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Nov 08, 2017, 10:22 PM
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Build Log

Bae Hawk - FlyFly 90mm

Another jet.... a bit soon, but I will see what order it can sneak into amongst the others to do.

I had been aiming to get ALL FlyFly jets eventually, plus had my eye on the Hawk for a long time now. So today I decided to get it and see when I will build it.
After a lot of pondering over the color scheme to get, I ordered the all BLUE version. But within 20 minutes I changed my mind and altered it to the 2012 (?) Anniversary Scheme one (Black, Red, White, Blue). I decided that it is pretty unique and narrowly 'wins' over all the plainer schemes.

1365mm Wingspan and 1465mm in length - it is fairly big, so its Scale is relatively 'large' - and that means it has 'substance/volume' seeing it is closer to the full scale. (than a smaller scale - or some large real aircraft with this scale model dimensions).

I will make it 'full house', with Flaps, Retracts, nose gear doors and use 8S. Likely a HET/Jetfan 1500kv or 1600kv setup.
From all that I have read and see about it, this is a very nice jet and worthy of making it up as a 'quality' RC model. (certainly NOT just as FlyFly supply it!!!)

Last edited by PeterVRC; Jul 29, 2018 at 10:05 AM.
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Nov 30, 2017, 09:16 AM
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BAe Hawk arrives

The Hawk actually turned up on 25th Nov (6 days ago).
It is NICE!
I would say it is probably the best FlyFly jet.

1) It is BULKY - as per the F-86 Sabre - because their 'scale ratios' are less than other larger aircraft done to the same length or wingspan.
So you get a lot of foam and jet for your money!

2) Pretty well every METHOD of what they have done for all its features, are laid out in a very good/nice way. So this part is the main thing that gives it that 'best' lead.

After having looked for more pictures of this full scale "Anniversary" paint scheme, it was actually the 2010 Anniversary - NOT the 2012 as FlyFly stick (decals) on it! FlyFly NAME it the 2010 - but the DECALS are the 2012 year. (see pics in the first post)
I have not checked the DECALS to see what they really supply..... but it seems it is the wrong year.

The painting is done VERY WELL. Especially for a somewhat complex scheme that it is.

They also have 'new' landing gear, which is still "minimalist" but WAY better than the original landing gear that Fly Fly gave!
They actually verge on being USABLE !!!
Probably fine for people using a HARD runway.

Versus the set I bought for it at AUD$80 approx!! But of course those are WAY better, and much sturdier and very well made... pretty well needed for grass runway use really.
BUT.... I was very surprised at how much better the FlyFly new landing gear are now!

Pics of the 2010 Ann scheme below.... as well as three of the real 2012 scheme.

Last edited by PeterVRC; Jul 29, 2018 at 10:07 AM.
Mar 23, 2018, 12:50 AM
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Wing Spar/s

A quick start of a bit on the Bae Hawk....
The first thing required is to mount the Main Landing Gear into the Wing because you need to calculate what the nose wheel height needs to be. This comes about because a chosen main gear set is a certain length (height) and you will need to match that.
I would never use the FlyFly stock gear anyway, but it is way too tall... about 20mm too tall and makes the aircraft look like it is on stilts!

So to mount the main gear into the Wing, to do the above checks, you need to JOIN the Wing and make all their mounts etc......

I decided I will use one large and long 8mm carbon fiber spar as the main spar, and a secondary shorter 6mm spar towards the rear end of the wing chord - but still well away from the Flaps area.

The Hawk has two sets of plywood wing braces, a front end joiner plate and a rear end joiner plate. That is all they give you and expect to be used(!!) but they are still great to have and use.... WITH some carbon fiber spars added!!!
Their plywood pieces are useful for locating the joined edges and assist in the gluing process because you can use Polyurethane glue for the two Wing mating faces, but Epoxy on those four plywood joiner pieces so they dry fast and hold the Wing all together whilst the Polyurethane glue takes an hour or few to set!
Polyurethane glue expands, so this is good for around spars, to make them 'become' a tight fit into the foam 'tunnel' you make for them. it is also good for the Wing facing joints because those rarely mate up anywhere near flat and perfect, so the PU glue expands to fill that joint fully.

The rear spar, being short meant it is easy enough to use screwdrivers to 'drill' the spar hole required.
You almost never can get those holes accurately aligned but you can hack/drill away at the hole to make the spar able to line up across side to side - which then leaves portions larger than just the spar, but that is where the PU glue FILLS any space there anyway.

The longer 750mm main spar can be slotted in AFTER the Wing joining. It only needs a portion of the Wing centre section (underneath side) cut out - a channel formed - and also "U" cuts into some of the Wing 'ribs' in the foam. Then it is PU glued in, with foam pieces of the prior cut out channels put back in over the spar. Thus it all ends up like 'new' (the surfaces) and even stronger than ever as PU glue is stronger than foam anyway.

The main spar runs right under the forwards end of the main gear retract mounting plates. This is so that they also glue onto the spars and form a complete "left gear to right gear sub-frame" in total. All landing stresses go right across the wing from left to right.

I will do the main spar and retract mounting plates very soon....

Last edited by PeterVRC; May 04, 2018 at 08:22 AM.
Mar 23, 2018, 12:51 AM
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Main gear mounting plates, retracts and oleos

I assessed and measured up the main gear mounting plates and made them from 4mm 5 ply plywood.
Part of that design was to include a 12mm carbon fiber tube spar that runs across from plate to plate - in the foam deeper to be under and against the plate lower surface.
To make it easy to add the spar I just cut a 12mm DEEP slot across the wing centre and kept the main cutout piece so that it could be replaced to complete the wing section and surface back to shape etc.

The spar was put in with Polyurethane glue so that it expands and fills, 'wraps around' the entire spar through that wing centre area. The further outwards portions were epoxied in, as well as the replaced foam centre piece, because 5min epoxy sets fast and then will keep things in place as the PU glue expands and dries. Due to the PU glue, the wing centre section will be stronger than the stock foam ever was anyway!

The retract mount plates were recessed down into the wing enough so that the retracts own mounting plates will be flush to the wing underside. Because I used the LARGE type PZ retracts, which are quite large really(!), I had to dig down a bit more into the wing to achieve all that required height - maybe 2mm deeper than the stock retract channels were. Still plenty of foam 'above' to the wing upper surface.

With the large plywood mounting plates, 'attached' to the very large 12mm 'sub-frame' spar, the main landing gear will be extremely tough and cope with massively harsh impacts if they occur! Plus with the Trailing Link type oleos that will already absorb a huge amount of energy anyway.

Last edited by PeterVRC; May 04, 2018 at 08:23 AM.
Mar 25, 2018, 05:50 PM
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The main Wing Spar

Originally the forwards Wing Spar was going to be the 'main' spar, so I had put in a smaller shorter rearwards spar already, but once I worked out the main landing gear method and pieces I could see that to have a decent main spar length/span it would need to be quite far rearwards in the wing - pretty well right where the first smaller spar had been put in!
That was OK as the new main spar could run right after that original spar.

I used a 12mm x 750mm carbon fiber tube, cutting its channel/slot across the wing centre section as per the landing gear spar had been done.
In a way the original smaller spar was more of a way to have a Wing Joiner to help the initial wing joining and alignments. Along with the stock plywood joiners FlyFly provide.

The more rearwards Main Spar is an ideal position for it - away from the landing gear but also close to the optimal wing chord position for high strength too. So all in all, the main gear spar and main spar all worked out a great way to set this all up!

As per the main gear spar, the main spar was PU glued in, but with epoxy used for its end portions and the replacement centre foam piece. So once again the centre wing section becomes stronger than stock and the spar is 'wrapped' and bonded to a lot of the wing span area it passes by.

I was going to add some strips of 6mm x 1mm carbon fiber to run further out to the wing tips, but it doesn't really need any more strength out there now. Though I might just do them anyway.....

Last edited by PeterVRC; May 04, 2018 at 08:24 AM.
Mar 25, 2018, 06:01 PM
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Nose gear and steering

Once I had the main landing gear fitted I could put together the fuselage and wing for set up a plane to see it intended/required rake/stance from the landing gear lengths. This is so that I could adjust the nose gear to suit what I wanted.
A quick test showed it was going to work out very nicely - good positioning and room in the nose for all the items required for the nose gear assembly, and storing the nose gear fully to allow for gear doors.

I made up a 4mm mounting plate to bridge the span of two foam bulkheads in the nose. This has 4x 3mm captive nuts in if for the retract.
All the required work could be done into one side/half of the fuselage and just fitting the other side to test things as I went - then go back to just the half being worked on.

The main gear mount was placed 4mm higher into the nose than it needs to be. This was done to allow a 'spacer' plate to be used in between the mount and the retract itself and thus allows 'tuning' of the nose height to set the static AoA stance to whatever ends up working nicest for take-offs. eg There is about an 8mm range that runs from -4mm stance (negative AoA) out to +4mm stance (positive AoA).
Full scale aircraft tend to have a negative AoA stance, but RC EDF models take off 'nicer' if they have a slight Positive AoA stance.

I made an alloy mounting plate for the PZ Large type retract itself - as they do not come with a plate for mounting them via their 'top'.
It is always much cleaner to mount nose retracts from their top as then it gives complete freedom and space all around the retract, for the steering assembly and pushrod etc. It also makes the main fuselage mount much easier to make as it is just a flat plate then! It is just the best way to do nose gear!

A 2.8mm 5 ply plywood plate was epoxied running forwards of the main gear plate, for the steering servo.
This also just fits in easily and nicely to the space that is ahead there.
The servo is fully accessible via the opening under the nose

The nose underside opening will have cover plates for them (thin plastic most likely), and I might also put a nose gear door on - seeing there is a ton of space for doing that easily. (Hawks have two doors, for half the width required each).

Last edited by PeterVRC; Mar 25, 2018 at 06:07 PM.
Apr 14, 2018, 09:58 AM
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Fuselage - Battery area and tray extended

For a typical 6S setup the battery is fed rearwards into the stock battery area.
With all the various 'extras' I am including, it is unknown as to what sort of balance result that will all give so I decided to make the battery placements have the maximum possibilities for shifting them to suit. Hopefully enough range to cover any possible need!

The first thing to do was to extend the stock battery area to be longer and more rearwards.
For 7S and 8S there are TWO 5000mAH batteries being used:
For 7S it would use 4S 5000mAH and 3S 5000mAH.
For 8S it would use 2x 4S 5000mAh.
and there is not enough length still to fit them nose to tail on that main battery tray - and even if you could, that would never balance out right anyway. They will pretty surely need to be 'stacked' vertically.

So one battery goes wherever suits it all best on that lower tray, but the second battery goes on a higher up tray that is staggered to be more rearwards than the lower tray.

Whilst working things out it brought about a 'link' to having a 'Ducting Divider' to 'taper' the airflow to a center point, rather than the stock 'blunt rounded' centerline fuselage join. When you add this Ducting Divider it means there is even moire room for batteries to go more rearwards than stock, because they can continue on into that Divider area - which isn't there in the stock Fuselage.

So I had to make up those Dividers (one per Fuselage half) first.....

Apr 14, 2018, 10:06 AM
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Inlet Ducting Divider

This idea was brought to light (for me) by 4Stripes's build of his Hawk.

Rather than leaving the centerline inlet ducting shape to be a 'blunt' rounded shape, you can add some balsa wood 'walls' to extend that narrowing to a point, after a fairly long tapering down period. That is very easy to add!
Well, except for working out the SHAPE that the balsa 'walls' need to be! So with some stiff card to cut and work out the shape, I made a template which then could be used to cut the balsa wood to the right shape.....

Once these were in, the extra centerline area that gives could be looked at to see how much more rearwards the UPPER battery tray could run. The lower tray can't go much further rearwards and doesn't even need to anyway. You really want the batteries 'staggered' for ease of installation and removal. Thus the upper battery is the one that goes a fair way more rearwards. And again, this being the 'base' battery means the other lower battery is the one you will be moving to fine tune the final CofG.

It was easy to work out what foam areas to cut out to give that larger battery area. it is just 'extensions' of the pre-existing battery area opening anyway.

Note that the SBEC will go to the very front of the lower battery tray, and the RX will go up on the 'top rear deck', above the upper battery, under the canopy.

Last edited by PeterVRC; May 04, 2018 at 08:27 AM.
Apr 14, 2018, 10:14 AM
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The ORDER of assembly !

All along the way of doing things I am always looking at an assessing HOW could you do something - all things - "best". And what does that mean you will need to do, and in WHAT ORDER.

All the things done so far could be done with the Hawk still in its original separate pieces and that is very handy! But at some stage some parts will need to be joined.... then some more things done.. then more joined...
So I have determined that ORDER....

As has been seen in prior posts, all the Nose Gear stuff - which includes if you are adding nose gear doors, and/or the nose light - will be done with the two forwards halves UNJOINED. All things done can be only glued to ONE HALF, and tested with the other half held together, then separated again to continue to do more things as required.

Inlet Ducting Dividers, which need to be done before adding the upper battery tray, mean you need to do those while the front fuselage portions are still separate. so anyway, you need to do ALL things that the front portions require internally, before they are ever joined.

But after some thought about construction I decided the order to assemble it will be to create the two COMPLETE fuselage SIDE HALVES first. Once all the internal nose stuff is done then the LEFT REAR is joined to the LEFT FRONT. And the same for the right sides.
The very final joint will be the COMPLETE Left and Right halves eventually.
Every thing fitted is done into one half. eg RIGHT SIDE half in mine. Later on SOME things will be done to the left side - such as the nose light and wiring runs, and nose gear door wiring.

So anyway, it will be a COMPLETE Left and Right side that eventually get joined.....
Last edited by PeterVRC; May 04, 2018 at 08:28 AM.
Apr 14, 2018, 10:33 AM
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Removable rear end (!!!)

Now for a quite surprising IDEA I had, and will do.....

The EDF area and its cover are WAY too small to ever get an EDF BACK OUT of the Hawk! You can extend the EDF cover SOME amount, but even then it will just be very restrictive and difficult. More so if you have a 'larger' EDF type. A longer EDF housing, and a large Inrunner motor extending a fair way out the rear of that.
My friend, who is also building one - in unison with mine - will use a CS12 with Fandrive 3968 motor and that is LONG. No hatch could allow that to ever come out again!

I recalled my 64mm Mig-15..... which has a completely removable rear fuselage - exactly like a full scale Sabre does (and many other jets have also). It comes apart right near the EDF and is 'bolted' to the front half of the whole jet.
This is so EASY to do!! And makes maintenance extremely easy then too! Again, just as per the full scale Sabre does for that exact reason too. Easy and FAST engine access and removal/exchange!

After looking more at the Hawk, I decided to make it that front and half ends of the fuselage join using the 'step' formed by the EDF Cover cutout - not a flat face to face joint. This is much stronger and gives better 'locating' ability.
It also allows the EDF to be fully bolted to the front fuselage portion so that when the rear end is removed it leaves the EDF sitting in plain view there.

The EDF wiring runs through the fuselage foam bulkhead that is BETWEEN the rear of the EDF and the thrust tube, thus it is easily fed through too.
Rear end servo wiring and/or lights etc are through a single plug that resides in the cavity the fuselage has above the EDF , so as the rear fuselage half is backed out you will get access to disconnect the plug. Then the rear end is totally free of any connection to the front half.

This is going to be an awesome "Super Mod" to the Hawk, and will make its EDF maintenance extremely easy. It will also allow very easy EDF removal if you want to use it in another jet.
That would already be easy in the stock Hawk layout IF the stock hatch could even let them out.... but it can't.
For this mod there is not 'hatch' anymore - the whole rear end uncovers the EDF fully!

The above "details" are brief - there is a lot more done to produce the required result, but it is not very hard to do at all, as you will see further down the track....
Last edited by PeterVRC; May 04, 2018 at 08:35 AM.
Apr 15, 2018, 06:23 AM
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EDF unit and mounting

For the Hawk I bought another GRP-HET / Jetfan rotor / HET 650-1600kv combo from ExtremeRC (Australia).
These are ready to use, very well balanced, and highly efficient EDF combos!
Probably triple the price of a budget EDF setup but you get return from the much higher efficiency, being ready to use when it arrives (no assembly and balancing etc) and it a 'premium' set of items that will last long term too.

Seeing it is a HET housing, it is an almost identical match to the stock FlyFly "HET rip-off" housing anyway! So it almost fits straight in. The GRP housing is thicker and thus a slightly larger diameter so a bit of sanding of the EDF bay is required,

I made some 4.5mm thick multi-layer plywood mounts - seeing the kit did not come with any! Then bolted the EDF unit in, so that I could investigate the best way to make the tail end separation.
It stood out that using the stock EDF hatch/cover 'faces' would make for a nicer joint AND allows the join to actually be a 'step' - not just a flat face to face fit.
So I cut that off and it all worked out very well !!

I put in a pair of 7mm Alloy tubes, which fit and will use 6mm Carbon Fiber ROD to bridge the fuselage joint to locate it accurately, and be a part of the system used to gain 'strength' over the joint. I might add two more, but I will test the joint strength in this format first and then decide if it needs more or not.
Most likely I will use an upper and lower plywood plate on the fuselage outer surface to hold the join in place. The tube/rods do all the "anti angle" aspect of it - keeping the fuselage perfectly in line - and the two ply joiner plates do the "keep it firmly together" part of it.

Last edited by PeterVRC; May 04, 2018 at 08:38 AM.
Apr 15, 2018, 06:43 AM
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After some thought about it all, I decided to make the Stabilators joined together and driven by a single larger servo.
This is quite an easy thing to do really.

The stock pivot blocks are used in their usual manner, but they are drilled out to take 5mm shaft instead of the paltry 3mm stock shafts!
A single 5mm stainless steel shaft is used and extends 50mm out each fuselage side, from the pivot block.

To drive the shaft, a nylon steering arm, for 5mm shafts, is used as a Control Horn. It is set within the fuselage but heading UPWARDS and its arm end comes out the fuselage, alongside the fin, by about 8mm or so.
This is connected to the single servo which lies on its SIDE in the stock servo area, just that it has a plywood mounting plate put into the fuselage there to allow fitting a servo 'mount' for that.

To attach the Stabilators, the same type of 5mm steering arm is fitted into the Stabilator and epoxied into it, so that the 5mm shaft runs through that and deeper into the Stabilator. (50mm in total). Either side of the Control Horn (Steering Arm) there is a short piece of Brass Tube, to suit the 5mm shaft, it is epoxied into the Stabilator to extend the supported area (surface area) of the rod.... and making sure the Steering Arm fitting and the shaft are not glued to each other the Stabilator! It is also 5mm longer out than the Stabilator inner Face so that it sets the Fuselage to Stabilator GAP.
Then another 30mm piece of Brass Tube is used outboard of the 'control arm, to carry the rest of the main 5mm shaft.
This combination of two tubes and the 'steering arm' - which is 50mm total length - all forms a very solid 'tube system' for the shaft.

The TRICKY parts of all of this is that TWO of the 'flats' used to lock the Control Arms onto, have to be 'matched' so that the two Stabilators are ALIGNED accurately once they are all done up. The center Control Horn and ONE Stabilator side can be low accuracy, but the OTHER Stabilator must match off the first Stabilator. This will require 'tuning' of that Stabilator's "flat".
If really need be the Stabilators could be EPOXIED onto the shaft, which is a way to 100% guarantee they are aligned and LOCKED like that forever! But I would rather have them as removable.

Last edited by PeterVRC; Jul 23, 2018 at 05:44 PM.
Jul 21, 2018, 07:53 AM
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Wing - Ailerons and Flaps

For the Ailerons, I removed the tape hinging and re-faced the Aileron and Wing with Balsa wood. This was to allow making a radiused Aileron hinge joint, so the Aileron Round Pin Pivot Hinge can be set to the Centerpoint of the Radius and thus allows the Aileron joint face to follow that arc as it is moved, thus keeping the joint always 'closed'. And having no "V" like the more common 'simple' face method has.
This still needs (?) something to cover the small amount of gap that remains, and top do that I will add some 0.4mm Acetate strips onto the Wing and they continue on over to the Aileron face, thus totally covering that remaining gap.
It is a bit of 'overkill' I guess, but it means the Wing will remain 100% 'intact' as a fully clean surface at all times.
The Flaps may also get this Acetate overlap on the Upper Surface, to assure it is all a clean fit too - though they are a fully clean fit when Retracted anyway really.

For the Flaps, I used the Offset Hinges like '4Stripes' did.... except I did make a slight boo-boo with those.
If they are set to be ABOVE the Wing surface then they will cause the Flap to 'drop' as it changes to an Angle and form a Fowler Flap type state. But I only had mine a fraction above the Wing (1mm) and thus it had virtually NO Drop, which means no Fowler Flap type action. I hadn't planned their installation properly!! But as it turns out, if you do not 'round' the Flap face, to fit into a receiving round in the Wing, then the Fowler Flap can't operate properly anyway. The Flap face needs that Round so the airflow CAN come in from under the Wing and cleanly continue to run over the top of the Flap. I had decided that rounding process was too hard to do in a decent manner. Not impossible, but just too much work to get it right.
Thus the Fowler Flap 'error' I had did not really matter anyway.

The Flaps do actually Drop a bit.... who knows what the airflows coming from UNDER the Wing to OVER the Flap will do now. But I did round the Flap face a BIT so that it is a better flow path for it.

Last edited by PeterVRC; Jul 22, 2018 at 08:55 AM.
Jul 21, 2018, 08:01 AM
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Wing - Aileron & Flap Servo Boxes

All servo used in the BAE Hawk will be in Servo Boxes, to allow easy changing of Servos. Thus the Wing gets 4.... 2 for Ailerons and 2 for Flaps.
These were 3D Printed and each has a 'square' cutout in the Wing where the box is epoxied into. The Cover Plate is screwed on and holds the servo tightly under it. It is also all set up so that the Cover Plate surface ends up flush to the Wing surface.
(some earlier pics have grey cover plates, but it actually has black ones for all Wing Servos)

Last edited by PeterVRC; Jul 22, 2018 at 08:56 AM.
Jul 21, 2018, 08:10 AM
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Wing - Linkages

All BAE Hawk linkages will be dual Ball Joint, with custom made pushrods for those. 2mm pushrod with threads added for both ends, lengths to suit their installation.
HobbyKing has some really good, and reasonably cheap, 'medium/small' sized ball joint sets so I had bought up quite a lot of those. They are good fits with no freeplay. They are ideal for 90mm sized aircraft types. The 2mm pushrods were also from HobbyKing, 300mm (?) but come with only one end threaded. A cheap 2mm die allows making the threads on any length pushrods you might need.....

For the Aileron, to give strong support to the Control Horn in the Aileron, it has an 80mm 5mm x 1mm Carbon Fiber Strip running across the Aileron at the mid point of the Control Horn. Thus the control Horn has a slit cut into it so that it fits onto the Carbon Fiber Strip and is epoxied into the Aileron. Therefore it has 80mm of support across the Aileron....

In the Flaps, which use the Control Horn that is built into the Offset Hinge itself, they get a full length carbon Fiber Strip of the same 5mm x 1mm of the Aileron. This is just to ensure the Flaps STAY as flat Flaps at all times!


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