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Everything posted by Martin Harris - Moderator
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Four stroke engine loosening prop
Martin Harris - Moderator replied to david james 1's topic in IC Engines
That’s unusual Paul. It’s often caused by too lean a mixture leading to pre-ignition. Lightweight wooden props can exacerbate the situation due to lack of flywheel effect, as can excessive compression and higher nitromethane percentages. -
Four stroke engine loosening prop
Martin Harris - Moderator replied to david james 1's topic in IC Engines
What type/sixe propeller are you using? What fuel? -
14 years ago, a very popular forum!
Martin Harris - Moderator replied to Phil Green's topic in Chit-chat
The thread title change makes it a bit clearer Phil - thanks. I recall being rather bemused by the change of name and the way Giantshark implemented their global replace does seem rather naive! -
14 years ago, a very popular forum!
Martin Harris - Moderator replied to Phil Green's topic in Chit-chat
A bit of nostalgia? Dates back to before the (rather odd!) change of name to Giantshark...certainly one of the nails in the coffin of many model shops with pretty good prices and good service (in my experience anyway). -
Signs of CoG too rearward ???
Martin Harris - Moderator replied to Witterings's topic in All Things Model Flying
In case anyone else finds themselves in the situation of wrestling with a wayward CofG, having been the victim of a few models presented to me to test fly after being assured the position was "as plan", the best advice I can give is to come off the throttle as much as practical for level flight, establish a neutral elevator position and try to avoid chasing the attitude/airspeed with it. Fly your circuit with as small control movements as possible - excessive banking will need elevator correction that may trigger overcorrection - and regulate your height and approach (as is correct practice) with the throttle. -
I’ve was given a Dart which has a “swollen” crankshaft where the intake hole is cross drilled - history unknown but maybe from crash damage? With the tiny power output of these engines, could yours have a similar problem allowing it to fire but not self sustain through excessive mechanical drag as the prop takes up any clearance and pulls the crankshaft forwards?
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It depends on the servo orientation. We had a club member who decided that Kyosho had somehow managed to make an error in their pre-installation on his new FW190, carefully removed and relocated the printed covering and reversed one hatch to allow the servo to be installed in mirror orientation to match the aileron servos (don’t ask!). It cost him two burnt out servos before he asked for advice… If that wasn’t bad enough, another member, experienced enough to know a lot better, did the same thing a few weeks later with his!
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Welcome to the forum, Emu. First step is to swap the extension lead connections to the servos. If the fault moves to the other flap then you have a faulty Y lead. If the problem is unchanged, suspect a faulty servo.
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Welcome to the forum. Joining a club is a great idea - you should get lots of help, advice and good company.
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Eneloop performance?
Martin Harris - Moderator replied to Robert Cracknell's topic in Gadgets and Electronics
Popular wisdom is that in order to reduce peak detection errors, you should charge at at least 0.5 C but it does seem that trickle charging at 0.1C may eventually cause damage. NiCd cells were so much easier to manage... -
Eneloop performance?
Martin Harris - Moderator replied to Robert Cracknell's topic in Gadgets and Electronics
My limited understanding is that they are physically/chemically different from “standard” NiMH cells, resulting in low self discharge but with a higher internal resistance resulting in lower performance at higher discharge rates. it’s a design characteristic rather than a quality issue. -
A new club - The UK Modeller’s Flying Club
Martin Harris - Moderator replied to Ron Gray's topic in Flying Sites and Clubs
I’m not sure that this is the case - and such a policy would spell disaster for our club. Our site is within controlled airspace but well away from the extended centreline of the local airport’s runway and has operated 7 - 25kg models with permission both directly from the CAA and via the BMFA for many years. (The club pre-dates the airport by 3 years and has operated from a number of sites within the local area/airspace before purchasing our present site over 40 years ago) -
It's a long time since I felt the need to use my tacho but it seems my recollection of needing a fluorescent lamp were a bit hazier than the light source! After digging my "Teamline" branded Min-Tach and a long search for an incandescent lamp (found one in the microwave!) it shows a consistent 3000 rpm with occasional drops to 2970 rpm (the same results as with a fluorescent tube) so I have to agree that modelling tachos can sense the minute filament cooling variations. At an approximate 1% variation in mains frequency, this seems outside Chris's specs but I don't know the minimum display increment or accuracy of the very cheap hobby equipment - maybe even some induced error through hand movement?
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Welcome to the forum Steve. Hopefully someone can help, although it's a rather old kit and hasn't been discussed for many years on this forum.
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I think it's more basic than that. An incandescent lamp running on AC cools so little during each cycle that it's undetectable with any (affordable) light sensing device whereas an old fashioned magnetic ballast flourescent fitting produces rapid on-off pulses of light. More modern electronic ballasts work at such a high frequency that even if if they were detectable, they would be outside the normal range of a tachometer designed for model engines.
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Help With Identifying Models
Martin Harris - Moderator replied to Acedmb's topic in Why Not Say Hello....
Welcome to the forum. To me, these look rather like promotional models that used to be issued to travel agents to adorn their shops. -
New members
Martin Harris - Moderator replied to Martin Harris - Moderator's topic in Why Not Say Hello....
An innocent explanation may well be that someone has googled for an obscure subject and happened upon this forum. The alarm bells in this case were 3 different posts on old threads arriving within an hour. -
There have been several posts within the last hour or so from new members with a common theme of being replies to long dormant threads with no form of introduction. This might be a sign that they are AI bot generated spam. This may well be coincidence but perhaps these new contributors might like to post a short introduction in order to validate themselves as genuine modellers so that we can publish their posts and welcome them to the forum.
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Ripmax Harmony Twin
Martin Harris - Moderator replied to Phil 9's topic in Sport, Aerobatic and 3D kits
Welcome to the forum. Feel free to introduce yourself! Do be aware that we have heard of scammers preying on forum members so beware of “My friend has one for sale” and similar responses, particularly from responders with low or non-existent post counts.