DH 108 - This was the future - once. Interesting comparison with DH 110 added

[John R]

Originally designed as a half scale model of a planned jet airliner it became apparent during the design phase that the layout was unsuitable and but it continued as research a/c for investigating the characteristics of swept wings. Three were built. The first used a Vampire front fuselage and was used for low speed research. It crashed after spinning at low altitude. The second was used for high speed work but crashed whist practising for an attempt on the world speed record. The third, modelled here, had a modified fuselage having a more pointed nose and a lowered, more streamlined, canopy. It first flew in July 1947 and in September 1948 became the first British a/c to exceed the speed of sound, although completely out of control at the time!

It was passed to the RAE in November 1949 for further research but crashed in September 1950 for reasons unknown but believed to be pilot incapacitation due to lack of oxygen.

I once heard Eric Brown describe it as the most dangerous aircraft that he had flown.

 

This resin kit was produced by Planet models and went together fairly easily. There are three basic components, the upper and lower halves of the wing/fuselage and the rudder, all nicely moulded and free from pinholes. The most notable problem being the fit of the upper front fuselage – it doesn’t and requires filler to correct a large gap between the front portions ahead of the canopy. I realised later that I should have spent some time thinning the rear sections of the wing to produce a sharper trailing edge.

The kit is supplied with two vacform canopies. Unfortunately there is a flaw in that the frame which runs down the centre of the forward section is not quite in the centre. I had to trim the top of the pilot's seat to stop it fouling the canopy.. Not a big deal as it is hardly visible.

One final problem appeared whilst fitting the u/c. The a/c sits slightly nose up and the model does not. It is partly due to the mainwheels being oversize, compared to Barrie Hygates drawing, and something else which I could not work out. I ended up shortening the legs to get it to look right. In fact the original legs looked far too long to retract into the wells whereas the shorter legs look to be about the right length.

The finish is Alclad Airframe Aluminium over gloss black enamel followed by a light coat of Alclad Aluminium to reduce the shine.

 

John

 

 

 

 

Whilst putting it in the display cabinet I was reminded that I had seen that wing planform before...

 

 

I had always thought of the 108 as being small but, as a half-scale model of the proposed DH 106 it had a span of 39ft (about 12m)

Compare it with its American equivalent the Northrop X-4

 

[stevehnz]

That has come out really well, in spite of the hassles you had. If you can take a stinker of a kit & make it look that good, then my friend, you're a modeller. (To paraphrase Kipling) 

Steve.

[SAT69]

5 minutes ago, stevehnz said:

That has come out really well, in spite of the hassles you had. If you can take a stinker of a kit & make it look that good, then my friend, you're a modeller. (To paraphrase Kipling) 

Steve.

Totally agree!

[John R]

Thank you for the compliments but it's not a stinker by any stretch of the imagination. It went together fairly easily in a short time with a few hassles, not unexpected in a short run kit, and a few bits that you feel could have sorted out with more care at the design stage.

John

[F-32]

Very cool work, I'm not sure I've seen one of these finished before

[PHIL B]

Lovely model of a lovely looking aeroplane. From an age where proof of concept meant build it, fly it and see what happens.

 

Unfortunately the old adage "If it looks right etc." didn't apply. RIP Geoffrey de Havilland Jr, Sqn Lr Stuart Mullen-Rowland & Sqn Lr George Genders.

 

Phil

[Andrew.S]

Really nice model, I like it!

[Eric Mc]

A deadly beast - literally, all three crashed, all three killed their pilots.

 

But an important aeroplane all the same.

 

Your build looks really good.

[Andy Dyck]

Niiiiiiiice!!!!!!!!

[John R]

Some pictures added to the main thread showing comparsions with the DH 110 and the Northrop X-4

[Eric Mc]

I'm in the middle of working on a X-4. The X-4 was completely the opposite to the DH108. It exhibited pretty good flying characteristics and both examples survived their test programmes.

[Michael louey]

Hi John,

 

Thanks for putting this kit together to let us see how the DH108 looks. The plane is the central subject of the film "The sound barrier" where you get an idea of how dangerous this research was.

 

Regards

 

Michael

[John R]

I think that you are mistaken. The plane in question was the Supermarine 535 'Prometheus' of which there is no kit available, alas.

John

[John R]

On 8/26/2020 at 8:14 AM, Eric Mc said:

 The X-4 was completely the opposite to the DH108. It exhibited pretty good flying characteristics and both examples survived their test programmes.

Apparently the DH 108 was pleasant to so long as you stayed away from the extremes of its flight envelope. At the high speed end the X-4 apparently exhibited similar characteristics but as it flew much later than the 108 the pilots would have been aware of what to expect. I don't know if it ever went into the high mach/ high ias region that did for Geoffrey De Havilland but it was sensitive in pitch at high mach numbers.

John

[Michael louey]

On 8/29/2020 at 6:19 PM, John R said:

I think that you are mistaken. The plane in question was the Supermarine 535 'Prometheus' of which there is no kit available, alas.

John

Hi John,

 

Of course you're right - As soon as you mentioned it, the memory of the 535 returned (I think it's a Swift predecessor/prototype). I must have got the false memory from the era of the movie and perhaps the mention of the DH108 early in the movie - I'll get around to rewatch it to remind me of the story line.

 

Cheers

 

Michael

[kapam]

Very nice build!

Thanks for the brief history of the type too.  The test pilots of the burgeoning jet age were brave indeed to fly some of these prototypes. 😬

Nice job on the bright metallic finish.

👍👍

[Eric Mc]

23 hours ago, John R said:

Apparently the DH 108 was pleasant to so long as you stayed away from the extremes of its flight envelope. At the high speed end the X-4 apparently exhibited similar characteristics but as it flew much later than the 108 the pilots would have been aware of what to expect. I don't know if it ever went into the high mach/ high ias region that did for Geoffrey De Havilland but it was sensitive in pitch at high mach numbers.

John

I also think that Jack Northrop had a lot more experience with flying wings than tailless aircraft compared to de Havilland - which would have helped. Most tailless aeroplanes and flying wings exhibited some longtidunal issues - especially in pitch - until the advent of fly by wire.

[Graham Boak]

I suspect that's all, not just most.  However, longitudinal problems means in pitch.  Yaw problems are directional, and are also common on flying wings because of the short bodies and lack of a moment arm.  Roll problems are lateral.  Lateral and directional problems are often linked whereas pitch problems tend to have independent solutions.

 

Designers of flying wings under human control spent many hours trying to avoid the obvious solution to their problems - fit a tail!  After all, you aren't going to make your name as a forward-thinking genius if you keep coming up with the same solutions as everyone else.

[gingerbob]

A bit late, but nice to see one of these built, and especially nice to see the comparisons you've done!  Apparently DH chose the path Graham suggests above.

 

bob

[binbrook87]

That's just superb. I have a real soft spot for the British experimental aircraft from the 50s and your two examples are fantastic... great stuff!