Q-talk 84 - LETTERS
- Category: Q-Talk Articles
- Published: Tuesday, 31 October 2000 06:11
- Written by Tom Moore
- Hits: 2869
This is the second part of Lynn French's article started in the last issue.
Concerning wing incidence, my canard was originally mounted at about 1/4 degree positive to the main wing. Based on reader feedback this hardly seemed enough. I contacted several builders who had increased the angle of incidence and were very pleased with the results. Since I was at a stage where this change would be relatively easy to do I decided to take the plunge. After a week of part time work I raised the incidence to 1.75 degrees positive. I used the method and calculations posted in a previous newsletter by Sam Hoskins - it worked out quite well. By the way, I purchased a digital Super Level that has resolution to 1/10 degree that proved to be very valuable for many other phases of the project as well. On a similar note, I have a couple of bubble levels mounted on the aircraft plus other known references for future leveling of the aircraft.
Some other changes include doubling the thickness of the phenolic bushings for the aileron and elevator torque tubes for longer wear. I implemented the quick release forward tilt canopy hinges posted in a previous newsletter. I installed the EIS engine information system by Grand Rapids Technologies in the panel to replace many of the engine instruments in hopes of reducing clutter. For the same reasons, I used switch/breaker combinations for circuit protection.
On the engine side of things, I built the fiberglass plenum type baffles detailed by Jon Finley in a previous newsletter. It worked out very well and probably took no more time than the plans aluminum baffle system plus getting the expected improvements in cooling. In an effort to reduce problems with components in the mag box area, I modified the mag box and installed the B&C starter. I also blanked off the rear alternator port and mounted the alternator up front. I had a hub machined, which would fit between the engine flange and prop extension to drive the alternator. The hub has a rearward offset flange of about 2 inches where the V-belt groove is machined. This avoids having to bump the cowl to make the alternator fit and prevents interference with the fiberglass plenum inlets. Someday I may try to eliminate one of the mags and install electronic ignition, but not for now. Because of the sag problem of many engine installations, I had 4 tapered aluminum supports made for the backside of the engine mount standoffs. These "modified washers" replace the cheap pieces of tin provided as backing plates by QAC. Mine are about 1-1/2 inches in diameter at the base and 1-1/4" thick. They are tapered from the head of the engine mount bolt out to the firewall. The thought is to spread the load out over more square inches of the firewall. Of course longer engine mount bolts were then needed. I used CamLoc fasteners on the cowling. When doing this, I found a source for an adjustable receptacle that can be used such that one stud length can be used for several different thickness of material. These receptacles are also lighter than the standard 212-N type, but as usual, the premium to pay for this convenience and weight savings is price. I can look up the source for these if anybody is interested; they are not in Aircraft Spruce or Wicks. I am using a cone type air filter from K&N for my O-200. I was adamant about filtering the intake air and this seems to work well. Bob Farnam has implemented this filter and likes it. It is rated at 207 CFM, which is more than enough and exceeds the standard Bracket filter often used on these engines.
For finishing, I used the Poly Fiber system. Their SuperFil is very easy to use and sands easily. The instructions call for applying thin layers and sanding them down. You will have to do this several times to chase out the high and low spots. This takes forever, so what works best for me is to apply one thick coat and sand until the high spots start to show. Gets it all over with in one session. I start the sanding with 40 grit and gradually work down to 180 as the high spots can be seen under the surface. The UV Smooth Prime is about as easy to apply as you can get. It cleans up with water and sands nicely. I roll on the first three coats to get the pinholes out. After sanding these coats, I spray on four more coats and sand down with 240 grit. This part works well per their instructions.
My aircraft has not been inspected or flown yet, but if anyone would like greater detail on any of the things mentioned here, I would be happy to help. As I have eluded, previous builders have covered many of these topics as well.
Lynn J. French
Broken Bow, NE
When I began my conversion my Q2 had 380 hours - T-tail, reflexor, GU canard, an electric T&B, Whelen nav/strobe lights, transponder, single nav/com, Revmaster 2100DQ w/75HP heads and weighed 640 lbs. In my opinion, it was underpowered. I did not care for the Revmaster and decided to replace it.
My conversion objective was to find an affordable power plant that I trusted. My few design goals included the ability to fly high (15,000'), good cruise/climb performance (165 mph (at altitude), 1500 ft/min) and low cost. Obviously these are pretty easy objectives to reach with a Q-200. I had been following the Subaru movement for a number of years and really liked what I had observed. I lived in the same city as Bud Clark (Helena, MT) during the first half of the 90's. This made it easy for me to follow the work that the Clark brothers were undertaking with their direct drive Subaru powered Dragonfly's. I found that the direct drive Subaru EA-81's had been serving the gyrocopter group very reliably for many years. I am told that an engine experiences much higher gyroscopic propeller loads on a gyrocopter than a typical aircraft will ever experience and there had not been any reports of crankshaft problems on the direct-drive gyrocopters. The final straw was meeting Roger Enns. Roger was flying an EA-81 direct drive turbo, similar to Reg Clark's setup. Roger was an engineer with Orenda, was very pleased with his Subaru conversion, and was willing to help me with the conversion. I don't think I could have ever gotten through the process without Roger and owe him a huge debt for all his assistance.
The EA-81 is an 1800 cc horizontally opposed four-cylinder engine. This engine is a single cam engine with pushrod actuated overhead valves and comes with either solid or hydraulic lifters. The American engines have a book output of 73 hp; the Japanese engines (dual carb, different cam, larger valves) book output is near 100 hp. The engine is typically used in aviation with a propeller speed reduction unit (PSRU) to allow the engine to operate in the 5000-6000 rpm range and produce in excess of 100 hp (I believe NSI markets theirs as 120 hp). In the direct drive turbo configuration the engine typically operates in the 3200-4000 rpm range and can be expected to produce 80-90 hp (possibly more). My typical cruise rpm is 3400-3500. These engines were available in the 1983-1985 model vehicles with several variations (turbo, carb, solid/hydraulic lifters, etc...).
In 1996 I purchased a 1984 Subaru GL wagon with 120,000 miles. The engine had been rebuilt 20,000 miles previous and was the EA-81 1800cc pushrod engine with solid lifters that I wanted to use in my Q2. Sadly, in 1997 the clutch in this car died. It was a difficult decision, but with my wife's help I decided that I should remove the engine, junk the car, and begin converting the engine for use in my Q2. The engine is completely stock internally - I did not change a single item. Many people are using aftermarket cams and raising the compression ratio to increase horsepower.
The following outlines the changes that I made to the engine.
1. Trim bell housing.
2. Trim oil dipstick and guide.
3. Drill and tap 3/8" NPT hole in case for turbo oil return. Hole is located to the left of the oil pump and just above the oil pan.
4. Drill and tap coolant drain holes in both heads to 1/4" NPT. One port provides coolant to the turbo, the other port is plugged.
5. File lips around the two aft cylinder head attach bolts. This is done to avoid interference with the motor mount.
6. Weld a piece of steel tubing to the oil pan and tap to 1/8" NPT for oil temperature sender.
7. Machine power steering pulley from water pump pulley.
8. Drill and tap end of crankshaft for prop hub safety bolt.
The motor mount is comprised of five separate pieces. Two lower pieces bolt to the automotive motor mount location on the bottom of the engine. Two upper pieces bolt to two head bolts. These four pieces then bolt to the tube structure that attaches to the firewall. Rubber vibration dampers are installed between the tube structure and four mounting tabs. The mounting tabs were constructed of 1/8" stainless steel. The tube structure is constructed of 4130 tubing - 5/8" diameter with .065" wall. Several other builders are using these same materials without problems so I elected to follow their lead rather than design something new. I used flat rubber vibration dampers from McMaster-Carr. I do not think they do much for vibration isolation and would recommend using a more typical approach.
The intake manifold is comprised of three pieces. An aluminum runner connects the carburetor to the turbo. This runner is bolted to the carburetor and to the turbo via flanges. A steel, Y shaped runner connects the turbo to the heads. The connection from turbo to runner uses a rubber hose. The runner is bolted to the intake port on the head. The runner is cut into two pieces and connected with a rubber hose to allow expansion and contraction of the engine. The aluminum runner was constructed from 1.5" aluminum and is V shaped (due to twin barrels of the Weber Carburetor). The runner from turbo to engine is constructed of 1.5" mild steel tubing with .050" wall.
The engine is designed for hot coolant to flow out the engine through the intake manifold (keeping it warm). I chose to build the intake flanges out of 1/8" 4130 steel. Each flange has the intake runner and a 5/8" O.D. tube (for the coolant to flow through) welded to it.
1-5/8" mild steel tubing with .050" wall thickness from JC Whitney was used to fabricate the exhaust. It wraps around the back of the oil pan, joins into a larger, 1.75" tube and then enters the turbo. From the turbo, the exhaust flows through a 2" mild steel tube and is vented overboard on the bottom left side. A muffler is not used. The engine is relatively quiet but installation of a muffler would serve to make for a very quiet airplane. I intend to pursue this at a later date.
The flanges for the head exhaust outlet and turbo inlet were fabricated using 1/8" 4130 plate.
The turbocharger is from a 1988 EA-82 engine (model years 1985-1988). This turbo includes a water-cooled housing instead of an oil-cooled housing like the EA-81 turbocharged engines. The standard banjo fittings were utilized for all oil and coolant lines. A hole was drilled and tapped in the case just above the oil pan for oil return from the turbo.
A braided steel hose is utilized to supply oil to the turbo. An aluminum manifold was fabricated to allow adapting an oil pressure sender to this oil supply line.
This turbocharger includes an automatic wastegate limiting manifold pressure to approximately 7.5 psi. This means that this turbocharger/wastegate combination will provide seal level pressure at altitudes greater than 20,000 ft. The disadvantage of retaining the stock system is that of the in part throttle conditions, the turbo may be working only to restore pressure lost due to the pressure drop across the partially closed throttle. Ideally, the turbocharger should only be employed after wide-open throttle has been reached. I decided to operate the wastegate manually to avoid making the turbo work at partial throttle settings. This requires great caution on my part as I am the only pressure control and the wastegate is rather sensitive. A better, although more complex, system would be to incorporate the automatic wastegate into the manual control system. In this fashion, over boost protection and manual control would both exist.
In the automotive application this turbo is used with a fuel injection system that does not see high manifold vacuum. Due to this a carbon oil seal is required to prevent the turbo from sucking oil through the seal at high manifold vacuum.
To date, I have limited myself to 7 psi of boost.
Part two of Jon's article will be in the next issue.
Jon Finley, Apple Valley, MN
I went the expensive route to protect my brake lines and make them easily repairable. I stopped by McDonalds and got a handful of straws. I then fit the straws together; spot epoxied them to the legs of my Tri-Q gear and put a layer of glass over them. Then all you have to do is slide the brake line tubing down through the straws.
Jerry Marstall, Ashville, NC
The other part of the equation is for making the Q behave on the ground. I reasoned that there were several other problems inherent in the design of the steering. One is that without toe brakes, Quickie Aircraft couldn't use a full swivel tailwheel and was forced to provide a lot of degrees of tailwheel movement to make ramp maneuvering acceptable. This large movement of the tailwheel makes the steering sensitive and the airplane twitchy on the runway at high speed. Many fast landing taildraggers use either a locking tailwheel for landings and takeoffs (P-51) or a limited range tailwheel (S-51) limited in some cases to as little as +/- 5 degrees. Quickie also chose to leave off the usual tailwheel springs which almost all other taildraggers use. The springs accomplish two things. They soften the inputs to the tailwheel so that there is less tendency for the tailwheel to break loose and skid, and also they help prevent the airplane from darting to the side if there is other than neutral rudder at touchdown, such as when landing crosswind.
Because of these reasons, I decided to install a full swivel tailwheel for easy ramp maneuvering and at the same time to reduce its range of movement to about half that of the original to reduce high-speed twitchiness. And I installed conventional springs to soften the steering.
Above is a picture of Bob's bell crank where he separates the rudder and tailwheel cables inside the tailcone.
Below you can see the two separate cables exiting the tail.
Another problem in the original design was the potential loss of both tailwheel control and rudder control if the tailspring were to break, not at all uncommon with this airplane. I installed a Dragonfly spring for its extra strength and split the cables for redundancy. A substantial bellcrank is installed on the floor of the tailcone just behind FS 120. The rudder cables go to the bellcrank, which takes the considerable loads, which can be developed in the rudder cables, instead of transferring the loads to the wimpy, little bearing at the bottom of the rudder. The cables then split with one set running directly to the tailwheel through conventional tailwheel springs, and the other set running directly to the rudder through turnbuckles.
The bottom line? I have a Q which behaves itself as a better than average taildragger. It is far more controllable on the ground than the Pacer that I used to own with Jim Ham. Because the spread between the wheels is so large and the brake steering so powerful, the airplane has to get seriously sideways before the brakes can't save it. Our old Pacer could easily get out of shape with the CG moving outside of the wheel, because of the narrow gear. The Q200 is more sensitive to brake steering than a narrow tread taildragger, but not so much that control can't be easily learned, especially if the brakes are smooth.
In summary, there's nothing going on here that's new to the world of taildraggers. All I have really done is to make the steering and braking systems on the Quickie just like all the other modern taildraggers in the world. These systems have evolved to where they are today for one good reason - they work. It works on a Quickie too.
Bob Farnam, Livermore, CA
I flew to Waukegan, IL for Mother's Day and parked my Q-200 at the big corporate jet terminal. Very upscale. I told the sweet young thing behind the counter that I need tiedown for the evening and fuel tomorrow for my experimental. She was taking down the usual information and asked, "What type of plane is it?" I said, "It's a Quickie." She looked up and blinked and had a funny look on her face. "Huh?"
I said, "That's what it is, a Quickie." She started looking around the room for something. I think she thought she was on Candid Camera and was looking for the camera.
Sam Hoskins, Murphysboro, IL
There have been several discussions lately on aileron trim. Here's a picture of what I think is the simplest aileron trim around. It's simply a piece of elastic with Velcro on each end. To use it, attach one end to the side of the center console. Wrap it around the stick and attach to the other end. If it isn't quite right, you just stretch (or unstretch) the elastic a little and reattach. There is no permanent connection to the control system, so overriding it is pretty easy (just pull it off).
Paul A Fisher, Taylor Ridge, IL
Paul has over 800 hours on his very functional trim device.
The following was taken off the Q-LIST. It was provided by Mike Dwyer on what he would change if he had a chance to do his Q-200 project over again.
Many of you know that I am a staunch supporter of "build it to the plans". This will allow you to put the lightest airplane in the air in the least amount of time. After putting 15 years and over 900 hours of flying time on my Q-200 I have some opinions on some areas where built to plans isn't the best.
1) The tailwheel fiberglass spring is woefully undersize, double its diameter with glass and change the tailwheel axle to a 1/4 bolt (I keep bending my 3/16" AN3 bolt).
2) The original disk brake system where the caliper is suspended on one side isn't any good. I spent more time tweaking it than anything else on the plane. See QBA articles for a much better system of having the caliper float on a pin. After changing it my brakes are smooth and nice. The brakes have very much less braking authority now (sufficient though), I suspect the previous system was twisting, bending and grabbing. Toward the end of my use of the old system upon landing the brakes were so bad that the plane vibrated violently and the canard bounced up and down (diminishing as I let go of the brakes). Be ready on those first flights, if it starts.
3) The main tank fuel sender, don't use the clear tubing with a float. If you were in a crash your leg would probably break the tube (gets brittle with age) and if you ended up upside down you'd have gas flowing out the now cracked tube into your face. You can figure out the rest. I'm building a Capacitive gauge that will output to a 12V meter, will report how well it works later.
4) Build a water filter into the fuel filler neck. These $10 funnels have a removable Teflon filter element that won't let water or junk thru.
5) Make the wheel pant a little wider to allow a change to the axle location. As the plane ages the canard creeps making the wheels not straight up and down. See http://www.geocities.com/CapeCanaveral/Hall/1653/r2.html to see where mine got to after 15 years. The change in ground handling from the axle hole center hitting the ground in the center of the plane to being in line with the other axle hole was dramatic. The Q-200 is back to being like it's on rails again.
Mike Dwyer, Florida
Tom Moore's Q-200. It's amazing what this plane will do with an O-200 on the front.
You can order a PDF or printed copy of Q-talk #84 by using the Q-talk Back Issue Order Page.