Flying a Zenith 601xl [comments]

[Thruster87]

From: Doug - SportAviation: I have some experience teaching people to fly the Zodiac as I’m a CFI and used my Zodiac for a while as a teaching platform. A repeatable characteristic among those who fly high(er)-wing-loaded aircraft and are transitioning to the Zodie is their heavy-handedness on the controls. This generalizes from private pilots to ATPs. In fact, there were two other CFIs I couldn’t sign-off to fly the Zodiac because they couldn’t land it – an almost unbreakable PIO near the ground for both. They were the instructors who spent most of their time in twins. It’s clear (to me) there is a certain kinesthetic sense required to fly the Zodiac which is conflict with those built up in other GA airplanes. This seems to be borne out from the insurance stats. One-finger control to press on the stick to change attitude followed by trim is the drill I would often use.

 

Another “quirk” of the Zodiac is the location/height of the gear (I’m referring to a 2007 AMD airplane) and the angle of incidence of the wing (lower angle of incidence, not like the 650 is now or the 601 was earlier). This combination requires a deliberate rotating of the airplane for takeoff. Without the rotation the airplane will just continue down the runway never taking off. Given the weight distribution wrt the gear location, the deliberate action required to rotate is too much stick for maintaining the nose angle one wants for climbout. Thus, it almost immediately results in a nose-too-high attitude once the airplane leaves the ground.

 

The challenge is ensuring folks don’t panic at this point and shove the nose down (gotta ensure you box the stick with your hands!). That can result in a “good belt workout” at a critical altitude. If one takes off at 60 knots, there’s enough kinetic energy in the airplane for a nice easy correction.

 

Or, the stick was used to remove the wings. As I have related previously, I was letting a passenger, who was a Piper Tomahawk owner, fly. It was a gusty day and on climb out at about 80 - 90 kts, the nose pitched up. He slammed the stick forward to lower the nose and gave the seat belts a good workout. He did not go too far forward with the stick as I blocked the stick with my hand; however I have no doubt, he would have put us through the canopy if not for the belts.

 

(I still can not believe an experienced pilot would have done something like that!)

 

I think it is interesting that you choose to use the term "pilot/builder". In fact, the only thing common among all the XL crashes is that NONE of the involved pilots were the builders of the airplane that crashed.

 

I am assuming that the latest crash you refer to is the one in Utah. It is STRICTLY a personal opinion, but I believe the same thing happened to that unfortunate pilot as the phenomena that ended Steve Fossett's storied life - inadvertent entry into a mountain down draft that the pilot and his airplane simply could not overcome.

 

 

[Guest Qwerty]

T87

 

I have flown several hours in a mates 601 XL. It is a sweet a/c and I enjoy flying it, I would have only one reservation about buying one if my needs matched its capabilities. The reservation BTW is re rollover/exit difficulty. The handleing is fine. As you mention there are a couple of quirks but then most a/c have a quirk or two and those that don't are generally labled as docile or boring. I did however think that the difference in response between roll and pitch was large and it took me some time to get used to it. I couldnt help thinking that a stab/elevator would give better results than the flying tailplane. The other thing that is a bit irritating is the weave. I am stuffed if I can work out what the cause is. Any thoughts?

 

Qwerty

 

 

[Thruster87]

T87I couldnt help thinking that a stab/elevator would give better results than the flying tailplane.

Qwerty

The 601xl has Stab /Elevator but a Flying Rudder [no vertical stab].It's always a bit of a problem [roll over safety] with most low wing bubble canopies.Best to have a emergency exit tool handy to shatter the canopy.

 

 

[Thx1137]

Best to have a emergency exit tool handy to shatter the canopy.

G'day, sorry this is off topic but what is recommended for doing this? On our buses they have a little hammer but I have heard about a mechanical punch that is supposed to work ok. I like the idea of the hammer because it has no moving parts but I have no idea how either of them work on bubble canopies. Opinions?

 

Steven.

 

 

[Guest Qwerty]

Of course the XL has a stab/elevator (I was thinking of another a/c which was damned near impossible to fly because of what is basically pitch instability). The XL does, however, seem to me to be too sensitive in pitch, particularly compared with its roll response.

 

I doubt that a hammer of any type would be reasonable solution to the roll over issue. The acrylic canopy will be damaged as a result of a roll over but the head room remaining will be an issue. I doubt that the conopy will disintergrate enough or disintergrate reliably enough to provide for escape. This all might just be my own phobias.

 

 

[Thruster87]

On mine there is roll over protection via headrests [old volvo] and beefed up rear bow [turtle deck].On the updated 601xl [650]it has roll over protection built into the design.I saw a neat little tool the other day that had the pointed steel end and a torch in the other end.Didn't ask where he got it.Any cracks formed via the tool or crash can be kicked out, which may give you a fighting chance to get out.The elevators were made large to give good slow speed control, it is always a compromise as to which design features you would like.Cheers

 

 

[Guest Qwerty]

I thought that a stronger bow would probably work. That pointed hammed sounds like a good idea...I'm not sure about the need to store flat battries in the handle though.

 

I am with you on the compromise re low speed authority vs. cruise speed twitchy but I thing that there is room to coordinate the responses in pitch and roll. It is still a very nice piece of work just the same.

 

 

[Guest Decca]

Qwerty can you expand on "the weave" please? (post 2).

 

Decca.

 

 

[vk3auu]

Elevator authority

 

Surely a lower "gearing" between the stick and the elevator would reduce the pitch sensitivity without reducing the effectiveness of the elevator at lower speeds.

 

On my old 701 I had to put vortex generators underneath to increase the effectiveness of the elevator at low speeds as even at maximum deflection, I couldn't get the nose up with full flap at 45 knots or lower.

 

David

 

 

[Guest Qwerty]

Sorry, yes,

 

Weave: defn,. Uncomanded ocillations in yaw, more pronounced in light turbulance and very irritating. not altogether uncommon in low wing aircraft.

 

Cheers, Qwerty

 

 

[Guest Decca]

I swear - the older I get the less I can remember. It sounds a bit like Dutch Roll. Is it ONLY apparent around the normal axis as yaw or is there also a rising/falling wing motion detectable (about the longitudinal axis), in rythm with the yaw?

 

How rapid are the cycles?

 

Has any other Zenith601 pilot experienced this please?

 

Regards, Decca.

 

 

[Guest Qwerty]

OK Decca, battle of the failing memories.

 

Its not a Dutch Roll, they are pretty much confined to high speed, high performance jet type a/c. I have seen it on many passenger jets. The auto pilot is prety well setup in those things but you can still see the wingtip doing a slow "backwards" rotation motion. It is more pronounced on some than on others. I think that the most obvious one was a fairly late model 747.

 

What I am refering to re the 601 is a cyclic yawing of about 3-5 deg with a period of about 1 sec (from poor memory). With the short wing span the secondary effect of roll doesnt seem to develop (and therefore not Dutch Roll). It is almost nonexistant in smooth air and gets worse with turbulance which makes me think that it may be related to alieron gap drag. It is difficult to detect in rougher turbulance...that is not to say that it is not there but that it is difficult to pick the weaving from the turbulance.

 

Is that a better explanation.

 

When I get a chance I will try to video it for you.

 

Cheers, Qwerty

 

 

[Guest Decca]

Thanks qwerty. I have experienced Dutch roll in 100 series B727s. Not an issue in the 200 series really due 20 foot longer fuselage.

 

Anyway don’t worry too much about taking this any further if it isn’t an issue for you or anyone else.

 

My suspicious mind was concerned about more sinister things having read about the mystery of why these things were going down & pretty much all fatal. And this is the first I had heard of “the weave”, which rang alarm bells, as I can’t recall it being an issue considered in the crash investigations.

 

Decca.

 

 

[chris]

QWERTY

 

"I have flown several hours in a mates 601 XL"?? considering there are so limited XL's flying, and non in TAS wehre is your mates Zodiac XL located?? or was it a standard 601?

 

Chris

 

 

[Guest Qwerty]

Well bugger me, there's my memory going again. I was sure that he said it was an XL, I just looked on the register and it is registered as an Hds. Sorry for leading you astray fellas. I will try harder....I promise.

 

BTW what differance does it make and what is the differance between the XL and the Hds?:thumb_up:

 

 

[chris]

The HDS has a much thicker wing and is joined out about 2 feet from the fueslage. the XL has it wing joints right at the fuse and the MLG is a flat bar system like a Cessna from the fuse not the wing like the HDS..

 

Chris..

 

Zodiac XL

 

Jab3300

 

 

[dougsmith]

Regards the earlier comment on over the rotating business happening on take off it can be somewhat disconcerting. When the our aircraft had reached flying speed it was necessary to pull it off the ground but very carefully to catch it so as not to go too nose up and stall. Similarly on landing and holding the nose wheel off the aircraft would reach a speed where the nose wheel would be suddenly thumped onto the ground. This appeared to be because the wing angle of incidence was sufficiently negative when all wheels were on the ground with the effect to hold the aircraft down in that "level" position when attempting a take off until the elevator had sufficient authority to overcome the down force of the wings. This condition was corrected by lengthening the nose wheel strut by 50 mm, even thought the strut had been made according to the plans. This has given the aircraft a small amount of positive wing incidence and a better looking stance, now it sits level and not nose down as before. It is now a pussy cat to fly, just a slight back pressure on the stick and it takes off pretty much when it is ready, usually around about 50 kts, and no longer leaps into the air. On landing the landing run is very controllable and the nose wheel sits down nicely after the normal hold off. In 4 years since the mod. the aircraft has performed beautifully which leads me to think that the design could be improved in respect to the wing incidence when at rest. I have not noticed any weaving mentioned above, in this particular aircraft, a 601 HD The ailerons are adjusted both slightly down so they are "pushing" against each other and so negating any ability to flutter.

 

 

[motzartmerv]

I don't know how old this thread is, but I have a question or 2.

 

As im test Flying t87's 601, can anyone with some serious time in the acft give me a bit of an idea about what its supposed to handle like?

 

I have done a few flights in it and so far it seems quite nice to fly. Very sensitive in pitch as others have said and quite heavy in roll.

 

I put it through some clean power off stalls last sortie. Any tips would be great.

 

Thanx

 

 

[techie49]

Allan Barton at Zenair Australia is the man to ask. He's got a 601XL(B) (i.e. fully modified as per FAA and UK mods). He's done thousands of K's around the country. I'd be interested too as I'm getting my engine on next week and hopefully will be flying around Christmas / NY.

 

Regards,

 

Paul

 

 

[Allan 601XL]

Flying 601 XLB

 

I don't know how old this thread is, but I have a question or 2.As im test Flying t87's 601, can anyone with some serious time in the acft give me a bit of an idea about what its supposed to handle like?

I have done a few flights in it and so far it seems quite nice to fly. Very sensitive in pitch as others have said and quite heavy in roll.

 

I put it through some clean power off stalls last sortie. Any tips would be great.

 

Thanx

Send me an email [email protected] and we can have a chat

 

Cheers

 

Allan