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Member postings for Simon Chaddock

Here is a list of all the postings Simon Chaddock has made in our forums. Click on a thread name to jump to the thread.

Thread: Warbird Flyers, highly tapered wings...
19/09/2019 12:19:05


Try building a scale modern scale airliner! The root and tip section of my Airbus A350..Root Tip

It is of course quite highly swept and fairly flexible which seems to "pacify" its characteristic somewhat although positively exploring the extreme parts of the flight envelope is not recommended. wink 2

I would suggest go ahead, build to scale and simply treat it with respect.

Edited By Simon Chaddock on 19/09/2019 12:20:35

Thread: Antonov AN124 Ruslan
19/09/2019 12:06:42

The RH inner wing being assembled on the preformed lower wing skin which also incorporates the lower balsa spar flange.


Depron shear webs are added between each rib. The double shear web indicates where the outer wing panel joining tube plugs in.

The extra ribs ahead of the spar indicate the nacelle pylon positions.

Next the upper leading edge and the top spar flange are added.

RHinner2 This creates a very strong and stiff D box so the wing can be lifted from the board and safely handled.

The bag contains the 40 smile o printed rib components required for the LH inner wing panel.

17/09/2019 14:10:11

Like my A350 the AN 124 will use a considerable number of printed parts probably rather more as it rather be bigger!

The wing will be in 3 pieces, a 1280 mm centre section with 'plug in' 700 mm outer panels.

I even managed to find a reasonable representation of the Tsagi 12% wing section.


The root wing chord is huge at 450 mm and far larger than my printer bed so many of the ribs will have to printed in pieces and glued together.

Ribs 1 to 3


The ribs use a "U" channel section with a material thickness of 0.2 mm.

There will be a single balsa/Depron/balsa spar. The 2 mm balsa spar flanges will be incorporated into the 2mm Depron skin.

The full set of 12 ribs for the RH inner panel out to the wing joint.


The wing join will use a 10 mm tapered glass fibre tube.

This will in effect be a test build. If it proves to be unsatisfactory I doubt I will proceed any further and even if I do it will most definitely not be a quick build. sad

Edited By Simon Chaddock on 17/09/2019 14:21:41

15/09/2019 15:10:51

My 'racing drone' powered EDF Airbus A350 flies rather better than I dared hope but could the principle be expanded into a 4 jet?

A couple of months ago an AN124 flew several times into Manchester, and a smokey old thing it is, but it does has many characteristics that might work in its favour.

AN 124

Compared to the size of its turbo fans it is a big plane with a larger wing area than say a 747.

With a high wing layout it can belly land on the fuselage rather than the engine nacelles as does the A350. smile o

Its huge complex cross section fuselage is a negative both to build and for surface area drag but as a slow flying light weight the penalty is less severe than it might be.

Using the same Drone motors on 4s and 4 blade 5x3 'fans' it comes out with a 2.6 m span. Rather big considering it will be made largely from 2 mm Depron to stand much chance of being light enough to fly on the limited thrust available.wink 2

My first "experiment" was to examine the possibility of printing the complete nacelle and pylon. The A350 was also printed but used a planked Depron outer skin.

It would look something like this.



Like the A350 it is in 2 parts, the pylon and motor mount and the nacelle.


A bit disappointing as the body of the nacelle is rather delicate and it weighs 44.5 g which is 10 g more than the motor and prop. It also takes over 4 hours to print both parts. sad

Although not a project killer as I can always revert to the more complex multi part but lighter A350 type of nacelle construction.

The next "make or break" decision point is the wing or rather the inner section that carries the nacelles. It will be all to easy to end up with a total weight that would make the 10 g "excess" of each printed nacelle pale into insignificance! wink 2

Edited By Simon Chaddock on 15/09/2019 15:12:54

Thread: Aileron Thickness
14/09/2019 00:44:42

There is no one rule fits all in aerodynamics so the design of an aileron depends to a large degree on what you are trying to achieve.

In a glider drag is more important than control response whereas in an aerobatic plane the requirements tend to be the opposite.

Then throw in the degree of lamina flow and the effects of Reynolds number and the "best" design of any control surface is likely to come down to come down to what best suits your preference.

Personally I go for knife edged and fully sealed using a top tape hinge but then I am an ex full size glider pilot. wink 2.

Thread: What replacement for brushed
12/09/2019 20:45:51


Its not the voltage that is the issue but the amps. If you are drawing 250 W from a 2s LiPo then that's 33 A which is pretty close to the Jeti's limit of 35.

As you suggest an in runner will likely be easier to fit as they use nose mounted bolts like the brushed motor but I suspect you will have to go to a 4s LiPo to get the Watts.

This in runner from Hobbyking should fit in the space and on a 4s is adequately powerful at 300 W with a 7x4.

The range of out runners is much larger (and are usually cheaper) so one could be found that would match the power of the 500 brushed motor on your existing 2s but as they are usually rear mounted are more difficult to fit in an existing fuselage.

12/09/2019 17:12:57

First I would have to say that a prop breaking twice in flight suggests something is seriously wrong with your motor prop combination. It really should never happen.

The Graupner Speed 500 BB is rated at 17 amps continuous. If you are within its specification then on a 2s (8.4 V) LiPo the motor is using about 150W.. It is hard to imagine a prop braking at this power level so your prop may be significantly over loading the motor. You will need a Watt meter to measure the amps actually being used.

A brushless motor requires a matching brushless ESC.

This leads to the next problem. A 150W brushless motor is tiny, both in size and weight, compared to the Speed 500 so it is likely the plane is likely will have to be re-balanced (battery moved forward?) to maintain the correct centre of gravity.

The chances of a direct bolt hole replacement are very slim.

I am not sure what a 'Graupner Match' actually looks like but it appears the conversion is going to take a bit of work to achieve but the end product will be lighter and have a longer power on duration as a result.

Thread: Ashbourne 2019
12/09/2019 11:48:11


I have already confirmed attendance to your post on the RCMF web site so gods (and wind) willing I will be there. .

Thread: Motor pulsing
11/09/2019 19:38:12

J D 8

Have you tried removing the prop to see if it still does it with the motor unloaded?

"Substitution" (one item at a time) is the most powerful way of diagnosing any fault.

I keep a spare working motor, ESC and battery driven by a servo tester to cover just this sort of situation.

The spare items do not even have to be of identical specification as in most case all you are doing is checking that it works rather than checking it delivers the same power. wink 2

Thread: Design & Build Dornier Do 24
08/09/2019 21:51:33

My electric Cessna O2 (Vietnam special ops,52" span) worked extremely well and the rear prop was no problem on a hand launch,


My fore finger and thumb could only just span the fuselage at the strut joint so were reasonably clear of the rear prop during the launch action.

I actually made it so the front prop could be switched off in flight to reduce the risk of prop damage in the belly landing.

The all black stood out really well at altitude.

Thread: Charge amps query
06/09/2019 21:44:32

fly boy3

1/10 the capacity of 7ah is a charge of 0.7 amps.

The charger will indeed reduce the charge rate as the voltage nears the batteries maximum of 2.35 V per cell or 14.1 for a 12V battery.

If the battery is in poor condition it will arrive at 14 v and so virtually stop charging well before it is actually at full capacity.

You can force almost any number of amps in by using a higher voltage but it will wreck the battery if you do which is why the 1/10 charge rate is recommended.

Edited By Simon Chaddock on 06/09/2019 21:45:06

Thread: Latest CAA Update
04/09/2019 00:11:21

I think this video says it all

Conventional model plane flying will be changed forever and become significantly more expensive.

It could be argued that the restrictions to RC model planes is simply 'collateral damage' from the desire to control the use of multi copters.

Thread: Lidl 8 foamie glider - Great for RC conversion - my full video here
25/08/2019 14:46:01


Of course not knowing what the original intention was but at the speed it flies at it does look more like a 'power' plane than an electric glider. wink 2

Thread: What is the minimum slope for a slope soarer?...
17/08/2019 20:54:40


You need enough slope for a sufficient 'volume' of air to be deflected upwards to give you have enough space to manoeuvre the plane and stay within the rising air area.

A volume deflected by a small slope means you will have to stay close to the slope and as suggested use a small plane.

It is of course a requirement that the slope is facing into the prevailing wind!

Beach sand dunes do have the advantage that the wind tends to blow 'on shore' more often than not.

'Flat lands' are good for thermals so get good at finding them with your powered glider. wink 2

Thread: Single servo ailerons
16/08/2019 12:03:15

I bet the OP is beginning to wish he had never asked. wink 2

13/08/2019 13:55:39

RC Plane Flyer

Definitely more up than down!

A down going aileron for the same deflection creates more drag than an up going one so although the plane banks it tends to yaw outwards away from the turn or in other words a good start for a spin if you are flying too slowly!

With modern light weight but powerful servos it is much simpler to use a servo for each aileron and then use the transmitter functions to control the aileron travel, end stops and differential action. Most Tx will have a differential function already available.

Thread: CHEAP small glider at Lidls!
08/08/2019 19:03:57

I just had to do one as well!

Although powered I decided to keep mine as light as possible (no surprise there!) and concentrate on aerodynamic improvements so it might thermal soar.

First issue is the trailing edge, or rather the lack of it!

Section 1

The cut off TE of the tail plane. The wing is even worse!

My solution is to create Depron 'extensions' that thin down to a fine edge.

The tail plane extension becomes the elevator. Simple top tape hinge

Elevator 1 The outer wing panel extensions become the ailerons, the inner portions are fixed.

Tiny 3.7 g aileron servos completely buried in the wing.


The similar elevator servo is buried in the fuselage just behind the cockpit with external pull/pull nylon line.


No rudder it is flown 'bank and yank'.

A small 18 mm diam brushless is 'buried' in the nose and turns a 5x3 folding prop.


It weighs 226 g (no registration?) with a 950 mAh 2s and needs no reinforcing of any sort.

The extensions add about 14% to the wing area so it flies pretty slowly yet its glide performance is remarkable.

It does indeed thermal well but being so small it is all to easy to loose sight of it at any altitude! wink 2

Thread: Hospitalised, my own fault - but ?
08/08/2019 18:12:20

Sorry to read of your accident.

A little tip for hand launch aficionados - glue 60 grit wet and dry sand paper on the faces of the grips!

Works a treat and is rather essential for Depron lightweights as you cant grip it that hard in the first place. wink 2

The grips on the rather portly fuselage of my V-1 and its EDF is high up above the fuselage.

Finger grips

Index finger in the hole, thumb and little finger (just reaches!) on the 'wet and dry' patches.

Thread: Registration of flying sites with NATS/ATC
04/08/2019 17:04:57

And if all sites have to be registered I doubt it will be free!

Simply banning hobby model flying is not politically easy but minmising the impact by making it 'expensive' on the grounds of safety is!

Thread: Don Valley MFC Open Weekend August 3-4th.
03/08/2019 21:45:49

I would like to thank all the members of DVMFC who contributed to a fantastic days flying today, hot and sunny and a just a gentle breeze so no problem for my Depron light weights.

Took 10 flew 9 (many more than once) and crashed one. Happy bunny!

Thanks again and for that very nice burger!.

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