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Member postings for Bob Cotsford

Here is a list of all the postings Bob Cotsford has made in our forums. Click on a thread name to jump to the thread.

Thread: Panic bipe servo advice
19/08/2018 12:35:49

A Panic with 4 aileron servos can be good fun - set up mixes for spoileron on one wing and flapperon on the other so each wing goes opposite to the other for the mother of all crow brakes. Another mix is all 4 ailerons linked to the elevator for looping almost in it's own length. I never got round to coupling ailerons to rudder to try using the top wing ailerons as airbrakes in knife edge but I bet it would work to tighten knife edge loops.

Thread: Super rare Rojair kit - Pre production ME109 with slight fire damage
19/08/2018 12:24:12

just - WOW! Silk purses from sows ears ain't in the same league.

Thread: Power Safe for any receiver
19/08/2018 12:18:04

£58 for Futaba fittings - isn't that getting away from Chris's initial idea of a cheap and simple universal power bus?

Thread: C of G Which way up and why?
19/08/2018 12:10:51

I can see some logic in the tail-wheel lifters idea. If you lift the tail then at some point the CofG will be vertically above the main wheels axles and the tail will feel weightless as the model reaches equilibrium. On some airframes you probably could judge whether it should be safe or not. I don't think I'd use that method myself!

These days I use an Mpx balancer, and as others have said the model goes on the opposite way to how Chris' first post suggested. I always thought the slightly nose down bit was to get the wing at roughly zero incidence, this being a throwback to the days of freeflight cabin jobs.

Edited By Bob Cotsford on 19/08/2018 12:12:06

Thread: fav model of all time
16/08/2018 16:32:04

I'd almost overlooked the QB20L I'd had late 80s or early 90s, powered by a nasty 25 - Taijet maybe? - that was quite a nice little GP aerobatic model, quick and simple to build and car boot sized.

Thread: No Luck. Thunder 180.
15/08/2018 20:09:28

I would hesitate to say it's normal, but let's say that it's not uncommon. Foam isn't the most stable of materials, but it has to be said some brands are better than others. Me? I'd get the wing square to the fuselage and adjust the wing root to suit. I think it's a slow-fly 3D type model so compromises or inaccuracies won't be the end of the world.

I think it may be worth ASKING the shop about it, they may be able to check a few other examples to see whether 'they all come like that Sir' or not.

Edited By Bob Cotsford on 15/08/2018 20:12:38

Thread: Sweet sweet epoxy resin.
15/08/2018 20:02:07

I usually use white wood glue to attach the tailplane these days, my preference being Evostic Resin-W. Slow setting and as strong as anything for wood to wood joints. PVA isn't the lightest of glues but it's a damn sight lighter than epoxy.

Thread: Great Service - But!
15/08/2018 11:39:00

Standardised postage provisions, standardised packaging - it's all aimed at reducing p&p costs (including labour for picking and packing) overall for the business as a whole which benefits the 'average' customer whoever that may be. I've had just as bad from small model shops too. Hardly ecological with all that plastic left floating around. The small bubble stuff makes a good protective mat for the model assembly workbench but you can only re-use so much of it.

Thread: CameronWood654@gmail
14/08/2018 09:27:31

I got an email from the above address asking for pictures and price for an ASP engine that I'd sold through Classifieds some time ago. I sent him a link to a Google search for ASP 120 images and got a reply with the usual spiel about not being able to collect but his shipper would take care of the details once his cheque has cleared, including transport and maintenance costs.

I thought about stringing him along a bit more but it's just too much effort for too little reward.

Watch out, they're still out there!

Thread: OS 120 E four stroke Engine
10/08/2018 22:10:35

The ASP 120 is a good engine but from my experiences with that and one of the OS's, the OS will beat it both on output and carburation. My OS would turn a 16*8 APC quite happily while my ASPs were better on 15*8, the OS was easy to tune for a smooth throttle action, the ASPs were harder to setup for a smooth midrange transition. The ASPs were still very good engines just not as refined as the OS.

Thread: Why not 'cut and glide'?
10/08/2018 11:56:22
Posted by Martin Harris on 10/08/2018 00:20:08:

More than no reason why you shouldn't leave the throttle open a touch - more a case of why don't we set a "flight idle" on our electric models? I hate to see electric models (especially scale ones) taxi out, stop their props while completing the turn into wind and restart after a second or two for the take off run. Maybe a bit "anal" but I always make the effort to keep the prop turning and some of the comments in this thread are prompting me to doing a little programming along these lines (although in general, my scalish models tend to be IC powered). It will be interesting to see if there is a noticeable difference in fine control of the flare...

That thought had occured to me too Martin, particularly for some larger foamies which seem to stop dead in the air on closing the throttle. In the past I've set an 'idle up' on one or IC two models where they showed a tendency to go deadstick after particular manouveres. Time to try it on a leccy.

And yes, it does look odd when a scale model taxis out then the prop stops prior to taking off!

09/08/2018 13:57:22

Possibly blown wing effect comes into it but I think the propwash over the tail surfaces has more bearing on how a landing turns out. One of the issues I've encountered in converting from glow to electric on 40-120 size models is the dramatic loss of thrust you get on low throttle with electric compared to glow which has resulted in me making some pretty heavy landings due to lack of elevator sensitivity at the flair combined with a sudden loss of airspeed. I could cope with this on a glow deadstick where I know I need extra airspeed, but I'm still recalibrating my mind to the poor low end throttle response on electric. I need to follow Jon's lead and add some throttle curves!

Thread: Lanier-Giles 202
08/08/2018 23:24:53

Well, I can only speak from empirical experience, and while I'm sure your calculations are correct I have had two 9 gm or so microservos fail in flight, not to mention those with stripped gears from ground handling accidents. Neither failure was in a large or high powered model.

I hope that you do prove me wrong and that your model has a long service life with them. Me? I'll stick with slightly meatier units for all but lightweights just for peace of mind.

08/08/2018 17:20:32

I'm with Nigel, perhaps I should have been more explicit as there are micro servos and there are micro servos. I would be looking at metal gear micro servos around 12-14 gm with 2 kgcm of torque as an absolute minimum. 9 gm plastic gear servos may be ok on park-fly foam models but I don't think 1 kgcm is up to the job. Back in the day those Waltron etc servos were barely up to the job on a good day using minimal surface deflections. These days models frequently fly faster and have larger control surfaces. Can you not get your hands on some HS225BB, MG14 or similar?

Thread: Seagull Mosquito Laser build
08/08/2018 09:23:53

If there are thin areas in the moilding then slap on a layer or two of 1oz glass cloth before cutting. My cowl cutting method is to drill pilot holes in the corners (1.5mm works well) then join the dots with a Dremel cutting disk.

Thread: Thinking of changing my car
08/08/2018 09:17:18

As someone who has recently wasted his time doing all the comparisons between brands I think that it's fair to say that there are only two three factors to consider - size, cost and does it light your fires? There's little to choose between big brands, the real differences are how the manufacturer hides the cost, ie what is part of the package and what's an option.

Just like buying a new transmitter you will recognise the benefits in what you are familiar with and notice 'defects' in the unfamiliar. Next up - Spektrum wars- best since sliced bread or pile of poo? Answers on the back of a £10 note please.

Thread: Vintage Rc small Piper Cherokee lookalike - Plans?
07/08/2018 19:39:03

Pilot did a Cherokee kit which matches Tim's description right down to the stick on windows. Mine survived a number of years abuse overpowered by one of the cheap Far East 25 clones that were around then. The kit wood was a bit iffy resulting in a model that was heavier than it needed to be, but it still flew well.

Thread: Is epoxy the same as mustard?
07/08/2018 09:42:27

I was in a similar position being on a support rota Old Geezer. Users were an inconsiderate bunch and seemed incapable of understanding that if I finished gluing up a fuselage before sorting out their IT needs then they could get in an extra tea break. Managers were even worse, seeming to think that being on-call should take priority over having one more flight.

As for epoxy, I've got quite good at judging equal small quantities of resin and hardener and little goes to waste. Someone pointed out recently about the PU skin and I've since rescued two half bottles of Gorilla by breaking up the skin with a piece of wire.

07/08/2018 09:31:40

Jim Drew on his RCGroups thread said that his X10+ decoder uses the S-Bus frame rate, and that as this is always 9ms for FrSky his X10+ outputs servo pulses at 9ms intervals. My first experience with SBus was using it to drive retract doors in a Macchi 200 usin FrSky decoders, it took me a few smoked analogue micro-servos to get the message that it's safer to just use digitals with SBus!

06/08/2018 13:14:54

Chris, I've not had any problems in the past ordering one or two units at a time. The ones I have are V1 which is essentially just a different board layout. Since giving up larger models I find myself with a couple of units going spare if you'd like to have a play. PM me your address and I can pop one in the post for you to try out.

When I first came across the XP boards the Bangood offerings weren't available, neither were redundancy receivers so this was ahead of the game at that time.

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