bongodriver

it's confusing for you? despite the fact CoG has a direct effect on aircraft stability? From the very document you linked: Stability and Balance Control Balance control refers to the location of the CG of an aircraft. This is of primary importance to aircraft stability, which determines safety in flight. The CG is the point at which the total weight of the aircraft is assumed to be concentrated, and the CG must be located within specific limits for safe flight. Both lateral and longitudinal balance are important, but the prime concern is longitudinal balance; that is, the location of the CG along the longitudinal or lengthwise axis. An airplane is designed to have stability that allows it to be trimmed so it will maintain straight and level flight with hands off the controls. Longitudinal stability is maintained by ensuring the CG is slightly ahead of the center of lift. This produces a fixed nose-down force independent of the airspeed. This is balanced by a variable nose-up force, which is produced by a downward aerodynamic force on the horizontal tail surfaces that varies directly with the airspeed. If a rising air current should cause the nose to pitch up, the airplane will slow down and the downward force on the tail will decrease. The weight concentrated at the CG will pull the nose back down. If the nose should drop in flight, the airspeed will increase and the increased downward tail load will bring the nose back up to level flight. As long as the CG is maintained within the allowable limits for its weight, the airplane will have adequate longitudinal stability and control. If the CG is too far aft, it will be too near the center of lift and the airplane will be unstable, and difficult to recover from a stall. [Figure 1-2] If the unstable airplane should ever enter a spin, the spin could become flat and recovery would be difficult or impossible. If the CG is too far forward, the downward tail load will have to be increased to maintain level flight. This increased tail load has the same effect as carrying additional weight; the aircraft will have to fly at a higher angle of attack, and drag will increase. A more serious problem caused by the CG being too far forward is the lack of sufficient elevator authority. At slow takeoff speeds, the elevator might not produce enough nose-up force to rotate and on landing there may not be enough elevator force to flare the airplane. [Figure 1-3] Both takeoff and landing runs will be lengthened if the CG is too far forward. Now we all know tail ballast is going to change the CoG and push it rearward, we also know that a forward CoG is beneficial to stability, so why add weight to shift a CoG rearward on an unstable aircraft?......unless of course the aircraft is not really unstable and has plenty of static margin in order to put ballast to correct a forward CoG from a heavier engine.

nobody has said that the ballast was for correcting stability, in fact pilums last posts make that very clear. in fact you have evaded entirely what his last posts really mean in quite a bizarre fashion.

I fly for Classic Wings, they operate 3 Tigers, G-ANZZ, G-APAO, G-ANRM

November....no it wasn't me then, almost certainly one of my colleagues finishing off the season.

I like the pop up label for the Tiger Moth, I am intrigued as to wether it might have been me flying the Tiger in the pic, what date was this taken?

But testing the effects of ordinance, retro fitted aft fuel tanks and high trans sonic speed regimes are not indications of any inherent stability issues, they do however indicate a diligence on the part of the British for testing stability and control.....it really doesn't reflect the theory you try to push about British stability and control standards and methodology. It is rather unsurprising that the British were less advanced in aerodynamic research than the Germans, the Germans had decided they wanted to murder large portions of the world population many years before and spared no expense in inventing ways to do it.

Se also clutching at straws.

on reading carefully it really makes no suggestion at all of a stability issue, failing to pull out of a vertical dive would really give some severe skin wrinkling though, I believe the 109 was adept at that demonstration :music_whistling:

Dramatically indeed.....considering there is no chart shown for the Mk IX but instead only the Mk V from your NACA Spitfire bible.

Well, Look in the airplane.... Next time I have a spare Mk IX laying around the house I will do that, though the last conversation I had with Sammy Sampson of the Battle of Britain memorial flight where he told me bob weights were fitted to MkV's only is sufficient for me. in the mean time I have been assuming you have all the evidence required? Actually it does not say 'as well' at all, it clearly states an aerodynamic solution was found period. Notice the problem 'disappeared' once the solutions were applied. Wild speculation as usual. again this is exactly what was intended, the stability of the spitfire was not an issue except for the MKV, it was the control sensitivity that was being addressed. You are the one providing all the ground to be covered.

The bob weight was a short term fix for issues suffered by the Mk V only. https://books.google.co.uk/books?num=19&id=2KdZBAAAQBAJ&q=59#v=snippet&q=59&f=false

I'm only saying they were only fitted to MkV's, I have seen no evidence of them fitted to any other mark.

I'm not confused

Dramatic is hardly the word, a noticeable difference perhaps.

Clearly nothing significant though.

Late elevators had an elongated horn. nobody is suggesting instability is due to the control surfaces or force per g gradient, but an aircraft suffering from weak longitudinal stability will suffer further from having light control forces, this really only manifested as a problem in the MkV hence the bob weight quick fix.

The bob weight was a short term fix for the MkV and it's CoG problems, only MkV's were fitted with bob weights, subsequent marks had a new elevator design bar some very early Mk IX's

Not really, the characteristics are famously benign, most pilots saying the handling was almost care free, Mark Hanna said one would have to be crass to ignore the ample warning from the aircraft but some people are trying too hard to promote this idea that if you even look at the elevators funny the Spitfire flips out of control.

There is nothing defined and quantifiable in speculation :lol:

Problem is Yo-Yo refers to a NACA test on a MkV which was the worst Mk for CoG. Anyway ED have more than enough real world Spitfire pilots (some of whom will have time on German counterparts) to validate the behaviours, most of them will find a Spitfire that is unpleasant to fly a bit odd.

Then you fly a different version to me, it is easy to stall/spin the Spitfire in Cliffs. Utter garbage embellished with your own speculation on how hard it is to aim through the gunsight.

:music_whistling: https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2004.pdf http://aviation.stackexchange.com/questions/2871/how-to-calculate-angular-velocity-and-radius-of-a-turn

it should make you think about any altitude other than sea level, at sea level the theory is that EAS=CAS=TAS as altitude increases these speeds diverge, in order for EAS to make sense an altitude must be given in order to determine the other speeds, TAS in particular being the one that is relevant to calculation of turn times and radius.

the use of rudder in this case is probably more a case of conditioned response, there certainly is no penalty for deflecting rudder even if it is ineffective during taxi. on the 109 there is no need to deflect rudder for braking as it has hydraulic toe brakes but it is kind of instinctive to use rudder during turns.