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January 22, 2019, 20:46:33 PM

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Author Topic: Leccy Lanc XI  (Read 168203 times)

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Offline lavers

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Re: Leccy Lanc XI
« Reply #40 on: February 20, 2006, 12:17:38 PM »
Have you tried another battery Walts? before you go about undoing bits and pieces check to see if you get the same drop with another battery.
John


Offline Walts

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Re: Leccy Lanc XI
« Reply #41 on: February 20, 2006, 14:54:40 PM »
John yes i tried my Sakura 3000NiMH, and that was even worse, you could see the voltage ticking down like a stop watch! mind you i don't think they are very good batteries. I was considering getting a puffin high flow battery, but if there is a problem with the circuit it wont help :-\

Cheers Walts

Offline BalsaDust

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Re: Leccy Lanc XI
« Reply #42 on: February 20, 2006, 17:56:50 PM »
Hi Walts, will check my model tonight and post the current/voltage at full chat. Its not a test I've done before - I know the current, but I'll let you know how the 3300 NimH's are handling the 28A current drain

regards
BD


Offline Walts

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Re: Leccy Lanc XI
« Reply #43 on: February 20, 2006, 18:46:39 PM »
That will be interesting BD, also how did you get 49W/LBS if your battery is a 9.6x28Amps/6.75lbs that would =39w/lbs, or have i got my figures in a twist again :D

Walts

Offline BalsaDust

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Re: Leccy Lanc XI
« Reply #44 on: February 20, 2006, 21:26:54 PM »
Hi Walts

Quote
how did you get 49W/LBS if your battery is a 9.6x28Amps/6.75lbs that would =39w/lbs

that'll be because I'm running at 12v  :ev

which, by the way, falls off to 10.8v or thereabouts under load - I wasn't expecting that :o

The off load voltage of the pack was 13.8v, which points to a drop of 0.3v per cell under load. A quick bit of maths and your cells look about the same or maybe a bit better than mine ....

so it looks as though your drop off is normal .... I guess you could add an extra cell to your pack without too much of a weight penalty and bring the voltage under load up a tad.

What's yours like Gordon ?

regards
BD

« Last Edit: February 20, 2006, 21:36:39 PM by BalsaDust »


Offline Gordon

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Re: Leccy Lanc XI
« Reply #45 on: February 20, 2006, 22:28:24 PM »
Quote
What's yours like Gordon ?
..............too late tonight for a run, but I'll dust off the lanc and run her tomorrow night  :af

Offline Walts

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Re: Leccy Lanc XI
« Reply #46 on: February 20, 2006, 22:33:11 PM »
Wow!
     Really appreciate you testing your lanc BD, saves me ripping things apart and still ending up with the same results! On that I think I'll post a question on the Puffin thread and see if John thinks the high flow cell's will help, or wether going to 9 cell's might be the answer as you have mentioned. As it would seem the best thing i can do is to try and raise the volts, as they form part of the equation for w/lbs.
Cheers again

Walts

Gordon, know what you mean after the ear bashing i got last night ;D

Offline Gordon

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Re: Leccy Lanc XI
« Reply #47 on: February 20, 2006, 22:55:44 PM »
Quote
Gordon, know what you mean after the ear bashing i got last night
...wot, u mean I need a reason?  :ev :ev

On a positive note....as your lanc is wired in parallel the motor 'killer' amps will split 'equally' (or as near as damn it), but I'd be careful your motor and battery voltage differentials don't get too large (my 6v motors run fine on the 9.6v 4700MAh pack....really 8.6v when it leaves the battery).  I say be careful since your battery voltage will be 'seen' by all of your motors!   :ww


Offline Walts

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Re: Leccy Lanc XI
« Reply #48 on: February 20, 2006, 23:33:44 PM »
Cheers Gordon, really having trouble getting my head round this leccy stuff. Re your point about differentials, that is why i am trying to find away of getting more usable voltage out of the 8 cells rather than adding more cell's. As you say you are getting 8.6v to the motors from your 9.6 pack, a drop of 1v,.  which i thought was the norm. but my pack is dropping nearly 2v. With the little knowledge i have managed to retain, i understand that if too many amps are being pulled from the pack the internal resistance will cause the voltage to drop.I don't really want to add more cell's, because when the meter is first wired into the circuit with 8 cell's it shows 10.4 v, once the throttle is opened it drops to 7.8v. so if i put another cell on it it would initially show around 11.5v which i am thinking might stuff the motors before they get the chance to get going and pull the voltage down to say 9v. this could be complete tripe, as i say i have trouble with this leccy stuff. Anyway I've posted a question to John on the Puffin thread, see what he thinks............Its too late to be babbling like this, I'm orf to bed.

Walts


Offline Gordon

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Re: Leccy Lanc XI
« Reply #49 on: February 21, 2006, 21:45:52 PM »
Walts...ran the lanc tonight but my car battery wasn't up to charging the lanc's battery, so 24 hour delay while the car battery is charging...!  :af

Offline Gordon

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Re: Leccy Lanc XI
« Reply #50 on: February 22, 2006, 11:27:35 AM »
Quote
Cheers Gordon, really having trouble getting my head round this leccy stuff
.....!

Walts.....for our 4 motors:

Parallel Circuit.......Voltage constant, current divides into a quarter for each branch. 

Current will be a quarter of the supply current and will be the same amperage for each branch (as each motor in the branch is assumed to have the same resistance as those in the other branches).  We know they'll vary slightly but to all intents etc etc...!  So each motor 'sees' the full supply voltage but only a quarter of the current.

Series circuit.....Voltage divides across each motor, so it varies throught the circuit.  The current stays constant in all areas of the circuit.

The supply voltage is divided up 'almost' equally across each of the 4 motors (we know they'll be slight variations due to motor resistances varying).  Each motor gets the full supply current but only a quarter of the voltage....hence my preference for parallel circuits!   :af

Offline Gordon

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Re: Leccy Lanc XI
« Reply #51 on: February 22, 2006, 22:53:48 PM »
Walts...ran my lanc last night and tonight....got your problem!  My battery fell to 7.1v almost immediately and at 235 Watts maximum, that was no good at all.  Battery was warm and got 8 minutes out of it, but going to recharge it tomorrow as it may be because it's been lying unused for a while and needs a couple of good runs!   :'(

Offline Walts

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Re: Leccy Lanc XI
« Reply #52 on: February 22, 2006, 23:20:17 PM »
Right Gordon, I think I,ve got that bit :af

Now, i found an interesting article in a mag i read last night which contradicts my last post. This guy asked the editor a question about this very lanc he was building, he was basically trying to get more duration, but the editors answer went off into many different aspects. The bit that interested me was his explanation of 6v motors and the advantages of gear boxes.He was basically saying that by adding a gear box a 6v motor will run quite safely on up to 10 cells, provided it is propped to draw no more than 10 to 11 amps and given adequate cooling.He said that you say, the plan states using sp400 6v and 8 cells, the editor said this is very common in direct drive applications but if you use gear boxes you could go to 9 or even 10 cells, and achieve an increase of 25% more power.He said another advantage of using geared motors and high cell counts is that it allows us to capitalize on the fact that motor efficiency rises slightly with increasing voltage, so slightly less power will be wasted.
Now i know Lavers had some trouble when he tried to use 10 cells, but i believe he was using 2 480 motors, which if they weren't geared could have been the problem, as this guy said you cant use 10 cells in direct drive Co's the props would have to be so small they would be useless. Can't remember John, was you using boxes?
Anyway, just a thought for the day. :)

Cheers Walts
« Last Edit: February 22, 2006, 23:27:48 PM by Walts »

Offline Walts

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Re: Leccy Lanc XI
« Reply #53 on: February 22, 2006, 23:24:18 PM »
Just saw your post Gordon, This would indicate to me that the batteries we are using cant handle the drain of 4x sp400 hence the voltage drop. which is why i am thinking that maybe with this sort of voltage loss i could up the cells and the motors would get nearer 9.6v. especially after reading that article last night. I am still waiting for an answer from Puffins, I think i read somewhere that their high flow cells could handle large ampage draw while maintaining near enough full voltage. So i think I'll either try these cells, or more cells next :af

Walts
« Last Edit: February 23, 2006, 13:09:42 PM by Walts »

Offline Gordon

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Re: Leccy Lanc XI
« Reply #54 on: February 24, 2006, 13:00:22 PM »
Walts...wot's cheesing me off is that the pack can deliver the goods....it was run a handful of times last year and it produced about 340 watts!  Baa Humbug!  :-\

Offline Walts

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Re: Leccy Lanc XI
« Reply #55 on: February 24, 2006, 13:04:11 PM »
Gordon, get your butt over to the warbirds sound thread, It's awesome!! :D

Offline Walts

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Re: Leccy Lanc XI
« Reply #56 on: February 24, 2006, 13:57:56 PM »
Sorry about that Gordon, i allowed myself to get over excited, it wont happen again, i promise  :-[ ;D ;D

Re the battery situation, i am still waiting for an answer from Puffin's, Suppose i should phone him really.My thought patterns at the moment are that my Lanc probably wont fly on the cells i've got if i go up a couple of cells and the motors end up letting out the smoke, then its cheaper to replace sp400s than to lose the whole model to an under powered climb out :o

Walts


Offline BalsaDust

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Re: Leccy Lanc XI
« Reply #57 on: February 24, 2006, 16:27:45 PM »
Hi guys - that warbirds thread has prompted me to get my sound system on the bench again ...... When I first built the Lanc I made up a unit that replayed sampled Merlin sounds ...... hadn't at that time got it hooked up to the thottle - but after reading that thread, I've just figured out how to do it ........

BD diappears into workshop, stage left ........


diappears ??? - that conjours up a very different image ......  :-X


"disappears" is what I meant to say  ;)
« Last Edit: February 24, 2006, 17:22:31 PM by BalsaDust »

Offline Walts

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Re: Leccy Lanc XI
« Reply #58 on: February 24, 2006, 19:21:58 PM »


BD diappears into workshop, stage left ........


diappears ??? - that conjours up a very different image ......  :-X


"disappears" is what I meant to say  ;)

Yes, quite BD, i did wonder if your work shop doubled as some sort of sani-tank for the elderly and infirm ;D

Offline Walts

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Re: Leccy Lanc XI
« Reply #59 on: February 25, 2006, 19:47:36 PM »
Gordon
        I spoke to john at Puffins yesterday, Not good news I'm afraid, i explained to him what i was trying to achieve, but when he heard the weight of the model he just kept saying jeeps! Being a throughly decent sort of chap he said he was reluctant to sell me anything as there was nothing he could guarantee would work. I told him i thought a couple more cells might help, but he said everything else changes with the voltage, and said again he couldn't think of any set up (affordable) that would work. he spoke to me for a good 20Min's but concluded with his reluctance to sell me a thing! obviously his reputation means more to him than a fast buck,My respect to the man for that, but I'm still stuck with a non flier for now :(

Walts

Offline Gordon

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Re: Leccy Lanc XI
« Reply #60 on: February 25, 2006, 22:22:14 PM »
Walts...might have to modify the lanc from a B1 to a B111?  Remember they had a similar problem with payload and altitude so the Merlins were upgraded to Merlin XXs. 

The aircraft configuaration never changed, so neither does your model.  The geared 400 motor setup is now known to be suspect, so brushless appears the only reasonable alternative?  I think the biggest advantage of brushless would be that you wouldn't be stuck with 7x6 props like you are with the Multiplex setup now.  I wonder if running through the figures on MotorCalc would give you some idea of the way ahead?  Taken in tandem with LiPos you will probably get your weight down and a more efficient use of the Watts...gonna cost though!  :co 

Try it with a 7 pound model too...maybe mine needs the B111 treatment?  ;)
« Last Edit: February 25, 2006, 22:26:26 PM by Gordon »

Offline Walts

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Re: Leccy Lanc XI
« Reply #61 on: February 25, 2006, 23:33:19 PM »
Hi Gordon
           I did concider the brushless option when i bought those cheap b/l motors off E-bay late last year. I bought 2 plus a 60A tower pro b/l speed controller, they are intended for my ME110 when i get round to it. Trouble is I've only just learnt that you can't run 2x brushless motors off a single speed controller, they have to have their own. So that would mean 4 B/L motors &4 speed controllers for the lanc, not to even mention the battery requirements :o
Mind you I'm quite impressed with the motors, they are rated at 1.5-18A and 7.4-14.8V so a bit of scope to play with.
I've been using my new toy's to measure them and driving one through my 9.6V pack, with a normal 10x6 APC prop it is only pulling the battery down to 9V and only drawing 11amps. loads of thrust and runs forever with out getting silly hot, so potential to play with more cells and bigger props. (i love that meter) I will use them in my ME110 but will definitely be being very careful with the build weight this time :af

 Walts

Offline Smark

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Re: Leccy Lanc XI
« Reply #62 on: February 26, 2006, 00:08:22 AM »
Gordon and Walts, if you modify those gearboxes, you're no longer restricted to those 7x6 multiplex props. The APC8x6E props I'm now using give bags more thrust than the old 7x6 Mulitiplex jobs. As well as being larger, I reckon they're much more effcient. According to Motocalc, they should be drawing about 48 amps at the peak but test runs show the 50amp ESC seems to cope.
As for the weight situation, I dunno. There's no point crashing some nice models. Perhaps you could hang them up for a while, let technology race along, watch prices tumble and eventually buy a power system that'll do the job. 

Offline BalsaDust

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Re: Leccy Lanc XI
« Reply #63 on: February 26, 2006, 09:37:26 AM »
Hi Walts, done some headscratching ....... your model is 12oz heavier than mine, running smaller props.
Now I reckon my model would fly with some extra weight - it certainly isn't marginal in flight !
I wouldn't like to say how much more though, but if it were say 6 oz's and you were able to lose 6oz's then we'd have models of the same weight  :af

Right then, firstly, is there any way at all that different props could be fitted to those gearboxes to get more power?

I certainly agree with Smark that different design of props of the same size perform very differently ..... you may find that an APC-E 7*6 would work very much better than the MPX one. That said I would try and get to an 8x6 though ..... Is there a metal shaft under the plastic of the main gear that you could fit a prop adapter to?

the other route is to lose weight - Wheels and battery are probably the only option. How heavy are the wheels?

Which servos are you using? Are any "full size" ? I'm using the Ripmax SD200's mini servos throughout. Could you swap to the micro 4g servos on the market at the moment ( I'm thinking retract servo here ....)

Do you have a separate Rx battery? I do, but opted for the smallest size I could get - Its one from a cordless housephone and is very light.

One other thing I thought about was the weight of wire running to the motors. I think the wire you're using could be overkill and you might be able to save a couple of ounces here by using different wire .....

It would be an interesting exercise to work through these things and see how much could be saved ...

Brushless would give better efficiency and more power, but lets face it, the cost @ around even 60 per motor/ESC is prohibitive ....

regards
BalsaDust

PS - just checked wheel/battery weights - my model first flew with wheels that weighed 1 3/8 oz each. I'm now using some that are 7/8 oz each
The original battery was a 10 cell 1700 pack which weighed 1lb 1oz. The 3300 pack I've used since the early flights weighs 1lb 7oz

So I can say that since my Lanc first flew it's increased in weight by 5oz to its current AUW of 6lb 12oz

Food for though there me thinks ........

« Last Edit: February 26, 2006, 11:31:43 AM by BalsaDust »

Offline Dave_S

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Re: Leccy Lanc XI
« Reply #64 on: February 26, 2006, 11:06:29 AM »
Dave S in West Oxfordshire

Offline Gordon

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Re: Leccy Lanc XI
« Reply #65 on: February 26, 2006, 11:40:35 AM »
Dave.......
Quote
Have you Lancaster builders seen this yet?
.....now I have...groan, looks nice, with all our comments taken on board I bet Tony?   ;D  At 35 that's half the price that Nexus were selling it for too?   :af

Smark.....
Quote
Perhaps you could hang them up for a while, let technology race along, watch prices tumble and eventually buy a power system that'll do the job. 
.....started that already!!   :ev

Walts (aka fellow Lanc B1 owner!!)...going to run mine again today, as I'm convinced my pack has the power to get her airborne...eventually!  :co
« Last Edit: February 26, 2006, 11:45:38 AM by Gordon »

Offline BalsaDust

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Re: Leccy Lanc XI
« Reply #66 on: February 26, 2006, 11:47:30 AM »
Hi guys,
OK Walts here's one for you ....


what about going down a cell to a 7 cell pack ?

No really I mean it !

You could change the 6v motors in the MPX units to the Graupner 4.8v motors I'm using and run them from a 7.2v pack ... That would reduce your weight and I reckon the RPM figure would go up as the 4.8v motor is hotter than the 6v one ...

Or of course you could go on to ebay and start all over again  :D

regards
BD

Offline BalsaDust

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Re: Leccy Lanc XI
« Reply #67 on: February 26, 2006, 11:49:02 AM »
Hi Gordon !

Offline Walts

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Re: Leccy Lanc XI
« Reply #68 on: February 26, 2006, 14:20:21 PM »
Hi guy's
        This is great so many new ideas being banded about!
Steve, how frustrating is that! seeing a new and improved version of what we have been struggling with for the last 2 years >:( Still i like his use of 'MY' vac formed cowls :ev certainly would have saved me a lot of work & favour scrounging :D

Gordon, re charged my battery as well, just about to test it again, but I'm not holding my breath!

BD (in the words of Gordon) Oh mighty guru! I am still buzzing with the thoughts of smark's and yours last suggestions, and have been messing with a spare gear box. I reckon that by cutting the castle off the main gear and using a longer drive shaft, i will be able to add a prop adapter to it, get it to exit the cowl in the same position and fit any prop (APC8x6E?) i like to it,have to re-figure the spinner fixing though.
Mind you i don't know what the extra amp draw will do to my battery duration though :-\
I think I'll try this option first ;)

Cheers Walts

Offline Walts

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Re: Leccy Lanc XI
« Reply #69 on: February 26, 2006, 15:08:11 PM »
O.K. Gordon
              I've just re ran my motors, having put the battery on a slow over night charge.Surprisingly things have improved. I don't ever run the motors for more than a min. at a time co's i read somewhere this will do them no good, but the initial run figures were up quite a bit with thebattery hot off the charger. Volts initially showing8.4 & Amps 42 giving a w/lbs of 47. But these rapidly reduced to 7.8v &37A again. Is this normal, when people take these 2 readings to get their w/lbs do they only concider the initial figures and ignore how rapidly things change???
Walts

p.s. I think I'm still going to play with the gear boxes though.
« Last Edit: February 26, 2006, 16:32:14 PM by Walts »

Offline Gordon

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Re: Leccy Lanc XI
« Reply #70 on: February 26, 2006, 19:25:08 PM »
Boy, this thread is busy again!  Ran my lanc and still not getting the watts I used to get...she's down to 34W/lb!  Battery was charged to 4750MAh and took 2 hours 20 minutes, since I discharged it first.  Voltage dropped to nearly 6.8v in about 60 seconds...just not right that!  Amps were averaging about 32A.  Pack was really hot and you could smell the plastic covering.mmmmm??  Now going to charge my GP3300MAh 8 cell pack and run it, as I know it's a great pack for the Spit.  Good idea about the shaft on the gearboxes BD...mmm, sounds like you might have some mileage there Walts and the lower volt motors sounds a cheapo way to go too?  :af

Quote
Hi Gordon
..Hi guru...we're getting our tuppence worth out of you right now!!   :ev
« Last Edit: February 26, 2006, 19:30:07 PM by Gordon »

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Gearbox modifications
« Reply #71 on: February 27, 2006, 01:21:00 AM »
Gordon and Walts, before you attack the gearboxes, have you read my post on the Priory Lanc build thread? I describe my gearbox modifications and there are a few photos attached. It's certainly worth doing. It has transformed my Lanc in terms of smoothness and power and i can use a variety of props. In my opinion, the MPX gearboxes are, in standard form a bad design and are inherently weak. The shafts are only 2mm. The new shafts in mine are 3/16" and are running in proper phoshpor bronze bushes (not brass tube). Due to all the material removed, there is no weight gain according to the digital scales. 

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Re: Leccy Lanc XI
« Reply #72 on: February 27, 2006, 10:00:23 AM »
Walts,
Quote 'Steve, how frustrating is that! seeing a new and improved version of what we have been struggling with for the last 2 years

Yes, b****r - I knew this was coming after I spoke with TN last summer.  He's rounded-off the underfuselage and reduced the dihedral as well.  Might buy the set of mouldings when they go on sale separately, since the canopy looks better with accurate framing.  But thanks again for sending me the cowling!

BTW, all this talk about batteries and motors, what do you think about TN's setup in the new model, as described in the E-bay blurb?  I suspect it is the same as his B17 and he told me that had bags of thrust

Steve

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Re: Leccy Lanc XI
« Reply #73 on: February 27, 2006, 10:32:21 AM »
HI Smark
          I studied your thread post regarding the gear box conversions last night,(that was my insperation :af) and think you made a magnificent job of them. I wasn't going to go to the same lengths you went to as i don't have the necessary engineering tools to make a perfect job of it, and would probably end up destroying the boxes completely.
Also i think the reason your original shafts were bending is probably more due to the heavy I.C. type spinners you were using at that time. The spinners that come with the nexus design are very light weight vac formed plastic, and as such apply very little load to the shaft.But i am still going to nick a lot of your ideas though :)
I think the most important thing is, when cutting the castle section off the main gear it will need to be cut perfectly sq. As when the prop adapter is tightened on to the protruding shaft, it will probably pull tight against the hub of the cut down gear. If this cut is not perfectly sq. the adapter will pull the shaft off centre, and will result in a vibrating box.
The shafts are very thin i agree, but by keeping the gear tight against the gear box housing (allowing slight clearance to move) and the prop adapter tight against the gear hub, then it should produce a solid shaft with no weak spots to bend at. As i say the spinners are virtually weightless, its just the extra prop weight to worry about.
Like your ideas though, and its definitely given me a way to move forward out of this dead lock :af

Cheers Walts
« Last Edit: February 27, 2006, 10:47:54 AM by Walts »

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Re: Leccy Lanc XI
« Reply #74 on: February 27, 2006, 10:45:14 AM »
Hi Steve,
         Yep the power system doe's sound intriguing on his new design, trouble is the description doesn't tell you much, just sp400 6v motors on 16 cells. I'd like to know how that works.I initially thought he had redesigned the lanc to carry more weight, after seeing us struggle, when he states a new AUW of up to 61/2lb, but looking at it again the extra weight would appear to be all in the extra 8 cells its carrying, so the same basic airframe weight :(

Walts

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Re: Leccy Lanc XI
« Reply #75 on: February 27, 2006, 11:59:43 AM »
Hi guys, I think Tony is using a series/parallel setup, like mine - but using 6v motors ....

Jersey Lanc


Tony's Lanc


What this circuit does, is allow the overall power (W) to remain the same, but by doubling the voltage, you halve the current - which means the flight duration goes up  :af

regards
BD

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Re: Leccy Lanc XI
« Reply #76 on: February 27, 2006, 13:21:15 PM »
Cheers BD
           I can see what you mean now, but its purely for duration then and wont increase the power. No good to me then i thinks, as the extra cell weight will only worsen my power requirements.
Walts
« Last Edit: February 27, 2006, 13:31:58 PM by Walts »

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Re: Leccy Lanc XI
« Reply #77 on: February 27, 2006, 13:38:36 PM »
Hi Walts, yet another option for you  :D

How about a 3s1p Lipoly ?  You can get a 3300mAh cell now that is good for discharges of 20C continuous, which would be able to sustain a current of 60+ Amps ......

Best bit is that it only weighs 260g - down side is that it means slinging some cash at it, but for around 60 you'd lose some weight, up the supply voltage a tad - which given that you're already losing some on load, might well put the model up into the 50W/lb area .....

regards
BD

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Re: Leccy Lanc XI
« Reply #78 on: February 27, 2006, 13:46:22 PM »
BD
   You little devil you :ev I'm just about to spend some money on my gear box mods and you throw somthing else at me. food for thought though.

Why you are here i am about to order some props, I've seen some graupner 8x6 slim props, supposed to be ideal for 400 geared motors, and there black ;D do you think they will be as good as the APC's.

Cheers Walts   

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Re: Leccy Lanc XI
« Reply #79 on: February 27, 2006, 13:56:40 PM »
Nope! the mans gone I'am all alone again :'( :'( :'(

I really must get a life ::)
« Last Edit: February 27, 2006, 14:02:43 PM by Walts »


 

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