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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: Crash resistant electric motor mounting suggestions please
21/03/2019 16:07:54

If you crash seriously enough to displace a strong motor mount what is going to happen to the rest of the air frame?

The original engine bearers also protected the engine itself which was a relatively expensive item but brushless motors are cheap (and don't thrash about) so it may be better to have a mount rigid enough for flight but that will crush/break thus absorbing some of the forces of a crash so minimising the damage to the rest of the air frame.

Just a thought.

Thread: C of G
19/03/2019 18:55:57

I wonder what was the weight of its original battery.

The wing has in effect quite a bit of sweep so I would expect the CofG to be a bit further back than might be expected.

The 2.4 m Replikit Minimoa described on RC Ggroups ended up with the CofG at 40% root cord as a "safe" figure!

I would only go that far back after some flight testing.

Edited By Simon Chaddock on 19/03/2019 18:56:36

Thread: Folding prop size
17/03/2019 17:41:20

Phil

With a Watt meter connected you could play around with the prop sizes until the motor to draws up to its 20 A limit on 2s and then change it for a folding one.

I would agree 2510 Kv is much too high. 1000kV would be better with something like a 9x6. Serious thrust and much better efficiency so a smaller battery for the same 'power on' time..wink 2

Thread: How many planes can you join together by their wing tips??
16/03/2019 23:32:01

A bit like the NASA Pathfinder solar powered planes. They had the benefit of very sophisticated control systems but it still eventually lost control and broke up. wink 2

Thread: Reduction Drive
16/03/2019 23:26:41

Cymaz

The use of the existing engine back plate bolts is a bit of a concern..

This diagram compares the thrust forces between direct and off set prop drives.

gearedprop

A situation is made even worse by the fact the bigger geared prop has the potential to generate several times the thrust of a direct drive prop.

It may be alright but.......

Thread: Gyro settings
14/03/2019 23:11:13

As Denis says you have to leave alone any setting that is required for straight and level flight so it will still fly with the gyro switched off and make absolutely sure the stability is working in the right direction to counter any motion upset. Negative stability tends to result in a crash in double quick time.

On the first flight I actually switched the gyro off until I was at a safe height and only then switched it on being instantly ready to switch if off again and safe in the knowledge I could still land the plane.

As the gyro rates were only set mid range nothing really happened except it flew very straight and level with no input from me! wink 2

After a few flights adjusting the gyro rates to give the level of stability I was happy with it can be left on all the time but beware getting lulled into a false sense of security and end up flying in conditions that really are beyond the plane's capability.

Edited By Simon Chaddock on 14/03/2019 23:26:52

Thread: Boeing 737 Max 8
14/03/2019 09:28:29

I think Mr T took credit for the announcement but he actually said was "the FAA after reviewing new evidence will ground all 737 -8 and -9 Max aircraft......" rather than "I have instructed the FAA......."

Thread: Charging Lipo batteries
13/03/2019 10:15:01

Duplicate 

Edited By Simon Chaddock on 13/03/2019 10:15:25

13/03/2019 10:15:00

Julian

First you must make sure that the round 12 connector from any source has the correct polarity (+ and -) for your LiPo charger before you connect anything. The charger should be marked to show what is required.

The drill charger is a bit small (0.5A) for your charger which requires 0.8A. As long as the = and- are the right way round on the 12 v connector it should work but it could take longer to charger the LiPo.

The train transformer has sufficient power but does it have more than one output? Is the main output reversible so the train can go either way?. As stated above the 12V connector must have the + and - the right way round.

Any fixed socket on the train transformer could be AC and would be of no use for your charger.

Remember a LiPo does not like to be left fully charged for long periods (weeks) and neither does it like to be run down below a certain cell voltage. For 'bench testing' (do not fit the prop!) you will only use a small amount of its capacity so it only needs a small charge or maybe none at all..

Thread: Inrunner or outrunner EDF ?
10/03/2019 13:52:58

EDFs were originally all in runners as they were the natural choice for smaller diameter and high rpm and this is still true for the smaller (<40 mm) EDFs where it gets more and more difficult to keep the out runner bell within the fan hub diameter.

As the can on an in runner is static it is relatively easy to add a tail cone to streamline the flow after the motor although not all seem to bother.

Out runners cool better than in runners indeed some in runners have to have cooling fins added to the outside of the can. This of course interferes with the airflow a bit.

Out runners are easier to manufacture so are quite a bit cheaper.

Thread: Antonov AN2
09/03/2019 17:00:55

Its tail plane has been carefully cut out from the fuselage, the slot enlarged and re-glued with the leading edge raised by 2 mm.

Modtail

This brought the tail plane inline with the required down trim of the elevator . The elevator linkage has now been adjusted so neutral trim is now inline with the tail plane. Should be about right but of course the weather is now far from suitable for test flights!

The undercarriage legs have been reprinted to give a couple of degrees of toe in as pushing the AN2 forward caused the U/C to tend to 'sink' whereas moving backwards caused the opposite.

The is almost no balsa in its construction just in part of the wing struts and tail plane braces so I set about printing these as well although I have no intention of fitting them unless a crash requires it! wink 2

The printed wing strut.

PrintStrut

It is 4 mm thick, hollow with internal bracing and weighs 4.5 g

There is a small (0.8 mm) hole at the end of each "leg".

RiggingHole

This allows the rigging can be directly attached to the strut rather than the complex inserted "tabs" I used originally. Being self colour they do not have to be painted either. wink 2

The tail plane braces require a modified fuselage former so would require rather more surgery to actually fit.

TailStrut

Of course the assembly is upside down in this picture but note the use of printer filament to create the attachment pins.

These bits will be kept in the 'spare parts' bag for future use - if required!

Thread: Reduction Drive
03/03/2019 16:23:59

cymaz

As I am sure you are aware any form of 'drive' has a rather hard time when driven by a single cylinder as each stoke gives it a torque reversal from compression to power

Of course the same happens with direct drive but 'power' props are fixed rigidly to the crank shaft and are designed to take it.

Important the belt (?) is set to exactly the right tension.or it will wear prematurely.

Thread: LBT
28/02/2019 18:04:43

Doc Marten

As others have suggested it is probably best to buy a new modern 2.4 Tx and receiver9s). It is by far the simplest route.

You can always do as i have done and keep the 35 meg for on some planes and 2.4 for others.

All you need to do is to decide which 'system' but don't to ask which is "best". You will get as many different suggestions as you get answers! Try to find a reason why one is preferable to you over any other.wink 2

Thread: Winters Here Who's Been Flying ?
27/02/2019 22:03:21

I too have flown practically every day, and on 2 separate occasions today!

The benign conditions meant I could fly some of my Depron oldies.

The still very original ducted prop Depron Hawker P1121 built in 2013.

24may16.jpg

And the 55 mm EDF Depron Fairey Delta Two of a similar age but it has had the benefit of a couple of major rebuilds!.

Acrylic blue

As a complete contrast two days ago the more recent but humble pusher Dppron/Printed 'Big Dragon'.

19may18.jpg

It gave me a stiff neck! but then its 3000 mAh 3s allowed me to fly it for 1 hour 5 minutes.smile p

Make hay while the sun shines - it won't last!

Thread: Steve Webb and World Model Kits
27/02/2019 09:51:56

I am fortunate that I live close enough to be able to go to Steve Webb's shop in Frodsham.

Well worth a visit if you get the chance but you need an iron will to keep the spending under control! wink 2

Thread: Electric setup advice
26/02/2019 23:45:39

Will

You will be surprised how hard it can be.

Compared to a motor cycle the amount of fuel that has to be delivered per stroke is minute and as a result more difficult to achieve accurately over the throttle range. wink 2

Thread: Canopy/Hatch magnets
21/02/2019 17:30:50

Remember the attraction force is proportion to the square of the distance so two magnets actually touching require a serious pull to separate hence the advantage of a thin covering to secure the magnet and reduce the pull a bit.

The other way is to use small but deep circular magnets which give a reasonable area for the glue to hold on to.

I like the audible "click" as the two magnets surfaces actually touch then I know the hatch is secure.

.

Thread: left or right thrust ?
19/02/2019 17:57:10

My own view is that counter rotating on most twins only makes a difference at the extremes of the low speed end of the flight envelope where the elimination of motor torque will likely delay the advent of wing drop and the 'spiral of death'.

Of course if one engine stops your must not be anywhere near the low speed end of the envelope anyway!

Another issue with the P38 was the problem of an engine failure at the point of take off. Although there was sufficient thrust to continue the take off 'on one' the problem was the single engine torque overcame the ailerons at normal take off speed. At one stage this caused more deaths than from combat..

The Lockheed test pilots found the solution - quickly throttle back the good engine a bit and wait for the speed build up.

One can imagine it took some training to do that!

Thread: Antonov AN2
16/02/2019 00:04:53

With the continued unseasonal weather the AN 2 has flown again with the elevator linkage adjusted and the battery moved forward 20 mm.

The object was to test the flaps. With full flap it made very slow progress into what was a very gentle breeze. Of course there was a huge apparent difference is speed of about 3:1 as it turned down wind! wink 2

The other factor duly tested was the break away undercarriage! An untidy landing with a noticeable cross wind gust caused the LH bracing to break cleanly away from its fuselage mountings.

UCbreak

No other damage so print another and install - simples!

This is the position of the elevator in normal 'trimmed' levle flight.

Downtrim

I don't want to move the battery any further forward as it will cause it to nose over too easily so the only alternative is to adjust the tail plane incidence a degree or two. It will require some careful 'surgery' to achieve.

I really mustn't grumble as it does fly just like it is supposed to - slowly!

Thread: Aldi Bench Drill
15/02/2019 18:32:33

You should really take it back for a refund or replacement as the drill is clearly not usable as supplied.

Anything else could leave you with a fairly heavy piece of scrap!

Of course you might get the two tapers to match using valve grinding paste as you do when grinding in a valve seat but it would be a horrendous "bodge" that would leave the chuck and drill as a unique matched pair!.sad

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