Current Glider Project (lot of images!)

[dr_gn]

Here are a few pics of my current project: it's a slope soaring glider 'Bluebird' based upon a old design by a fellow gliding club member.



It is unusual because it has a V-tail, and also has twist wings (or 'pitcherons'). As the term suggests, the entire wing halves pivot either in the same direction and/or opposing directions, giving pitch and roll control, rather than the usual ailerons and elevator. This gives a very efficient, low drag design.

The model is built around a 30mm diameter glass-fibre fishing rod. Ply fuselage sides and balsa top and bottom sheeting are epoxied to the 'boom'.



Solid balsa tail fins are carved to symmetrical aerofoil sections and epoxied to the boom in a jig:



Wings are hot-wire cut foam covered with glass fibre. The wing section is not as per the original design, this one should give a much better lift:drag ratio.





They contain main spars made of balsa, carbon tube and brass pivot tubes, and stub spars for control rods and safety hooks:





The wings are held to the fuselage primarily with small magnets within the spars (this is an experiment!):



Glass cloth and resin are layed up over the foam cores and compressed until cured:



Two standard servos are built into a removable cassette which goes inside the fuselage (this is also an experiment!) The original model featured a mechanical mixer to give the correct control combinations. I decided to update the design by using electronic mixing:



Just needs final sanding and painting of the fuselage and hatches, setting up and balancing and then testing!

Cheers.

Edited by dr_gn on Tuesday 8th September 21:25

[tr7v8]

That looks interesting. Getting the throws right will be interesting!

[dr_gn]

tr7v8 said:

That looks interesting. Getting the throws right will be interesting!

Test flight later this afternoon...got one chance to get them right for this one I think!

[dr_gn]

Test flight went fine - flew in turbulent South Westerly, gusting up to about 40 mph:







Might even paint the fuselage now I know it flies!

[Quick silver]

dr_gn said:

It is unusual because it has a V-tail, and also has twist wings (or 'wingerons'). As the term suggests, the entire wing halves pivot either in the same direction and/or opposing directions, giving pitch and roll control, rather than the usual ailerons and elevator. This gives a very efficient, low drag design.


They contain main spars made of balsa, carbon tube and brass pivot tubes, and stub spars for control rods and safety hooks:

Do the wings pivot on a spar positioned near to the front of the wing with the servo's mounted to the rear?

dr_gn said:

The wings are held to the fuselage primarily with small magnets within the spars (this is an experiment!):

What an excellent idea, the magnets need not be to large/heavy if they were rare earth 'Neodymium'.....why hasn't anyone thought of doing this before?

How have you bonded the magnets to the wing? & do they interfere with the servo's or receiver?

[perdu]

that looks like a great project dr_gn

I like the magnets in the roots ideas too

have many hours flying her happily

I do like innovation like this

will it be light enough to spare some "lift" for paint I wonder?

all those crappy gliders I built as a kid..

come back to haunt me when I see lovely planes like yours

[dr_gn]

Quick silver said:

dr_gn said:

It is unusual because it has a V-tail, and also has twist wings (or 'wingerons'). As the term suggests, the entire wing halves pivot either in the same direction and/or opposing directions, giving pitch and roll control, rather than the usual ailerons and elevator. This gives a very efficient, low drag design.


They contain main spars made of balsa, carbon tube and brass pivot tubes, and stub spars for control rods and safety hooks:

Do the wings pivot on a spar positioned near to the front of the wing with the servo's mounted to the rear?

dr_gn said:

The wings are held to the fuselage primarily with small magnets within the spars (this is an experiment!):

What an excellent idea, the magnets need not be to large/heavy if they were rare earth 'Neodymium'.....why hasn't anyone thought of doing this before?

How have you bonded the magnets to the wing? & do they interfere with the servo's or receiver?

The pivot is at the centre of pressure of the wing, which at the root is nearer the front than the back. This gives the minimum load on the servos. You can see the pivot in the middle here:



The servos are arranged symmetrically about the pivot spar so that one acts on the back of one wing, and the other acts on the front of the opposite wing. You can see the drive holes in the picutre too. One hole is for a drive, the other for a fail-safe hook! Its the opposite way around for the other wing.

You can see the magnets here - they are the little silver cubes inbetween the brass and carbon (there are enough for two wing sets here). BTW magnets may well have been used on other designs before, no idea of the details:



It's all Epoxied together to form the spar in the first picture above.

The magnets do work, but I chickened out and added small o-rings on hooks to act as fail safes!

In high-g manouvers, the wings flex, but that is how they are designed to work.

Edited by dr_gn on Tuesday 1st September 14:08

[dr_gn]

perdu said:

that looks like a great project dr_gn

I like the magnets in the roots ideas too

have many hours flying her happily

I do like innovation like this

will it be light enough to spare some "lift" for paint I wonder?

all those crappy gliders I built as a kid..

come back to haunt me when I see lovely planes like yours

Thanks very much! It's sometimes frustrating not knowing whether something will work well if it's an experiment. Like I said, this model is a slightly refined version of one I've seen before, but still you never know!

It's not a light model. My fibreglassing skills leave a lot to be desired at the moment, and so the wings are heavy. A coat of paint won't make much difference. I can get lighter, stronger servos (for a price) and also lighten the pivot rod (which is piano wire) by making a carbon/wire composite version. I'm considering making another lightweight pair of wings for low winds.

If you can build plastic kits to your standards, then a glider like this will be no problem. Just takes patience and a willingness to learn from mistakes!

[Quick silver]

I have many models, from shock fliers, through DS to a large powered spitfire & the closest thing I have to your fine example is another version of the 'Bluebird'.......except this ones a 100" rudder/elevator powered glider & it came straight out of a 'JP' box (ARTF)

[dr_gn]

Quick silver said:

I have many models, from shock fliers, through DS to a large powered spitfire & the closest thing I have to your fine example is another version of the 'Bluebird'.......except this ones a 100" rudder/elevator powered glider & it came straight out of a 'JP' box (ARTF)

That looks a fine model - would go well on the slope I bet. Have you ever tried it? I learned on a rudder elevator Middle Phase II, then progressed to the aileron wing, which I think is easier to fly.

I've got an electric Extra 300S which was ARTF, only cost £60 including brushless motor and gearbox. Way better value than my V1.1 Several times during building mine I thought 'never again', it's a lot of hassle, and materials cost a lot. Mine's cost about £100 in total, and because of the overweight wings I might end up building another lighter set.

Ho hum. I've never geen good at economics!

Looks like your Bluebird costs about £75? How the hell do they do it for that price? I'd want that just for covering those wings, never mind building them and producing a fuselage!

Edited by dr_gn on Wednesday 2nd September 09:51

[Quick silver]

dr_gn said:

That looks a fine model - would go well on the slope I bet. Have you ever tried it? I learned on a rudder elevator Middle Phase II, then progressed to the aileron wing, which I think is easier to fly.

I've got an electric Extra 300S which was ARTF, only cost £60 including brushless motor and gearbox. Way better value than my V1.1 Several times during building mine I thought 'never again', it's a lot of hassle, and materials cost a lot. Mine's cost about £100 in total, and because of the overweight wings I might end up building another lighter set.

Ho hum. I've never geen good at economics!

Looks like your Bluebird costs about £75? How the hell do they do it for that price? I'd want that just for covering those wings, never mind building them and producing a fuselage!

Rudder/elevator is a difficult way to learn to fly, slow/delayed reactions & difficult to recover from a stall.......I started learning on mixer ailerons with a 'Combat 50' slope soarer & quickly got into the stride of it - that was until I tried my first fast-ish powered model & stuffed it into the ground. It was then that I turned to a PC simulator & I've not looked back.......every prospective flier should have one!


I've had the Bluebird for about 5 years (£80 at the time), during which time I've flown her a lot, she's very good on thermals. I tend mostly to fly a 'Gulp' DS off the slopes these days & have a 'Fling' & an 'Alula' for calmer days......sometimes flying a 'Twin Jet' or on the very odd occasion the 'V-Mar Spitfire'

I also reinforced one of my 'Shock Fliers' by coincidence it's an Extra 300s, by doubling up on the depron & gussetting with balsa, now she's an excellent/fun stunt flier that is able to cope with a lot more wind than standard.......great for jumping over the fence & into the field for a spot of 3D fun.

[dr_gn]

Here's the finished item:



Just needs some smooth lift to trim it now!

I'm already planning a mould to make some carbon wings...

[perdu]

looks very good finished

happy flying

[dr_gn]

perdu said:

looks very good finished

happy flying

Thanks Perdu.

Finishing touch was an 'endorsement' from Boeing's chief test/development pilot for the F/A-18, Ricardo Traven, who happened to be visiting work. I only took the wing in to get some advice on how to make carbon wings, but it turned out the guy's a big gliding enthusiast with several hundred hours on full sized machines, so I took the opportunity to get the wing and some Farnborough pics signed. Top bloke.



I *nearly* said "you can be my wing-man any day", but didn't.

Cheers,

Edited by dr_gn on Wednesday 9th September 23:21

[dr_gn]

I really need to work on the "landing" bit...

[perdu]

Ahhh

yes but no

at least it did land

my mate who is very into free flight rubber powered "stuff" was flying in Sutton Park near us last year

(competition day it seems)

His Wakefieldy* thing still hasn't come down

held aloft in the tree canopy we think

I searched all winter for a glimpse but no chance

• do they still have Wakefield Free flight?

For all the damage on yours it looks to be a very fixable break, how has it been flying?

And have you used it often G?

B

[dr_gn]

perdu said:

Ahhh

yes but no

at least it did land

my mate who is very into free flight rubber powered "stuff" was flying in Sutton Park near us last year

(competition day it seems)

His Wakefieldy* thing still hasn't come down

held aloft in the tree canopy we think

I searched all winter for a glimpse but no chance

• do they still have Wakefield Free flight?

For all the damage on yours it looks to be a very fixable break, how has it been flying?

And have you used it often G?

B

Perdu,

Oh yep, it's had a fair few flights! The problem with twist wings is, when the wing(s) stall, you just have to sit it out until the nose drops and you get enough speed up to do something about it - probably about 20 feet or more vertically. After stalling, you don't even have an elevator control to put the nose down a bit more during the 'dip' because all control is with the wings. I was flying it in marginal conditions on Tuesday, and it stalled on an upwind turn. Should have known better. It stuck into the ground about 6" . Wednesday's weather was absolutely perfect for it, but unfortunately it was in two pieces, so I had to make do with another, more conventional model. Ah well! As you say - it'll mend!

No idea about free flight really, although our club does have an active free flight contingent. Strange people...

Here's our flying site in the Peaks - any excuse for a trip out for an hours' flying of a lunchtime!





Cheers.

Edited by dr_gn on Thursday 24th June 21:17

[perdu]

Shudders...

wings stalling [thinks]

how about fitting L.E slats sprung to shoot out if airflow disappears

No

just a joke - too complex I'd expect

parachute on stalling?

My mind's all off on various tangents now

nice place to fly

very nice

Carbon fibre skin on fuse-pod, would that strengthen without a masive weight increase I wonder

excuse typical disjointed thinking ...

[dr_gn]

perdu said:

Shudders...

wings stalling [thinks]

how about fitting L.E slats sprung to shoot out if airflow disappears

No

just a joke - too complex I'd expect

parachute on stalling?

My mind's all off on various tangents now

nice place to fly

very nice

Carbon fibre skin on fuse-pod, would that strengthen without a masive weight increase I wonder

excuse typical disjointed thinking ...

Perdu,

It already had glasscloth and resin around the fuselage, smoothed down of course. Carbon might be marginally better, but the thickness we're talking about would still be brittle.

The answer is simply not to crash it!

Cheers.

[anonymous-user]

Hi gn,

What is the pitch response like with this system?

As you'll know, the wing twist will increase/decrease total wing lift - so your pitching moment is wing lift multiplied by the distance from wing centre of pressure to the CG? (its been a while since I've done any aerodynamics).

So when you are using pitch control do you find that the aircraft pitches up and down or does the glider seem to go straight up/down?