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007's 'Little Nellie' MK II


Richard Harris
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Remember when you first starting flying RC aircraft? 9 times out of 10 the first model most people wanted to fly was a Spitfire but is totally impractical as a trainer. I was exactly the same and have never got round to building a Spit.
The same thing happened when I started messing with these Autogyros, for me I wanted to build 'Little Nellie' from the bond film 'You only Live Twice'. Again not the best autogyro to start with as it has a 2 blades and only a fin.
Many crashes later and countless rebuilds and experiments I got a 2 bladed fin only model autogyro to work. I had a lot of help from a German friend called Jochen regarding the aerodynamics and set up, sadly he passed on at the beginning of the year, so this model will be in his memory.
This model was built the end of last year but due to my stupidity I almost completely destroyed it, so with some of the bits I have started a new model of 'Little Nellie'. It's around the 1/4 scale mark and built around drawings that Wng Commander Ken Wallis has sent me, he is one of the most helpful gents I have ever met and is always keen to help us modellers out
The original was a little bare so this time will be armed, these parts will be removable as I am unsure how it will effect the flight characteristics. I will just add each set of weapons and compare as I go along.
So this will be a 'ground up' rebuild with a lot of mods I will post photos as I go along, I hope it is of interest?
 
To those who have never seen the clip from 'You only Live twice' here it is.
 
 
A few photos of where I am at.
 
The main frame is made from 10mm carbon fibre tube, aluminium inserts are epoxied into place where the frame is drilled through. The crutch is aluminium tubes and sheet tig welded together and doubles up as a servo mount.



Rich
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Alan,
Micro Mold made a kit way back in the late 70s early 80s, but this utilised a swash plate for roll and pitch control . It wasn't very scale looking and today we have servos that can produce the torque needed to replicated the direct control to the 'offset gimble' head that Ken designed and patented.
 
The 'real thing' is powered using a 2 stroke 4 cylinder Mculloch drone engine and is positioned quite a way back past the mast. I have machined up some spacers to get my electric motor into roughly the correct position, I have to make a new mount but it will be adjustable both up and down and side to side to counteract prop torque and get the thrustline in the best position. Unfortunately the height of the motor has been altered due to the size of props we use for models.


The triangular motor mounts are made from fibre glass sheet, mounted off the corner of these are the out stays to the main UC legs. The original has these sprung but mine will be rigid.
 

Rich

Edited By Richard Harris on 25/05/2011 11:17:08

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Cheers Tim,
I do prefer balsa bashing though!
 
 
 
Made up the new motor mount this morning from GF plate, the structure is stiffened up using aluminium rods (3mm TIG wire with the ends flattened off). Also made up a foam tank as the original was a touch on the 'broken side'.
Servos are Tower Pro 946's as these have something like 12kg of stall torque, cheap but work fine. These are mounted to a GF mount which is bolted to the the aluminium crutch. Mounted off the top servo back plate outer screws are the seat posts, these are just bent up alloy sheet and makes the servos non flexing when tightened up.
It is surprisingly rigid at this stage.
 


 
 
Rich
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I made up the new head at work yesterday afternoon the original was wrecked!
This is directly connected to the 2 servos in the above picture and is set up in an elevon mix, angle it to the left and it will roll to the left, tip it back and it will slow the autogyro down etc
The 'tee' piece is made up from 6mm duralumium sheet and is free moving on a metal universal joint picked up from my LMS ( I think it was off a model cars drive shaft).
To this a a machined silver steel shaft which screws into the 'tee' piece with a lock nut to hold it rigid. The rotor hub is made from 1.6mm Glass Fibre sheet with two 8mm bore flanged bearings top and bottom.
The reason for using Glass Fibre sheet is that the blades need to flex up one side during their rotation. The advancing blade (the one going forwards) flaps up which alters its incidenece and reduces its lift, as it is retreating (going backwards) it straightens out creating more lift. This evens things out naturally and is called dissymmetry of lift, it gets quite complicated and to be honest goes over my head a bit.
If the hub was rigid it would just roll to over to the side of the retreating blade, being pushed in that direction by the blade going into wind.
What you end up with is basically a disc that is neutral in pitch, free wheeling with the air going up through it....like a sycamore leaf.
The real thing uses what is called a teetering head (American for 'see saw' I believe?) copying this in a small model is not an easy thing to achieve...something to do with Reynolds numbers. So I have cheated and taken the easy 'tried and tested ' method and gone with a simple flexi plate.
Sorry for going on!
 
 
A few photos of the finished head, the real thing and the housing I have made from pink foam that will wrap around it.
 




Rich
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Just a few more pictures before I head off to work
 
I managed to salvage and repair the rudder, this is made from 2 laminates of 6mm thick depron epoxied together, sanded to shape with a skin of epoxy resin. Spray painted with some solar trim added.
The fin is new and is made from laminates of balsa, hardwood points added for the alloy brackets which will hold the mounts for the flame throwers covered in solar film.

The foam tank was layered up in tissue and epoxy resin, the foam core was removed with thinners and lotttttttttttts of filler added before sanding down and spraying. This slides down the boom and 'clicks' into place, the slot on the bottom is narrower than the mast carbon tube. The hole on the top at the rear will have a rubber grommet inserted, through this the motor wires will run. The ESC is situated inside the tank when full assembled.


The fuselage plug was again made from pink foam and covered in tissue and epoxy resin with a lot of hard work to get. Molds have been made from this but all didn't go to plan as I didn't apply enough release agent (first attempt at fibre glassing). The original fuselage was again damaged but I have managed to repair it, it is in the process of being painted and I hope to get it finished over the weekend if the kids let me!
 

Rich
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You have to think of it as a fixed wing because that is what it is.
If you pack out the TE edge of a free flight wing it will be because you have a nosing up problem, doing this alters the lift of the wing and reduces its lift.
The autogyro blade is the same, just 2 clarke Y lifting wings free wheeling. The disc is tipped back so as the forward speed of the model blows air up through the blades making them spin. If you can imagine a rigid fixed set of blades, the blade going into the wind has far more airflow going over it than the one going downwind (taking into consideration the aircraft is moving forwards). So the blade going into wind in this situation will always roll the model in the opposite direction because it is creating more lift due to the extra airflow over it?
To compensate for this the hub is made flexible or hinged. Making the blade going into wind flap upwards(reducing its lift), if you looked at this from the side the LE will move upwards just like adding packing to the TE of a wing. The blade going down wind will naturally straighten out, this evens out the lift on both sides.
 
Well that's the way I have always looked at it!

Rich

 
 
 

Edited By Richard Harris on 27/05/2011 12:21:14

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Fuselage pod is now repair and had several coats of paint (need to go over the white), I have also machined up a couple of machine guns out of alloy and epoxied these into to some holes drilled out. The gun shrouds are just litho plate.
 
 
 

 

The pod has a moulded in FG tube inside and simply slides up the main horizontal tube, it is held in place using the front steerable wheel.
I also made a new front wheel assembly a little longer so that it sits more like the real thing. The wheel bracket is made from the extruded box section of an old aluminium ladder. And the rod going up is off and old crashed Extra UC axle that was kept 'just in case'.

You can see 2 holes drilled in the side of the pod, these are the mounting points for the rocket tubes/missiles. I should get those done today hopefully. Also need to make a wind shield, time to look in the recycling bin!!
 
 
Rich
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Stefan,
Rotor span is around 60" maybe a shade under, the real thing is not the biggest of flying machines.
As a guess the weight will be around the 3.5-5lb mark, it is certainly heavier with all the filler and paint!!
 
 
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Danny,
I wouldn't say that, more like out of focus photos
 
Have completed the rocket tube 'thingys', these are made from bog rolls covered in solar film. The ends are made from litho plate, I just made a ply jig drilled with holes and gently pressed a wooden dowel in with its end rounded.
Missiles are made from wooden dowels with Litho plate fins
A photo of the front weapons trial fitted to one side (need to finish of the other!)

Can you guess what this is going to be?

Rich
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No one from behind stands a chance as I now have 'marker pen' flame throwersCovered in film with round dowel inserts at the front. Bad move covering them in film as they are covered in bubbles, unsure how to get these out?
These are mounted on alloy brackets and rods coming off mounts on the fin, its a bit on the 'porky side' so I am a bit concerned about this.

 
 
The motor has also been mounted, I am using a Waypoint W-E3014--20 turning a 10x 4 prop. This motor comes with a long shaft and helps to get the prop into the scale position.

The pilot is kind of 'stand off scale from 5 metres a way!', just carved from pink foam. The Ken Wallis head has been made for me by a friend, he got the plug carved while working over seas. I think he paid some young Indian lad 30p to do it!

Totally un RC related, I have a blackbirds nest in between my garage and workshop. Whilst out painting the foam pliot today one of the parents landed on the fence with a baby frog for their dinner. I only thought they ate grubs and worms etc!
 

So I took a few snaps
 

 
Rich
 
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Alan,
Thankyou but there is really not a lot to it when you break it down, carbon tube, glass fibre plate and a few bits and pieces.
 
I needed the help of my daughter as she is taking art in 6 form, she helped me try and mix the paint colours to make Ken a bit more 'life like'. Look at him close and he looks like he's on something! glad I never took art !!
Trying to make some hands and it didn't work out so 'action man' had it! I just hope my son doesn't realise he's gone missing
Took one more photo this evening with my transmitter to give a bit of perspective of its size.
 

Rich
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