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The Building of the BebBit


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Well the Easter break is here and its the time I promised myself I'd make a start on the BebBit! So as proof here's a couple of piccies....
 
I'm starting with the fuselage, no fundemental reason, but I always start there! The fuse halves have been glued together and the doublers have been added, making sure of course I made a left and a right (hands up anyone who hasn't made that mistake at least once!) and here I an adding the longerons.
 

My building board, in case your interested, is a piece of Melamine sheet faced with a double layer of cork tiles. I've had this for a while now and it works well, straight, stable and takes pins well.
 
Next up the 1/2x1/8 bracing pieces...
 
 
I use aliphatic, so I have to wait while everything dries properly now!
I'm luckier than Dave in that I have a dedicated building space, and I'm luckier than some in that its not in the attic! But it is in the "box room" so its quite small. Here's an overview of my build area (excuse the mess!)
 

And here's the view looking the other way...
 

Doesn't look to bad eh? But to get that space these fellas (who normally live in there as well) have to be moved onto the landing!
 

This does not make me popular with those who want access to the bathroom!
I'm hoping to move into the garage later in the year when I'll have a lot more space - Mrs BEB has given consent, presumably she is fed up stepping over and around models in order to visit the loo!

BEB

Edited By Biggles' Elder Brother - Moderator on 21/04/2011 21:32:37

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Mmmm, as this is likely to be of the "stick one piece in place each day and eventually you'll have a model" sort of build I suspect a webcam would be a bit boring!
 
I don't plan to do this as a blow by blow account as the lead builders, and others like you guys, have already done that brilliantly! So just occassional updates as when it seems relavant.
 
BEB
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Hi Chris, yes me too - happy days in the ATC and all that! It is a lovely model to fly. You can just potter round very scale like, or if the urge takes you its quite good at aerobatics for a scale model.
 
Anyway, back to the WebBit. I wanted to go flying today, but the wind was just too gusty. So, after tripping down to the field and have a chat (but no flying!), I came back to play WebBits.
 
Fair bit done today, but not a lot to show for it . All the preparatory work ready to assemble the fuselage.
 
Personally I dislike wing bands, so now we have the first modification to Steve's design. I've added a wedge of 1/8th balsa to the windscreen profile so as to extend it above the centre line of the wing profile. This will allow me to use dowels in the leading edge and nylon screws in the trailing edge to hold the wing on.
 
The picture below shows the wedges being fitted...
 

The ply rectangle is going to be the dowel locating plate.
 
I've also extended the fuel tank shelf to make a battery tray for a 2200 3s and drilled the firewall for the motor mount and installed the captive nuts.
 

The picture shows the dowel locating plate in approximate position, above the fuselage side is the extended fuel tank shelf which will become the battery shelf. Top right is the firewall with captive nuts and a slot cut to aid cooling and provide a route for the wires from the motor to the ESC.
 
I have also built the servo shelf with cut outs for the servos, hardwood rails fitted and space to the Rx - so that's ready to go in.
 
With a bit of luck I'll have the fuselage together tomorrow.
 
BEB
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Posted by Big Bandit on 22/04/2011 15:49:49:
I have some full size hours in one from some years ago.
 
Cheers,
 
Chris.
 
Me too Chris, time in the Chipmunk, and Sedburgh Gliders and 3 solos in the T21.
Happy times.
 
Thinking about it was the T21 the Sedburgh (Side by side) and the solos done in the Kirby Cadet?

Edited By Chris Bott on 22/04/2011 22:38:46

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Hi Chris,
 
Just loved the power flying 1969 at RAF Newton, but I also did the gliding course at RAF Spitalgate, the Slingsby we nicknamed the Brick and the Sedbourgh a barge. Still do a bit at Husbands Bosworth.
 




Just love the Tug. Sorry BEB, just couldn't resist.
 
Chris.
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We're making progress - albeit rather slooooooowwww! Too much flying in the nice weather and not enough building!
 
But I have the fuselage together now...
 

As you can see we have an extra couple of formers! One in front of the wing to hold the wing dowels and one at the rear of the wing - just under where the trailing edge of the wing will fall - with two 4M captive nuts fitted to receive the nylon wing bolts. One slight issue with this is that I hadn't fully appreciated just how narrow the WebBit's fuselage is, the dowel and bolt holes are only 1" between centres - that doesn't offer a lot of resistance to twisting. I'll just have to hope its enough! I will probably reinforce the dowel holes with some tubing, that should help.
 
Here's an "overhead" view showing the wing bolts, battery tray and the servo/receiver installation...
 

The rx is not fixed in yet - hence why it looks a bit wonky! I was just trying stuff "for size" really. The ESC will go under the battery plate and there is a wide slot cut in the lower firewall to run the ESC/Motor wires through and to direct some cooling air at the ESC.
 
I'll sheet up the bottom and the rear upper fuselage next. I won't put the "windscreen" former and sheeting in until I've built the wing as it will be easier to alingn the wing locating dowel holes without it there. It will also make velcro lining the battery tray a bit simplier!
 
BEB
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Quick progress report. Managing to get a little bit done now and then. This afternoon was useful in that it got too windy at the field so I decided to come home and make a bit of progress here.
 

As you can see the rear part of the fuselage is now sheeted up and the wing is well underway. I've just got the capping strips to add on this side then I can turn it over and sheet the other side. I then have to think about how I am going to fit the aileron servos.
 
BEB
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Well the wind has grounded me, so progress on the WebBit improves . As I said at the begining I'm not doing a "blow by blow" blog as this has been done better elsewhere. I'm just going to deal with anything I do that is outside of the standard WebBit instructions.
 
I've decided I want to fit separate aileron servos in each wing rather than use the original single servo working a pair of torque rods in the design. The problem is that the WebBit's wing ribs are very thin and I'm not too happy that they can support the servo and control surface forces unaided. OK, if I'd thought on I would have made a couple of substitute thicker ribs - but its a bit late for that now!
 
The solution I've come up with is 1/8th balsa rib doublers on the ribs either side of the servo bay in the wing. So I made 4 of these:
 

They glue to the rib and the back end butts up to the false trailing edge and the front slots between the upper and lower spars. So this will impart a lot of additional stiffness and strength for relatively little extra weight.
 
Here are the doublers being installed either side of the third bay out from the centre on each side, installation is from the as yet unsheeted underneath ...
 

Next I need to build a hatch to support to servo tray and provide a boundary surface for the film. This is constructed from 1/4 sq medium balsa. Here are the top and bottom rails of the hatch being glued in...
 

A small slot is placed in the inter-spar webbing at the back of this bay, this will pass the servo lead which will then run along the D-box to the wing centre.
 
I now made two hatch covers which will double as servo trays. Made from 1/8 lite ply with a slot cut for the servo arm and two hardwood bearers added to act as servo mounts - just like the sort of thing you would see in any number of ARTF's...
 

Servos are fixed to the covers and the cables threaded through the D-box prior to sheeting it up. Also 1/8 ply corner pieces are added to the hatch way, these strengthen the hatch, act as a supporting ledge for the covers and screwing down points...
 

The hatch covers can then be dropped in place...
 

With the rest of the sheeting completed, the rib capping in place and the aileron servos installed the whole thing looks like this...
 

As you can see from the above I don't belong to the Chris Bott school of "build it light"! I could use Chris's cut out discs as extra strengthing pieces!
 
Well, just the trailing edge, ailerons and wing tips to do now and the wing is finished. Not much chance tomorrow - I have to be "a Dad" and take the family out!
 
BEB
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Looking good BEB. All that lack of build it light should mean you don't have to strengthen it afterwards like me. I so wish I could get out there and test mine again though.
 
No modelling here either I've been kept busy stripping our smallest room, including new floor and ceiling, sorting my daughters brakes and doing an awful lot of shrub cutting and shredding. There really is no peace...
Delivering daughter 2 back to uni tomorrow and that will be my bank hol.
 
I guess there's no rush to get yours covered, but then suddenly we might be met with some decent maiden weather?
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Nice job BEB,
 
The servo mounting reminds me of the type of mounting on the Eflight Taylorcraft, very effective. Far too gusty down here today so it's back in the shed, try to finish the Webbittneezzer for the Mayfly meeting at Old Warden next weekend.
 
Cheers,
 
Chris.
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OK another little departure from the standard WebBit script.
 
As I said earlier I'm not a big fan of wing bands so I'm modifying the BebBit to have bolt-on wings. As such the mod itself is very straightforward, just a couple of extra formers - one with two 4mm captive nuts fitted, two dowels in the leading edge and two bolt holes in the trailing edge, but there is one little problem - the WebBit has a very narrow fuselage for the size of its wing. This means the dowels and the fixing bolts are narrowly spaced and don't offer much resistance to axial twist. Which in turn means I will have to bolt the wings on pretty tight. Now the problem with that is the bolt holes are in the balsa trailing edge - if I start regularly tightening up the bolts I will gradually crush the balsa
 
Solution - I need to let a ply plate into the trailing edge.
 
First step mark where the rebate for the plate is going to be...
 

I'm going to use 1/8th ply, so obviously the rebate will have to be 1/8th deep. To start I took my balsa stripper and set the scalpel blade so that it was 3/16th below the plate of the stripper. With this I then cut round the perimeter of the rebate.
 
Next I reset my balsa stripper blade so that it was 1/8th below the plate and scored a series of horizontal and vertical cuts inside the boundary of the rebate...
 

All you have to do now is take a scalpel and use the point to "flick" the little squares out. The balsa wont split outside the boundary because the cuts between the squares are 1/8th and those around the boundary are slightly deeper at 3/16. Clever eh?
 
So, your left with a pretty neat 1/8 deep rebate. Any remaining bits here and there can be trimmed out with a sharp scalpel blade....
 

As you can see we have the ply plate ready. Just glue it in and drill the holes through from the back and hey presto instant reinforcing...
 

So, with the wing on - from the back....
 

And from the front....
 

Since these photos were taken earlier today I have added the wing tips. So just finish fitting the lower sheeting and a light rub down and she's ready for the basic covering. Still haven't decided on the colour, I'll have to have a rumage among the old ends of film and see what I have enough of - it'll probably be white and something...
 
BEB
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  • 2 weeks later...
Last night I had a little time so I made up the undercart - I was very careful to make it just the size on the plan, but I think the trailing arm is too long. As it is it positions the undercart much to far forward at an extreme angle? Looks like I'm going to have to desolder it, trim the trailing arm and reassemble
 
Anyone else had this problem?
 
BEB
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