Hi there, Whitley, I must aplogise for spreading duff gen ref de Havilland part numbers. I suppose it should be me that is now in hiding from the DH mafia. The early single numerical sequence of de Havilland drawings covered all types from the DH 60 to the DH 89 EXCEPT the DH 87.

For the DH 87 each part was designated by a three-digit prefix comprising a single digit followed by the Type number. The first digit was used to denote the location with the aircraft the part could be found. This system gave a much wider range of possible part numbers as the complexity of aircraft increased. The designation system for the DH 87 Hornet Moth followed this sequence:

187*** Fuselage
287*** Planes
387*** Electrics
487*** Empennage
587*** Undercarriage
687*** Engine installation
787*** Flying controls
887*** Instruments
987*** Miscellaneous

At a late stage of Dragon Rapide/Dominie development the drawing sequence 989*** was introduced for parts used mainly in the various radio fits applied to the aircraft.

For the DH 90 to 93 inclusive, the same numerical designation system as for the DH 87 was used; ie;

190*** + 191*** + 192*** + 193*** – fuselage parts for the respective type. In some cases a ‘zero’ designator was used (ie 091***) for general arrangement drawings etc.

With the DH 94 the same system of designating part numbers by the aircraft type and its location on the aircraft was used but instead of using a single digit prefix to the type number, a letter suffix was used. For example:

94A*** General
94C*** Controls
94E*** Engine installation
94******* Fuselage
94N*** Instruents/electrics
94P*** Petrol and oil
94T*** Tailplane
94U*** Undercarriage
94W*** Wings

This system then continued on subsequent aircraft types, with the letters after the type number being used more widely to discriminate between aircraft system; eg, on the Chipmunk:

C1-C******* Controls, flaps
C1-FS*** Fuselage, structure

As well as the type-specific drawing series, de Havilland used other generic designations:

DHA and DHS – used to denote de Havilland standard parts or processes applicable to more than one aircraft type.
J – used for standard material sections used across all types.
R – used for Repair drawings. For the early types using the original all-numeric drawing series the repair drawings were mixed up in a single R-series. Later models included R as a prefix to a number allocated in the normal drawing sequence; eg, from the Chipmunk RC1-FS*** would be a repair drawing for damage to the fuselage structure. As a slight complication, some repair drawings were prefixed RD – repair drawing – rather than R, as if the system was not complex enough already.

This is all very anally retentive, but I describe it in detail to illustrate how drawing designation systems changed even within a single company. Then there are the drawing systems of the SBAC and even the aerospace series of the British Standards Institute to consider, as well as the Inspector’s Stamp numbers that each of the companies operated.

This could be quite and interesting subject and it would be very useful to have some form of on-line database that carried this information. However, I suspect that this Forum is probably not quite the right place. Any suggestions, anyone?

It was not the norm for de Havilland to prefix part numbers with the letters DH. In the early years of Stag Lane design all drawings were numbered in a single numerical sequence. This covered types such as the DH 60 series, through to the Tiger Moth (DH 82) and Fox Moth (DH 83) etc. From memory, I think it was perhaps the Dragon (DH 84) which introduced a model designator in the drawing number but I would have to check if that is correct. Thus, the first element of the drawing (or part) number denoted the model, followed either by the drawing number or (for later types) a system designator and then a drawing number.

Thus, the configuration of de Havilland part numbers for the Chipmunk is C1-TP-313. This number denotes a Chipmunk part (C1) for the tailplane (TP). Other systems were denoted by letters such as CF (Controls, flap) and FS (fuselage, structure). Part numbers for the Dove and Devon start 104, the Heron 114, the Trident 121 etc. Strangely, de Havilland used to ‘pick and mix’ its parts and bits with Dove part numbers are still used on the Nimrod MRA4!

By the way, Whitley Project, the DH mafia gets terribly anal about the spelling of de Havilland – better not walk down any dark lanes for a week or two!

Canadair – I note your comments and agree that the homebuilt/experimental sector in North America is deregulated, bringing with it certain benefits; but there is a downside. If deregulation meant that only the designer/builder got killed when it all went wrong, then OK. Unfortunately, in the case of the Super Chipmunk a poor innocent passenger was also involved. I wonder how many times the PFA engineers (and perhaps those at the BMAA also, but I have no microlight experience) have prevented someone getting airborne in a home-designed aircraft which had a fundamental design flaw? The US system of total deregulation does not seem to have this long stop to weed out the crass mistakes.

You are right to say that certificated aircraft sometimes suffer structural failures and that maintenance in this sector is not always 100%. I agree. But when did you last hear of a Chipmunk having an airborne structural failure? Touch wood etc etc etc. The Chipmunk – at least the UK-built variant – has undergone a massive programme of structural testing funded by its principal customer, the RAF. The benefits of this testing have crossed over to the civil world and certain structural modifications were developed. Provided that these modifications are embodied at the due time (and provided that owners have properly recorded their fatigue hours!) then structural failure should not be an issue. I am not sure if the Canadian-built variants have the benefit of such testing as in many respects they are quite different aircraft to those buuilt in the UK.

I remain utterly convinced that you mess with proven designs at your peril. If you are going to go the homebuilt route then do it with an organisation like the PFA looking over your shoulder – they might just stop you killing yourself and some poor unsuspecting friend.

BUILDING A CHIPMUNK FROM SCRATCH ….!!***???

So you want to build a Chipmunk from scratch? Far better to buy one – they are cheap enough – and enjoy the excitement of owning and operating an iconic British aircraft, rather than a cheapskate homebuilt replica. Would you also homebuild a Gipsy Major engine to go with your homebuilt aircraft?

BADGES – NOT CRESTS

Sorry to nit-pick, but they are Badges, not crests! Big Vern has it all in his post of 24th June.

Pete

Congratulations on what you have achieved with the jet. Do you have names for the five venerable gents lined up beside the aircraft in one of the pics?

SMOOTH GRASS AT HULLAVINGTON – PERHAPS NOT!

Ozplane’s predictions of smooth grass as far as the eye can see for G-VFWE at Hullavington next year may not come to pass. I understand that during June 2006 the airfield at Hullavington is the venue for the Great British Tractor Challenge. This event is planned by the vintage tractor buffs to get together no less than 2006 tractors of all shapes and sizes, each coupled to a plough or some other cultivating implement. To set a world record for the most tractors and implements working in the same field at the same time, for inclusion in the Guiness Book of Records, all these tractors have to chugg around at the same time ploughing, cultivating, getting bogged down or whatever tractors do best. I hate to think what state the airfield will be left in – ruts, furrows and a mangled moonscape no doubt.

Do tell me I’ve got it wrong.

HENSTRIDGE SUPERFUELLER MOVED

Superfueller fans may wish to know that the Henstridge Superfueller was sold at auction on 19th May and was seen on a low-loader heading north up the A1(M) at Hatfield the following week.

Further research indicates the vehicle was a 1966 AEC Mammoth Major artic unit, known as a “Yorkshire” refueller and built by Thompson Bros of Bilston. The refuelling equipment (housed in the cabin to the rear of the cab) was manufactured by Zwicky of Slough. Owned by Shell, the Henstridge vehicle may have originated from Hurn and was complete when it arrived there. The 10,000 gallon trailer was subsequently sold and may have been exported to Africa.