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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: Broken switch T10J
19/01/2020 18:48:26

I've not looked inside one but past experience would suggest that Futaba switches are soldered on to PCBs. The DIY option would depend on your competence with a soldering iron - switches are likely to be commonly available types from various sources such as RS Components or Farnell but if in any doubt, contact Ripmax for recommendations - especially if it is under warranty.

Mike Ridley is a name often mentioned - I believe he was formerly a Ripmax/Futaba repair engineer.

Edited By Martin Harris on 19/01/2020 18:51:31

Thread: 7 Day challenge Nigel Hawes 30" Tucano...............
19/01/2020 01:02:44
Posted by kc on 18/01/2020 19:51:00:

\if you are just going to make a fake canopy you could use a chunk of white packaging foam ( if not too heavy) by sanding to shape with coarse new glasspaper and covering with brown paper ( etc) and dilute PVA. Overnight it becomes a smooth lightweight shape ready for paint. looks like balsa colour too.

Sanding foam is easier if you lift off between strokes [i.e.sand in one direction only] otherwise balls of material can form and rip chunks off.

Watch out for distortion as the PVA dries out - most 1/12 scale combat models used blue foam/brown paper and the skin gave all the strength required for high G turns - there were no spars used at all. I always coated top and bottom surfaces at the same time to avoid warping.

Edited By Martin Harris on 19/01/2020 01:08:21

Thread: FrSky Major Update for most TX and RX
18/01/2020 23:45:08

I can't really comment on FrSky but my own system has had a number of software upgrades, largely due to the maker taking on board feedback and suggestions from users. Since buying a dedicated transmitter in 2013 to replace my previous module based setup, it has had major upgrades in both functionality and performance. While I could still be operating happily on the original firmware which functioned faultlessly and offered wide ranging functions I would have missed out on so many great features and improvements.

7 years after buying the transmitter, I have what, in pre-upgradable equipment days, would represent a new transmitter with many enhanced and new features, half as many channels again and LUA functionality - all at no cost! I'm also fortunate that all my receivers, some dating back to 2009, still function perfectly with the system - something my manufacturer has taken care to ensure throughout the process.

While Pete's advice to hold back and let others take the pain of early adoption is very sound in general, the relatively small RC community along with many informed users means that problems are likely to be picked up quickly and communicated so upgrading is normally safe with only a small waiting time should you be wary of your manufacturer's software testing capabilities.

Thread: 7 Day challenge Nigel Hawes 30" Tucano...............
18/01/2020 19:32:55
Posted by martin collins 1 on 18/01/2020 19:23:58:

Anyone know where i can buy some blue or pink foam on a Sunday!

Might help if we knew where you are!

Thread: CAA registration take-up?
18/01/2020 10:55:15

Isn't the point of the organisations getting involved to distance "serious" modellers from the "buy a drone and fly it down the street" brigade? It would appear that the CAA have been sufficiently impressed by the attitudes and competencies of them and their individual members to grant several exemptions and concessions.

Why would the CAA allow the organisations to collect registrations on their behalf unless it was of some benefit to them? Working with, rather than against or despite the regulator must add to the relationship.

17/01/2020 10:23:48

Is this figure for operator registrations only or does it also include competence registrations?

Thread: Dereck Woodward Bigga Bit
17/01/2020 00:22:07

You haven't picked up a couple of stainless steel washers, perhaps?

Thread: Laser Engines - Technical questions
16/01/2020 16:54:09
Posted by Jon - Laser Engines on 16/01/2020 15:00:08:

Having slept since we spoke Martin i have zero recollection of our discussion! In any case, it looks like you might just about get away with it but i would suggest a tank change you can squeeze a little more capacity out of this **LINK** in more or less the same space.

Sorry - missed the link when I read your reply on my mobile at the field. Interesting thought - would 16 oz be sufficient? My original intention was to use 2 11 oz SLEC tanks which you seemed to endorse at the time - although I don't recall specifically discussing duration.

16/01/2020 16:39:26

After some further thought, the effect - if it works - would actually raise the effective fuel head while the bottom tank was emptying and then reduce it as the top tanks empty.

The carbs are at the level of the tank floor.

Edited By Martin Harris on 16/01/2020 16:55:24

16/01/2020 16:01:19

The problem with removing the floor is that the tank bay overlaps the wing fixing plate for the front wing pegs.

The logic is that you fill the top tanks which, once they Ooverflow, spill into the lower tank. All venting is through the vent from the bottom tank which would be arranged to provide the "Laser" forward facing vent. As the top tanks supply the carbs, fuel is drawn from the bottom tank as the fuel is pulled while the tank vents.

16/01/2020 13:24:54

Earlier in the thread there was considerable discussion of the chicken hopper fuel system. I took my plans for my Tempest to Jon while deciding on the purchase of a 200v a few years ago and he thought I'd get away with the fuel tanks which, due to structural considerations and the very short nose, are not practical to lower. Now that things are progressing again and reading informed comment on other installations from Jon, I'm reconsidering the wisdom of "getting away with it".

Installing a chicken hopper system on a twin seems horrendously complex and I'm wondering whether the system illustrated below would work so perhaps anyone seeing a problem with it could comment?

20200116_125630.jpg

My initial concern would be that maybe one of the red tanks would not fill properly - and am I right in assuming that the suction involved in pulling fuel up from the lower tank should lower the fuel head seen by the engines?

It seems a much simpler solution if it will work...I have some T pieces on order so that I can do some practical testing.

20200115_195440.jpg 20200115_195428.jpg

Thread: Synthetic instead of caster oil?
15/01/2020 22:18:05

Is it that bad? I believe Model Technics Laser fuel contains ML70 and so does my usual supplier's, Southern Modelcraft. Jon seems to have no problem continuing with Neil Tidey's endorsement of Model Technics fuel.

Thread: What size model?
15/01/2020 19:22:43
Posted by Michael Barclay on 11/01/2020 10:21:02:

I was wondering how others decide on the size of a model when designing or buying a kit. Is it a practical descision, or an aesthetic one? Perhaps like me you think that above a certain size a model looses a certain appeal? What does the panel think?

Mike.

Mike's OP wasn't really looking for recommendations if I read it correctly, but on what others feel are their criteria.

My view is totally the opposite I'm afraid, as I feel that models gain appeal the larger they are! As others have already stated, they fly more realistically, are generally better to fly and can be detailed more easily. While nowhere near LMA territory, my larger models tend to be in the 18 - 20lb class in anything from 1/6 to 1/3 scale depending on the subject although the largest span was a 4m Discus which was much lighter of course.

Limitations to me are the size of my field, transport and storage. In practical terms, anything larger than around 80" span will need to have a 2 piece wing.

Having said that, my winter hacks tend to be in the sub 60" category.

My current [rather long term] build was largely guided by these principles - I wanted to build a Tempest and chose a 76" version which has a one piece wing [quite a large chord to accommodate in the car] and will use a Laser 200v which represents an affordable high quality power plant.

 

Edited By Martin Harris on 15/01/2020 19:36:36

Thread: YouTube Video you like
14/01/2020 15:13:04

Don't be misled by the title picture of the Mossie's little brother - worthy aircraft though it is. This Mosquito restoration story may be one of the best hours you will ever spend in front of a PC...

Edited By Martin Harris on 14/01/2020 15:16:48

Thread: Laser Engines - Technical questions
14/01/2020 13:19:23

It's certainly a video to show to the electrofanatic ICphobics...

Dare I mention the practicality of on-board glows in such an installation?

Thread: No Auto Rotation
13/01/2020 10:18:30

It seems sensible to follow the designer's recommendation on how to shape the blades but I have had 2 different twin rotor fixed incidence gyros that flew with flat balsa blades - a DB one back in the 70s and Cyril Carr's Kestrel which I built from an RCM&E plan. I did find it interesting that the Kestrel's rotors would actually stop in fast flight with the tiny aerofoil sectioned rotor support/winglet obviously providing sufficient lift to support the model.

Autogyro

Experience with both mine and a clubmate's version was that the blades were prone to failure at the roots - on several occasions I landed with less blades than I took off with...

Thread: Which engine ?
12/01/2020 14:14:58
Posted by Martin Harris on 12/01/2020 13:57:32:
Posted by Jon - Laser Engines on 12/01/2020 12:23:27:
Posted by Martin Harris on 12/01/2020 10:31:25:
Posted by Jon - Laser Engines on 11/01/2020 23:36:40:
 

Certainly is an ASP - maybe a "budget" engine but it's soooo smooth...and sounds superb.

 

I have an ASP 160 twin as well and is is very smooth running. I have to confess though, the noise on the straight pipes is not to my taste at all. I had the same experience with an OS 300 super gemini but once i fitted a muffler to it then i was sold as it purred like a kitten so i suspect the ASP will be a similar story.

I made a siamesed silencer for mine from a stainless steel salt and pepper set found for the purpose at a car boot sale and using the open pipes for headers so except for some initial test bench running I've not had any experience of the bare pipe sound. At tickover it's barely audible and prop noise is the dominant sound at higher revs. It may be a little over restrictive as I found the engine very needle sensitive when running with exhaust pressure so I simply blanked off the silencer and run vented to atmosphere now.

 

...and at just past 3 minutes was the last occasion I ran pressure!

Edited By Martin Harris on 12/01/2020 14:19:09

12/01/2020 13:57:32
Posted by Jon - Laser Engines on 12/01/2020 12:23:27:
Posted by Martin Harris on 12/01/2020 10:31:25:
Posted by Jon - Laser Engines on 11/01/2020 23:36:40:

Certainly is an ASP - maybe a "budget" engine but it's soooo smooth...and sounds superb.

I have an ASP 160 twin as well and is is very smooth running. I have to confess though, the noise on the straight pipes is not to my taste at all. I had the same experience with an OS 300 super gemini but once i fitted a muffler to it then i was sold as it purred like a kitten so i suspect the ASP will be a similar story.

I made a siamesed silencer for mine from a stainless steel salt and pepper set found for the purpose at a car boot sale and using the open pipes for headers so except for some initial test bench running I've not had any experience of the bare pipe sound. At tickover it's barely audible and prop noise is the dominant sound at higher revs. It may be a little over restrictive as I found the engine very needle sensitive when running with exhaust pressure so I simply blanked off the silencer and run vented to atmosphere now.

12/01/2020 10:31:25
Posted by Jon - Laser Engines on 11/01/2020 23:36:40:
Posted by Martin Harris on 11/01/2020 22:54:24:

Certainly doesn't extrapolate to my 1/4 scale [just under 9 foot] one which weighs around 18 lbs and flies with more than scale performance on a 160 twin...

Is that an ASP 160? if sop they perform much like a decent 120 single so should be really nice. 1/4 scale is 105 inch right?

Certainly is an ASP - maybe a "budget" engine but it's soooo smooth...and sounds superb. Span is nominally 106" - exact measurement should be 105.75" so you're pretty close!

While I use the rudder a lot with this model, unusually for a model Cub it requires very little, if any, in normal turns. I put this down to it having proper Frise ailerons. There's little more rewarding than a slipping approach and one wheeled touchdown in a crosswind with this sort of model!

11/01/2020 22:54:24

Certainly doesn't extrapolate to my 1/4 scale [just under 9 foot] one which weighs around 18 lbs and flies with more than scale performance on a 160 twin...

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