Topic: Big Stiks

Thought I'd start a bit of a blog on this in case any of you are interested.

A group of friends (6 of us) are building Ugly Stiks from an enlarged and adapted Phil Kraft plan. We have enlarged them to 81.5" wingspan. There are some variations within the build on individual models but the airframes are identical in construction.

They are being powered by 28cc Homelite leaf blower engines which have been removed from Ryobi leaf blowers and modified to raise the rpm.

Engine modifications are still ongoing but we are currently at 7350rpm on a 16x8 prop.

Templates have been made for most of the major parts and this has really helped to make construction easier. After all, there were a total of 144 wing ribs to make- you wouldn't want to do every single one by hand!

Here's a couple of photos to get started with.

I've cut out my wing ribs and Jim is trimming them to the template on his bench router spinning thingy. It does an ace job of saving time.



I later cut the details on a jig that had been made for the job and then put them to one side awaiting wing building time



I was a bit behind as I hadn't got my wood order in at the same time as everyone else, so I'm busily making the formers (1/4 balsa made from cross grain laminations of 1/8)And sneakily taking the occasional shot whilst Jim trims down the 1/16 ply doublers on his fus sides



A jig and a bit of glue later and two of the fus's are built up:




Next day (today) I managed to get home for my meal break and got an uninterupted hour in the garage which resulted in my fus sides being built up and the ply doubler glued in place. The fus sides are a shade under 57" long at this point.




I've heard that the Stik won't knife edge, so I've enlarged the rudder on mine by 40mm to try and cure that problem.



That's all for now, but there's always progress on someone's Stik each time I visit Jim's workshop, so I'll post more updates as and when they happen.

The end result should be six nice Stiks without having spent a fortune on them. If the engines don't turn out to be powerful enough we'll most likely go for Gf40's instead and save these for something smaller with a very short nose.

There is a question I need to ask, though.

The original Stik had banded-on wings and needless to say these are going to need something a bit more secure.

Would bolts front and rear or dowels and bolts be preferable?

Can anyone show me a good example of the construction of the wing in this area to give me some ideas? I'd thought of making a couple of ply sub-ribs that just sit inside the fus and then making a boxed structure within them to hold a pair of 13mm hardwood dowels into F2, but am also open to other ideas.

Quick question. I built my wing without the plan and it was discovered that we had cut too many wing ribs. I spaced as per the plan but have ended up with a 91" span instead of 81.5", an increase of 12%.

Other than slowing the roll rate a little bit can anyone see a problem with this? The wing is sheeted and boxed with 1/8th balsa so is a strong a as a very strong thing.

Given a guesstimated AUW of 10lbs that would give me a wing loading 15.84oz/ft² and with an AUW of 12lbs 19oz/ft².

Is that too light and floaty?

Just wondering how the builds are going ? and how have you decided to hold the wings on ?

A couple of them are ready for covering. Mine is still in progress (I'm doing the D box on the wing-  fus, stab and rudder/fin are built).

 A couple of guys have dropped out for various reasons. They may return/catch up.
each to his own with the wing security, but in my case I'm using ply box section glued to the ribs/spars holding 13mm hardwood dowel. Trailing edge is to be bolted down.

Oh, and I've increased the size of the control surfaces just in case I ever get good enough to take advantage of them! 

Ooops Sorry ment to ask are you doing the wing as a one piece or are you putting a joiner in to help with transport ?
Very interested in your project , just might have to have a go!

Ah, got ya.

The wing is one piece. I have a Mitsubishi Delica that can swallow a wing that size and still have passengers!

I use a pair of roof bars fitted inside and upside down (and heavily padded) to put the wings in at roof height, leaving the back seats for the fus.

Here's a couple of pics taken before I started doing the D box on the wing:

Mini update.

Have finished sheeting the wing and am now sanding it smooth(ish) and filling with ultra-light wood filler.

Have also fitted the engine so I can finish the back of the firewall and not unintentionally mask off mounting holes with quadrant. Have fitted some cut down penny washers at the back to spread the load. Fus is pretty much finished otherwise, and is ready for covering once I've fuel proofed the front end. Problem is that my Volvo undercarriage turned out to be too short (although it will be perfectly good for something a little bit smaller) and so I either need to source three feet of 5mm aluminium or look at fiberglass or carbon fibre.

We had discussed making some out of fiberglass and made a jig and a prototype, but need to cost this out.

Here it is on the bench. Prop is a 23x10 Xoar.



And here's my ugly mug with the wing, to give scale to it all. There's another 7" of wing tips to add yet, but I'll do them last as they're bound to get knocked off. I don't have a lot of room in there.

I did one of these a few years back with a Piped MVVs35cc petrol.
Hope you are going to fit the split control surfaces on the wings. It was great putting full crow on.I had around 75* of movement on them if I remember. It would just about stop it dead in the air.Landing speed was nearly backwards.I mixed it with the throttle so it decreased as you opened the tap.  Great fun. Hope it goes well .

Simon

Hello Guys,
I was wondering why you are not using litening holes on the fuselage.  Big Sticks for years have used them to get about 15% of load off the fuselage.  Be careful if you use them.  Study drawings with them.  Attention at the rear taper at the tail feathers...I would not think about them as your specific Big Stick has a nice structure already in the last 12" of tail area.  I mean no need back there for litening holes.
Take care and I will be watching as I am building one this fall.
Albert

I don't want it any lighter!

I've just weighed it and the fus weighs 6lb with the JC51 and a 23x10 wooden prop plus the fuel tank in place. 3lb of that is the engine.

With the 91" wingspan I need a bit of weight to give me a decent wing loading. With the constant wind  coming off the ocean here you really don't want anything light and floaty. If this weighs 12lb finished it'll only have a 16oz wing loading.

The best handling plane I've ever flown was my 82" Eurobat, which had a 29oz wing loading!   

Hello BBQ,
Let me see you want it heavy.  O.K.  , but you can trade dead weight here for structural weight somewhere else.  That is the game I like to play.  Litening holes liten but I see your point.  How are you covering?  Are you using a shrink type cover?
Enjoy,
Albert

Currently debating between Solartex and nylon and dope.

The airframe is very strong already. The formers are laminated cross grain balsa, 1/4" thick and very strong. They've been bonded with CA too, which stiffens them up immensely. The fus is made from 1/4" and 3/16" balsa, with long 1/16" ply doublers. There is a 1/4" ply undercarriage plate underneath F2 and a ply firewall.

The wing is made with 1/8th balsa almost throughout and has been Dboxed to produce a very strong unit. It currently weighs 2lbs. It still needs the ply wing mounts, control surfaces, wing tips & servo boxes added. I expect it to weigh just over 3lb once it's finished.

Where would you suggest I add the extra strength?

You seem to think I want it heavy, but what weight do you consider heavy for a 91" span sports model? The 50cc ARTF Edge/Sukhoi/Extra/Giles/whatever generally come out around 15-18lbs with an 88" wingspan and similar wing area and are not considered overweight. 

And I do have weight concerns (& not just for my waistline). I have to keep it below 15.4lbs until I get my B certificate due to the club's rules.

Hello BBQ,
Well maybe I may have just asked a question on the missing litening holes.  Seems you have done your study of the airplane and please ignore my comments.  The concept that some people use is if you need to stiffen the airplane then you add weight only after adding it for strength.  The classic example would be if say CG is off.  A good thing to do is to add dead weight like lead to achieve balance.  A better way is to add stiffener or structural members anywhere that will achieve balance.  Better structural balsa or wood than dead lead.
This concept is only a guide or a rule of thumb.  You are doing fine and I will be watching asking you about items that strike me.  You really do not have to justify as I am a novice and have my struggles too and I am always looking for another set of eyes on my work.  Lately people look at my threads and say nothing....I learn nothing from this site like that. 
P.S.  The big sticks have a week spot around the narrow area of the fuselage.  If you study it carefully make sure it can take a load in the both directions.  On direction that is bad is the lateral in some big sticks.  The fuselage maybe tapering too much and say you have a notch for a control horn...bam weak spot.  I have seen two designs of big sticks that this indeed was the case.  Very weak when a force hits the tail feather from the side.  Like a bad landing or hanger rash.
Adios,
Albert

BB Q She is looking good, coming along nicely.
Albert some intresting points there

Hello BB Q,
Study the connection of the vertical stabilizer.  There some designs that it is hardly anything.  I had intall a gusset the full length of the vertical stabilizer as it not stabbed into tail section enough for say tip over or just plane fatigue.  The gusset was on both sides of VS epoxies to as much of the fuselage.  Next time I am notching the VS by cutting it with two 1" notches that will go into a block of lite balsa as the gussets are noticeable and a little tacky.  I will be building mine soon as I have to get back into a tail dragger.  Is yours a tail dragger or tricycle?
Good luck,
Albert

Hi Albert. It's a taildragger and has been suitably reinforced in this area, of course.

Although I've only built a very few models, when doing the mount for the fin I like to make a very tight fitting mount on the floor of the fus for the fin to slot into. I usually make this with two rails that run the length of the fin (and sometimes more to spread the load further if needs be). Coupled with a good adhesive you then have the fin secured at two locations, making it much sturdier.

Hello BB Q,
You da man .  I was moving my big stick and was putting into my truck and just tap the tail in the weak axis and it snapped.  The weak axis is side to side.  I have studied your pictures and your plans/design show no such weak spot.  That is what we call " hangar rash".
take care,
Albert

The structure of the tail also has the grain crossed in places too. It's actually three laminations of 1/8" balsa, with a trellised section in the centre to save a little bit of weight.

BB Q,
Your picture on your name...I hope no cats were hurt during the filming.
Albert

That's what happens when the cat steals one of my curries!

I had been putting off mounting the wing to the fus for some reason. I get like this sometimes- avoiding doing a job because I've told myself it will be really difficult and come out badly. In this instance the original plan has the wing banded on and of course I wouldn't use that method on anything this size! In the end the job proved uncomplicated and pretty straightforward, as it usually does in these cases.

I made a series of four 3mm ply plates that were to mount astride the central wing rib and bond to the main spar, front spar and leading edge spar respectively.



I bored them to take 1/2" hardwood dowels as a tight fit and glued them in place.




Once bonded I offered up the wing to the fus and pushed it forwards so as to leave a register on the balsa F2. That done I drilled holes in the former and checked for fit. Satisfied, I glued a new 3mm plywood former in place- let's call it F2a in a vain attempt to look like I know what I'm doing!



I then drilled the ply in situ and check for fit again. Right first time- that's very unusual for me! 





I let in a bit of 3mm ply into the back of the wing to give me a strong base for the wing bolts to mount against.Inside it's filled with suitably sized TE section to make it solid. I'm using M6 nylon bolts to mount to the fus.

As I left for work this morning I had the rear wing mount drying on the bench. I'll bolt it to the wing and glue it into the fus hopefully tonight.

It's definitely getting there.

Are you going to build it with the ejecting stabilisers? That would be cool at that size... 

Hello BB-Q,
You show a careful style of building.  I like the way you carefully mark location of stuff like blind nuts.  The wing mount , I would have not been able to line up so nicely the first time.  In general I believe the wing holds the fuselage to it.  So the fuselage is going along for the ride.  You got it.   Just an observation, but you could have modified the interface of the fuselage up say 3/4" so it came over the wing.  Then you could have installed dowel in the LE of the wing into a block at the interface position.  But many ways to skin cats and launching them into orbit too.
take care and looking well built and strong  and tough.
Albert

Fus, fin, rudder, stab , elevator and front hatch are now covered and awaiting paint. I have to service someone's car at the weekend so that's the paint paid for.   Elevator is top hinged using the Solartex.

Need to sort out the undercarriage next, and akso do the servo bays and wing tips son's I can cover the wing.

How goes it BB Q ?

Fus and tailplane are now painted. Tailwheel has been made and is in. Have just found out that, despit it being a car paint (Carplan Hertz Yellow) , the stuff I've put on is not petrol proof!  Need to find some fuel- proof laquer to spray on.

Wingtips and servo bays are done. I also sheeted the area around the mounting dowels and now the wing barely fits- some serious sanding to do there! 

Last night I drew up the templates for the ailerons and flaps- I've employed some artistic licence here and used the fact that I don't have the plans present as an excuse!  Still have 24 scallops to cut out and cover though.

Undercarriage still hasn't happened. I might have to bite the bullet and just buy one, but I'm guessing that 12" tall undercarriages with a 5" wide mounting area aren't exactly a standard fit......

Carbon Copy do a 150mm x 300mm x 600mm (6" mounting face x 12"Tall x 24" spread) , but it aint cheap £49.99 in your choice of either Carbon or Glass-fibre.
http://www.carboncopyuk.com/acatalog/index.html They give discounts of £5 for £50 spend, but you would be 1p short for it. If you are interested you might be able to haggle.

   Tom

£50 for a bit of f/g is a bit scary though. 

I may still make my own. I can buy the 'glass and resin for less than that.

I thought that would give you the sh**s
You could make one from dural 2" x 1/8" , not sure of the length( I tin it is a metre) £8 from D B Sports: http://www.dbsportandscale.com/bits-umdercarriage.htm They will also make the U/C for you if you want. If 1/8 isn't up to the job you could double it up or fit cross wires and springs.
I have a red Pitts U/c, in the shed, I will measure it up later. I'm pretty sure the width will be OK but I don't think it will be 12" tall. At a guess I think it will be about 9". It has cross braces and springs as it tended to spread, with my not too gentle landings . If it is any good to you ,you can have it.


  Tom

I've just done a rough measurement of the Pitts U/c and it is only approx 5.5" high. It is about 6.5" wide and 4.75" front to back.


   Tom

I've got a set of these if they are any good.

2.67mm aluminium (still with plastic covering), approx height 200mm from axle to mount, each mount 70mm wide x 40 long (can be easily cut down). I've just tested one on the bathroom scale and 7kg is only starting to bend it and it still feels quite firm at 9kg (when I stopped as the scale face was starting to bend alarmingly from the point load!)

The (quick, bad quality mobile phone) photo shows them next to a 4 inch wheel for comparison.



Yours for a fiver + p&p. PM me if interested

Richard

Thanks both of you for trying to help. 

I've ordered one from Falcon Aviation for just over half the price of the Carbon Copy one.

Last night after work I made the templates for the ailerons and flaps. I know it doesn't exactly need them, but the weight penalty is negligible and it gives me something new to play with.

I thought the original control surfaces were a bit too narrow to make good flaps (just 1 3/4" deep less the scalloping) but didn't want to ruin the look of the aircraft either, so I came up with a comprimise. I made them 2" deep at the start of the outer most scallop and tapered them to 4" deep at the innermost part of the flap. Here's them ready for cutting:



Then this morning before work I got the wing sanded back so it fits in the fus again    and tried out the new control surfaces for size.

Apologies for the photo, but SWMBO didn't fancy holding it up so I'm afraid it's my ugly mug again!



And another, taken from Mini-me's bedroom window upstairs:

Well done looks darn good to me.

Glad you got sorted . Model looks really good, should fly well.

   Tom

Hello BBQ,
It is very big.  What torque of servos are you using at the rudder and ailerons?  Have you worked out all the control rods and such?  Should finish well and you will have a fine flyer.  What is the weight as shown in photos above?  Predicted final weight?
take care,
Albert

Hello BBQ,
It is very big.  What torque of servos are you using at the rudder and ailerons?

The servos are all 6kg TowerPro SG5010 with the exception of the rudder, which is a metal geared Turnigy 15kg item. Not that I think that it needs it (my 80" 16lb Eurobat would only knife edge at full throttle and with full rudder deflection, but would do it on a 5kg servo) but because I have one spare and it doesn't hurt! Also, the extra weight at the rear might help with the balance.

  Have you worked out all the control rods and such?

 

I'll be using carbon rod with M3 threaded bar glued in and metal links. The longest control rod is the rudder at approximately 14", the rest are around 10". The throttle and choke are to be linked with snakes (which reminds me- I'm currently out of snakes).

Should finish well and you will have a fine flyer.

I hope so- I'm very pleased with it so far.

 

What is the weight as shown in photos above?

5lb 12oz

  Predicted final weight?
take care,
Albert

Fus 3lb 2oz
Wing 2lb 10oz
Engine 4lb 8oz (including muffler, spinner and prop)
Electronics 2lb 6oz (8 servos, 3300 3s lipo, regulator, rx, CDi, AA pack loads of HD extension leads)

Yet to be added is the undercarriage and main wheels. U/C is fiberglass and the wheels are alloy/rubber 3.25". As the U/C is yet to arrive I can't weigh it!

Let's assume 1/2lb?

Then add 1lb for covering the wing and painting it?

Should come in just under the magic 15lb mark ready to go. If it's slightly over I can use a much smaller lipo for the electronics as the one I've got earmarked for it is pretty heavy.

Hi BBQ

Why the 3S Lipo rather than 2S?

Hi BBQ

Why the 3S Lipo rather than 2S?

No reason other than the greater capacity (I use a switching regulator so can take advantage of it). I think I'm going to be using a smaller one though, probably a 2200mAh, as I've never used more than 750mAh from one of those in the Eurobat.