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A4 Skyhawk build

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Old 11-16-2012, 05:43 PM
  #101
Eddie P
 
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Default RE: A4 Skyhawk build

Looks great! How is the hydraulic NWS testing going?
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Old 11-17-2012, 12:04 AM
  #102
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Default RE: A4 Skyhawk build

Hi Eddie, I havent got the new cylinders yet although I've received the customs charge which is probably more than the cylinders are worth [] If the weathers ok the maiden will be on friday at RAF Alconbury. I've managed to persuade Ali to come up and lend a hand, well two thumbs actually... We'll see how the steering holds out then (fingers crossed)

Cheers, Alex
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Old 11-23-2012, 01:58 PM
  #103
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Default RE: A4 Skyhawk build

Its finally flown Thanks to Ali for making time for me and Steve for letting me use RAF Alconbury's runway. Cheers, Guys!

I was nervous with this model as I'd had problems with the tanks being odd shapes, gear doors that had bad geometry, hydraulic steering, a Powerbox i-gyro and leaky nose wheel oleo seal which I thought I'd fixed... All this was why I felt more comfortable with Ali doing the maiden. Having just watched him save a large scale bearcat from near disaster due to a mechanical failure I was confident there was no one better.

I can't say much regarding how it flew other than it looked great in the air and it's definitely a model that needs a gyro on the ailerons. Everything just worked, the hydraulic steering worked like a charm and so on... From the photos I can see one door was hanging slightly but this has a softer spring on it than the other. I'll order the correct spring as its sister door was nicely closed. We didn't get much of a chance to set the gyro up completely but managed to sort the aileron channel which improved its presentation markedly. You'll notice I taped the speed-brakes closed, this was due to needing two spare channels for the gyro set up so the speed-brakes were the first to go. Once its set up they can be re-assigned. only needs a coat of paint now

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Old 11-23-2012, 02:34 PM
  #104
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Default RE: A4 Skyhawk build

One other thing I thought interesting was its max recorded speed was 265kph this is the first time Ive used an on board GPS logger. I didn't think it looked that fast and Ali barely used more than half throttle on the flats from what I could see. Perhaps Ive never really thought about how fast or slow these models go before other than my perception of their speed.
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Old 11-23-2012, 03:13 PM
  #105
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Default RE: A4 Skyhawk build

Congratulations Alex, it looks great.
Looking forward to seeing in painted.

Geoff
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Old 11-23-2012, 03:34 PM
  #106
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Default RE: A4 Skyhawk build

Wow! This will be a fantastic aircraft when painted. Well done and nice choice in pilots making the maiden into a non event Though, the all grey paint must have been about the best camo scheme you could have (which way did it goooo!!!!) The A-4 is touchy on the ailerons isn't it. I am always amazed how little throw I have on mine and how fast the thing will roll on high rates.

Will be watching for more updates!
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Old 11-24-2012, 11:53 AM
  #107
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Default RE: A4 Skyhawk build

Thanks Geoff, Eddie

Ali did comment that the ailerons were a tad touchy and ended up on the lowest rate...

A few more pictures then I need to start getting it ready for the painter. Hopefully the paint job will be a nice Christmas present for me

Cheers, Alex




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Old 11-24-2012, 11:58 AM
  #108
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Default RE: A4 Skyhawk build

the real one had a roll rate of 720 degrees per second. the models will do roughly the same. it doesn't take much aileron deflection to roll the lil scooter

fantastic work amigo...I look forward to seeing her all dressed up.

are the tanks / pylons custom made or an option from Skymaster?
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Old 11-24-2012, 12:15 PM
  #109
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Default RE: A4 Skyhawk build

I did a self brief on the old posts in the thread. Very nice posts, thanks for documenting this build, I'm sure I'll be referring to it in the future!

I see you have held your paint scheme identity close for this project. Care to divulge??
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Old 11-25-2012, 03:19 AM
  #110
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Default RE: A4 Skyhawk build

Hi Guys, the wing pylons and drop tanks came with the kit. The center pylon I had spare from a previous build which was remarkably close to scale. I then bought a 500lb bomb for the center and I have two rocket pods for the outer pylons from an A10. The last flight Ali did had all the ordnance attached and he commented on running out of elevator on the flare which he hadn't with just the drop tanks attached.

The scheme Ive chosen is scale but not for the airframe Skymaster have modelled. It will be done in Argentinean colours of an A4C that was used in the Falklands war. Ive attached a few photos, the plastic model is accurate with the camo colours but the gear and gear doors were painted light blue on the full-size hence my blue undercarriage.

For those with a SM A4 the CG was set at 300mm from the front root where the wing buts up to the fuselage (drop tanks on & CAT full).

Ill post the pictures later when RCU lets me...
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Old 11-28-2012, 12:55 AM
  #111
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Default RE: A4 Skyhawk build

Now the photos are uploading and I've got another 3 hours to kill on Standby at the airport I'll finish updating the build to date.

I try to avoid doing hatches where possible as in most cases it adds unnecessary complexity. In this instance the model is looking tail heavy so the task was to get as much in the nose as possible but still be able to easily access it. The only option was to cut a few access panels. The A4 has these hatches on the full size and my model also replicates this so it was a matter of cutting around the panel lines.

I've used a snake to latch the panel which is accessible from the cockpit. The only action while at the field is to take the top cockpit frame off then pull the two snakes to open the panels. The pictures will show it better than my description...

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Old 11-28-2012, 12:58 AM
  #112
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Default RE: A4 Skyhawk build

The kit comes supplied with 4 pylons and two drop tanks. I was keen to include a center pylon with a 500lb free fall bomb as per the aircraft I'm modelling. A rummage in the loft found a suitable pylon that was close to scale. Thanks goes to Ali who gave me some pylons and rocket pods last year which he didn't need.

The centre pylon has to be removable otherwise it will be a real pain transporting the thing. I used the push fit keyhole method of attachment for both the pylon and bomb. I added some reinforcements into the fuz to create a hard point and made a few aluminium sway braces. The pylon needed to be profiled for the fuz so I used a sheet of ply and epoxy to get the desired shape. Its all done bar the final filling, sanding and priming.

The bomb was purchased from Fighteraces, it includes fins and some good quality resin pieces so should look the part once built! Its not scale in the A4 context but is close enough for me.
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Old 11-28-2012, 01:05 AM
  #113
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Default RE: A4 Skyhawk build

Keeping to the ordnance theme I decided to sort out the drop tanks. These tanks are large measuring just under 4 feet each. One of the things that struck me once all this ordnance is attached with the gear down and those huge doors hanging down is how draggy this is going to be.

With this in mind I'm going to make them dropable in flight. It could save me if the turbine stops plus I like the idea of dropping them on a flyby anyway...

Some BVM EZairs have been used and I've modified the tanks and pylons appropriately. I've just finished making the sway braces which are definitely needed. The tanks need some nose weight because they are tail heavy at the moment and any attempt to drop them with the CG so far behind the release point will end in tears.
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Old 11-28-2012, 01:09 AM
  #114
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Default RE: A4 Skyhawk build

The gear doors have had some rivet and litho plate detail added. Ive also wired up the servos and installed the 6 EZ airs for each wing.

I attach the male side to the fuz then build up the ply on the wing side cutting a slot in the wing. I attach them then slide the wing over with epoxy to fix in the correct position.
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Old 11-28-2012, 01:15 AM
  #115
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Default RE: A4 Skyhawk build

I made a couple of guns out of some plastic. I also had to make its housing as this wasn't on the left side of the molding for some reason. The main hatch is awkward to get off because the avionics hump doesn't allow it to raise slightly at the back. I could have added two more catches on the rear of the hatch but this would require four hands to remove. I decided on hinging the hump and the securing the back section with a spring allowing it to be removed with two catches. It needs to be cleaned up and sprayed its only in its R&D state in the pictures.

All the seam lines being given the treatment. Some of the seams would be more accurately described as canyons but with some work its looking more acceptable.

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Old 11-28-2012, 01:28 AM
  #116
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Default RE: A4 Skyhawk build

Ive added another bolt to the fin, originally it had one on the aft fin post but you could move the fin a little at the front so Ive added an additional bolt. Overkill?....perhaps but at least we'll never find out now.

The model has a few aerials here and there. I'm fed up of knocking stuff off models or having to be really carful when handling them for fear of knocking all the scale bits off. Ive used small 5mm Neodymium magnets, two on each aerial, the magnets protude into the fuze which also locks the ariel in place. None came off during the first few flights but I did accidentally knock a few off during fuelling and no CA required to replace
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Old 11-28-2012, 01:47 AM
  #117
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Default RE: A4 Skyhawk build

Alex, glad all went well and congratulations on the maiden. Looking forward to seeing it painted and just know its going to be a stunner

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Old 11-28-2012, 02:05 AM
  #118
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Default RE: A4 Skyhawk build

Photos do not do justice to how good this plane has been built. It was a pleasure to fly and every system worked flawlessly. A testimony to Alex's OCD

It felt pretty much as expected flying wise. Very roll sensitive ( Gyro essential in my opinion ). Also quite reactive to rudder, that was happier when turned down to low rate as well as the ailerons. Elevator was good and possible to over flare on the round out, and inverted needed a push of down... not too much, not too little so I would say centre of gravity was ok. Maybe could do with going a little rearward to try it, but nothing drastic. The oleo's were set a little soft for my liking, and we had a cross wind which made ground handling a little more of an effort. Nothing awful as I managed to get away without rubbing a drop tank... Phew! I was really impressed with how well and how proportional the hydraulic nose steering was. Lai Kai is a genius!
Cant wait to see it all painted up and back on the runway!
Regards Al
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Old 11-28-2012, 08:11 AM
  #119
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Default RE: A4 Skyhawk build


Quote:
ORIGINAL: Eddie P

Wow! This will be a fantastic aircraft when painted. Well done and nice choice in pilots making the maiden into a non event Though, the all grey paint must have been about the best camo scheme you could have (which way did it goooo!!!!) The A-4 is touchy on the ailerons isn't it. I am always amazed how little throw I have on mine and how fast the thing will roll on high rates.

Will be watching for more updates!
The real one was much the same way. It had a max roll rate of over 720 degrees per second. I'm guessing Ed Heineman did this so the pilot would have adequate roll control when the airplane was really loaded up with ordinance.
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Old 11-30-2012, 08:16 AM
  #120
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Default RE: A4 Skyhawk build

Im hoping it will look something like this...

Yet again I can't upload pics
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Old 11-30-2012, 09:23 AM
  #121
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Default RE: A4 Skyhawk build

The Argentine A-4 drivers were brave men with few resources beyond their personal abilities for example, during the Falklands conflict. Very historic paint schemes, those ones... and a great choice to model IMHO. Looking forward to more, especially when you can post some photos
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Old 11-30-2012, 09:42 AM
  #122
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Default RE: A4 Skyhawk build

Still not working but you can see a pic here:

www.facebook.com/TheLittleJetCompany

Yes I agree... brave men on both sides as in any conflict. The A4C missions were fascinating to read about must have been terrifying for both sides.

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Old 11-30-2012, 03:36 PM
  #123
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Default RE: A4 Skyhawk build

Alex and All,
A fantastic rendition of the A-4 Skyhawk and hope you have many successfull flights with the model. As a point of clarification, the A-4B version was initially purchased by the Argentine Air Force (AAF)and redesignated as an A-4P. The A-4C version was bought by their Navy and designated as the A-4Q. The AAF later purchased additional A-4C models which were refurbished as A-4Qs. Therefore, the Argentine Air Force operated both P andQ models while the Navy just flew the A-4Q.
Neitherversion incorporated the avionics package shown onyour modelwith the characteristic hump behind the cockpit. A smaller circular fairing was included and is depicted on the photo of the Little Jet Company's site. The vertical fin also has a circular loop antenna fitted and it appears to be a C model in AAF markings. These are moot points but important if you decide to enter the model in scale competition. Best of luck with your Skyhawk and it is a fitting tribute to those brave pilots that flew this aircraft in the Falklands conflict.

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Old 11-30-2012, 03:59 PM
  #124
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Default RE: A4 Skyhawk build

Thanks, my intention was to leave the hump off but it looked so good with it on I decided to keep it. I made it removable so it can be flown with or without the hump you can also change the fuelling probe from straight to cranked so it gives me and (if it lasts that long) future owners plenty of options.

you've made me want to make the antenna on the fin now...back to the work room I go.

Cheers Alex
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Old 12-01-2012, 04:59 AM
  #125
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Quote:
ORIGINAL: Alex48

Thanks Geoff, Eddie

Ali did comment that the ailerons were a tad touchy and ended up on the lowest rate...

A few more pictures then I need to start getting it ready for the painter. Hopefully the paint job will be a nice Christmas present for me

Cheers, Alex




Alex, fantastic shots, and a great build. Your extra effort and attention is really paying off on this. Have enjoyed the thread.
I noticed that you tucked away an iGyro in there. How did you (or Ali) like it? The more I read about it the more interesting it becomes.
Keep posting, this is a fascinating project.
[8D]
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