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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: BMFA 'B' Test Video Available
09/10/2019 18:24:58

Is there somewhere safer?

09/10/2019 18:08:57
Posted by Andy48 on 09/10/2019 17:46:32:
Posted by Martin Harris on 08/10/2019 15:29:11:
Posted by Andy48 on 08/10/2019 13:48:18:

A couple of interesting points.

1. Not connecting the battery of an electric model until nearly on the runway.

2. Taking the tx onto to runway whilst collecting a model as opposed to leaving it either with a helper or on the ground.

Both very sensible in my opinion, but both frowned upon in my club.

Time you got your club to move into the 21st Century...while normal practice at my club is to connect flight batteries on dedicated benches at the front of the pits, there's no reason why people can't some do) connect their batteries on the flight line. Perhaps raise a question at your next AGM supported by evidence such as the BMFA video. On the subject, I'd always recommend and encourage the use of throttle kill switches however and wherever the battery is connected.

I'd have more chance negotiating an acceptable Brexit deal!

Oh dear - do they still operate a pegboard for 2.4? I'd be very unhappy if I thought my club wouldn't listen to a well reasoned argument to update a procedure - especially where its endorsed by the BMFA!

Edited By Martin Harris on 09/10/2019 18:10:21

09/10/2019 16:40:08

I'd have been happy to pass it as part of a well flown test.

I'm not an aerobatics judge but I don't think it's reasonable to expect to perform a stall turn every time without initiating the yaw fractionally before the vertical stop without either a high level of skill (above B level) or a great deal of luck. While leaving some throttle in aids the rudder, to expect a simultaneous yaw at the top is asking a lot and if you watch the tail, the model rotates around it correctly.

Maybe not a 100% score in competition aerobatics - there was a noticeable yaw - but I'd say it demonstrated the elements of the manouevre and certainly wasn't a wingover.

I'm sure not everyone might agree with my assessment so, as a suggestion to the Scheme organisers, I would be just as interested to see examples of pass, marginal pass and fail standards for all the manouevres.  Perhaps if not aimed at candidates, such a video would be a useful aid for examiners in order to set level standards.

Edited By Martin Harris on 09/10/2019 16:47:01

08/10/2019 22:40:17
Posted by Tim Flyer on 08/10/2019 21:27:16:

It might sound pedantic , but I must say that I didn’t like the music on the latest B test video. For technical videos music is best only used if directly relevant to the subject. The music chosen on this film was also at a high level and I found it distracting.

I wonder if there are two versions? I've seen a similar comment of Youtube and couldn't understand the problem. While the version I've watched has music on the titles and end credits, there is a total lack of intrusion on the content.

Still, if this is the only criticism, then the Achievement Scheme can't have done too bad a job...

Edited By Martin Harris on 08/10/2019 22:42:00

08/10/2019 15:29:11
Posted by Andy48 on 08/10/2019 13:48:18:

A couple of interesting points.

1. Not connecting the battery of an electric model until nearly on the runway.

2. Taking the tx onto to runway whilst collecting a model as opposed to leaving it either with a helper or on the ground.

Both very sensible in my opinion, but both frowned upon in my club.

Time you got your club to move into the 21st Century...while normal practice at my club is to connect flight batteries on dedicated benches at the front of the pits, there's no reason why people can't some do) connect their batteries on the flight line. Perhaps raise a question at your next AGM supported by evidence such as the BMFA video. On the subject, I'd always recommend and encourage the use of throttle kill switches however and wherever the battery is connected.

On the somewhat premature reporting of the demise of IC, it's encouraging that some newer pilots at our club have moved up to IC after doing their initial training on electric models...perhaps the beginning of a trend? I hope so...

Thread: New to model flying but not new to RC
08/10/2019 15:18:51

Don't get too discouraged. The flying season starts on the 1st of January and ends on the 31st of December...there are often very good flying days (shorter, admittedly) in the cooler months.

Thread: Latest CAA Update
08/10/2019 00:50:42

Full size pilots don't retake their written tests every few years - keeping current with air law is simply something they are expected to do.

I imagine the argument would be along the lines that all association members receive regular updates from the BMFA via the newsletter and, if club members, will be able to discuss such matters with their peers - Joe Public would not be in that position. Alternatively, one of the twenty questions could be on how to stay abreast of developments and changes and only a one off CAA test would then be necessary to align with full size practice and cover any darker awareness agenda for prosecuting transgressors.

Thread: BMFA 'B' Test Video Available
07/10/2019 20:32:19

While I teach newcomers to remove the glow clip from behind the prop right from the start and encourage the practice whenever possible, unless you can correct me Tom, I don't believe that this practice is mandated or even advised in the BMFA handbook, A Flying Start or CAP 658. I would not automatically fail someone for holding the glow as in the video if there was awareness of the hazard - you could see the operator was aware of the proximity of the prop by his slightly exaggerated movements - although I would discuss the advisability and alternatives.

Edited By Martin Harris on 07/10/2019 20:32:59

Thread: Latest CAA Update
07/10/2019 18:36:52

I would imagine that it's well under 250g so therefore exempt from the new regulations.

Whoops - too slow!

Edited By Martin Harris on 07/10/2019 18:37:45

Thread: 80 Mick Reeves Hurricane
06/10/2019 20:45:07
Posted by bert baker on 06/10/2019 19:10:52:

this is the second Reeves plane of this size I have had recently and both have ended up with full right aileron trim just to maintain level flight ....

are they all like this or is it just me

Have you checked your building board!

Edited By Martin Harris on 06/10/2019 20:46:26

Thread: Incidence Meter/Gauge Measurement
06/10/2019 16:43:02

If they haven't got access to a 3D printer, I'd imagine any modeller could knock one of these up in a few minutes from some scrap plywood.

I've certainly used my incidence meter on a number of occasions - one that springs to mind is my 1/4 scale Cub which has functional wing struts and needs them adjusting initially to set the correct washout on the non-tortionally stiff wing construction.

Thread: Sharing models - receiver / transmitter setup?
06/10/2019 13:31:47

Easy enough to duplicate the programming - but you would need to rebind each time you swapped transmitters.

Thread: Ailerons extending to wingtip
04/10/2019 23:06:46

Looks more like an FW190...

Thread: Guess the fault
04/10/2019 16:10:00

I monitor my receiver batteries all the time I'm flying with real time alarms if they drop below a preset value - the best justification for telemetry IMHO.

We had an interesting (tragic for the model) scenario at the club a couple of weeks ago when a friend asked me to trim out his model. I asked him to confirm that the battery was charged and he replied that he'd charged it and put a battery checker on it which reported 99% charge.

I took off and flew a couple of trimming circuits then performed a nice large loop. As it came back into level flight the engine went quiet and I called dead stick. As I was positioning for the dead stick approach, I lost all control and the model performed a high speed and terminal dive into the ground.

On reconnecting the battery, the servos responded OK but within a few seconds lost power and stopped moving. During the inquest it emerged that he'd given the battery an overnight charge and checked it at 99% - the only problem was that he'd used a Futaba standard wall charger and checked the 5 cell NiMH on a 4 cell checker. Futaba receivers have a facility which closes the throttle on encountering a voltage below 3.8V (possibly adjustable on some later models?) which explained the dead stick but of course, there's not enough power to continue moving the servos when a 5 cell battery is discharged to this level.

Edited By Martin Harris on 04/10/2019 16:12:59

Thread: LiFe A123
04/10/2019 01:26:39
Posted by Bill Reed on 03/10/2019 15:29:05:

So I have just been into a E-cig shop which sells A123 18650 cells and chargers. The cells look quality by the way.

The dedicated charger they sell charges to 4.2v ,my LiPo charger set to A123 will charge to 3.65v.

So whats correct? will the 4.2v drop pretty soon after the charge? if not its a big difference.

I've done a little research and A123s can be charged to a maximum of 4.2V but A123 Systems state that they recommend a maximum of either 3.6 or 3.8V depending on charge strategy.

Thread: Laser Engines - Technical questions
01/10/2019 15:08:43
Posted by David Davis on 01/10/2019 10:18:28:

Given that Jonathan is probably away on a well-deserved holiday I thought I'd ask the assembled expertise of this forum to see whether they could identify two Laser engines which I own.

One is obviously earlier than the other. It has the Super Tigre carburetter, the rocker box is retained by a single screw and it has a forward facing glow plug. It is stamped 62 RMT on the left-hand engine lug.

Sounds very much like my own Laser 62 which dates back to the 80s/early 90s. Jon can't supply parts for these but the advice from Neil Tidey was to enjoy running it until something eventually breaks! The engines were/are stamped with the purchaser's initials so it was originally Mr R.M.Txxxxx's...

Edited By Martin Harris on 01/10/2019 15:10:27

Thread: Prop balance query
01/10/2019 14:45:54
Thread: Balsa skin on wing
01/10/2019 14:08:14

Most wings have single curvature (i.e. constant taper from root to tip) so there should be little problem skinning with a single sheet.

As an alternative to ply sheeting, Mick Reeves sells very thin fibreglass sheet (Pro-Skin) which works on most wings or control surfaces without having to resort to slitting. Here's a link to it (that you would probably struggle to find on one of the world's worst commercial websites with some of the world's most useful bits and bobs!) - look near the bottom of the page...

Thread: Prop balance query
01/10/2019 13:55:18
Posted by Tom Sharp 2 on 01/10/2019 00:36:11:

There are a lot of words and attitudes in the Biggles books that would be considered very inappropriate in todays climate.

Nothing offensive about the word "airscrew" as far as I'm aware unless you have a rather mucky mind!

30/09/2019 23:26:48

Interesting point. Like many of my generation - and other generations no doubt, I was brought up on Biggles books and Capt. W.E.Johns made a point of the word propeller being an incorrect term for an airscrew.

Out of interest, I acquired a book written as an introduction to aeronautics for engineers by a relative, Arthur Fage in the early years of the century. He was a Fellow of the Royal Society and spent his working life in aeronautical research at the National Physical Laboratory in Teddington where, possibly due to his roots as an apprentice in the Royal Naval Dockyard in Portsmouth, one of his specialisms was propeller theory. My copy is the 4th edition from 1917 and in it, he explains that the correct term for an airscrew that pushes is a propeller and the name for one that pulls is a tractor - however he went on to state that the current terminology for all airscrews was "propeller".

Intrigued by this, I did a little research and discovered that the name was changed to "airscrew" during World War I by the RFC or RAF (perhaps after the book was written/printed?) and remained so until World War II, when reports such as "airscrew lost" could be erroneously trans­mitted as "aircrew lost". The name was then officially changed back to "propeller" which remains the case as far as I'm aware.

Edited By Martin Harris on 30/09/2019 23:32:13

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