The Big Ship - first build help

[Geoff Bradley]

I'm presently sorting out the power train and was intending to use a 10" prop. but am not sure about the pitch.

Having looked through the build article several times I can't find any reference to the size of prop you used with your SC30. As it flew so well it makes sense to use the same so I would be very gratefull for any advise you can give.

 

[Peter Miller]

I used a 9X6 propeller on the SC 30 FS.

 

However the props used on i.c. engines are not the same as used for electric power and you should use the size suggested for your power unit. You see it depends on the r.p.m of the motor etc.

 

I am sure someone will suggest the best prop if you tell the the motor and size and  weight of the model. When it comes to electric I haven't got a clue.

[Geoff Bradley]

This electrickery is very complicated for a newbie like myself partly because everyone seems to have a different approach.

Since my last posting I've found an article in the special RCME by Tim Mackey. He says there are a number of ways to approach planning the power train and one method is to start with the prop.

At the begining of this thread he gave me power train advice so I think I'll do a lot of investigation, mathmatics and head scratching then ask him to help with any dificulties I encounter.

 

Thats the next six months sorted then !!!!!!!!!!!!!

[Bruce Richards]

The problem with Electric power is that there are so many variables. So the way to simplify is to make some fixed (not really fixed but just a stake in the ground) decisions to start with. As Tim says start with a decision on what sort of prop size you want and work from there. Another option is to start with the battery and work towards the prop.

 

If while you are doing your calculation it is just not working out, say the current is just too high, then try and start from a different fixed point. 

[Peter Miller]

Now you know why I stick to i.c power.

 

Electric power was basically simple when you had Speed 600 motors and 6 or 7 cell nicads. Even then you had to worry about the prop etc.

 

Engines are so nice and simple. A given range of props for any size, any one of which will fly a model of a suitable size for that engine. Put fuel in the tank, start the engine and fly.

 

I watch the electric people with their chargers and batteries and balancers and analysers. And then I hear "Is the speed controller playing up,? Has my Lipo had it? Oh I discharged the lipo too far now it won't charge. AND SO IT GOES ON!!!

 

 And guess who gets asked to add a car battery to their trolley to lug the thing from the car to the pits?

[Geoff Bradley]

I understand both sides of the arguement and have no preference for either power option.

I just find it all very interesting and enjoy the challenges that are thrown up with electrickery -  mainly because I understand mechanics but electricity has always been a mystery to me.

Peter - I'll make sure that I lug my own car battery to the pits!

[derek critcher 2]

Hi Peter I have just finished building my big ship and am ready to cover. I would be interested to hear of your covering sequence to cope with some of the awkward  angles

and compound curves at the front end, and also the change of colour over the wings.

thanks Derek Critcher.  

[Peter Miller]

WOW! That doessn't need a post, it needs an article!

 

OK, I will try to compress it. Cover the underside first. and wrok upwards on the fuselage.

 

The secret of covering compound curves is to iron the covering material down on the flat and then stretch the material and heat it as you pull it down onto the wood. It takes practice but you soon learn the technique.

 

To do the colour change on the wing just cover the whole wing in the base colour. Then iron the trim onwith a cooler iron to prevent it from creeping. Iron it down round the edges but leaving one section open. Use a heat gun to shrink it from the points furthest from the open section and rub it down with a cloth as you heat it. Prick bubbles with a pin and iron down.

 

You coculd also iron the bas colour down from the front spar back and then iron the trim colour down to the main spar and leading edge and shrick. be careful not to pull the coving away from where it is stiuck down

 

Use Solarfilm Supershrink Polyester. THis material is much better and you won't burn a hole through it.

 

Hey, I just made 2000 posts

[kc]

One thing Peter did not say is that you should keep plenty of excess 'film to grip in your hands when covering wingtips etc.  The extra length allows the curve to form somehow. 

 

Also Prymol etch primer helps to allow the overlaps to get good adhesion.

[derek critcher 2]

Hi Peter, I,m just putting the finishing touches to my "big ship" and having treated myself

to a nice little ASP30 four stroke to complete the ensemble, I,m interested to to hear

what you used to extend the exhaust, the pic in the RCME appears to show a length of copper, if so what did you use to fasten it to the silencer tail-pipe.

I,m delighted with the look of B-S and hope the weather stays soft enough to get a flight

in befor the end of the year, if not I,ll just have to go back to the workshop and make a start on Van's RV3, cheers, Derek. 

[Peter Miller]

I used brass tube. I filled it with molton lead and allowed it too cool. YOU DO THIS AT YOUR OWN RISK! I fed the lead in while heating the tube with a gas torch.

 

I then bent the tube and melted the lead out again.

 

It is held to the end of the silencer with three tine self tapping screws, You could also add some epoxy but the heat softens this.

 

 

[Peter Miller]

I have discovered a silly error of judgement on the Big Ship. It can easily be corrected.

 

The plan shows a wire " on the undercarriage running under the fuselage. This is where the elastic bands attach that provide the backwards sprining of the undercarriage. This is shown as 16 SWG.

 

I kept wondering why my undercarriage sagged so much. I have just realised that the 16SWG wire can  twist far too easily allowing the U/C to move far more that it should do. In effect a very weak torsion bar.

 

The answer is to remove the V and make a new one of thicker wire. I made my new one from 8SWG wire but I think 12 or 10 SWG would probable do as well.

[derek critcher 2]

Thankyou Peter, it's back to the work-bench before I've even managed to fly my B/S

incidentally I have just finished rebuilding an Arising Star which decided to make an

unscheduled and spectacular landing without my help, I have converted it to tail-dragger configuration and also incorporated your sprung under-carriage as on the big ship, I see no reason why it shouldn't work O/K, what do you think? D.C.

[Peter Miller]

The model flies OK as is. I flew mine for two years in that state but the thicker V does make things much better.

 

All trainers should be tail draggers unless flying off concrete. The B/S type U/C should work well on the Arising Star.

 

Have fun

[Peter Miller]

I have now re engined my Big Ship with an O.S 35FP and it is much better. copes with wind, takes off with more authority. will even do rudder/elevator rolls.

 

Much more like my original Little Ship with an OS 10 FSR!!!

[Geoff Bradley]

Belive it or not I've finally finished the Big Ship and am getting ready for the maiden flight.

I'm confused by the instructions in the mag. that say to set the throw on the elevator to 1 1/4" each way - the elevator is only 1 1/8" long so I can't see how it can be achieved

Is it a miss print? I wondered if the rudder should be 1 1/4" and the elevator 1"

[Peter Miller]

Almost certainly 1/4" each way. and certainly not 1 1/14"

It is a long time since I built it.

[Geoff Bradley]

Thanks for the quick reply Peter

- fingers crossed that the weather holds up for tomorrows maiden flight

[Peter Miller]

Let us know how it goes, should be no problem at all.

[Geoff Bradley]

Well here she is ready to fly - the weather is holding us back. Fingers crossed that Wednesday is sunny !!!!

[kc]

It's possible to misread Peters comments on the throws......presumably he only means elevator 1/4 because I would expect the rudder to need a bit more than that.

Better to clarify this BEFORE the first flight!

[Geoff Bradley]

Thanks for that KC . I've got the rudder set to 1" as per the instructions in RCME so it should be OK.

[Peter Miller]

Yes, rudder at 1" is plenty.

Looking forward to hearing how you get on.

[Geoff Bradley]

Brilliant maiden flight.

Despite quite blustery winds the Big Ship coped well. My trainer was more than impressed with both model and builder. He thinks it is slightly tail heavy (easily sorted) and said we should consider a little packing under the rear of the tail!!! The leccy conversion works well - started with a 12 X 8 prop which drew 356W on full power ( for safety!) and ended up with a 10 X 6 wooden job that looks the part and gave plenty of power only drawing 208W max. It almost flies itself which with my flying skills is probably a good job !!!

An enormous big thank you to Mr Miller for both plans and help during the build - now what should I build next???????

[Concorde Speedbird]

Well done! The plane looks great!

How about a sports model next? You could go for a Wot 4, Acro Wot (in their kit forms, not the ARTFs), or the SLEC Funfly and there are many more! I have the Funfly, with a built up wing it is a fun build and it flies beautifully, here's a pic.

She's had 4 flights, she is very easy to take off and easy to land, and is a dream for all the bits inbetween!

I'm sure other people will suggest lots of other great models as well. Keep up the building and flying!

CS