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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: Looping Hercules
21/07/2018 00:31:50

It seemed to fall over the top and a combination of a minimal fuel and payload plus lots of thrust may have limited the required G loading on the way up.

Thread: New Drone Laws from 30/5/2018
20/07/2018 12:44:09

The worry is what form any exemption is going to take and how universally it will be available. The press release simply stated that the CAA didn't see any reason why "an exemption" couldn't be issued but we are awaiting any news of what such an exemption will permit - and where.

My own club operates at the edge of the CTR of a major airport 3 miles from the extended centre line of the runway but in an area rarely overflown. We have an exemption, renewed annually, to allow 7 - 20kg models (and FPV) to operate to 400' AGL within a defined boundary - which we have been permitted to extend to 1000' on a couple of occasions. By my interpretation of existing legislation (and confirmed in a letter from the airport in 1982 when the club acquired its field) there is no legal control (other than that pertaining to endangerment and the requirement to maintain visual contact) to model flying at any height in controlled airspace.

While the 400' limit is sufficient for normal club flying, I doubt, for example, that we will be given an exemption for any models to operate above 400' which means the end for any meaningful thermal gliding at the site.

While I am obviously very interested in the outcome of negotiations, the fact that the BMFA haven't been able to issue an update is more likely to be that they see no point in speculating until there is an agreed outcome and I see nothing sinister in the lack of information. There will surely be a statement by the end of the month, even if no agreement has been reached and I am happy to await that.

Edited By Martin Harris on 20/07/2018 12:45:34

19/07/2018 12:46:31
Posted by Steve J on 19/07/2018 12:18:22:
Posted by Gordon Whitehead 1 on 18/07/2018 21:12:26:

Has anyone else out there got similar experience?

Altitude telemetry from my 30cc MX2. Mostly below 400ft, but it looks like I'm going to have to give up my flat spins and be careful with the stall turns .



A flight picked at random with a "typical club model" (Extreme Flight 58" Extra) flown through (I have little doubt - I picked totally at random so have no particular recollection) a range of appropriate manoeuvres - a few others checked since are broadly similar. I don't think the average club flyer should have too many worries if they aren't silly but I would recommend getting suitably equipped clubmates to demonstrate what different models look like at heights approaching the limits should no resolution be in place at the end of the month.


Edited By Martin Harris on 19/07/2018 12:55:22

19/07/2018 12:20:10

I always thought there was a presumption of innocence in English law and guilt had to be proved beyond reasonable doubt by the evidence presented by the prosecution. Any departure from this practice would surely be seized on by enterprising lawyers to launch an appeal against an unsafe conviction.

Thread: What actually is Storage Mode ?
19/07/2018 01:33:06
Posted by Allan Bennett on 18/07/2018 20:07:32:
30% reduces the risk of vent and flame even further (less energy in the battery) and, I believe, prolongs the life even further.

I'm not sure about that although I stand to be corrected. The last LiPos I bought came discharged to "transit level" with a note imploring me to restore them to storage charge levels as soon as I received them as leaving them for any length of time would damage them. This was supposedly to comply with postal regulations although I can see no obvious reference to this in the Parcel Force website guidance.

As I'm a LiPo Philistine, regularly discharging to 10% and charging them fully either immediately after use or just before the next session without obvious detriment to their useful life I'm not totally convinced - but that was the supplier's guidance...

Thread: Blackhorse Hurricane 46
18/07/2018 15:33:48

I haven't ever checked the scale outline on Chris's model but it could be an attempt by the Black Horse designer to limit the need for the normal massive lump of lead that scale Hurricanes often need to carry...

Thread: New Drone Laws from 30/5/2018
18/07/2018 14:51:33
Posted by Howard Winwood on 18/07/2018 13:52:31:

lets have some common sense here, IF there are aircraft flying over or near your club field then you have a responsibility to fly carefully/safely or not at all untill the hazard has passed. IF there are no aircraft anywhere near then what is the problem?

IF the authorities want to check your height, they would have to stand on virtually the same spot in order to triangulate the height.(short of regulations forcing models to carry telemetery equipment to monitor height and I doubt that will happen.)

IF there were ever to be an accident with a commercial or private aircraft, then it beggers the question, should that person have been flying his model anyway?

Stop the doom mongering and get a dose of common sense.

Stop blaming drone users (that is ALL of us if you bother to read the blurb).

Just carry on as normal.


Advocating ignoring the law because it doesn't suit you and you think you can get away with it...

Common sense?

I think not.

Edited By Martin Harris on 18/07/2018 14:53:08

18/07/2018 11:31:50
Posted by Howard Winwood on 18/07/2018 08:59:14:

how do you tell if you are flying above 400ft?, how do the authorities tell?

who is going to police it?

police do not have resources to tackle phone theft, burglaries or a lot of other crimes, policing drones (model aircraft) is not going to be a priority.

remember, the authorities have to PROVE you were flying above 400ft.

for most club flyers i doubt it will be a problem anyway.

The law will not be concerned with how you tell how high you are flying - it will simply be an offence not to comply. Yes, routine monitoring is unlikely to happen but as others have pointed out, in the dreadful event that your model caused an accident with another aircraft, your insurance could be invalidated and you could be prosecuted for causing death or injury by gross negligence or some similar offence. This is all above and beyond the simple prosecution for breaking the terms of the ANO.

Breaking the height limit accidentally at the top of a loop on the odd occasion is unlikely to be detected but should a complaint be raised, I'm sure it isn't beyond the wit of the authorities to measure by triangulation and/or electronic means during any investigation.

It would be in every modeller's interest to make every effort to comply with the legislation and implying (intentionally or not) that pilots need not be too bothered about the consequences is, in my opinion, very bad advice to be stating in public.

Thread: Holding Your Nose
17/07/2018 13:29:40
Posted by Tim Harris 1 on 17/07/2018 11:47:56:

What about a nose down test.? Might be useful? Could also be used to control grass length 😉

In the case of a pusher...

Thread: What setting for charging NiMH batteries
17/07/2018 01:25:56
Posted by John Lee on 16/07/2018 09:44:03:
Posted by Martin Harris on 15/07/2018 18:20:38:

However you charge, beware of any overheating - this is the real killer of NiMHs...anything more than warm to the touch will be damaging your cells.

What evidence do you have for that?

Panasonic, the maker of Enerloop, state that a temperature rise to 50 degrees (hot to touch) is normal & is not detrimental to the battery life of 2100 cycles, see the Q&A's on the link.

I didn't put that quite as I meant it. As I understand it, when a NiMH is fully charged, it converts the energy being put in to heat. Overcharging NiMH cells damages them and the fact that they are getting hot can be an indication of overcharge if the charging process hasn't terminated correctly.

It may well be the case that the different technology in Eneloop cells is more tolerant of overcharge or that heat generated during the charging process before the cell is full is allowable.

Thread: BAE Systems Tempest
17/07/2018 00:51:51
Posted by Tom Sharp 2 on 16/07/2018 20:37:01:

It says that the plane will be able to be operated remotely.

Therefore will it be subject to the Drone laws?

I suspect it will fly wherever and whenever it wants - I wouldn't want to try arguing the case with one!

Thread: Friday the 13th!
17/07/2018 00:45:27
Posted by Tom Sharp 2 on 16/07/2018 20:46:52:

My sister always used to laugh at my aversion to driving on Friday the 13th, until her son had a car crash on a Friday 13th.

Luckily not life threatening.

You can't argue with that logic.

It isn't worth it. crook

Thread: World Cup 2018
15/07/2018 19:36:26

Is that a variety of sour grape?

Thread: Holding Your Nose
15/07/2018 19:14:46

They're not difficult to tune - it's pretty simple but the discussion of this subject can make it seem trickier than it is. I'd venture to suggest that beginners can find anything other than pre-determined electric set-ups far more difficult to grasp - as evidenced by the many posts on the subject from those without a good grasp of electrical principles.

Thread: What setting for charging NiMH batteries
15/07/2018 18:20:38

Beware of false peaks if charging at 0.25C - make sure you've put back a reasonable amount bearing in mind the mount used. Charging at 0.5 -1C is supposed to give the most reliable results.

However you charge, beware of any overheating - this is the real killer of NiMHs...anything more than warm to the touch will be damaging your cells.

Thread: World Cup 2018
15/07/2018 17:53:52

Desperately sorry for Croatia. The better team in my opinion, put on the back foot by two very contentious decisions resulting in goals which forced them to expose themselves to counter attacks.

Very watchable match though and the record books won't give a true picture.

Thread: Holding Your Nose
15/07/2018 13:26:36

It could be argued that doing a nose up will guarantee sufficient air time to make those assessments!

Thread: The Mini WOT 4 thread
14/07/2018 18:16:28
Posted by Denis Watkins on 09/12/2017 16:55:24:

If you order 2mm silver steel, it is actually 2.1mm and far too tight to fit

I would change either my supplier or my micrometer...decent silver steel is ground to H8 tolerance and should be within microns of the correct size!

P.S. Nice one Percy...laugh

Edited By Martin Harris on 14/07/2018 18:19:55

Thread: Friday the 13th!
14/07/2018 17:35:56
Posted by Don Fry on 14/07/2018 15:15:30:

I had enough time to to think, "any answers to this problem" and brain cells took a vote. I shut the throttle. On the way down, I had time to ponder, turn the motor off?, and concluded it's going to hit slower at tickover.

Obvious mistake. You should have left the throttle wide open, stabilised to a prop hang, eased off throttle until it started to descend and torque rolled it back to catching height.


thumbs upcheekythumbs up

Thread: Do servos have a use by date?
14/07/2018 11:47:59

There are far more significant factors than age. I've had (decent quality) servos fail on initial power up and 30 year old ones that still function perfectly.

Life is affected by factors such as exposure to vibration, heat, load, shock damage, supply voltage, linkage problems etc.

Percy's advice to soak test unknown (and new) servos is very sound and will help identify intermittent problems and early life failures but as he infers, this test only guarantees that the servo worked properly on test - failure could be just around the corner but it comes down to acceptable risk assessment. I believe the important thing is to look carefully for any clues such as a slight glitch now and then, lower power than expected, any sign of mechanical wear (slop or roughness in gear trains, excessive output shaft play) and external damage.

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