mfin

Well, got it going. Ran it up, the photos below are middle-ish throttle and with no adjusting yet really.   So to recap for anyone who was interested or helped, what I've ended up with is a RCLine SoftSwitch with the red wire cut on the servo (£13.99) and the Pump is a Ripmax flight box pump, a rectangular dark orange thing (£7.95) its driven by a 2600Mah 4 cell 4.8v Vapextech battery (£5) I've taken various plugs off things that mismatch and soldered up the wires of course.   I have a swicth harness inside which so that I can charge up the battery when its in the house. There's then the little switch which belongs to the SoftSwitch (I put this on the side of the plane). Its connected to Ch5 on the 'gear' switch on the transmitter.   As far as the plumbing goes, a 3 line tank (a Dubro 6oz tank with gasoline bung) has two vents to the top (so I can fill - cos otherwise venting or filling won't be possible cos there's a pump in the way of course). The supply to the muffler (pitts style which already had smoke capability) comes from the pump... BUT at the front of the plane there's a fuel t-piece on which (once filled with fluid) one of two vent pipes goes onto and hence sends loads of the fluid straight back to the tank without putting any strain on the pump motor. The other vent pipe is just that and lets the air back in, no pressurizing needed of course.   Just after the t-piece (on the last bit of tube to the muffler) I put a little clamp that I could tighten to restrict the flow even more and tightened this by eye till a little dribble was coming out. (I did think the clamp would be needed on the return vent tube off the T as too much would go back to the tank but this wasn't the case - either way the pump can do its job without any extra pressure or load created on of the tubes).   I can now tinker with that clamp to let more or less through no problem and can get to it at the back of the cowl no problem at all (its a little 'wire' clamp which was £1 from a hardware store) ...same as I can get to the t-piece to remove the vent/tank return pipe when I need it to act as a vent pipe whilst filling up.   This is the first test only PLUS it was WAY TOO WINDY to actually fly (20-25 mph)and a lot of smoke was blown away but its obviously working. This is using plain DIESEL from the garage... I've heard diesel/paraffin mixed works well? I think Id have smoke at this delivery rate for maybe more than half of the flight time.   Oh... extra smoke battery is in the engine boxing under the cowl, diesel tank is on the C of G and pump behind the C of G (figured this is a good balance as pump and batt weigh similar amounts).   First looks... but I'll post back and maybe get a bit of video up somewhere once I get it up in the air...   Thanks all. PHOTO 1: SMOKE OFF (and engine running of course)   PHOTO 2:  SMOKE ON (same mid throttle position - windy day as well)          

Yeah, just have an experiment with the % of negative expo, when you look at the movements on the surfaces as you move the sticks you can see/feel the effect, I can choose by eye on the ground and normally get it about right first time. (my fliton had suggested expos in the manual as a start point so you can see this is pretty normal).   Its best not to completely over-do the neg expo cos you'll end up getting used to massive movements then and that's not going to help your skills in the long run. It all depends on the plane you see. On a trainer you wouldn't really need any but it might not hurt to have little bit, just try things.   Rule of thumb with Dual Rates on a 3D model for me is one rate at 100% and the other at 60%. (Thats % of available surface movements if you're with me).   Now this means you can 'follow the book' building 3D models in your early days and setup the model with its intended massive throws (normally everything thats physcially possible) which you'll need for 3D but use the low rate to just fly and get used to it. (You could even put one in at say 80% and one at 40% for getting used to it in the air - note I'm talking 3D capable models here). Then, when you're used to it you can use the higher rates.   These kind of things should have you flying very capable 3D models quite easily. I've seen people take up models with high throws and no expo and find it very difficult to keep in the air, as a novice you could be looking at its last moments as it leaves the ground in that instance.   Get someone else to look at your throws and response too. I think now you've looked at it you'll get to know and you can always ask to waggle the sticks of other planes on the ground to see how they compare but you will find there is no wrong and right and people have things as they want. For instance I know people who have Extra's like mine who just want to fly circuits and so the odd loop and roll so I won't be interested how they've got it setup cos I want to throw mine around.   Anyway, happy flying.            

Yep... I think the only thing is now that Ive run it up in the house is that even with 4.8v the pump is shifting loads of diesel. I put in a load more fuel line to slow it down but its still too much I think.   I've got a 3 line tank (supply to pump from clunk and 2 breather/fillers) so I think I'll try putting a t-piece before the muffler now and connect the filler line to that t piece so that a lot of the diesel just goes back up that tube to the tank... I've got a good idea of how much flow is right (from previous experiments blowing it through) so I'm going to try this to lower the supply a bit. I can always crimp this return line a bit  with a clamp of some sort if too much goes back to the tank.   I was going to just crimp the fuel line to the muffler a bit, but that's more 'bodgey' cos doing that in order to just increase the resistance of the supply tube to the muffler would put unnecessary strain on the pump motor. (tried squeezing it and it didn't sound too happy).   Of course the other solution is to use say a 2 cell battery and really undervolt the pump, but I haven't got much lying around... saying that, I might have something... will tinker again with the above if I get the chance.

Ahh... GOT IT!!! Snip the red wire, the world didn't end and everything seems to be behaving perfectly (watch this space).   I found that the thing has a BEC (Battery Elimination Circuit) in it and you can disable this by disconnecting the red servo wire to the receiver.   Right, bit of plumbing now and I'm away, I'll post back when its done and tested. Thanks to all so far !!

Hi again.   Well, digging through I 've simplified things potentially. Ive got an RC Line Soft Switch (18A) here and have wired this up and it drives it fine.   It has battery + and - (ive put a 6v batt on) and motor + and - (obvious) and its servo lead to go to the receiver   BUT... theres always a problem isnt there!!! ...when its plugged into the receiver it's the Soft Swtich's battery (the one connected to its battery terminals) that powers the receiver and the rest of the servos through being plugged into channel 5!   If I then plug my existing battery into the reciever as well it all gets confused and doesn't work, not that I thought it would.   SO... how do I modify the servo wires to the Soft Switch so that it still gets the right signal from the receiver to tell it what to do but doesn't try to give it power?? Diodes or something or cutting wires?   Any pointers? I'll have this in the air tomorrow weather permitting if this is something that can be solved easily.  

Ahh... thats a useful thing to know Timbo, I couldn't imagine how that would have been done till I saw it.   Maybe I'll have a little experiment with that and use that same 6v battery to run the smoke pump. If the voltage drops to a certain level the relay will only stop anyway so nothing critical will happen.   I quite enjoy tinkering with stuff like this.

Ah, I see, but if I ran a separate battery for that, which would be no problem at all then which of the three wires on the servo would I have to connect to this battery. Cos of course at the moment its all just coming from the receiver isn't it. You lost me a tiny bit!

Sorry Chris are you saying just connect it to the flight battery or chuck it in and not have it turn on and offable??? Either way is not quite what I want.   Timbo and that, got a couple of relays, one looks too tiddly as its only rated to go to 2A/24VDC which isn't a lot, its slightly smaller than half an oxo cube...   The other one I can see the wires inside look more like it and that one is 2x1x2 cms in size and will cope with 8A/240VAC so it would be fine and is only the size of a mini servo.   BUT!!!.... I wired it up and checked it, (just using multimeter set to beep at circuit across the outputs) and whilst it works fine in the first instance it soon drops my 6v battery down to early 5s and the relay starts buzzing as the volts cant hold it anymore. I don't get that, I can't see how it can drop so quickly (or do they normally drop quickly from being used)... perhaps my relay's not sapping anything much out of the ordinary at all and I just need a relay that'll behave down to 4volts or something?   I can't see how a relay that requires 6v DC to operate could draw that much current, or is the modified servo doing it? I'd expect to feel heat everywhere or something?    

Ripmax trainer will be fine, keep it cheap (I had one and it was fine), get a multiple servo deal, get something like a Just Engines Jen 47 in it (if you get the trainer 40). Something like that will get you flying and have a good bit of power to spare. Most ARTF trainers are much the same just pick the one you like the colours of.   Only tip is if you get one with tricycle undercarriage like the Ripmax and you fly off grass then don't bother connecting up the front wheel steering, waste of time, it'll break or cock you about, just secure it pointing straight forwards.   If you prefer something better looking (in scalish sort of way) but at a few more quid what about a Graupner Taxi Cup II? See on AlsHobbies, just set it up with not too much throws as it is a little more 'capable' than some trainers. But, bear in mind you could crash it. Why not get the Ripmax and if you smack it but have improved then see if you are confident enough to get something else. (Im assuming  if you crash it the engine and electronics will survive, depends on the crash but a lot of times they do!)   If you can't afford 2.4Ghz get 35MHz and don't worry about it, don't bother with s/h non comupter based ones though, you'll out grow it wanting other features for your second and third planes most likely. I got a Hitec Optic 6 and its still got pretty much everything I need years later.

Well, I've got a Y Lead Reverser ordered now! Thanks all.

No... think about it, if you're looking down on it and you spin the servo 'around the arm' it will still spin the same way as nothing will have changed. If I pulled the arm off and turned it round 180 degrees then yes it would work, but mechanically it would be ever so slightly different. Ive done this in another plane but I offset the servos in height up the fuselage to compensate and negate the slight mechanical difference, but with this model I wanted it totally the same and never considered that I might want the channel used by the second elevator servos for something else.   The model flies perfectly, I just have both servos on two channels (2 and 5) but I want channel 5 back for something else so I want them both running off a Y-lead on channel 2.   If you follow then one of the servos has to be reversed. So a Y-Lead with Reverser built in seems like the only easy bet. Otherwise if a simple answer had come back I woulfd have modified one of them and then used an ordinary Y-lead.

Timbo - sorry are you saying that you can just swap black and red wires 'to the servo' cos I heard you should not do that so thats why I didn't try it. I don't know why but I heard it makes servos burn out?   If you were refering to your original suggestion of 'rewiring of both the pot and the motor' then yes I agree it should work BUT the motor is soldered directly to the pcb you see, so there's no nice and easy wires to swap.   Um, frank.... here you go, a photo of each side, imagine the servo going clockwise and you'll see it'll so the opposite effect on each one. I could 'flip the arm over' but mechanically it won't be identical and symetrical and at the moment it is absolutely dead on.      

Bruce - na, they are totally mirror image, thats the problem, so they're opposite. I have another plane where I offset them so I could have one horn pointing down and the other up if you know what I mean but this way it doesn't work ....I had to stand next to it and turn both clockwise for a second and look which way each elevator went to double check I wasn't being a dunce!   Ken - No, one will operate backwards, see above.   Timbo - Yeah, now I'm thinking its not actually that easy (not like just swapping black and red on the lead for example).   All - I think my friend must have had a bad experience with a reverser... they wouldn't make them if they weren't reliable and doing a proper job. I'm going to order a JP servo Y-lead Reverser all-in-one and give it a go, only £7.50.   Reason I'd asked is £7.50 is still £7.50 and p&p to add too and I have to wait for a couple of days, nevermind, I'll get there.

Thanks all so far.... I can't do it with my radio, I have a Hitec Optic 6. I have two aileron servos on 1 and 6 and two elevator servos on 2 and 5.   I want channel 5 back free to use for another function (it can be used for a switch function normally) and if I just 'y-leaded' the elevator servos to free up ch5 then one will be working the wrong way.   My only other option is to use a reverser I suppose... or... rewire the servo in some way... I know if it was digital I could re-program it to be reversed but its not thats why I was asking cos, one I'd have to buy a reverser, I can see people also do Y-leads with a reverser built in for 'one side' ...and secondly Id seen someone else's plane misbehaving on the ground with a reverser but I guess they do their job properly and he was just unlucky!        

Thats okay, by the way, if you don't already know then have a look if your transmitter supports exponential which 'desensitizes the initial stick movements effect', well, thats the easiest way to explain it, you'll find it in the manual. (Exponential can do the opposite too but I can't see why anyone would want to do that so don't do it by accident !!). Now, with 'negative' expo dialled in on a 3d capable aircraft (in the region of 25 - 40% for elevators and ailerons, and a bit for rudder), flying is much easier. Plus, you should use dual rates so you have a choice between full movements for slow stuff like 3D and lesser movements for thrashing around at speed.   If you don't have a transmitter that supports this stuff (its quite basic) for some reason, then get one first and use it, it'll give you loads more confidence and could well save an aircraft (I think if Id maidened my Extra for instance with 'no expo and on full rates' I might have been in trouble! certainly wouldn't have been 'relaxing').   Hope some of that helps.   By the way, this is all down to how good you are. But what I'm saying is if you flew my Extra today in the right settings you'd be fine if could already fly a trainer well. By well I mean to a level of dealing with dead sticks easily and had already mucked about bombing it around, rolling and looping it and laughing at how its rubbish and difficult it is to try fly upside down. At this level then you could fly my Extra on no problem whatsoever, in fact, Id say in complete confidence that it would be as easy or perhaps even easier.   I think some of the oldies come from a time where neg expo and dual rates didn't exist, let alone the fact that artf's didnt and you might have spent 100 hours or more building something. Nowadays its easier and there's loads of 3D stuff out there, and it hurts your wallet if you crash something but not much else.   In very little time, say, one good summer you'd get past the possibility of crashing something and be totally confident. At that point it'll be things like engine and mechanical failures that are the things most likely to write something off!! ...hope we get a good summer now, cos I wanna learn how to lower down in a prop hang as I can do it for yonks but even if I go into a 'wall' at head height (look that one up on youtube) I end up with it slowly creeping up!   There are people out there who just like to get stuck in too you see. I still find it a thrill, I never wanted it to be dull, if it did get dull then I'd probably pack it in as Id get nothing from it!