Welcome to my Robin Blog.

It was suggested to me that I start a Blog on my ultralight project the "Robin". I have been working on this project for 4 years. On one of my first days at Vought aircraft, a stress man and future friend named Kenny Andersen walked up to me and said, "Aren't you the Mark Calder that designed the Wren Ultralight" Why yes I am I said. "well what have you done lately?" That was the genesis of the Robin design. The first 2.5 have been spent in the design phase. Actual construction started 1.5 years ago and has actually progressed smoothly. There have been a number of changes from the onset, but for the most part it is following my original concept. I will eventually sell plans for the Robin and make available all molded parts, fittings and welded assemblies. The Robin is designed to FAA part 103 and as such requires no pilots license to fly, although I think its a good idea to actually learn how to fly!! The actual name "Robin" was my Daughter Jamie's idea, I asked her to name the design based on my "cute little bird" theme (Wren)



Every good aircraft design has a "Mission" in mind before the actual design is started. A good designer will refer back to this mission every time a design decision must be made. Good design after all is just a series of good design decisions. On my first Ultralight design the Wren, the mission was to design a high performance low powered aircraft. The reduction of drag was the prime concern. I had been flying powered Hang gliders prior to this and because of this experience, I placed a high priority on climb performance. While most designers chose bigger engines, I chose lower drag and high aspect ratio (low span loading) wings. The Wren could out climb conventional Ultralight with up to 65 hp. The Robin follows this philosophy, but tries to improve on the performance of the Wren. Ultralight are not built by "rich" people, they offer an inexpensive means to enjoy one of the greatest experiences of my life, low speed soaring and flying.



Design Concept



The cost of an aircraft is directly proportional to its weight. , if low drag can be achieved then lighter and cheaper engines can be used. The Robin expands on the design mission of the Wren by using a longer span (40') wing and using a low speed laminar flow airfoil, (Wortmann FX 170) The leading edge of the wing on the prototype is molded fiber glass. The spar has been placed at 33% of the wing chord because the chosen airfoil is laminar over the first 32%. The aft covering is light weight Dacron Fabric. The leading edge of this fabric is purposely pinked and placed at the 32% chord point to facilitate laminar transition and elimination of separation bubbles. The main difference between the original design of the Robin and the current final design is the elimination of the single mono wheel retractable landing gear. Part 103 does not allow for a retractable landing gear. Which is really unfortunate because I spent a long time designing a really neat mechanism!!

In the course of the 4 years I have worked on the Robin, the structural design concept has evolved radically. Originally I was going to draw on the design of the Wren and use essential the same construction concepts. The original design of the Wren was heavily influenced by my Friend Steve Wood's Sky Pup design. I lived in Wichita Kansas and worked at Cessna Aircraft along with Steve. I watched his progress on the Pup and was very impressed with his concepts. I adapted the concept of using Styrofoam sheeting as the shear panels for the fuselage and the wing ribs. I did not however use the foam for the shear webs of the wing as Steve did. I originally wanted to build the fuselage of the Robin in a similar manner. Weight and the desire to not use foam for the basic structure due to the danger of fuel leaking eventually drove me to a all wood fuselage design. The wings were designed to take advantage of the Graphlite carbon pultruded material pioneered for the experimental aircraft by Jim Marske. I was familiar with this product from my experience at Bell Helicopter where it was considered in the construction of the V-22 wing.









Wren Ultralight

This is the Story of the Wren, I think this would make a great Daytime Soap opera, I would call it:

"As the Wren Flies"

Here are some old pictures of my old Ultralight design the "Wren" and me at a much lower gross weight!!!


 The Handsome devil and his ultralight

I was an avid hang glider pilot and and Powered Hang Glider pilot before I designed the Wren. One year at the 1979 Oshkosh Airshow, I was at a small airport outside of the airshow in New Berlin Wisconsin testing one of the early powered Trikes. I had an engine failure on climb out and hit some power lines trying to land. I didn't see the lines because they were obscured by a tree line. I had a perfect unpowered approach with plenty of clearance over the trees when I dropped the trike into something similar to a slip to kill as much altitude as possible. In doing so, I flew right into a high voltage feeder line for all of Neenah County. Those poor people lost their power for a half day and I lost all feeling from my neck down.

 I broke my back in 5 places. 3 broken vertebra joints and 2 compressed discs. I was paralyzed from the neck down. I was fortunate to have been sent to the Neenah Medical center in Oshkosh where the attending physician was a Mayo Clinic teaching professor on spinal injuries. I credit this doctor for me being able to walk and run today with no pain. He told me emphatically that if I wanted to walk out of the hospital I had it within my self to do it. Later he gave me the best medical advice I have ever had. "Do not let anyone ever cut you!!" He told me that future doctors would see me as their meal ticket and means to buy their cottage or second house, boy was he ever correct!!

I spent 3 months in the hospital, after the third day I started to get feeling back in my limbs and most embarrassingly during a bed bath by my nurse!!! I was still on heavy pain medication when I first tried to walk, I took one step before I passed out. Within a few days I was able to wean off the pain medications. By this time the Oshkosh airshow was over and  I received a visit from Paul Poberezeny, the then president of the EAA. He wondered if he could get me anything and I asked for some EAA design manuals and a small drafting board (he loaned me his) This is how the design of the Wren was started.


plan view drawing of the Wren
 In the remaining two month at the Neenah Medical center I pieced together the design of the Wren. Because of my recent experience, I placed a high priority on climb rate and crash safety.
I was discharged from the Hospital in late October.  I would like to thank my Friend Steve Wood (Sky Pup Designer). In my absence he moved me from my old apartment and rented me a storage locker for all of my things. Steve was there when i needed help and I appreciated it very much.
I was pretty much broke at this point in my life. Not having worked for 3 months  I was getting anxious to get back to work for Cessna Aircraft. Before I could go back to work, I had to be cleared by a local physician. I wont mention his name, but this is what he told me. " You will have to agree to see me every month for a year, and after that time I'm afraid I will have to recommend surgery".  I had no back pain, and no limit in my range of motion. My old doctors prediction had come true!!!  I agreed so I would be re-admitted and dutifully made 12 appointments, all of which I ignored!!

I went back to work at Cessna and I immediately realized something was just not right. No one was glad to see me back and my immediate supervisor would not look me in the eye. 5 days later I was fired from Cessna Aircraft "for Cause". When I applied for unemployment, I met a former Cessna HR guy  in the waiting room. When he heard my name called he stood up and said I was the reason HE got fired. He was told to backdate my personnel file so they could build a case to fire me. He said this was illegal and morally unethical, and because of that they fired him. Because I was fired "for Cause" I was initially denied unemployment benefits. When I disputed this, using my new HR "friend" as a witness, Cessna failed to show up at the hearing and unemployment was granted. This is what happens in "right to work" states where the rights of the individual employee are subordinated to the rights of a company. This is the reason Unions have a real place in my opinion. You have no individual rights until you are able to collectively bargain.  As far as I am concerned Cessna aircraft can go screw themselves and if you decide to buy one of their new Chinese pieces of crap (C-162 Skycatcher) you get what you deserve. I would not reccomend that any engineer go to work for Cessna.
Getting fired from Cessna turned out to be the best thing that ever happened to me. Believe it or not,  unemployment was  $162/week and not only could I live on that, but I could actually start building an airplane. The first thing I did was look for a cheap place to live and work. I found a small lean to work shop and office at Maize Airport NW of Wichita. I was able to rent the shop with utilities for $150/month. I converted the office into a one bedroom apartment and  started building the Wren.

Graphite roll over cage and Kevlar Crash Tub
 I was fortunate to know quite a few really good and knowledgeable people in the Wichita area, one was the late John Kaufman , Cessna test engineer and glider pilot. The other was my great friend and mentor Neal Lafrance (Culver STF, Tailwind and V-Witt racer). John helped me with all of my stress analysis and design review. I sat at the feet of a real master. I listened to Johns every word.  I can't tell you how much I appreciated John for all of his help. John was always my reality check and kept me honest in my design. Neal on the other hand, was my daily inspiration, he would cheer me up and keep me going. He also conveniently invited me to diner at his house when ever he and his late wife Wanda thought I was looking a bit thin. I love Neal and his late wife Wanda, they were my surrogate parents!!  I was literally living on cases of pork and beans and any rabbits I could shoot out in the field behind the airport. I can tell you from first hand experience, that the only thing worth eating on a rabbit are the back straps, and only when smoked and with barb-b-que sauce!!

The original plan was to power the Wren with an 18 HP Onan engine, this proved impractical. The first flight was attempted by Earl Long of Westport Airport and president of the local Wichita Chapter of the CAF. Earl was not able to break out of ground effect. I was pretty disappointed  and dejected when fortune smiled on me in the form of another  great man named Howard Dearmore. Howard used to own the Maize airport and was an oil and gas developer. Howard maintained a P-210 at the airport and actually continued to do all of the maintenance because the present owners just didn't care. On the day after the failed first flight I was sitting out side feeling sorry for my self and he asked why I was so down. I told him I needed a more powerful 2 stroke and I didn't have the money. He asked how much something like that would cost and I said I happened to know where a good used 22 hp Xenoah  was available for $900. The next day he came by with a new wind sock and asked if I could put it up for him. Sure I exclaimed. Later when I opened the package an envelope fell out with a note and a check for $2000.

It said "Dear Mark, I always drop by the airport to keep track of your progress, it makes my day to watch you. We can't let something like a little money stop this project, you can pay me back when you can"


With that money I bought the engine, a steak dinner, a new pair of boots, jeans  and paid attorney fees to incorporate. Quite a few local people had expressed an interest in investing in my company. I refused all investments until the plane actually flew. After first flight and incorporation, I raised over $200,000 dollars and Wren Aviation was born!!!


Front page of the Wren Brochure


The Wren was designed from the onset to be a safe and crash survivable aircraft. The primary structure was a rectangular graphite section that functioned as a roll over cage. All of the main loads were placed into the 4 corners of this section. The wing carry thru, the lift struts and the landing gear were all tied into this section. The front had a 4 lb Kevlar "crash tub" bonded to it. I borrowed on my experience working at Ford Motor in the safety Crash lab for this design. The rest of the plane used the structural concepts developed by Steve Wood for his Sky Pup. The performance of the Wren was spectacular when compared to other more "conventional" ultralights. I could out climb all other ultralights with over twice the power.
One year at the 1981 Oshkosh air show I showed up with a beautiful kit built Wren built by Jerry Hastings and his father in Cleburne Texas.
Jerry Hastings Wren. This picture was on the Front Cover Of Popular Mechanics

I actually helped Jerry and his father build this plane, but that story is left for the end of this narrative. When we showed up at the air show, the guys from Edmonton Alberta who built the Chinook Ultralight were boasting to anyone who would listen that they "were going to beat the Bloody Wren " At the time there were two parallel flight lines due to the wide popularity of ultralights, on my first flight, I watched the Canadians in the Chinook jump out of the line parallel to mine. They sat on the side line until I was next in line to take off. They then pulled one of the rudest maneuvers I  have ever seen, they sent their ground crew out and held back the next ultralight in their line and pulled in theirs next to me. These guys had a 65 hp water cooled Rotax vs. my 27 HP Rotax and a 110 lb pilot vs. me @ 185 lbs. They also had a 1 Quart wing tank that a ground crewman would inject with fuel just before they took off. They actually tape sealed the pilot into their cabin. When we both took off, they beat me not only on rate of climb, but climb angle. They were literally hanging on the prop and their high drag dramatically increased their angle of climb. After that days flying they crowed to anyone who would listen, that  they had indeed beaten the pants off the Wren. I'm actually pretty proud that they would have considered me such a formidable opponent, but  that really frosted my butt. The Wren had two  2" diameter lift struts that were purposely left unfaired do meet the FAA part 103 speed requirement. By measurement there was a rapid drag rise above 45 mph due to vortex shedding off these lift struts. They accounted for 25 lbs of drag at 45 MPH, twice that at 63 MPH. I went out into Oshkosh after the airshow  and found an aluminum siding store that was just about to close. I bought two pieces of 8 foot 12" wide flashing and had the shop break a "vee" into the middle of each sheet. That night I taped the fairings to the lift strut with "500 MPH" aluminum tape. this is actually the optimum shape, the trailing edge being 3 x th diameter. The next day, the Chinook guys repeated the same rude line cut and pulled up next to me for another rate of climb contest. I couldn't help notice all of the old timers who came to watch, a bunch of them had noticed my new fairings and were giving me the high sign.
Not only did I beat them on rate of climb, but I embarrassed them.They quickly shut down claiming some "problem" and never showed up again at the flight line when I was there. They did however seek out the FAA Representative at the airshow and complain that I was breaking the law with faired lift struts. The FAA to their credit and in keeping with the official policy of not getting involved told them to go back to Canada and worry about it. That was great fun, and I do not mean to demean the Chinook and the good people who designed and built her. I took this all in a good competitive spirit.


Wren Kit Built by John Doerfler
Picture was used in 1984 edition of Janes all the worlds aircraft

Earlier in that year Jim Lawrence the editor of Ultralight Magazine came to see me. Jim was a former actor who played TJ the sniper in the old TV show SWAT. Anyway, Jim took the following pictures for the magazine article. It was great fun shooting these photos. We set up on a bend in the Arkansas river. I was operating off of a sand bank on the river. I was demonstrating takeoffs  in about 3 lengths of the fuselage.


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Me flying the second Prototype
  

From the Ultralight Magazine article.
 The final chapter of the Wren starts with the ABC news program  20/20  This outstanding piece of yellow journalism was called "Ultralights Flying or Dying" This hatchet job scared the hell out of 20 of my customers who had kits on order. Each kit had a non refundable deposit of $1500. Each of these customers canceled within 3 days.
This killed me. If you  have ever run a manufacturing business you will realize how much money this takes and how much money you always have in "float". At the time of the order cancellations I owed over $80,000 to local suppliers. We had laid off every one in the shop.Cancelled supply orders and shut down all of the equipment. My shop manager Ed Mattivi and myself were sitting around getting ready to call the lawyer to stop business and declare bankruptcy. This was extremely painful to me, considering I came to know all of the good people who were my suppliers. I worked long and hard building their trust. I was plowing through the disaster left by Jim Bede when his business failed and most of these people were left holding the bag. Ed and I were just about ready to call it quits when a guy drove up in an old restored Chrysler New Yorker. I will not name this guy, but he claimed to be representing a group of investors in Kansas City who were interested in getting into the Ultralight aircraft business. He asked me if I would be interested in selling??
This was as it later turned out, too good to be true. I figured what did I have to lose?
Well I'll tell you! My good name and credit, that's what I had a chance to lose, although  I didn't realize it at the time. The best example of what happened from this point was an  episode I once watched of the Sopranos called "The Scatino bust out" David Scatino was a "degenerate gambler" that Tony had hooked in one of his card games. Scatino owed Tony so much money that he was forced to take Tony in as a partner in his sporting goods store. . What happened to Scatino also happen to Wren Aviation.
 I actually sold Wren Aviation to this investor in Kansas City for $265,000. At this point I made a huge mistake and went against the advice of my attorney. I agreed to take $90,000 up front in cash and the rest on a note. The phrase  "money talks and bullshit walks" is very appropriate at this time. I wanted the cash up front to pay all of my creditors and have a little walking around money for myself and Ed. The day after the sale was complete, the new surrogate owner , locked the doors on me. He was selling my inventory to other manufactures for penny's on the dollar , a "going out of business sale". He was buying material from any supplier that would extend credit and turning it literally for a dime on the dollar. Like Tony Soprano said, "screw it, its all profit!!"
 I would like to mention that at this point, I did do something smart and listen to my attorney. Just prior to the sale I complied with the "Bulk Sales Act" and sent a letter to every creditor informing them of the sale and telling them I was no longer responsible after the sale date. this one act kept me from being sued later.
At this time I was broke again and had no immediate plans so I went to Cleburne Texas and stayed with my old customer Jerry Hastings. Jerry was gracious enough to put me up in his guest room and together he and his father and myself  built the "Blue Wren " that made it to the front cover of Popular Mechanics. Jerry started teaching me the oil and gas business and for a while I was considering going into that area. When I explained to Jerry what had happened, he started laughing his ass off. He told me that he thought all the sharks were in the oil and gas business. He explained to me that I was actually in the drivers seat on this deal. He said that eventually the money guy in Kansas City was going to realize he was being raked over the coals and was being left holding the bag for the disaster in Wichita. He was right!!

A few weeks later this guy tracked me down in Texas. Jerry took his call and informed him that I was much too busy to talk to him because I was doing oil and gas deals and that my time was very valuable (what a crock!!! but I got a kick out it.) Jerry was such a great salesman, that he convinced Mr KC money to wire 5 grand to Cleburne for my time and gas for his C-210 so we could come up and discuss my future. He even sold this guy 3 slots on a new drilling program!!!  Jerry explained to me that I was fishing for a 2000 lb Blue fin tuna with 20 lb test line. He told me there was only one way to land this fish and that was to give him line!!!! Jerry knew that this guy needed to recoup his losses and that putting the company back together for eventual sale was the only possibility. A new agreement was reached and at this point I made my second mistake and ignored the advice of my attorney. As it was, I had a solid contract that obligated this guy to pay me and my investors $155,000. My attorney informed me that this guy had enough assets that recovery was certain. But I was so in love with my Wren that I agreed to tear up the original agreement and sign a new one. There was one clause that initially I thought was one hell of a good deal, An employment agreement, that obligated me for 5 years to help put the business back on its feet. All agreements were null and void if I left for any reason before this 5 year term. I looked on it as guaranteed employment at a really good rate. Mr Money Bags saw it as his chance to eliminate his $155,000 debt!!

The day after we signed the contract, he hired a moving company to gather up all of the equipment and inventory not sold off from the old Wren Building in Wichita. He moved everything to Kansas City into a building he owned. This was a small business incubator that included a really nice 3 bed room apartment. I shared this with my new shop foreman Rod Pitt. Rod was a mutual friend of myself and Jerry Hastings. The day after we moved in, I met my new Shop supervisor, a guy who currently worked for money bags. Turned out, he ran a garbage truck crew. His instructions were to piss me off so I would leave. At the first meeting this guy shook my hand so hard I thought he was going to break it. At this time I was about 190 lbs and this guy was pushing 280 lbs. I figured most of him was flab, but he sure did hurt my hand.
The next day as I was taking inventory under a stock rack, the door flew open and this guy came storming in. He started yelling at me and called me a "Piece of Sh%t" . He pushed me into the stock rack and every thing came down on my head. I was livid. I jumped out of the pile and pushed him against the roll up door. He in turn grabbed a huge master padlock and took a swing at my head. My boxing experience as a kid kicked in  and I ducked to avoid him but he caught the top of my scalp and open up a long gash. I stated bleeding so bad I could only see red. I bobbed and ducked and then tagged him with three punches, two lefts and a hard right to his jaw. I dropped this guy like a ton of bricks. The next thing I remember I was kneeling on his chest pounding away at his face. I shattered his jaw, broke his nose bridge and cheek bones. Rod Pitt, grabbed me and shoved me off of this guy. He looked me in the eye and said "Mark, stop, you have killed him....". Two of the other shop guys dragged me away and threw me fully clothed into a shower, where I started to calm down.  Rod, drawing on his marine Corp training as a navy Corpsman, made an incision in this guy trachea and gave him mouth to mouth. He pulled the broken nose bridge out of his skull and relieved the pressure. He gave him CPR and saved his life.

About this time Mr Moneybags showed up. He was fully expecting to see me being carted off in the ambulance. There were 12 witness by the way, and everyone made a statement to the police that I acted in self defense. The police asked me if I wanted to press charges. "Hell yes"  I said.

Moneybags was incensed, his plan was a failure. He walked up to me and yelled "Meet me at the restaurant" . I was so upset that was afraid I would turn on this guy next. It finally dawned on me what his plan was. I was ready to pound the crap out of this old bastard!! I decided to walk to the restaurant to calm down. . It was about 15 minutes away, and this guy also owned it. He was sitting there in "his" booth when I walked in. He looked me square in the eye and snarled "How bad to you want this" I looked him back square in the eye and growled "Not bad enough to suck your dick!!!" I thought I was going to stroke the old prick out!! the blood vessels in his nose started pulsating. His face turned beet red and he stood up on the seat and yelled at the top of his lungs "I've kissed many a fine mans ass in my business career" I stood up and screamed even louder "but did you ever suck their dick"

The ole boy got up and bolted from the place. In the 15 minutes it took me to walk back to my apartment, he had changed all of the locks. I was screwed!!! At this point in my life all I had to my name was 30 bucks, a POS 1974 Mercury Monarch , a telegram in my back pocket with a job offer from Bell Helicopter and Mr money bags Visa Card. The first thing I did was call Bell Helicopter HR and see if the job was still available. (Preliminary design designer) They were wondering why they hadn't heard from me in the 3 weeks since they sent it. I explained that I was overseas and had just gotten back. They checked and said Yes, the group was still interested. I asked if I could start tomorrow., they said how about Monday? I then called Jerry and asked if my old room was available. True to his Texas hospitality, it was. The next stop was K Marts, and just like the Rain man said, "K-Mart Sucks" . I proceeded to run the Visa card. I bought underwear and clothes for 14 days. I bought 5, 5 gallon  gas cans and then went to the deli and bought 6 submarine sandwiches. At the gas station I filled the gas cans and the tank. Off to Texas I went!!!

Somewhere around Emporia Kansas I tried to top off the fuel tank and they kept the Visa card. The rest is history and that is

 "As the Wren Flies"


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