PSS A-10 Thunderbolt II - build blog

[Andy Meade]

Well, this'll slow things down for me in the workshop!

As some of you may know, I bought the bits for A10 number three from Phil (not Cooke, the other one!). This A10 is being built up a lot closer to plan, insofar as it using a built-up fuselage with stringers, formers and crutches, but using the same excellent wing that was cut all that time ago.

I've made reasonable progress, and just joining the second wing panel, as well as putting in the stringers for the fus and adding a wing box therein. My question is, what are you doing / have you done for an anti-rotation pin Phil? I can see what maybe looks like a 10 or 12mm carbon shaft in the wing crutch assembly that is in your fuselage in one of the pics. Ideally this would then go into a tube inside a wooden box in your wings, but as far as I can see you haven't done this as yet, or have missed the pictures from the build. Can you shed any light as to what you were thinking there please? I'm thinking this really needs to be tied into the wing skins too, or maybe not...the 1" square steel joiner will certainly add a lot to anti rotation all by itself.

I see form the RCG builds of the EDF versions of this beast that a nice cockpit moulding was available in the states - has anyone built anything up for this yet or moulded something similar? No worries if not, I'll just knock it up out of balsa.

I was hoping on having the tailplane / fin structure one piece. I can transport it like that easy enough, as I didn't want to add hardware (weight) in the tail if I can help it. The tailplane will still split from the fuselage as per plan, but my nacelles will be permanently fixed to the rear section and I'm splitting the fus just in front of F6, and using carbon-in-brass joiners. Can you see a problem with this at all?

Lastly, why did you decide against the inner flap sections? I know this will make it a 6 servo wing, but I think I'd like to see the extra flap area working.

I will post some pics tonight I hope of where my build is so far

[Matt Jones]

From memory it's 10mm Carbon rod that passes through the fus and into the wings sitting inside a Carbon tube to match.

Good to see you're on it already, might light a fire under Phil's posterior!

[Andy Meade]

Hmmm, cheers Matt. I have come up with a way of doing it, but if they were to really be anti-rotation pins, I'd expect them to be tied to the skins for strength, but can't see how Phil did his. If there is an easier way I'm always game to try something different!

I'd really really like to get this done for Lleyn this year, but means that the B24 and T50 (and Su27 and Hawk and... etc) will have to go in the loft and wait.

Edited By Andy Meade on 06/01/2015 14:01:22

[Phil Cooke]

You're going to embarrass me no end Andy if you finish your recently acquired Warthog before I do - but I'm struggling to work on my A-10 in parallel with all the other smaller PSS projects that get started and completed in the midst of the troughs in my A-10 mojo... saying all that, I cant believe it's been 7 months since I've updated this thread - shocking!

Anyway, I think I can answer your questions to keep you moving... I look forward to seeing your photos!!

Regarding the wings incidence pin - you are right, the ply wing root 'box' has been machined to accept a 12mm carbon rod which will run all the way through the fuselage and 4" into each wing panel. I will let a mating carbon tube into each wing panel. As you've seen - I haven't machined the holes yet in the wings to accept these tubes. I am not planning to build a box for them, but they will be glued into and through a 1/8th ply wing root which is already attached to the inner panel. This will give enough purchase on the pin, and the ply root DOES cover the entire section, including both top and bottom skins. So Im happy with that.

You are also right that the 25mm steel sq section wing joiner will also give quite a bit of anti-rotation - but I can confirm the incidence pin IS needed. With the wings on, I'm planning to retain them in place using a pair of large hooks screwed into blocks set into the wing root, onto which I'll use a threaded 'hoop and eye' arrangement like this... that'll keep the wings on no problems.

As a reminder - here's a view of the wing roots with ply faces... the hole shown here is for servo and wingtip light wiring, the incidence tube will be set aft of that once machined.

Regarding the cockpit, yes at 1/6th scale you are right this is a big feature and deserves some detail adding!! As you have seen there IS a vac form available to create the cockpit 'bathtub' and console, but I have simply cut a volume out of the white foam which I will line with 1/8th balsa and build up from scratch from there. I did buy a full figure pilot to suit and I aim to produce a stand off scale cockpit once the main building is complete.

Andy your logic on reducing weight by building as much of the airframe fully assembled is sound - I know that Simon has hard mounted his engine pods for the same reason - it will save you weight at the back end and significant time in the build too. The reasons why I have made mine removable is storage and transport. It's a huge voluminous chunk of model when the engines and tail are on - I just couldn't cope with it at home or in my car.

Finally, the inner flaps - I elected to leave them off for a number of reasons. Primarily, I was concerned about them being damaged on landing - the outer section is protected a little more by the height of the wheel pod and the dihedral of the outer wing. The inner I felt would be damaged each time the model was plonked in. Secondly, the flaps on the real A-10 are split so are not visible from the top surface when deployed - the top skin remains solid. So what I have modelled is over simplified and non-scale - in a way I was 'halving the error' by having flaps on the outer panel only. Thirdly, a 6 servo wing was over the top on a low performance PSS model in my opinion. I couldn't justify the time, cost, or complexity. I'm not convinced the flaps will be used excessively being honest. Maybe in marginal lift and on finals. Seems AGES ago now when I cut them out of the foam panels, but these are the reasons for my outboard only flaps.

[Andy Meade]

Thanks for the replies Phil, I will inwardly digest and hopefully not mess your thread up too much!

Here is my progress so far - yes I'm splitting the flaps and ailerons out after joining the wings - didn't think I could get them aligned otherwise.

Filled up the dining room somewhat!

[Phil Cooke]

Nice one Andy, you'll not be popular for very long leaving a 110" span model on the dining room table

I've not described the flaps too well in re-reading my text, they are not a true split flap, like on a Spitfire, what I was trying to say was the top surface of the wing doesn't drop away on the fullsize like my simple bottom hinged flap system will - if you look at the MIBO Turbine model they have done the flaps true scale, they are highly complex assemblies - too much for us boys who neglect to fit the retracts!!

Edited By Phil Cooke on 06/01/2015 22:44:02

[Andy Meade]

All coming along here - just the tips to put on now and the wings will be done, short of hinging the control surfaces. Will buy the main spar this weekend, and also hopefully get cutting some foam for the tail assembly. Drew up an Excel file with costs of what I have left to buy for the A10...scared myself a little!

[Phil Cooke]

Yes the costs involved in building and finishing a big model (even with low tech materials like foam and veneer) do mount up don't they! It sounds like you've made some good progress in a short time on the wing panels then Andy, great work.

I will be interested to see how you decide to tackle the wing tips - I considered a few options before finally making my pair as a balsa and ply fabrication - making one was ok, making the other look visually identical was the challenge!! I will be watching your progress.

(Above) - prior to final sanding and (Below) - fitted and finally shaped.

Must crack on and get the PSS Tornado finished and off the board so I can work my A-10 further - your progress is motivational!

[Fly_Boy_Rez]

Fantastic! Two A-10s for the slope! This deserves a build blog of its own Andy!!!!

[Andy Meade]

Hi Rez!

Yes really looking forward to seeing both of these strafing the pits at the Orme

Not sure I can embarrass myself with a build thread of my own though!

[joseph courtney]

Hi Phil,

Man you have done an amazing job. If you don't mind me asking, by chance were did you get the plans again? I would love to do the same A10 and the same size.

Thanks

Joe

[Andy Meade]

His name is Josh Harel, and you can find him on RCGroups. Alternatively, send me your email address via private message.

[Phil Cooke]

Rather embarrassingly the A-10 has been sat in the corner of my garage for the past couple of years(!) – held back by a few smaller, ‘faster from start to finish’ build projects being completed and more recently the PSSA 30th Anniversary activities which had to be prioritised. Anyway, with no more deadlines looming I’ve blown the balsa dust off the airframe and this week the front nose section found its way back to the building board.

My original plan was to mount the Rx batteries in the wing bay, but with the learning gained from Andy Meade completing and flying his similar PSS machine, it’s clear that the weight is needed right up front so a battery box has been ‘let in’ as far forward as I can muster, with the cells sat up behind F1. The model will fly with a pair of 5000maH 2 cell 7.4V Li-Pos, and a cavity was cut and lined to suit their dimensions.

The cells are retained by 2 velcro straps in the tailored box, the reinforced cover is held with a pair of M3 bolts and captive nuts mounted into hardwood bearers. I still have to route the cabling from this battery box under the cockpit floor and into the main cavity ahead of the wing. A little more fairing in and a final sand will see this addition complete.

Edited By Phil Cooke on 05/12/2016 19:29:34

[Andy Meade]

Oh my good gravy....it's back! When do you fancy yours to be ready chief?

[Scott Edwards 2]

Oooh don't pressurise our glorious leader ! Just be grateful it's out of the corner, and one day we could see a formation of Giant A10's in the air ! Oh be still my beating heart

[Phil Cooke]

I really don't want to set myself up for a fall by declaring another target date Andy... but once the canopy area is sorted on this nose section and I've fitted the fuselage joining tubes/bearers then the airframe is effectively ready for glass.

I should be targeting a finished model in time for the start of the next PSSA mass build project which is due to commence towards the end of 2017 so we can build over that winter...

[Matt Jones]

Holy Time Team Batman!!! I hadn't realised the Internet was that old until I checked the date of the first post....

[Phil Cooke]

Touché Matt. Good to have it back on the bench...

[eflightray]

Now if you had a simple plug-in motor system ........

She could have a little extra versitality

Ray

[Andy Meade]

Hmmm spinny noise makers

[Matt Jones]

Sweet Hog, Ray.

[Chris Barlow]

Just spent the last hour reading this whole awesome blog and just have to say...

"Get yer finger out Phil. It's about time this thing flew "

Interesting to read you have been contemplating the same issues I've been thinking about with my smaller A-10 regarding landing and the tail/fins. I have mounted my tail with 3 nylon bolts which I hope will snap if the tail gets snagged. Also the angle of the engine pods to wing incidence which on mine I'm sure will create a pitch down moment. Will have to see when I throw it off a hill!

Your build is amazing as usual though and I'm really looking forward to the glassing and painting stage. I have decided to go for the green/green/grey scheme with probably a shark mouth for effect on my little 'un, stand off scale from the Orme as viewed from Llandudno pier!

[Andy Meade]

I dare say the fins will be fine on a lighter Hog, Chris. The biggest problem with mine in that area, is the upward force applied to the tailplane by the fins sitting on the ground. I have a stress crack in the underside of my TP after my last hard landing, but I intend to remake the tail anyway to make it lighter.

[Phil Cooke]

Mine will hopefully slide off to solve the tailplane loading problem, but this might not work that well on uneven ground...time will tell.

[Phil Cooke]

The main reason for further work needed on the front fuselage section relates to the fit of the vac formed canopy. The way in which the white foam panels were cut straight with a bow between 2 formers has rendered the 'shoulders' of the fuselage section too thin for the canopy to sit at the required height - it needed a more rounded, bulbous surface to mate up to.

Sadly, the best way to correct this involved cutting out the top section around the canopy and replacing it with a bigger volume of blue foam which will then be sanded to the correct profile and 3D contours. One advantage of this approach means I can build up now a balsa cockpit bathtub, glue that in position and then clad blue foam blocks around that prior to sanding. Removing this volume of material will also aid me in creating the wiring channel still required from the battery box up front to the rear of this section.

The shaded area is to be removed and scrapped

It came away quite cleanly with a scalpel and thin kitchen knife...

The foam surfaces were tidied up a little...

and the cockpit floor was resized to scale drawings... now to build the bathtub!