Mysterious tach markings

[VNugget]

I was looking at pictures of Russian acro types, and found this Su-31 cockpit on A.net. See those stick-on markings with the decreasing numbers on the tach? What in the hell are they? I've been racking my brain over it, and the best I could come up is that it's TBO... heheh. If you want more than 3 hours out of the engine, better pull it back a little. If you only run at idle, you can make it all the way to 9 hours, if you're lucky TrafficInSight suggested that it might be the maximum number of turns of a spin recovery before you gotta bail out... who knows

So... any ideas?

 

[ISaidRightTurns]

I would say quick reference to power settings for manuver entry. Loop, must be a 4. Inverted pass, must be 2......

 

[U-I pilot]

Looks like you got it.....if you look at the pattern it has those numbers on there for each maneuver.....
Pretty neat.

 

[FN FAL]

Looks like you got it.....if you look at the pattern it has those numbers on there for each maneuver.....
Pretty neat.

Yes...set max manifold pressure and then use the prop lever for power changes, that's what I would do.

 

[VNugget]

Nah, I don't think it's that. First of all, the numbers on the pattern card are just the sequential number for each maneuver. Second, why would one not just adjust power with the throttle, like the airplane was designed? Especially on a boosted engine. Also, I've never done hard acro (or any acro on a constant speed prop) but from what I've heard, they just leave the throttle wide open for most maneuvers. Third, even if they were power settings for different maneuvers, they wouldn't be sequential, and perfectly spaced out right down to idle RPM.

Gahh.... I wanna know, dammit!

 

[erj-145mech]

I think that thats the power setting for the given "G" loading, ie. lower setting for a higher G, to keep from over stressing the airframe.

 

[ISaidRightTurns]

I think that thats the power setting for the given "G" loading, ie. lower setting for a higher G, to keep from over stressing the airframe.

I would like to change my answer.

 

[A Squared]

I think that thats the power setting for the given "G" loading, ie. lower setting for a higher G, to keep from over stressing the airframe.

I don't think that's very likely. The Tach is graduated in percent of max RPM

100% would be 2950 (crank speed) so you're saying ath at 9g, you would have to have the engine turning at 737 RPM or less (the 9 is stuck at 25%) in order to keep from overstressing the airframe? If it was some sort of airframe limitation don't you think it would be printed permenantly *in* the tach instead of stuck outside with little stickers?

 

[sbav8r]

If it was a structural load limit, I would imagine that it would be a airspeed markings not tach.

 

[erj-145mech]

If you notice, all of the range markings are home made, and there are no slippage marks on the bezels.

If you were at 8 g's, where would you have the power set at?

I have expereince on French, English, Polish, Czech, Japanese and Russian foreign manufacturered aircraft that are experimental/exhibition category in this country, and this is typical of the markings. Instrument shops in this country can't remark the dials because they are marked with radium paint to facilitate viewing in dark conditions. The radium is now considered haz-mat, and most shops will refuse to open the cases on the instruments.