndy]

So I’ve been turning my attention to the ailerons and the wing. My original plan was to use flaperons on this model (ailerons whose resting position can be changed so they act as flaps for low speed flight but still work as ailerons. I did this by routing the aileron motion through a differential in each wing. The cage of the diff is attached to the inboard flaps and as they lower it rotates the diff cage and that is multiplied onto the axle which controls the ailerons. It works pretty well but there’s an issue: the Hog doesn’t use flaperons, it uses ailerons that split into an upper and lower half. I’ve now built ailerons that are 2 studs thick and split using a tiny pneumatic cylinder. The return to close is done via an elastic band so the cylinder only requires one input and that can be hidden behind one of the many and varied instruments of death that this plane carries (probably not gonna submit this to Lego ideas)

It seems to work well so I’m sticking with this solution. This also means I can ditch the differentials and build more strength into the wing root. I can see a final strip down and rebuild of the whole plane when I’ve worked all this out. No biggie though, I only began building it a bees-dick over 4 years ago!

https://flic.kr/p/2qfnyaF

https://flic.kr/p/2qfnydm

Apologies for the mix of links and pics, I did exactly the same thing with each but half have embedded the image and half have not.

[NV Lego technic]

Nice progress!

[MinusAndy]

that’s the control surfaces all sketched into place. However, because I have changed how these work I am now able to build a cleaner and stronger wing root and main spar as it doesn’t have a differential in each wing any more. 
Not quite back to the drawing board with this but certainly back to a big pile of dark blueish grey prices on my desk while I rebuild the wing root. 

[NV Lego technic]

Looks very good!

[MinusAndy]

Thanks man. I’m really enthused by building at the minute, taking stuff to bits and rebuilding is a bit soul destroying but it has to be done or the rest of the build is a waste of time if I only half finish it and rush the last bits. 

[Thirdwigg]

Keep going! This project is great, and keeps getting better. 

[MinusAndy]

4 hours ago, Thirdwigg said:

Keep going! This project is great, and keeps getting better. 

Thanks man, that means a lot coming from someone like yourself. 

[MinusAndy]

I had a eureka moment at work today regarding creating subtle angles on the wings and body.

Using rigid hose inside pins allows the creation of smaller angles and is reasonably strong, especially when stacked.

Parts shown are the rear wing spar with the mountings for the split ailerons and flaps.