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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: Majestic Major (electric) build.
22/10/2018 17:10:00

Oy! I'm just big boned, my Mum told me so it must be true laugh

22/10/2018 15:53:01

That's what you get buying second-hand!

22/10/2018 15:28:46

Sullivan also do sets with metric fittings, as I recall they used to be gold adaptor/clevis for imperial threads and silver for metric. I use the Gold'n'rods a lot but I've had a few where the pins hadn't been riveted into the clevis. Easy fix, bin the clevis and buy some that have been riveted. I can't remember the details, they're on this site somewhere, but I saved a few ounces on a second-hand J60 by simply changing the servos from 148s at the rear of the radio compartment to HS225s at the front and dswapping heavy wood dowel pushrods for snakes.

Nigel, brake cables can just be fixed at one end as they are only put under tension and it's the pull that counts, not the precise position and movement at the drum end. As we are more concerned with position than with force (compared to brakes!) we need to use intermediate anchors to stop the outer flexing as the servo pulls and pushes the inner.

This was what I found:

Posted by Bob Cotsford on 10/11/2016 17:52:39:
Posted by Bob Cotsford on 02/11/2016 11:04:18:

1/2lb = 8oz=~240gm. Say a conservative 3:1 moment ratio for the effective position of the pushrods - wonder if the two 10mm pushrods plus 2mm threaded rods each end in mine weigh more or less than that 80gms? Might be I could save that much lead just by going closed loop! It will be interesting to see.


As near as I can make out on the kitchen scales the complete fuselage and tailplane weighs 4lb 11oz at the moment, so my target is to beat 4lb 3oz.

Edited By Bob Cotsford on 02/11/2016 11:08:14

Now down to 3lb 10oz for the fus and tailplane! I can't believe how much weight I could shed so easily - swap the pushrods for a snake on the elevator, closed loop rudder, 3*148s in a plastic mount behind the CofG replaced with HS225BBs under the tank and move the lead to the front of the cowling. The pushrods actually weighed 2 1/2oz - 75gms, the replacement Sullivan snake just 16gms, let's say 20 allowing for a balsa brace halfway up the fuselage and the closed loop for the rudder, then the standard size servos fitted behind the CofG were another 5 1/2oz in the wrong place. Those two changes have saved a lot of lead up front It will be interesting to see how it flies now.


Edited By Bob Cotsford on 22/10/2018 15:32:31

Thread: ASP anybody?
20/10/2018 19:23:56

The end results of some of my flying I think 'mole' should be in there somewhere face 1

Thread: Electric Cars.
20/10/2018 19:20:31

I do feel sorry for coming generations. In years gone by I used to enjoy driving and riding bikes just for the hell of it. Admittedly it got harder to find clear stretches of road so a trip to the coast turned from heaven to hell, but there were always track days available as a different way of enjoying a motor based experience.

Cars are heading in the direction of functional transport units with travel something to be endured. Just as well they will be self driving to allow the freedom to find other entertainment during journeys. Maybe the current youth are being well trained with their noses stuck in some form of screen throughout the day.

So I book a transport unit, load up the models, program it for the field - will it divert down the farm track? How does it close the gates on it's way out? Then at the end of the day I book a like unit allowing time for it to find the flying site, cart all my gear to the gate and wait in the hope it arrives on time. I'm sure leisure uses will have been included in the grand plans.dont know 

Edited By Bob Cotsford on 20/10/2018 19:21:51

Thread: The jeti DS12.
20/10/2018 19:04:06

If I were buying now I'd go for the X10. in it's favour are smaller, lighter, better battery system following comments on that used in the X12, TWO internal aerials and I find I hardly need the screen as telemetry and timers can be read out during flights so it's position is not an issue. The X12 does come in a very nice case though.

Thread: Acrowot foam e new fuselage - What glue?
20/10/2018 18:56:19

UHU Por, it's what it's made for. I've not used aliphatic on EPO but as it's primarily a rigid drying wood glue I don't think I'd go there. Gorilla Pu - if you can clamp the halves firmly together and don't mind the mess give it a try. I use Gorilla for repairs where the parts no longer fit together as it expands to fill gaps but it also gets everywhere that you don't want it unless you mask everything off.

Thread: ASP anybody?
20/10/2018 13:58:18

Posted by leccyflyer on 20/10/2018 11:30:52

:......I rarely see a glow-powered model these days, it;s mostly electric or petrol at the fields that I've been at in recent years. ...

I would say that of 4 local clubs one is 99% ic including turbines, one 80%+ ic (mostly glow), one exclusively electric and my club is probably 60-70% glow power. Electric is on the rise, no doubt of that. I would say that many of the electric flyers are older members who don't want the hassle or just plain can't cope with the ic support gear.

20/10/2018 10:25:11

I have to admit that I did have to supress a smug grin yesterday as a couple of flyers knelt in the grass puzzling over recalcitrant glow motors. Then I got drawn in to the discussions of what to try next to get them going. Yes, glow motors are messy. Yes, they need more field support. Yes, things go wrong. But yes, they are also fascinating pieces of engineering and are very satisfying when you get everything right. They have sound and a soulfulness that is lacking in electric models.

And no, I won't be going back to glow in the forseeable future!

As for the 46 being discontinued, could it be because the 52 is such a logical choice that there's not much demand for the 46?

Edited By Bob Cotsford on 20/10/2018 10:25:59

Thread: Fun with Foam Board
20/10/2018 10:13:54

The enthusiasm of (relative) youth and their very own golf course to run riot on, what's not to like? Can they tempt the younger generations away from their screens? I hope so.

Thread: The Bunt
20/10/2018 09:16:43

I think problems occur most often (at least for me) because of a fear of the ground. As you reach the bottom of the bunt speed is increasing and you automatically push harder on the stick causing the model to drop a wing, ie screw out. This is made worse because we're concentrating on the elevator while also trying to add throttle and worrying about the ground so it's easy to allow the ailerons to wander.

It can help to use a lower rate, trust the model, it will happily fly around an outside loop if you let it - provided it has power to pull it round or airspeed to carry it. As an offbeat example of an exception to the rules, my Fugly will complete a sort of bunt despite daft amounts of down elevator. It actually goes round in a series of stalls and recoveries resulting in a 10' diameter threepenny bit without any tendency to flick or roll out - low aspect ratio rules, ok? Weird and unsettling the first time, but this tubby little model pulls itself round every time.

Thread: Electric Cars.
19/10/2018 10:14:50

David, aren't watts a measure of instantaneous power? 40KW is what - 53hp? Your calculations seem to be based on all those 31M cars running at slightly over half throttle 24 hours a day, or am I missing something? Similarly, your charge requirements then equate to a steady charge over 24 hours so I don't think things are that simple or that bad. You are correct though, the first requirement is to cut down the number of cars on the roads. I'm afraid that will have to be down to other road users though as I NEED to drive a single occupant AWD SUV in order to get my model planes in it and to negotiate the field in winter. Sorry but there it is.

The subject of electric cars was one point on the news this morning with the usual calls for the Government to step in and do something. Excuse me, but didn't we tie the Gov. up trying to extricate us from binding agreements with our neighbours in the EU, and isn't taxation (which funds HMG) a prime bone of contention with many objecting to current rates never mind the hikes that will be needed?

As I see it EVs are at the stage where the brave and bold are providing beta testing for manufacturers while the technology evolves, so praise goes to those souls currently acting as guinea pigs. If the technology matures during my lifetime I will happily embrace it, God knows I know what the effects of inhaling rubbish for decade after decade can be. I would happily have gone EV but Motability don't seem to be getting behind the concept so I'm driving a Euro 6+ motor instead.

Thread: Marutaka / Royal Beech Craft D17 Staggerwing Kit
18/10/2018 19:33:23

If it's any help I've sold 60 engine sized Pica and TopFlite kits for £80-120 but then I'm cheap whether I'm buying or selling. I've seen the same TopFlite kits as the ones that I sold going for £180-200 on various selling sites.

Can you be sure it's complete? If you're not prepared to guarantee that, that fact and the damaged cowl will knock it's value down. Personally these days I'd advertise it at £150 and sleep happy knowing it's what I would consider fair. For a quick sale ask £120. If it's maximum cash you're after, ask £200 ONO. If you feel lucky put it on E-bay with a 1p start and see where it goes. List it for 30 days though to give time for word to get around.

What did annoy me was to see one kit I'd sold on an £80 offer because the buyer reckoned he'd been searching for one that was at a later date being advertised for £160 on the BMFA classifieds! I guess the buyer fell out of love with the model once he'd looked at the plan.

Thread: Program transmitter for m60 help
17/10/2018 10:20:41

It would help if we could be sure what equipment you are actually using. It sounds as though you have FrSky gear, an X10 transmitter and at least one X4R receiver. I don't use the FrSky OS but I can tell you how I set up OpenTX.  I guess the first question is what colour is the X4R? I believe it should be white for the 4 channel version or black for S-bus. As long as you use channels 1 and 2 either should work ok for what you want.  Which channels are you using?

I've just found a youtube guide via google, unfortunately in a foreign language but it all looks simple enough.  Select 'airplane' 'flying wing' and that looks to be it.

You might want to get this moved to the FrSky area of the forum.

Edited By Bob Cotsford on 17/10/2018 10:34:50

Thread: Wot 4 MK3 Classic
16/10/2018 22:34:20

Hmm, hidden radial drives?

Thread: LiPo dimensions
16/10/2018 15:02:57

Watch out for the C rating too, higher C packs tend to be both larger and heavier. Back in the GiantCod days 3S 2200 packs varied as some of the manufacturers started adding packing between cells, presumably to aid cooling, so you could get two packs with the same C rating which were the same weight but one would be thicker than the other.

Thread: Flair Puppeteer wing fixings
15/10/2018 19:36:12

Mine appears to have been cobbled together with the ply plate embedded slightly behind the leading edge. This leaves about 1 1/2" of dowel sticking out of the front. When I get round to the Puppeteer I'll add a plate as per Martin so that the dowels are loaded in sheer, at the moment any load is a pure bending moment.

Thread: Panther Trainer Autogyro
15/10/2018 16:38:08

or, as I put it to Sarik, they have supplied me with a kit for a very fast, prop driven car.

15/10/2018 15:49:45

Point of interest, Sarik are now showing the short kit (plan, laser cut parts + additional wood pack less rotor blade material angry) for £81, a significant reduction from the £129 shown when I ordered mine 3 weeks ago teethangryface 8

I have emailed them about the lack of rotor blade material and untimely price drop, not to mention their packaging.

Thread: Flair Puppeteer wing fixings
15/10/2018 15:44:45
Posted by fly-navy on 14/10/2018 20:33:21:

Bob why not use some threaded inserts into existing holes in wing, you can always epoxy them in for peace of mind. I use these now more than captive nuts. Gaydon in a couple of weeks should be some there.


That's the plan John, I get my inserts from Modelfixings. I've used them for ic radial mounts in the past when I couldn't access the rear of the bulkhead and for electric motor mounts too.

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