Sender: <marv@lancaironline.net> (Marvin Kaye)
To: lml
Date: Mon, 30 Dec 2002 19:41:28 -0500
Message-ID: <redirect-1942026@logan.com>
From: AVIDWIZ@aol.com
Subject: Scimitar Prop
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Gentlemen:

Although I hesitated to provide any preliminary details at all, I thought you might be interested.  I should remind you that in my initial posting I stated that these were very preliminary numbers.   So a few updates:

1) The model of the Scimitar is the one Heidi at Lancair currently sells and was profiled in FLYING 2 months ago.   The old prop was the one Lancair sold in 1997.

2) The climb performance numbers are derived from looking at the VSI and I will admit that the OAT from the old sample days varied.  HOWEVER bottom line is there was  a distinct improvement.  My aircraft has NEVER before been able to sustain a 2000 FPM climb and stay in temp limits ... now it can.

3) As for TAS I have not posted the numbers because I do not trust the Sierra readout.   The OAT is not correct and the AHRS is the old Watson model and has not yet been replaced with the crossbow model though I am told that SFS will be getting one for me soon.  As such quoting TAS from the old samples would be meaningless.   However, using the computer model on the National Test Pilot School web site at www.ntps.com.  We flew 3 legs at the same power settings, prop settings, and altitude.  Then plug the GPS ground speeds into the formula and VIOLA, the TAS appears.  The last figures we have using this showed the following:

11,500 MSL 31mp 2450 RPM 25 GPH 201 to 205 KIAS and 237.5 KTAS

The reason I did not post these previously is that the sample we did with the old prop did not have this method used so are not as accutate.

CONCLUSION:
I think that while I agree with everything mentioned as to the potential flaws in our testing methods, the bottom line is that this prop climbs better and sustains 6-12 knots more airspeed then the old one. I am confident of this because indicated airspeed has never exceeded 200 Kts in this plane and now it does.  Using indicated airspeed is the only reliable method we have to compare because of the limitations cited above.  If anyone would like to take the time to make more in depth comparisons, I still have the old prop and would be happy to loan it to you for testing.

So, does this Scimitar prop out perform all others?   Who knows.  If someone had the time they could do a prop shoot out with all the contenders but in absence of that I am happy with what I have.   My plane still has speed issues which are being addressed and I will let you know the results.

Regards,


Dave Riggs