Here is a list of all the postings Malcolm Frary has made in our forums. Click on a thread name to jump to the thread.
With NiMH, you note how much of the boat rides out of the water on a full charge at full throttle. When less of the boat rides out, its time to come in.
Doing it that way with LiPo is a bit fraught. There is very little between "yes I can go flat out" and "no, I ain't going nowhere". An alarm helps, but alarms are generally just for tone particular type of battery.
|Thread: outlet pipe?|
The real thing might have had its outlet below water, but you probably want to let your viewing public know that you have working cooling.
|Thread: Varnish transfers?|
In my railway model days some 40+ years ago, there was a type of decal that involved alcohol. Stretching memory, "Methfix". Checking memory with the help of google, they still exist, but it appears that today they come with instructions, which would have been nice back then.
Waterslide transfers consist of a layer of strongish paint or similar on a layer of water soluble glue on a paper backing. Applying requires that the glue be wetted and the transfer slid off onto its destination. Since the glue remains soluble, protection is needed, usually some variety of varnish to match the paint already there.
|Thread: Bend in a control rod ????|
A late thought - whatever the route of the rod, the same rules of geometry apply. Both arms need to be at right angles to the line joining the arm pivot points when the rudder is central to keep the response equal both ways. The shape of the (rigid) rod makes no difference.
Things might be different if using a snake. I haven't, so I would be guessing.
|Thread: Bristol Channel Pilot Cutter|
Reducing the size of a sail model usually results in severely restricting sailing opportunities (wind forces scale the wrong way) and/or reducing performance expectations.
Both can be got back to an extent by fitting a weighted keel under the hull. See the square rigger article in his months MBM.
Done properly, they are superb sailing boats, but they are not really beginner boats. A simpler yacht will give more painless experience on the learning curve.
A past member of my club had one. His habit of an evening was to take it for a walk the half mile length of the lake, buy a cup of brew at the kiosk down there, and let it walk him back. He only considered it a good session if he had water inside the deck boat. If I remember right, he had fitted an over-size rudder to give a bit more authority when tacking.
|Thread: Bend in a control rod ????|
I usually just go for straight, but arrange things so that a sideways step is needed at the servo end. I use an electrical wiring connector "choc bloc" to do this. The spacing between the two segments is about right, and the screw fixings allow me to sort any tracking adjustments needed.
If the long shaft won't fit, shortening is feasible and, with care, fairly easy. Lengthening is the difficult part.
What 400 motor? They come in various voltage ratings which usually appear on the label. A 6 volt max motor will run very fast on a 7 cell battery, but not for long. An 8.4 volt one, on the other hand, will run reliably for a long long time.
|Thread: Model No2 for New RC Modeller|
The aerial needs to be both above the waterline and not hiding behind anything that either absorbs or deflects radio signals. Metal and wet wood are very good at deflecting signals and or absorbing them. With a 40 or 27 MHz aerial, it is difficult to hide it all away, most of it will be "visible" to the radio signal. With very high frequencies, and their resulting short wavelengths, it is easily possible to hide the entire working length, and thus lose the signal.
Older tech radios are line of sight, but that doesn't usually matter as you need to be able to see your boat to control it anyway. 2G4 is just rather more line of sight.
My home lake (Fairhaven) is salty, being primarily filled from the Irish Sea, but the only problems that any of my club members have run into with signal loss have invariably been traced to a radio whose aerial has migrated itself down into the lower parts of the hull. And on one occasion, the use of a "park flyer" radio. On a big lake, range can be a problem, but anything more than 200 yards I can't really see what the boat is doing well enough to claim to be controlling it anyway.
|Thread: Balsa Model Kits|
Way back, balsa was the only game in town. Since then, we have seen various plastics, fibreglass, and ply become available, all of which do a better job, especially for any manufacturer hoping to sell more than one kit per customer.
Balsa can make great models, but working ones need a lot of work to be tough enough for use by modellers.
|Thread: Building a model from scratch|
Is it being carved from solid?
Is it intended to be a working model (i.e. actually sailing) or a static display piece? Different considerations apply.
|Thread: Model No2 for New RC Modeller|
In that case, the 540LNs sound about right. Top speed of the real thing was under 10mph, a bit of surplus power on the model won't do any harm, but the model going much over 3 mph won't look right.
Steering by differential throttle setting is basically tank steering, but having a mixer involved, either hardware in the boat or software in the transmitter automates the process. It does generally work a lot more smoothly than doing it by hand.
Motor choice is dependant on which of the lifeboat kits that Tony Green offers is involved. Motor choice and the work it (they) are intended to do determines the ESC. Probably a brace of Marine Viper 15s. Not the cheapest option, but cheaper than buying a cheaper option and then going for the right one.
A hardware mixer setup in the boat does improve handling, if the transmitter can do the mixing for you that's a saving on wire in the boat. Most transmitters are capable of binding to more than one receiver, so unless it is intended to sail both boats at the same time, a new transmitter should not be needed.
|Thread: First Person View|
Finding the right type of cable to get a 5.8GHz signal up a mast without losing the signal on the way might be problematical. The usual rules are that you need it as high as you can easily get it without either getting in the way of anything else or having a "quite small) obstruction that will mess with the signal. The higher the frequency, the smaller the obstruction needs to be.
At a laser meeting a few years ago I watched a laser being sailed with the "help" of FPV during the lunch break. It was less than a minute before the bank was rammed. And that was by the then UK Laser champ. It was noted then that FPV sailing needs a crew of two - one to get seasick steering the boat and a trusted mate who can tell the driver where he is and what is off to the side to ensure that contact is minimised.
|Thread: KeilKraft Mermaid|
On a small hull, the weight difference between the plastic rudder hanging off the transom and the weight of the brass lump plus whatever is used to mount it will be considerable..
A jet engine will take air in, then make a huge amount of gas o squirt out the back by burning fuel, giving it lots of drive. A ducted fan, however, only accelerates whatever air it can suck in, so getting a lot of air out the back needs the opportunity to suck a lot in at the front. If Crusader had been running a ducted fan, it would have needed huge nostrils as well. I suspect that DF Bluebirds also tend to have oversize inlets, and the smaller the scale, probably the more extreme the exaggeration.
That is one big, heavy rudder for a very small boat. There are many similar size RTR boats on the market, and often, spares are readily available, because exciting toys get bits broken off.
Googling for the Feilun FT009 spares (because I can remember that one) shows things like rudder assembly and drive parts listed.
Putting a large motor in a small hull and driving it with a large prop gives a problem that Newton predicted. The reaction of the prop being turned in the water results in the prop trying to spin the boat.
|Thread: Prolux S-5009 servo|
While I have formed an abiding liking for drum winches as opposed to arms, I did develop a few mental notes for when setting up arms.
1 To get the travel wanted, there is usually a doubler arrangement. The line, having come through a bulkhead, passes through the end of the arm and then goes off to a point very near the bulkhead entry.
2 To get the best force when going close hauled, you take a line from the bulkhead entry over the servo horn screw head. When the arm is set for the sails being fully in, the hole at the far end of the arm should be on this line. At the same time, when the arm is at the "fully out" position, he arm end should be as near as possible to the bulkhead entry point.
3 The arm puts a considerable force on the servo shaft. Double bearings are good, but mounting the arm under the horn minimises this twisting force.
4 All of the force generated by the sails goes through the arm and the servo to the hull structure. The mount for the servo needs to reflect this. A rough test is to pick the boat up by the line. If it all survives, the mount is strong enough.
The horns that I have run into (apart from mini and micro servos) all seem to be the same size, but some have 24 splines, some 25. Pushing harder does not cause a wrong one to fit. Don't ask.
Edited By Malcolm Frary on 30/01/2021 13:24:24
Edited By Malcolm Frary on 30/01/2021 13:30:03
|Thread: JIF 65|
One practice is to butt join the two edges, tacking with cyano, then reinforce the join with a strip of glass cloth and epoxy. The cloth/epoxy becomes the stringer, and gives a much larger surface area for the join. Probably simpler than shaping stringers.
|Thread: Prolux S-5009 servo|
Most servos are supplied with a collection of horns to fit the splined shaft. Often there is a circular one among them. If the holes in it do not match the ones on the arm, a small drill bit can provide them ready to accept the small screws Any horn with the right diameter hole and the right number of splines will do the job.
My personal preference is to use one of the servo size winches for easier mounting and rigging.
|Thread: Switches and speed controllers|
Fuses generally need more space - you have to get your fingers around them As said earlier, regular insertion and removal does cause the contacts to fatigue.
Switches have two current ratings of interest - one is the current that can be switched, the other is the current that can be carried before the contacts start to heat up. Usually the figure quoted on the box is the switching current.
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