some Varieze questions - looking for info and suggestions

Author Topic: some Varieze questions - looking for info and suggestions  (Read 34393 times)

0 Members and 1 Guest are viewing this topic.

Offline flyoz

  • Newbie
  • *
  • Posts: 28
    • View Profile
Re: some Varieze questions - looking for info and suggestions
« Reply #15 on: June 01, 2010, 01:55:30 AM »
Good point
Maybe the pin is in the root of the wing and the recepticle can be bonded into the strake once the wing has been levelled etc
Most accident photos seem to suggest the strakes remain intact so the pin will be an intergral part of the wing attach
I have roughed out a sort of combination of box spar near the connecting point then back to a C section further towards the tip
The geometry seems to allow for that
The Varieze wing worked just fine without a spar all the way to the tip and from what i can see that should be ok
I still need to move the root back 2.4 Inches (60 mm) to make it work ( but i can move the seats forward 2 inches without changing the overall sizing )
I have done a rough calc and the change to the Cof G is very small
The aerodynamic change is small too if you consider the tip stays where it is
I have done some work on the main wing spar and it would be very close to the original and still have the hard points as the Long built it
So far it looks ok

Offline Tom

  • Newbie
  • *
  • Posts: 125
    • View Profile
Re: some Varieze questions - looking for info and suggestions
« Reply #16 on: June 01, 2010, 04:31:44 PM »
I am an Aeronautical Engineer, and I can tell you the only thing that the "test to destruction" on the liked page proves is the the structure will fail....

It clearly states the wings were loaded to "increase the twist"....

Im not sure why anyone would waste their time doing this as the results will be useless.

If you think you are smarter than Burt Rutan,  give him a call, Im sure he will want to hire you. Otherwise trust his designs and analysis.
He does seem to know what he is doing.

-Tom

Offline flyoz

  • Newbie
  • *
  • Posts: 28
    • View Profile
Re: some Varieze questions - looking for info and suggestions
« Reply #17 on: June 01, 2010, 09:10:59 PM »
The point is that even Burt Rutan decided to change the wing attach system when the product became the Long Ez .
Is the Varieze inferior ? I don’t think so - just different . Products evolve . The car you drive today has seatbelts , ABS and airbags- they did not in 1976 .
Part of the reason aircraft /  space  market is changing is because of entrepreneurs like Burt and the hundreds of experimental builders out there .
Every time I read his Varieze manual and check the drawings  I am inspired by the beauty of his designs .
I am simply trying to look at the design for myself .
Flyoz

Offline Joe Person

  • Newbie
  • *
  • Posts: 107
    • View Profile
Re: some Varieze questions - looking for info and suggestions
« Reply #18 on: June 01, 2010, 11:24:46 PM »
Just a few "FWIW's"

The VariEze wing attach configuration is very good, if built correctly.  The drawback is the requirement for correct overall fitting geometry and taper pin fit - Brock did a marvelous job on the fitting assemblies they built over the years.  Proper pin fit is essential to having a fitting assembly that is good for over 10 Gs.  One of the first things I did, back in the 80's, as part of beginning a VariEze, was to crunch some numbers, structures-wise (I are an engineer in the airplane biz myself).  I was not surprised to find a robust airframe.

The final version of of the Long-EZ wing configuration was the result of the conversion to an entire new wing planform, from the original Long-EZ prototype configuration.  As originally designed, the Long-EZ used VariEze wings (and fittings) on a wider centersection.  Flight testing revealed that this configuration was deficient in several ways, and after some iteration, Burt re-designed the main wing configuration for the Long-EZ, basing the wing attach configuration on the already designed & flying Defiant.
Joe Person
VariEze N79JN
Cozy #879 Under Construction
EAA Tech Counselor 4418
Bothell, WA (KPAE)

Offline flyoz

  • Newbie
  • *
  • Posts: 28
    • View Profile
Re: some Varieze questions - looking for info and suggestions
« Reply #19 on: June 02, 2010, 03:25:47 PM »
Thanks - i did some research on the Defiant
Some of my reasoning to change the wing attach on the Varieze .......
The wing attach fitting are hard to come by
They do not allow for any changes once fitted
The Defiant / long Ez system has proved reliable
Its actually easier to build
I am not quite there yet but i think its possible to build the Varieze
as it was designed ( aerodynamically ) and still change the wing attach
Flyoz



Offline Bill James

  • Moderator
  • Newbie
  • *****
  • Posts: 208
    • View Profile
Re: some Varieze questions - looking for info and suggestions
« Reply #20 on: June 02, 2010, 07:49:06 PM »
Since getting hooked on this Eze thing in 1975, I believe this is the third or fourth “fix the VariEze wing attach” series that I have enjoyed following. Please don’t stop, this is a good one. I appreciate the serious and deliberate progression through good questions. I will just slide in a couple of fellow-traveler comments.
My bottom line early -- I got started late building the plane. My labor-intensive business and building the plane benefitted from my not being on the computer until after getting the VariEze flying. Combined with several other factors like "The List", the plane was in the air several years earlier than projected. My experience with the VariEze fittings has been positive. Like most long term VariEze types, I feel little inclination to counter anyone's opinion on the fittings, but dont mind stating mine.
Like you, I also researched the wing fittings. One example, having seen some early VariEze drawings of tapered ‘through-the fuselage’ sailplane-type wing plug-ins, I considered trying to design and build those myself for a ‘better’ design and quick attach. What could go wrong?   :)

I corresponded for several years with a VairEze driver that had flown his plane 2400 hours and never paid hangar rent. His plane was kept at home in an enclosed trailer and was taken to the airport on Fridays and assembled and then tied down in ideal weather, or pushed into a friend’s hangar overnignt, and then packed up and trailered home on Sundays. With the simple supports he had, removing or attaching the wings and canard was 20 minute process. A few years ago I heard he was over 4000 hours. This and other examples helped to wrap up my research, with the awareness that the VariEze fittings have some significant advantages, like no adjustments, and as Joe Person points out above, are just an excellent design. And like all of the other elements of the plane, they must be built correctly and maintained properly. 

While I was building I was strongly encouraged to put LongEZ wings and spar on  my VariEze, as several others had done.
We have been traveling to see grandkids lately and my wife has mentioned several things she would have liked the plane to have, like a toilet, and popcorn machine. I have written articles on the advantages of the LongEZ, but having a LongEZ would not have solved this   :)

I still enjoy chewing on the "law of thermodynamics" that was recently explained to me because it covers so much of life... You always lose, you never win, and you have to play.  I am enjoying finding the exceptions...

With 14 years and a thousand takeoffs and landings, including the three flights last weekend, I believe and have experienced that to have an operationally friendly plane there are many other fish to fry besides the wing fittings.  And lots of these things can be done after the plane is flying. If a guy is interested in flying   :)

You play the game and you take your best shot. Good luck. Many qualified engineers looked into this and decided not to go into the wing fitting business. And so far no non-engineers have made their fortune with this either. I got some good advice once, from someone you would know. "If you can make a living doing anything else besides trying to sell stuff to people that build their own airplanes, do it.
Oh, now i remember the thought that triggered this response - To get yourself up and flying you only need one set of fittings. There are probably still some out there.
Good building  :)
Bill James, Fort Worth VariEze N95BJ
Downdraft Plenums, QuickCowls
There was supposed to be anhedral?
ATP, Society of Flight Test Engineers

Offline cloudman

  • Newbie
  • *
  • Posts: 51
    • View Profile
Re: some Varieze questions - looking for info and suggestions
« Reply #21 on: June 02, 2010, 09:22:18 PM »
I would be interested in hearing from other Varieze owners who have the plug-in wings that Fred Jiran built way back around the late 1970's. I understand that Burt did not like Fred making this wing/main spar attachment, but would like someone to confirm that this did actually take place. I have seen a few pictures on the internet of one rough looking installation.

I have no idea as to how many Variezes may be flying with this type of wing attachment.
Any info would be appreciated, since it seems like a valid way to attach.

Wayne Johnson Varieze N725EZ........flying since 1981

Offline Joe Person

  • Newbie
  • *
  • Posts: 107
    • View Profile
Re: some Varieze questions - looking for info and suggestions
« Reply #22 on: June 03, 2010, 10:28:34 AM »
Mike Drew's VEZ (based at KPAE & diagonally from my hangar) has the Jiran wings & associated attach system.  Having examined the configuration in detail, I find it more complicated and heavier than the per-plans VEZ wing attach scheme.  The Jiran attach configuration is more difficult to install the wing solo, does also not allow incidence adjustment, and would entail a fair bit of re-design to blend this configuration with plans-built wings (Jiran wings are hollow, with inner and outer skins, vs. the full-core foam in a plans-built wing).  From an overall configuration standpoint, I can see why this configuration was not pursued.
Joe Person
VariEze N79JN
Cozy #879 Under Construction
EAA Tech Counselor 4418
Bothell, WA (KPAE)

Offline flyoz

  • Newbie
  • *
  • Posts: 28
    • View Profile
Re: some Varieze questions - looking for info and suggestions
« Reply #23 on: June 03, 2010, 02:30:25 PM »
I appreciate the suggestions and reflections from both Joe and yourself
I have read the articles and comments about your aircraft and were really useful to those like myself  trying to understand this aircraft type
My wish list is fairly simple - I want to build essentially a single seater with a possibility of a passenger from time to time .Burt's philosopy was a light, small ,simple aircraft
I think he achieved that with a basic Varieze. I have no intention to build other than for myself .
I will have more questions as i go along :)
Thanks
Flyoz
 

Offline cloudman

  • Newbie
  • *
  • Posts: 51
    • View Profile
Re: some Varieze questions - looking for info and suggestions
« Reply #24 on: June 03, 2010, 03:59:34 PM »
Flyoz,
Your requirements for a single seat Varieze with an occassional passenger sounds like my Varieze with a C-85 with B & C starter.
I have pushed the max weight once in a while up to about 1125 #s. Flying to Jackpot , Nevada many years ago over the fourth of July with my 135 # WIB (wife in back) I limited my fuel to about two hours plus reserve of another hour or so. We had no trouble landing and taking off at Jackpot's approx 5000 ft altitude....by leaving in the morning before it got too hot.
So if you do not have to cruise much over 150mph TAS and burn 4 gallons per hour, the smaller C-85 is a good choice. My top TAS has varied with different props from around 175 to a bit over 180 mph
Flying south from the Seattle area to LA, I have stopped once for fuel at Red Bluff, CA. This is after being in the air around four hours. I am usually ready to get out for a break anyway, so stopping every 500 miles or so and adding 16 gallons of gas is usually appreciated.
Wayne Johnson .....Varieze N725EZ

Offline flyoz

  • Newbie
  • *
  • Posts: 28
    • View Profile
Re: some Varieze questions - looking for info and suggestions
« Reply #25 on: June 04, 2010, 03:36:16 PM »
Cloudman
Thanks for the info . It seems that your Varieze is just what you want .
The one overiding factor in my research is most people who have built a Varieze
with simplicity in mind have not been dissappointed . I am going to try to build as simply
as possible - i am progressing slowly - changing the drawings to CAD format and metric ( although i have retained the actual Inch dimensions )
Some would say redrawing in CAD is lost time but it allows me to understand the construction method more clearly i think .
What do you think of hand propping ?
Would you say an electric noselift is too much complication and a waste of time ?
Flyoz

Offline cloudman

  • Newbie
  • *
  • Posts: 51
    • View Profile
Re: some Varieze questions - looking for info and suggestions
« Reply #26 on: June 04, 2010, 08:05:18 PM »
Flyoz,
I know there are those out there that would rather not have a starter and not lose the weight. It's their choice, but not mine.
When my starter or battery are giving me a problem, I always have the nose up against something solid eg. the closed hanger
door, the rubber tire on a vehicle, etc. Once when I did not do that was the time I forgot to pull the throttle back to idle after flooding the engine. If it had caught, my Varieze would have gone on its way across the airport. This has happened to others with bad
results. Also, if I happen to run the main tanks dry and the prop stops prior to my figuring things out, I have a starter to
get me going again even at low altitude. We are humans and humans sometimes make mistakes.
I expect that a good battery, B & C starter, cable, etc will weigh a minimum of forty pounds.
I flew a three place Cozy that really needed an electric nose lift.....but it did not have one. I used most of my strength to lift it after adding gas with the nose down. A Varieze does not need any powered lift, unless a person is unable to lift much weight at all.
Good luck with your project !
Wayne Johnson.........

Offline Bill James

  • Moderator
  • Newbie
  • *****
  • Posts: 208
    • View Profile
Re: some Varieze questions - looking for info and suggestions
« Reply #27 on: June 04, 2010, 08:42:51 PM »
Hand propping. Hmmm.
Several months ago 4 yellow Piper Cubs stopped in here. Preparing to depart they did a mini-Blue Angles/Thunderbirds show. In unison they all chocked their planes, stood over the right tire with their left hand in the cockpit and propped the propeller with their right hands. They all started on the second pull and purred like kittens at what sounded like 100 rpm.
At Oshkosh a couple of years ago I stood by the throttle while Klaus started his dual LSI ignitioned VariEze. I think he said he said the plane had not run in 9 days. After his priming sequence it started on the second pull and purred at idle.
Approaching a thousand flights, I am still learning how to set up my 0-290 VariEze for the easiest start. For me this is mostly a priming thing. The bottom line from advisors is 3 prime strokes in winter and one in the summer, and then just start pulling. I will accept more advisors.
I have never seriously thought about adding a starter. If my engine would start within a dozen pulls, as it often does, I would never even think about a starter. The first time I started the engine it started on the first pull. If I am doing that airplane owner thing right, it should still start predictably most of the time. As with many things related to the VariEze, instead of building a DC-3 size Eze I use these elements as an incentive to be better.
Hand propping means that the pilot is very aware of the general engine condition, including compression. Working a little harder for our flight time, having awareness of good spark plugs, wires, mags, priming heads working (not stopped up), etc. is a more intimate thing.  I happen to be in a learning mode right now, recently starting the plane every day for about a week even if I didn’t fly. There is still some learning to do, along with checking some of the hardware. I have an impulse mag and one LSI electronic ignition with the red brick.
Since the LSI has a start bolt and a run bolt for the pickups, I have always expected it to be the significant player on hand starting rather than the Mag. During my present time of learning I found that the engine would start better on the one impulse mag with the LSI electronic ignition off. Once started, immediately after shut down with the switches, not the mixture cutoff, it started on the first pull with either the mag or EI or both. I am examining both sources of ignition for improvement.
In the past there have been a few episodes of trouble starting after landing and refueling for 20 minutes, maybe because of vapor lock. My best results there have been to leave the throttle at 1000 rpm and shut down with the switches, hoping for proper mixture still present and a one-prop start after refueling.
So much for positives and neutral opinions.
I think your comment might be more related to safety...?
I pay attention to those that have experience, good and bad. I try to be very deliberate. If I am interrupted during the preflight I start over. I also do the start the same way every time. On both main gear, I insert a quarter-inch steel rod through the strut and Matco brake disc, locking the brake. With the nose on the ground the plane won’t move at full throttle. I have never started with the throttle accidently left at full, but have moved the throttle to full with the steel pins in and it doesn’t move. The Matco disc already has three bolt holes drilled in them, I added 6 more, with no cracking or other issues.
I have observed folks hand prop until the engine pops and then shut off the mags and put the throttle open and the mixture off, and pull the prop backwards four revolutions, eight blades. This has resulted in an immediate start for me several times. This is also the place where we have to be very deliberate to re- set up the levers and switches to the correct positions.
On the other electric niceties, oh well, I have said enough here. Those might be the things I was thingking of that could be done after getting the plane in the air, if one still wants them.
Good building and flying-
« Last Edit: June 04, 2010, 08:52:46 PM by Bill James »
Bill James, Fort Worth VariEze N95BJ
Downdraft Plenums, QuickCowls
There was supposed to be anhedral?
ATP, Society of Flight Test Engineers

Offline cloudman

  • Newbie
  • *
  • Posts: 51
    • View Profile
Re: some Varieze questions - looking for info and suggestions
« Reply #28 on: June 05, 2010, 08:53:15 PM »
Flyoz and ............others
If you want to hand prop.....I don't recall if anyone has given instructions on the technique lately. Per Burt Rutan and watching him hand prop his Varieze years ago: First the prop is mounted to be on a compression stroke at the 10 o'clock-4 o'clock position. He stood to the right side of the prop, grabbed towards the tip at the 4 o'clock with the left hand and pulled upwards. This motion allowed him to step backwards and to the right away from the moving prop and air blast.

It works great if that's what you want to do. I doubt that there are few human pilots out there that have not made some sort of mental mistake at one point or another. I recall a Varieze pilot/builder and also Boeing engineer (if I recall correctly) hand propping his plane at Renton, WA airport some many years ago. His plane apparently had lots of throttle, got moving and crossed the active runway and crashied into a parked twin.

Having to hand prop is just one more way to potentially screw up !
I came close once......hand propping ...also once in a while I do not use my check list and forget a switch, setting the altimeter, etc.
I have been flying my Varieze for 29 years and still find new ways to mess up...It does seem that some of our new Varieze pilots are really having problems in keeping their plane in one piece.

Humans are not close to being perfect.....even those that think they are !!

Wayne Johnson

Offline flyoz

  • Newbie
  • *
  • Posts: 28
    • View Profile
Re: some Varieze questions - looking for info and suggestions
« Reply #29 on: June 06, 2010, 03:23:50 AM »
Thanks for a really useful discussion not only for myself but for others out there too .
Its adding to my notes .
Hand propping is an emotive issue i suppose (I have never hand propped an aircraft ).
I have never had an engine stop on me except on finals when the idle was not set right . I guess as a human you want that ability to actually be able to try and restart if you have to . But 40 Lbs is a lot of weight ... The idea of "dead" locking the brakes by putting holes in the discs is unique and practical so that resolves the runaway issue ( safety ) . Hand starting a pusher is much safer and hand cranking does give you some idea of the compression as discussed . I guess you have to live with the levels of simplicity you want . It breaks down into some basic issues .....
 If i hand start i have some control of who is close to the prop , i can see smoke or listen for some irregular noises
If the brakes are "dead" locked like Bill suggests then that resolves the runaway issue , makes hand propping less of an issue .
If the engine stops in flight i am unsure if it can be air started ? and leading on to that is the issue of fuel systems . I like the fuel system where the last available fuel is in the lower seat / tank so if you have fuel your engine should not stop . On long decents and only fuel in the seat/ sump tank is it possible to have too little fuel pressure ?
During hand propping is the fuel able to get to the engine when its on its nose ? Do you use or have a boost pump for the start sequence ?
I suppose the nosewheel is another item which has a higher chance of error . The nosewheel window goes some way to remind the pilot of its status . I guess you have to be careful with your checks but i understand the possibility of  human error. From what i can understand the mechanical nosewheel system is rugged provided the gearing is not actually used to hold the nosewheel but that it is capable of going fully over center for locking . The overcenter cam taking the landing loads .
What about fuel systems ? Do you place the filler caps so the aircraft can be on its nose during filling and still be filled to its max ? Some have a fuel drain close to the leading edge of the strake to check the fuel when the aircraft is in the nosedown position .
Flyoz