Merlin negative G cutout too quick?

[winny]

Originally Posted by Sternjaeger

..erm, you got me a bit confused mate, how can you exactly put a car into negative G load?

Crest of a hill...? Or, roll it.

Originally Posted by Moggy

Oh absolutely it does, but having documentational evidence puts the ball squarely into the other court and says "there you go fella, let's see what you can do with that."

I think the RAF\Supermarine ran negative G tests sometime pre-war at Martlesham Heath or Boscombe down. I truly believe the answers lay there in those records.

I still believe that better than papers and talk it's the real deal that solves any doubt. Even papers, made by men, could have been "retouched" in favour of this or that person/situation etc.. (think of aerial victories reports..),whilst first hand experience does hardly lie at all..

Having said this, it'd be interesting to read these records.

[klem]

Oh Gawd,

this is getting more surreal by the minute.

Common sense guys, do you really believe the MoD/RAF would have put it's most cutting edge fighter into service with an engine that persistently misfires in level flight with its normal turbulence and undulations.

Push-overs, yes, that's well reported on by the people that flew them but problems in normal flight? None that I have ever read and lets be honest no-one here has ever pushed one of those Merlins into negative G, you all only have your various written references to go by and so far I don't think anyone has found a report of the time or operation of those engines that says normal flight is a problem. Lets stay away from conjecture, guesswork and revisionism.

So, feet back on the ground (no pun), the model is too sensitive in normal flight, I leave it to the devs to determine where negative G effects should have an effect but atm its just plain daft.

[klem]

Originally Posted by Viper2000

.............. But if the people designing the aeroplanes have never flown them then it's unrealistic to expect them to imaginatively embellish the specifications given to them by the man from the Ministry, especially since they probably wouldn't be thanked for it anyway.

Bear in mind that Hawker and Supermarine were ahead of the MoD on aircraft development, both producing what they thought was best and better than the basic MoD specs of the time. Imaginative embellishment is precisely what they did to the gratitude of the MoD. Hawkers had all their experience of the Hart/Fury line from which the Hurricane directly descended (some of those had Merlin engines, do you think they never hit negative G in their life or development?) and Mitchell had all the Se5/Se6 development behind his work on the Spitfire.

Added to that, these aircraft had to be passed fit for purpose by the appropriate authorities, from normal flight to combat.

[II/JG54_Emil]

Originally Posted by klem

Common sense guys, do you really believe the MoD/RAF would have put it's most cutting edge fighter into service with an engine that persistently misfires in level flight with its normal turbulence and undulations.

Is the issue about believe or about knowledge?

[klem]

Originally Posted by II/JG54_Emil

Is the issue about believe or about knowledge?

Its about an absence of knowledge and the application of common sense.

[II/JG54_Emil]

I hope this is not going to be a sim of common sense.
Common sense is very often far off reality or truth.

Anyhow we have people like Sternjaeger and basically it should not be too hard for the developer to pick up the phone and call Tangmere and ask questions.

[IvanK]

I have just been talking to a friend who is current on Spitfire MKVIII,XVI,P40E,P40F and P51D and the Harvard/T6, Wirraway and Hudson. His day job
is an airline pilot, his Warbird flying is with the Australian Temora collection and also flies for a number of Warbird owners. Below is a summary of the conversation.

The discussion was to determine -Ve G effects and cut outs and RPM fluctuations and how they compare to what we have in COD.

COD RPM FLUCTUATIONS
On RPM Fluctions he was quite adamant that in the Spitfires which are running Hydraulic Constant Speed units the RPM is "Rock Steady" throughout a display. Now the MKI,MKII and Hurricane both have Hydraulic CSU's that are pretty much the same as those fitted to the MKVIII and XVI. The bottom line is we shouldn't be seeing ANY of the fluctuations we see at present.

Interestingly he made the comment that the Merlin powered P40F (currently the only one flying in the world) that has an Electric CSU is not so stable. In a typical display with fixed prop lever position he says the electric CSU is slow and this results in RPM fluctuations of around +-150RPM over 2-3second period. The Allison P40E he flies has an Hydraulic CSU and like the Spits is also rock steady.


COD -Ve G CUT OUT
Now obviously the Spit VIII and XVI don't have an issue with -Ve G but the Harvard he flies does. It suffers similar issues that the early Merlins do. I asked him at what G value does the engine start to cough ? The answer was 0G. As long as the G is positive he said there were no issues. Normal flying is unaffected by the cutout phenomena. This is the best level of information we have at present. This is also backed by a separate reference from a UK Harvard pilot spoken to by sternjaeger and referenced in an earlier post. It bolsters the position that what we now experience is too sensitive.

I post this here for info.

[klem]

Originally Posted by II/JG54_Emil

I hope this is not going to be a sim of common sense.
Common sense is very often far off reality or truth.

Anyhow we have people like Sternjaeger and basically it should not be too hard for the developer to pick up the phone and call Tangmere and ask questions.

I work at Tangmere as a volunteer, I'll go through our library again. I'll also ask around and talk to a friend there that maintained the Grace Spitfire (not a MkI/II) but I think IvanK has already covered the 'AFAIK' aspect. What I really need is a Hurricane MkI veteran to walk through the door

Originally Posted by klem

I work at Tangmere as a volunteer, I'll go through our library again. I'll also ask around and talk to a friend there that maintained the Grace Spitfire (not a MkI/II) but I think IvanK has already covered the 'AFAIK' aspect. What I really need is a Hurricane MkI veteran to walk through the door

Klem that would be great! And yes, meeting a BoB veteran would be great, but be prepared for some disappointment: after many years memories are not that sharp anymore I met a WW2 luftwaffe pilot who had confused memories and apologised saying "people expect me to talk about those days like it happened yesterday, but it was just 5 years over 75 of my life, SO many other things happened!"