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Leccy Lanc XI

Started by Wiz, February 09, 2006, 13:35:59 pm

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Wiz

Time for a new thread ...

For reference Leccy Lanc X
The buck stops here.

lavers

Welcome to Leccy lanc XI, Haven't got anything to say just wanted to be the first on the new thread :ev

John

Gordon

February 09, 2006, 17:43:25 pm #2 Last Edit: February 09, 2006, 17:47:57 pm by Gordon
sod it!  :ev

Gordon

....and it's my 1600th birthday too!  Double sod! 

On the plus side got me a rather nice little hard drive camcorder yesterday, so once I find out how to work it AND get myself a website you can all marvel in DVD quality video how many bits can fly off a Spit when it crashes!  ;)

BD, you've got a website haven't you?  How do I go about getting one...preferably for very little effort and cash!  :af

BalsaDust

Hi gordon, hhmmmm websites - a little bit of a can of worms - of the how long is a peice of string variety .....

Your ISP may offer personal webspace as part of the costs you pay to access the internet. Check with them to see if they do - you may have some already allocated but just don't know it !

AOL do this for example.
This route will also come with a domain or web address you can use, say www.gordon.aol.com

The other option is to go and buy some space from another company and believe me there are plenty out there.
You pays your money & takes your choice.
I use Webmania who offer a good deal as far as I can see. Certainly suits me for my purposes ....

You also need to register a domain name ... gordons-going-to-fly-his-lancaster.com .... or whatever you choose!

There will be some technical stuff to do to link the domain you register with the webspace you buy, but it is straightforward and help is usually on offer from the company concerned - or here of course !

You'll need a program to create the website on your PC or MAC and then a program to upload the pages to your webspace.
There are packages out there that do both jobs, but hunt around. Keep an eye on PC magazine cover discs for some freebies ....

here endeth lesson 1


regards
BD

Walts

Treble sod it john ! I have never started a new thread and i did have something to say, not that it amounts to much as usual ;D ;D

Anyway firstly Steve, I think the UK dealer for Eurokit is Ripmax, you could try a search of their page. Also the foam wheels were just something i grabbed of the shelf in my local shop. Have long since thrown away the wrappers, never use the things normally, but i guess they were supplied by radio active. sorry i can't be of more help :)

Guys, i stepped out the front door this morning and it was blowing a gale >:(Then remembering Lee moor has its own weather system, i thought blow it , Ill take a chance on it being different down the Field. When i got there it weren't a lot different, but having dragged the misses along with the video camera i thought i might as well try some taxi trials. I was wrong about the field, its still as rough as ever, and was quite soggy from some rain 2 days ago! and the bl@@@y wind. Well basically i done 3 runs, each time it struggled to deal with the sheep's foot holes and turfs of grass. the second run showed promise with the tail comming up and the lanc bouncing along nicely, had to cut it cos even if it did lift off' it wasn't going to clear the fence!
The 3rd run was as sluggish as hell but i noticed the port leg leaning in. As i cut the throttle the whole tail wheel assembly ripped away including the access hatch behind it! Sod it , i thought thats enough :( On close inspection the main leg collapse wasn't that bad, it was just the weedy mounting screws that had pulled out, with no damage to the structure. I reckon she will fly but its going to have to be of a hard runway or very perfect grass, and the climb out is going to be critical! Anyway the damage is all repaired and the extra 1/2lb of mud cleaned of the tyres ;D Just looking for a suitable site :-\
Cheers Walts

gyronuts

Gordon..third thread and it still hasn't flown!!
Maybe this year? Bill
PS how is the spit going.

lavers

Walts,
a good effort on the lanc run up, at least you've found out a few things, like an overweight model lanc makes a good dragster ;D
I'm fairly confident that mine will fly I'm only waiting for the time, weather and availability of the flying field, apart from that I'm ready to go :af

Having a few probs with the C of G on the whirlwind though ??? The plan suggests a  C of G and to make it balance I'm having to put a ton of weight in the nose and it just goes against everything I've learnt in electric flight :-\
I'll put it to the forum and see if anyone else can advise.


Gordon, Looking at the weather forecast for sweaty sock land and I don't think you'll be flying the spit this weekend :'(


John

Walts

February 10, 2006, 09:55:11 am #8 Last Edit: February 10, 2006, 10:08:11 am by Walts
Hi John, having to add weight to balance a model is always a horrific thought, and on an electric model double horrific :o But the CofG is probably the most important factor in a models stability and flyability. So if its needed i would definitely add it! Unless you can remove the weight from the tail of cause  :af

Cheers Walts

gordon#1

QuoteGordon, Looking at the weather forecast for sweaty sock land and I don't think you'll be flying the spit this weekend
.....yup!  Gonna try and fly the trainer though!   :af

Gawd...I've been demoted....who's this Gordon#1 guy?   :co

Gordon

I'm back and promoted!!  Just a weird setup...I log on via SWMBOs user area and I'm Gordon#1 and from mine as Gordon.  Weird!!!

Walts

Blooming eck! Gordon talking about promotions I've only just noticed the dizzy heights you've reached.How did you manage all those posts? i remember you when you was a mere junior officer, I'll have to start putting 'Sir' on the end of my post's ;D ;D

Walts Opps sorry Sir!

Gordon

February 13, 2006, 16:50:33 pm #12 Last Edit: February 13, 2006, 16:56:16 pm by Gordon
Hi Bill, how's tricks? 
QuotePS how is the spit going.
...last week the reply would be "vertical"  ;D 

Me a Sir?  Nah Walts, me ex-SNCO (aka Sgt)....could never master all those knives and forks on the table!  :ww

Just taken my trainer out of mothballs and got it ready to fly again today...methinks I need some more confidence before flying the Spit again!  :co

lavers

Is that vertical up or down Gordon ;D

Walts

Some sound advise needed guys. As my lanc is obviously struggling, i was wondering wether i could go to 10 cells to give that extra bit of poke, or will this smoke the motors, which i can't really afford. The weight difference can be compensated by removing the dead weight in the nose, what do you think?

The set up is 4x multiplex 6v geared motors with the supplied props (same as Gordon's) all wired direct to the battery terminals, is this parallel ? With a Jeti 50 amp speed controller. I have no way of checking what they are pulling, but as this is the same set up tony N. used, with the same battery (sanyo 2400 ni cad) I would presume they are pulling around 32 amps as per his original.

Walts

lavers

I think you will be heading for a fall with that much power Walts. You might get it into the air for a short while but you are going to create a lot of heat in the motors and controller which isn't an all round good thing to do.
I tried the same thing and my speed controller would heat up and cut out after about three minutes. (50amp controller 7.4v 480 BB's)

There's quite a bit spiel on the Ripmax spit thread about what power a can motor can handle, some say aye some say nay, whatever 12v is a lot to put across a
6v motor.

I put 11.1v through two speed 480 BB's at the weekend and they gave out a serious smell of burning :o

I'm sure someone will come up with a more technical explanation but I'm sure the answer will still be no,

Regards

John

SteveM

Walts,

Some time ago, I mentioned that I met Tony N with the prototype of his new B17 design. Stupidly, I did not take notes but I recall the model used Li-Polys with 'ordinary' geared Speed 400's and he said there was bags of thrust even though he was using 3-blade props.  Now what voltage he was using I cannot precisely remember but I recall that it was a considerable degree of over-volting per motor.  He said something like "Remember it's amps that kill motors not volts".  I was hoping that the RCM&E build article would have come out by now with details of exactly what he used, as I would copy for the Lanc.  Despite that front page photo on the cover of the mag a month ago, it has still not appeared.

I'm sure that there must be a physical law that prevents you from pumping more and more volts into a motor and getting something for nothing i.e. getting more power (VxA) by increasing volts without increasing, or even decreasing, amps and I suspect it is something to do with propeller choice, but that's as far as I go - hence let TN explain it!  I agree that if you are replacing useles ballast with batteries, that is a very tempting route.

Steve

Steve

Gordon

QuoteIs that vertical up or down Gordon
....guess John?   :ev

Walts...gotta agree with John about your voltages, as 12v with a 6v motor will fry it.  I've a 9.6v supply with 6v motors and they work fine.  Remember that you'll drop approximately 1v due to the pack's internal resistance(s) so really it'll be 11v across a 6v motor (this assumes you're wired up in parallel?).  My lanc is wired in 'twin' parallel (the inboard and outboard motors are in the same parallel circuit). 

More speell to come but it's mealtime now!!

Walts

Keep it comming guy's I'm all ears :)
The ultimate truth is I've just built her too heavy, and am now trying to find some way of dragging her fat butt into the sky :(
As i mentioned earlier my first attempt showed some promise, but the conditions were all wrong. Pot hole'y soggy mud and sponge wheels are not the ideal recipe for take off, ever tried running flat out in a bog :D But i had convinced my self that was the day, and stupidly tried anyway :-[
Getting back to the point, even if she did pull her self from the mud, i think things would have got very hairy.
Steve, I've heard that about amps not volts killing motors as well, on the other hand 12v does seem a little excessive on a 6v can as john said, so still indecisive.
So.............Keep it comming guy's I'm all ears :)

Walts

BalsaDust

Hi guys, your right to say that it is amps that kill motors.

but remember its the load on a motor (in our case the prop & gearbox) that determines how much current the motor will draw. What you can't do is force amps through the motor, it's the other way around.

With that in mind, the key here is to select a prop that doesn't draw too much current.

The limit for a can motor of the type we are all using is around 12A with plenty of airflow over the motor to keep things as cool as possible.

As for voltage, the 4.8v motor has the highest RPM/volt figure of the S400 range so is ideally suited to gearbox and duct fan applictions. Its quoted max voltage is 6v. The 7.2v motor has a max quoted voltage of 12v.
I can't find any data on the 6v motor, but expect it to be somwhere in the middle of the other two.

I have been running a direct drive 6v motor on 9.6v quite happliy now, for some time with no problems. You could try 10.8v (9cells) with a 6v motor, but check the current draw before you fly .....

regards
BD


Smark

I was about to suggest trying 9 cells myself BD. I think 10 cells will be too much.
I'm using standard 6v cheapo cans powered by an 8 cell GP3700 pack and she flew well a few months back with 7x6 props. I've actually just upped the props to 8x6 APC 2 bladers and having run the thing flat out on the deck for 5 minutes, the 50 amp ESC and the wiring coped ok. I did this to give a bit more thrust as my finished lanc now weighs bang on 6lbs (5.5lbs when she flew) and also as a result of modifications I made to the multiplex gearboxes which has allowed me a greater choice of props.
Gordon, John, Walts et al, if I remember rightly, you're using the multiplex boxes too? Well my various attempts at different spinners / props is a real tale of woe which I wont bore you with but in the end I took out the gearboxes and modified them. This has transformed them in terms of smoothness and delivery of power. No more vibes and bent shafts. I posted the details on the Priory Lanc build thread if you are interested.
She's now ready for action. I think I'm going to fly her off a runway as our club field is a bit soaked at the moment and I don't want to rip out the u/c. It's just finding the time now. I'll let you know how she goes.

Gordon

Walts...the excellent gen re BD etc assumes the 'bigger battery equals larger voltage' approach.  Nothing wrong with that.  However, as my removable tail assembly is heavier than the standard build I quickly realised that the 'standard' 9.6v 3300MAh NiMh that BD had nudged me towards wouldn't be heavy enough to balance out the model, even with the battery crushing the bomb aimer into the nose blister!  I opted for a USA-bought 9.6v 4500MAh 'square' pack that balanced out the model perfectly.  That way for a little more weight I'm going to get a bit more duration, which if not ideal is at least a satisfactory compromise.

John.....have you thought of that idea to get rid of the lead weights in your Whirlybird?   :ww

lavers

Walts, in a nutshell you need an amp/wattmeter to find out what amps the motors are pulling with the extra voltage. No matter how much voltage you put through it you're still going to need about 50 watts per pound to get it off the deck.

failing that give me the size of your props and I'll get some idea of the amperage on motocalc for you.

Gordon, I've just filled the whirlybird with 8 oz of lead to balance her out. That still gives me over 100 watts per lb so don't know what I'm worried about, just don't like putting lead in a plane is all :)

John




Walts

Hi guys
        Thanks for all the input,The multiplex 6v motor, is if i remember, most efficient at 8 amps. So assuming my set up is pulling 32 amps total from the battery, same as tony N's set up, then it would appear 32A x 9.6V= 307W divide by 7.5lbs =41W as opposed to, if his model weighed 6lb 51W. So the weight issue is telling me that this power train is not going to fly this model no matter what i try and do!
Incedentally whilst trying to find the priory lanc thread i got side tracked as you do, and found the "will it fly thread" by R101.The set up was completely different, with B/L motors, but the short of it is the guy has made a 70" beau at around 7lb and was initially only drawing 30A total. He was told not to even try and fly it! the out come was he managed to change various components and ended up with 250W per side, 500W total giving 71w/lbs. It now flies well and there is a nice landing approach pic on the thread.
Basically guy's i think i am looking at a whole new power train for this one. So perhaps you can start throwing some motor suggestions at me ;) Possibly some cheap brushless set ups, what do you think???
BTW John the prop that fits the multiplex box is a 17.5x16cm, but as i say i think I've over stretched the trains capabilities :-[

Walts

BalsaDust

Hi guys,
my Lanc is flying at 49W/lb - it has been said that she flies too fast for scale, but that is in part due to the 6.75lb weight rather than 5lb giving a higher wing loading. Indeed I can throttle back in the air and the model will still fly, so the W/lb figure will have reduced to say 30.

In my view the W/lb figure is only a guide and not a rule that should never be broken. The key thing is how fast the props are turning at full throttle. Once you know this, the pitch speed can be worked out, giving a top airspeed. For the Lanc you need to be around the 36mph mark or better. With 8x6 props that works out at 6500RPM - which strangely enough is the figures for my Lanc  :af

Check your setup Walts before any changes are made and use that as a guide.

regards
BD

Walts

Hi BD & thanks for that, My brain really starts to hurt when we start talking technical jargon. But it looks like i really need to get a watt meter and tacho, then i can give the info to you guys to work out for me ;D Whats the most cheapest, reliable unit(if there is such a thing!) that i can get with out risking a divorce ;D

Cheers Walts

BalsaDust

Hi Walts, I use a "JP MicroTacho Tachometer (Pocket Size)" which you can get for around 17 squid

I bought a meter from Hillcott electronics (50A FSD) which I wired up myself into a box - 14 1/2 squid

A wattmeter is a nice piece of kit, but you don't absolutely have to have one ...... If, on the other hand, you do, then you'll need 50 squid - give or take a few tentacles ......

regards
BD

Walts

Cheers BD, I'll look into it. My bits have just turned up to finish my camel, so I'll get back on that for a while :)

Cheers Walts

CraigO

hi fellas, moved threads again i see.

i am using the 4.8 Volt motors wired in 2 two parallel strings of 2 motors in series from a 10 cell pack.  this limits the voltage to each motor to about 6 volts and it is working fine.  i am flying for up to 9 minutes off a 10 cell 2400 pack and once in the air i can throttle back to about 2/3 throttle.  I am just changing over to a 3 cell lipo pack cos my 2400 packs are dying.

craig

Walts

Hi Craigo
          Long time since we spoke, What happened to your mossie, did you finish her, is there a thread ???
Guy's guess what its my birthday to day, and what a great day its been! The wife bought me an RCV90sp and a retract set, so i've now got all the hard wear for my warbirds hurricane(next build) On top of that i got £90 from family, so been out spending like a kid in a sweet shop.
I got a watt meter, a tacho meter, and some other goodies. so once i fit the plugs to the meter i can give you some precise readings of what's going on.
The instructions are brief, but say connect one end to battery and the other end to the motor. Do they mean speed controller, is it o.k. to do this?

Cheers Walts

BalsaDust

Hi Walts - yeah, just put the meter between the battery and the ESC and you'll be fine

regards
BD

Walts

Thanks for that BD,
                Thought i had some spare 4mm gold connectors lying around, but can't find them. I'll get some more tomorrow and give it a go.

Walts

Gordon

February 18, 2006, 00:39:30 am #32 Last Edit: February 18, 2006, 11:32:13 am by Gordon
Walts....Happy birthday ye ol' godger!  SWMBO had another 21st birthday today too...spooooky!  :co

Who's this Craig guy anyway????   :ev

Walts

Cheers Gordon, Hope your wife had a good day too :)

Guys I've run the tests with the watt meter, and some suprising results. The volts were showing at only 7.8V  at full chat, but were returning to near enough 9.6 at tick over.
The amps were settling around 37A at full chat.
I tested the RPM with a JP mini tacho, and they were showing 6300rpm at full chat. The battery warmed up fairly quickly (only a short test)
These results would give a W/lbs of only 38.5, not good!

The model weighs 7.5lbs
Motors Multiplex sp400 with gear box
Props 17.5x16cm
ESC Jeti 50A
Battery Sanyo 2400 9.6v nicad
All motors wired individually to ESC (parallel ?)

Any suggestions on how to improve the watts guy's :(
Also should the voltage be dropping this much?

Cheers Walts

Gordon

Hi Walts...yes she seemed to enjoy her day. 

As for your test.  Your parallel set-up only differs from mine in having a smaller battery.  I had used a 9.6v 3300MAh pack and got 8 minutes at max chat.  The voltage dropped a volt in that time and I THINK I got about 45w/lb.  Really your snookered on changing the props, as those multiplex units are stuck at 7x6.  As your lanc is pretty much the same weight as mine that would account for the small difference in w/lb you found.  The 6300 rpm sounds very close to what I got (my No3 seemed to run at 6200rpm with the rest around 6500rpm).  So really Walts it appears to be working as advertised.  Could you chuck out the brownings and save any more weight?   :af 


BalsaDust

Hi guys,
looks as though something in the circuit does'nt like passing 37A, hence the voltage drop. This could be the cells, but the Sanyo 2400 packs are generally quite good. Other places to look are the wiring and connections to the ESC.

4mm gold connectors are good for 60A, so those should be OK. Have you brought all 4 pairs of wires to a common point, then extend the wiring from there to the gold connectors ? If you have, then this wire needs to be able to pass 37A rather than the 9A or so to each motor. 4mm or 5mm, 1000 strand wire would be OK for this sort of current. 1.5mm wire or bigger is the size I'd use to the motors.

In high current circuits, the fewer joints you have the better and those you do have, need to be good ! - any dry joints in the wiring could be causing the drop off in voltage, due to a joints high resistance. A joint like this could get hot and fail - not something you want to happen in flight !

If any wiring is getting hot, it could catch fire - unless its silicone sleeved ......

One other thing to try is greasing all the gearboxes to make sure they're running at their best. Probably won't make a huge difference - but worth doing. might up the RPM a tad ....


regards
BD






Walts

February 18, 2006, 18:56:40 pm #36 Last Edit: February 18, 2006, 19:09:50 pm by Walts
Cheers guy's
              Gordon, i really can't get the weight down no more with out stripping back to the wood and lite spanning, which probably wouldn't make that much difference anyway :(
BD I was thinking of the points you raised, I cant remember exactly what the wire was rated at. But i know i got it from Maplin's, and made sure it would cope with the system current(probably rated around 40-50A) its quite chunky and i used it to all the motors, then soldered all the ends together with a single piece of the same stuff comming out of each joint, with a 4mm gold connector to the ESC (+/-) I didn't have/still haven't got a very good iron and i remember the joint being difficult to heat up. So one possible area to look at again.
The other thing is the battery got hot very quickly, so might suggest that it is struggling to supply the current, hence the voltage drop, like you said. But whilst the sanyo 2400 is good at delivering power (my reason for using it) I believe most good batteries are only guaranteed to give up to 40 A, so 37A don't seem that far off, or should i expect more from this set up.
Your thoughts please :)

Cheers Walts

p.s. when bringing 4 wire's together like this and adding a 5th out wire to the joint, is soldering the best method. Or would you recommend something else?

Walts

I ran the motors again to night, much to her on the settee's annoyance ;D
I checked everything during the run, and the only thing that seemed to get hot was the battery, and we are talking very hot! with a really short run.
I've been reading other threads and on one, a guy was running 2 sp400's off a 9.6v 8 cell, and he said it was pulling 25Amps.
Now doe's that mean by running 4 i am trying to pull 50Amps, hence the voltage drop??? I believe that the sanyo2400 is probably struggling to deliver :-\
I noticed that puffin's are doing some high flow 3300 & 3500 that are rated at 60A &70A. Do you think that by using these hi flow packs & letting the motors draw what they want with out resistance, would bring my volt's back up and give me more like 46-50wlbs. After all the sanyo, whilst good in its day, was probably never meant to be drained by 4 sp400 simultaneously  :-\ What do ya think???

Walts

CraigO

i know i am a stranger, but things is busy :)

yes i did get my mossie finished.  and it is a treat to fly, except that i dumb thumbed it on take off about 8 months ago and it i still havent finished the repairs :(  i have no idea how to attach a pic now but i will do so when i do.  I am now working on a 262 and going a lot crazy doing it.

i would be surprised if you are pulling anything like 50amps.  if you are then your speed 400's wont last long they realy dont like being much over 10A each.  the other thing is however that you will draw more amps on the ground running staticlly that you will in the air.  what sort of ammeter did you get.  mine is a tong style that just clips around one of the battery leads and detects the current flow throught the wires by the EMF that it i set up.  i now also have an Emeter that plugs into the circuit.  i have run 2400's up at 60 amps before and yes they will get hot but they should be fine.

cheers

Craig

Walts

Hi Craig
       I haven't got a clue how to post pic's either, i get my misses to do it, think she does it via a host she says the admin. shouldn't mind as it saves them server space ??
I'd like to see your mossie sometime :af
As for the battery, if it can cope with the amps draw, then i need to look at that dodgy solder connection(as per BD's advise) only thing is I've buried it under the retract valve and servo mounting plate >:( what really concerns me is i don't think the voltage should be dropping to 7.8V as soon as i start the run :o So something is definitely putting up a resistance and dragging down the volts.

Cheers Walts