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  #361  
Old 06-06-2012, 12:01 AM
Bob Axsom Bob Axsom is offline
 
Join Date: Mar 2005
Posts: 5,685
Default 6-5-12 Test Without Cover

I removed the cover and reran the test twice with the new bump which is a continuation of the baffle between the engine and the bottom of the firewall.



The speeds of the two tests were 181.8 and 181.7 kts respectively and both are faster than the two tests of the same bump with a cover with large exhaust cutouts.

All tests in the order conducted:


All tests sorted by speed and ranked fastest to slowest:


Bob Axsom

Last edited by Bob Axsom : 06-06-2012 at 05:44 AM.
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  #362  
Old 06-06-2012, 10:56 AM
johnny stick johnny stick is offline
 
Join Date: Dec 2008
Location: Los Angeles, CA
Posts: 301
Default You got it

Bob,
It looks like you have acheived success. Good job and great perserverance. A few more tweaks and you could be well over the 185 mark.
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  #363  
Old 06-06-2012, 12:07 PM
Bob Axsom Bob Axsom is offline
 
Join Date: Mar 2005
Posts: 5,685
Default I have a good feeling about it as well

When I flew the test yesterday three normal race prep items were not done so the results could have been a fraction of a knot higher. The other parameters I noted: RPM 2720, CHT 1=362, 2=373, 3=366, 4=inop, EGT 4=1299.



At least superficially it appears that the new bump is the best so far and that covers are worse than no covers. The flow fence info is not as clear. The best speeds so far are the thick flow fences with the vertically tapered aft end with all the cover mount hardware attached.

Bob Axsom
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  #364  
Old 06-06-2012, 09:21 PM
Bob Axsom Bob Axsom is offline
 
Join Date: Mar 2005
Posts: 5,685
Default 6-6-12 Switch fences

This has got to be better:



Hope to test it tomorrow.

Bob Axsom
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  #365  
Old 06-07-2012, 10:27 PM
Bob Axsom Bob Axsom is offline
 
Join Date: Mar 2005
Posts: 5,685
Default Bad Luck Day

Pulling the plane out for the test flight I heard a strange noise from the Right MLG. Looking closely the inboard side of the rear half of the subfairing was rubbing the tire and a large chunk was missing.



I removed the subfairings from both main landing gear and flew the test but even though I previously stated I couldn't measure any benefit from them, it is not a directly comparable test. The speeds were slower at 180.8 and 179.9 respectively. I am going to have to go back to the modeling clay stage to get this rebuilt for the race in Washington on the 16th. I'm going to have to go without them in Carbondale, IL this Saturday (6-9-12). It will be a while before this test is ready to repeat.
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  #366  
Old 06-11-2012, 02:15 AM
Bob Axsom Bob Axsom is offline
 
Join Date: Mar 2005
Posts: 5,685
Default 6-10-12 status

The speed was good in the Big Muddy Air Race at Carbondale on 6-9-12 at just under 211 mph without the subfairings on the MLG, not tape, tiedown rings left in by oversight and not quite perfect flying so I think this outlet configuration is going to be a winner. I just got back from the hangar where I applied the first layer of fiberglass on the fairing, clay and tire. I use 24 hour cure EZ Poxy resin so this will take three or four days to complete through paint. and I have to fly to Ephrata, Washington for the Great Northwest Air Race III on Saturday so there is a good chance the test will be after I get home - we will see.







Round mold tire in route from Aircraft Spruce.

Bob Axsom
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  #367  
Old 06-21-2012, 10:53 AM
Bob Axsom Bob Axsom is offline
 
Join Date: Mar 2005
Posts: 5,685
Default 6-21-12 Status

The new mod has still not been tested. I flew from northwest Arkansas to Ephrata, Washington, then flew in the Great Northwest Air Race III and returned home. It needs the oil changed and a modification to the panel on the left side. The race speed at Ephrata was 216+ mph which is my best so far this year but that is with my best effort to work the wind and doesn't necessarily mean anything with respect to the top speed of the airplane.

Texoma 208.14
Taylor 208.84
Hill Country 212.86
BCAF 212.18
Terrell 206.28
Big Muddy 210.98
GNAR III 216.05

Yesterday the oil and filter arrived from Aircraft Spruce and I removed the cowl to start the oil change and mod examination. The left panel made of 0.016" 2024-T3 has been cut by the trailing edge of the exhaust pipe. The possibility of failure of the panel at this point was not unexpected because of the closeness of the exhaust pipe and the thinness of the aluminum panel. The cut is a very straight line conforming to the edge of the exhaust pipe approximately 3/4" long and 1/32" wide. The operating time was a little over 20 hours. Closer examination revealed cracks in the panel starting at the cut and progressing forward toward the front of the plane in an irregular pattern. The nature of the cracks appears to me to be exactly the same as the failed panels observed after the completion of the Hill Country race but they are isolated to the area directly aligned with the side of the exhaust pipe. No cracks extend from the rear of the cut in the panel. I may replace the panel with one made of stainless steel or I may put in a bump strip of stainless steel or I may re-rig the exhaust pipe suspension (not an easy job with all the baffling I have in the lower cowl).

Bob Axsom

Last edited by Bob Axsom : 06-21-2012 at 11:50 AM. Reason: typo
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  #368  
Old 06-23-2012, 02:26 PM
Bob Axsom Bob Axsom is offline
 
Join Date: Mar 2005
Posts: 5,685
Default Damaged panel removed and cleaned up



There are cracks on on both sides of the exhaust pipe cut. I plan to replace the easily replaceable panel with one made of 0.016 stainless steel and currently I'm thinking an extension link in the exhaust suspension.

Interesting critter on my rear window (it is about 6" long):



Bob Axsom

Last edited by Bob Axsom : 06-24-2012 at 01:48 AM.
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  #369  
Old 06-23-2012, 08:28 PM
whiskeypapa whiskeypapa is offline
 
Join Date: Jul 2006
Posts: 60
Default

That's a Walking Stick. One of my favorite insects!
__________________
Billy Prouty
RV-4 Prebuilt
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  #370  
Old 06-26-2012, 12:04 PM
Bob Axsom Bob Axsom is offline
 
Join Date: Mar 2005
Posts: 5,685
Default Little interuption in the experiment work

Observed a crack in the FAB mounting plate when I removed the cowl for the oil change.

When I took that off I noticed a cracked rivet head by one of the platenut installations on the FAB mounting flange. When I tried to drill the rivet the whole installation fell off in my hand.



As I worked that salvage with a ring doubler I noticed a tiny crack about 1/4" long at each end of the FAB metal top at each end of the slight bend about 4" back from the front.

My fix for all of this was to drill out all of the rivets holding the fiberglass bowl to the top plate install a ring doubler on the inside with a spacer plate where the piece had broken out. Stop drill the cracks, debur the holes and add doublers across the end of the bend area.



I also have to replace a vacuum hose (ordered Saturday) so the long awaited test of the new "bump" with the triangular fins probably will not happen before Thursday

Bob Axsom

Last edited by Bob Axsom : 06-26-2012 at 12:07 PM.
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