ISSUE # 29
NEWS: Jack Skarratt (Varga 2150A, N5600B) has his airplane almost back together but in his search for landing gear parts he found that the lower strut from a Bonanza has the same axle size and very nearly the same vertical strut tube size. He's still investigating the possibilities and I will let you know what he comes up with as soon as I know.
New owner Tim Keith-Lucas (Varga 2150A, N4614V) had a ground mishap and bent his nose gear and engine mount. He was able to borrow Rolf Lehman's fixture for repair of the engine mount but is looking for design data and/or parts to repair his lower nose gear strut. I am trying to complete a sketch from a damaged nose gear that I have but if any of you can help him with parts or information he can be reached at (615) 598-1317 and I'm sure he'll be thankful.
He said he doesn't know what he's going to do with it yet but Bob Thornton bought Bill Morrisey's Model 2000 Type Certificate.
Hart Jewell sent an excellent photo instruction manual on how to service Varga landing gear. Let me know if you want to borrow it.
The January 1997 issue of PRIVATE PILOT magazine is on the stands and features an article about the Varga by David R. Hughes. The article is good and I hope you'll buy the magazine and read it but it does have some errors that I think should be pointed out.
He had no way of knowing unless he asked me, but the author wrote that "It weighs about 1125 pounds empty...". Most Varga 2150A airplanes went out the door at around 1175 pounds and the Model 2180's were about 50 pounds heavier. I believe most Morriseys and Shinns were delivered without paint and with a minimum of upholstery and were closer to the lower empty weight. All Vargas were painted with 15-20 pounds of polyurethane and had a few more pounds of carpet and Naughahyde. Almost all Vargas were also delivered with a full gyro package along with at least one radio, a transponder and an intercom system.
The article also states that the two fuel tanks hold "...a total of 35 gallons (33 gallons are usable)." which is what it may say in the flight manual but you should know that from our flight tests on the model 2180 that, for all practical purposes, there is NO unusable fuel! If you run out of fuel you probably won't find more than a few drops left after you land.
The statement "On the left floor is the mechanical flap handle with 15 degree and 30 degree positions." should be ...with 12 degree and 24 degree positions.
An error that has been repeated in just about every Varga article I have read is that the nose wheel steering "...linkage disconnects when the nosegear extends after lift off." The truth is that the nose wheel steering IS NEVER DISENGAGED!
The incomplete information and inaccuracy of the story in a sidebar about spins is a more serious error because it may mislead people to believe there is a spin problem with the Model 2150A when there isn't. The spin test referred to in the article was not done on the model 2150A but only on the model 2180. Although we couldn't afford to certify the Varga as aerobatic at the time, a prerequisite to aerobatic certification was that the airplane had to be either recoverable from a six turn spin or demonstrated to be "characteristically incapable of spinning". A spin test had to be done for each possible aircraft configuration, including power off and power on, no flaps, half flaps and full flaps, left turn and right turn and most forward CG and most aft CG all at full gross weight. For example, a power off/no flaps/left turn/aft CG spin entry would be succeeded by a power off/no flaps/right turn/aft CG spin entry which would be succeeded by a power off/half flaps/left turn/aft CG spin entry which would then be succeeded by power off/half flaps/right turn/aft CG spin entry and so on and so on. As you might expect, the most critical stall and spin tests are for the most aft CG condition. If I remember correctly, for the aft CG series, the model 2180 flight test airplane was loaded at slightly more than the maximum gross weight of 1817 lbs., the CG was almost half an inch aft of the aft CG limit of 17.5" (17.8" or 17.9") and elevator travel had been increased to 20 degrees up instead of the normal 16 degree up limit for the standard aircraft. All of the normal limits were exceeded to insure that the airplane would be safe in the most likely "out-of rig" situation. For example, 20 degrees up elevator was a mechanical limit which was the most travel you could get before the rear stick hit the back seat. The DER test pilot that we hired went through the whole spin series and was unable to get the airplane to spin in any configuration and it would spiral out of each spin entry within 3/4 to 1 turn. We expected FAA test pilot Carl Jacobsen to get the same result. Carl's next to last test was a power on/full flap/left turn/aft CG spin entry and the airplane finally did enter a spin and would not recover without the spin chute. After some discussion it was clear that Varga Aircraft couldn't afford the time or commit the resources necessary to make the airplane spinnable or incapable of spins so it was decided to continue certification with the airplane placarded against spins. I re-rigged the spin chute system, returned the elevator to its normal up travel of 16 degrees and the next morning Carl went up and did the last, and uneventful, one turn spin test. This was the last of the required flight tests and shortly afterward we received the FAA type certificate for the model 2180. Whenever I tell this story, I add that this model 2180 flight test aircraft was configured to exceed standard weight, CG and flight control limits. My experience tells me that in a Varga, Shinn or Morrisey with properly rigged flight controls, loaded within normal weight and CG limits and a reasonable distance above the ground, IT IS EXTREMELY UNLIKELY THAT YOU WILL EVER EXPERIENCE AN UNRECOVERABLE SPIN.
This same sidebar also noted that the Varga 2180 "...has a larger rudder and vertical tail than are needed for takeoff performance. This airplane, on the other hand, easily entered a one turn spin and recovered nicely during tests. Apparently, the larger tail and rudder enhanced the spin characteristics of the airplane." It is true that about half a square foot was added to the rudder but the vertical tail is not larger. It was hoped that the larger rudder would improve spin recovery but, as noted above, it appeared to make no difference. The larger rudder also didn't seem to make much difference in takeoff performance with the tricycle gear model 2180 but it did appear to improve directional control on both takeoff and landing of the taildragger.
In another sidebar labeled "Varga History", it was said that model 2180's were equipped with a Lycoming O-360-A2D. The model 2180 airplane was equipped with an O-360-A1D hollow crankshaft engine (for constant speed props) which we found out had to be placarded against continuous operation at certain RPM's when used with a fixed pitch Sensenich propeller. To avoid this restriction, all other production model 2180's had an O-360-A4D solid crankshaft engine installed. This sidebar also said that "...Bill Morrisey again acquired the type certificates." Bill already had the type certificate to his model 2000, but the tooling, inventory, 2150A type certificate, 2180 type certificate and the Taildragger STC that Varga Aircraft owned was sold to Jim Smith (Montanair) in the summer of 1986 and moved to Kalispell, Montana. As I have mentioned before in this newsletter, all that stuff was bought from Jim Smith a few years ago by Loren Perry of Augusta, Georgia who is now trying to sell it again.
As I said, it is a good article that will provide lots of valuable information to those readers that are unfamiliar with Bill Morrisey's fine airplane but I thought you, as owners, would appreciate it if I cleared up some of the discrepancies that I noted.
Copperstate: There were lots of interesting airplanes and activities at Copperstate this year but only 1 Varga, a Shinn and my airplane. On Saturday, Dave Wells brought N5068V from Deer Valley and Helen Buelen flew her Shinn (N5128V) down from Falcon Field. Walter Ruehle (Varga 2150A, N4603V) flew down Saturday from Colorado on an airliner and we spent some time talking about his recent landing gear maintenance experiences before he had to leave to catch his flight home. Jack Adams (Varga 2150A, N5073V) came down from Massachusetts for the weekend which gave us lots of time to chat about the improvements he's making to his airplane.
PLANES & PARTS:
Harry Jones found a source for the 12-24 X 1/4 inch long screws that are used at the top of the landing gear. He sent a gift of 200 12-24 X 1/4" screws and 100 12-24 X 1/2" long screws to me. I will send some to you if you need them. Del Lutz found 8 Continental Engine oil caps and sent them to me. They seem to fit the Varga fuel tank perfectly. They are painted yellow and may need a new rubber gasket but if you need one you can paint it black and install a new gasket and the price is right (free!). I also have a bunch of Varga key fobs that George Shaw sent to me over a year ago. Just give me a call or drop me a post card to let me know if you need any of the above items and I will send them to you.
VARGAS FOR SALE
I apologize to John Ellis of Jackson, MO for getting his phone number wrong in the last newsletter. He has VARGA 2150A N7066T VAC105-78 For Sale for $30,000. It has been converted to a taildragger with a 210hp Continental engine. John says he has a taildragger STC but it is certified Experimental (Exhibition Catagory) due to the engine change which he was unable to get STC'd. He says it is a 10/10 In and Out and he will send details upon request. His correct phone is (573) 243-3502.
TRADE-A-PLANE, SECOND NOVEMBER ISSUES, 1996:
1979 VARGA, 1090TTSN, COLLINS Microline Nav/Com, KI206 Indicator (glideslope), Collins GLS350 glideslope receiver, KT76A transponder, Apollo 618 loran, asking $38,500. J.M. Aircraft, 704, 326-8900; Fax 8902.tf
MEMBERS & OWNERS:
VG-21 Membership: A $20 annual donation will cover all the printing and mailing costs for at least four issues a year and will help pay for return phone calls, letters and postage when you have questions or comments that require a quick or personal response. Beery VG-21 Newsletters: $10 covers most of the printing and mailing costs for all issues. Old Bishop VG-21 Newsletters: $2.00 per issue (includes postage).
For those of you who don't know, I am the former Varga Aircraft Corporation engineering manager (1975-1982) and may be able to help you with a problem. I can be reached at:
2062 West Gila
Chandler, Arizona 85224
You may also be able to find me at hanger A9 at Falcon Field in Mesa.
Tom O'Hara of Creston, California bought Frank Gulick's 2150A, N8262J, who traded up (or down?) to a Bonanza. Tom, Bob Foote (Shinn N5135V) and Wally Nissan (Varga N8266J) now all have their 2150A's based at Paso Robles Airport.
Jim Clack of Hampton, Georgia has become a new VG-21 member. Jim has a Varga 2150A that was originally owned by Mr. Varga and was recowled by Curt LoPresti to give the airplane an extra 10 MPH.
Gerald Eldridge of Big Fork, Montana bought Vic Barrett's Model 2180, N56001.
For you WWII buffs, Myron Buswell (Shinn 2150A, N5131V) sent some information about his experiences as B-24 pilot in the Southwest Pacific. If you're interested, I'll send copies to you or you can call Myron in Independence, Oregon at (503) 838-3737.
The subject of elevator trim came up again a few times since the last newsletter.
Dave Miner has just purchased Varga 2150A, N4639V and said he found that the nose down trim pressures with someone in the back seat seemed to be too high. Another of Dave's observations was that with someone in the back seat and the trim handle in the green, he had to hold the stick forward on climb-out to preclude a stall.
I got a letter from Reg Engleson of Taber, Alberta Canada who said he installed 1/4" shim and "It sure cured the not being able to get the nose down trim problem. But now I don't seem to have enough up elevator travel, pulling the stick back to the stops still does not flatten out the flare, without power being added. Should I adjust the elevator for more up travel?"
Jack Adams said he'd added a shim to his front horizontal stabilizer mount to reduce the force needed to turn the trim handle. He says his trim forces are lower but on landing with a forward CG his ability to flare was affected. The airplane still won't hold a proper nose down trim with someone in the back seat so I suspect his trim clutch may need repair.
From the time I started working at Varga Aircraft in 1975, there have been complaints about the force required to turn the trim crank when there was a passenger and/or baggage in the back. Most people thought that when the crank got hard to turn, they had reached a stop and were afraid to turn it any farther for fear of breaking something. Occasionally, when the airplane wouldn't hold a trim position, there was a problem with slipping trim clutch and it would have to be replaced or repaired. Usually though, after the new owner was told push the stick forward while they turned the crank and/or turn a little harder, we didn't hear from them again. Since it didn't appear to be a major problem to us and an explanation usually solved any complaints, we didn't do anything to fix it. Long before we went out of business, I had a solution but I also had many more urgent problems that kept my solution on the back burner until I built my own airplane.
Before discussing the Varga pitch trim system design in particular, it may be helpful to first discuss airplane pitch control in general.
All airplanes have Center of Gravity (CG) limits that allow the airplane to maintain stable flight characteristics from takeoff to landing within a reasonable range of speed and loading conditions. These loading conditions range from the most forward CG and weight to the most aft CG and weight that a pilot is likely to see in that particular aircraft. As we all learned when we got our licenses, the pilot has the option of adjusting fuel, passenger and baggage to stay within those CG and weight limits. If the airplane is loaded too far forward, the elevator (or stabilator) won't have enough power to flare on a landing and if the weight is too far aft the airplane may become unstable and/or uncontrollable in flight.
Elevator travel and trim systems are designed to control an airplane at both ends of this CG range but not necessarily beyond specified limits. Elevator up travel and the forward CG limit is usually set so that there is just enough control to get the nose up and flare the airplane on landing and not have too much elevator authority at the aft CG limit. In the Varga, up elevator travel is also limited to help provide its excellent stall characteristics and spin resistance throughout its CG range. If elevator up travel is reduced to less than 16 degrees (+1 degree), the Varga may not flare properly on landing with a most forward CG and if up elevator travel is increased to more than 16 degrees, at the aft CG limit, the stall may become more abrupt and the airplane more likely to enter a spin. Loading the Varga forward of the 10.4" limit or aft of the 17.5" limit has an effect similar to decreasing or increasing elevator travel respectively.
The most common longitudinal or pitch trim systems have either movable trim tabs on the elevator/stabilator or they adjust the horizontal stabilizer angle. The Varga uses a cable and spring system to pre-load the stick fore or aft so that you won't feel the extra up and down air loads on the tail with different CG conditions or when trimming to new airspeeds. Many pitch trim systems use high ratio wheel or crank mechanisms that may require several turns for relatively small changes in pitch and the pilot feels almost no change in trim forces at his hand. The Varga low ratio trim system does the same thing in less than one turn and, unless s/he pushes or pulls on the stick at the same time s/he is trimming, the pilot will feel most of the air loads on the elevator transmitted to the trim crank.
The Morrisey and Shinn trim system came with a full size General Motors (GM) window crank handle. Before I got there, someone at Varga decided that the throttle and trim handles were too close together and changed the trim crank to a GM vent window crank which is about half as long as the full size crank. This almost doubled the trim forces but the FAA still found the forces within an acceptable range so the change was approved.
As I noted in Newsletter #22 each 1/16" shim added to the forward stabilizer attach bracket increases its angle of incidence relative to the wing (and the rest of the airplane) by 0.28 degrees. Unless readjusted, the shim also increases the elevator travel by about the same amount. If you add a 1/4" shim without readjusting the elevator, you will increase elevator travel by more than one degree (1.12). This will obviously improve control at the forward CG limit, will probably reduce the force needed to turn the trim handle and some owners have even reported increases in top speed but it may make the stallmore abrupt and make an inadvertent spin entry more likely when the airplane is loaded at or near the aft CG limit.
All Varga taildraggers are somewhat tail heavy and easy to load beyond the aft CG limit if the operator isn't careful. A Varga taildragger owner once reported that he would occasionally experience an unexpected whip stall when he was loaded at (or aft of?) the rear CG limit.
It should also be noted that it is highly unlikely that you can ever load a tricycle gear Varga 2150A to it's forward CG limit. While at Varga, I calculated the weight and balance of almost every airplane that we delivered. I doubt that the calculated most forward CG limit was ever less than 11.5 inches. In order to flight test the Model 2180 at the 10.4" forward CG limit, I had to put over 100 lbs. of lead on top of the battery box. In other words, although it is more than adequate, the Varga's CG range is probably shifted aft more than it could be. It's too costly and too much work for most Varga owners, but it appears that moving the engine forward about 2 inches might reduce the trim forces for most normal loading situations and even increase the baggage capacity to more than 50 lbs. (within maximum weight limitations, of course).
I think the tricycle gear Varga is one of the few airplanes of any type that you can load both seats and the baggage area and fill both tanks and still be within weight and CG limits.
Reg Engleson also wanted to know the actual load factor the Varga was built for.
Normal category load: 1817 lbs. X 3.8G = 6905 lbs.
Utility category load: 1570 lbs. X 4.4G = 6908 lbs.
As you can see, there is no real difference in the limit loads imposed on the airplane in either category but in the Utility category at a reduced weight, you can pull more G's and the CG is more likely to be farther forward because in the Varga you must solo from the front seat and at 1570# you will have to give up fuel, baggage or a passenger to be within the weight limit and all of those things move the CG aft.
If it was certifiable for the aerobatic category you could divide 6905 lbs. by 6.0G and get a weight of 1156 lbs. which is probably less than the empty weight of most Vargas. From load tests that were done for certification of the taildragger and the model 2180 and informal load tests that were done in Montana, I know that most major structural parts of the airplane are capable of higher G loadings but until formal load and flight tests are done, no one will really ever know. Although you may be willing to do aerobatics, it will always be somewhat risky to find out on your own if the Varga is strong enough to handle the loads.
I'm a little disappointed that the newly chromed cylinders on my airplane still haven't broken in yet after more than 35 hours of flight time, but otherwise the engine is working fine. It still burns a quart of oil every 6 to 8 hours. That is about twice the oil consumption I had before the engine overhaul. I am also leaking a little oil from the crankshaft end plug. Oil seeps out and coats the front of the prop. Lycon has replaced the plug once and it doesn't leak as much but they said to bring it back and they'll try again. My fuel pressure gage recently started fluctuating rapidly from 20 to 30 PSI. Lycon suggested that the new mechanical fuel pump that they just installed may be bad I'll have to take it back to be replaced.