Kent's Long-EZ project

[Kent Ashton]

43 minutes ago, Countach74 said:

Kent- Really enjoy reading about all your experimenting!!!

That's sweet!  Thanks.   😍   (ha!)

[Kent Ashton]

A chap on FB asked about how to do an induction leak check.  I saw this interesting video on how to do one in conjunction with a compression check.  Essentially, you are pressurizing the cylinder and cracking open the intake valve which burps the pressure into the intake, checking for a leak with soapy water.

https://youtu.be/CfG4QGv-r64

Be careful with that prop.  I visually position the prop to TDC using marks on the flywheel and hold on for dear life as my wife slowly opens the compression gauge.  Usually there is no tendency for the prop to turn and I can wiggle it a bit around TDC to get the highest reading.

[Kent Ashton]

Other induction-leak finding ideas:  Spray carb cleaner or propane from an unlit torch around the joints but, of course, the engine has to be running.  Idle will increase.

[Kent Ashton]

I see that a chap on FB is trying to diagnose cooling with a wireless manometer (pic 1, $118).   He got a differential of 3.86" (pic 2) which is 30% less than the Lycoming-recommended 5.5" for an O-320 so it's no wonder the engine runs hot.  The chart (pic 3) looks official but I don't know what it comes from.  I would not have used the small piccolo tubes that came with the kit (pic 4).  I would have used longer ones (pic 5) and mounted them just above and below the cylinders--seems more accurate that way, and I would have plumbed the manometer to the cold side of the firewall or cold side of the baffles.

He says he has only 1" from the top of his cylinders to the cowl.  Visualize: air is blowing out of the fins (at what velocity--100 knots?).  One inch later it impacts the cowl and has to make a 90° turn.  What direction does the air go?  Aft, off to the side, towards the engine centerline?  Who knows.  My guess is that the small space is creating back pressure and not allowing the cylinders to evenly pass air through the fins.  Sharp turns, turbulence and nearby surfaces create cooling drag.

Here is my gripe with Facebook:  Most of the pics below are in the chap's thread but you would never find them with a search and they do not show up unless you click on every "view 8 more replies".  It is a dog-ass way to display and archive good information and a shame the canard community is divided among 4-5 FB sites.   😞

tags: cooling manometer pressure differential piccolo tubes

[jridge]

I'm with you Ken.  Google searches find none of this stuff on Facebook.  And in a few months, to see any older posts, you'll have to scroll and scroll and scroll downward in the FB posts.  Don't know why everyone likes FB so much.

[Kent Ashton]

Saw a fellow on FB asking where to buy one of the old Brock gas caps (pic 1).  Actually, the one he has can be cleaned up, o-rings replaced, and be as good as new.  It was a nice light, inexpensive cap and replacing them is a chore.  However, they can be made (pic 2).  I did not hollow-out the inside like the Brock cap but it was not too hard to turn down a piece of flat aluminum.  Grind a small bit to make the o-ring groove.

[Kent Ashton]

Saw an article about this chap (video) who is pushing a program to train pilots against synthetic aircraft for the military using a Berkut.  Interesting.  It seems the synthetic airplane is projected in the Berkut pilot's helmet and they fight it out in the air.  I wonder who is "flying" the synthetic airplane?  The Air Force is 2000 pilots short and having a hard time training enough people fast enough. 

I don't know why they just can't use simulators which are fantastic these days.  In about 1977 I went through an air combat program run by Vought in Dallas.  Vought had set up two spheres with a cockpit in each; the opposite aircraft was projected inside the sphere of the other.  They could set us up line abreast or head-on and we would go at it.  There was not much else to it except a crude ground projection and the opposing aircraft.   You would maneuver for a gun or heat-seeker kill.  An instructor could sit in a chair beside your cockpit and reverse the last 10 seconds of a fight and show you where you went wrong.  Even that was great training (and fun) for basic close-in air combat. 

 

[Voidhawk9]

Being involved in flight simulators for various purposes for many years, I agree. There seems to be a general opinion from many pilots that simulators aren't useful for anything beyond procedures. But that hasn't been true for many years!

We've come a very very long way from Link trainers. 😏

[Kent Ashton]

Saw this question on a FB page.   It's a common question by people new to experimentals.

Quote

Ok another discussion item. Hypothetical of course.
You are a non-builder and buy a Long Ez. Have lots of fun one day some idiot taxis into your plane and takes three feet off the end of your right wing. Lots of damage. Your pretty handy and the builder gave the construction manual to you with the plane.
So you find all the data and materials you need and build a complete new wing per plans. You documented the entire process.
Now who signs off on the wing. An A & P?. What do most A & Ps know about moldless composite construction. If they do who certifies them ?
What would be the process to get this plane legal again?
Can one say "I'm an A & P, I built a moldless composite airplane and I'm proclaiming myself an expert so I can sign off on this repair.

Anyone can work on a Experimental airplane, even one you did not originally build.  You can rebuild a wing, or an engine (even one that is allegedly "certified" but that's another subject).  A similar question often heard is "where does it say anyone can work on a hombuilt airplane?".  It is fun say "nowhere" and witness their disbelief.  Nevertheless, under 14 CFR §43.1(b)(1), we enjoy freedom from regulation over how we maintain, rebuild or alter our aircraft.  https://www.law.cornell.edu/cfr/text/14/43.1

However, not so fast.  We ARE governed by Operating Limitations issued for the particular airplane that levy an annual condition inspection requirement by an A&P or person with a Repairman Certificate for the airplane, as well as say how to put our aircraft back into service after repairs, so it is not exactly true freedom but reasonably close.  Point is, the chap above is free to rebuild his wing himself, re-enter the aircraft into Phase I testing, and when the tests are complete, certify himself that the airplane is safe for flight.

To me, this is the true reason for owning an Experimental.

 

[Voidhawk9]

That's certainly a huge appeal.

I'm involved in the local aero club (part-time instructor - when not under the present lockdown), and they have an aging fleet with many known issues that they cannot do anything about or that would cost far more than they can afford. If the aircraft were experimental, first - well they wouldn't be able to use them in their business. Second, you could readily solve and mod as needed.

One of the reasons GA is dying here in NZ is the cost of new equipment is far outside the budget of most operations, and the aging fleet with all the associated issues is a turn-off to many prospective pilots.

Edited March 30, 2020 by Voidhawk9

[mquinn6]

I understand the FAA is working on a method to help keep these older GA planes "alive" by making new (affordable) equipment that we use in experimental - to be used in the GA aircraft (like glass panel and autopilot were examples that were given).  I think this is one of the articles about it -  https://www.faa.gov/news/updates/?newsId=88746  

I will look thru my notes to figure out what the codename for the project it and will be able to google it and get back...  

[Kent Ashton]

Here are some photos posted by Terry Schubert elsewhere showing an oil flow check on an EZ.  They are interesting to think about; these are just my opinions.  In pic 1, pressure is pushing the surface flow away from the NACA.  It is said the action of decellerating the flow [inside the cowl] increases pressure which I would seem to resist inflow.  I have seen people add wedges (pink) to better-capture the flow.  They say the wedges work but perhaps the pressure buildup is aggravated by insufficient exit area from the cowl.  

Pic 2 is about what you usually see.  I believe pic 3 is a Klaus Savier (Lightspeed) preformed NACA inlet.  The Savier idea is nice but it will make it harder to work on firewall stuff.  Maybe a removable inlet cone would be better.  In pic 4, I doubt the inlet cone does much good.  NACA tests said the airflow needs about a 7° or less divergent angle to stay organized which is why a NACA inlet has such a long, shallow floor,  Here, the air is probably in-flowing at 100+ knots.  It is probably not going to turn the corners of the cone.  I put a partial inlet cone in my Cozy--pic 5, the aluminum piece above the inlet--I couldn't see much difference.

I am no Dr.-Ing Hoerner but one thing I always remember is that air is heavy and it's going 150kts.  It wants to keep going in the same direction.

[Kent Ashton]

Just reading the report on the Lance Hooley jet EZ accident.   http://www.kathrynsreport.com/2020/04/aircraft-structural-failure-hooley-jet_8.html

There is not much I can get out of it except there was a dry place noted in the layups and a possible flutter incident earlier.  It seems to me he was expecting a lot out of the airplane.  I have always been a little nervous flying either an F-4 or a Cozy at high Q, or high dynamic pressure--read of too many bad things happening there.  The little I know about Q is that it increases with the square of the velocity.  You go twice as fast, your dynamic pressure is 4 times higher.  Goodness knows what happens to lift, drag and the other forces on the structure.

When the F-4 was new, Operation Sage Burner intended to set a speed record.  The F-4 was not very stable and had pitch dampeners to increase pitch stability.  During one of those attempts, the dampeners did not work and the airplane got into a pitch oscillation and broke up.  https://youtu.be/bQ6IhkxoNz8    In the video, you can see the airplane begin a small pitch oscillation and breakup shortly thereafter.  I used to have a picture of the engines flying out of the wreckage.

Here is the usual sequence:  The F-4 had hydraulic flight controls with little natural feel or air resistance to stick movement.  A "bobweight" was installed in the tail and linked to the stick to make the airplane feel normal.  When you put positive G on the airplane, that G on the bobweight acted through the linkage to pull the stick forward as would happen in most airplanes.  This gave a more natural pitch feel akin to air loads on the horizontal tail but the stick was still sensitive.  When even a moderate positive G was put on the aircraft _suddenly_, the bobweight suddenly became heavier and suddenly pulled the stick forward as it was wont to do.  If a pilot then over-corrected by making an overly-large forward stick input just as the bobweight was "helping" to apply forward stick, that might put negative G on the airplane.  Then the reverse happened: the pilot might correct the negative G with aft stick just as negative G on the bobweight was helping to apply aft stick.  A PIO (pilot induced oscillation) was often the result.  All this was supposed to be controlled by a bellows which sensed airspeed and dampened pitch inputs but in the Sage Burner crash, the pitch dampener was inop.  We were mainly taught never to "snatch" the airplane--i.e., make a sudden stick input, even with the dampeners working, and to hold the stick firmly when maneuvering with one's forearm braced on one's leg.  After a while you got used to it

However in one case an instructor and student WSO briefed an air combat training sortie with another airplane but the other airplane aborted after takeoff.  The IP told the student they would go out to the practice area and he would demonstrate the high speed characteristics of the Phantom.  Sometime during that demo, the pilot got into a PIO that put around 9-12 Gs on the airplane.  When they returned, the engines were still running but they had broken away from the engine mounts and were retained on the bottom of the engine bay!

So that's why I am generally content to putz around in my little homebuit and not explore extreme corners of the envelope.  🙂

 

[Voidhawk9]

Thanks for posting that, I have wondered about that accident for some time.

My take away is that any flutter event can cause damage to the structure (even if not readily detectable) that may weaken it. Also that if it happens once, it can happen again, and maybe much worse. 😧

[jridge]

Kent-

Interesting story on the old Phantom II. That airplane was quite a looker.  I take it you were in the USAF?  Where based and what timeframe?

[Kent Ashton]

A while back I mentioned that the Rotec line of throttle body injectors looked pretty nice.  https://www.canardzone.com/forums/topic/18661-kents-long-ez-project/?do=findComment&comment=66841   But I was just reviewing this long thread on the Vans Air force site with guys complaining about problems and tech support.  http://www.vansairforce.com/community/showthread.php?t=114648    The thread is getting a bit dated now but I suggest reading it if you're interested in a Rotec.  Maybe the problems have been resolved.   The OP on the Vans thread, Phil Camarda, has a lot of experience with EZs and has a pretty good website himself.  I imagine he'd be a good person to talk to about the Rotec.  http://longezpilot.com/index.htm

 

Edited April 10, 2020 by Kent Ashton

[Kent Ashton]

Pic grabbed from a FB page.   Builder says his engine is a UL520.  I could only find a UL390 (pic 2).  It is really a blocky-looking cowl.  The Lycomings can use an 8" prop extension;  I don't know if the UL engines will tolerate that.  It appears he could have flowed the cowl into the prop a little better and avoided the rather sharp corners.  He might have eliminated a lot of the cowl volume below the cylinders.  The intake tubes are on top.  No need for a lot of space under the cylinders.  If he could widen and flatten that oil pan, or exit the exhausts with a simple 90 deg turn, I think it would reduce the cowl volume by several cubic feet.

I predict those small cooling exit holes will be totally insufficient

Edited April 30, 2020 by Kent Ashton

[Voidhawk9]

Looks like the front-end of a simple-design LSA. Not at all optimal for a trailing edge, there will be a lot of separation there.

[Countach74]

That is one Fugly cowl!!!

[Jon Matcho]

FWIW, the execution appears to be rather good.  The design just needs some help. 🙂

[Voidhawk9]

7 hours ago, Jon Matcho said:

FWIW, the execution appears to be rather good.  The design just needs some help. 🙂

Nailed it.

[Kent Ashton]

Almost 29 years ago (wow!) , there was a fellow who built canards for hire that were junk  See "Beware" here  http://www.cozybuilders.org/newsletters/news_35.html#beware   That was an unusual case.  So I was puzzled by a controversy this week involving a well-known parts seller.  It was never fully explained in the back-and-forth but it appears to me the seller delivered some substandard parts and got testy when the buyer complained.  The threads on the NG pivot (pic 1) are clearly substandard and the NG fork (pic 2) looks as rough as heck.  That's a highly stressed part.  It ought to look very smooth--polished even.  Sharp edges should be rounded.  FWIW.

 

[Barry]

That threading wouldn't be acceptable for non-aircraft related uses.

 

Both parts are junk.

Edited May 2, 2020 by Barry

[Anthony P]

Where in the world do you guys see threads???

I see a shaft that was spun in a bench vice!  😀

[jridge]

Whole thread can be seen on the Canard-Aviators Google.io group....

https://canardzone.groups.io/g/canard-aviators/topic/vendor_report/73376232?p=,,,20,0,0,0::recentpostdate%2Fsticky,,,20,2,0,73376232