Aquila

[Martyn K]

I think that there was a MF poll earlier this year on 'what will we try this season?'. I said Thermal Soaring and this is my effort.

The design is is Lee Renaud's (World Champion I think) from 1977 and was kitted by Airtronics.

Why this model?  Well there was new Facebook Group formed - "Classic Gliders and Modern Hybrids" and one of the first posts was a photo of this model and I thought it looked absolutely lovely. A Google around and the plan was sourced from Outerzone. A request here on this forum and a very kind forumite offered to print me a set (for which I shall be forever grateful Nigel - thanks again).

All I had to do was find the time to start building.

Dylan at Lasercraft Services cut me a set of wing ribs (from lite-ply) with lots of lightening holes after I plotted them using Profili.

So making a start - unusually for me, I started on the fuselage.

Sides are cut from 3mm liteply. These are quite slim and highly flexible. Left and right sides and triangle section longerons glued into place.

The nose has quite a sharp curve so it may be necessary to moisten the wood or cut nicks. I used the former technique.

The top of the fuselage has spruce doublers up to the TE of the wing.

The two main formers are 3mm ply. I sandwich these between two old UPS batteries to keep them vertical while the glue dries. Triangle braces are glued in on one edge to increase the contact area.

The second side was glued into place along with the servo rails and the batteries used to make sure there was good glue contact.

You can see in this shot that the root rib doublers (actually triplers - there are 3 of them) are sandwiched up and allowed to dry

The position of the main wing joining tube was marked and the hole drilled on a pillar drill to ensure it was vertical. A second smaller hole (2mm) was drilled at the TE peg position. The rods/tubes are pushed through and checked that they are horizontal and parallel. Don't want any twists here..

A shot showing the servo rails. I will be using mini servos (MG-90S) so they will be located on a ply plate between these rails. 4 servos will be used - Rudder, Elevator, air brakes and tow release (for a tug).

 

The noseblock should be solid pine, I dont have that so mine is laminated from 2 x 1/4" spruce, 4 x 1/4" balsa. It makes it somewhat easier to carve.

More to come

M

 

 

Edited By Martyn K on 26/06/2014 23:04:16

[Martyn K]

Before I could go any further with fuselage, I needed the fin and tailplane platform making.

The fin was built over the plan. It a simple balsa outline built over the spars. This means that the LE and TE need to be packed up by 3mm to allow for the thickness of the spar.

and

and

Although not shown on the plan, I have added 1/16" sheet spacers on the ribs to build up the the section. Gives something for the film to stick to.

The tailplane support is made from 1/16" ply with a balsa spacer at the front. The fin post at the rear is spruce (another change from the plan which shows balsa). Robart style hinges (4 off) have been used and epoxied into the fin post. At the moment, the rudder is simply pushed into place and checked for free movement. I'll take the rudder off before I cover it.

The next job is to fasten the fin to the fuselage.

Note that the noseblock has been added. It was tapered slightly and the glued and clamped and allowed to dry for most of the day.

With the fuselage in the jig, another alignment check making sure that the rods and tubed in the wing and tail pivot all align and all are parallel with the baseboard. The fuselage is still very flexible and will need to have the upper decking added while still in the jig. Note the batteries making sure the fin stays vertical and the centre battery pushing both fuselage halves down.

Forward looking shot into the noseblock and ballast hole.

Finally (for tonight) clamps holding the fin/tail platform in place while the glue dries overnight.

More to come..

M

[Dylan Reynolds LaserCraft Services]

subscribed

[Tony Bennett]

looks like another interesting build from you sir.

[Martyn K]

TYVM... It should be a fairly quick build and a bit different to the stuff I normally do. I have got another classic Aerobat to start after this but I MUST get the Magic finished as well.

Then we start work on the Chippie. I have even ordered a wood kit for that one.

[Erfolg]

I thought you may like to know something about the designer of the Aquila, Lee Reanud, so have provided this link.

I have flown for many years a Sagitta, probably the last glider design by Lee, flown in the UK World Championship by the USA team.

Much of the design of the Aquila can be seen in the Sagitta, having continued the methods, use of materials and detail design, but either minimised or and beefed up some what.

A interesting build, like my own model, a historic glider. Still much better than many non glass gliders of today.

[Nigel Dell]

Great start Martyn!

I am going to have to hunt out my Aquila parts now, all I need to do is build a set of wings and possibly the tail plane, then I want to do a complete Grande, I have also found a complete Sagitta 900 kit too, just not enough time

I will dig out both the wood and moulded fuz's and get the plug made for the canopy, that might be useful.

Keeping tuned into this build.

Cheers

Nige.

[john stones 1 - Moderator]

Is it only going to be rigged for towing Martyn ? or bungee as well ?

I fancy a glider myself but was thinking of b/less to gain height with, it adds weight but makes me independent

John

[Erfolg]

I have been pondering your build, perhaps more precisely the model.

I remember that my first Sagitta was not built with the Pine nose block, which turned out to be a mistake. The second was, I am assuming it is much the same, that is the block is pretty much shaped and is sandwiched between the ply sides. This produced a much stronger front end. With built up gliders, the extra weight of the block did not matter at all, as models were always tail heavy. I recognise the spruce lower longerons, they were copied into the Sagitta. Although it was recommended that the body was covered in light weight glass cloth and epoxy, I do not remember the either the Aquila or the Grande doing this?

I was then thinking at the beginning of the 80s I was the competition director for our club. We would regularly run 4 major competitions a year, where we would get +60 entries, my main concern was could I slip in an extra 10 on the day, or would my matrix be shot to pieces.

Little did I recognise that this was the high point of the BARCS league, That the Aguila, the Grande, Phoenix 100, Mean Machines were the pinnacle of built up models. That the composite bodies and rod blank booms and bagged wings would lead to the comparative death of thermal gliders.

When I see the all moulded models of today and the other extreme of Avas i see a far superior group of machines. Yet the gliding community at the competitive level seems to be just a few, as low a s six at a comp.

On that note I hope your build goes well and you obtain the fun that we used to get. I still cannot get over how things changed in my sabbatical for 20 years from gliding/ modelling.

I will watch the build with interest.

[Martyn K]

Thanks for the link and the history Erfolg. I am inclined to agree with you regarding the adoption of high tech materials in competitive aeromodelling. While it is clear that modern models are far more competitive, the comparatively high cost and I believe lack of involvement in the build process has caused the decline in all competitive disciplines. I have always believed that the real golden age of aeromodelling was the 70's which heralded the arrival of reliable electronics, the appliance of science and technology in design and a far better understanding of materials. I think that applied to all the aeromodelling disciplines.

John - the model will have a towhook for a bungee launch as well as a tug release. I'll make up all my own hardware.

Nigel - its a lovely design and I am glad that I am sticking to the plan. I am not familiar with the Sagitta. I'll take a look.

Best wishes

M

[Erfolg]

I am sure you are correct Martyn in that was approx the golden era for the mass participation of flying RC model gliders.

Now it is easy to understand, as the very same issues effect nearly every interest. It is the balance of ease of involvement, the cost of involvement, and that success is possible by the application of your skill and knowledge etc. A obvious similar sport, is motor sport, which is now primarily the province of the wealthy and high technology companies. Gone are the garden shed clubman 7 racing cars etc.

I have provided a link to a image of a Sagitta tail unit. It is a Aquila, refined by minimisation, optimisation process. In fact the whole airframe is the same, smaller and stronger, with no weight gain, both being circa 9 oz per ft^2 loadings.

Keep posting the pictures.

I would like to build another Sagitta 900, but having a large number of composite fuselages, a large number of wing sets, in addition to a number of now electric gliders i never fly, I just cannot justify building one.

Still the Aquila does bring back happy memories, of flying field camaraderie and good competition. I was surprised to hear  the other day that Bill Haley still competes, most successfully, although his son is the star today I understand. So the odd pilot also has manage to stand the test of time to, not just the Aquila!

Edited By Erfolg on 28/06/2014 11:27:56

[Martyn K]

A little bit more progress in the last couple of days.

Lite ply sub formers added for the front and rear canopy sides and the upper block added and sanded to shape.

(Sorry about the odd colour).

The rear upper decking has also been added witth the 'hump' just behind the canopy. A little more tricky than I anticipated..

The rear upper deck was actually made from 2 pieces, carefully spliced with the rear part being slightly softer/lighter density wood.

(We apologise for the break in colour transmissions - normal service has been resumed)..

So - lots of sanding and planing to get the deck shape just about right. - quite pleased so far.

The next job is getting the linkages done. This means making up the all flying tail 'elevator' horn

Marked up from the plan onto 16swg aluminium - the included angle is 100 degrees and roughly cut ready for drilling and final filing.

Probably tomorrow.

More to come..

M

[Martyn K]

Got started on this after lunch again today and worked through to about 9:30pm. - amazing how much you can get done on a good workshop stretch. I also had a good session at the field this morning. Its been a cracking Sunday..

Finished filing the all flying tail horn and added a brass bush to keep it central in the fin cavity.

I had to remove some more metal from around the rear hole - it was quite a tight fit in the cavity.

With that horn ready to be located, I could start work on the tail fairing. 1/4" balsa and 1/32" ply caps around a 3/8" balsa core.

and

Not quite finished at the stage, still working on the slot for the rear tail joiner which is driven from the rear hole - above. About 30 minutes with a file got it right.

Now I can get the goldenrods in place. It looks tight, in reality it all went in quite easily. I have epoxied the clevis onto the threaded rod - this will be sealed up and I dont want it coming undone..

With the goldenrods in place, I can sheet the lower fuselage with nice light 1/8" balsa - grain cross ways.

The mount for the tow-hook and ballast plate is two 1/2x1/4 spruce beams with a retro 4BA captive Nut in each. I have also added a 1/16 ply sub-former to support the front beam.

The lengthways spruce beam is offset and is used to screw the tow-hook to.

This has been fabricated from some extruded 'L' shaped dural from B&Q - it should to strong and long enough..

The front lower sheeting is 1/8" lite-ply. clamped in place with countless elastic bands while the glue dries.

Finally for today, I have added a 1/8 x 1/4 spruce skid - the plan shows 1/2 x 1/8 but this looks better.

One thing I really enjoy doing is sanding ply. I love the patterns that appear as you sand through each of the layers. Also very useful for showing that the left side and right side are sanded equally.

Tailplane next..

Tug tow release ordered from HK UK.

More to come..

Martyn

[Martyn K]

On with the tailplane.. At first sight it looks very simple - a 1/4 x 3/16 outline plus simple strip ribs. The only tricky job is getting the joiners parallel.

Spars are fashioned in a similar manner to the fin - from tapered 1/8 sheet.

The joniers are inset (rather than drilled into the 2 roots ribs in each half. As you can see from the note in plan above, its easier!

Suitable slots were cut then filed out so that the tubes were a good fit. Don't rely on the plan though, take the measurements from the model - mine were 30mm spacing which just happens to be the same as the plan.. Note that the tubes are in one piece. This ensures that the joiners will actually be parallel and will line up.

The tubes need to be glued in at the same time as the 1/8 sheeting that bridges the two root ribs on each half - so a mixture of wood, PVA and epoxy and......

...weigh it down with a car battery and some UPS batteries to make sure that the glue is really forced into the grain.Leave it to dry while you cook tea and mow the lawn. (Note: the battery is So-lite - good job I didn't use a So-Heavy one).

When dry add the spars and centre sheeting on the other half of the tailplane. Note that it is all still in one piece. I have added the 1/16" triangles above (and below) the ribs to make up the section. the original didn't have these and they are not shown on the plan. When complete, separate the two halves using a fine tooth hacksaw.

Sand it all to a nice symmetrical aerofoil shape and check it fits - it does..

Still a bit hairy. I will also add some 1/32 ply facing ribs. One problem I have got is that I blindly followed the plan and uses 3/32" bore tubes for the joiners without checking I have got 3/32" wire which is bigger than 16swg.

Need to get some 3/32 piano wire from somewhere - alternatively, I'll use 3/32 pultruded carbon rod if I can get it. If I cant get that then I'll grind down some 14swg to fit.

More to come. Wings next

Martyn

Edited By Martyn K on 30/06/2014 22:38:40

[Tony Bennett]

looking goooood sir.

almost as nice as a certain spag bol.

[Martyn K]

Thank you Tony... Just about as messy as well.

[Martyn K]

No post last night. Busy fixing an electrical fault (in the semi darkness). However, some progress.

The HK tug towline release latch mechanisms that I ordered on Sunday from the UK warehouse arrived yesterday. Nice one HK..

These was fitted yesterday lunchtime. a 7mm aluminium extension tube through the nose.

So - on with the wing..

LE laminated from spruce and very hard balsa and roughly planed then pinned down. The TE is built up from 1/16" sheet balsa and cap strips glued into place. All weighed down while the glue dries.

The wing ribs were cut by Dylan at Lasercraft Services - excellent service as usual..

 

Lower spar added then before the glue dries, the ribs were glued down and slotted into place. Note pinned front and rear to keep them straight and upright..

When dry the slightly tricky job of getting a good root join can be tackled. The joiner tube (and joiner) is kept horizontal. To get the 4 degrees dihederal, the tube in the wing is angled downwards. So - the root ribs have to be tilted by 4 degrees to get a good fit. To complicate things, the root rib is also angled backwards so that it fits against a tapering fuselage. This is a bit too risky to attempt on the board, so the panel is jigged into position, joiners fitted, all lined up and clamped then the root and inner rib (as a pair) are glued in and allowed to dry.

Showing the angled joiner tube..

While the glue is drying on the root start work on the tip. The upper spars cant be added until the tip is supported at the right angle to the centre panel - 4 degrees = 31mm lift at the main spar on the last rib.

Build the tip panel the same way as the centre panel.

With the Tip glue dry, this is now propped up and carefully fitted to get good joints at the LE, TE and lower spar. A bit of sanding will probably be required.

The upper spars can be added. I have extended the rear spar out 2 bays to end it at the dihederal break. It is also tapered over the length of the last bay

Finally tonight, I have added the upper TE sheeting in the centre panel and fitted 1/16" sheet spacers to complete the triangle.. (yes - its upside down..)

This adds a surprising amount of stiffness and strength.

Quite pleased with that..

Things will slow down a bit now as I am away for a week from Saturday but got some packing/shopping and preparation to do.

More to come (sooonish)

 

Martyn

 

 

Edited By Martyn K on 02/07/2014 22:53:02

[Tony Bennett]

masterful work sir.

keep it up.

[Martyn K]

Cheers Tony.. I am enjoying this one. Takes me back to my yoof..

M

[Erfolg]

Martyn

I cannot but note that you have changed the wing ribs from balsa to light ply. From memory Lee normally made the wing root rib and the next 2 out of ply.

Is the change based on, cost, is it easier to laser cut ply, you wanted increased strength or some other reason. Part of my reason for asking is self interest, deciding if to make a wing which is originally specified as 2mm light play ribs, into one that uses 1/8 balsa or 2.5mmm light ply ribs (cannot get 2mm).

[Martyn K]

Hi Erfolg

As they were laser cut, I took the advantage of stripping out most of the material with the lightening holes. The result is that they are still much stronger but only a gram or so heavier than medium balsa. Cost wasn't really the issue, it was just convenience - I wanted a fairly quick build.

However, there is an error in the wing section that I sent to Dylan, I used the 'Aquila' section from the Profili database and scaled up my PDF drawings to 100% to check the wing chord. Unfortunately, the TE taper on the profili database section is thinner than the original (proper) Aquila section and as a result, the wing is about 7 or 8mm narrower chord to compensate for this (the TE was so sharp you could cut your fingers). The max thickness and position is correct - it looks like someone has modified the original and not flagged it with a mod suffix which is convention. I am not worried about this - mainly an irritant, but the section and cutting file really needs redoing using the proper section if anyone else wants to have a go at building this and not use my DXF file. I am not sure Dylan is aware of this - I must warn him. I can rerun the plot if needed.

If you look at this image you can see the line where the TE should have come to.

I have also found another error on the plan. It says that the top dihederal should be 4 degrees, but it is not. It should be about twice that. I spotted that this morning when I tried to glue the ply dihederal braces in and they didn't fit.. I'll cover that in the next update

BW

MArtyn

[Dylan Reynolds LaserCraft Services]

I am aware now Martyn, thanks. I trust other than a plotting error the ribs were easy enough to work with?

[Dylan Reynolds LaserCraft Services]

Oh and just to point out, I didn't plot them

[Colin Leighfield]

That's a beautiful model Martyn, it will look classic in the sky.

[Martyn K]

Thanks Colin - I have to admit it does look nice.

A brief update after a week away..

The second wing has been pinned down and assembled as the first wing.

The root ply doublers have been inserted. The joiner tube was packed out with balsa then a thick epoxy mix was poured in and the whole lot clamped up. One minor change - I have extended one of the ply doublers out an extra bay - people who read my rubbish will know that I avoid stress discontinuities as much as I can.

The PTFE tubes to carry the spoiler pull cords have been inserted. You can see the forward ply doubler tapered then infiled with a 1/16" web = grain vertical for webs. The rear doubler is extended one bay.

They pass through a 1/4" balsa block between the spars

The webs have been added on the first panel and mainly completed on the second panel

Interesting dihedral braces follow the dihedral angle on the lower surface but taper on the upper - this is correct...

That's about it for the moment, I'll finish off the webs tonight and then then make a start on the spoilers - should be fun..

LE sheeting and cap strips will follow then it will be almost time to cover it.

More to come..

M

Edited By Martyn K on 16/07/2014 15:49:40