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Biplane rigging wires

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Gerry Stansfield17/09/2008 15:47:00
36 forum posts
9 photos

   Can enyone tell me why the rigging wires on some Bipes are crossed over as [Tiger Moth] where as on th D.H.60 the wire run parallel?.

Eric Bray17/09/2008 17:33:00
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6600 forum posts
2 photos
The basic reason is structural strength. a triangle is more rigid than a rectangle!
Gerry Stansfield17/09/2008 19:50:00
36 forum posts
9 photos
 Thanks, Eric,  for info: the reason I asked about cross over wires is I have a Tiger Moth which has the wires crossed over, but I am building a D.H.60 Moth the same size,[1/4 scale] but all the info I have on it  the wires run parallel, as you say a triangle is more rigid than a rectangle, so crossed over they will be. Thanks again.
Bob Cotsford18/09/2008 11:42:00
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4312 forum posts
224 photos

just a guess, but as the Tiger, like the Bucker bipes, has sweepback, I would say that it uses landing and flying wires in a V shape in order to use the top rear cabane strut as a mounting for the landing wires and the front lower spar for the flying wires. This way the triangle formed in plan view is more evenly balanced for the relevant wing so that as  well as vertical forces, the V braces the wing against fore and aft forces.  take a look at

tiggie

 and

Moth

The DH 60 has noticably less stagger, so the parallel rigging in plan view can be used without a tendancy to pull the lower wingtips forward and the upper backards.

Gerry Stansfield19/09/2008 00:19:00
36 forum posts
9 photos
 The rigging wires on the D.H 60 are actually mounted at the wing roots, not on the fuzzy; which makes it unecessary to remove them when folding the wings.they are hinged at the trailing edge and a locking pin is inserted into a fixture on the side of the fuzzy; holding them in place, ive managed to do that  with mine after a lot of [head scratching]
Simon Chaddock19/09/2008 00:32:00
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3621 forum posts
1836 photos

The Moth (and Gipsy Moth) could have their wings folded along the fuselage (a jury strut was required at the front wing spar joint to keep the wings rigid when folded) but the Tiger Moth wings do not fold as the rear spar bolts are not in line due to the wing stagger. The Tiger was designed to a military spec and wing folding was not included.

There is this picture of Belgian surplus Tigers with their wings folded back but the concensus is that they were being stored prior to scrapping so the damage to their rear spar mountings did not matter!

Gary Binnie05/10/2008 16:25:00
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428 forum posts
23 photos

Interesting thread, I part-own, maintain and fly a full size Tiger Moth as well as building flying models of them (have a look in my gallery). On the Flair 1/4 scale Tiger the wires are functional (silver soldered).

The flying and landing wires on the Tiger actually attach to the wing root ribs, this is a left-over from the earlier Moths with folding wings. I had a close look at a DH60 'Gipsy' Moth recently and was intrigued to see that de Havilland used the same wing fittings!  The quick release pins are replaced with a more permanent pin but the rear hinge points (upper and lower) are still there. As Simon says the wing assemblies can not be folded because of the geometry.

I've got some close up photos of the fittings if anyone is interested.

Often think about those wires when I'm floating along, they do have to be checked and looked after regularly.

Cheers

Gary 

Gerry Stansfield03/11/2008 12:00:00
36 forum posts
9 photos

 Hi, Gary. I would very much like to see your photo's of the wing fixing fittings of the Moth, to compare them with the one's I have made for mine, I have lots of pictures of the DH60 but no close ups of the actual fixings, I only hope mine are strong enough for the job!!  The flying wires are fully functional and running parallel to each other, unlike the Tiggy which are crossed, as you will know, part owning one [lucky you], always fancied a fly in on, have to make do with the model! Kind regards, Gerry.

Gary Binnie03/11/2008 15:46:00
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428 forum posts
23 photos

Hi Gerry,

They are not as close up as I remember but I can take some more if you need them.

1. Lower wing rear hinge fitting and flying wire attachment:

http://www.modelflying.co.uk/sites/3/images/member_albums/27615/Copy_of_100_1089_0.JPG

2. Upper wing rear hinge fitting, vertical pins at each end of the tube behind the fuel tank.
http://www.modelflying.co.uk/sites/3/images/member_albums/27615/Copy_of_100_1082.JPG

3. General view of the wires:
http://www.modelflying.co.uk/sites/3/images/member_albums/27615/Copy_of_100_0931.JPG


Have not flown for a while (Tiger or models), weather is a lottery this time of year!

Cheers

Gary

Simon Chaddock03/11/2008 23:11:00
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3621 forum posts
1836 photos

Gary

Nice pictures.

It always amazes me just how tiny all the fittings are and they take ALL the flying loads. As you say it a good idea to check them once in a while when that is all thats keeping you flying!

Gerry Stansfield04/11/2008 11:29:00
36 forum posts
9 photos
 Gary,  If you can take some closeups of the rear hinges top and bottom an one of the locking pins I would really appreciate it, thank's,  Agree with you about the Weather.
Gary Binnie04/11/2008 15:33:00
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428 forum posts
23 photos

Yes, it is a bit 'thought provoking'  when you see what holds it all together, an incentive to do good pre-flight inspections and go easy on the 'G' forces.

Will do Gerry, won't be for a little while though (Sqn reunion this weekend and a visit to Duxford, never been).

Cheers

Gary 

Steve biplane05/11/2008 17:48:00
85 forum posts

The Tiger Moth introduced the staggered wing and change of rigging geometry as a result of the RAF's requirement that the front seat occupant can bail out as easily as the rear. The staggered wing allowed the centre-section wing struts to be moved ahead of the front cockpit. Both the lift and landing wires run to the forward spar position (at the fuselage) so as not to be in the way of the bale-out. 

 I'd be interested to hear Gary's thoughts of the difference/similarities of flying full size and large, quarter scale model Tigers.

 Steve 

Gary Binnie05/11/2008 19:19:00
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428 forum posts
23 photos

Almost!

The centre section (cabane struts) went forward for the reason you describe ( a hacksaw and a cigarette packet drawing were involved allegedly!) then the wings had to be swept back to preserve CofG and centre of pressure (lift) relationship.

With the tail down this moved the lower rear wing tips quite close to the ground and they often touched on the prototype Tiger during taxiing, the answer was more dihedral on the lower wings (leaving the upper wings untouched) to give more clearance, achieved with a hacksaw again to shorten the interplane struts!

The sweepback angle is slightly different on upper and lower wings and another 'fudge' left over from the redesign is that the wing ribs are in line with the leading edge and not the airflow. I've got a KeilKraft plan from the 1950's that has them in line (and a rolled up balsa cement tube shown for nose ballast, remember those tubes?!!)

Comparison between models and full size? Quite similar I think, both are very stable in flight and not particularly aerobatic. The full size controls are quite heavy in feel (especially compared to a Chipmunk) . The full size stall is quite benign with the slats out (about 35 knots) but with the slats in it is quite different and will drop a wing and spin quite rapidly if not recovered. Some Tiger's don't have slats (or anti-spin strakes) of course. Rudder needs to be used on both, I usually mix it in with the ailerons on a model.

Approaching the stall there is virtually no 'pre-stall buffet' warning which I found quite 'interesting' when I converted to the Tiger Moth, it might be the reason that quite a few have met the ground over the years with the pilot usually walking away wondering what happened! I always watch the airspeed very carefully near the ground, being 'draggy' it is quite easy to slow down without noticing.

I think we fly TM models with a slightly forward CofG from the full size position for pitch stability, most of my Tiger models (I think I had five of different sizes at one stage) were very reluctant to stall or spin.

This Flair Tiger is very stable but a bit underpowered with an OS FS120, it originally had 2 lbs of lead in the nose, I gradually removed some (but not much) until it would just spin with the right 'provocation'.

It has working flying and landing wires which have silver soldered end fittings (standard metal RC servo clevises for adjustment).

Sorry about the ugly bloke!

Cheers

Gary

http://www.modelflying.co.uk/sites/3/images/member_albums/27615/Tiger_Moth_Canon.jpg

This one was an experiment (rubber free-flight to GWS electric power and radio control conversion), suffered from 'glitching' interference and it is in semi-retirement (thought I'd better before it met a sticky end!)

http://www.modelflying.co.uk/sites/3/images/member_albums/27615/100_1124.JPG

Steve biplane05/11/2008 19:55:00
85 forum posts

Gary, Thanks for your quick reply and interesting comments re full-size and model Tigers. I've only managed to have one Tiger flight - that came as a complete surprise and was due to winning a raffle at Shuttleworth's several years ago. Best memory from the flight was turning at Cardington and seeing the airship sheds below. I'll be making a DB Tiger Moth over the winter (1/6th size) so it will be interesting to see how it goes together and flies.

Steve 

Gary Binnie05/11/2008 21:56:00
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428 forum posts
23 photos

Old Warden is a very special place for me, been a visitor since the late 1960's. My dad was a regular on the free flight days, I met fantastic people like Ron Moulton, Howard Boys (a real character), 'Jack' Frost, John Blagg (superb peanut scale), Mick Staples (excellent control line scale builder and flyer) and many others.

I have some old cine film of RC Spitfires and a Beaufighter taking off (or trying to) on hardboard runways, there is also a Jet Provost formation team of four aircraft in silver which might date it. 

Been over in the Tiger a couple of times this year and always feel guilty for temporarily stopping the modellers from flying! Always get a cheery wave though.

I have a very distant memory of a pub near Cardington with a ride-on steam railway in the garden, possibly called 'the fox and hounds', does this ring any bells with anyone? 

Good luck with the DB build, I hope you are going to post a build thread.

Cheers

Gary 

gerald stansfield08/10/2009 15:36:38
24 forum posts
10 photos

Spread your wings, and Fly.
Ady Hayward09/10/2009 14:43:47
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557 forum posts
692 photos

Hi,
Just a little point. The prop on the Gypsy engine rotates opposite to the model engine and most "Spam Cans". My first attempt at taking off in a Tiger (G-ANEF) was a bit of a weaving line ahead having lead the power application with right rudder and not left!. Re- starting the engine in flight is an occasion too, haviing to push past the vertical to get enough airspeed to turn the prop over......AAAH happy days.
 
Regards
 
Adrian
Simon Chaddock09/10/2009 23:16:19
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3621 forum posts
1836 photos
Adrian
A good point - I wonder how many scale Gipsy engine types have the prop going round the right way. 

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