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Here is the first installment. Progress is slow at the moment due to various issues, but she'll be ready.
PE Norman was a craftsman of the highest order and hismusic instrument making skills are put to excellent use in forming a ply shell for this free flight aircraft. I'm doing my best to do justice to this design that is based loosely on the Gloster Javelin. PE Norman made his own fans, that did work well and produced sufficient thrust for flight on the very meagre power outputs of the model engines of the day.
I'm diversifying here in that I will be using a commercially available EDF fan and motor combination which will give significantly more thrust needed to cope with the extra weight of the RC conversion and EDF system.

 






Edited By Ady Hayward on 31/01/2012 23:16:48

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Hi Ady,
 
What a fantastic build idea (excuse the pun) I did mess around with the original PE Norman concept in the 70's with a ply hub based fan with fibre board blades but they were trashed due to not fully understanding the concept at the time. What I still have from the time is a nylon fan developed and produced by Veron.
 
If you decide to go down the IC route as per original give us a shout, the fan is doing nothing so your welcome to it for the vintage build. A 1.5 to 2.5 diesel is about right for power, but spinning this thing up on a 2.5 cc racing diesel is quite scarey. I've run it up on a fok 25 and a Russian rear induction racing motor, and you want to be well behind it.
 

 
Cheers,
 
Chris.
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Hi Ady,
 
What a fantastic build idea (excuse the pun) I did mess around with the original PE Norman concept in the 70's with a ply hub based fan with fibre board blades but they were trashed due to not fully understanding the concept at the time. What I still have from the time is a nylon fan developed and produced by Veron.
 
If you decide to go down the IC route as per original give us a shout, the fan is doing nothing so your welcome to it for the vintage build. A 1.5 to 2.5 diesel is about right for power, but spinning this thing up on a 2.5 cc racing diesel is quite scarey. I've run it up on a fok 25 and a Russian rear induction racing motor, and you want to be well behind it.
 

 
Cheers,
 
Chris.
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Hi Bill, Chris.
Many thanks for your posts. I do hope to do justice to this design from one of Britain's D/F pioneers. Many thanks Chris for the offer of the fan. I too have one of those Veron "IMP" impellers. I first fitted it to a Veco .19 glow motor in 1978 that was to power an O/D delta. Blade stretch was quite alarming and I decided to leave it well alone. It ended up fitted to a speed 600 brushed motor which
was replaced for this project by a 4800KV EDF motor and on test was found to still stretch alarmingly and produced far less thrust than the 55mm9 Fan unit.
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Hi, Some progress was made over the weekend. The inlet inner ducting has been done. 3/32" balsa was used to allow further sanding of the inside to achieve a smooth duct surface. The 2mm ply wing mounting tongue (originally the ic motor mount as well) will go in later once the duct is sorted. the forward section of the duct has the collar to which the duct wall fixes gives thickness with wich to form the inlet lip. The fan unit locates in to the rear duct former to form a better seal, and helps lock the fan in position. The rear ducting will be done in similar fashion.
 


 
 




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Hi Chris.
Many thanks for the compliment. PE Norman was one of the great pioneers of ducted fan, and a master of aeromodelling in all its guises.We can still learn a lot from his works and building techniques. I'm learning new things with this build too. All being well it will progress at a quicke pace now the tricky bits are done.
 
Adrian
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The wings are quick and easy to build. The changes to the structure from original thus far is to increase the rib thickness from 1.5mm (1/16" ) to 2mm (3/32" ) to give more support and the addition of a second sub spar at the rear of the wing where the reflex was added which will form the new wing trailing edge, and elevator leading edge.

Lower TE sheet and spar

Spar cuts marked

Ribs added to the spar and TE sheet

Leading edge fitted

Elevon hinge spars and tips added

Edited By Ady Hayward on 17/02/2012 23:14:21

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I'm retaining the "Knock off" wings as per the original, as that was a particular of the design but having small screws to lock them in place when fitted. There will be a servo to each elevator as I may elect use the surfaces as elevons if the tailplane doesn't work too well.

wing tongue box structure

Wing tongue box snug fit

Location in wing

Edited By Ady Hayward on 20/02/2012 13:40:39

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So far so good. The tailplane is assembled. I did wonder whether an all flying surface was feasible, but opted for the simple solution and a false spar added to create the elevator. The pushrod will be 18 or 20swg wire in ABS tube passing through the fin core. The original had 1/32" sheeting for the leading edge and 50% of the way back, but I'm opting for light 1/16" sheet over all the fin to beef it up a bit for the inevitable ground loops on landing. At the moment it is looking like there will not be any c/g issues. Bare airframe weight of the model as seen is 226g (7 7/8oz)

Tailplane build 1

Tailplane build 2

Tailplane build 3

Fin

1st assembly

Ady

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some more progress. The lower fuselage shell is fitted, and the access hatch is yet to be fitted. The fin is sheeted and the elevator servo installed in the fin base which will have a short external pushrod to the elevator. The aileron (Or maybe elevon) servos are fitted to pockets in the rear of the fuselage allowing good access for change out, and close to the ailerons to have a short neat linkage. This saves any complications with the wing build.

The next items are leading edge sheeting for the wings, fuselage hatch and the cockpit section which will house the 1300 3s LiPo.

Fuselage shell complete

fan access hatch

aileron servos

elevator servo in fin base

servo to aileron coupling

Ady

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  • 2 weeks later...

Well, the end is in sight. After much head scratching i came up with a solution to modifying the nose section to take a Lipo. It is widened by 20mm and can now house a 2200 3s, although it is intended to fly initially on a 1300 3s with which it balances just nicely where recommended. I also hinged the fan access hatch and faired in the wing roots, so apart from the inlet lip and some fairing around the top of the front fuselage she's just about ready for sealing and covering in silk.

Its hard to believe this design was a free flight model.

Closed hatch

Open hatch

Nose section done

Nose section done underside

Ady

Edited By Ady Hayward on 04/03/2012 21:09:03

Edited By Ady Hayward on 04/03/2012 21:10:31

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The intake lip was formed using preformed leading edge with sawcuts to aid its bending around the intake. A lot less trouble than using sheet balsa and sanding it backto shape.

A few years since I last covered a plane in a fabric. It was easier than I was expecting and the silk went around compound curves better than I thought it would. Once the weave is orientated correctly it works well. The fuselage was first as it is a simple shape, followed by the tailplane and the flimsier elevator. No problems thus far so the wings shouldn't be too much trouble. (Famous last words).

Preformed leading edge for duct

Covering the cockpit

Inner edges covered

Tailplane underside covered

Top side covered ready for trimming

Cockpit, tailplane and elevator all covered

Ady

Edited By Ady Hayward on 10/03/2012 23:35:10

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Hi Chris,

Thanks for the compliment. The silk was purchased from Beckford Silk http://www.beckfordsilk.co.uk

I bought one of the cheapest plain weave at the lighter end of the weights offered, but there is an enormous variety of weights, textures and colours for you to choose. The "Grain" in the weave is quite marked and by folding it over on itself and pulling the fold taut, you can see by the diameter of the fold which way is tightest and therefore the run of the grain. This then runs along the span or length of fuselage. It was applied after coating the whole structure with dope, and then using dope around the edges first pulling it tight and keeping an eye on the weave to keep that all in alignment. When both sides are done was then water shrunk, allowed to dry naturally and then doped with 50/50 mix of dope/ cellulose thinners.

Ady

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Really cracking on now. The wings are tricky, but were not too bad to cover. First the frame was doped and sanded then doped again. The lower surface was put on first with the main weave running span wise. The silk was applied dry and attached with dope around the edges only. When dry the surplus fabric was trimmed off with a new scalpel blade and the edge sanded down with some fine wet n dry. The top covering was applied in the same way making sure the weave was aligned as the undersurface with no wiggles in the weave lines. When dry the edges were trimmed off and sanded as before. The wing was then sprayed with water mist to wet both surfaces and hung to dry naturally. No warping was found so the application of the silk was quiite good....Yay!

when totally dry the whole wing was doped with 50/50 mix dope/ thinners and pinned down overnight. Hopefully it will be tight as a drum and warp free.

Underside dry attached to the frame

Edges sanded down prior to top surface going on

Top surface dry attached to the frame

Water shrinking the silk covering

Doping both surfaces and pinning down overnight

Ady

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The last bits of silk covering have gone on to the fuselage, so all that is left is to hook up the controls and add trim colour(s) using coloured modelspan tissue. The plane at this time with a 1300 3s Lipo weighs 1oz (30g) more than the free flight version, and 6oz (approx 180g) less than the contemporary RC version.

Edited By Ady Hayward on 15/03/2012 13:24:08

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Andy, looking at the pictures, it looked that there was a Venturi, for no obvious reason. If so, what do you think it is meant to achieve?

As a model, it looks well constructed by yourself.

It will be interesting to hear of the flying, which cannot be far off now.

Edited By Erfolg on 15/03/2012 16:24:47

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Hi Folks.

A good day today. The maiden flight went ahead and she's still in one piece. Hand launching is a little tricky with the wide fuselage, so launching via the nose section proved best. There were a couple of failed launches which fortunately did not cause any damage despite some extreme attitudes/ arrivals and in the air she handles acceptably. It does have a distinct wing rock at low speed and will spin without provocation if slowed down with any power applied, but thankfully comes out after a couple of turns with the throttle closed. loops and rolls are possible from level flight and she has a good turn of speed considering the bulky fuselage and being driven by a 55mm fan on a 1300 3s lipo 25c. Landing is a bit faster than I would have preferred, but needs the speed to reduce the wing rocking and keep away from any tip stalling at low level. In all I'm pleased with the result, and just need to tweak things a little to improve the low speed handling.
Here's a couple of pics from today.

Ady

Edited By Ady Hayward on 24/03/2012 19:01:30

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