Dad_flyer

That is a point LHF. I have not painted my official brown FT Storch. I did have to do some repairs, adding a skin of cloth with PU varnish. Not water based. That stuck well, I think I lightly sanded first.

Cheap Toolstation spray paint and spray varnish on this. Otherwise I have used artist acrylic, which did not help a model that was already tail heavy.

I think that is telling kc. Also if Chris Foss talked about something similar but does not incorporate it now, and the fact that the collective wisdom of the forum has little memory of it. Something that seemed like a good idea at the time then.

Thank you Frank. Not much information available on the Tempus, but it does mention "the unusual wing profile".

I spend (far too much) time wandering through Outerzone. I came across the Magnum 40 (and 60 and 64 cycle) https://outerzone.co.uk/plan_details.asp?ID=6790 https://outerzone.co.uk/plan_details.asp?ID=10492 and https://outerzone.co.uk/plan_details.asp?ID=11425 It has what I can only describe as a symmetrical reverse cambered wing section. Can anybody shed light on this? Was it supposed to give particular flight characteristics? Or is it another place where at our scale the wing profile does not make so much difference on a sport model?

There are a number of other variables, but most of them come out in the wash. For example: Take a given prop and required rpm, that gives the actual power for the model. On 4s it has a lower voltage, so will draw more current. High current tends to fry things, so you want a high current ESC. Ok, go for 6s. Lower current is good, so smaller ESC, except that 24V takes the next level of capacitor etc and again tends to mean a bigger or more expensive ESC to be rated for 6s. Lower current stresses the battery less, except that for a certain flight time you want a higher capacity battery at 4s and a lower capacity at 6s and the C of the required current comes out the same. The battery internal resistance also comes out in the wash for the same reason. Lower resistance, but higher current at 4s, low current but higher resistance for the lower mAh 6s. Lower current is good for the motor too (except again many are only rated to 3s or 4s, though there is nothing really voltage dependent there). However to turn at the same RPM with more cells you need a lower KV motor. Lower KV has more turns of wire, so a higher internal resistance, which wastes more power. For a given size and weight of motor the longer wire also needs to be thinner, so even more resistance. Going for a smaller prop on 6s allows you to keep the higher KV motor, but small props are less efficient at moving air. If that smaller prop is ok, the 4s could drive it with an even more efficient even higher KV motor. I think the only actual difference, if you start off from a certain prop, is in the connectors and wire between the motor and battery. There the 6s definitely wins. That does assume that the actual ESC, motor with the right KV and current capacity, and battery size are available. In practice one is often starting from a small number of available motors, and we have some batteries. Or we already have a model with motor and ESC installed, but there is not quite enough power. Also this only holds in the 'mid' range of current and battery, which is around this size. ESC, wires and connectors over 60 or 80A are pushing it. But in looking at systems around 600-900W I think it is a matter of taste.

A person would be maybe 16-18" across the shoulders. So that is 3 1/4" to 3 1/2" ish at 1/5 and for two people the cockpit would need to be 7" wide. What does your guy measure?

The C rating of a battery is related to the internal resistance. A better battery will then have less voltage sag under load and drive the prop faster, drawing a higher current. The bigger prop will also make the motor draw quite a lot more current. So with better battery and bigger prop you will be well over 10A static. I have no Idea how much power you will actually need for the performance you want. You could try flying with the big prop and bigger ESC and see where the throttle needs to be for the climb you want, then measure the current/power at that setting, and the mAh you need to put back into the battery after a flight. Then you should have the information to make your ideal setup?

Not very neat (or very not neat) but it will do. Found some aluminium that is the right thickness and should be about the right grade as it was also for something expected to be stiff and flat. It became rather less flat on 18th March 1995 I think it was. But we straightened it enough for the day and retired it when we could get a new one. I don't think I am likely to use it as a spare, so here goes. And as I said, a rather less than square end result, but it will work.

Thank you all. As I cannot find stronger versions anywhere, I shall make one.

I replaced the X-mount for the motor on my foamboard spitfire. After three gentle flights with what I would call good landings I noticed there was a good deal of downthrust. On inspection it is the motor X-mount that is bent. There is not a mark on the prop or spinner so there cannot have been much force. The firewall is only mounted to foam too, so that would normally crush first. This is a replacement from the manufacturer, the material feels fine, but the design has no strength around the inner screw holes. The countersink goes almost through and almost to the edge. Does anybody know a source of better mounts? I think I shall have to make one that is square not X, if I can find a piece of aluminium.

Finally a day with weather for smaller models, so a couple more fixups have flown. Both Mayfly and the Spit are much happier now that they have motors that are straight. Lovely smooth and quiet flying. ? More thrust on the Spit with a proper propeller rather than a floppy plastic one. Mayfly with a more efficient motor and a slightly bigger battery now goes on for ages. I also did a new undercarriage which does not bend on every landing.

Re: laminating film. I managed to pop out to the field this afternoon before the weather closed in again. Took my foamboard spitfire. I am just starting trying laminating film, and I thought it might help the muck from belly landing in wet grass. So before I went I put laminating film on the front underside, and it has indeed made come back without the usual ingrained mud.

I had not thought about that being possible. I shall need to try it, it gives the best of both worlds. My charger will manage 20W which is not too bad, but an increase would be nice for my bigger batteries.

On board telemetry is not necessarily expensive, that depends on the radio system. Otherwise, if you have been able to connect a strobe to the voltage checker the same method could drive a relay or electronic switch instead of the light.

One thing that is harder to take into account is that the bigger motor will have a lower internal resistance. This gives less voltage loss to the internal resistance, leaving more for the prop revs. As an example, I had a model with a 2830 1350kv which gave 9900rpm on a particular prop on a full 3s. Changing to a bigger 3536 1100kv motor on the same prop gave 9800rpm with a partially discharged 3s battery (0.5V lower, which 'should' be another 500rpm) I expect you would find in practice that the Acrowot power train delivers a lot more thrust even though it looks to be similar.

Don't tell him!

I did some TLC on Mayfly this winter, which is on the Dark Nights Fix Up thread. This week I also made up a wire undercarriage. The aluminium one is too much weakened by all the holes that I put in it, and is probably the wrong type of aluminium as well. I dislike bending and soldering as it all tries to spring apart and go off at odd angles. I have done wooden jigs before. This time I had an idea to superglue the parts to a glass plate. That worked remarkably well, it held firm enough even in the fore-aft direction. Being glass I could also line it up square on the lines on the mat underneath. All done. The wheel hubs had started to loosen, so they are glued again as well.

Both videos will play at the same time on my phone. The sound of a twin using inline twins ?. That would suit Child_flyer's current favourite plane, but it would need to be a big one... (CF's picture from yesterday)

It would have been a lovely day at the field today, but we went to Old Warden instead. Grosvenor House going home.

I think David may have been referring to woven polyester (as in lining material) rather than polyester film.

The specifications for the REC14-12 are what should fit the bill well. I use a Yuasa Yucel Y12-12, which is cheaper but not specified for deep discharge (I had not seen the REC versions). Use case is very similar to yours, but less frequently, and I have not had it as long. Still fine, but when I am charging for bigger 4s models the drain rate is fast enough that even as specified the battery delivers only about 8Ah. I have looked for something with bigger capacity, or bigger discharge, or different chemistry - or just buying more lipos. In the end the Y12-12 is at a very low price per capacity point and so anything else would need to be guaranteed to last much longer to be worth it. Some people seem to have a solar panel as well (in photos of groups of models in the pits). That might well be worth it. They should last well, and the continual recharge would help the stress on the main storage battery.

I have adjusted the control runs so that there is now no binding and the servos are happy. The outer hole at the control surfaces and the inner hole on the servo horn gives something over the specified throws. It looks very little on the rudder.

Good work DD. The prop and dummy rotary really finish it off.

Resurrecting a very old thread as I am resurrecting a swap meet buy. Of the Renegade threads on the forum this one has bits about setup. Child_flyer got this for a song, electrified and complete with battery. It has sat out the lockdowns and I am going through checking over. As always, even when you have a model in flying condition when you look closely there are things to fettle. I wanted to replace the rx switch at least. Plugging in a receiver the throws are very large, and the rods are mounted to the end hole of the standard Futaba servo horns. I found a manual on the BH website, which says 10mm for ele and ail, 15mm for rudder. Has anyone here got experience of flying one? Are those low, mid or high throws? There is a bit of moving things required to get the push-rods smooth and the throws right. CG quoted in this thread is 75mm from the manual, and John A flies at 92. The manual I have says 70mm, but can move + or - 10mm to taste. I have not yet checked the balance the previous owner used.