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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: BMFA SUBS
19/11/2018 19:55:26

Were not all those benefits included at the old sub rate?

The question was what benefits is the 8% over the rate of inflation bringing.

I suppose this year there has been extra making our case with the authorities however if a significant part of the extra is due to rising insurance claims it does question the hobbies real level of safety and just when it doesn't need it.

Thread: ESC not working?
19/11/2018 16:26:53

The issue of LVC will depend on how many cells the brushed ESC thinks it connected too.

Some had auto 'cell detect' some had to be 'programmed'. How many cells in its original NiCd battery?

A fully charged 2s LiPo will be showing close to 8.4 volts.

If the ESC has auto detect it would likely assume 7 Nixx cells and set the Low Voltage Cutoff (LVC) to about 7 volts.

As Peter suggests this is just a bit 'early' for a 2s LiPo but quite safe.

If the ESC was a programmed type and was set for an original battery of 8 cells (9.6V) then the LVC will be too high for a 2 s LiPo cutting power at about 8V which would mean only about 30% of its capacity has been used.

The LVC for Nixx batteries was really more to maintain power to the radio before the battery ran flat so was not that critical unlike LiPo where maintaining a minimum voltage is vital to avoid permanently damaging its cells.

Thread: Upgrading electric motors
17/11/2018 23:01:02

This is my pusher. FlapVtail.jpg

However it is a bit more sophisticated than a V trainer. It has a relatively thin but reinforced wing with ailerons so it has positive roll control .

It is worth pointing out there is a difference between speed and power. A plane can be much more fun to fly if you have power that you only use when required even if it means you avoid exploring its absolute maximum speed! wink 2

17/11/2018 18:35:04

Not sure what a "V trainer" actually looks like but the Emax 2805 is a relatively low powered motor.

A simple substitute (it uses the same mounting holes) would be an Emax 2812, 1534 kV..

Same diameter as the 2605 but the armature is 12 mm long instead of 5 so nearly twice the power but it would have to drive a bigger 7x6 prop although this could be a problem if it is a pusher,

You would also need to change to a 30A ESC.

Your existing 1700mAh should be quite adequate provided it has a C rating of 25 or higher. You might have to move it a bit to counter the extra weight of the heavier motor.

If you can mount and swing a 7 inch prop don't be put off by the fact that is a pusher. Yes, a pusher prop is slightly less efficient,but on the positive side it does not "bathe" the whole fuselage in a high speed slip stream with the extra drag that creates.

I have a humble pusher with an Emax 2812, a 7x6 prop and a 1500 3s LiPo. Fast and fully aerobatic it even has flaps so it can fly very slowly too!

I would load a picture of it but this facility does not seem to be working at the moment! sad

Thread: Strengthen wing roots on HK Bixler and Walrus
17/11/2018 12:21:35

It would be interesting to have weighed your Bix as it was to compare when finished.

As with all reinforcing there is a danger that you simply discover the next weakest point. wink 2

It is also worth remembering that although extra weight only increases the flying speed by roughly the square root of the increase, both the power to fly and any impact forces increase in direct proportion.

In other words 10% heavier has to be both 10% more powerful and stronger to simply retain the same performance and crash resistance.

Thread: Civil Engineering advice needed
14/11/2018 12:01:32

Erfolg

It all depends on how much of the underlying soil has been disturbed or built up.

Tamping really only compacts an inch or two, the rest underneath will continue to sink until it reaches its 'natural' density.

To produce and maintain a truly flat patio you are likely to have to lay proper foundations, in other words, dig out to the undisturbed ground level and then build back up with a layer of material that does not sag, typically compacted hard core and then finish with thin layers of progressively finer materials.

Alternatively you can just re lay the sunk bits every few years. It will eventually stop sinking! wink 2

Thread: fokker dri wing incedence
08/11/2018 14:07:46

I am not sure stalling the bottom wing first is a sound idea.

I may be wrong but due to the wing stagger the bottom wing is behind the mean CofP of the 3 wings so when it stalls and looses lift the mean CofP of the still un stalled mid and upper wings will be further forward so creating a nose up pitch. This would not be desirable.

07/11/2018 21:35:00

No plans but this period drawing does suggest all the wings, and even the undercarriage wing, were all set at the same angle of incidence.

Due to the relatively close spaced wings the slot effect on the lower wings ensures the top one stalls well before the others resulting in a gentle but positive nose drop.

Note also the 'incidence' of the tail plane! My own much smaller Triplane with true scale wing sections confirmed it really needs to be like that.

Thread: Depron Eurofighter
07/11/2018 12:53:57

It might help if you can give some details of the construction of your Depron Eurofighter before you start to upgrade the performance.

Depron as a material has limited strength and stiffness so it could be that the original set up was chosen for a valid reasonwink 2

If we assume your Eurofighter is correctly set up and it is a Hobby King Propdrive 2830 1100kv then it is rated at 26A max so maybe more power is as simple as going to a 4s LiPo battery. With thhe same prop it would give nearly 50% more power.

If you want to play around increasing performance you would be well advised to buy a Watt meter. This will give you a real time reading of exactly how many Amps and Watts it is taking. More to the point it also means you can stop a test before you "fry" something!

A new 40A ESC will be required unless the existing one is rated for 4s.

With the same mAh capacity a 4s LiPo will weigh 1/3 more but that is about as much added weight as I would recommend.

Note you don't get "something for nothing" so the full power endurance will also be reduced but hopefully you won't need to use full power all the time.

Edited By Simon Chaddock on 07/11/2018 12:58:57

Thread: Spektrum transmitter for a beginner
07/11/2018 12:09:43

Be aware DSM2 is an out of date protocol that is no longer allowed to be sold new in the EU.

I understand DSM2 just checks for 2 free channels at switch on and then simply hops between them. DSMX on the other hand is a real time channel hopper that also checks the next channel is free before swapping.

DSM2 works fine in the "quiet" environment where I fly but at a busy "fly in" site it ran into loss of control trouble on 3 separate occasions. My planes that used DSMX versions of the same rx (my DX6i tx works both) had no problem.

Thread: Build versus flying time
04/11/2018 12:10:17

The build/flying ratio is surely a matter of individual preference.

On my more complex scale planes I doubt if their flight time will ever exceed their build time (I "build" in Depron) but to me the interest is designing, building and then seeing if it actually flies as intended.

To be fair the hours available for me to "build" are whole orders greater than the hours when flying is even possible.

Some planes don't get flown that much, other much more often if only to "keep my hand in" or rather fingers! wink 2

Thread: Problems I'm having
02/11/2018 01:01:26

nigel

Depth perception is a problem with simulators using a 2D screen as part of brain knows it is a flat screen so is unable to accurately process it as a 3D image..

An experienced RC flyer manages better simply because his brain has been 'taught' to respond to the image and ignore the effect of the 2D screen.

Out on the field the brain knows it is outdoors so is not so confused but accurate depth perception of a relatively small object at distance is still a serious issue.

Thread: EU Regulation of unmanned aircraft
30/10/2018 15:30:36

"If we were to get our activities curbed to open up airspace to allow BVLOS commercial flying then why make the concessions they already have to UK model flying?"

Surely there is a huge difference between changing a regulation to specifically permit low level commercial flying and just removing a concession that will then enable it. wink 2

Thread: EDF efficiency
29/10/2018 09:41:02

A ring around the tip of the fan blades is I believe called a 'shrouded' fan.

Whilst it will have no tip losses and apart from any structural issues what about the aerodynamic drag from the rings outer surface? It is a relatively large area that is travelling at blade tip speed.

It all comes down to which creates the biggest loss.

The fact that in full size turbo fan technology (the nearest thing to EDFs?) a shrouded fan has not been used suggests it is not a viable option.

Thread: log in
26/10/2018 09:20:13

It is a requirement of the site that you are logged in before you can write a reply.

Your problem is that for some reason your device or internet connection is causing this site to consider that you logged out when you last used it.

Thread: Need to Change Kit Specified Prop?
26/10/2018 09:09:01

It does depend on the way the battery is mounted but a 1800 mAh 3s LiPo will be a quite a bit lighter, about 3/4 the weight of a 1600 mAh 9.6V NiMh, so you may have to re-position it a bit further forward to maintain the correct CofG.

I can only reinforce Steve's suggestion to buy a Watt meter.

LiPo are very powerful batteries capable of delivering a huge current so are easily capable of burning out all the components (including themselves!) if unduly over loaded.

Thread: Ashbourne Scale Day
23/10/2018 17:02:04

That really is a truly remarkable video. It is really hard to tell it is not a full size Pup.

Well done to all concerned.

Thread: lipo battery heat
23/10/2018 16:39:22

Stan

Is your LiPo really getting that hot that it can damage its mounting?

In general if you discharge a LiPo over a flight at about half is rated C i.e at a 10C discharge for a 20C rated battery then it should not get too hot. The rate at which heat can be dissipated from a LiPo is limited, particularly from those of 3 or more cells as the 'middle' ones have no external surface. In addition each LiPo cell is encapsulated in a thick layer of plastic which is a pretty poor conductor of heat.wink 2

In practice you rely on the thermal mass of the battery to absorb the heat generated from discharge and aim that that the discharge will be complete before any of the cells have reached a critical temperature. A LiPo's life will be significantly shortened if it gets too hot.

The ESC on the other hand has very little thermal mass so it can over heat really quickly so adequate cooling is essential. To a slightly lesser degree the same condition applies to the motor although it does generate more heat.

Edited By Simon Chaddock on 23/10/2018 16:41:36

Thread: Ashbourne Scale Day
22/10/2018 22:34:29

And a big thanks from me for all those involved in organising a superb day - again!

Wind was a bit strong for my light weights but manged to fly 4 of the five I took and I even managed to crash two of them!

Thread: Did you start with ARTF and move to building from kits or vice versa?
22/10/2018 16:52:42

I started, like many of my era, building rubber power kits from Keil Kraft and Veron.

After a good few attempts, some more successful than others, I decided I could drawn my own plans so I could build planes of my own choice.

I have continued to do so ever since.

The last plane I built not of my own design was Peter Miller's Ballerina for the mass build challenge and even then I changed it a bit and used Depron. wink 2

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