My next EDF? (or rather EDP)

[quorneng]

My Depron Skyray flies rather better than I had dared to hope so I thought I would try a rather more conventional layout plane, albeit a rather unusual one, in that the full size was never completed.
The impressive Hawker P1121 (actually the P1122 version intended to fly at mach3!)
   
This was just a full scale mock up. Actually its not white but pale duck egg blue!
The reason for choosing the mach3 version is that it was intended to use the huge DH Gyron turbo jet so the fuselage has a generous cross section allowing quite a big fan/prop to be installed.
Built in Depron like the Skyray with the same 4.5 diam ducted prop the span comes out to be 30".
The biggest problem is the difficulty of enlarging the belly intake to match the prop area. The twin side intakes on the Skyray could be significantly altered without dramatically effecting its appearance.
I may have to adopt some form of cheat holes in the upper fuselage surface to generate the necessary inlet area.

Although work on the prototype had actually started, the project was cancelled by the infamous 1957 white paper.
I doubt it would have ever achieved mach3 and certainly not with the Gyron which had a poor fuel consumption and never delivered anything like the anticipated thrust at supersonic speed but like many Hawker designs the P1122 certainly had the looks.

[Tony Smith]

Interesting, does make you wonder where General Dynamics got the idea for the F16.....

Perhaps Duncan Sandys gave the blue prints away.....

[quorneng]

What is even more remarkable is that the prototype was started with Hawkers own money (rather than the ministry's) so it was not chopped up like TSR2 and more recently the MR4 Nimrod.
   
The bits still exist and are stored (but not displayed) at RAF Cosford.

Although the intended Gyron was not successful the 'standby' engine for the super sonic version was a proposed reheat version of the much more fuel efficient Olympus although at the time that engine was slated to be cancelled as well!

With the benefit of hindsight an Olympus version could have proved to have been a really successful fighter bomber with the possibility of a "super cruise" performance long before anybody else.

[solentlife]

I was going to say about the similarity with F16 as well !

The TSR2 ... as far as I know - there is still one standing on an Airbase under guard ...
Much of the development work and innovations such as Head-up displays ... ground tracking navigation etc. was in fact handed over to US.
I had a friend that had worked on Electronics with TSR2 ... testing gear in the Canberra and 2 seat EE Lightning. He always said that literally one morning they were all told to clear their desks and ignore 'others' they would meet boxing up files etc. He said they did not have UK English accents !!

As we all realise ... UK was not financially able to maintain projects as this, despite the fact they were worldbeaters. The EE Lightning in fact was 'masked' as a development on from an existing a/c so it wouldn't be scrapped ... funding being the company itself and a huge gamble ...
Even to Concorde ... Uk and France simultaneously trying to develop a supersonic passenger airliner ... then when detente came about - joining forces to bring Concorde to flight.... without that collaboration - no doubt money would have run out and it would have been consigned to the ''what-ifs" ....

It's a shame that we have the ideas to push forward fighter / bomber a/c design - but no longer the finances and determination to achieve. Harrier.... Hawk ..... are good examples and not to forget that serious part of the Aerobus and Panavia co-operations had UK expertise.

We watch the UK military decline, despite still being involved in conflicts. What is future ?

The Lynx helicopter still holds the speed record as far as I know ... the Apache attack helicopter had it's weapon and payload improved by fitting RR engines instead of the US version for Afghan theatre ... but then we go and spoil it all by cancelling any further development of Harrier ... even though US version will be continued and developed on etc. etc. Please don't tell me we will BUY Harriers from USA ?

Sorry to get on a hobby-horse and rant ...

Back to EDF ........ looking fwd to see the model !!

[quorneng]

I was given a nice 3 view drawing of the P1121 with lonts of fuselage sections, unfortunately it is copyright so I cannot show it here, nevertheless the build continues albeit rather slowly.
Scaled to fit a 4,5" prop inside the fuselage the wing span comes out at 30". With the Skyray a 4,4" prop gave 36" span which rather shows just how big the P1121's fuselage was.
The wings have 5 spars, 1 load bearing and 4 spacers, but here are no ribs. To save weight there will also be no ailerons and I will use the all moving tailplane as elevons.
The main spar.
   
1/32" (0.8mm) hard wood flanges on a 3mm Depron web. The spar tapers from 18mm at the root to 8mm near the tip and the flanges also taper from 6mm wide to 3mm at the tip.
The spars added to the lower skin.
   
The top skin is added 'freehand' drawing the skins into a scale symmetrical wing section with a thickness/chord of just 5%.
   
I am hoping the completed model will a touch lighter than the Skyray and it will need to be with such a thin supersonic wing section!

[quorneng]

I have been making slow progress with the P1121.
The wings and tailplane (all moving) were relatively simple.
That long, long fuselage was always going to be the hard bit.
To make life a bit easier I chose to build it in three sections and started with the centre.
All 3mm Depron former and plank job and to make life a bit harder again the formers have very little 'meat' on them as the duct is so large.
The LH half formers
   
First the duct is planked on the inside.
   
The half duct complete. Note the balsa reinforcement to the former that picks up the wing spar.
To add stiffness to the structure the wing is added.
   
Note the anhedral.
The formers of the RH side of the fuselage were then fixed on and the duct completed.
   
The centre part of the fuselage does change section along it length but relatively slightly (from a true circle at the rear to an oval).
The nose section with the ventral duct was alwys going to be much more complicated.

[Tony Smith]

Most excellent.....Depron fettling....

[quorneng]

The nose section was built in one piece - vertically following the technique I used on my Bachem Natter.
   
The underside of the forward fuselage was made concave to increase the area of the chin duct although the side profile is still to scale.
   
Even with this 'tweak' the area of the inlet is only about 70% that of the duct so two 'cheat' holes were added where the weapons bay doors were mounted.
   
The final result is in effect a trifurcated inlet duct.
   
The tail section is relatively simple as the duct is a constant section so here it was formed by a single 2mm Depron sheet wrapped round the plastic sewer pipe "plug".
   
The next problem is to see if the sections actually match up to each other and then to join them trying to avoid a "banana" fuselage!

[quorneng]

The original had an all moving tailplane but it would save weight and complexity to turn them into elevons as well.
Each elevon is similar in construction to the wing but rotates around a fixed glass fibre tube spar.
   
The fuselage could now be joined together.
   
Building a fuselage 'inside out' like this does make installing the RC quite a bit easier.
At this point I added some additional formers on the underside of the fuselage to further support the skin where it would be held for hand launching.
   
The tailplane is mounted on a bulge under the fuselage and it was just big enough to hold the elevon micro servos.
   
Finally the fin was added.
   
It now started to look like a plane.
The next problem was to establish where the motor and prop would have to go to counter balance the weight of the battery such a long way forward in the cockpit.

[quorneng]

The first task was to create the motor 'pod'.
   
With the plane supported at approximately the CofG (slightly ahead of the main undercarriage leg position on the original) with the motor placed at the widest point of the 'area rule' in the fuselage the battery needed to be placed just behind the cockpit rather than in it.
   
I could have mounted the motor further aft to get the battery in the cockpit as originally envisaged but I felt the motor with its close fitting prop needed as rigid a support as possible. I was also concerned about the inertia of having the two heaviest items at the extremes of the fuselage, particularly with such a short tailplane moment.
To actually mount the motor required the fuselage to be chopped in two!
   
Actually not that difficult in Depron.
The motor mounted in the fuselage rear section.
   
At this point I weighed the cables running from the battery to ESC and to the motor and got quite a shock. They weighed more than the motor and prop or just over 10% of the planes estimated total weight.
I needed a plan B!