Cameron's Christen Eagle II Build Thread

Discussion in 'Christen Eagle' started by Cameron, Feb 8, 2014.

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  1. Jul 9, 2018 #1221

    Cameron

    Cameron

    Cameron

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    Sure Eric, let me know what you need. Looks like you've about got it figured out though.

    Nope, no air filter. Extras and Pitts come from the factory that way. I've got a buddy with 1000 hrs on his IO540 in an MX2...all with no filter. If you're based on a dusty grass or dirt strip, it may not be such a good idea.
     
  2. Jul 9, 2018 #1222

    Gmovies

    Gmovies

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    Great work Cameron. I've got a long list of items to improve on my plane and I'd love to do some cowl mods like this. I'll certainly come back here to study your efforts when the time comes.

    What was your overall MPH gain with all the inlet/exit mods on the cowl?

    What was your MP gain from the ram air engine inlet?

    Thanks,
    Paul
     
  3. Jul 9, 2018 #1223

    Cameron

    Cameron

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    That's a hard answer for me to give you Paul. I think back when I sealed the baffling behind the flywheel and added the exit bell, I reported a 7mph increase. I now seriously doubt that claim (as well as a few others I've made). That was back when I was using indicated airspeed as my comparison tool. I did a test flight before the mods, and I recorded max IAS. That was late September ish. Then, a month or so later, I made another test run with the new baffling and exit bell, in cooler temperatures and reported a 7mph gain. What I realize now, is a lot of that gain was due to the cooler temps and I really don't know how much of a gain there was. If I had to guess...maybe 3-4mph, but that's all that is....a guess. If I only knew then, what I know now.

    But, I have learned from my mistakes. My last round of cowling mods has resulted in a 5mph gain, 3mph due to the ram air, and 2mph from the oil cooler inlet. This data was collected during three flights, all on the same day. One with the stock config, one with the new ram air scoop, and a final one with the ram air scoop and the oil cooler inlet. During each flight, I flew two GPS triangles, then used that, and a spreadsheet that I found that calculates TAS, winds aloft and direction based on your GPS tracks and ground speeds. I flew two GPS triangles on each flight, and averaged that data to come up with those numbers above. Long story short, I feel pretty confident in them. In another year...I may have learned more and I may not feel as confident in them?

    As far as how much my manifold pressure increased, it is right at 1" vs. the stock setup, maybe just a touch more. At WOT, straight and level, I usually get .5-.75" higher than ambient. Another Eagle owner now has this same ram air setup and he is getting very similar results

    I did run across some data from last year that I collected soon after I got N216HP flying where I did use GPS triangles (although only one per power setting) and I had a max TAS of 181mph. That was without spades, and without a sighting device. I don't know how much they slowed me down, but I'd imagine that they did a little bit. On my to do list is to do some more GPS triangles at the same density altitude as a year ago to see what my cumulative gain over the last year has been. I suspect its going to be 7-8mph, but we'll see.

    Someday, I still plan on closing up my cylinder cooling inlets, while also improving their shape. One of the big things that I've learned in all of this is that the leading edge radius needs to not be small and sharp.....like the stock Eagle cowling inlets.
     
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  4. Jul 9, 2018 #1224

    cwilliamrose

    cwilliamrose

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    If the air is being drawn in a good inlet radius is very important. I'm not sure the same is true with ram air unless there's an entry angle causing the flow to trip. I did some work on velocity stacks for a marine application and the flow bench basically told me bigger is better but only small loses occurred if the stack's bell was incomplete or was interrupted by the wall of the plenum -- this was once I had a generous radius on the bell.
     
  5. Jul 9, 2018 #1225

    Cameron

    Cameron

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    That's interesting Bill. Sounds like you've got to do some cool stuff in your career.

    I made a few different ram air inlets with a sharper radius. I got almost the same amount of MP, but I got a lot more needle bounce on my MP gauge. The engine also didn't seem to run as smoothly. By the way, my MP gauge does not have a restrictor in the back side of the gauge. It kept getting clogged up, so I just took the screw out. I found with the larger radius like I've got now, the needle is rock steady and the engine runs smoother than it does if it is bouncing around. I took that to mean that I was getting a more steady flow, but not necessarily more flow. I also took it to mean that a smaller radius did something to make the airflow going into the inlet more turbulent. My conclusions may be way off but suffice it to say, my engine is happier with the larger radius.

    Somewhere along this path, I found the attached article about inlets and their shapes.
     

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  6. Jul 9, 2018 #1226

    garyg

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    Cameron,
    So from the looks of your intake, the exterior is a fixed bell intake and then has an angle up inside the cowling toward the fuel servo that is attached by a flexible hose (turbo hose?) between the external bell and the servo.

    What is the exterior bell diameter and the servo diameter? Are they the same?

    I am thinking of something like this in the link (obviously not my plane) as it has the fixed exterior bell as a opposed to a horn that goes through the cowling that would need a seal. I am not sure how to make a bell of either sort. Is there a place to buy them?

    https://www.airplane-pictures.net/photo/887476/lv-x562-private-pitts-s-1-11b-special/

    gary
     
    Last edited: Jul 9, 2018
  7. Jul 9, 2018 #1227

    cwilliamrose

    cwilliamrose

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    Cameron,

    That article would have been handy to have back when I was doing the flow work. At the time I was somewhat limited by the process I used to create the tubes which was to flare them over a shop-made tool in the hydraulic press. They were 2"OD aluminum tubes and I ended up with an approximately 1"radius bell (the tool was made 'by hand' in the lathe) that did not go much beyond 45°, certainly not well past 90° like the test parts in the article. If I went any farther the bell would crack and that was after a bunch of anneal cycles to keep the material soft.

    I have some photos of the parts that I could post to show what I ended up with.
     
  8. Jul 9, 2018 #1228

    Cameron

    Cameron

    Cameron

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    Gary,
    Yes, the exterior bell mouth is fixed to the cowling. It screws on using the same holes as the original filter cover used. It does not attach to the servo though. If you know someone with an Eagle that you can look at, this will make more sense, but on an Eagle, the cowling houses the filter and the airbox. At the aft end of the airbox, there is a 7" or so diameter piece of inner tube rubber with a 2" hole in the middle of it. On the fuel servo's forward flange, there is a flanged tube that is mounted to it that points forward, and down a little. This tube protrudes through the hole in the inner tube rubber sheet. The rubber sheet allows the engine to move independently of the airbox. My ram air scoop gets rid of the filter and the tube (3.13" ID at its smallest) expands as it protrudes farther into the airbox until it almost touches the rubber sheet. At its aft most point, that tube is about 4.75" in diameter. This expanding plenum is there, in theory, to slow the air down and convert dynamic pressure into static pressure. This high static pressure area is where the tube that is bolted to the servo gets its air from.

    I haven't seen a place to buy an intake bell but I'm sure some aftermarket car or boat place makes them. I had to make all of my own stuff.
     
  9. Jul 9, 2018 #1229

    taff

    taff

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    Not trying to steal your thread Cameron.

    I am trying to do something similar. Someone here directed me to PJ Motorsports, they make velocity stacks.
    I contacted them and they quoted me to make a custom size stack $125 to make the mandrel and $80 to spin the stack. I think I need the filter set to attach also.
    Anyway a couple of pix of what I am thinking of.
     

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  10. Jul 9, 2018 #1230

    PittsDriver68

    PittsDriver68

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    Once upon a time I did an engine conversion and wanted a bell-ed intake to the fuel control. I found a Mooney 201 airbox in a salvage yard. Roy Lopresti bolted a nice bell to the front of the fuel control and riveted it to the back side of the airbox behind the air filter. I took that bell and almost duplicated what Lopresti did. Bolted it to the front of my RSA-5 and riveted it to my custom airbox.

    You might be able to do a similar adaptation.

    Best of luck,

    Wes
     
  11. Jul 10, 2018 #1231

    cwilliamrose

    cwilliamrose

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    Below are photos of the parts for the prototype fuel injection system I worked on. I was not on board with the plenum design, we later did a lower volume version which was better in my eyes. The plenum, two-piece intakes and the fuel rails are fabricated parts. One of the things the prototype was designed to test was the length of the velocity tubes which is why the intakes were made in two pieces.

    BPM V-12 Induction System Parts 1.JPG BPM V-12 Induction System Parts 2.JPG BPM V-12 Induction System Parts 3.JPG
     
  12. Jul 10, 2018 #1232

    Cameron

    Cameron

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    Cool stuff Bill.
     
  13. Jul 10, 2018 #1233

    Gmovies

    Gmovies

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    Very good Cameron. Sounds like your data should be pretty reliable from here on out because SCIENCE!!!
     
  14. Jul 13, 2018 #1234

    garyg

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    Cameron,

    Thanks for the explanation/description. I think I understand. Took me a couple of reads but the internet was no help with any images. I have been thinking/investigating..... On cars, I am pretty sure "the expanding plenum" exists to quiet the engine down. I have a V8 Dodge Dakota where the previous owner removed the plenum box from on top of the engine and put a straight K&N system on it and the intake is louder than the exhaust in the drivers seat (and it has no mufflers). At least on cars, I have no idea that they exist other than for noise. The article shows a picture of the plenum after the intake but I didn't see any reference to that design at all. Maybe I missed something?

    I have a AFP FM300 and it has a intake diameter of 3.75 inches. I can find turbo velocity stacks of 3.0, 3.5, and 4.0 but not 3.75. Like these on ebay:
    https://www.ebay.com/bhp/4-velocity-stack


    I can use turbo hose reducers to go from either direction:
    http://www.turbohoses.com/Transition.htm

    The paper doesn't address this, but do you think it is better to go from big to smaller or smaller to bigger, if there isn't a plenum at all??

    gjg
     
  15. Jul 13, 2018 #1235

    Cameron

    Cameron

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    Those velocity stacks look nice. Try to find a flexible hose to connect it to your servo. For one iteration of my ram air system, I was going to use one of those turbo hoses so I ordered one. When I got it in, it wasn't very flexible at all so I abandoned that idea.

    I kind of doubt that there will be much of a difference either way, but my gut instinct is to say that going from smaller to bigger on the hose diameter adapter would be better if there is a sharp transition in the adapter between the two inside diameters. But, if the transition from bigger to smaller is fairly smooth, I'd say that going from bigger to smaller would be better.

    But this is all a guess? If you really want to find out, try it both ways....
     
  16. Jul 13, 2018 #1236

    garyg

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    Cameron,

    I am not sure I will be able to try multiple versions as we are going to try to build the velocity stack right into the cowl. Well that is the thought anyway. With such a large bell on those stacks, I am wondering how it will work out. The servo is 8 to 10 inches back and I dont seem to be able to orient it any direction but down and I need to make the cowl go way down to get past the fuel lines. If I created a plenum, then a transition wouldn't mean much but then what does that mean for ram air? Is there a difference between cold air intake coming out of the front of the cowling and ram air? Good advice on the turbo hoses. I seen a couple but never checked on the stiffness. Since I have a lot of distance, maybe it would be more forgiving? I have a couple of samples close by, I will take a closer look.


    gjg
     
  17. Jul 13, 2018 #1237

    Cameron

    Cameron

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    I don't know that a plenum is even really needed. I have a friend with an MX2 in which he says he sees 31" of manifold pressure. Keep in mind that he's going a lot faster than me too. But on his airplane, there is just an intake bell that starts out at around 4-5" diameter, and gradually necks down to the diameter of the servo. The duct just ends a 3/8" or so in front of the servo, there's no seal, or direct connection between the duct and the servo so the engine is free to move. I tried a similar setup on my airplane, but the duct leading to the servo had to have a couple of bends in it. I can't get a straight shot at it without major cowling mods. I also don't have that much for-aft space. It worked about as well as my current setup, but no better. I also didn't like the idea of air getting into the lower cowling that hadn't passed through the cylinders or the oil cooler. But, I can't argue with how the MX2 setup works, or its simplicity.
     

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  18. Jul 13, 2018 #1238

    garyg

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    I assume that is your rendition of the intake. Looks good (both the rendition and the setup). Clarifies my imagination. I have been going back thru the thread to see if I missed something like that but I am only like on 35 or 40......much of which I already read but don't recall anything specific until I look again. That is a hefty angle but it makes the cowling look great. . Mine is hitting, if going straight, right at the bottom of the bowl lip, with the center about 2 inches up it. The S1-11 plans called for a big box hanging off the bottom of the cowling for a normal intake so I won't be lower than that but so far it looks more obnoxious to make. Interesting on the MX. I have some pictures that Don from AFP sent me where a MX installed a servo like mine 90 degrees counterclockwise. If I did that with mine, it would just stick a different fuel line under the servo with the same result. A gap probably wouldnt hurt much at all over a short distance.

    gjg
     
  19. Jul 15, 2018 #1239

    Cameron

    Cameron

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    Finally got the nerve to try out the aluminum tailwheel spring on my airplane. It’s got a higher spring rate than its steel counterpart. I like the ride and landing characteristics better but I think the spring rate could stand to be a little less. I may make another one that is a little thinner just to try. It will also be lighter that way.

    Weight wise, I took 1.76 lbs off of the tail. Moved the CG forward by .23”.

    Only time will tell if it will hold up. Rob is having good luck with his.

    I’m monitoring it closely for bending and cracking.

    IMG_0016.jpg
     
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  20. Jul 15, 2018 #1240

    crankyklingon

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    Sure looks clean and sporty on there. Have you tried it with two people in the plane yet?
     
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