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  #351  
Old 05-22-2012, 08:47 PM
Bob Axsom Bob Axsom is offline
 
Join Date: Mar 2005
Posts: 5,685
Default Getting better focused

Today went well. The hardest part of some of these mods is the implementation details while preserving the quality of the airplane. It is so frustrating to do rough work to test a concept with things that are crude and it is a double edged sword ... Ah well. I've been fighting some infection with 300 Mg Clindamycin for the last week and today is the first one that I feel like I am good. Consequently I am better organized and patient with this one and it is going to look good and be a good installation even if it doesn't work and that makes me feel good.




Bob Axsom
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  #352  
Old 05-24-2012, 12:53 AM
Bob Axsom Bob Axsom is offline
 
Join Date: Mar 2005
Posts: 5,685
Default Just got home from the airport - good 12 hr day

It is amazing how little I got done but I'm using platenuts and screws To put this version together. I only had 8 single ear platenuts in my stash so ordered the total requirement (12) in regular, miniature and floating for 36 to cover any complications with next day air delivery. The next race is Saturday and this is Wednesday (well technically it's Thursday). Parts $24 shipping $35 There is no way everything is going to come together before the race. I'm still carrying the bug gut load from Texoma but washing is going to have to wait again. What I have together so far looks great.

Bob Axsom
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  #353  
Old 05-25-2012, 11:55 AM
Bob Axsom Bob Axsom is offline
 
Join Date: Mar 2005
Posts: 5,685
Default It will not be on the plane at Terrell, TX tomorrow

The support structure is done to a first cut stage but it needs more time to finish than I have before the race in Terrell, TX tomorrow. Going to have to put the plane back together, fly there, run the race to stay in the point hunt and come home to finish it before the race at Carbondale on 6-9-12.



Bob Axsom
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  #354  
Old 05-29-2012, 01:34 AM
Bob Axsom Bob Axsom is offline
 
Join Date: Mar 2005
Posts: 5,685
Default Spent 5 hours on it today 5-28-12

The right panel (bump?) skin is fitted and trial installed except for the trailing edge. I should work that out tomorrow.

Bob Axsom
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  #355  
Old 05-30-2012, 11:53 PM
Bob Axsom Bob Axsom is offline
 
Join Date: Mar 2005
Posts: 5,685
Default 5-30-12 The Big Muddy is only 10 days from now!

Obviously I did the right thing not trying to cram this in before the race at Terrell, TX last Saturday. I will have it done before the Big Muddy race at Carbondale, Illinois a week from Saturday. As far as the bumps are concerned they are essentially done except for securing the tail end. I will have to use some RTV which I did not want to do but I have some side gaps so I got to plug'm. I was successful in making the panels and support beams removable with a screw driver - it's more experimenter friendly that way - and no additional holes were added to the airframe.




The little stainless steel part is one of two that I will finish tomorrow to secure the trailing edge of the panels.



They are unique for each panel to match the interface. The relief cutout in the trailing edges provides a path for the outlet air from cowl zone 3 - oil cooler, blast tubes (when not blocked for racing), etc.

I plan to fly the first test using the cover with the exhaust cutouts. I haven't decided yet but I am thinking of enlarging the cutouts to match the exhaust pattern deposited on the inside during previous tests.

I hope for a knot out of this but expect nothing.

Bob Axsom
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  #356  
Old 05-31-2012, 07:52 PM
Bob Axsom Bob Axsom is offline
 
Join Date: Mar 2005
Posts: 5,685
Default Ready to integrate and test



The mod development work is done. Should be able to test tomorrow.

Bob Axsom
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  #357  
Old 06-02-2012, 12:06 AM
Bob Axsom Bob Axsom is offline
 
Join Date: Mar 2005
Posts: 5,685
Default 6-1-12 ready to fly but ceiling limited

When I used to drive up the 405 to LAX this was a common visual treat:



So why on this day was it in Fayetteville, Arkansas? Walmart shareholder's meeting perhaps ...

Anyway, as you can see 6,000 ft density altitude VFR for speed testing wasn't possible. Maybe tomorrow. I did enlarge the cutouts in the cover.




Bob Axsom
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  #358  
Old 06-02-2012, 04:37 PM
Bob Axsom Bob Axsom is offline
 
Join Date: Mar 2005
Posts: 5,685
Default 6-2-12 Flew two speed test same configuration

After flight photo (no shattered panels)



Results in test order:



Sorted by speed and ranked:



These are encouraging. I will probably fly this configuration at Carbondale, IL in the Big Muddy Air Race since it is fairly fast and I have so much cleanup to do to get ready. But all the fence and cover configurations need to be tested with these bumps. The two test results were only 0.6 kts apart even though it was bumpy and I could not meet the USAR Handicap procedure requirement of no deviation of more than 1 kt in a series of five samples 20 seconds apart. At 180.6 and 180.0 kts They rank 6th and 9th in the series of 23 tests. My gut feel is this configuration of bump is worth more study.

Bob Axsom

P.S. The Goodyear blimp is still at Drake Field - they must be giving VIP Walmart shareholders rides. I asked if the Goodyear blimp is the one I used to drive by on the 405 on my way to LAX and the pilot responded "No that one is still there, this one is based at Akron, Ohio."



BA

Last edited by Bob Axsom : 06-02-2012 at 04:44 PM.
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  #359  
Old 06-02-2012, 06:09 PM
David Paule David Paule is offline
 
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,070
Default Comparison To Old Cessna 180

Just to compare the exit areas to what my 1955 Cessna 180 has, here are some photos. The 180 has cowl flaps which are VERY effective both for cooling and for speed.

Here's the inlet area. Pretty large, eh? Also notice the diverging duct to the large air filter. Somewhat spoiled by the edge of the lower lip, though.



Here's the cowl flaps open:



And again from the side:



Here's the cowl flaps closed. Note the relatively small exit area and the position and length of the exhaust pipe:



Here's what they look like inside the cowl. Note that the sides are effective even when the flaps are closed, to channel the air into the exit:



As you can see from the cracks and doublers, there's a lot of vibration down there. For reference, this airplane has about 3,600 hours TT.

Dave

Last edited by David Paule : 06-02-2012 at 08:10 PM.
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  #360  
Old 06-02-2012, 07:25 PM
Bob Axsom Bob Axsom is offline
 
Join Date: Mar 2005
Posts: 5,685
Default I can see drifting that way

I have thought of cowl flaps of course and have discussed them with the likes of Tom Martin but I don't want to go there yet. The NLG structure and FAB requirements have to be considered. One option that might work is to retain the side view profile for ground operation and climb the pull the trailing edge up toward the fuselage to reduce the opening to limit the cooling air mass flow. I have approached that configuration with the long unvented cover and the two inch bump. The temperatures went up as I would expect but also under cylinder #2 the aluminized cover for the heat barrier was destroyed by heat from the exhaust I just patched that last night with a new piece of heat barrier - this is all that expensive $79 a package stuff from Aircraft Spruce. It is really good stuff but even it has its limits and I have to be careful. I don't know exactly what outlet configuration I need to optimize this for speed and safety - I am trying not to be too conservative but at the same time paying attention to what the airplane is telling me. The exhaust pipes are very close to the new forward shifted bumps that may cause me some problems as well - I may have to re-rig that whole tail pipe suspension system and that requires a lot of intricate work with my lower cowl baffling going right through it. I sound defensive I'm sure but I really appreciate your input and the real world example of what works for you on that airplane.

Bob Axsom

Last edited by Bob Axsom : 06-03-2012 at 12:56 AM. Reason: typo
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