Martin Harris - Moderator
-
Posts
13,411 -
Joined
-
Days Won
25
Content Type
Profiles
Forums
Blogs
Gallery
Calendar
Downloads
Posts posted by Martin Harris - Moderator
-
-
While we're waiting I'll give you a little laugh at my expense - the situation wasn't too far away from BEB's symptoms now I come to think of it!I was setting up a new ASP180 a couple of years ago and had the engine starting and running nicely. I put the engine in the new model I'd built and decided to give it a bit more running time in the garden to check the installation properly.Would it start?Fuel, plenty and in the right places,Glow,Compression,Nothing altered since the bench runs.Much head scratching and checking later,.......I got a slight sniff of what might be wrong.....when I realised that the bottle of Southern Modelcraft's finest attached to my fuel pump.......was the one that I'd put 1/2 a gallon of red diesel in to do some smoke generating experiments!.....Doh!Mind you, my face wasn't quite as red as a clubmate's who attached his remote glow earthing lead to the firewall mounting bolt of a plastic engine mount...
-
My pet hate? Arriving at page after page of adverts at the back of a magazine. BB (that's Bertie, not our Bas) wasn't cutting edge humour but at least it gave a last bit of reading and the odd snigger instead of the sudden coming to an end that many magazines give you. RCM&E's final picture goes a little way to softening the blow but it is nicer to have a final article of some sort.
-
The better day of a weekend sounds good to me - we are primarily a Saturday club but many are more Sunday orientated...
-
Which way up is it BEB? If it's inverted the fuel can continue to build up in the inlet tract but usually a 4 stroke clears excessive fuel quickly unlike 2 strokes which can collect a lot of excess in the crankcase. There's not enough valve overlap to allow the piston to push much out of the carb on the compression stroke with the valve closed for most of it! Does the fuel spit out continuously while cranking? I'm assuming you do have normal compression on this engine and that the inlet valve hasn't jammed open?I suspect that excessive richness will delay ignition as the fuel/air mixture will be more difficult to ignite - it's usually over leaning that causes detonation and prop throwing.Try a start without the initial priming to discount the over richness theory. Check the plug immediately if it doesn't run - if it glows straight away without needing to burn off excess fuel it wasn't too rich! If it's inverted have you tried starting it with the model upside down?
Edited By Martin Harris on 23/08/2010 15:50:53
Edited By Martin Harris on 23/08/2010 15:52:10
-
David,I think you may be better off vaguely in front of, but also to the side of a model which still has the option of being left on the ground than standing close to where one will soon be whistling past your ear'ole on its approachYours appears to be a lone voice - perhaps we've all got it wrong over the years and looked at in isolation yours seems a good point but but there are multiple considerations such as, for example, operating at one end of a runway can reduce visibility of the upwind end - particularly if the airfield isn't a flat unobstructed site which could hazard unsuspecting persons out of direct sight of the operator. How many models have wandered off line in the later stages of a stretched approach as a consequence of ground feature induced turbulence and reduced control effectiveness as the speed is decaying in the hands of an inexperienced (and sometimes not so inexperienced) pilot? Not too much of a hazard unless you're standing close to where it's being aimed - i.e. the threshold!
Lee's point was about tolerance and flexibility which I thoroughly agree with. -
Well said, Lee.
-
That's right, AA - the crankshaft timing mark will line up as you stated but the dot will be at the bottom of the cam housing on every other stroke. I recall seeing a great deal of correspondence on another newsgroup where people were arguing over whether the dot should be at the top or bottom when in practice, it doesn't matter as the ignition isn't physically timed to either stroke as it would be on most petrol engines.
Edited By Martin Harris on 23/08/2010 13:34:21
-
From the Ripmax site:It has come to our attention that a very small batch of SP113 Finishing Resin - identified with a Batch Code of E059 - has been incorrectly packaged and will not cure as expected. This only affects SP113 purchased during May 2009 and in the large 500g pack (Ripmax Part No. S-SP1132).
Edited By Martin Harris on 23/08/2010 12:53:19
-
I don't like the sound of the prop nut coming off which suggests that the engine is trying to fire too soon. As a glow engine has "automatic" ignition timing there's no adjustment short of a change of glowplug so there is a distinct reason to suspect valve timing.I suppose a grossly over-rich mixture might be causing hydraulic locking but it's unlikely the starter would spin it over normally which seems to be the case.The 3 to 31/2 turn main needle setting is for initial running and quite normal - you should run these engines grossly rich at first - even to the point that the glow needs to be kept connected. Obviously, once run in, the setting will have been progressively leaned to the more typical settings quoted. You could try leaning it a bit but don't get too enthusiastic and get it running rich as soon as possible.The low end needle which will be far more significant to the starting throttle setting shouldn't have needed altering but can be checked by blowing through a piece of fuel tubing attached to the fuel inlet nipple while the throttle is just cracked open (trap a pin in the rotor opening) - a small airflow should result - close until it stops and open until a steady hiss is heard to set an initial position if it's been disturbed.I can't say I've ever had to resort to using a knife on the cam cover - a simple gentle rotary rocking motion to break the seal after removing the 2 bolts has always worked for me - just ensure the gasket has freed before any larger movement is made or the cover is withdrawn If you do check the timing as per AAB's suggestion, remember that it only lines up every other stroke due to the 2:1 gear ratio.
-
c o g
in In The Air
If I understand the post above correctly I'm not sure this is good advice. The swept forward trailing edge will move the mean chord inboard with the result that the correct C of G point will be further forward at the root. in percentage terms. -
It sounds a little like incorrect cam timing. Is the engine brand new or could someone have fiddled with it before you got it?OS have a terrific reputation but even the best can occasionally slip up. I helped a clubmate with a new (to him but never run) OS70 which I discovered had an incorrectly machined cam gear which caused the timing to slip after setting it correctly. Ripmax were amazed that it had escaped from OS like that but were extremely responsive in replacing it.
-
Posted by kiwi g on 08/08/2010 10:51:30:
HAhahaha . yip great idea but at the same time, hmmm Might be alittle dark here at the same time you guys are flying. and why not wait till your winter, yipp then itll be nice and warm and i will feel like flying.
Should be OK if David picks a local date/time. e.g. 14.00 local on the nth of sometember -
I think this is a case of doing what you're comfortable with. Those people who've learnt to take off from the side - or have done it to fit in with local procedures, are probably quite happy to do it that way and those who habitually stand behind the model are uncomfortable doing it differently.I prefer to stand to one side and find no difficulty in detecting a deviation from runway heading as, apparently, do the majority of pilots at my club. I'm comfortable correcting any deviation and find I much prefer the side view for judging the model's attitude and initial climb out - but if I'm flying a familiar scale model, I usually use a reduced throttle and deliberately extend the ground run while balancing the model on the main wheels if it's a taildragger. I also like to see a positive rotation on a tricycle model but that's just for my personal satisfaction in trying to reproduce a full size flight pattern.On balance, I've come to the conclusion that reducing the frequency of people going onto an active runway is preferable to any perceived advantage in making corrections from behind and I prefer to see people learning that way from the outset - I believe they will be better fliers for doing so. As at Stephen's club, there's no rule at our club against going on to the strip to take off after clearing it with existing fliers and I'd take issue with anyone trying to enforce their own opinion (like Stephen's "friend"). However, I will, and do, encourage the few who still prefer to walk out to stand behind their models to try taking off from the pilot's box, offering guidance and assistance should they wish to extend their capabilities. Those who've responded seem to be quite happy continuing to do so once they've gained confidence in the exercise.While I do appreciate Stephen's point about quickly resolving a problem I still think that it's less hazardous for someone to walk out to attend to it and quickly clear the runway than to be on the runway for an extended time for each take-off.Although I've never actually seen it happen, I'm sure that cases of pilots tripping or getting seriously distracted from their flying while trying to return to the pilot's box must have occurred and the consequences of an uncontrolled model while they're picking themselves and maybe their transmitters up could be rather serious. I have witnessed pilots taking an inordinate length of time clearing the runway, stopping to fly their models to a convenient position in the circuit (some of our boundaries are quite tight) before taking a few more steps towards "home". I've also had to hazard a deadstick model in order to avoid causing danger to 2 elderly gentlemen guiding each other back from a take-off who were seemingly unable to hear me or take action in response to my deadstick call.
Edited By Martin Harris on 21/08/2010 18:35:24
-
It's your Cyclon, Peter.
-
Great fun for your son. I thought the flight deck was completely out of bounds since 911 and locked doors.I flew with a lot of people who were scared of heights n my gliding days and without exception, they were surprised that they didn't find any sensation of insecurity and were able to enjoy the experience - look what you've been missing all these years!
-
I never realised that the rudder worked differently when you're standing behind the model! Is it due to stronger radio waves?
-
Sorry - didn't make myself clear, I was referring to my charger's algorithm...
-
Good point - I know it does "sense" the end of charge but whether it's a time based algorithm based on the point where it peaks at the constant voltage or something else, I have no idea! I'm currently (no pun intended but it might as well stay) charging my 75A/h leisure battery which has been steadily increasing its voltage over the past 20 hours or so (limited to 3A by the capability of my 5A switched mode power supply) so perhaps I'll gain some more info from monitoring this although I'll probably be asleep before it's complete!
-
It's been bothering me that the figure I (eventually) gave at an earlier part of the thread seems to be at odds with that posted by some trusted and proven knowledgable contributors and I must admit it was from memory and I hadn't checked before posting.However, on checking the manufacturer's sites to refresh my knowledge, I believe I may have been more or less correct. The figure I quoted (2.45V per cell) agrees with both the Hawker Cyclon lead/tin and Yuasa SLA information as far as I can tell. What I think has been recommended is the float charging voltage but our batteries are normally used in cyclic discharge mode which ties in nicely with the settings on my multi charger.Here's the relevent charge information for a 12V 1.2 A/h SLA battery from the Yuasa site:
Reference to the graph shows the battery voltage rising to the constant voltage of @ 14.7V - which divided by 6 equals 2.45V per cell. Based on this, I'm more than happy to continue using my relatively cheap and cheerful multi charger to recharge my SLA cells. I know Timbo has linked to the Giant Cod version before but I'd recommend something like this to any half serious RC modeller.Edited By Martin Harris on 20/08/2010 17:32:09
-
Well, there's nothing wrong with touching down near the threshold - and what most capable pilots will aim at, finishing with a roll out to depart the runway at an appropriate place. What's at issue is where you're standing and I still contend that it's more hazardous to be standing close to a model that's descending through the last few feet i.e. head height,and often coming in to ground induced turbulence, than a possible situation at shin height.
-
Don't get fixated by specific site layouts and circumstances. We're looking at the big picture and trying to minimise uneccessary hazards. Local rules exist to take specific differences from the ideal layout into account.
-
I use a heat gun. I doubt that a hair dryer would be hot enough.
-
Posted by Stephen Grigg on 20/08/2010 11:54:18:
I put the question of standing behind a model to one of my expert collegues today.Unterestingly he states, If you are going to maiden fly a new model it is essential to stand behind it because you have no idea what it is going to do and your peripheral behind the models allows you to react much quicker.Once the model is trimmed and set up correctly it is than safe to take off from the side.Are there therfore times like this when clubs allow there modellers to do this on a maiden flight?Sorry, but as someone who is regularly asked to maiden models for other club members, I have never felt the need to stand behind one. I have a left hand which controls the rudder AND the throttle! Quite frankly, I'd question the competence of someone incapable of using these 2 controls from any direction and angle to maiden a model for someone else. It's just as important to monitor the pitch control aspects which you then have a proper view of as well as a perspective view of the direction of the ground run which should be more than sufficient to assess its direction.Posted by Stephen Grigg on 20/08/2010 12:10:02:
We all these rules you other clubs have,where do you stand when you send a model off with a bungee!!!Usually at the side of the runway from close to the pilot's box. Like a hand launch, there's no ground run to consider.
-
Posted by Chris Bell on 20/08/2010 10:52:26:
Its not a qualification - its an achievement ...
ChrisFair comment - although it's seen as such at most clubs.
R-C.co.uk
in R/C Retailers / Distributors / Manufacturers
Posted