Zulu ET

[Joe Hull]

Lindsay, can you tell me where you got your tail wheel assy. Did you get it in the UK?

 

It looks particularly strong with metal bracket extending along the rear fuz etc and I like the coiled spring part for some cushioning on landing.

 

I have scoured the internet for a similar one. Found one on USA site which looks similar but postage could be quite high I would rather get it from UK supplier if poss.

 

My Zulu ET build is coming along. I have finished the wing and have to do the D box on top of fuz yet and then start covering I guess.

 

Also what sort of filler do you use?

 

Is ordinary Polyfilla OK or do you use someting more sophisicated for models?

 

I am quite new to all this really.

 

Joe

[Lindsay Todd]

Hi Joe, it is from The World Models 60" Cub, should be available from Steve Webb Models. I am sure there are others also, I tend to go round the model boot sales and pick all these bits and pieces up, its amazing how much you can get for  a few quid.

 

cheers

 

Lindsay

[Jimbo565]

Joe,

 

I use Wilkinsons All purpose interior filler,mix it with water to a creamy paste and away you go.

It dries white and is very easy to sand,some of the ready mixed fillers are hard to sand.

 

JIm

[ian ludwell]

Well here we are again,well into the wing build,have glued the centre wing brace to one wing and clamped the other just to sit it on the fuz,not sure whether it is sitting square,the top of the former looks as if it may have warped slightly after fitting or after being cut,will have to check this when wings finished,nice idea with the filler Jim,i was a bit curious what to use,bye for now.

[Lindsay Todd]

Jim, I use exactly the same stuff, if i'm applying it two compound curves, say a wing fillet or very thin, I add a lttle pva glue as helps bond but reduces the ability to sand easily. I also have a tub of pollifilla fine, but only use this on sheeted surfaces to fill glue joint gaps prior to a coat of sealant such as cellulose dope, sanding sealer, epoxy or acrylic varnish pending final finish.

[Joe Hull]

Thanks for the advice Lindsay and Jim very helpful to have this info

 

Joe

[Joe Hull]

I am almost at the stage of putting the covering on.

 

Lindsay, why is it necessary to use a sealant on the wood, is it because the film covering will not stick to bare wood if you do not seal the surface?

 

I am using 'Oracover' which is the same as 'Profilm' I believe, a polyester material.

 

Some RC experts on the internet say that presealing sometimes melts and makes a mess under the film if you put heat or when ironing on the film, is it important what sealant to use?

 

This is the 1st time I have done this so I want to get it right.

 

Would appreciate any advice please.

 

Joe

 

[Lindsay Todd]

Joe, you do not need to seal the timber if covering with films, I think you have got a little confused by my earlier mail witch was more general to various types of covering techniques such doped nylon or epoxy laminate. Not to worry cover straight onto the wood although if you are fitting an i/c engine fuel proofer is a good idea to the engine bulkhead and tank bay, if its electric as per the original you don't need to bother.

 

Lindsay

[Joe Hull]

Oh good that's a relief, thanks for confirming this Lindsay much appreciated.

 

Joe

[Joe Hull]

Lindsay/ Kit

 

what is the current consensus on motor size prop combo for Zulu ET.

 

I bought a BC 2836/9 motor with 40 amp ESC very cheap from 'RC Timer' as Kit had done the same.

 

RC Timer recommend 12x6/9x6 prop

 

To confirm this I used a program on a model aircraft web site to check how a 9X6 would perform with this 243 watt motor.

 

It comes out with highish efficiencies (about 70%) a current draw of  about 24 amps on full power and a static thrust of 15.6 oz or 443 grams and a model speed of 43mph in level flight.

 

Not sure how it works this out, because no where do you enter the model weight! - only the weight of battery, motor, ESC + 10%

 

The program confirms static thrust/ power weight system OK

 

Would appreciate any advice please.

 

Joe

Edited By Joe Hull on 14/12/2010 12:37:31

[Kit Davidson]

Yo Joe! 

I cannot give advice, only the results of my experience so far. This is what I know about propellers. Relatively:

 1. Propellers accelerate a large mass of air to a slow velocity.

2. Gas turbines accelerate a small mass of air to a great velocity.

For a given power setting: 

3.  The greater the propeller diameter, the greater the mass of air accelerated.

4. The greater the pitch of the propeller, the greater the distance advanced.

5. Smaller pitch propellers accelerate the aircraft quickly to a limited top velocity.

6. Larger pitch propellers accelerate the aircraft more slowly to a higher top velocity.

 

I am following Lindsay's design recommendation because as a newly qualified pilot with the reactions of a striking tortoise, I had my fingers burnt when I fitted an 11 by 7 propeller to the motor you have now also bought. I have tried twice since then to successfully test fly my Zulu but for reasons too embarrassing to mention, I kept nosing over on take-off and damaging propellers on the asphalt. Nothing daunted I cropped the propeller with scissors and tried again. By now I was suffering from frontal masking as described in my posting of 23 November. With reduced propeller diameter and power my Zulu hardly lifted off the deck and stuffed in on its nose. My wing retaining bolt sheared as designed but the torque transmitted to the wing half- section atop the windscreen broke frame 3 at its thinnest points just below the wing. The repairs are easy but I will have to get a new wing retaining bolt from somewhere before I can fly again. I am so new at this game I do not have enough spares at hand yet.

 

Other problems I suffer are connected with the battery tray. It has broken free in relatively minor nose-overs and decelerations several times. It cannot restrain the mass of the 3 cell lipo. Similarly the motor has ripped itself away from 1 bulkhead twice as the propeller grounds. I plan to make my battery tray access hatch much bigger so that I can reinforce both areas.

 

 

[Bryan Ward]

Kit

I would guess i am same as you, but have some helpfull mates and the first thing they said was it would nose over and it helped to bend the u/c foreward, but i am busy to move the u/c foreward to match the leading edge. Other than that it flies like a dream and i anticipate a lot of fun with it.. As i mentioned before i live in South Africa so  can fly most weeks. At the moment am busy organising a floating pontoon for the club members that have float planes. if you would like to look at our site go to www.vrcmc.co.za Hope info re U/C helps you

Bryan

[Kit Davidson]

Nice one Bryan. I forgot to mention in my massive missive that I took and accepted the same advice. The ZULU attracted a lot of interest and admiration but the undercarriage business was an unanimous opinion. My undercarriage is now bent well forwards like yours.

 

The UK tour is over and the World Champions returned battered, bruised and under a substance abuse cloud. What price the Springboks now? I think Jan de Villiers needs a bit of bending too. 

[Bryan Ward]

Kit

The design calla fot u/c to be just forward of stn 3. I have removed my u/v and in the South African vernacular bent it straight, put in a new mounting block just aft of stn 2 moving the u/c 48mm futher forward. If it stop raining tomorrow  (its a Public holiday here) then i will try it out and let u know

Bryan

[Joe Hull]

Hello Kit,

 

I would not be tempted just to cut the end off the propeller. I would have thought that this will affect the air flow at the tips of the prop blade and drastically change the aerodynamics and efficiency of the prop.

 

Props are quite cheap to change really. I have done a lot of homework on this subject recently and there are various programs on the internet to match props with different motors, to at least guide you to a correct size of prop for a particular chosen motor.

 

As well as power, the Kv is important. I found this out to my cost. I bought a S/H Seagull Innovator trainer off a club member with a Tornado 540 watt 1250 Kv motor and flew this few times in training with an instructor but it burnt out 3 ESC's (40amps) using  a 11x7 and then a10x6 prop.

 

It was then that my instructor did some tests with a wattmeter. The result wa that it was drawing over 50amps. We realised then that the correct prop for this motor and a 40amp ESC is no more than a 9x6 and I am tempted to put a smaller 8x5 on it.

 

I will be trying a RC Timer 40 amp ESC with RC Timer 243 watt with 880 Kv motor  .

 

With this combination I think we should be trying a 9x6, 9x5 or 8X5 prop. It will be interesting to see how Zulu ET performs with this set up.

 

I have just bought a sealing Iron and hope to start covering in New Year when the weather warms up a bit.

 

Snowed in here in West Somerset!!

 

Have a Happy Christmas and New Year

Joe

[ian ludwell]

Just a few words as to where i am with  motor/esc/ prop and li-po.

i have a  xyh 3536 1000 Kv brushless outrunner coupled to a 33A esc powered by a 3s 2200 mah 11.1 V li-po turning an 11x5.5 apc prop.

This from my Wattmeter equates to 205 watts at 21 Amps,so hopefully at the weight of the model there should be enough power.

I have other electric models that i have coupled to the wattmeter and doing this has enabled me to make a better judgement on which combination to choose.

i also have a battery tester which gives-total voltage, individual cell voltage,% battery capacity total and individual cell capacity,it also shows the difference in volts between the highest and lowest cells,.

This has shown where one of my li-pos had a faulty cell,2 cells were at 90% capacity and the other cell was falling from 90% to 45% within a few hours,so this one has to go unless any one thinks it can be converted safely to 2 cell 7.4 v,Wishing everone a merry

 christmas and a happy new year,sorry for the lenght of this post.

 

[Mike Robey]

Hi Lindsy,

 

I have started in on my Zulu ET.  Very much enjoying the build and thank you so much for

the materials list and "how to" posts that you put up on this on this forum. They have helped me so much, especially with the fuselage.

 

My question is this.  When marking and cutting the parts I often scan in the plan of the part concerned, print it out, glue it to the material.  I then cut it out and peel away the paper.

 

In the past there are no issues with this because all of the plans I have done this with have been downloaded free from the internet.  My question is if I do that with your plans am I violating copyright?  So far I have been using tracing paper but its painful compared to the above technique.

 

Don't want to tread on any toes or break any laws which is why I ask.

[Jimbo565]

Michael,

 

You sure are giving yourself a lot of work there, I've been at it for forty odd years and by far the easiest way to do it, use carbon paper,trace the parts from the plan onto thin card and cut them out and you now have a template to mark round on to the wood

The templates can be kept for safe keeping and can be of use just in case another part has to be made in the future.

 

Jim 

[ian ludwell]

Hello Michael,as Jim mentioned,carbon paper is a good idea,if you don't have any carbon paper to hand the stationers  "RYMANS" sell it in packs of 10 A4 size sheets and not too pricey.in Blue or Black.

[Mike Robey]

Hi Guys,

 

Thanks for the info on the carbon paper.  I will use that if i can't scan/print/cut.

 

I know it sounds a bit fiddly but it is actually really easy and convenient.  The only two tricks are making sure your printer is printing at 100% and peeling the paper off as soon as you have finished cutting (comes off easy then but if you leave it for a while its like scraping wallpaper).

 

However Carbon paper sounds like a lot less mucking about than tracing paper so if I can't scan I am definitely going to try that. This build is like a time machine for me. I am rediscovering many things from the days before computers and power tools.  Through the need cut the lite ply formers I rediscovered coping saws and hand drills (yes the ones you turn the handle on not the ones you put the batteries in) and now carbon paper.

 

[Lindsay Todd]

Guy's firstly Merry Christmas to you all, copyright as my understanding is relating to selling or publishing to third parties so no issues as I can see so don't think about such stuff and enjoy the build by whatever method you choose. My web build Zulu ET has now been skiing witch was fun, I will post some video after christmas when I'm aloud to play with my new toys.

 

Lindsay

 

[Mike Robey]

Posted by Lindsay Todd on 23/12/2010 10:33:11:

Guy's firstly Merry Christmas to you all, copyright as my understanding is relating to selling or publishing to third parties so no issues as I can see so don't think about such stuff and enjoy the build by whatever method you choose. My web build Zulu ET has now been skiing witch was fun, I will post some video after christmas when I'm aloud to play with my new toys.

 

Lindsay

 

Thanks Lindsay.  Look forward to seeing the video. Summer in Perth but the wind hasn't stopped howling for almost 3 weeks (sigh...). Below is a picture of my progress so far.

 

Merry Christmas to one and all.

 

 

[Lindsay Todd]

I think she looks pretty cool on her skis, hope to get a fair bit of flying in over the next week.
Lindsay

 

[Jimbo565]

That looks magic Lyns my  man.You must have better weather in your neck of the woods than we have in the North East

 

Stay cool

 

Jim 

[Marcel Wey]

Hi everybody,

My dad builded the Zulu ET for me, and i've finished the artwork, so i wanted to share this with you all!
The plane is ready to fly, can't wait to get it airborne!
Here are the results:

I love this plane
Thanks to Lindsay for the plan and thanks to my dad for building it

Happy holydays!

Marcel Wey

Edited By Marcel Wey on 24/12/2010 20:51:27