quorneng

Well I thought about it and decided to go ahead and build the final Sea Hawk version the P1081 which had a 'straight through' exhaust.
After all it started out as the second P1052, the swept wing Sea Hawk. so only the rear half of the fuselage was actually different as this picture shows.

Obviously taken just out of the shop as the new tail is still unpainted where as the remainder is still in the prototype very pale green/blue.
The new fin and tail now look remarkably Hunter(ish)!
I used the 3 view to create the necessary fuselage plan.

The inlet side of the duct is unchanged but of course the exhaust part is much longer.

With such a long duct it seemed logical to use it as a 'spine' and build the fuselage round it rather than attempt to 'sink' it into a half fuselage shell as I did for the much shorter bifurcated duct.
With the formers cut out and glued onto the duct the first pair of planks go on.

The planks are long and there will be quite a lot of them!

quorneng

After lots of planks and pins the fuselage looks like this.

Areas of the skin have to be left open to allow the elevator servo wires to be fed through the formers.
Next is the wing root fairings.

This is the top view but as before parts of the underside have to left open to run the aileron servos as and when the wings go on..
It will be interesting to see if the straight through duct gives a performance improvement over the aerodynamically identical P1052 with its shorter and lighter bifurcated exhaust duct.
I suspect in such a light weight installation my guess it will be 6 of one or half a dozen of the other!

quorneng

Still plodding on with the Hawker P1081
As the tail plane is severely swept it made sense to use two elevator servos.

Although only tiny 3.7 g but being mounted in the tail plane means their weight is a long way back.
Combined with the long printed exhaust duct it may be necessary to mount the battery further forward than in the Sea Hawk.
The wings are a direct copy of those used for the P1052.
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Of course with the elevator servos mounted symmetrically meant that one would have to have a servo reverser inserted before the Y lead.
The individual servo wires go down through the fin. There is sufficient room around the exhaust duct to add the servo reverser and connect the Y lead..

The single elevator wire is then passed through the fuselage formers to the cockpit.
The skin can then be made good and the fin completed.

Next to add the wings.

solentlife

Question .... did you find the reverser work OK ? I tried one while back and the pulses made servo step rather than rotate smooth. I ended up mounting the servo 180 to save rewiring. Later models - I used 2 ch's on RX.

quorneng

There are not quite as many step on the reverser as with the rx driven servo but not that significant. My reasoning was as it is working an elevator in conjunction with a good servo hopefully the net effect on pitch control should not be too noticeable. We shall see.

I have has a servo reverser make a mess of a 'stand alone' self righting gyro system where a small gyro correction had no effect on the servo only to be followed by a massive movement when the gyro correction input got large enough to 'wake up' the reverser by which time corrections were needed on the other axis too so the result was the 'self correcting' was rather erratic. Like you, reversing the linkage geometry and removing the reverser cured it.
A gyro works best if it can achieve a small but virtually instant effect.

quorneng

Still moving on.
The wings go on.
A bit tricky as the aileron servo and its wire is already in place so it has to be threaded through to the cockpit area as each wing is glued on one at a time and left to dry for 24 hours

As with the Sea Hawk and P1052 the wing skin is a simple butt joint. The relatively thick 5 mm top and bottom wing skin gives a sufficient glue area.

Hopefully I have run all the wires in suitable positions through the cockpit bulkhead for the ESC and Rx.
Nose section next.
Should be easy enough as it is identical to both the previous ones. .

quorneng

The nose section goes on.

One advantage of using 3D printing, just print another nose cone!
Quite a bit of lightweight filler for the various skin imperfections acquired in the soft XPS during the build.
The P1081 like other Hawker prototypes of the period was painted in a very pale green/blue so the first task was a white acrylic as an undercoat to cover the grey XPS.
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The acrylic is quite thick so it does a good job of filling any very small gaps in the planking.
The canopy 'hatch' is skinned in 3mm Depron but not quite complete..

quorneng

The paint scheme is simple. It same colour all over, two thin coats of acrylic and a light spray of acrylic lacquer. The slight gloss surface means the self adhesive roundels actually stick.

There is also a yellow P in a circle on the fuselage and its number VX479 in large black letters underneath.
The maiden. It benefitted from a Lemon "stab" receiver.
I took the opportunity to picture the three together.

Sea Hawk, P1052 the swept wing Sea Hawk and P1081 the swept wing Sea Hawk with straight through exhaust but all still using the same RR Nene centrifugal turbo jet.
That just leaves the Hunter as the final piece in the development tree.

Don Sims

Exceptional work and it's great to see another one flying.

quorneng

Don
hank you for the kind words.
I must say this is the first time I have built 3 planes, immediately one after the other, each with some identical features and all to the same same scale. It is interesting to compare their flight characteristics but being 'one piece' planes they do take up rather a lot of storage space.
The really worrying aspect is I still have quite a bit of 5 mm XPS left!