Ash 82 FNV MP ranges

[Tilt]

Firstly thanks for all the Lavochkin stuff (slats/glass/ etc).... I like the torque and the snatchiness of handling.....wing art work has been tidied up too it aligns on both sides now.


I think the manifold pressure still need s some modification re the indicated figures........... I can't tell if these are actually changing the power available.

eg the La7 seems to have WEP available at certain speed when travelling at 17 to 19 K  whilst at lower speeds and alts it drops of considerably (imo more than it should) before the 2nd speed of super charge is engaged.

Also the MP seems to creep up when this is engaged rather than step  up as I would expect. Except you can make the MP guage "blip" at just under 15K.

I have two sets of figures for La7 manifold pressures one in climb (not showing the effect of WEP)and one set a top speeds at some altitude increments.

The climb is off an early model La7 that had a slat and governer fault but should give some indication that MP did not drop as low as presently modelled in AH2.

The scanned gifs are very poor quality.............

Then there are later tests nicely typed that whilst  showing the actual MP's do not show the critical altitudes highlighted.

[Tilt]

http://www.tilt.clara.net/data/011.GIF

here you see that wep less critical altitudes are at 2000 and  5350m at the best climb speeds given.

You can also see that the 2nd speed of boost was applied at 4000m (two MP's given) some what lower altitude than used for higher speed level flight.

Further the MP never drops below 825 Millibars untill beyond the critical alt of the 2nd stage of boost.

[Tilt]

http://www.tilt.clara.net/data/009.GIF

Here we see the same ac in level flight trials.......again rem its got some faults on it.

now you can see thet the WEP is shown and that full MP is maintained except for a  period between 3300m and some where before 5000 m (usually the 2nd speed of boost is applied circa 4650m) so again it would not drop below circa 825 and indeed we see that the 2nd speed can be engaged at will by the pilot.

It has been engaged at diferent alts in these two trials

[Tilt]

http://www.tilt.clara.net/data/02.GIF

This data for a later ac in early 45 wraps up various  data on rpm,speed MP and altitude with endurance distances and times.

You may like to check it against your own.....

I would comment that AH2 is such a major step forward in this respect that I consider suggesting closer adherance to these recorded figures some what fussy in the light of progress todate.

Interesting to note that endurance is better at the lower alts that the La7 would operate in (until its done at 7000m where few La7's ever ventured)

[Tilt]

In conclusion the

I cannot see any fault  re variation of MP with speed and alt with WEP engaged. That AH2 has now.

In slow speed optimum climb you can engage 2nd speed at 4000m (13,000ft)

Yet at high speeds you would delay engaging 2nd speed until 4650 m (15,300 ft)

It seems therefore that the switching point is not alt related but MP related and that that MP is at 825 millibars (at max throttle/rpm).

Also once past the final critical altitude there is no futher increase in MP available from the engine system.

That WEP less critical altiude varies from 2000 m (6500 ft) in climb to  3300 m (10800 ft)  in fastest horizontal speed.