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Member postings for Martin Harris

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

Thread: New Laser engines. What do you want?
19/11/2017 11:25:15

I'm not sure if it's me or the changes in the additives over the years but I find the smell of petrol quite unpleasant, these days, even to the point of feeling physically unsettled if I'm exposed to too much of the fumes. I certainly don't recall these effects back in the heady days when 5 star was still available and lead-free was just a nasty rumour from the other side of the pond...

18/11/2017 19:18:57

Aspen is something that I've meant to try - the only problem is that the nearest supplier is a lot further from me than the local petrol station! It does cost a lot more than I currently pay for 10% glow fuel but assuming the consumption is similar to ordinary petrol, a little should go a long way.

The point I was really trying to make is that glow engines are still a very practical power source and if we can indeed reduce oil content dramatically, a technology which should have a future in the hobby.

18/11/2017 13:02:42

There seems to be a great regard for petrol engines but to my mind, the "humble" glow has a lot going for it. It's no co-incidence that alcohol fuelled engines are at the "exotic" end of the full sized racing world - they produce far more power per cc of capacity than their petrol engined peers at the expense of using more fuel.

Getting back to "our" engines, the glow plug provides an automatic basic advance/retard function but if the occasional failed plug is unacceptable to some, there's always the option of running them on a spark ignition system. In fact, I suppose if you were a little paranoid here, some thought could be put into revisiting the provision of a second glow plug per cylinder as per the old Mercos etc?

Yes, petrol is cheaper and requires less lubricant, but it seems that Jon is making steady progress towards approving a dramatic lowering of oil content for Lasers (at the least) and in the quantities we use, cost is not a major factor. To me, the benefits of being able to store my models in the house outweigh the advantages of petrol. I do have one petrol powered (Z38) model - it takes up a lot of space in my workshop and even though I store it with the breather firmly blocked, there's always a faint whiff of petrol when I go in there. The cost of non-smelly Aspen would negate much of the benefit of using it and I assume it would still be as volatile as petrol?

Thread: 4.8 v or 6 v receiver packs ?
17/11/2017 19:28:46

I've just tried a quick test and (on my 2.4GHz radio system) the test servos (one digital, one analogue) stopped responding (at 4.11v and 3.79v supply respectively - measured in the receiver at 3.85v and 3.67v*) well before the receiver lost its link with the transmitter as I reduced the supply voltage to below 3.37v. Once the link was lost, increasing the supply voltage instantly restored the telemetry link (there's no easy way to tell if the uplink had been lost and failsafe had initiated as the servos had long since gone to sleep).

In practice, a failing cell in a pack should make itself known by erratic servo response (and in the case of telemetry equipped models, alarms) before loss of communication with the receiver.

I find it a little intriguing that losing one cell in a 4 cell pack means potential disaster while using a 2S LiFe is acceptable - I don't know what the typical failure mode of a LiFe cell is (if there is one!) but a pack dropping to 3.3v doesn't sound encouraging! That is the reason why my preferred power solution for larger/more valuable models is paralleled LiFe packs and switches.

Percy's is a good point but I suppose the answer is that the transmitter battery lives in a much kinder environment and is almost universally monitored for voltage level.

* The measured voltages at the supply and from the receiver telemetry were within 0.02v of each other with no servo loads at both the high and low points which illustrates the voltage drops in the wiring and receiver with the servos in operation.

Edited By Martin Harris on 17/11/2017 19:32:14

Thread: New Laser engines. What do you want?
17/11/2017 17:03:47

As I understand it, the change you've implemented relates to the supply chain - my main point is the careful evolution of the basic design of the product, skilled assembly and personal touch is the USP and I didn't mean to imply that the waiting list was a desirable feature - just a measure of the demand that is still being stimulated by the unique hand built traditional nature of the Morgan products in a niche market.

Should you be tempted to expand production and range by mass production, automation and/or sub-contracting as some seem to advocate, I feel that you would be in danger of becoming "just another" engine maker but I do realise this is just my personal view and meant as nothing more than an observation.

17/11/2017 15:55:43

To get back to Lasers, I'm no business guru but as a customer, the USP of Laser is the hand built nature and approachable support provided by John and Neil (although he's taken a back seat of late).

I remember a TV program presented by a well regarded captain of industry, Sir John Harvey-Jones where he took Morgan Cars to task for retaining their policy of hand building their cars in a traditional style and forecast their demise within a short timescale. While not my cup of tea (I can't stand that that flat, soft, time-wasting opium of the masses either!) time appears to have vindicated their refusal to modernise and upscale their production and to buy one, you still need to put your name on a waiting list.

 

Edited By Martin Harris on 17/11/2017 15:56:47

Thread: Super tiger needle valve
16/11/2017 23:22:43

As the contact info above seems to come from the American Hobbico site, perhaps this is an old number and the answerphone is lying forgotten in a dusty corner of Motors & Rotors since the sad loss of Mick Wilshere, who was the driving force behind Super Tigre engines in the UK - perhaps a call to their published number - 01923 270405 - would get a better response?

Edited By Martin Harris on 16/11/2017 23:23:33

Thread: A puzzle for engine guru's
16/11/2017 22:58:47

Slug of congealed oil partially blocking the exhaust outlet?

Thread: The way we were....
15/11/2017 22:40:06

Scrub the last question - I've spotted John now...I think I'm in that shot too...

15/11/2017 20:27:03

Thanks for posting these.  They certainly bring back memories!  I remember watching your first solo film at a club meeting far too many years ago.

Was the "new field" the one at Chenies? I think I spotted myself around the 8 minute mark but it's worrying as I don't remember the day at all!  Was the skinny blonde youngster John Greenfield - I know I had trouble recognising him when I got back into the hobby at the turn of the century...

Edited By Martin Harris on 15/11/2017 20:37:21

Thread: Drones fight back
15/11/2017 13:05:16

Scary concept...

Thread: Triple Connector
14/11/2017 20:04:39

If the model is of a reasonable size, a second servo is worth considering.

14/11/2017 19:40:52

Answers

  • Hopefully
  • An impending disaster
  • Crashed models which used one

Ok, I'm being cynical but I have found several of these loose when inspecting models for our members - on one occasion whilst diagnosing some rather odd flying characteristics for a rather traumatised owner who had just about managed to get his model on the ground in one piece.

Edited By Martin Harris on 14/11/2017 19:43:17

Thread: Quote of the Day
12/11/2017 23:28:27

With respect to your son, Chris, he's only had a few days experience on the road so he's on the very steep part of the learning curve which may bias his opinion.

It's like trying to compare apples with elephants but here's one way of looking at it:

Thousands of flights flying and instructing in gliders - 0 accidents during learning and subsequent flying as P1.

Multiple thousands of journeys driving cars and motorcycles - A handful of accidents but no write-offs - able to teach myself i.e. motorcycles, 3 wheeled cars (best way to transport models until I got a car licence) and minimal formal car test preparation. A fair proportion of accidents due to third parties.

Thousands of flights with RC models - many repairs and write-offs, many accidents during training phase with instructor assistance (pre-buddy boxing). The overwhelming majority of accidents due to my own pilot error.

On that basis, it's arguable that RC flying is far more difficult but there again, "pushing the envelope" is a lot more likely when the only casualty is fairly limited hurt to the wallet.

Thread: Bungy launcher ramp
12/11/2017 15:16:48

That must be some bungee to have left the model's batteries behind!

...and is that a box full of rolled up banknotes in the background?

Thread: Full size glider LiPo fire
12/11/2017 15:06:31

There was a tale from a world gliding championship in the 60's in Argentina where a glider was on a long aerotow retrieve over very inhospitable territory. The pilot was indulging in a cigarette and dropped it under the seat where it was unreachable. After a while, there was a whiff of burning and then some smoke. The glider wasn't fitted with radio and the chances of a successful landing were very small if he released from the tow so the pilot tried every way he could think of to reach under the seat and extinguish the burning, with the resulting gyrations severely disturbing the tug pilot who was close to dumping the tow...

Finally, he remembered that he had a bag of plums (possibly gleaned from the field where he'd landed earlier?) and rammed them under the seat, which rather fortunately did the job and extinguished the fire.

Somehow, I don't think that a bag of plums would help much in a LiPo fire!

Edited By Martin Harris on 12/11/2017 15:10:34

Thread: Super tiger needle valve
12/11/2017 14:46:09
Posted by Stephen Jones on 12/11/2017 11:10:18:

So is Super Tiger No more and this is a old Webb Site ?

Super Tiger.

Theie is a service supllier in the uk.

UNITED KINGDOM
Tigre Engines
Unit 11 Kingley Park Station Road
Kings Langley Herts WD4 8GW
United Kingdom
Telephone: +44 (1923) 269627
Fax: +44 (1923) 218840

Steve.

AKA Motors & Rotors...nothing to do with Webb's cheeky

Edited By Martin Harris on 12/11/2017 14:47:11

Thread: Glider Tow
11/11/2017 21:56:37

The only pitfall I can think of is whether the buggy would be heavy enough - equal and opposite reaction and all that...

Thread: Works fine on Spektrum but not on Futaba
08/11/2017 22:17:38

Good point - in case you aren't aware, to increase expo in the normal direction (softer around the centre) you need negative values as opposed to the positive ones you may be used to.

08/11/2017 17:56:05

Futaba throttle works in the opposite direction - change its direction, retrain the throttle and all should be well...

Edit: These answers are like buses - they arrive 3  4 at a time!

Edited By Martin Harris on 08/11/2017 17:58:02

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