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Oct 05, 2021, 05:17 AM
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Hawker Hunter P1067


Having built a Sea Hawk, the P1052 Swept wing Sea Hawk and the P1081 'Straight through' Sea Hawk all to the same scale.
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I just had to build the ultimate bit of the line of development, the P1067 Hawker Hunter also to the same scale and built in the same way.
It seemed logical to build the prototype Hunter which was painted in the same very pale blue/green as the P1081 and was very 'clean' not having the aerodynamic 'additions' that were added to the production versions.
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Some calculations showed that at the desired scale the Hunter exhaust nozzle would be 90% of the FSA of a 50 mm EDF and I just happen to have a spare one!
As before with such a long printed EDF duct this would be made first and the fuselage then built around it.
The EDF with the multiple section exhaust and nozzle.
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The exhaust nozzle is printed so it also forms the last part of the fuselage skin.
With the bifurcated inlet section included the duct will be about 1/3 longer still!
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Oct 06, 2021, 07:43 AM
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Rudi's Avatar
Cool Project, will watch it very close

thx for sharing

cheers

Rudi
Oct 06, 2021, 11:34 PM
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AntiArf's Avatar
Yep neat project. It's in the 1953 Farnborough airshow, quite possibly the best year of all IMO, and has the supersonic boom. I've watched every year I could find on You Tube.
Oct 09, 2021, 06:50 PM
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The full length duct.
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Next to add the formers. From the inlets back wards they are basically circular so not to difficult followed by the first few planks.
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Hurray! I am actually beginning to build a plane!
One advantage of building over a rigid spine is the planking is all done 'free hand'.
Each plank is very long and narrow and has to be shaped a bit toward the rear where the fuselage thins down.
The Hunter has a spine that runs on top of the fuselage from the base of the fin to the cockpit so the elevator servo wire will run inside it.
This could take some time.

Here you go 1953 Farnborough. The Hunter is 7:45 to 8:55 and includes the bang!
Farnborough Air Show 1953 (12 min 26 sec)
Last edited by Quorneng; Oct 09, 2021 at 06:58 PM.
Oct 11, 2021, 11:19 AM
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The planking round the duct more or less complete'
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The bit missing at the from is for the substantial fairing after of the cockpit. The bit at the rear is for the lower part of the fin that also carries the tail plane.
The fin base added including part of the spine with the elevator servo wire running through it.
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The tail plane and fin (it will have no rudder)are next.
Oct 14, 2021, 06:04 AM
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Moving on.
The tail feathers added.
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As the hinge lines are at such an acute angle it needs a 3.7g servo for each elevator. They are connected by a Y lead inside the Hunter's trade mark 'spine' that runs from the base of the tail fin to the cockpit.
As with the other Hawkers the wing is very simple, just a top and bottom skin pulled over two tapered shear webs. All in the same 5 mm XPS.
Each surface is sanded on the inside to give a fine trailing edge.
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It does require a lot of clamps to hold everything until the glues sets indeed so many that I can only build one wing at a time!
The Hunter wing uses quite a bit thinner section than the Sea Hawk so it is probably getting close to the limit of what is possible with unreinforced XPS.
It will rely on the planes overall light weight (for an EDF) to keep the wing stresses sufficiently low.
Oct 20, 2021, 07:58 AM
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As with the other XPS built Hawkers the wing fuselage joint relies on the large area of the foam skn to provide sufficient strength. The danger is the Hunter has a thinner wing section and slightly greater span.
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However with a slightly flexible swept wing any bending tends to induce washout so reducing the bending stresses. It almost becomes 'g' self regulating but I doubt I shall be exploring any high load manoeuvres any time soon.
Once the 'Technicqll' glue has set hard (24 hours) it will be ready for the nose section to be glued on.
The construction of the nose section itself is similar to the previous first as a half shell over the plan and then lifted and completed free hand.
The substantial printed nose cone proved to be a bit tricky.
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No problem printing an elliptical cone except it has to be from a circular base. Unfortunately the Hunter nose base is itself elliptical and not symmetrical either!
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The printed cone is fairly flexible so I judged if its base circumference was exactly the same as the circumference of the nose it should be possible to 'distort' the nose cone by hand whist the glue set.
It took a couple of attempts to get it exactly right but it worked.
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It now actually starts to look like a Hunter.
Oct 20, 2021, 04:38 PM
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nvd07's Avatar
Hi I have looked at all threads, for the whole series, with great interest: great building skills and use of various materials and construction techniques!

I have a question about the printed nose cone. I do understand the bit about circumference needing to be the same. ( In fact I am considering 3D printing a replacement cowl for an old 'GreatPlanes extra 300' and was thinking that , rather than an equal width and height at the firewall, what was really important was to measure the circumference and to replicate it. )

However why do you mention that the 3D printed cone 'has to be from a circular base'... is it a deliberate choice for simplicity. or is it a limitation of the CAD software, or else ?
In some CAD software the A-A shown above , could be obtained by breaking it down into just two conical curves (1 for first quadrant, another for 2nd quadrant, with tangency constraints. then both mirrored along the vertical). This could then be lofted into the nosecone... Granted, my own attempts at conical lofting over the entire length of a fuselage had mixed results; however just the nosecone would seem easy , unless I am missing something...
Oct 20, 2021, 07:34 PM
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nvd07
Yes it is primarily a CAD limitation but when done as a single 'mathematical' sketch it is quick to do. The resulting 'vase' printed nose cone is a very light single wall structure so has to be considered as sacrificial in anything but a perfect belly landing.
At the time I was more concerned to get the Hunter built. Generating the EDF duct was already time consuming enough.
Oct 23, 2021, 06:44 PM
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With just the canopy as the only hatch means it a bit cramped inside. For CofG reasons the battery had to go forward which left a bit more room.
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The ESC is in the left hand cockpit wall with its fingered heat sink poking through into the air stream.
The Lemon stab radio has to be accessible to allow the gyro gain to be adjusted if required leaving just enough room to slide the 1800 mAh 3s into a box in the nose.
Painted with not quite the correct size decals.
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This picture does rather show how 'slim' the Hunter is compared to its immediate predecessor the P1082.
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Just waiting for the right weather.
Oct 25, 2021, 04:32 PM
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turbonut's Avatar
Very nice..
Latest blog entry: In flight
Oct 27, 2021, 02:39 AM
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Rudi's Avatar
Quote:
Originally Posted by turbonut
Very nice..
Agreed !!!
Oct 29, 2021, 05:43 AM
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Thread OP
A slight up date.
The Hunter flew quite nicely but on a flight specifically to be videoed this happened.
Hunter crash (0 min 40 sec)

Still not sure why it cut out but the damage was quite severe. It appears the more brittle XPS foam transmits shock rather than energy absorbing crumpling as does Depron.
07Oct21 crash damge (0 min 39 sec)

The nose section was completely destroyed so simple to replace but of more concern were the major cracks where the wing joins the fuselage and the complete rear fuselage break. The major duct break was repaired with a printed sleeve over the joint but the duct was split elsewhere which necessitated opening up a portion of the fuselage to apply several printed patches to cover the splits.
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Anyway with a new nose it all went back together well enough.
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The first bench run up identified a further problem. The duct was more severely damaged than at first diagnosed resulting in it locally collapsing and severely restricting the inlet.
Hunter duct failure (0 min 11 sec)

This required yet more fuselage areas to to opened up to apply the necessary patches and strengthening.
With 100/100 hindsight I probably should have simply scrapped the airframe and built another!
Anyway it is all fixed.
A short flight in very windy and turbulent conditions for a light weight foamy EDF but a safe 'no damage' landing.
The Hunter in a wind! (1 min 51 sec)

You can tell how strong the wind was by the different is perceived speed between into and down wind.
I shall have to wait for some calmer conditions to make a better video.

I was perhaps fortunate that the three previous Hawkers all managed to fly repeatedly without any serious damage otherwise I might have had this problem earlier.
Oct 29, 2021, 12:56 PM
BFMA #13, aka Rogue 13
mongo's Avatar
so, the reason for the earlier "cutout" was???
Oct 29, 2021, 02:26 PM
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I still don't know.
I have run a full power ground test for considerably longer than the failure point in the video to check it was not a ESC cut out. In addition the same Rx and Tx were used in the three earlier Hawkers with no problem over quite a few flights.
I suppose a bad connection was possible but the severity of the crash rather ruled out any detail diagnostic testing.
It works now ok.


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