Hip Pocket Builders' Forum

Radio Control Forum => Electrics => Topic started by: Hepcat on September 28, 2018, 08:51:42 AM

Title: Sunbird V2.0
Post by: Hepcat on September 28, 2018, 08:51:42 AM
As the years pass by I have no difficulty at all in becoming a stupid old man. A few weeks ago I had the idea of buying some RC gear (a branch of the hobby of which I have no knowledge or experience). At about £35 it seemed a lot of money to me but my daughter said :’Dad, for goodness sake stop dithering, it costs more than that to top up my petrol tank each week.’ So I ordered it. I intended to design a glider with an electric motor in the nose so it could climb to something like towline height and then I could guide it down with the RC to somewhere near my wheelchair. At this point a bit of common sense penetrated my thoughts.  I had not the slightest idea what I was talking about. I did not know what radio and electric stuff looked like or what it weighed so it would be impossible to design a glider without more information. Instead of gathering information I took another blindfolded leap into big business. The company that were selling me the R/C were advertising a Laser cut kit for a glider with an electric motor so I ordered it.  If you want to check it is called ‘Sunbird’ V2.0 and the ‘Bang Good’ web site illustrates it in reasonable detail. It has a span of 1600mm, that is about 63 inches in proper units.
Now is confession time; I’m telling you all this because I am going to need lots of help before this crazy choice gets air under its wings. Here are the first three. The instruction sheet says use Super Glue, I intend to use PVA as better on wood. There is no mention of how to hinge the rudder, elevators and ailerons.  There is nothing supplied that looks like a hinge. A little bag has 10 pieces of plastics material, 1” long x 0.75” wide by 0.036” thick. They are ‘springy’ and will bend  quite a way if enough load is applied.  Could it be that these are intended to be glued into slots in the front edges of the control surfaces?
Last question for now. No covering material is supplied. Is this a case for ‘Mylar’ and tissue or are there better alternatives for a model of this size?

Title: Re: Sunbird V2.0
Post by: tctele on September 30, 2018, 04:05:12 AM
Hi John

To answer your questions. PVA glue yes much better but cyano for carbon to wood. The hinges are normally fitted into slots made in both surfaces, glue with a touch of cyano. Most on gliders of this size simply put tape on one surface after covering. Good old sellotape will suffice I'd suggest a full span piece on the elevator and rudder, perhaps a couple of securing squares on the opposite surface. Just sand a bevel on one surface so you get the required control "throw" needed. Re covering material, yes you could do tissue over mylar but I would suggest a lightweight film covering as they are much more puncture resistance, I tend to use Oracover/Profilm light, it is quite expensive though. A cheaper option for a slight weight penalty is their Easy Cover range, much cheaper and very easy to apply (No pun intended!)

Can I suggest a quick trawl on RCGroups in the "Sailplanes" forum will give you lots of options and ideas.


Title: Re: Sunbird V2.0
Post by: Hepcat on September 30, 2018, 10:52:06 AM
Thanks Tony,
That answers my initial worries very clearly. This is all very strange to me because since about 1940 I have only built things to my own designs and nothing from kits.  There are no proper plans or notes.  For some reason there is a full size, single line outline of the fuselage side view - no detail or notes.  Apparently one is expected to figure out how everything is put together from the laser cut pieces. A new selling feature is the revised hatch cover which is held in place with a magnet. The magnet is there in a little plastics bag but I suspect the old laser cut bits have been included because the 'new' hatch does not fit the fuselage.


Title: Re: Sunbird V2.0
Post by: Konrad on September 30, 2018, 12:17:35 PM
This is a bit of an advanced ship for a raw beginner in R/C.

I’d like to ask what is your experience with R/C and what radio do you have.
I ask about the radio as the weight of the servos becomes an issue at this size as does the need for some mixing to help with the landing.

Let’s not forget this site (HIP) has a section where many of your questions are addressed.
Here is a thread I did on a model much like your Sunbird. While it is not a step by sept review. I think you might find something of interest in the covering details.

I don’t know the cost structure of your area (Taxes and the like) but these iron on covering, more often than not, are less expensive than the traditional covering with Esaki tissue and dope.

I’m sorry to say that many of the products from Solar Film are no longer available as Solar Film ceased operation earlier this year. I like a product called Oracover-lite for this kind of structure. It does not need an adhesive added to the balsa structure. If you glass the fuselage an adhesive coating might be helpful but again often not needed.

I like HyperFlight as Neil Stainton knows his stuff and is real helpful.

Those little pieces of plastic are known as CA hinges. They work great for hinging of this type of structure. I hope they are a bit more that plastic bits. They should have a light fiber material on ether side of the plastic. This fiber helps the CA glue (AKA Super Glue) wick into the structure and make a good bond.

John can you post photos to this forum? With builds like this photos might help us help you, as we might see problems developing that you might not know to ask about.

All the best,

Title: Re: Sunbird V2.0
Post by: cvasecuk on September 30, 2018, 01:47:05 PM
e-mail with build instructions sent.

Title: Re: Sunbird V2.0
Post by: OZPAF on September 30, 2018, 09:50:57 PM
It's good to see that you are being adventurous John. I have used the tape hinges that TCTELE mentions and in fact am using them on a 2900mm electric glider at the moment. light, simple and they seal the surface gap.

The other plastic CA hinges are also good.

I'm not sure but it appears that this glider has ailerons with provision for wing mounted servos. If this is the case then I would suggest just adding more polyhedral to the tip section - to somewhere around 11-13deg(each tip) above the centre dihedral. I wouldn't worry about heavy braces - a extra rib and butt joint should be enough.

Going this way would avoid problems with mixing in the transmitter as Konrad mentions and would be a bit lighter, and I think you would enjoy it more.

I would also build it with PVA - although I know with the tight laser cut joints CA works fine but still needs controlled application.

I'm also a fan of Hyperflight John and think that Neil Stanton would be happy to give advice.

Yes please if you can put up some photos so we can help further.

Good luck.


Title: Re: Sunbird V2.0
Post by: Hepcat on October 31, 2018, 06:41:19 PM
I wrote a proper reply and then the program would not accept an attachment Now I think the attachment has worked  but I have lost the reply.  I will leave things for now just to keep in touch. I twas mainly saying that mounting the motor did not look simple to attachand I just can't imagine how the propeller fits on.

Title: Re: Sunbird V2.0
Post by: OZPAF on October 31, 2018, 07:39:49 PM
I was puzzled a well as the supplied cross mounting plate is not actually needed. one of the photos on the Banggood website shows the motor installed to the back of the firewall and also indicates that you need to buy a folding prop set which was not included.

The hub of the folding prop would have a collet to grip the shaft on tightening the prop nut.

The folding prop blades are here

The spinner prop hub assembly is here

You will also need a speed controller - ESC (electronic speed control) as this is also not included but they have a link to the recommended selection in the table at the bottom of the first link.

I hope that helps John. It's not all that obvious until you have actually solved the problem before.

One thing to watch with the motor installation is to keep the power wiring way from the rotating back of the motor. Careful routing of the cables should be enough.