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  #191  
Old 07-11-2014, 07:05 AM
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Brantel Brantel is offline
 
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Quote:
Originally Posted by DanH View Post
Follow up...this weekend I replaced the tiny Firgelli servo with a standard Ray Allen T2-7A.

Early in test I had noticed some freeplay developing within the Firgelli servo and expected it to strip a gear due to heat, which measured at about 160F in the servo location. However, it has been hanging in there since Christmas, so bravo to the designers.

That said, OSH is coming and I didn't want to chance a failed air door inbound from Ripon. The RAC servo is larger and more powerful, meaning the load applied in this app should only be a small fraction of normal capacity, i.e. low load on the gears when hot.
Dan,

Since Allan has brought an OTS solution to market using a similar actuator, did you ever tear that thing apart to see if it was a pending failure or?

As far as the RA T2-7A. How is that servo holding up?

By the way, thanks to Lars, I now have everything I need to make the piccolo tubes and gather some real data to answer your question in my other thread....
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Last edited by Brantel : 07-11-2014 at 07:08 AM.
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  #192  
Old 07-11-2014, 09:35 AM
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Originally Posted by DanH View Post
About 11.2; the EGT values are degrees ROP.
Dan, a question that is a little bit off the current topic but still of interest concerning the shrinking exit -- Have you evaluated the CHT's, TAS, fuel flow, Oil Temp, etc. while running in the same configuration as you posted in #190 while LOP? If so, what numbers have you seen LOP in that similar environment?
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  #193  
Old 07-11-2014, 01:24 PM
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Originally Posted by RVbySDI View Post
Have you evaluated the CHT's, TAS, fuel flow, Oil Temp, etc. while running in the same configuration as you posted in #190 while LOP?
Not seriously. No point. The benefits/shortcomings of LOP operation are independent of exit area.
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  #194  
Old 07-11-2014, 01:55 PM
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Not seriously. No point. The benefits/shortcomings of LOP operation are independent of exit area.
Understand about the exit area issues not really relevant for a conversation on LOP operations. I was just curious if you tested running LOP compared to ROP and what the delta was for the parameters mentioned.

Hope to talk with you again at OSH.
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  #195  
Old 01-01-2016, 12:34 PM
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Dan, i am designing a cowl flap for summer ops. How is the RA servo holding up?

I am going to finish my flight test phase before starting all the press/temp measurements under the cowl. I have all the instrumentation ready. I wont make any FWF mods until I am instrumented.
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  #196  
Old 01-01-2016, 07:50 PM
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Dan, i am designing a cowl flap for summer ops. How is the RA servo holding up?.
Doing fine. Arrange the door linkage to minimize gear load.
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  #197  
Old 02-26-2016, 01:43 PM
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Follow up report.

Started flying this oil cooler air supply duct in early 2013. The goal was to reduce the temperature of the air reaching the ducted oil cooler; measurements said the air picked up as much as 17F as it made its way from the cowl inlet to the rear baffle wall.



The duct dropped average oil termperature as expected, but I later decided to install a larger 10611 oil cooler anyway. I removed the above duct from the plenum lid at the most recent annual. As an experiment, it proved the theory, but isn't really needed now.

The 10611 with inlet and outlet ducting remains. Inlet is fed from the rear baffle wall. Cooler hangs on the motor mount. Inlet diffuser has a turning vane. The outlet duct sits flat against the firewall and terminates in the top of the cowl exit bell.





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Last edited by DanH : 09-06-2018 at 08:50 AM.
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  #198  
Old 06-01-2017, 08:36 AM
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I happened to be looking up some old data from past tests, and just out of curiosity, ran the numbers for coefficient of pressure as defined in NASA CR3405, to wit:

(plenum static pressure less freestream static) / freestream dynamic pressure

The three measurements made in level flight were done at partial power, in each case just enough to maintain the desired 120, 140, and 160 IAS. The resulting true airspeed (NTPS method) is shown here. A Cp in the high 0.8 range is very good.

The curiosity point was the effect of propeller outflow at full power and 100 IAS, given a constant speed BA Hartzell, with low Vi/Vo inlets moved outboard as far as possible, and in close proximity to the blade. Cp turned out to be 1.17 when calculated using 100 knots for the dynamic pressure. The difference between Cp in the 0.8's and 1.17 is almost entirely due to high velocity air from the prop, meaning prop outflow is a very large part of cooling power in a steep climb.

There is a probable prop outflow contribution in the level flight values too, but not nearly so much, as the power settings were quite low, and the difference between prop outflow and aircraft TAS gets smaller as velocity goes up. It might be interesting to get some pressure numbers with the prop stopped, for comparison.

Note, these measurements were taken several exit iterations in the past....a small fixed exit ending at the plane of the firewall, the smallest in the very first post.

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Last edited by DanH : 07-17-2018 at 06:12 AM.
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  #199  
Old 06-02-2017, 06:04 AM
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Default Let's look at it another way...

Dan,

I appreciate the effort you have contributed to this project. I'm no engineer and I find it difficult to follow your logic so I looked up a video which explains it in terms that I can understand. Maybe this will help others as well.

https://www.youtube.com/watch?v=RXJKdh1KZ0w
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  #200  
Old 06-02-2017, 08:03 AM
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Thanks Ron,

Like you, I had a tough time following Dan's logic...but your post very much helped me get my head around some of the technical issues. The explanation of the Rockwell Retro Encabulator put everything into easy perspective.

Thanks,
Ackselle
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