Martin Harris - Moderator

Lots of Laser site grabs on the Internet Wayback Machine…

I've seen a few hand launch incidents with high powered models. I certainly launch my EFExtra at part throttle after watching some others' attempts!

I agree with Peter and believe the rated voltage is Futaba's way of referring to nominal battery voltage rather than the actual operating voltage range (referred to as such).

Easiest way is to "report" your post but you're welcome to drop a PM to one of us.

Just ask a mod. We'll often prefer to leave a thread existing if any useful related information has been added in follow up posts and rename it - usually with SOLD added to the title.

I wouldn't go behind 30% for a first flight - quite likely to have contributed to your misfortune.

The lack of rudder compensation was compounded by rapid application of full throttle. I (almost) always advise gradual and progressive opening - with typical model power to weight ratios vastly exceeding full size, it's easy to get into the situation avoided by pilots of high powered piston engined fighters where giving full throttle too early would lead to loss of control. Not only do you have better control authority as airspeed increases, but it's much easier to feed in progressive correction - there's a tendency to overcontrol otherwise. If the wing is stalled, application of aileron makes the situation worse by increasing the effective angle of attack of the stalled wing over the span of the aileron. P.S. P Factor is only one of several influences that pull a model to the left during take off. For anyone unfamiliar with it, this is the best graphical explanation that I've come across ...as you can imagine, the side of the propeller disk with the upgoing blade produces less thrust due to its lower angle of attack and this is coupled with the change in airspeed as the propeller blade moves backwards and forwards relative to the airstream as it rotates, producing asymetric thrust. These effects are more pronounced on taildraggers on the ground run - a typical tricycle model won't experience them until it rotates but gyroscopic, torque and helical airflow induced effects will still try to turn it left.

That explains it! I think my memory of the 150/120 equivalence was a bit hazy too. I’ve looked at earlier versions of the Laser site and it was their 120, designed to be extremely compact, which was down on outright power - they recommended using a 150 rather than their 120 but always stated that the 150 was more powerful and lighter than other 120s. It’s unlikely that Jon would have misidentified the engine but in the absence of such advice, measuring the bore and stroke to calculate it is the foolproof way to confirm capacity in any engine.

It was just that it seems to be mounted on the sloping bottom face of the mounting in your picture.

I assume it hasn’t been mounted as per the photo - it would end up with a rather offset thrust line at the very least! As for power, I’ve never owned a 150 but I seem to recall that they were regarded as an OS 120FS equivalent. Perhaps later ones had a bit more poke?

The straight line technique is known as dolphining. In sinking air, the most efficient speed to fly relates to the air’s vertical speed so various mechanical and electronic means to determine the best speed to fly at any instant during straight flight for best speed or distance have been used over the years. When lift is detected, this increased speed is converted to height and done quickly enough, enables a push over at less than the 1g stalling speed to maximise time in good lift before reestablishing an appropriate angle of attack to continue flight - or circle if the lift is strong enough to justify it. Frise ailerons carry a drag penalty so aren’t the answer for maximum efficiency but can be very effective. My 1/4 scale Cub has them and unlike the majority of Cub models, needs virtually no rudder in normal turns.

Surely the radius of turn required relates to the size of the area of best lift in the thermal. Classically, there's a core of faster ascending air - I assume some sort of toroidal effect due to friction effects on the outside of the "bubble" of rising air and this seems to be borne out in practice but in the heights at which model gliders mostly fly, lift - at least useable lift for full size, tends to be very disorganised i.e. below five or six hundred feet or so. At model flight speeds, it may be the case that a very flat i.e. low rate turn is sufficient to stay in good lift whereas flying at 45 -50 knots low down requires much tighter turns to work lift - reasons why inexperienced full size glider pilots are actively discouraged from low level scratching as coupled with misleading visual speed effects low down in any wind, there's little margin for error. So basically, there's a sweet spot in any thermal lift where a particular bank angle gives the best trade off of lift against sink rate - but remaining in balanced flight minimises aerodynamic losses.

Particularly in low speed flight with high aspect wings, due to various factors involving differential wing speeds, slip and dihedral, there’s a requirement to hold off bank, particularly in tighter turns, to maintain a constant bank angle. Easier in full size as the yaw string gives confirmation that this results in a balanced turn while maintaining an appropriate amount of in-turn rudder but the aerodynamics are essentially the same.

Post deleted. Sorry, but some posts are not acceptable in this forum - you should all know the rules by now.

And there was me thinking it was a clever counter-engine torque balancing modification.

Is that the Fokker Zwei Ein Halbdekker?

All part of trimming a model. Many model flyers think that keeping the wings level and not having to hang on to the elevator is all that’s required to trim a model! If you feel you can improve handling with some differential then why wouldn’t you experiment? To my mind, CAR is a cop-out and discourages good piloting skills.

There is a facility to "ignore" specific posters (hover over their avatar to find the option) but of course, quoted texts and replies to OT postings will still be seen.

I was always told never to say you were having a last flight…

Could I once again remind everyone that this thread isn’t about continuing specific arguments from different threads.

Is any of this relevant to the thread? I don’t think identifying a gardener who hasn’t completed a job for you is at all helpful and could even be potentially libellous so I’ve redacted his name.

We’ve had some new members from casual “walk ins” but most come via enquiries from the BMFA clubfinder, one of the few remaining local model shops or Facebook. At this stage, we ask prospective members to come to the field at a likely busy time when someone (usually the membership sec.) will be there to introduce them and get some mutual understanding of whether they will enjoy and benefit from our facilities and some general advice. We adopted this policy after a few people applying for membership found that they weren’t getting what they expected from the hobby. I’m not sure why any clubs would discourage visitors - if we see someone watching from the gate or boundaries, we invariably invite them in. If nothing else, it means we have some control over their movements but we normally find they appreciate the gesture and often have some interesting chats.

I’ve been less than impressed (read horrified) by the poor quality and ridiculous price of balsa in some of the non-specialist hobby shops. I would recommend traditional sources - some of which select and mill their own wood. Sadly, balsa isn’t as cheap as it was a few years ago though.

Let's not, please! I think most forum members have realised that some members have strong views on this subject which are unlikely to be changed by further discussion on the forum.

Apparently, the difference is defined by the seed type - angiosperm for hardwoods (flowering and broad leafed) and gymnosperm (such as pine cones) for softwoods. These are essentially enclosed or external seeds. There are also normally differences in stem fibres which transport nutrients from the roots.