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Slider Glider! My take on a home design sloper


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Finished fuselage photos: Easy fit for the servos, RX and SBEC (alongside where the battery fits. The white Velcro in the 3rd photo is where the 500g of ballast sits. There’s a couple of dowels e

Hi fellow frustrated flyers! Thought I would give you something to ponder, poke at or muse over during this time of lockdown. Last Easter the weather was totally different, strong winds and

Thanks Mike. Maybe a trip to your neck of the woods for a day flying once social isolation is lifted. Do you allow visitors to your slopes? Next stage is to work more on the wing. This is a built

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CTR

Great, thanks. I was looking but there is no indication as to where it may be. 😃

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Wood Gnome

Hi Neil just seen this the Mk 2  looks excellent I am sure it will fly a treat and be even more capable than your Mk 1 which had a really impressive  performance range. I hope  that I will get to have a fly with this one. I don't think I can add anything to the technical debate that you have not already had about the  incidence flying it will prove that.  Just looking at your pictures and the ratio of ailerons and flaps to the chord I would say that personally I would prefer slightly wider surfaces for your next wing as they will then need to move less to give the same effect, which is probably slightly more efficient, I believe  20- 25% is a rough guide yours look about 20% at the tips a little less at the root but should give  well balanced control. 

Just a thought on the security of Phase 6 wing mount shear plates, I was also a doubter when first flying my Phase 6 almost 20 years ago however it has now done at least 200 hours many fully loaded with ballast and the only time they have sheared was on landing when something stopped a wingtip whilst the fuz carried on just what they are there for. 

Keep up the development work on this as you have a winner here and I think there is a lot more interest in wooden models at the moment and I can  see an electric conversion being really attractive for us flat earth pilots.😄

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StraightEdge
On 15/04/2020 at 14:51, CTR said:

(Left handed shot on my phone! Is there a way to rotate photos here?)

 

Rotate photo on the phone (or computer) first, then upload.

Great project!

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CTR

Thanks for the input guys.

Would be pleased to have your feedback Paul once you have a chance to fly the rev1 😉 What better person than the one who already has experience of the first!

I’ve taken on board the feedback from John and Paul regarding the ailerons and flaps. Redrawing nearly completed for the rev2 wing.

What are peoples thoughts regarding my idea of a transition from AG40D to MG05 at the tips for the next wing?

At this rate, there’ll be umpteen combinations to compare once restrictions are lifted and we can get airborne again! I thing I’ll have a go at modifying the first fuselage so it can take bolt on wings too. Then I have two AOA setups and who knows how many wings to try by then. 

Sounds like a good reason for another trip of a few days up the hill with a plethora of models again :)

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oipigface

I did think of a new thread for this, but since wobbly all-moving tailplanes have already been mentioned here, I thought I would carry on the conversation. On his website www.favonius.com, Graham Woods suggests a design for an AMT bearing that he suggests is rock-solid and slopfree. These are both fine qualities. The design centres (literally) on a piece of 10mm dia. aluminium bar with a hole drilled lengthways through it. The hole takes the rear joiner - the one around which the tailplane rotates. Graham says he manages to drill this hole without a pillar drill, and claims that it might be easier with one. I’ve tried this afternoon, with a degree of success that falls a little short of perfect. 
I’ve checked that the drill bit is properly aligned with the table. I’ve put the piece to be drilled into a vice with square jaws, and checked alignment at right angles to the jaws before tightening it up. But I’ve wound up with a hole that is about 0.5mm misaligned in a 17mm length. That’s a little over 1.5degrees off. In Graham’s design this matters, because as I understand it this bearing is fixed to the tailplane joiner, so the tailplane will move a with twist, which may be even worse than a wobble. 
Any  idea how I can drill this accurately? I’ve tried a jig which I cobbled together from wood, but the result was even worse.

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satinet

Your drill might not drill accurately. You can get wobble on the chuck.  What's known as run out.

It's really difficult to drill very accurate holes with a hand drill in my experience. 

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CTR

What’s the drill diameter?

Is it the drill wandering / bending?

Was there a small centre pip in the face of the 17mm length of 10mm? Sometimes this happens when using a parting off tool not exactly on centre height.

Could try using a centre drill to spot the position first.

Do you have anyone nearby with a lathe, if so that’s the easiest way to get it true.

I was considering using the same method of AMT for the next fuselage but don’t understand the advantage of 10mm diameter. Any slop is totally dependent on any clearance between the rod and bearing, along with the distance between the two bearings. The weight of the 17mm x 10mm aluminium is going to be more than a couple of miniature ball bearings. These are readily available with 3mm, 4mm and 5mm I.D. Flanged versions are easy to fit into thin sheet sides too. Cost: <£1 each.

Neil P

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EssexBOF
On 12/04/2020 at 21:18, SilentPilot said:

It’s funny because I prefer throwing my MiddlePhase about with its elastic band retained wing, my Phase6 on the other hand uses a nylon shear bolt to retain the wings (and a weak link plate). I’m terrified of this setup shearing under Aerobatic G forces.

I think most flyers under estimate the strength of nylon bolts.  I did have chart for Nylon 66 bolts, which I cannot lay my hands at the moment, but they are far stronger than you think. Certainly in regard to G force, but will give in a bad crash. On my Watts New 3.8 metre span, the M6 nylon wing retainer bolt has never given way, although the M5 rear alignment one does, due to the wing pivoting around the M6 retainer, so placing a shear load on it.

BTW I only use Nylon 66,not those cheap black moulded ones which are usually moulded from re claimed plastic.

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SilentPilot

I guess it's the placebo effect (but maybe in reverse!) 

That bolt is designed to fail so I'm petrified of it actually doing so in flight...

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oipigface
17 hours ago, satinet said:

Your drill might not drill accurately. You can get wobble on the chuck.  What's known as run out.

It's really difficult to drill very accurate holes with a hand drill in my experience. 

I agree, Tom. That’s why I’m using my pillar drill!

 

16 hours ago, CTR said:

What’s the drill diameter?

My most successful attempt was done by starting with a 1.5mm drill to a depth of about 1mm. Then I used a 2mm drill, trying to adjust any deviation from true centring by eye. I carried on in this way, up to the desired final sized hole of 5mm.

 

17 hours ago, CTR said:

Is it the drill wandering / bending?

I don’t think so. The main problem is not the actual drilling, but getting the hole straight down the middle. I’ve checked the drill press for alignment, and the vice that I used to hold the piece while I was drilling. I wonder if it would help to alternate the end from which I do the machining while I’m going up the drill sizes.

 

17 hours ago, CTR said:Was there a small centre pip in the face of the 17mm length of 10mm? Sometimes this happens when using a parting off tool not exactly on centre height.

Could try using a centre drill to spot the position first.

Do you have anyone nearby with a lathe, if so that’s the easiest way to get it true.

Centring isn’t really the problem, I don’t think. It’s more finding a way of holding the piece at the correct orientation in the drill press. Here are a couple of photos. The top one shows the ‘entry wound’, the bottom one the exit, which is about half a mm out.

6B8C0824-F5FA-4E42-A66C-4651851574F3.thumb.jpeg.9189f0dee388310ff568ab2883c9950b.jpeg
 

9DCE0E94-2502-472A-9F6A-1320D2FC6004.thumb.jpeg.cbbf89b03cb6ce1df89d3a9c015692cf.jpeg

There is a guy over the road who has a lathe, but I wouldn’t learn anything by getting him to do it for me.

17 hours ago, CTR said:

I was considering using the same method of AMT for the next fuselage but don’t understand the advantage of 10mm diameter. Any slop is totally dependent on any clearance between the rod and bearing, along with the distance between the two bearings. The weight of the 17mm x 10mm aluminium is going to be more than a couple of miniature ball bearings. These are readily available with 3mm, 4mm and 5mm I.D. Flanged versions are easy to fit into thin sheet sides too. Cost: <£1 each.

 

Yes, your doubts are not misplaced! Perhaps I should contact Graham and ask him!

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CTR

I suspect your problem stems from the bottom face of the aluminium not being true to the side. If it was, then a good result would be more likely if the flat, true face was placed on the drill table. Drill most of the way through, lift it with a piece of scrap wood under it and complete the drilling.  Maybe holding it with a pair of gas pliers so it can float to line up with the existing part drilled hole.

How to get one face flat & true: put it in the drill press chuck and bring it down onto suitable emery paper, spinning ‘til flat.

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CTR

Another thought: convert your pillar drill into a lathe.

1/ Clamp a piece of metal (12mm or more thick) to the drill press table, having previously drilled and tapped an M4 hole in the side of it, coinciding with the place your going to do step 2.

2/ Drill a 5mm hole in the metal, first ensuring it won’t move.

3/ Put the drill into the drilled hole, point up. Tighten the screw in the cross drilled hole to clamp it in place.

4/ Put the aluminium bar into the drill chuck and drill the hole from the bottom up.

You may need to grind a small flat on the drill shank for clamping to stop is spinning.

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oipigface
On 01/05/2020 at 14:03, CTR said:

Another thought: convert your pillar drill into a lathe.

1/ Clamp a piece of metal (12mm or more thick) to the drill press table, having previously drilled and tapped an M4 hole in the side of it, coinciding with the place your going to do step 2.

2/ Drill a 5mm hole in the metal, first ensuring it won’t move.

3/ Put the drill into the drilled hole, point up. Tighten the screw in the cross drilled hole to clamp it in place.

4/ Put the aluminium bar into the drill chuck and drill the hole from the bottom up.

You may need to grind a small flat on the drill shank for clamping to stop is spinning.

This would be OK if it were not so difficult to centre the hole when it is upside down on the drill press! I did try it half a dozen times, and none of my attempts were close to being centred.

Anyway, folks, thanks to all who have made suggestions. I have finally made an acceptable hole which is close to centred, and very close to straight. I put the aluminium rod in a vice with one end of a 700mm CF rod installed through the hole and measured the wobble at the other end as it was rotated. The deviation was so small it’s hard to be sure exactly how much it is. Definitely less than 1mm.

How did I do it?  Carefully! Starting with a 1.5mm drill, I made a guide hole at each end about 1mm deep. I then checked centering with a rule. Using a 2mm drill and correcting any deviation from centering, I next drilled down about 5mm at each end. A 2.5mm drill helped the two holes meet in the middle and I was able to put a 2mm rod through the entire hole. (I haven’t got any 2.5mm rod in stock.) Carrying on like this, adding 0.5mm to the diameter of the hole at each step, and drilling 10mm through from each end, I finally got an acceptable result, which is going to be installed in my project. This method isn’t quick, mind. It took me 6 or 7 minutes per mm. Here’s a photo. The piece is a little longer than I need:

D45E3B20-6841-491A-BEF9-4F0B96FE1810.thumb.jpeg.33d40c568d6ec88ed19751a8df4c6d81.jpeg

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oipigface
On 30/04/2020 at 19:39, CTR said:

I was considering using the same method of AMT for the next fuselage but don’t understand the advantage of 10mm diameter. Any slop is totally dependent on any clearance between the rod and bearing, along with the distance between the two bearings. The weight of the 17mm x 10mm aluminium is going to be more than a couple of miniature ball bearings. These are readily available with 3mm, 4mm and 5mm I.D. Flanged versions are easy to fit into thin sheet sides too. Cost: <£1 each.

Neil P

I haven’t responded to this point before because I’ve been thinking about it. You are of course right about where some slop might come from, but I don’t think the two factors you mention exhaust the possibilities. In particular, the whole apparatus (including the fin sides) needs to be as rigid as possible. One of the functions of the aluminium piece is to spread the load on the fin sides.  In this design, the aluminium bears the bellcrank as well as the joiner, and is fixed in place inside the fin with GF plates at each end. These plates serve to spread the load even more. Furthermore, it provides a more robust, larger diameter pivot for the bellcrank than the joiner, which is restricted in size by the thickness of the tailplane. Following your comment, I am inclined maybe to machine some lightening holes in it! 

I have an AMT in my Raptor ( built by Baudis). It has ball bearings in the fin sides. It works very well, and is very solid, but I don’t know what else is inside it! I agree that fitting ball bearings in a moulded fin is not hard. Locating them accurately  is another question.

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CTR

Well done.

Sorry for not making it clear in my previous post; it is important that the drilled hole to take the drill in reverse is done with metal securely held in place, and don’t adjust the drill head position. Then, the aluminium in the drill chuck should be exactly centred over the drilled hole.

 

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oipigface
1 hour ago, CTR said:

Well done.

Sorry for not making it clear in my previous post; it is important that the drilled hole to take the drill in reverse is done with metal securely held in place, and don’t adjust the drill head position. Then, the aluminium in the drill chuck should be exactly centred over the drilled hole.

 

Of course! Why didn’t I think of that!

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satinet

A given slop will be less bad the bigger the diameters involved. E.g 0.25 mm of lose fit on a 3mm rod would mean a lot more slop on the tail than the same miss fit on a 10mm diamter rod.  The percentage is much higher so the angle of wiggle is more.

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EssexBOF

On the later glider designs I built, that used an AMT, I reversed engineered it by having the tail plane halves pivoting on the wire, that was fixed into the fin. This meant there was no slop at all. True the wire had to remain in the model, so I used to loop a piece of fuel tubing over it for storage.

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CTR

Sorry to say,  if you have 0.25mm clearance of a rod in a tube (assuming they are both parallel) and in this case the tube is 17mm long,  the resulting angle is +/- 0.8425243 deg of 'wiggle' irrespective of the diameters in question.

imagine the rod is loaded so at one end it is against the top of the tube, the other end is against the bottom of the tube. That's 0.25mm clearance down from the top of the tube.

Consider it as a simple triangle made up of 1/ the upper inside edge of the tube, 2/ the top outer edge of the rod and 3/ the clearance dimension forming the 3rd side of the triangle. Makes no odds how far away the other side of the tube & rod are.

 I agree that the percentage of diameter is different which influences the wear characteristics; the smaller diameter will suffer earlier in life than the larger diameter.

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