Airspeed Courier

[Tim Hooper]

I'm probably a bit premature in starting this thread - I'm still in the plan-drawing/head scratching phase as yet - but let's give this a punt anyway!

 

Here's the history (as per Wikipedia);

 

"The Airspeed AS.5 Courier was a British six seat single engined light aircraft, production aircraft were built by Airspeed (1934) Limited at Portsmouth. It first flew on the 10 April 1933 and was the first British type with a retractable undercarriage to go into production, with a total of 16 built.

The prototype Courier was designed by Hessell Tiltman (co-founder of Airspeed Limited) and was built in 1932 by Airspeed at York for an attempt by Sir Alan Cobham to carry out a non-stop flight to India, using airborne refuelling. Airspeed moved from York to Portsmouth before the Courier G-ABXN first flew on 10 April 1933. The Courier was a wooden low-winged cabin monoplane, it had a novel feature for the day of a retractable undercarriage. The prototype being powered by an Armstrong Siddeley Lynx1933 at Portsmouth and in June 1933 at RAF Martlesham Heath. The aircraft was repaired on both occasions. engine. The prototype had two minor accidents, in April

After a year perfecting airborne refuelling, Alan Cobham took off from Portsmouth on the attempted flight to India on 24 September 1934, being refuelled from a Handley Page W.10 before force landing at Malta due to a broken throttle.

A production run of 15 Couriers followed, being used for air-racing (one finished sixth in the MacRobertson Air Race to Australia in 1934), and as a light airliner and air taxi.

In 1936 financial interests bought two Couriers with the intent to selling them for use in the Spanish Civil War. However, protests from the non-interference lobby in England stopped delivery. Two Republican sympathisers on the Airspeed staff made an abortive attempt to steal G-ACVA. One of them, Arthur Gargett, died in the attempt; the other, Joseph Smith, was sentenced to four months in prison.

Owing to its advanced aerodynamics, two were used as research aircraft, one by the Royal Aircraft Establishment and one by Napier's, who used it for development of the Napier Rapier engine.

At the outbreak of the Second World War, the majority of the surviving Couriers were impressed into the RAF, who used them for communications purposes. Only one Courier survived the War, being used for joyriding at Southend-on-Sea before being scapped in December 1947.

General characteristics

• Crew: 1
• Capacity: 5
• Length: 28 ft 6 in (8.70 m)
• Wingspan: 47 ft 0 in (14.33 m)
• Height: 8 ft 9 in (2.68 m)
• Wing area: 250 ft² (23 m²
• Empty weight: 2,344 lb (1,065 kg)
• Loaded weight: 3,900 lb (1,770 kg)
• Powerplant: 1× Armstrong Siddeley Lynx IVC radial piston engine, 240 hp (179 kW)

Performance

• Maximum speed: 133 knots

[Tim Hooper]

I've found an approximate 3-view and a few photos on the net - more than enough to allow me to start drawing up a 56" model.  That equates to around 1/10 scale.

 

 

 

 

 

 

Edited By Tim Hooper on 26/09/2010 19:44:06

[Tim Hooper]

So I dug out the crayons and made a tentative start........

Apart from all the glazing, the fuselage looks to be reasonably straighforward.  A lower box is topped with a tapering-section roof.  The tail surfaces are simple frameworks.

The wing is a little more complex.  I've plumped for a semi-symmetrical Clarke YM15 aerofoil (courtesy of Profili).  The centre section is flanked by outboard panels that feature both dihedral and washout.

Oh, did I mention that it's going to have a retracting undercarriage?

 

This is likely to be quite a slow-moving build, but I'm almost ready to start cutting balsa....

 

tim

 

[Andy Harris]

TIm

 

 I've got some of those retracts, I thought they'd replace the the less than effecttive round the house linkages on a BH Mosquito.

 

 Having tested them I wonder if they are strong enough.

 

Regards

 

 

Andy 

[Tim Hooper]

Hi Andy,

 

These are the 15-25 sized units - allegedly good for a 7lb model.  I emailed E-Flite to see if they'd be suitable for a rearwards retracting application, and they gave me the OK.

 

Further searches on another forum bore that out;

 

F5 Tigercat Maiden by Merlin v16 from Fred Sgrosso on Vimeo.

 

tim

 

[Andy Harris]

Cheers Tim

 

  I found I could stop them with just light finger pressure.  I have the 15-25 ones as well.  I've been testing them with a Turnigy servo tester.

 

  My Mossie is 2.5Kg so at 7lbs I should be in ... 

 

 They are too short for the Mossie, but I'm hatching a cunning plan to extend them and make them look a little better at the same time. 

 

...Andy 

[Tim Hooper]

Ooooops! Double post.....

Edited By Tim Hooper on 27/09/2010 10:30:07

[Tim Hooper]

Posted by Andy Harris on 26/09/2010 22:04:08:

 

  I found I could stop them with just light finger pressure.  I have the 15-25 ones as well.  I've been testing them with a Turnigy servo tester.

 

...Andy 

 Andy,

 

If you watch the promo video from E-Flite you'll see that they're designed to stop mid-travel very easily to prevent damage to either servo of airframe, but can be re-set by flicking the switch on the tx again.

 

Lemme find the link.......

 

http://www.youtube.com/watch?v=N_s0vFIvfjo&feature=player_embedded 

 

 

tim

[Tim Hooper]

A little more progress.................

 

Checking the retract unit in-situ.  The leg will have to bent in two places to clear the lower spar.  What could possibly go wrong?

I've traced the rib templates onto tracing paper, sprayed some 1/16" balsa sheet with glue, and stuck the templates in place.  The next couple of hours were spent in cutting them out!

 

tim

 

[Erfolg]

Tim

 

Are you using Profi, or similar software for the Wing ribs.

 

Personally there is only one thing i dislike doing and that is cutting out wing ribs. I have been delaying cutting out a set for latest build all morning. Sad.

 

I have never appreciated any Airspeed aircraft, as they all seemed ugly, excepting the one you seem to have found. Actually I think there is one more that looks really good Elizabethan/Ambassador? 

 

Any way it looks really good and an excellent thread. Perhaps the RCM&E build articles could draw on the presentational style to provide variation. Rather than the stylised formulaic, almost Lab-work approach. 

[Tim Hooper]

Erf,

 

Yes, I'm using Profili.  I don't have the 'pro' version otherwise I could just print out a complete wingplan complete with spars, sheeting, et al.  I sort of work in fits and starts and, like yourself it seems, tend to find reasons not to do certain tasksput them off any longer!  No matter - it all gets done in the end!

 

There's 29 ribs in total.  The tapered wing means that there's 14 pairs, and a central rib.  How anoraky is that?

 

 tim

[Erfolg]

Tim

 

It is perhaps worth mentioning the "boon" of aerofoil software, such as Profi, in your next RCM&E article. These programmes make quick work of what was a time consuming and dare I say boring process. That allows all model makers easily produce their own designed wings.

 

I to us the basic package, as if I produce 3 new wings a year to my own design, it is probably a good year.

 

Reading about you going to cut your wing ribs, inspired, shamed me? into doing my own.

 

 

 

[Danny Fenton]

Hi Tim, lovely build as usual, only just spotted it sorry about that. I have done the odd design, but have always made sure I have a few fus sections on the drawings. How have you decided the fus bulkhead shapes from only one nose on shot? Is it a case of if it looks right then it is

 

Cheers

Danny

[David Turner 5]

I'm interested in this build, because the Courier is one of those machines that I'd like to model, before I snuff it.

 

I have the plan ... can't recall the designer - Vaughan? ... but am put off by the fierce taper to the wing.

 

I've run it through Profili Pro, using what I believe to be the appropriate wing sections, and it all checks out OK. Still, there's that nagging doubt.

 

The Stuka is another one - like to build one, but just a bit concerned about its docility. There's likely a good reason why they are so rarely seen.  It'll be interesting to see the Blackhorse' version at work.

 

Fact is, I've never seen a Courier modelled and flown, though I did speak to an LMA chap who has a large-ish version. He wasn't too forthcoming with the nitty gritty of the wing' geometry, though.

 

Oh, yes, and it's crying out for flaps. It's really a powered glider, I suppose. All terribly efficient, but a pig to land accurately, I would judge.

[Tim Hooper]

Gents,

 

To try and answer your questions.......

Danny, I haven't managed to find any fuselage sections so, as you've guessed, I've taken a stab at what I think won't look too bad (and will be easy to build - basically a rectangular box below the waistline, with a tapering superstructure on top.

At the wing LE.

 

At the wing LE.   Simple, huh?

 

David,  I've plumped for a basic Clarke YM15% for all the ribs, but i'll be building in a degree or two of washout in the outboard panels.  AS you say, this is basically a powered glider so I'm hoping that a low wing loading will imbue the Courier with a forgiving nature. We'll see.

 

Right th, I finally managed to get the spars and a couple of ribs glued over the plan this evening, so construction has actually started!   Having said that, ther'll now be a short intermission as we're off to the Lake District for a few days!

 

tim

Edited By Tim Hooper on 02/10/2010 22:43:53

[Danny Fenton]

Thx Tim, have a good break, and hope the weather behaves

 

Cheers

Danny

[Tim Hooper]

Hiya Danny!

 

We're back, and had a great time.  Yes, we had some rain, but on the other hand, we had some lovely sunshine too!

 

So.................it's been back to the building board...........

The basic outline, and a few ribs in place.

The centre ply brace is necessary because of the sweptback spars.

I used a square to trim the front of the ribs prior to fitting the leading edge.

 

 

tim

[Tim Hooper]

So take one perfectly servicable wing.....

....and cut it into three pieces!

A good days work, I'm sure you'll agree.

 

tim

 

[Tim Hooper]

With the wing panels re-joined at the requisite dihedral, and with R4 and R5 doubled-up with 1/16th ply, I fitted 1/8 ply mount plates for the retract units.

 

It was then a case of bending the wire legs to clear the spar, and cutting wells in the lower centresection skins to allow the wheels to retracf.

 

Seems to work OK!

 

tim

The wheels they go up....

...and the whells they go down!

[Stephen Grigg]

Tim, how do you get the strength into the retract mounts so lacking in  many ARTF it seems,and could you teach the ARTF manufacturers a  lesson in this area?

[Tim Hooper]

Stephen,

 

I'm no expert when it comes to fitting retracts (or anything else for that matter), but it always seems to be a bit of a compromise trying to juggle not only strength and weight, but also whether it's desirable to actually build in some kind of weakpoint, which will break away from the model without tearing out half of the surrounding area!

 

What I've done is to fit 1/16 ply doublers to the fronts of the ribs either side of the retract unit to give a rigid base to start with.  The 1/8 ply mounts themselves are PVA'd in place (with a little balsa reinforcement).  Hopefully this'll be strong enough, but will break away in the event of an emergency, with wrecking the mainspar.

 

Basically it's all guesswork!

 

tim

 

 

[Tim Hooper]

Just for a bit of light relief I've salvaged some 3/16 strip from the scraps box, and cobbled together the tail surfaces.

....and then it's back to the wing to tackle the top sheeting.  The tips are raised on little blocks of balsa that are profiled to include 3mm washout at the trailing edge.

 

[Tim Hooper]

With the centre-section pinned flat on the board, the shaped washout/dihedral jigs are temporarily glued to the underside of the tip ribs before adding the 1/16 shear webs and 1/32 upper skins.  This 'locks in' the required washout.

Moving on to the fuselage, the lower sides are cut from 1/8 sheet, and are fitted with wing doublers and longerons, before adding F2 and F3.  Exciting stuff, huh?

 

tim

[Simon Chaddock]

Very neat Tim.

Good old conventional building.

it should look superb.

[Tim Hooper]

Thanks Simon!

 

I've nothing against foam, composites or ARTFs in general - in fact I fly all of them regularly.  Having said that, they really can't match the satisfaction I derive from fettling itty bitty bit of balsa wood!

Anyway the fuselage is well underway now .....

The lower sides meet F2 and F3.

Assembled together.  The large cutouts in the formers allow space for the battery pack.

 

Pinned upside down, the front ends of the fuselage are repeatedly sprayed with water whilst being gradually drawn in together.  A few judicious saw cuts in the longerons eased the process considerably.

 

As the top of the fuselage sides lie at 5° to the datum, and as there's no downthrust used, I made up this little gauge to place F1 accurately.

 

tim

 

Edited By Tim Hooper on 26/10/2010 11:20:53