Sapphire Problems

[JohnMcK]

Hi All,

 

One of my constituents sent me this report about Sapphire Problems. He has previously sent it officially to the authority but feels not enough was done to inform other local owners of the problem. I personally can't comment on the technical side of his report, but I do feel there is merit in his report. Other Sapphire owners may have also have some interest in what he has to say. I have removed his name, but I could put other concerned owners in touch with him if they wish further clarification.

 

Forums like this are a good way to get out information quickly. However it must always be remembered that to do things properly an authority must examine all evidence, find out if there is a systemic problem, or only a once off isolated issue, and then make a judgement or decision. This takes time, and sometimes investigations can produce outcomes that are different to those originally thought.

 

Cheers,

 

John McK

 

Sapphire Problems

 

I have owned my Sapphire for two years. When I test flew the aircraft, I remember thinking that its sensitivity to the controls would probably be quite enjoyable when I got used to it. Coming from a GA/gliding background, and having received information from people I then regarded as informed, it had never occurred to me that there would exist a popular design like the Sapphire with an undocumented dynamic instability on one of its flight control axes. However, as it turns out, the Sapphire design is inherently unstable in pitch and requires either continuous hands-on control or a fully serviceable stabilator-centring system to maintain a constant attitude.

 

A notable difference between the Sapphire and most other small aircraft is that it does not use conventional stabilizer/elevator surfaces for pitch control. Sapphires are fitted with stabilators, a type of horizontal tail, the whole surface of which changes angle of attack in response to control inputs. Unlike conventional tails, which tend to dampen pitch change caused by turbulence, undampened stabilators can exacerbate pitch change. Firstly, they tend to align themselves with changes in airflow (weather-cocking) and, secondly, they respond inertially to vertical movements of the tail because their centres of gravity are behind their hinges.

 

Normally, stabilator-equipped aircraft have systems which provide a centering force on their stabilators. For instance, the Piper PA-28 series of aircraft has an anti-servo tab along the trailing edge of their stabilator. This tab moves in the same direction as the stabilator, increasing the centring moment in proportion to the deflection of the stabilator from its trimmed centre point. The other type of centring system that can be employed is a mechanical one working on the stabilator push rod.

 

The original Sapphire design had no such centering system, aerodynamic or mechanical. The only warning of the aircraft’s pitch instability was in the flight manual, which instructed pilots to always fly the aircraft hands-on (this is still the case, actually). However, in the 1990s, a stabilator-centering system was added by the then owner of the business, Don Bowd. This system is located under the pilot’s seat, a very inaccessible (and therefore difficult to inspect) position in the Sapphire. It employs shock cord (bungee strap) to provide centering forces to the stabilator via the push rod. The system is functional, though perhaps insubstantial, relying on the use of hose clips to secure the shock cord to the push rod.

 

After buying my plane in southern NSW, I flew it north to Brisbane and quite a bit of the flight was done hands-off, trying to fold maps, etc, without any unusual occurrence. I had been told about the system under the seat, but only in the context that it was a trimming system which had very little adjustment. I don’t believe the previous owner had any idea of the system’s critical importance to the safe operation of the aircraft. I suggest that this ignorance might be very common among Sapphire operators.

 

Last year, I discovered the consequences of a malfunction in this system. Basically, the detachment of the rear shock cord of this system caused a sudden change of pitch downwards in response to minor turbulence when the aircraft was being flown hands-off. The aircraft immediately went into a negative g condition causing disarray in the cockpit and requiring prompt hands-on recovery. Simply the array of objects that came loose in such a situation could have caused catastrophe. The cause of the problem was the rear shock cord had slid through the hose clip attachment point on the pushrod. I have since built a more substantial and accessible (easier to inspect), alternative system for centring my aircraft’s stabilator.

 

The existing system, if properly maintained and inspected, is a satisfactory one, however, Sapphire pilots must understand the system’s critical importance to the safe operation of their aeroplanes. It should be checked every six months or so, and only high quality aviation or marine grade shock cord should be used.

 

There would be Sapphires out there now with shock cord under their seats that is more than ten years old.

 

Sapphire Owner (name removed)

 

 

[Yenn]

This points up the fact that aircraft should have an annual or 100 hourly inspection, whichever comes first and checking of the trim system should be done then. I would also expect to see mention of the checking required on the paperwork with the plane.

 

 

[winton]

maybe unbeknown to you. There is nothing wrong with the handling of the sapphire. that was the way it was designed.

 

The problem is people ask there aircraft to do things that they are not ment for. the sapphire is for flying. I have flown

 

maybe 15 Sapphires ( all new, test flys )plus my 95 - 100025 117kg 377 Sapphire. have you ever scrapped your fuse on the ground, no! and that would be because of the full flying tail. the handling of the Sapphire , In my opinion is second to nun. I have flown a variety of ultralight

 

as well and nothing has come close. If you have a problem with the handling of a Sapphire its proberly because of the weight you are carrying

 

and your CofG is out. To fly a Sapphire hands off 4 things have to come together? try flying a bit faster in a drifter and let go the stick.

 

Sorry! some one has to stick up for it. dean has been I love my Sapphire. and i cant wait to fly my Facet Opal,

 

 

[Garry Morgan]

I have used all flying tails for a very long time on many aircraft, the saphire has the tail spar pivot a little to far back, if it was foward a little it would be more stable the bungge trim is a good idea to inprove this , they are a light aircraft and you would expect it to be light on the controls, they are still one of the best single seat aircraft around after more than 20 years, good on you Scott.

 

 

[facthunter]

I'm not a total fan of flying tails (Neither is Bill Whitney who knows more about designing aircraft than I ever will). They have to be designed right. Lots of Pipers use them and you have to keep an eye on them structurally. They are a more critical component that a conventional horizontal stabiliser and elevator combo. The pivot point is critical. Too far back and it is unstable. The CT has it and has had flutter related failures in an OVERSPEED situation that you really can't blame the plane for. The feature is popular because it IS a more effective control with less drag. The Saphire is an "inspired" little plane with many adherents. ALL planes should be regularly inpected. The way to do this is best handled by having a site where all the information about that particular aircrafts "quirks" can be listed. ONE MAKE associations make the flying of their aircraft safe through time, in fact they could be much safer than when they were new because of the accumulated knowledge. Nev

 

 

[nong]

As with many of our machines, Sapphires are not certified (and are not required to be) to a standard that spells out pitch stability characteristics in any detail. I think this is often not understood by many of us....

 

If curious, look up the certification requirements in relation to the tail number. EG. 10-xx 19-xxxx 25-xx

 

Popularity is not a basis to assume that a machine will have certain characteristics that might be desirable. It just ain't that easy...sorry! The Sapphire is a "real ultralight" as the term was once understood. Cheap and cheerful was the aim. With this as an overriding priority, it stands to reason that the machines must have been developed on a tight budget. When you buy a sapphire you don't pay for a lot of development and you dont receive it. What you do get is "bang for the buck".

 

Yes, Sapphires can be mildly pitch divergent when loaded within the approved C of G range. This might be a hanging offence in a touring aircraft selling for 150k, but for a cheap buzzabout.....just hold the stick.

 

I have an old Yeoman agricultural aircraft (certified to a more demanding standard). For what it's worth discussionwise, the maintenance notes emphasise the importance of ensuring that the fore/aft balance point of the entire 'stabilator' assembly coincides with the pivot point. The assembly includes a heavy balance/dampening weight mounted on an arm extending towards the front of the machine from the pivot point.

 

The stabilator was developed by Miles Aircraft as a fix for pitch control difficulties being encountered at transonic speeds with the M52 project. It was quite successful and widely adopted on jet fighters. Unfortunately some light aircraft designers thought it would be trendy and modern to use stabilators. It was a fashion statement in the fifties and sixties but is difficult to justify in most light aircraft applications in comparison to a conventional set-up.

 

 

[Student Pilot]

I have an old Yeoman agricultural aircraft.

Cropmaster? Yoo goanna put some piccies up? 470 Continental version?

 

 

[winton]

I'm not a total fan of flying tails (Neither is Bill Whitney who knows more about designing aircraft than I ever will). They have to be designed right. Lots of Pipers use them and you have to keep an eye on them structurally. They are a more critical component that a conventional horizontal stabiliser and elevator combo. The pivot point is critical. Too far back and it is unstable. The CT has it and has had flutter related failures in an OVERSPEED situation that you really can't blame the plane for. The feature is popular because it IS a more effective control with less drag. The Saphire is an "inspired" little plane with many adherents. ALL planes should be regularly inpected. The way to do this is best handled by having a site where all the information about that particular aircrafts "quirks" can be listed. ONE MAKE associations make the flying of their aircraft safe through time, in fact they could be much safer than when they were new because of the accumulated knowledge. Nev

aircraft designer, have a look at the sentinel and then tell me who you think designed it????????

 

 

[fly_tornado]

Tornados have stabilators and they don't have stability issues, Tornados are using Jabiru 3300 engines so you think they would have problems with all that power and 150MPH VNE.

 

 

[nong]

Cropmaster? Yoo goanna put some piccies up? 470 Continental version?

This one has the 0-540. It is undergoing a far too slow overhaul/rebuild and I don't deserve to post pix until it's together! Could post a 'BEFORE' shot if I knew how to attach. The fellas at Yeoman were fair dinkum aussie and kiwi battlers......colourful history! Oh yeah, and some of the operators were rogues! The old man had one and it was heaps of fun to ride in the loaders seat behind the hopper. He had already written off two Wacketts so we expected that he would kill himself in it. Sold it instead. Not very like a Sapphire!

 

 

[winton]

hi

 

Just a bit of trivia about the Sapphire. Every Sapphire was made to FARs 23 standard. At the time Aust had no standard to go off.

 

Made with a safety factor of two, 8gs positive 4gs negitive. Just stay under 100kts! OH, And thats a problem I have when I here someone has a 503 in there Sapphire! How fast, I wounder? I know the terminel verlosity of a Sapphire, it was done once. He all so put 4 pound of lead in the tail boom (no motor) and rolled off Stanwal tops, got a slap on the wrist for not have a hangliding ticket. Scotts view on the elervator was it had to have some stick pressure. If he moved the pivet point fwd it would trim well, yes. but what would happen now is the lightness on the stick would allow for sudden piching up or down,(at speed) where before, the stick fell fwd.

 

All aircraft are a compromize. All aircraft have a job to do. All aircraft do there job well. All aircraft sould be flown within there envolope. dean has been

 

 

[Guernsey]

Hi Nong reference your " Could post a 'BEFORE' shot if I knew how to attach. Contact IAN our site developer and he will gladly tell you how. Alan.

 

 

[pylon500]

Interesting that someone would discuss with owners, read the pilot handbook, be aware of the aircraft's habits, then buy one and complain about it.

 

Anyway, of the six Sapphires I've flown, I've always known of this handling characteristic and flown accordingly.

 

There have been a few Sapphires modified by adding an anti-servo tab system to them.

 

Not a problem on a 10 or 19, I just guess owners of 25's have to decide for themselves. :csm:

 

Should be interesting to see another Opal flying again.

 

ps; Titan Tornados have an anti-servo tab system.

 

 

[Guest Mark Mac]

...and i cant wait to fly my Facet Opal,

Hi winton, are you 'the' Winton?

 

If not, perhaps this link can provide you with some pre-flying considerations for the Facet Opal. http://www.atsb.gov.au/publications/investigation_reports/1989/aair/aair198902600.aspx

 

 

[Guest Mark Mac]

Hi David,

 

Thank you for so politely making me aware of the history and your and Deans part in it. I am unreservedly unapologetic for any bad memories it may have brought back.

 

My interest in the Facet Opal stems from my son outlining an almost exact design as part of his Flight design course at College. We are currently building a STOL (Ragwing RW20) so it is currently at the other end of the scale for us.

 

Regards,

 

Mark

 

 

[Guest Mark Mac]

From Plans, although I did acquire the semi completed project from a gentlemen in Bendigo who had already done the wings and the tailfeathers, I am about 50% through the fuselage

 

 

[winton]

thank you for the link to Scotts report. Its been a while since I last read it. I went through the procces to have it change to the truth but at the last meeting with BASI, The boss got stuck in melborne with the first fuel strike, and never made it. So Scotts report was never changed. They did not take into account the hole in the spar and the way it affected the strength of the airframe. I saw the damage and studied it, used a bit of common sence. When Scott turned left (So he did not fly over the road or did he think, Ill land at doylo) his wings loaded up and the sheer web bulged out and tore bringing the spars together but now the control system takes over and makes the wings go down. ****! poor Scott. It was easy for them to put the blame on Scotts piloting skills and his aircraft, there was no third party involved so that will do. thats how I read it then. I dont think any one has any idea how stable the Opal is, taking the human element away and flying it with a fly by wire will get it back to how it was designed to be. Flat and fast. Thats up to me now. I have not done any work on the Facet Opal for two month now and it will another two before I can get back to it . I did do 100 days staight and a 1000 hours of work on it. If you want to push me off a hill, its ready to go. A paint job would be good. DHB

 

 

[Guest Marshy]

Hello All

 

Was after some info on the Sapphire, if you'll have the time type.

 

I'm looking a the sapphire aircraft as my first aircraft. Have looked at the info avaliable and was impressed.

 

But there is one thing, SIZE not so much the aircraft but my size as I'm 6' 2" and will be around 100 to 105kg flying.

 

So is there any taller sapphire owners out their? and if so how do you find the fit?

 

I'm trying to find on in WA as so I can go have a look and a fit up, but as of yet haven't found one.

 

I fly gliders as well (as you can see via my photo) and this is why the little machine struck a chord.

 

So any info would help.

 

Cheers Marshy

 

 

[winton]

Hello AllWas after some info on the Sapphire, if you'll have the time type.

 

I'm looking a the sapphire aircraft as my first aircraft. Have looked at the info avaliable and was impressed.

 

But there is one thing, SIZE not so much the aircraft but my size as I'm 6' 2" and will be around 100 to 105kg flying.

 

So is there any taller sapphire owners out their? and if so how do you find the fit?

 

I'm trying to find on in WA as so I can go have a look and a fit up, but as of yet haven't found one.

 

I fly gliders as well (as you can see via my photo) and this is why the little machine struck a chord.

 

So any info would help.

 

Cheers Marshy

[Riley]

Marshy

 

Give 'Glen' a call on 0438 958 020. I'm sure he'd be happy for you to plunk your bum in his Sapphire at Bindoon some weekend. If any contact problems, get back to me & I'll get him sorted. cheers

 

 

[Guest Marshy]

Hey Riley

 

Cheers for the number got hold of Glen tonight, will have a gander at his one one the weekend:clap2:.

 

hears hopen I fit (like a glove). and that the one I had my eye on hasn't been sold:beg:.

 

Cheers Marshy

 

 

[rick-p]

Hi Winton,

 

Totally off topic but are you Dean or his son?

 

Maybe I missed something in the previous posts it's just been a dam long day.

 

Thirty or so years ago did you fly RC up on the Central Coast, near Gossford?

 

I recall one of the Winton boy's who were members of the club turning up with, if I remeber correctly a model of the Opal Facet.

 

They were great times, good people and great model flying.

 

Rick-p

 

 

[winsor68]

I swear I saw adverts for a kit for the RC Opel years back in aeromodelling mags.... ?

 

 

[rick-p]

Well Dean maybe would then remember John Timmins and many other RC flyers from the central coast club. Probably wouldn't remember me but I do remember the day that he brought, I think, the proto type to the club and there was talk about aeroflyte or one of those model manufacturers taking it on. Dean was and probably still is a very proficient RC flyer. I was pretty hopeless my models all seem to crash on the main road that went past the flying field.