Revell Lancaster

[Miggers]

I'm curious as to how measurements from photos of the real thing are so glibly ignored, and a single book figure is taken as the gospel truth instead.

It's clearly an angle that will vary with loading; same as height of an aircraft will vary with payload due to varying oleo depression. I'm all for accuracy but doggedly hanging on to a single number when it's a measurement that covers a range in reality is being a bit blinkered.

Bang on Damien.

Bill,whatever comes out over this dihedral debate(again!!),the bottom line is that the Revell Lanc makes a pretty decent model of the old girl with plenty of detail to boot and,and it's half the price of the overblown Hasegawa attempt(which was also ripped to bits by those in "the know").

As I've already stated,I reckon the dihedral is about right for an unloaded wing.

Mark

[Barracudadude]

I don't think anybody has been trying to do that here, although some of us have commented on what we see and interpret from photographic evidence. From my own meagre instruction in engineering I would deduce that the outer panel is a pin jointed cantilever that would deflect according to how it is loaded. That might be static load whilst the A/C is at rest on the ground and would include self weight plus superimposed loads from fuel etc, in which case the panel might droop. Or dynamic load whilst the A/C is in motion, in which case the panel dihedral might increase. OTOH, seeing as I have no training in aircraft structures I could be barking up the wrong tree completely, but my reaction is still my perception from looking at different photos of Lancs at rest and in motion - and I have quite a few to choose from in my own little library.

I'm not particularly anxious to defend the Revell kit, although I think some of the criticism in this respect is a bit harsh, but I am pretty keen to get to the bottom of the whys and wherefores of the dynamics of the Lanc wing structure. I think it was the description of Sqdn Ldr Calder's (?) A/C in Brickhill's 'The Dambusters' that got me started down this route.

peebeep

I have not seen any true-head on view photographs of the Lanc on the ground. Remember that parrallax error can have a serious effect of geometry. The photo shown above is not even close to being a true head-on view, so is not useful for determining angles.

I am pretty sure that the dihedral break is not designed to flex or pivot a number of degrees due to wing loading. It seems to me that the wing skins would be buckled or ripped apart. A wing needs to be rigid. It will of course flex under load, but this is distributed along the whole span, of course more concentrated the further outboard you go. Anyone having flown in airliners in rough weather knows how much they can flex! It can be downright disconcerting. But its very clear to see that the flex occurs along the entire span.

So, are we saying that the noted British Aviation Draughtsman Alfred Grainger and Airfix and Hasegawa all didn't do a very good job when it comes to the correct dihedral for the Lancaster? Should the Airfix wings be cut and the dihedral reduced to be accurate? Given that there are a number of other accuracy issues with the Revell kit, isn't it possible that they got the dihedral a little understated?

Roy

[Smiffy]

These are the closest I have to a head on view.

[Miggers]

Let's look at it another way.

AFAIK,the Revell people used Hendon's example for their information.

How many ops had R5868 done before she was tour expired(100+)?how many of those ops would have been done at MTOW and even beyond?

Although it was common practice to de-bomb an aircraft if an op had been scrubbed a couple of times over a few days to give the oleos some respite,

were the aircraft de-fuelled??how many times were they left with a full fuel load onboard?

Health and Safety weren't so prevalent back then,so if a spar failed in flight,would there have been many survivors of the accident to point the finger??

By the time she was tour expired with that number of ops she was a very,very,very old Lanc indeed,so how many cycles of flex and re-flex,re-fuelling ,erks clambering all over it,engines removed and refitted would her wing have gone through?

Has she been re-sparred since tour expiry and has she been re-sparred again by Hendon??

How many other "Ton-up"Lancs are there surviving for us to compare to R5868?(none)

Do you see where I'm going here Roy?

R5868's wing is obviously in good enough shape for static display,but for flight it'd be very suspect indeed.

So is it possible that,considering the number of flex and re-flex cycles it must have been through,the number of times it was operated at MTOW and even overloaded,the number of times it was left standing with a full load of petrol in it's tanks,that the mainspar and the rest of the structure have "settled" slightly?

If the wing can flex upward under load then surely it's possible for it to "sag"slightly over time under it's own structural and engine weight?

The main question here is this:

If Revell used R5868 as their master so to speak,and given the possible amount of "wear and tear" on '5868's wing,have they given us a representation of a well worn,well overloaded,well flown wing as they've seen on R5868?

If so then they've done something that other manufacturers haven't done and that is to give us a copy of a high time wing,enabling us to model a high time Lanc,so hence I say that it looks about right for an unloaded wing.

PA474 is extremely well monitored(even having a fatigue meter fitted)for "wear and tear".

I bet that Airfix crawled all over PA474 when they did theirs in the late 1970's by which time she'd been "majored"and re-sparred.

Whose did Hasegawa crawl over??if it was PA474 then there you go.

Mark

Edited November 30, 2008 by Miggers

[Heraldcoupe]

I bet that Airfix crawled all over PA474 when they did theirs in the late 1970's by which time she'd been "majored"and re-sparred.

PA474 was re-sparred in the winter of 1995-6. According to what was reported at the time, this was the first instance of a Lancaster being re-sparred, which means that whichever Lancaster was measured by Airfix, it would have been on it's original spar,

Cheers,

Bill.

[DHP]

Let's look at it another way.

AFAIK,the Revell people used Hendon's example for their information.

How many ops had R5868 done before she was tour expired(100+)?how many of those ops would have been done at MTOW and even beyond?

Although it was common practice to de-bomb an aircraft if an op had been scrubbed a couple of times over a few days to give the oleos some respite,

were the aircraft de-fuelled??how many times were they left with a full fuel load onboard?

Health and Safety weren't so prevalent back then,so if a spar failed in flight,would there have been many survivors of the accident to point the finger??

By the time she was tour expired with that number of ops she was a very,very,very old Lanc indeed,so how many cycles of flex and re-flex,re-fuelling ,erks clambering all over it,engines removed and refitted would her wing have gone through?

Has she been re-sparred since tour expiry and has she been re-sparred again by Hendon??

How many other "Ton-up"Lancs are there surviving for us to compare to R5868?(none)

Do you see where I'm going here Roy?

R5868's wing is obviously in good enough shape for static display,but for flight it'd be very suspect indeed.

So is it possible that,considering the number of flex and re-flex cycles it must have been through,the number of times it was operated at MTOW and even overloaded,the number of times it was left standing with a full load of petrol in it's tanks,that the mainspar and the rest of the structure have "settled" slightly?

If the wing can flex upward under load then surely it's possible for it to "sag"slightly over time under it's own structural and engine weight?

The main question here is this:

If Revell used R5868 as their master so to speak,and given the possible amount of "wear and tear" on '5868's wing,have they given us a representation of a well worn,well overloaded,well flown wing as they've seen on R5868?

If so then they've done something that other manufacturers haven't done and that is to give us a copy of a high time wing,enabling us to model a high time Lanc,so hence I say that it looks about right for an unloaded wing.

PA474 is extremely well monitored(even having a fatigue meter fitted)for "wear and tear".

I bet that Airfix crawled all over PA474 when they did theirs in the late 1970's by which time she'd been "majored"and re-sparred.

Whose did Hasegawa crawl over??if it was PA474 then there you go.

Mark

[DHP]

Let's look at it another way.

AFAIK,the Revell people used Hendon's example for their information.

How many ops had R5868 done before she was tour expired(100+)?how many of those ops would have been done at MTOW and even beyond?

Although it was common practice to de-bomb an aircraft if an op had been scrubbed a couple of times over a few days to give the oleos some respite,

were the aircraft de-fuelled??how many times were they left with a full fuel load onboard?

Health and Safety weren't so prevalent back then,so if a spar failed in flight,would there have been many survivors of the accident to point the finger??

By the time she was tour expired with that number of ops she was a very,very,very old Lanc indeed,so how many cycles of flex and re-flex,re-fuelling ,erks clambering all over it,engines removed and refitted would her wing have gone through?

Has she been re-sparred since tour expiry and has she been re-sparred again by Hendon??

How many other "Ton-up"Lancs are there surviving for us to compare to R5868?(none)

Do you see where I'm going here Roy?

OK, this is going nowhere. Whatever excuse you and others try to come up with, the Air Publication for the Lancaster, admittedly a Mark 10, says that the dihedral on the outboard wing was 7 degrees along the datum. Since these Canadian Lancs were parts interchangeable with the UK built ones, as far as I am concerned...and I worked and flew in them briefly (Dam Busters movie) anything less than seven degrees is not right. Ergo, the Revel Lancaster has, as they say in the Exited States, didn't do a very good job.

Cheers,

Derek

R5868's wing is obviously in good enough shape for static display,but for flight it'd be very suspect indeed.

So is it possible that,considering the number of flex and re-flex cycles it must have been through,the number of times it was operated at MTOW and even overloaded,the number of times it was left standing with a full load of petrol in it's tanks,that the mainspar and the rest of the structure have "settled" slightly?

If the wing can flex upward under load then surely it's possible for it to "sag"slightly over time under it's own structural and engine weight?

The main question here is this:

If Revell used R5868 as their master so to speak,and given the possible amount of "wear and tear" on '5868's wing,have they given us a representation of a well worn,well overloaded,well flown wing as they've seen on R5868?

If so then they've done something that other manufacturers haven't done and that is to give us a copy of a high time wing,enabling us to model a high time Lanc,so hence I say that it looks about right for an unloaded wing.

PA474 is extremely well monitored(even having a fatigue meter fitted)for "wear and tear".

I bet that Airfix crawled all over PA474 when they did theirs in the late 1970's by which time she'd been "majored"and re-sparred.

Whose did Hasegawa crawl over??if it was PA474 then there you go.

Mark

[Dave Gibson]

So, are we saying that the noted British Aviation Draughtsman Alfred Grainger and Airfix and Hasegawa all didn't do a very good job when it comes to the correct dihedral for the Lancaster? Should the Airfix wings be cut and the dihedral reduced to be accurate? Given that there are a number of other accuracy issues with the Revell kit, isn't it possible that they got the dihedral a little understated?

Roy

Hi Roy,

I'm glad I can keep out of this as the only Lancs I possess are 1/48. They have their problems too. But that's a different story and I don't want to hi-jack the thread.

Regards,

Dave.

[AnonymousA667]

So, are we saying .... Airfix and Hasegawa all didn't do a very good job when it comes to the correct dihedral for the Lancaster? Should the Airfix wings be cut and the dihedral reduced to be accurate? Given that there are a number of other accuracy issues with the Revell kit, isn't it possible that they got the dihedral a little understated?

I'll not get drawn on scale drawings, I have a view but it's irrelevant here. Hasegawa wing pictured in the middle below. Looks very perky to me and there are other well publicised issues with this kit. The Revell wing looks too flat - which I have said before - but interestingly if you compare the angles between the joints of lower and upper halves it is not that different to the Airfix, so maybe it is actually the taper that isn't quite right? I still stand by my belief that some droop occurs at rest with respect to self and superimposed loads and that the quoted rigging angle is for a jigged up wing, so the amount of correction would depend on what you see with your own eye from observation of real or photographed machines.

I still regard the Airfix kit as the best all round package, although it looks a tad expensive compared to the Revell and detail sets to dress it up are not cheap. As well as the wing fix the Revell kit requires all the wheels to be replaced and the mid-upper turret looks a bit large - or maybe it just sits too high on the fuselage.

peebeep

[chadders]

As a modeller who has built countess Lancs, but one who does not profess to being an aviation engineer, I can catagoricly say that Revell has got the Lancaster closest to any PRESERVED example to date. The Hasagawa kit is wrong in a number of areas (putting the canopy escape hatch was probabley the most silly, basic mistake, by a kit manufacturer in recent times) and the wing dyhedral is wrong for a Lanc at rest, the Airfix kit ( a kit that I hold dear to my heart, and one that I will probably build many times in the future), has issues reguarding options (like not being able to model unshrouded exhausts without surgery),while the Revell kit goes together well and looks right (if you think the upper turret is too tall, test fit and amend accordingly like modellers used to do!).

I'll put this another way. When you look at a Revell Lancaster built up on a club stand do you look at it and see Thunderbird 2!. No, you look at it and see a a new mold Lancaster. Something modellers have been wanting for years. I think it looks right, I think it builds right. I have 14 Revell Lancs in my stash, as they are the best available. Out of the available 1:72nd Lancasters I feel the Revell Lancaster are the best options.They are not without their faults, but the overall faults on the Revell issues are easier to correct than those on either the Hasagawa or Airfix kits

Mark

[John B (Sc)]

It seems fairly clear. The main and outer wing sections were both set at 7 degrees wrt datum. I'd accept Francis Mason's reading of the specs rather than any number of pictures. Mr Mason was a senior designer for Hawker, so I reckon his figures can be taken as likely to be accurate! Yes, taken from one book, the aircraft rigging manual. As an engineer that is the only final authority I'd accept. The Lincoln is quoted as having the same settings.

Regardless of loadings, overloadings, ageing etc., any aircraft which when dimensionally checked was out of true tolerances would have been withdrawn for check, overhaul and repair as appropriate before flying again. I expect if we were to ask the BBMF ground crew, they will know in which attitude and configuration the dihedral requires checking. Generally this will require the unloaded aircraft to be trestled to a level fuselage datum position. The wings would also be trestled - stencils were applied for this purpose. As peebeep says, the dihedral measurement could tahen be assessed, while trestled.. And it is wrt datum, which will be shown on the aircraft rigging drawings, or defined precisely in the rigging manuals. So checking the apparent dihedral from photos of the BBMF machine on the ground, while fun, won't help at all. Angular assessment (from what reference?) is not possible at all and loading state etc. is not known.

Note that it would also have been necessary to specify where on the wing that value was taken – the wing tapers in frontal view and in plan. It also has washout built in. Aaargh - a complex 3D shape. A value may have been taken using the mainspar line along the undersurface of the eing, or a value taken to a specified point on a particular rib. It's not an easy exercise, requires some rigour and precision - which is why aircraft riggers & maintainers sometimes get tetchy.

I expect dihedral settings will be one of the items checked typically at each Cof A - every three years? Alternately it may only be a check done if there are any reported oddities in the handling. Also any significant change should be visible to the crew on general inspection.

That said, what miggers (Mark) says is entirely fair - the aircraft now at Hendon has been out of service for a long time. It will have been left loaded, and overloaded frequently, it presumably has also been dismantled and reassembled a number of times since it was last checked and approved for flight - I presume the outer panels can be removed ~readily? How much allowance for rigging adjustment is there? Its long ground period may well have resulted in further sagging of an aged and probably somewhat corroded structure.

In flight I'd expect the flexing to be several degrees normally and a darn sight more at max overload. Aircraft wings flex much more than people think - I recall watching a Boeing 707 as we went through a thunderstorm. Very impressive. A glance at any photos of max load tests will show astonishing flex before break. I believe the Boeing manual quoted a max tip upwards deflection of around ten feet from the unloaded ground 'datum' before failure. That was a long time ago and I don't have the manual to check. (As someone else said they had better flex. Rigid is not good.)

Of course if you want to see serious wing flexing in flight have a look at modern glassfibre or carbonfibre sparred sailplanes. Wow.

Mark - nice work on your Revell Lancaster. My word, that's some exhaust staining you have there. Looks like she's been running a bit lean on all four !

Cheers,

John

Edited November 30, 2008 by John B (Sc)

[DHP]

It seems fairly clear. The main and outer wing sections were both set at 7 degrees wrt datum. I'd accept Francis Mason's reading of the specs rather than any number of pictures. Mr Mason was a senior designer for Hawker, so I reckon his figures can be taken as likely to be accurate! Yes, taken from one book, the aircraft rigging manual. As an engineer that is the only final authority I'd accept. The Lincoln is quoted as having the same settings.

Regardless of loadings, overloadings, ageing etc., any aircraft which when dimensionally checked was out of true tolerances would have been withdrawn for check, overhaul and repair as appropriate before flying again. I expect if we were to ask the BBMF ground crew, they will know in which attitude and configuration the dihedral requires checking. Generally this will require the unloaded aircraft to be trestled to a level fuselage datum position. The wings would also be trestled - stencils were applied for this purpose. As peebeep says, the dihedral measurement could tahen be assessed, while trestled.. And it is wrt datum, which will be shown on the aircraft rigging drawings, or defined precisely in the rigging manuals. So checking the apparent dihedral from photos of the BBMF machine on the ground, while fun, won't help at all. Angular assessment (from what reference?) is not possible at all and loading state etc. is not known.

Note that it would also have been necessary to specify where on the wing that value was taken – the wing tapers in frontal view and in plan. It also has washout built in. Aaargh - a complex 3D shape. A value may have been taken using the mainspar line along the undersurface of the eing, or a value taken to a specified point on a particular rib. It's not an easy exercise, requires some rigour and precision - which is why aircraft riggers & maintainers sometimes get tetchy.

I expect dihedral settings will be one of the items checked typically at each Cof A - every three years? Alternately it may only be a check done if there are any reported oddities in the handling. Also any significant change should be visible to the crew on general inspection.

That said, what miggers (Mark) says is entirely fair - the aircraft now at Hendon has been out of service for a long time. It will have been left loaded, and overloaded frequently, it presumably has also been dismantled and reassembled a number of times since it was last checked and approved for flight - I presume the outer panels can be removed ~readily? How much allowance for rigging adjustment is there? Its long ground period may well have resulted in further sagging of an aged and probably somewhat corroded structure.

In flight I'd expect the flexing to be several degrees normally and a darn sight more at max overload. Aircraft wings flex much more than people think - I recall watching a Boeing 707 as we went through a thunderstorm. Very impressive. A glance at any photos of max load tests will show astonishing flex before break. I believe the Boeing manual quoted a max tip upwards deflection of around ten feet from the unloaded ground 'datum' before failure. That was a long time ago and I don't have the manual to check. (As someone else said they had better flex. Rigid is not good.)

Of course if you want to see serious wing flexing in flight have a look at modern glassfibre or carbonfibre sparred sailplanes. Wow.

Mark - nice work on your Revell Lancaster. My word, that's some exhaust staining you have there. Looks like she's been running a bit lean on all four !

Cheers,

John

The exhaust staining is caused by the tetral ethyl lead put in the 100 octane fuel to prevent pre-detonation. Naturally, an engineer will lean out the engines to provide max endurance, but that should not cause excessive exhaust stains.. Most high time Lancs were well stained and weathered....those that lasted that long!

Derek

[DamienB]

I'd accept Francis Mason's reading of the specs rather than any number of pictures.

In flight I'd expect the flexing to be several degrees normally

Which is it then - a single book figure, or a range?

If you are comparing a model's appearance to the real thing then reference to a photograph of the real thing is entirely acceptable, and some ideal book figure is about as much use to you as the proverbial chocolate fireguard.

[Graham]

Here are a few more Lanc shots one from head on and one from behind while landing, and they show a dihedral that is bigger than the Revell kit. If I remember right the head on one was a flight prior to squadron delivery and the rear view was after a test flight so both Lancs would be quite light in weight. I posted the comparisons between the kits in an earlier thread and I still think the Airfix wing is the closest to the real thing.

Linky to Lanc pics

http://www.lancaster-archive.com/lanc_photos_flight.htm

Linky to thread with the kits

http://www.britmodeller.com/forums/index.p...mp;hl=lancaster

Graham.

[DHP]

Which is it then - a single book figure, or a range?

If you are comparing a model's appearance to the real thing then reference to a photograph of the real thing is entirely acceptable, and some ideal book figure is about as much use to you as the proverbial chocolate fireguard.

When built, the wing dihedral was set at 7 degrees. This is also the quoted figure in the Air Publication for the Mark 10 Lancaster. You can, of course, build your model any way you want, but the irrefutable fact is that the Revell kit is a bow-wow. And... I don't see how ever much loading will reduce the on-ground dihedral by four degrees...

So, let us agree to disagree.

Derek

[AnonymousA667]

the irrefutable fact is that the Revell kit is a bow-wow.

Somebody forgot to mention this fact to Mike Grant ():

Mike did an extensive build report in a recent issue of Model Aircraft Monthly.

peebeep

[AndyL]

Bit harsh saying the Revell offering is a bow-wow. I built one this year, and thoroughly enjoyed doing it. And that's what model making is all about IMHO.

[DHP]

Bit harsh saying the Revell offering is a bow-wow. I built one this year, and thoroughly enjoyed doing it. And that's what model making is all about IMHO.

Agreed, modelling is all about enjoyment. What did you do to the kit? Did you replace the wheels? Did you fix the dihedral? Is the mid-upper turret too high? Did you rescribe?

Cheers,

Derek

[DHP]

Somebody forgot to mention this fact to Mike Grant ():

Mike did an extensive build report in a recent issue of Model Aircraft Monthly.

peebeep

Nice work. Pity about the Matchbox trenches. No Lancaster I ever worked on had them, nor the one at the CWH. Did Mike replace the main and tail wheels? Or was this just a good build, out of the box?

Derek

[AndyL]

Agreed, modelling is all about enjoyment. What did you do to the kit? Did you replace the wheels? Did you fix the dihedral? Is the mid-upper turret too high? Did you rescribe?

Cheers,

Derek

Derek,

The answer is a no to all those bar the mid upper turret. There was a short shot on one half of the glazing, so Tim aka theplasticsurgeon donated a spare Airfix mid upper and I installed that. I was planning to use Quickboost .303 barrels on it, but Hannants were out of stock when I was there.

Cheers

Andy

[Miggers]

Thanks John.

After much studying of the Lancaster at War series and many other Lanc publications I have,I soon came to the conclusion that they gained their exhaust stains very very quickly.

A combination of 150 octane,high altitude and F/E's not wanting to run out of petrol so running 'em as lean as they dared soon saw to that.

Derek,I certainly,certainly do not think the Revell kit a bow-wow.It is the best at the moment that's available and certainly looks like a Lanc when built.

Yes the wheels are naff,the guns awful and the m/u turret sits a bit too high,but for the main two options in it,paddle or narrow prop blades,shrouded or unshrouded exhausts,for the price it's unbeatable at the moment..

The Airfix offering is,for general outline,still regarded to be the best,but needs far more work to bring it upto scratch.

The Hasegawa is very good but needs a lot of work/and or money(pe and resin) to get it there.

Mark

[keefr22]

Nice work. Pity about the Matchbox trenches. No Lancaster I ever worked on had them, nor the one at the CWH. Did Mike replace the main and tail wheels? Or was this just a good build, out of the box?

Derek

Well, not meaning to be confrontational, but if you can't tell from those lovely clear pics, doesn't it suggest that the said items in the kit aren't actually that bad......??

Keef

[AnonymousA667]

Did Mike replace the main and tail wheels? Or was this just a good build, out of the box?

I would suggest you either ask him yourself - he posts here as strangeways - or get hold of the article.

peebeep

[Heraldcoupe]

Well I won't argue that the kit has no issues, but a bow-wow it certainly isn't. The engineering is excellent, with all sub-assemblies going together nicely, and test-fit to each other very well indeed. I have some sink marks above the wheel well on the righthand wing, other than this I don't anticipate any need for filler.

I will alter the aileron hinge line on the top surface of the wing. Now I know it's wrong, it sticks out like a sore thumb. The dihedral may well be just as much of an issue, but it really doesn't jump out at me in the same way. I think this is down to the way the aircraft is photographed and observed on the ground, it seems almost impossible to judge the dihedral from any normal viewing angle with the the aircraft at rest.

The cockpit also bothers me, plenty of detail but lacking in absolute accuracy. I've replaced the pilot's floor and the navigator's table with plasticard, with plastic strip used to make ribbing in the areas covered by the oversized kit floor. All simple stuff which shouldn't really be necessary, but hardly taxing.

Having had the seed planted in my mind, I can see something amiss with the front turret, but I'll reserve judgement until I can test fit it in the assembled fuselage.

What bothers me most is the taper and washout at the wing tips. I didn't notice this until the wings were together, and Ambroid Pro-Weld does't come apart nicely! I may resort to running a razor saw between the two halves, which would allow me to insert a spacer to correct the profile. If I'd spotted it earlier I would consider adding a spar to spread the wing halves apart, just at the centres. I'd welcome any other opinions on this as no-one else seems to have mentioned this as a problem.

The mid-upper turret won't be an issue this time as my subject doesn't need it. There will be others, shouldn't be too difficult to drop it a bit when the time comes.

Problems aside, I am really enjoying this build. Having struggled with some real stinkers of late (still need to finish off my Italeri/MPM Wellington - now that is a bow-wow!), this reminds me that the hobby is supposed to be fun.

Cheers,

Bill.

Edited December 2, 2008 by Heraldcoupe

[jRatz]

A question -- I have seen the comment about round or oval slotted gun barrels & know QB has both available.

Other than the obvious round/oval difference, whats the difference ? How would I know which are correct for any given Lancaster other than by seeing a photo clearly enough ?

Thanks,

Edited December 2, 2008 by JohnRatzenberger