Yak 1 restoration

Can’t wait to see that lovely aircraft !! i hope they will come to france and honor our heroes from Normandie Niemen, because until now none of them saw again the Yak1 they used during 1943

…Ergo, in this manner is it possible that the flying weight of such examples rather sneaks upwards with the inclusion of various modern items, repairs, new structure and so forth?

I would be very surprised by any examples of that. In the UK at least, a newly restored machine is weighed. Why, eh? To see it’s within the weight and ballance requirements I understand.

I can’t think of any ‘modern’ equipment that would weigh as much as that removed – as I listed before, guns, ammunition, associated equipment, W.W.II batteries (very heavy) and instrumentation, oxygen and turbocharger systems, armour of course. Many have fewer fuel tanks or fly with reduced fuel loads.

If ‘repairs and new structure’ add any significant weight you really don’t want to shop there again.

Regards,

Sorry I had to correct my weight figures. I read the wrong line on the weight report.
No armour plate or guns in the airplane.

Cheers, Bluecorsair. This example works out to 4290 kg, which is essentially the same as a wartime service aircraft. Fascinating. Is the P-51 you mention here fitted with various items such as guns and armour, I wonder?

If it is not, does this suggest that perhaps many Warbirds are really not flying at significantly reduced weight by way of ‘demilitarisation’? I can understand surely that a modern Warbird would never need to be the subject of such drastic, shall we say, “weight discipline” as with a combat machine. Ergo, in this manner is it possible that the flying weight of such examples rather sneaks upwards with the inclusion of various modern items, repairs, new structure and so forth?

I hope we see some more examples of Warbird take-off weight. This subject is becoming more interesting by the post!

Is anyone aware of some examples of actual take-off weight for various Warbirds? I would be curious to compare some of these weight values with those from wartime aircraft. Just what does a “typical” (I realise the term is fully stretched here) P-51 Warbird weigh at take-off at an air show? I’ve no idea….[/QUOTE]

P-51

empty weight 6,900 LBS
fuel/oil 1,000 LBS
pilot/parachute 225 LBS

8,125 lbs at take off

Have I missed your point? Was it not that most Warbirds are operated in what one might call a ‘demilitarised’ condition? That is, with the various combat related bits (armour, guns, ammunition, etc) either removed or replaced by lightweight replica parts, no? I apologise in the case that this is not what you intended.

Err. Confused?

That’s correct, so most warbirds are operating at lighter weights than they did in service. They are arguably better maintained, too. Balanced against that is they are flown a lot less aggressively and engines are neither pushed nor thrashed or over-boosted as they often were in the war.

However, I think the observation for adding weight works equally well in the other direction, i.e. by removing it. An I-16 with a proper structural weight and demilitarised in this way would benefit more in terms of flight behaviour than a P-51 similarly demilitarised.

My point was if a warbird was ‘structurally overweight’, the lack of that armament weight would bring it back to its wartime weight or below. (Some guns and armour are required for weight and balance, the DH Vampire being a good example.) So yes, as you say, but…

As above power is usually more carefully managed; and truck engines are probably more significant performance detraction than a (small) percentage overweight. Larger overweights would be significant of course; 25% is poor engineering, and you are heading into structural failure risk due to mass and acceleration issues. Aircraft are a ‘best compromise’ – changing elements of an established design has nasty knock ons, which is one reason why the CAA are very reserved about near authentic replicas like Flug Werke FW190s.

Basic flight theory says the four factors are lift, thrust, weight & drag. As we’ve seen weight is non original in almost all cases (always lower); thrust is rarely even near maximum; lift and drag should be about the same, excepting minor items such as bomb-racks. But again, the g loading sustained, and thus the rest of combat performance will bear no real relation to wartime ‘there’s another one when I get back’ lifesaving wringing it out.

Be that as it may, this rather begs a fascinating question. Is anyone aware of some examples of actual take-off weight for various Warbirds? I would be curious to compare some of these weight values with those from wartime aircraft. Just what does a “typical” (I realise the term is fully stretched here) P-51 Warbird weigh at take-off at an air show? I’ve no idea….

I treasure my ignorance. Pointless to look for a typical one, better to ask for specific weight/performance data with the configuration data for a selection of several.

A new restoration, Happy Jack’s Go Buggy is fitted with the rear fuselage tank and drop tanks. I understand it’s been flown with the rear tank full (IIRC?) and as this as a news item for the Stangheads, it’s not common. (My guesswork.) The Mustang questions a natural for Mark V. Where are you?

Certainly until recently very few were flown at max combat or overload weights, nor combat manoeuvres, heights or speeds.

Given that most of us staring at the aircraft whizzing by couldn’t quantify the speed to the nearest 30mph and the turn radius to the nearest 25 metres, and show and private warbird flying is not combat flying, it’s all pretty academic performance differences. It’s pretty, it’s fun, sounds and looks nice (and historical) but it doesn’t teach us a lot about how they really performed.

Regards,

Have I missed your point? Was it not that most Warbirds are operated in what one might call a ‘demilitarised’ condition? That is, with the various combat related bits (armour, guns, ammunition, etc) either removed or replaced by lightweight replica parts, no? I apologise in the case that this is not what you intended.

However, I think the observation for adding weight works equally well in the other direction, i.e. by removing it. An I-16 with a proper structural weight and demilitarised in this way would benefit more in terms of flight behaviour than a P-51 similarly demilitarised.

Be that as it may, this rather begs a fascinating question. Is anyone aware of some examples of actual take-off weight for various Warbirds? I would be curious to compare some of these weight values with those from wartime aircraft. Just what does a “typical” (I realise the term is fully stretched here) P-51 Warbird weigh at take-off at an air show? I’ve no idea….

You’ve missed my point. Assuming the Yak 1 comes out structurally overweight (which is an assumption I’ve no evidence we need to make to that aircraft – the re-construction abilities of the organisations involved will be more appropriately skilled than those which built the I-16) then you could return to the book ‘laden’ and ‘unlaiden’ weights simply by adjusting the weight of other items, not vital to flight, such as the armament and ammunition. Simple, and given, as I said, most warbirds are operated without all combat equipment, almost inevitable.

Now you need to decide if lighter equipped Spitfires and Mustangs may embarrass a more accurately weighted Yak 1. 😉

Obsession about weight for such an aircraft assume other usually changed weights, particularly armament, ammunition, radio, wartime battery and armour (where fitted) stay the same. The majority of warbird fighters flying are operated at significantly lower weights, sometimes with neat tricks as aluminium guns, and armour, but generally just ‘without’. Obviously the I-16 was an earlier generation, and Russian aircraft often had less ironmongery to tote around than their western equivalents – but the still had guns and shells.

Your point is well taken. But, in my view, with VVS designs I think the weight matter may be a bit more significant, really. It is something of a matter of proportion– the lighter the design’s target weight, the more perilous an increase in actual weight would tend to be.

For example, a machine like the I-16 would have a take-off weight around 1900 kg (depending upon the version, outfit, etc) and about 1000 hp available. Adding an additional 400 kg to this total (e.g. vis a vis an over-weight structure) would reduce the machine’s performance significantly.

For a P-51, the historical take-off weight was about 4300 kg with something like 1700 hp. Would adding an extra 400 kg (vis the same structural condition) even register on performance? Perhaps, but not by much.

Since Western designs tended to be bigger, heavier and more powerful, the effects of, say, such an increase in weight would not generally be as deleterious to behaviour and performance as with their lighter counterparts. Well, at least broadly speaking, in any case.

With respect on the Yak-1, specifically, I think it will be quite important to get this right. I am sure you will agree.

Sadly, the very advanced and clever wood-laminate techniques employed in Soviet aviation at that time are lost to us. Aircraft such as the I-16s (re-)built in Novosibirsk are a great example of this lost technology, as no one was found who recalled how to replicate the exact fuselage structure technique, nor what was the formula of the resin used in this construction (and so forth). The team, no matter how skilled (and they are), simply could not achieve the correct (and historical) strength values at the the historical weight.

Interesting. I’ve seen the restored wing at AJD, a few years ago now. IF I recall correctly, Tony Ditheridge said that the wing of this aircraft was the later version, made from short laminates, rather than the early one with longer pieces – a change required due to the lack of good enough long pieces of wood – that, however is going on a very rusty memory and shouldn’t be assumed correct.

However if I was to develop a high performance wooden machine, I’d do it in the UK; even replicating ‘lost’ foreighn high-technology. I’ll be surprised if the relatively solid wing of this aircraft were to be as crudely overweight as 25%!

Ergo, the fuselage structure is about 25% over-weight, seriously affecting the aircraft’s behaviour; indeed, more so by far than operating with a Western motor, propeller, and such like.

I understood the very non-prototypical prop boss on the I-16 was to cover the (adopted) four blade hub for two-blades – and the engine and four-blade prop combination were from the An-2. A transport engine compromise, not a western one.

Obsession about weight for such an aircraft assume other usually changed weights, particularly armament, ammunition, radio, wartime battery and armour (where fitted) stay the same. The majority of warbird fighters flying are operated at significantly lower weights, sometimes with neat tricks as aluminium guns, and armour, but generally just ‘without’. Obviously the I-16 was an earlier generation, and Russian aircraft often had less ironmongery to tote around than their western equivalents – but the still had guns and shells.

If the team manage to keep the Yak-1s weight to historical proportions, the result will be a correctly performing Yak-1 complete with its historically superb handling. Such an aircraft will cause many a Western jaw to fall precipitously in astonishment, and draw attention correctly to the outstanding capabilities Yakovlev’s fighters.

That would be nice. However there are none so blind as those who will not see. Russian fighter efficacy is very evident to those who care to research it, like yourself – however it won’t be ‘as good as a (yet another) Spitfire/Mustang’ for many enthusiasts. :rolleyes: A rare type like this is, I think, very exciting.

Regards,

The wing has already been rebuilt by AJD Engineering in the UK.

Having a running Klimov will, of course, be very important to the behaviour of this restored Yak. However, this is example is important not for the engine, but for the fact that it will be the only flying Yak with a proper structure. Or, at least we hope!

Sadly, the very advanced and clever wood-laminate techniques employed in Soviet aviation at that time are lost to us. Aircraft such as the I-16s (re-)built in Novosibirsk are a great example of this lost technology, as no one was found who recalled how to replicate the exact fuselage structure technique, nor what was the formula of the resin used in this construction (and so forth). The team, no matter how skilled (and they are), simply could not achieve the correct (and historical) strength values at the the historical weight. Ergo, the fuselage structure is about 25% over-weight, seriously affecting the aircraft’s behaviour; indeed, more so by far than operating with a Western motor, propeller, and such like.

HAC are of course hugely experienced with wooden structures. But, how will they recreate the original birch-bakelite laminate wing skinning material (called shpon), one wonders? Will the resulting wing be over-weight, as well, or will another suitably light substitute be found? The answers to these questions will be revealed in time.

Such structural matters are paramount. If the team manage to keep the Yak-1s weight to historical proportions, the result will be a correctly performing Yak-1 complete with its historically superb handling. Such an aircraft will cause many a Western jaw to fall precipitously in astonishment, and draw attention correctly to the outstanding capabilities Yakovlev’s fighters.

I had forgot to mention there was a article in the JULY 2008 about the YAK-1. It had a brief history of the airplanes operational history. Also mentioning the engine rebuild progress. I was surprised to see the con-rod setup. The MERLIN and ALLISON use the fork and blade style. The RUSSIAN is more a master and articulating setup.

I haven’t seen it for a year or so but worth reminding how it was when recovered in 1990.

Mark

I saw the fuselage back in December and it’s far from leaping into the luft……. maybe another 2 yrs at least

Any pics?

Cheers,
C6

The YAK-1 restoration has fascinated me since it first began so long ago. The first I recall of it was a blurb in WARBIRDS WORLDWIDE in 1991. Seeing the photos of the rebuild helps a person understand the time and effort put into these restorations. Airplanes on the flightline and beautiful. But the paint,fabric,or aluminum skin cover all the restorers efforts. And bravo to HAC for the effort and dedication to rebuild a KLIMOV. This will make the airplane that much more special.

Is this the same a/c that was at Audley End in the 90’s?

Herman

I saw it yesterday and its looking good!

The fuselage was being built a Little Gransden circa 1992-93 so I would allow for a little longer on the project.