[Cozy MKIV Information]
COZY NEWSLETTER #37
Table Of Contents
Brock Mfg. should now have all of the Cozv Mark IV parts in stock and on the shelf. It took longer than expected to complete the first lot of 60 nose gear forks, but we were told the machining is now complete, and they are in assembly as this is being written.
Nevertheless, we have made good progress. We are grateful to Cozy builder Doug Hoffman, who came down from Minn., stayed with us for a week and helped, and Cozy builder Gene Davis, who comes down from Globe once a week to help. Since the last newsletter, we received the pre-fab turtleback (we had made our own, shipped it to Feather Lite who used it to make a mold, and then shipped us one that they made) and strake kit that Feather Lite wanted us to use, critique, and approve. The new canopy bubble from Airplane Plastics fit the turtleback well, so we mated the two together, and built the canopy frame. We found that the side windows from the 3 place did not fit well in the Mark IV turtleback. so we made molds and sent them to Airplane Plastics to make special, larger windows for the 4-place.
After completing the canopy, we decided to paint the inside of the fuselage while we could still turn it on its side, and then we mounted the centersection spar and bolted both wings on in preparation for building the strakes. Visitors are impressed when they see the airplane with wings attached sitting inside a 2 car garage, with one wing going through the double doors into my shop, which is alongside the garage. Invariably thev ask how we are going to get it out.
The Feather Lite strake kit consisted of two straight, 8 ft. long, airfoil shaped leading edges, ribs and baffles. The builders supply the top and bottom skins, which are essentiallv flat pieces. We were very pleased that we were able to build two perfectly straight strakes, which joined the wings and centerspar exactly, without requiring much, if any, contour filling. This didn't happen automatically, however. It was the result of carefully checking alignment in every step of construction. We found that the rib shape and baffle dimensions shown in the plans only approximately correct, and that the ribs and baffles had to be trimmed in assembly, using a long straight-edge, for a correct fit.
With strakes complete, we had to make and fit cowlings before removing the wings. This meant installing the engine, and before we could do that, we had to have an engine mount made. Mike Youngblood, who builds the engine mounts at Brock Mfg. said he would give us 2-day service if we faxed him drawings, so we got busy, made up drawings, faxed them on a Thursday morning, and reviewed them with him on the telephone. The following Monday the engine mount arrived!!! The workmanship (welding) was beautiful, and the dimensions were right on the money, so we got a hoist and hoisted our engine out of the box. The mount fit our engine with no interference and ample clearance at the fuel pump and the oil filler neck - the two spots we were concerned might be problems. We called Brock Mfg. and gave our verbal approval.
We hauled our prototype cowling molds back from the hangar, dusted them off, polished them up, and made top and bottom cowlings. We anticipated some problems fitting these cowlings to the plans model, because of minor differences in the firewall shape between the prototype and the plans model, but a good fit was obtained with only minor modifications. We will eventually have to ship our cowlings off to Feather Lite, to use as plugs so they can make permanent molds, but for the present, at least, they are staying on the airplane.
The new 4-pipe exhaust system from Dave Mendenhall just arrived a couple of days ago. We installed it immiediately to see how much we would have to modify the cowlings. Fortunately only the top cowlings needed modification, and not very much at that, so we were pleased.
About the time we were working out the details of this design, Cozy builder Dave Mendenhall asked if he could be considered as a supplier, since he had a lot of experience welding stainless. We turned him loose on the new design. He started out with much enthusiasm, but ran 'into a lot of bad luck along the way and decided he couldn't handle it along with his regular job. In the process, though, he involved a friend who owned a muffler shop, and this friend, Gary Reed, decided that it would be a good fit with his automobile business.
We have the first set of pipes that Dave and Gary made. and are very pleased with them (see pictures). They fit our 4-place well, and we have asked Gary to make a set for the 3-place to check for fit as well.
The new exhaust system uses over $250 worth of matenals, and takes about 16 hours to build. We asked Gary to price them under $500. We think this is pretty reasonable since Hal Hunt has priced his pipes at $450 plus shipping, and his have neither slip joints nor heat muffs.
Dewey sent us the part number on the gas spring (Mighty Lift #95002) and the installation details. Shortly thereafter Vance Atkinson dropped us a note saying he had installed the same spring on his canopy and was very pleased. With such impressive recommendations, we rushed down to our local auto store, bought the same gas spring, installed the hardpoints per Dewey's instructions. and installed the spring. When we started to close the canopy we heard such a loud groaning noise and crunch we stopped in our tracks. It sounded as though bulkhead TB1 was about to pull loose from the turtleback. At this point, we got on the phone to Mighty Lift and asked what force this spring was rated at. They said it was rated at 103 lbs!!! I hauled out our bathroom scale and let the canopy rest on it, and it registered only 16 lbs. Obviously this was a case of overkill!
I tried to find out from Mighty Lift if they had a gas spring of the same dimensions with about a third of the force. When they found out this wasn't an automobile application. they refused to provide any information. After much phoning, I finally was referred to a company called Service Plus Distributors (215) 639-7810. The gentleman I talked to, Stewart, said they engineer industrial applications for gas springs, and would be happy to engineer mine. I said all I needed was a gas spring about 15" long with 30 to 40 lbs. of force. They suggested a SPD-5150-40, for $29. He said the industry standard for ends was sockets, so I would need ball fittings for each end for a nominal additional cost. I asked him to send me a ball stud and a right angle ball bracket.
About the same time, good friend Tom McNeilly suggested that the spring be mounted differently, so it would go over center when the canopy was half open. Then it would hold it open in the open position, and closed in the closed position. Tha wav it would provide an additional degree of safety, should someone neglect to lock the canopy, and the safety latch failed (like happened to Vance). This seemed like a good idea, so I mounted one end of the spring 8.5" up the side of the right headrest. and the other end on the horizontal member of TB1 so it just clears the left headrest. Guess what? It works like a charm. It takes 26 lbs. to lift the canopy from the closed position. Half - way open, the spring takes over and lifts it the rest of the way, and it opens to 64 degrees!!
This is so slick we are going to show it in our Mark IV plans, and we think 3-place builders could do the sam thing with the same spring. First locate one end of the spring on the TB1 cross member as close to the left headrest as possible. Then open the canopy 60 degrees or so and see where on the right head rest to fasten the bracket. The hard point on the cross member was made by routing out some of the 3/8" PVC, and then floxing in a 3/8" thick alum. slug (1/4" would also work). After cure, a 1/4" hole was drilled and tapped to 5/16" x 18 for the ball stud. 4 layers of BID reinforcement locally is optional. On the headrest, we routed out some foam and floxed in a 1/4" thick alum. slug and later drilled and tapped for 10-32 screws to mount the ball bracket.
Original Equipment Lightweight Replacement Starter 17.5 lbs. 8.0 lbs. Alternator 15.5 lbs. 6.0 lbs. Carburetor 5.0 lbs. 3.0 lbs. Total 38.0 lbs. 17.0 lbs.This saving of 21 lbs. in the engine compartment is extremely significant!
Howard Francis 5631 S. Crows Nest Rd. Tempe AZ 85283 (602) 820-0405
When the Cozy is parked nose down and the wings tied down, the nose tie down does not have to be substantial. We have a removeable pitot in the nose, and when we park we remove it an replace it with an eye bolt attached to a 1/8" pipe plug.
We know that more of you have made first flights. Please keep us informed!
If you have a Long EZ and are using the heavy duty brakes, this is what must be done to fix this potential problem. You must install heat shields between the axle mounting flange and the glass/epoxy main gear strut. This shield is purely a radiant heat shield and, as such, must be large enough to prevent the hot brake disc from "seeing" the gear strut. A fan-shaped, 1/8" thick alum. heat shield that extends up above the brake disc bv at least 1/2" works fine. You don't need any more than that. We have seen more gear legs damaged in this way than we care to think about and all of them had exactly the same damage; i.e. the epoxy had been boiled or vaporized out of the glass strut directly opposite the brake disc. The damage was confined to an area the same shape and size as the disc. The damage can, and does, occur even through fiberfrax insulation. I repeat, this damage is caused by radiating heat from the red hot brake disc and is locally confined to a small section of gear leg directly opposite to and the same shape and size as the disc.
To our knowledge, this damage has only ever occurred when tight fitting wheel pants were installed. Apparenty with no wheel pants, the disc gets enough cooling air flowing over it to keep it from getting hot enough to do this kind of damage. So if you have tight fitting wheel pants, expect your brake discs to get very hot and protect the gear with an aluminum shield. In addition to the radiating heat damage, it is possible to generate enough heat inside an unvented wheel pant that this trapped oven-like heat can soften the epoxy and cause the gear strut to bend, usually at the highest point in the wheel pant. To protect against this kind of damage, you must wrap the strut from axle to the top of the inside of the wheel pant with Fiberfrax insulation. held in place with silicone (RTV). We have found wrapping over the Fiberfrax with aluminum tape makes a neat job and helps hold the Fiberfrax firmly in place. This will help the "oven heating" problem (as opposed to red hot radiation), but you must provide a place for this hot air to "chimney" out of the wheel pant. A vent of some kind is needed. This vent should be placed at the highest point in the wheel pant when parked, whether you park 3-point or nose down. This position niav change a little depending on the wheel pant design. The important thing here is that the vent must be high to allow the trapped hot air to flow out and pull cool air in around the fire. These two fixes together will help prevent a softening of the epoxy-type failure.
The NACA scoop-type inlets and outlets we have all seen on wheel pants probably don't have much value because you really need the cooling after you come to a stop. The NACA-type cooling scoops are generally too low to allow good chimney venting when parked.
The single man important thing is not to conduct extensive braking /taxi tests with wheel pants installed. Do all initial taxi tests with no wheel pants. Once the airplane has been flown and signed off, generally you will not find a need to do extensive taxiing/braking. If you do have to check-out a new pilot prior to his first flight in his own EZ, remove your wheel pants before you allow someone to practice for his first flight in your airplane.
If you have to taxi a long way with a strong crosswind, for example, the full length of a 10.000' taxiway on a day with a 90 degree temperature, you will have to ride one brake all the way. Under these circumstances, you might consider removing the affected wheel pant as soon as you park. This small inconvenience is tiny compared to getting stuck in some remote area, miles from home, due to a failed gear leg. And if you are unfortunate enough to fail a main gear leg due to heat, contact Mike Melville at Scaled Composites to borrow his steel splint that was made specifically to ferry a long EZ home with this problem. So far, it has been used on two Long EZs and one Cozy, and it will fit left or right Long EZ main gear legs!
We know that when Bob Beard ditched his Varieze in the water off California, it overturned and he perished. We don't know whether he had lowered the nose gear (or had it up, trying to stretch his glide), and if he had, whether he had the door in front of the wheel as shown in the plans. This might be an argument for following the plans, attaching the door to the wheel rather than installing doors on the bottom of the fuselage, which look nice but probably don't do much for performance.
Editor's note (Ben Owen): This is not the first occurrence where a fiberglass aircraft has had peel ply left in. Peel ply's primary function is to draw the resin up out of the matrix and to keep the resin "green" so that the next layup will adhere. If the peel ply is left in the structure and the structure built up around it - you just have a useless unit. If you are looking at a composite part to buy, sav a wing, and you lift up on the wing tip and vou hear it crinkling inside the wing, someone probably left peel ply in the wing. There is no way to correct this and the part must be discarded at this point. Peel ply will cause ihe structure to seperate piece from piece. If you realize upon inspection of an amateur built aircraft that the builder has left peel ply in the struaure, either the part has to be torn down to the peel ply, the peel ply removed and the part redone, or the part must be discarded. Due to the nature of most fiberglass structures, thls implies that the structure will have to be discarded and it is recommended that it be demstroyed at that point. The above occurrence is not the first time that this has happened, I have had several calls here at EAA Headquarters on this very problem.
The Cozy dinner will be on Friday night, July 31, 6PM at Robbins, like last year. We reserved for 60 people. It will be on a first come, first serve basis. List year we had an overflow crowd and they set up extra tables. See ya there!
The Cozy forum will be Saturday Aug. 1, 1-2:15 PM in tent #3. We wish to encourage builders to participate, so you won't have to listen to us the entire time.
Bolt Dia. Torque 3/8" 200+/- 25 in.lbs. 7/16" 250+/- 25 in.lbs. 1/2" 350+/- 25 in.lbs.Note: The values may vary depending upon the number of laminations. To bring a wooden prop into track, it is permissable to go to the high end of the propellor torque on one side to adjust its track.
Just a note to update you on the flight testing of our Cozy N3EP since you reported our first flight on April 20, 1992 in Cozy Newsletter #34.
The 40 hour test period was completed some time ago and now my wife Pearlie and I are ready for a few tnps.
N3EP weighed in at 990-lbs. The engine is a rebuilt Lyc 0-320 E2A, 150 hp. The propellor is a B&T 62 x 75.
I found the Cozy to be a very fast, high performance airplane. All controls are smooth with elevators and ailerons normal and satisfactory. Durtng several speed runs at 3000' MSL and 2700 RPM, N3EP indicated 160 Kts. The stall turned out be a non-event with no wing rock or tendency to fall off on one wing. It's a delight to fly.
Thanks, Nat, for a very fine airplane.
Ed & Pearlie Moulden
Dear Nat & Shirley,
Some news from France. I'm still enjoying the Cozy. Nearly 500 hours without any problem. It's really a wonderful plane! We moved to Ugnan, a little village near Beziers and we'll expect to move again to Montpellier next summer because of my job.
Happy new year,
As I reported earlier, I have been overhauling the engine of my Cozy for the past 3 months. It is an 0-320 E2D and was purchased as a run-out with 2500 hours TT. I put 170 hours on it since the first flight, and it performed well, but oil consumption was high, and a major was inevitable. The last time I flew, the CHT went to 525 F on climbout, so I throttled way back and nursed it home. I tore it down and found that the #2 exhaust valve was stretched. Otherwise, the engine looked far better than I had expected, considering the TT and the fact that it had never been topped.
I sent the cyls to ECI for Cerichrome remanufacture and fitting of 160 hp pistons. I also sent the crank, cam, lifter bodies, case, etc. for overhaul. They line-bored the case. All other parts were polished and returned yellow tagged to standard tolerances. It took 6 weeks to get everything back. I then took all the moving mass to an automotive shop that builds racing engines and had them dvnamically balance everything to within 1/4 gram. With the help of a friend and Lycoming manuals, we reassembled it over a two week period. A new oil pump, hydraulic lifters, and scads of small parts were also installed. I ended up spending around $5500 for parts, labor and shipping. A ridiculous figure, considering what fthat will buy in the automotive market.
I was fortunate in that my friend Rick Cahill's Cozy was not quite finished, so he loaned me his 62x74 prop to use to break in my engine. I had planned to fly the Cozy to the Dominican Republic as a participant in the Dominican 500 early in Feb, so I needed to get some time on the engine. After about 12 hours, the temps and oil consumption had started to stabilize, so I left on the trip. It was a week long fly in to the D.R. in celebration of the quincentennial of Columbus's discovery of the new world. We flew to Ft. Pierce, FL, and then off across the pond! I had never done any flying over water and do not have either a VOR receiver or an ADF, so I installed a Sony GPS receiver. It was a good thing too, as the Loran could not navigate past Grand Bahama Is. We landed for fuel at Great Euma Is. The next stop was at Providenciales. It was getting dark, so we spent the night and departed early the next morning for Santiago, D.R. It is about 200 nm to the island and when we got there, it was solid IFR. The clouds build around the 10,000' range on the south side and unpredictably will cover the entire country. We diverted to Grand Turk Is. in the Turks and Caicos. about 180 nm north and spent two wonderful days goofing off and snorkling. Grand Turk is a trip back to the 19th century. There is very little to do there, but the beaches are beautiful, the pace is slow, and the people are very friendly. We finally flew into Santiago where we met the rest of the group. We ferried the Cozy to San Isidro AFB where the aircraft were stored, and then spent three days in Santo Domingo. We were treated like royalty. The Dominican people had received much advance warning as to the fly in, and as we moved along on our tour busses, they were lined up along the streets cheering and welcoming us to their beautiful country. There were three other homebuilts on the trip, 2 Defiants, and a Glasair RG. It was a great trip, that would not have been possible for me without the Cozy. It was a hit everywhere we landed. The tower controller at Grand Turk had us do a fly-by so he could get some photos.
The Cozy performed flawlessly on the trip (3200 nm total). There were many times the GPS showed a ground track over 200 Kts. For a while at 11,500' we had a GT of 230 Kts. Not bad for something you built yourself in your garage! I have an Ellison TBI to install, and a Performance Props 3 bladed prop on order. I am anxious to get these things done, as I feel that then my airplane will have developed it's full potential. Thanks again Nat for a wonderful airplane!
I came across a computer bulletin board that you might want to mention in your newsletter. It is run by the FAA to promote the rapid exchange of safety items throughout the small community. There is a bulletin board area to discuss questions or building hints, and a database of service reports to share information on equipment failure, etc. This database is used primarily by homebuilders. I found that browsing through the bulletin board and the service reports to be very enlightening and educational. This bulletin board is open to the public, and any activity on it is anonymous. The number is (800) 426-3814. Even the phone call is free.
I have begun construction on my Cozy Mark IV Serial No. 117, and am halfway through Chapter 4. David Haggard of Wichita was kind enough to give me a ride and let me fly his 1991 Sun & Fun reserve grand champion Long EZ. It was quite inspirational: the Mark IV can only be better.
Your efforts are greatly appreciated. I am about to complete Chapter 6. I'll send pictures when I get to the "garage flyable" stage.
I have a few things to pass on to other builders.
1) I tried four unsuccessful times to bend the fuel valve mounting bracket into the position shown in Fig. 17, Chap.6 without getting cracks. 2024 alununum is strong, but is prone to crack when bent to such a sharp radius. If cracked, this bracket could fail and make it difficult to switch tanks in flight. I would recommend 3/16" radius instead of the 1/16" radius shown.
2) Instead of using wedges to hold the 0.25" longeron strips together as shown in Fig. 2, Chap. 5, wrap strong twine back and forth across the jigs around the ends from one longeron to the other. This "corset" arrangement worked well for me.
3) Don't use weights to hold down the wood pieces LWX and LNW shown in Fig. 14, Chap. 5 or the Clark foam in Fig. 17 if the fuselage side is not supported underneath. The slight sag in each side will cause over a 1/4" gap to occur when you get to Chap. 6 and start assembling the pieces you worked so diligently on in Chap. 4.
4) It would be helpful if builders would share part weights as they progress. I believe my layups are high quality and light, but I would hate to get to the end of the project and find out it's 100 pounds overweight (ugh).
Considering I only work on the Mark IV in the evenings and sporadically on weekends, the project is progressing much faster than I thought it would. Thanks for a great set of plans!
I want to share with you an experience I've had recently that you may wish to pass along to other Cozy builders. On a recent flight in my Cozy N41CZ the engine began running very rough when I reduced the throttle to near idle to practice slow flight. Opening the throttle smoothed out the engine but the RPMs were way down and I could only get about 2300 RPM max. CHT on #2 cylinder was down to only about 100 deg. so it seemed a good bet it wasn't firing. I also noted that the electrical svstem was no longer charging. I headed back to the airport and made a normal landing. I pulled the plugs in #2 and noted they were both covered with oil sludge and that there were several tablespoons of oil in the bottom of the cylinder. This cylinder had been fouling plugs ever since I started flying my Cozy 4 years ago. I've just had an overhaul done. The problem was a badly worn exhaust valve guide which allowed oil to be sucked into the cylinder at low throttle settings. Much to my shock the real lesson here was much more serious than the cylinder!
Remember I mentioned that the electrical system had stopped charging? Well, upon removing the cowling I discovered that the pulley, washer and nut from the Mitsubishi alternator were missing and the belt was chewed up!!! Fortunately, I found the pulley halves and washer in the bottom of the cowling and the nut was found balanced on top of the #3 cylinder!!! All the parts were there and no prop damage. When originally installing, it seemed too difficult to safety this nut so it was a regular item that I checked. I believe the rough running of the engine due to the fouled plugs caused unusual pulses to be transmitted to the alternator which backed off the nut. I have since drilled the nut and shaft in a drill press and added a cotter pin. I was very, very lucky! The large pieces that came off could easily have gone out the back and chewed up my prop or worse! The lesson here is that safety wiring or pinning is essential. Anything that can come off willcome off! Hope to see you at Oshkosh this year!
I trust this finds you and Shirley doing well. If you remember, I visited you along with my wife and children before we moved from Williams AFB last April. You were kind enough to show us your Cozy Mark IV prototype and proof of plans in the works.
Since our visit, I have completed my B-IB Aircraft Commander course and settled into our new home in Rapid City. I enjoy flying the B-IB bomber and, although it's a kick to fly a $230 million dollar aircraft, I'm looking forward to building my Cozy Mark IV from your plans. My wife is as excited, if not more so, as I am to work on this project.
I would like to know if there have been any incidences of unrecoverable stalls with your design as has been experienced in the Velocity design (Editor: None). If there have been none, do you anticipate the possibility of an occurrence of an unrecoverable stall (Editor.- Very improbable if operated within the approved cg. range). Thank you again for your time last April and now.
Ken Baker, C.W.
Just a short note to keep in touch. I am planning to visit Oshkosh for the first time this summer (in a spam can).
I just completed the fuselage sides and attached the longerons. Finally I have a "big" piece to show for all my work. As a dentist who wears latex gloves all day, I find the powder or the latex itself can become irritating, and I agree with you, to skip the gloves. I have been using generous quantities of ply #9 gel and paper towels.
Our local EAA chapter will help one of our members. Charlie Gray, with the Sun & Fun races this year. Conspicuously absent from last year's race were Cozys. If 3 aircraft of one type (Cozy) enter, a separate category will be created. All homebuilts race against the clock, not each other. For more infotmation. contact Charlie Gray (407) 466-4660. Continued good luck with the plans and construction.
S. Blank, D.D.S.
I am getting ready to put the bottom on my Cozy. I haven't made as much progress over the last month due to the arrival of child #3 (BOY #I!) on July 31. and a heavv project schedule at work. I'm the manager of a group developing network software for the largest ATM system in New England. In banking, having a job is the best Christmas present there is, so I'm not complaining!
I'm including some photos taken this summer when we assembled the sides. The main landing gear extrusions were cut on a band saw and hand sanded. Lightening holes were drilled out at a friend's hangar. He's also given me some back seat time in his Long EZ. I'm getting construction help and flying time at the same place! This was my first experience working in metal and I give credit to anybody out there building an entire airplane out of the stuff. Still I hope to push on and get the fuselage glassed in time for a Mall Show one of my chapters puts on each year. I'm President of one and a member in two others so it keeps me busy.
I have also included a snapshot of my car with it's custom plate (COZY). How's that for advertising? Reaction on the highway is mixed. Some people just give strange looks. but fellow EAAers with the gold wings in their windows always smile and give a thumbs-ups!
The reason you don't hear much from me is definitely a reflection on the quality of the plans and the abundance of Long EZ builders here. The best of building is the friends you make along the way!
Thank you for taking the time to send information on the nose gear modifications. Since I have already installed the gear, I may only use the new fork. Brock Mfg. says they are still working on the fork assembly.
Work is progressing surely but slowly on Cozy #221. I had an "open house" meetlng at the request of our local chapter. Everyone was suitably impressed and are looking forward to seen the Cozy airborne. Thanks again, Nat, for your design and assistance.
Thanks for the Mark IV (serial #120) plans. I guess I should have written sooner, but I have been having too much fun pouring over them. I am really pleased with the quality of the plans. I have read them through once, and am just now starting on my second read.
I made contact with local EAA chapter 388. 1 believe that I am the first Mark IV builder in the group, but fortunately for me there are several Varieze and Long EZ builders and fliers in the group. The past president of the chapter has been flying his Long EZ for about 3 years now, and works for the company I do. We have been meeting at lunch to schmooz, and I have been learning a lot from him.
Starting April 13, 1 have a 6 weeks sabbatical from work, during which I plan to get my shop ready to work on my airplane. Again, thanks for the great plans, and thanks for what looks like a great design. I am already having fun.
Wesley R. Witte
Cozy #267 has over 200 hours on it now and is flying great! After all these hours I still get excited each time I fly.
Enclosed is a check for renewal of the newsletter. It is very well done but I would be more than happy to increase the subscription rate if you would be able to include more construction pictures. Thanks again for your plans.
Happy New Year! Am happy to report that both my Cozy and John Kroboth's are beginning to look like airplanes, and not boats as everyone thought we were building. Much progress has been made, as the only major structures left to finish are the canopies and strakes. The rest is ready for fill or is being sanded. I figure that we're about 90% complete with only 50% left to finish. I don't expect to make Sun & Fun, but both of us should be at Oshkosh. If so, and if joined by Tom Gross, there will be three Cozys there from the same town!!