Electric Xenos-B Electric Quick Build

[taildragger]

Pete, What percent complete are you?

[Scott Todd]

That's an easy answer. 95% done. 95% to go.

But we would like to see some photos. We ALWAYS like photos :) I couldn't figure if they were available in the EAA log.

Scott

[drPete]

>...percentage?

Difficult to say, but like Scott says, it is an easy question to answer.

Previous link to the EAA's build site was directed to the reports, better is the home page here for photos https://eaabuilderslog.org/?blproject&proj=7ZEd3Y0x4. Also used MyKitlog http://www.mykitlog.com/drPete for a while, but it is long in the tooth and tied to a Windows app. Moved much of the old log to the new, minus pix.

It is a bit worrisome to me that the FAA's latest REVISED LISTING OF AMATEUR-BUILT AIRCRAFT KITS Updated on June 22, 2021 https://www.faa.gov/aircraft/gen_av/ultralights/amateur_built/kits/media/amateur_built_kit_listing.pdf still has no evaluation of the Xenos B Quick Build kit for the 49% rule. My worry is that the application for repairman's certificate, in my understanding, is at the time of the airworthiness inspection. However I really have no experiential knowledge regarding the process.

The electric motor looks to be a fantastic innovation, particularly for this aircraft and its mission of pure flying fun. I am increasingly jealous of your choice of power plant.

[Scott Todd]

Download the checklist from the FAA and start on it. You shouldn't have any problem getting enough boxes to meet 51%. The FAA pre-approved list just lets people skip this step.

[wlarson861]

Dr. Pete
you can get a repairman's certificate any time. They must be issued by the fisdo. My airworthiness Certificate was issued by a DAR in October, I went to the fisdo the following September for my certificate. The first annual was done under the temporary card.

[drPete]

Thanks for correcting my misconceptions about obtaining a repairman's certificate. One less thing to worry about.

Pete

[racaldwell]

Yes, 4500+hrs is correct. But my Xenos is not your typical Sonex. For example, I wanted to learn and gain experience in more than the ordinary composite construction so I decided to learn vacuum infusion to make lightweight wingtips. That took six months to make molds of the kit wingtips and perfect the vacuum infusion technique. The result is a wingtip I can pick up with one hand. And I have embedded aluminum to give the rivets that are used to attach the hinges something more than just fiberglass to bite into.

There are thousands of AN426 & AN470 rivets used, all exterior are AN426 where I can get a bucking bar on it. All interior are AN470. Every piece of aluminum was alumiprepped and alodined before riveting. The cockpit interior and the completed exterior was epoxy primed. I live right next to the ocean so corrosion protection is important.

My swingback canopy has a composite skirt that nests onto the turtledeck, just like I made for my RV6. I also have composite gear leg intersection fairings and empenage fairing. My cowling was a vertical split that I made into a 3 piece cowling. I made inlet lips that are separate pieces and help fasten the upper & lower cowling together. The inlets have more rounded edges than stock. The inlets fit into a composite cooling plenum that fits over my CAMIT 3300 of the same design as I did on my Lycoming in the RV. The oil cooler air is ducted in a composite plenum from the opening below the prop, again with rounded edges and this plenum also supplies air to the Jabiru air filter/carb heat box. The air is delivered via smooth composite ducting I made (using a bicycle inner tube as the bladder.)

I made an adjustable cowl flap that includes retracting front angled lips on the openings. My instrument panel is my own design that is two inches more than stock. It has a structural channel along the bottom that is attached to the longerons and the channel is a trough for wiring behind the panel.

I used RV nosewheel pants for the mains. I made mounting brackets based on the Van's design and incorporated a self aligning socket inside the wheelpant for the outer axle piece to fit into so there is no guessing on lining up the bolt hole.

I made a baggage compartment with 0.025 bottom and 0.016 side skins. This is riveted to ribs on the bottom skin again similar to the RV design. The bay behind the baggage area is a hat shelf with the rear closed off. So if I want to carry my guitar somewhere, I can. I wanted the rear fuselage sealed as much as I could to curtail airflow into the cockpit from the tail area.

There's more like the foiled transponder antenna I made using a foil section I designed back in my windsurfing days. Anyway, you can get the idea I went into the Xenos project because I like to build and learn and come up with some original designs without deviating greatly from the Sonex design. I built the motorglider I wanted. I had the Blanik L23 construction in mind.

But the real reason it took 4500+ hours is that I am slow as in not in a hurry. I take the time to round every corner and smooth every edge no matter how mundane the part is. My RV6 took 4000 hrs but it had probably 1/3 the parts count as the Xenos. It is interesting that the cost for both came out to be $50-55K, both with new engines, prop, etc. But the RV was in '90's dollars.

And now it is done. Just a couple of trim stripes to paint tomorrow and then next week ground handling tests then 1st flight.

Rick Caldwell
Xenos 0057

[taildragger]

Wow racallwell, you are a master craftsman! Thanks for taking the time out of your busy schedule to post this detailed description. This is my first full kit aircraft build. My prior experience was with an all-wood Fisher FP-202 Koala, where I totally refurbished it, including full fabric re-covering, overhauled the engine myself and re-gluing all wooden joints. I am also a man who has “calculated impatience”, so I have a few questions:

1) I have not read the plans but believe the Xenos mostly uses pulled non-flush rivets. The most efficient airspeed to fly a eXenos is 60MPH. What would the efficiency difference be at 60MPH between using flush rivets vs the non-flush pulled rivets? The same question for 80MPH and 100MPH.

2) Do I need to prime every piece of structural piece of aluminum? I live less than 100 miles from the ocean so am technically in a high-corrosion zone.

My instrument panel will mostly look like a Tesla: big 12.9 inch iPad screen; very minimal with a 3ft horizontal plenum ventilation bar.

[Scott Todd]

I'll throw in my two cents as an Instructor, builder of three flying airplanes, test pilot of 13 new airplanes, and retired Aerospace Engineer.

At 60 mph, those rivets sticking up may cause enough drag for a knot or two. There are basically two parts to drag. Parasitic and Induced. Parasitic is the antennas, rivets, handles, etc. Induced drag is that caused mostly from the generation of lift. The induced drag is WAY higher than those rivets that mostly live in a boundary layer. Sonex uses flush pulled rivets on the wing leading edge to appease some critics that think this part of the boundary layer may contribute to more drag.

As the speed goes up, the rivet heads will contribute more drag. How much is pretty hard to say without a ton of math or computer simulation. But since the Xenos is a motor glider designed to operate around 60, it doesn't matter.

Cessna's and Pipers are NOT primed on the inside. Go to the airport and look inside some of them that have been on the ramp for more than 50 years. Some get corrosion, some don't. Are they taken care of? Do they collect standing water inside? Are they taken care of? I know I said that already. A well loved airplane with regular cleaning, good annuals, and covers, can last a lifetime outside. Your Xenos, most likely hangared, will most likely last longer than you.

Weight is everything. Save it every place you can.

[racaldwell]

I say build the plane that you want, the way you want. My vision of a sailplane is to take effort to reduce drag where possible. So for me looking at a sailplane with domed rivet heads all over the exterior just is not going to work for me. Even if it is only 1 point penalty on L/D. That is just not the plane I want. So mine is flush riveted, mostly AN426 on the top surface of the wing. You can pay Sonex more for the flush rivet option like I did. But I ended up selling most of those (& still have some more for sale.) I'll post a picture of the wing.

I worked as an A&P in St. Croix USVI before I went into engineering. I spent much effort there fighting corrosion on a lot of airplanes. Antilles Airboats was the extreme. I have seen 172's on the rental line here on the Space Coast of FL that I would not fly because of corrosion. My RV6 was alodined & epoxy primed and hangared its entire life. It is 21 yrs old now and it has exterior filiform corrosion that I cannot defer any more. I'll be stripping it and repainting this winter. I have some Sonex parts from my kit that I did not use that are in my hangar and there is corrosion on them. They are just sitting there, exposed to the air in the back of my hangar 4 or 5 yrs. I can't say alodining & epoxy priming every part before riveting is the best corrosion protection but it is good enough for some large aerospace companies. And it is not a guarantee as my RV shows. But the interior of my RV looks like the day I built it. And I know of other RV's here that also has exterior filiform corrosion. One friend had his RV stripped and repainted and now some yrs later, it is coming back. His is also hangared here at KMLB. I know others say Corrosion-X spraying works for them. But for the time & money to complete a large project like building a Xenos, I would not dismiss the corrosion that will happen in a coastal environment.

Rick Caldwell
Xenos 0057 N137RC