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Member postings for Geoff Sleath

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

Thread: Covering scissors
25/09/2017 15:09:23
Posted by Don Fry on 24/09/2017 20:00:52:

Might I suggest, that you keep a pair of good scissors to cut film and tex. And nothing else. And something cheap to cut brass and glass, wire. Sharpen the latter as needed.

Ask SWMBO if a dressmaker. Mine regards it as a divorce reason to look at her scissors.

My wife does needlework/embroidery and has a tiny pair of scissors sold to her on the basis they're too small for men to get their fingers in the loops! And they are, even for me who has small hands

I bought a cheap pair of scissors at a show years ago and was surprised that they cut covering film so well. They still do.

Geoff

Thread: The art of Customer service is (not yet) dead
24/09/2017 23:07:35

When I helped in the family shop up to 1961 I took great pride in being able to help customers. We sold and serviced radio and TV. as well as white goods and (believe it or not) shot guns and cartridges as registered gunsmiths. Every light bulb was tested, every radio, TV and electrical appliance was demonstrated and, if applicable, delivered and set up in the customer's home. Dad was interested in HiFi and we sold high quality amplifiers, mostly Quad and they were demonstrated in our sitting room. Unfortunately with the abolishment of Retail Price Maintenance (RPM) big stores were easily able to undercut us and as stuff got more reliable our USP, service, was less of a factor. I suspect the same has happened elsewhere in the retail trade

I was serving in the shop from about 11 upwards because we lived on the premises. That had disadvantages because we got people knocking on the backdoor if the shop was closed - even on Christmas day! By the time I was 21 I realised there was no future in retail and went to work with early computers. Dad struggled on for years too proud to admit defeat but, like model shops, small independent retail has all but disappeared.

Geoff

Thread: Forum members' new models: Let's see them.
24/09/2017 22:06:01
Posted by Peter Miller on 24/09/2017 18:56:04:

Easter Eagle Mk 3

Just finished this yesterday. One of my very old designs but actually build for a friend. Originals powered by 21 Turn Buggy motors and 7 cell nicads. Now uses the same power as my Kitehawk.

Span 55.Area over 600 sq .in. Wing loading 8 oz per sq. ft.

Based on Eagle and Vulture plan forms And yes, it does work well.

easter eagle mk3 2.jpg

easter eagle mk3.jpg

I'm surprised it isn't powered with a glow 4 stroke cheeky.

I really like the classy wing covering design and impressed by the low wing loading which, I assume, includes the battery etc.

Geoff

Thread: Understanding Watt Meters
24/09/2017 21:57:26

Mike, that leaflet doesn't agree with the motor specs. 911 watts on an 11.1 battery needs an 80 amp current draw to a first approximation. The motor is specified to have a maximum current of only 50 amps. So the maximum power with a 3S pack is 11 x 50 = 550 watts! It's better to use higher voltages (ie a 4S or 5S pack) once you're getting over a need for 500 watts plus. Running a prop that size is likely to burn out the motor or the esc if it isn't rated at a high enough current.

As I said earlier the quoted power of an electric motor shouldn't be taken as the power it will deliver as is the case with ic engines. It depends on using the right battery (ie number of cells or voltage) for the maximum allowed current. I much prefer to use a bigger motor than needed coupled with an esc with a good current overhead and then adjust prop size to provide the power you need whilst keeping an eye on the current draw.

Electric motors are much more versatile than engines but that means you need to 'tune' them for your needs.

Geoff

Thread: Programming Typhoon delta and Canards
24/09/2017 21:43:39
Posted by Bob Cotsford on 24/09/2017 18:51:55:

Geoff, do you have the rates and expo set up on the input page with the line using LS as source and named eg 'Canard' and the mixer line pointing to the processed output ((I4) Canard for example) rather than to the input source (ie 'Canard' or 'LS' )? Pointing the mixer line to LS or or using the line name Canard will bypass the input processing.

Edited By Bob Cotsford on 24/09/2017 18:55:33

That's it, Bob. Very quickly sorted. Thanks!

i like to use the Inputs to set throws rather than the Mixer because if using 2 separate servos for the ailerons for example (on a conventional model) it adjusts both servos at once. It was just annoying me as to why I'd done something silly.

RC Plane Flyer: Yes, that's the model I'm putting together. I thought that I'd just set the canards with the left hand slider and leave them alone for the first flights rather trying a mix. I'e put a little reflex on the elevons and was intending to set the canards just slightly up at the front to start with.

I'll have a look at the Norwich Flying Club site and read the PDF.

thanks

Geoff

Thread: Covering scissors
24/09/2017 18:02:44

We live half way between 2 small market towns (2.5 miles each way) and one has a Lidl and t'other an Aldi. The trouble is I can never remember which is where

Geoff

Thread: September 2017 Lipometer
24/09/2017 17:35:45

It's 20 years ago, Stevo and I used a 16C84 PIC with a keypad and LCD display. It reminds that I was once clever enough to do it Much, much cheaper to buy one.

Geoff

Thread: Programming Typhoon delta and Canards
24/09/2017 16:56:11

I'm programming my Depron Eurofighter which has elevons and a canard at the front which, I assume, acts as another elevator. I'm using a V8R4-II 4 channel receiver.

I've set up channels 1 and 2 on the elevon surfaces in the Mixer and they work fine. The canard is on channel 4 (channel 3 will be the esc) with the lefthand slider (LS) set up in the mixer which works OK.

The problem I have is on the Inputs section. I can set up the throws, dual rates and expo for ailerons and elevator OK but the canard won't respond to either weight or expo settings despite being identified by the name I gave it in the Mixer.

Moving the slider shows up on the graph but the canard itself, on the model, is unaffected even if I set the weight to zero.

It isn't a stopper. The model won't be affected but I'd like to understand why the transmitter behaves as it does.

Geoff

Thread: Understanding Watt Meters
24/09/2017 15:04:43

Mike, have a look at this set of prop tests.

Geoff

Thread: Aldi bargains
24/09/2017 15:00:18

We have a Boyes in Ripley, Derbys that stocks all sorts of useful stuff - a wide range of Humbrol enamel, UHU Por (and other UHU adhesives), Gorilla Glue and cutting mats. It's a small town department store I use a lot.

Geoff

Thread: September 2017 Lipometer
24/09/2017 14:56:15

Mal you're confusing different devices. As I understand it the LiPo meter is intended to be installed on a model to give an indication of how much energy has been consumed (a fuel gauge, if you like). A wattmeter is a device to use on the bench to measure current, voltage (and hence power) during a power train's setting up phase.

You can buy all the passive components, the Hall effect device and the 5v regulator from RS but the PLC (Programmable Logic Controller) will be specially programmed by the designer (it's a small self contained computer with its own architecture and special embedded software) and will only be available from him.

In any case, I don't think £24 is particularly expensive for the components, a printed circuit board and the PLC. I've been retired for over 20 years but I've paid over £100 just for a prototype PC in the past.

Now if you think having an on-board fuel gauge is useful then that's a different question. Once the initial test flights have been done I've got a pretty good idea how long I can fly and still leave sufficient battery capacity for a go round and not discharge my LiPo too much. I can't remember ever having to rely on the esc cutting power because of low battery voltage so I don't think a LiPo meter would be useful for me. I can see that it was an interesting project, however, just like the optical tacho I designed for myself years ago that cost about 3 times what I could have bought one for

Geoff

Thread: building bench
24/09/2017 13:31:19

We were supplied with safety glasses at work because we sometimes soldered on the bench. Since retiring I've replaced them a couple of times and wear them always in the workshop and for reading. They've got stronger as I've aged but even if they hadn't I wouldn't be without them just for the extra protection from possible flying debris ranging from bits of wood, broken scalpel blade or swarfe from my drill. Eyes are delicate and easily damaged!

I wear varifocals for driving and flying as well as for just going out. However the first set I had were very poor. My current pair from a different optician are very much better. I think they need to be properly ground to work well but are fine if they are. I was offered several grades and chose the best and most expensive. Even then, I wouldn't use them in the workshop and much prefer my single focus safety glasses often assisted by a head magnifier for very close work.

Geoff

Thread: Understanding Watt Meters
24/09/2017 13:17:11

I haven't run 40 size glow engines for a while but I seem to remember that the usual prop was a 10x6 so start with that. Flat out that should be turning at about 10k rpm. I'd try a 10x6. What is the weight of the model?

The voltage drop you're getting indicates that the 4S battery you're using is OK but not stellar ( 50 amps is dropping 2v so the battery (and esc) have a resistance of about 40 milliohms or 10 milliohms/cell which is OK considering the esc has some resistance too).

The 3S pack is dropping 2.5 roughly so the series resistance is 54 milliohms or 18 milliohms/cell which is quite high. So not in as good condition as the 4S I would say.

The resistance calculations are only approximations because they include the esc in the source resistance. A good LiPo cell has an effective series resistance (ESR) of less than 5 milliohms and I regard as scrap any LiPo that goes over 15 and 10 is marginal.

What do you mean by hot? My calibrated finger can just about bear touching 50 deg. Is it hotter than that? Bear in mind that prolonged running on the ground results in stuff getting hotter than it would in the air - particularly flat out. I flew my Ballerina a few days ago. That turns a 12x6 prop at around 9k rpm IIRC and has a 4S LiPo. The battery is just warm after an 8 minute aerobaticish flight.

Geoff

Thread: A fairly severe 'nose' job!
23/09/2017 23:16:17

I admire your dedication to Depron, Simon. I'm just completing a cartoon scale Eurofighter in Depron I bought as a kit at the Nationals swap meet. It's an interesting exercise and I'm just hoping it actually flies! However it's just confirmed how much I prefer balsa and plywood but each to his own, I guess. Perhaps I'll get to like it; you never know!

Do you buy UHU Por in gross boxes?

Geoff

Thread: Are we being ripped off
23/09/2017 22:38:38

Rolls-Royce rely on the selling the spares needed to keep their engines airworthy to make the profit that pays my pension Spares have always been relatively expensive. Try building a car yourself from spare parts - I shudder to think how expensive that might be. The cost is largely absorbed in transporting, stocking, packing and storing individual parts. Some rarely needed parts may never actually be sold - that cost has to be absorbed and paid for ultimately by the customer buying more commonly needed components.

I was brought up in an environment where things were repaired. My grandfather set up his watch and clock repair business in 1878 and my father, his youngest son, extended the business to accommodate his own interests in hifi, radio and eventually TV. We were in business both to sell and to repair and we did. Now, who repairs ordinary watches? I struggle to repair electrical and electronic kit even though it was once my trade though I sometimes succeed.

Now I repair models aeroplanes. I'm quite proud that I managed to get my Dynam Hurricane back in the air this year despite a very bent nose and a wing in 3 parts!

Geoff

Thread: Understanding Watt Meters
23/09/2017 22:19:09

The maximum current for the 3548/4 is 50 amps and that would give a maximum power of around 600 watts on a 3S. I would limit the current to (say) 40 amps and around 500 watts. To get more power you would need to run it on either 4 or 5 cells keeping to the same maximum current draw.

When choosing a motor, the main parameters to consider are the kv (rpm/volt) and the maximum current (bearing in mind that maximum is often for quite short times). The quoted power rating is a secondary characteristic really only of value for guidance.

The ECalc figures quoted by Frank (particularly the current) show that there's no way to achieve 900 watts on 3S without exceeding the maximum current rating. How heavy is the model? The usual rule of thumb is 100 watts/pound for aerobatic flight but IIRC correctly my Ballerina is set up at about 80 watts/pound and has more than enough power.

Geoff

23/09/2017 17:08:26
Posted by minty morton on 23/09/2017 16:51:18:
Hi Mike. Something is wrong there. I use the same size motor and get close to 900w with 3s. The battery voltage is low and this could be the answer. Was the pack fully charged at the start of the test?
Hope this starts to get an answer.
Minty

Though it seems odd, the power rating of the motor isn't an indication of how much power a system generates (or tries to). It's an indication of how hard you can drive it without damage. The main generation of power (or torque) is the voltage and the load (the prop size) imposed.

However, as everyone has said the battery voltage is low which indicates either one that's exhausted and needs to be recharged or a faulty battery with a high internal resistance. 1100 rpm/volt is quite high for a 12x8 prop, too. The main use of a watt meter is to set up a system with the right size prop to get the current/power into the region specified by the motor parameters (ie max current, mostly).

Geoff

Thread: Transmitters for DSMX indoor receiver/servo modules
22/09/2017 21:46:29

A club-mate has just bought an E-Flite Convergence VTOLfoamie and found it wouldn't bind to the Orange module he has in his Taranis and had to buy a new transmitter to use it. He got a DX6e which binds and flies it OK.

I'm no expert on Spektrum but it seems the new indoor models and (at least) the VTOL foamie have a different protocol from the old DSMX and new transmitters are needed. I guess eventually Orange etc will reverse engineer it and produce plug-in modules for JR style carriers like the Taranis etc.

I stand to be corrected but that's what appeared to be the case.

Geoff

Thread: A fairly severe 'nose' job!
22/09/2017 10:58:23

Oops. My excuse is that the 5th is a very important date burnt on my mind for over 50 years - Avice's birthday

Geoff

21/09/2017 16:33:45

The thing is, Simon, will we see it flying at Ashbourne on October 5th?

Geoff

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