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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: Electric Cars.
21/05/2018 17:08:46

Does any know the efficiency of an automotive inductive charging system.?

Yes transformers and the like use induction to transfer large quantities of electrical energy very efficiently but they don't do it through air. wink 2

Thread: Electricity Pylon Interference?
21/05/2018 16:59:31

paul

You say you are not worried about flying into electricity pylons but anything, particularly if it is a bit wet can act as jumping point for very high voltages.

In other words the very presence of your plane flying close to a HV wire could jeopardise the normal safety distance and you don't want to be anywhere near as well as you too also act as a potential conductor to ground.

Very unlikely but it will only happen to you once!

Thread: Fledgling
16/05/2018 23:51:26

o z 1

If your ED 1.46 is just 'gummed up' from solidified castor oil then soaking will free it eventually!

If on the other hand the engine actually 'seized' whilst running then soaking will have little effect and repairs are likely to require some replacement parts which may well have to be specially made. wink 2.

Thread: Dead LiFe battery...
16/05/2018 20:49:02

Were you actually charging in the plane?.

You can see why it is not recommended as any 'fault' condition is likely to damage the plane or at worst completely destroy it.. .

Thread: Calculating Washout
15/05/2018 19:26:46

Just to an another variable swept wings or even swept back leading edges can reduce the need for washout.

As Peter Miller says parallel chord wings don't really need any at all .

My Ballerina wing has none and has very benign stall characteristics.

My scale Fairey Delta 2 (it is a pure delta and with a very thin section) doesn't have any either and it does not really stall. The maximum angle of attack you can achieve is only limited by the thrust available. wink 2

Thread: Don Valley mfc Open days 2018
13/05/2018 20:36:59

Still a bit far off for accurate weather forecasts but at the moment the BBC weather says Sat 26th will be "breezy"! sad

Thread: ESC only working with throttle trim fully down
09/05/2018 16:22:11

In my experience (with a DX6i) it is common and with many ESC essential that the throttle trim is set to minimum.

I actually set up the ESC throttle range like this so it becomes part of the before connecting the battery check - "throttle fully closed" or it will just beep and not arm.

To my way of thinking setting "throttle cut" is irrelevant with electric - just fully close the throttle. wink 2

Thread: DH 91 Albatross
09/05/2018 14:23:45

The RH wing plan enlarged from the 3 view.

Wing plan 1

Like many airliners its wing is highly tapered, The root and tip ribs!

Root/Tip ribs

The lower wing skin. It incorporates a balsa spar flange.

Wing RH skin

The skin is 'cold formed' to more or less the rib underside profile and the 3D printed ribs glued on 'free hand' making full use of UHU POR's excellent contact adhesive properties.

Wing RH ribs

The retract unit is installed. The cut outs for the wheel and leg will only be made once the wing is complete

Next is the Depron spar shear web between the ribs, the Depron leading edge and the top balsa spar flange. Only at that stage will the wing be 'set it' up accurately to allow the front top skin to be glued on to create a torsionally rigid "D" box structure.

Well that's the plan. wink 2

Thread: Spring 2018 is here...been flying?
07/05/2018 16:53:07

Slowly working through my 'alternative' planes so it was the turn of my Depron Bachen Ba 349 Natter.

Complete rebuild 2

Despite its 'ridiculous' air frame it flies remarkably well on its 6x4 pusher.

Loops are easy but the roll is slow as with no ailerons is only has the elevons on the short span tail plane.

Now quite old for a plane built from 3 mm sheet Depron sheet. It was first flown in June 2011.wink 2

 

Edited By Simon Chaddock on 07/05/2018 17:10:31

Thread: Grain direction
04/05/2018 20:54:24

If the fuselage is taller than it is wide then 'top to bottom' grain is logical but it also depends on what else the bulkhead is intended to do.

Thread: DH 91 Albatross
04/05/2018 11:43:07

Only modest progress. The parts for all four nacelles and their spinners.

4 nacelles 1

As two of the motors have left hand threads the spinners have to be retained by the provided prop nuts. Not ideal but it works well enough.

The wing is by far the most complex bit as it has to hold 4 motors as well as the retracts along with quite a bit of wiring!

The Albatross used an RAF 34 wing section.

RAF34

Looks conventional enough so in the interests of scale it might as well be used. wink 2

Although the electric retracts are small but so is the wing section and to make matter worse they have to be mounted quite close to the wing leading edge. smile o

No room for a conventional mounting so they are mounted directly into the 3D printed wing ribs.

UC rib 3

UC rib 4

Of course the retracts will end up being permanently 'built in' but on the plus side it is about the lightest possible installation. wink 2

The 5 rib 'set', in about their correct relative positions, that will make up the wing centre section, although it will eventually be a 'one piece' wing bolted to the underside of the fuselage.

L&R retracts

Exactly how the wing is to be assembled I am still working on!

Thread: Query on use of old Futaba 35Mhz equipment with modern electrics
04/05/2018 01:02:28

Although I fly mostly by myself I use 35 Meg (old Tx, modern(ish) Rxs) on quite a number of my current models with absolutely no problem using brushless motors.

When I do visit a club open day there are so few using 35 Meg I still have no problem!

Brushed motors are far more likely to give problems. Even with motor mounted capacitors the brushes still spark and sparks create electromagnetic radiation over a wide range of frequencies. wink 2

Thread: How large scale electric can you go?
29/04/2018 00:13:26

A car battery is capable of delivering 400+ Amps but but you can't feel a thing touching the positive terminal.

A static charge can run to 10.000+ Volts. It may jolt but does not kill.

Touch a 10.000 V power line when standing on the ground and you will fry, literally.

The difference is?

Thread: No discernible engine brake!
27/04/2018 11:37:20

As a general rule with any ESC you should set the throttle trim to minimum. Some ESCs will not actually arm until you do!

You don't need the prop on to check the brake is working. If it is working just run the motor up to speed snap the throttle shut. The motor will stop very quickly indeed.

It doesn't matter which way round the prop is turning the brake works just the same.

Thread: Prop adaptors: How tight is just tight enough?
25/04/2018 21:36:42

Just to endorse the danger of the collet 'bottoming' before it has fully gripped the shaft. As long as it is properly gripping the shaft aluminium on steel actually 'binds' at a molecular level so the smoother the surfaces the better. Indeed a good collet is likely to be the very devil to get off again after it has be left on for any length of time.

However once a prop adaptor has been over strained the collet surfaces no longer make intimate contact with most of the shaft so are at risk of coming off.

Thread: DH 91 Albatross
25/04/2018 10:07:32

It is perhaps worth remembering that in the 1930s DH were virtually unique in the UK in being a profitable civil aircraft manufacturer so it is.perhaps to be expected that they stuck to the materials that they knew best although developing innovative techniques in its use.

The engine nacelles on the DH91 are virtually circular, and there are 4, so it seems logical to 3D print them.

First the racing drone motor. Rated at 100W on a 3s.2000kv 2204

Small and light (24.2 g) with L & RH thread prop nuts.

The printed engine nacelle with a scale cooling air exit.

nacelled 2

Although a single STL file it is printed in two parts using the 'submerged bed' method so it is divided across the middle of the motor bulkhead.

nacelle front nacelle rear

The two halves are simply glued together although the joint is also held by the motor bolts.

nacelle D1

Cooling air cut outs are included.

The bare nacelle weighs weighs 9.2 g

23/04/2018 21:48:42

Over a fairly relaxed timescale I intend to build one of these.

forbisherfront.jpg

7 were built in 1937/8 using a ply/balsa/ply sandwich technique later employed on the Mosquito.

2 were completed as mail planes. The last 5 were built as 22 seat airliners and were used by Imperial Airways as the 'Frobisher' class .

3 view small

The exceptional streamlining and smooth surface finish offered an unmatched combination of speed and range. It was powered by four Gipsy 12s, a V12 version of the air cooled in line Gipsy 6.

Only in civilian service for about 6 months before they were all pressed into military service as transports in 1939. 4 crashed (but without loss of life) and one was destroyed in a bombing raid. The last crash 1942 indicated structural deterioration so the remaining 2 were scrapped.

It used 2 blade props so good for scalewink 2 and the retractable undercarriage used a simple 90 degree geometry. In addition the ailerons are of fairly generous proportions.although the twin fins extend below the tail plane so they could be exposed to landing damage.

My intention is to build it using a Depron stressed skin structure with balsa reinforcement thus to a degree mimicking the full size construction.

The success of my Airbus A350 using small racing drone motors and 4 blade ducted props suggests it might be possible to use the same thing but driving slightly larger 6" 2 blade props. To scale this would give the Albatross a modest 66" (1676 mm) span.

still thinking.

Thread: How to triple strength of Depron without adding weight.
20/04/2018 19:45:10

That 5 mm underlay board is not the same as Depron. It is not nearly as rigid.

Used in conjunction with a suitable 'skin' material it works well and is admirably cheap.

The lower wing uses a 'skin' of cereal packet cardboard over underlay board ribs.Cereal wing 1

The all Depron version above is about 25% lighter for the same strength. Neither wing has any form of spar!

Thread: Recommendations for small pillar drill
17/04/2018 17:12:16

For hobby/DIY I would strongly recommend one like this.type of 'generic' pillar drill.

Nothing special but unless you do a lot of 'engineering' standard work it is a great deal cheaper the similar Clarkson.

I have drilled 1/2 " diam through 1/2" thick steel plate with mine but that really is about its limit. wink 2

Thread: Electric Cars.
13/04/2018 23:30:20

I have to agree with Erfolg. What is cost (financial and environmental) of making an electric car compared to IC.

The current electric car market price is rather heavily distorted.

To claim a real environment benefit the energy impact of both production and use has to calculated over its lifetime and then compared to similar for IC.

However I very much doubt it will happen unless there are some hidden secretes somewhere for journalists to find..

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