Performance Mods

[hydroguy2]

Getting ready to do some modifications to Aurora, but didn't have a good set of numbers to use as a basis. Today was one of those rare winter days along the Rocky front. Cool, but not too cool but mostly sunny and calm. Since it was Superbowl, I left work early for a little Pregame fun. The valley can get a little narrow to do a good 4way run, so for a base numbers and easy repeatability I will do a 2way. I went north to warm up the engine before turning south. Found smooth air at 7000'msl, 6650'DA. So WOT, 2600rpm 25"mp rewarded us with 173kts IAS 190kts TAS(but I have ~2kt error at this speed) so I'll call it 188ktas.

Return run was 188-189, but didn't seem as stable and was harder to hold consistent numbers. hard to snap a pic also when at race speed.

Now to start making mods and then more testing.

 

[Bob Axsom]

Can you do a three leg run in your valley?

The NTPS spreadsheet works very well but you have to do a three or four leg test to use it. It is good to pick a density altitude to make your runs at so the results of runs over time are directly comparable. You have a very fast airplane there in my opinion and I think you are right to get a really reliable base line for you development work. Paul Lipps always said the two way approach is good and even wrote a published article in support of it. I'm guessing your speed under these conditions is 188 kts which is about 4 kts faster than the best I have achieved so far (but I still working on it). I did do 197.031 kts in the competitive two way speed run at Courtland, Alabama in 2010 but they allowed you to roll into the pass from around 1400 ft AGL as long as you were at level 200 ft AGL 5 seconds before entering the trap. I was still burning kinetic energy half way through the pass. My official starting baseline before the first speed mod was added was 170.67 kts. Using the test method I have for my own tests I have never been able to break the 185 kt barrier - the best speed using my test method has been 184.4 kts

Good luck, it is a wonderful but often disappointing pursuit.

Bob Axsom

 

[hydroguy2]

I've tried to do the 3 or 4 way NTPS runs, but the valley gets narrow at race speed. It seemed like I always ended up getting smacked by wind coming over the various ridges. So I figured for a baseline a repeatable 2 way test would work.

I'll be cleaning up my upper intersection fairings and adding a tailwheel fairing for the next test. New wingtips are another test after they get built, but not sure if I'll see an big improvement at this altitude.

OF course, not sure if I'll see any improvements in any of this work as you have found out.