8.99 – Cracked wheel

This entry is part 8 of 8 in the series 08 - Wheels / Axles

During the annual condition inspection this year, I was tightening the three screws which hold the brake disc onto the wheels.  One of them was not tightening.  I thought that maybe I had stripped the head.

Turns out the threads in the wheel are what got stripped.

I called Matco to see if a helicoil was an approved fix. While waiting for a callback from an engineer, I pulled the wheel because whether I could use a helicoil or had to replace the wheel, it was going to have to come off anyway.

Once it was off, I looked at the hole and decided that replacement was the only option.

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The crack around the hole makes fixing it a non-starter.

When I spoke to Matco, they said that if I sent them the wheel that they would replace the half with the crack for $90.

So off it went.

13.4 – More Static Port Fun

This entry is part 67 of 67 in the series 13 - Electrical / Instruments


Well, that didn’t work very well.

Currently I’m back to my original design with some minor changes.  The original static port was bonded in place.  My new one is held in place with an AN bulkhead fitting nut. And instead of .75″ in diameter, it’s 1″ in diameter.  I adjusted the height of the dam behind the opening and by doing low altitude passes over the runway at high and low speeds, I have got the altitude error down to about 10′.  I still get the altitude “drop” when I rotate at takeoff, but the rest of the time, the error appears to be minor.

So I’m calling it done.


The other day during takeoff, I just happened to glance at the altimeter.  Normally, the altimeter is not something you’re concerned with during the takeoff roll.  But just before the wheels left the ground, I noticed that the altimeter was reading 50′ lower than the field elevation.

After reviewing the flight data for the past 30 or so flights, I discovered that the altimeter would go from the field elevation when the plane was stopped to 50′ – 60′ below at 70KIAS.

I thought that I had the static port error taken care of.  But once I saw this, I did a constant altitude, increasing airspeed test.  The GPS altitude should remain constant, but it didn’t.

After thinking about it, I thought that the angle of the fuselage may be a factor.  All the other planes that I’ve looked at have their static ports located where they are perpendicular to the airflow.  In some cases where the fuselage tapers back towards the tail.  But never at the front where the fuselage width is increasing. I think that’s because in that position, the static port could be subjected to ram air.


The location of the static port on a Velocity is where the fuselage tapers to the nose at a 15 degree angle. I think that the airflow may be affecting the pressure subjected to the port. Now it’s possible the boundary layer may factor in here but as I’m not a fluid dynamics guy, I really don’t know.

But here’s my idea. If I could match the angle of the static port to that of the airflow, I may be able to get a null pressure area.


So I put some 1″ aluminum stock in the lathe and got to work. While I was at it, I decided to make another change.  The current port is bonded in place.  So changing it is a bit of a pain. The new static port will be held in place with a nut from a bulkhead AN fitting.

Here’s the new static port:IMG_20180524_180133



And here’s where is gets interesting:


I have created 15 degree “wedges” that will allow the port to be perpendicular to the airflow.

I have absolutely no idea if it will work or not.  After the baby hurricane makes landfall on Memorial Day and moves on, I’ll install it and find out.

Still can’t fly, but I got the static port installed.

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It is oriented to be plumb and aligned with the direction of flight.

7-99 Sealing the Nose Landing Gear

This entry is part 39 of 39 in the series 07 - Landing Gear

One of the biggest comfort issues with the Velocity is heat (or lack thereof). There are numerous methods of increasing the amount of heat entering the cabin.  I won’t go into that here.  Beyond that, the reason for lack of a warm cabin is that the retractable gear Velocity’s are drafty.

In a Velocity with retractable gear, there’s a big opening in the front for the nose gear.  While there are doors which cover this opening when the gear is retracted, it’s not airtight. And when the gear is extended, the volume of air entering through that opening is impressive.

The area under the doghouse at the leading edge of the canard is open to the nose, and all of the air entering the opening for the nose gear. This is the primary path for outside air into the cabin.

Second, that nose gear opening extends aft of the canard bulkhead. Which means air is infiltrating into the keel.  Directly above this opening is where the elevator push-pull tube exits the keel into the cabin.  Some people have fashioned boots to seal the area around the push-pull tube to block this path of outside air entering the cabin. But even then, there are numerous paths from the keel to the cabin.

The final path for outside air getting into the cabin is through the openings for the rudder pedal push rods which go through the canard bulkhead to the bellcrank.

When I extend the landing gear, I am greeted with (literally) a blast of air.  In the summer, it’s welcome.  In the winter, not so much.

Blocking the primary air path has been solved for quite a while by creating an upper bulkhead between the leading edge of the canard and the top of the nose. What I will be addressing is stopping the air through the second and third paths.

For the rudder pedal pushrods, the factory has been using a box which covers the area on the forward side of the canard bulkhead.  I couldn’t use this approach as my oil cooler exit duct if closer to the canard bulkhead than the plans call for.  Fortunately, fellow builder and problem solver Andy Millin came up with a solution.  Grommets (which I would call small bellows type seals). One for each pushrod. These are available from McMaster-Carr for about $15 each.  The part number is 9280K62.  Andy says this can be done with the canard in.  My canard was out for service which made the job much easier. Once I had removed the pushrods and bellcrank, I had to enlarge the holes to accommodate the grommets.This created a bit of a challenge because a hole saw would be the perfect tool.  But the rudder pedals were in the way from the cabin side and the oil cooler exit duct was in the way from the nose side.So here’s what I did:  I took the hole saw bit and put a ratcheting wrench on the hex shaft.  Then a large area washer went over that to give me a larger bearing surface. Wedge the whole thing in position and start turning the wrench.  In just a few minutes, I had two perfectly sized holes.

Hole saw rig:

IMG_20180328_075112 Cutting the holes:


The next task was creating a flat surface for the grommets. Now I could have just globbed on the RTV and stuck them in place. But the holes where close to the edges and I didn’t want any chance of air leaking through.  So I took a piece of ¼” aluminum stock that I had, waxed it up, applied some Resin Research epoxy with cabo around the holes and clamped the aluminum in place. The next day, I removed the aluminum, cleaned up the holes and then I was ready to install the grommets.

Ready to install the grommets:

I could have used screws to install the grommets, but as there is very little tension on the grommets, I used RTV.  Once the RTV cured, I cut the tips of the grommets off and reinstalled the rudder pushrods.


Grommets installed


View from the cabin side:


Rudder pushrods installed


Blocking the air coming through the keel has always been a challenge.  Some have made a boot similar to those found on manual transmission shifters. Over the years, I’ve considered a couple approaches.  The one that I was most hopeful of was similar to what is found on many automatic transmission console shifters. Basically a slotted housing with a flexible, wide area washers.  But because of the size of the opening, I would need multiple wide area washers with slotted openings and that would require guides on the housing.  If I was still in the building stage, I would have explored that further.  But I wanted to get back in the air.  So I went with Plan A.

I had thought about this approach while still building but I abandoned it to get finished. Basically, it’s a pair of supports with baffle material being the final seal against the pivot shaft.  The disadvantage to this method is that there is a gap while the gear is in transit. But when the gear is up or down, it should provide a very good seal.  I took measurements and built up the concept in CAD to get the dimensions and validate the concept.

Here’s what it looks like:


There are two rigid components.  The upper (canard) and lower (floor) brackets.  One thing I did NOT want was one of these coming loose and preventing the gear from extending.  So on the canard bracket, the two center mounting holes go through the canard bulkhead with MS27039 screws and locknuts. Since there’s no way to do through-hole screws on the floor bracket, I used 5 T10 screws.

bulkhead floor

The material for the brackets is 1/8” aluminum.  This is a bit of a challenge to bend, but I didn’t want any possibility of it deforming.  The flexible material is standard 1/8” baffle material which is cut trial-and-error to get a tight fit against the gear leg in the retracted and extended position.

NOTE: I do not think it’s possible to install these with the canard installed. Also, the brackets are a little oversized.  They will require some trimming to fit.  This is intentional since you want a very tight fit to the sides of the keel.

In the first version, I attached the baffle material to the bracket using pop rivets. But I noticed buckling.  So on the second version, I used 1/16” aluminum stock as a backing surface.

I planned on using RTV to fill any gaps between the brackets and the keel but decided to try it out before doing that.

Gear up.  I could have made the floor baffle a little tighter, but then I would run into binding when the gear was down.


Gear down.  Very tight fit all around.  And that’s when it is really needed.


View from inside the keel with the gear up.  A little bit of gap here, but I’m more concerned with when the gear is down.


On the first flight after installing, when I lowered the landing gear, I was a little alarmed at first because I thought the gear wasn’t extending. There was no familiar rush of air when the gear was extending. Before, I could always feel a strong breeze around my lower legs.  Now, the only indication that the gear is down is the drag of the gear and the wind noise from the gear hanging out in the air.

I’m going to have to wait about six months for cold weather before I can claim total success. But at this point it feels promising.



Electronic Ignition

This entry is part 49 of 50 in the series 12 - Engine / Propeller

One of the things I was planning on when I started building was to install electronic ignition.

If you understand aircraft engines, please skip ahead “RESUME HERE” mark. 😉

The spark on aircraft piston engines is provided by a magneto. This is similar to the distributor on an (older) car engine.  The difference is that a magneto is effectively self powered. It generates the spark without any outside power required. That’s why an airplane engine can run even if the master power switch is turned off.

There are two magnetos which are connected to two spark plugs for each cylinder. There are two reasons for this: 1) redundancy and 2) two sparks burn the fuel mixture better than one.

There is also a big drawback to magnetos.  They don’t advance as the engine turns faster. Even car distributors did this. As a result, the timing on a magneto is a bit of a compromise. It’s set so provide adequate spark across the RPM range of the engine.

Electronic ignitions require power to generate the spark.  But they can create multiple sparks when they fire which burns the fuel even more completely.  And they will advance the timing as the engine turn faster.



At the time I started building, electronic ignitions were complicated affairs with multiple boxes and wires and required external power.  I didn’t like that so I was going to go with standard magnetos.  Then I heard about G3i.  This was a really interesting concept.  It used an external box and controlled the spark.  But it used the existing magneto.  Which means, if the box lost power or failed outright, then the magneto would continue operating in legacy mode. The only problem was it was only available in a 12v version. So I made provisions for one in my electrical system design, but waited to see if they would come out with a 24v version.

At the 2016 Sun-N-Fun I stopped at the E-Mag booth.  They had an electronic ignition which was literally a drop in replacement for the magneto. No external boxes!  And… It did not require external power.  It had an integrated generator.  Well sign me up! The owner of the company said that they were currently working on certification. I said I have an experimental aircraft. He said that he could get me one real soon and would appreciate feedback.  I said “no problem”. He said that should be able to get one of his “Non-certified” units in a couple of months.  “Great” I thought.

About a month later, I sent him an email and was told they are focusing on getting certification.  I said I didn’t need a certified unit and he said that they didn’t have anymore non-certified units but that I’m on the list and it should be just another month.  Over the next two years, I would check in and be told “couple months”.

To date, they still aren’t shipping a unit for a 6-cylinder Continental.

At Oshkosh that same year I stopped by the SureFly booth and talked to the owner, Jason Hutchison.  Basically the only difference between his ignition and E-Mag was that he didn’t have a generator integrated in his.  It required a 10amp circuit.  Okay, I can live with that. And it was about the same price as the E-Mag. But I wouldn’t be able to use my existing wiring harness.  He said they would be shipping in… wait for it… a couple months. He gave me his card with his personal cell phone number on the back.

I told him that whoever called me first would get my business. Over the next 14 months whenever I called he said that he was running behind because of whatever.  But he always told me what was holding him up.  And he was very forthcoming.

In December of this year, I received my SureFly SIM6C.

Then I had to get an ignition harness. I had no idea how much one would cost.  I figured a couple hundred.  Turned out to be closer to six hundred. 🙁

But that was for a complete harness (both magnetos).  So if anyone want a right magneto Slick ignition harness for a Continental 6-cylinder, let me know, it’s yours for $300 with free shipping!

I built the airplane but I purchased the engine. Whenever I do anything serious on the engine, I like to have someone that knows engines to work with.  My old A&P/IA from up in Chicago has semi-retired and now spends his time raising cattle and working on airplanes in Tennessee. I told him what I was planning on doing and asked if he would help and he said “Come on up!”.  And up I went.

Pictures of the Bendix magnetos:

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I flew up on Friday morning and at 8:30am we started pulling the old left mag (technically it’s the right mag because the engine is on backwards).  That’s when we started finding pieces of aluminum sheet.  It took me a minute before the light bulb went off in my noggin’ and I looked at the intake ducts on the upper cowling.  To kept the cylinder head temps even, I built a “diverter” to direct the incoming air down onto the cylinders.

2018-03-03 IMG_20180303_115720 It seems the vibration caused it to crack and come apart. So I removed what was left and then we installed the new electronic mag. When it was time to set the timing, Lynn said “we need to find the correct engine position”.  I said, “no problem, I’ve got it marked on the prop flange.” But the new mag wouldn’t fit in that orientation. So we had to re-clock the gear about 20 degrees so it would fit.

New electronic ignition installed:

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The company that did my fuel system adjustments last spring had it all screwed up. So Lynn broke out his gauges and we set the fuel injection system pressures as well.

Once that was done, he hopped in the co-pilot seat and said “Let’s go!”.  You gotta love an A&P who’s not afraid to ride in a plane he just worked on.  🙂

We took off and started climbing. At about 1,000′ the CHT alarms started going off.  It’s amazing how much that diverter helped. I was having a hell of time keeping a couple of the CHT’s below 410. It was very bumpy so we returned to the airport. Once on the ground he asked if I wanted to go to lunch.  I said that I wasn’t comfortable with the CHT’s and that it was probably best if I took off now just in case I had to return.

So off I went.  I made it about 7 miles when I decided to turn around. I had one cylinder that had gone over 420 degrees! When I landed, Lynn asked what I wanted to do.  I said that I had been flying over two years without the diverter so I knew that I could keep the CHT’s under 400 (barely) without it. So that’s not the problem.  My fuel pressures and flow had been too low before he adjusted them, so that’s not it.  Which means it has to be this electronic ignition. So I said that we’re going to have to put the old mag back in.  He agreed.

So off comes the cowling.  I get started on disconnecting the ignition harness while he starts removing the mag.  He mentions that we’re going to have set the timing on the old mag.  I once again say that shouldn’t be a problem since I’ve already got the mark on the prop flange. He comes to a dead stop…  “What?” I ask.

He said “I thought you said that mark was for the new mag?”  I said “Yeah. It’s for setting the timing of the mag.” And then I get “the look”. You know the look.  When you think you know what you’re talking about but you really don’t?  THAT look.

He said “Don, the timing of you Bendix mags is at 22 degree BTC. You told me this new mag is supposed to be timed at top dead center.”  He continued:  “That would explain why the CHT’s were so high. And why we had to reclock the timing gear 20 degrees.”

To say I felt like a idiot would be an understatement.  But that right there is why I like to have someone who knows what they’re doing when I do engine work.

We re-clocked the mag gear, re-installed and re-timed the new mag.  Started up the engine and it ran fine (but it ran okay before so that’s not conclusive). Put the cowlings back on, loaded up and took off again.

This time the CHT’s for the hottest cylinders only sneaked over 410 and I easily got them back down under 400.

On the trip home at 7,500′ (500′ lower than the trip up) with the same OAT, I was indicating about the exact same airspeed (I was hoping for a little improvement) but my fuel burn was .5 GPH lower. I’ve only made one other trip so I’m still gathering data on performance.  After a couple more trips I should be to determine what improvements to expect.

One thing I’m surprised at is the mag check. On other airplanes I’ve flown with electronic ignition, when you do the mag check, the difference between the legacy mag and the electronic mag is HUGE.  The reason (as explained to me) is that when you shut off the legacy mag, you barely notice it because the electronic mag is generating so much spark that you don’t really notice the loss of the legacy mag.  But when you shut off the electronic mag, the old mag is the only thing generating the spark so the engine feels very rough.  I don’t see that with this mag.

When I got back home, I thought about how to make a diverter that wouldn’t crack again. I still have some titanium left over so I decided to try that.  It took a quite a bit of work to get the roll in the back but eventually made it. Hopefully, this one will last a little bit longer.

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