Mudgee

[turboplanner]

Thanks, I was thinking OK could make up a small panel based on current construction, test it for rigidity, then bond the frame and skins together and see what the increase in structure is.

 

 

[Yenn]

Bonding / glueing to aluminium is a bit difficult and although it has been done succesfully it is not easy in a homebuild situation. The outer surface of aluminium oxidises very rapidly and that is what protects the aluminium from corrosion, but the oxide layer causes problems with glueing. I have done it by abrading the surface with wet or dry paper coated in the glue and then rapidly completed the joint. What i did was not a structural part and it held together as long as I needed it, not sure what it's real life would have been. There are glues specialy designed for aluminium, but they need care in use.

 

 

[Dafydd Llewellyn]

If we're talking about the Jodel, I'd stick with wood; that avoids thermal and moisture - induced stresses due to mixed materials. Wood has an ability that metal and plastic materials lack, which is the ability to withstand a much higher short-term load, than a sustained load. That provides a substantail "hidden safety factor" . But how do you escape from the aircraft in the event of an overturn? If it's by breaking out through the cockpit side, then reinforcing the skin may not be the right answer.

 

Canopy-type aircraft generally present two problems; firstly the weakness that is unavoidable when you have a hole in the wall of an essentially tubular structure, for people to sit in; and secondly, in the difficulty of emergency escape in the event of an overturn. You may note that Rod Stiff has repeatedly resisted all efforts to persuade him to produce a low-wing aircraft; these are some of the reasons.

 

In the case of an aircraft like the RV, turning the cockpit side panel into a sandwich panel does not answer the principal issue, which is that the cross-section of the cockpit sill needs to be resistant to both buckling about its axis of least inertia, and to torsional buckling. That really calls for a closed box or tube for the sill member. The RV3 and 6 have a piece of extruded aluminium angle, and the mode of failure is that it first twists until the restraint of the skin no longer stabilizes it about its axis of least inertia, and then it fails by lateral crippling. As a result, its compression load capability is surprisingly low. I don't know to what extent that is a common design in similar aircraft - but putting a box section there instead of the angle is not the sort of thing of which most builders would understand the significance.

 

 

[M61A1]

Bonding / glueing to aluminium is a bit difficult and although it has been done succesfully it is not easy in a homebuild situation. The outer surface of aluminium oxidises very rapidly and that is what protects the aluminium from corrosion, but the oxide layer causes problems with glueing. I have done it by abrading the surface with wet or dry paper coated in the glue and then rapidly completed the joint. What i did was not a structural part and it held together as long as I needed it, not sure what it's real life would have been. There are glues specialy designed for aluminium, but they need care in use.

With a little care, it's not too difficult, ideally the surface should be grit blasted, and conversion treated (alodine or other), dried at a temperature between 60-120 deg C, and bonded with scrim cloth in the joint to ensure that adhesive remains in the joint and not squeezed out. As with all good adhesives, accurate mixing is essential.

 

 

[Old Koreelah]

Thanks, I was thinking OK could make up a small panel based on current construction, test it for rigidity, then bond the frame and skins together and see what the increase in structure is.

Sorry Turbs, been travelling. My Jodel, as M61A1 says, has an outer skin of plywood. Some builders sheet theirs in fine fibreglass for strength- a job I may do in the near future. I have used quite a lot of Klegecell (rigid PVC foam) between sheets of 1.6mm hoop pine ply. Rigidity is not always the ideal; the ability to flex without fatigue is one advantage of pure wood. I did make and test a whole lot of composite panels when building a previous aircraft, but didn't when modifying the wooden Jodel.

 

 

[Keenaviator]

I think if you are unfortunate enough to end up in a high sink rate close to the ground (as can fairly easily attained in a low aspect aircraft), the high 'G's your body may be subject to may not be survivable. The springy RV tubular undercarriage may not be able to absorb the downward energy and the couple of centimetres between the bottom skin of the fuselage and the seat pan doesn't provide much distance to absorb energy through crushing. With this accident there are many variables and possibilities leading to the loss of control. If I were conducting the investigation I would be very keen to get the post mortem results. Laurie

 

 

[turboplanner]

I think you're right Laurie, depending on that the structure of the aircraft may have made no difference at all if the injuries to the pilot were G force related, or may have played no part at all if not. We only have a few similar photos of the upper part of the aircraft.

 

 

[Keenaviator]

I know the aircraft well. The stripe/join in the white and blue along the side of the fuselage is meant to be straight and it appears to sag in front of the firewall. Also it appears to be very flat on the ground and the wing appears to have less dihedral than it normally would have - all signs of a relatively high 'G' pancake onto the ground. Laurie

 

 

[ave8rr]

Rv6's and 7's are fantastic little aeroplanes. And with the RPL now, a very viable option for some of us. The thing to consider is that they are NOT light and fluffy designs. They are designed for speed and manoeuvrability, to give the classic RV grin! They will bite harder then a sportstar or a Jabiru if flown "off spec".The last one I flew cruised ver comfortably at 165 IAS and was certainly a "lively" feeling aeroplane.

The RV9/A cruises 160+ kts and is still flying at 40 kts. The RV9/A wing is longer and narrower than the 6/7 models and has a greater tail plane span giving plenty of elevator authority even at very low speeds. The aircraft is NON aerobatic.

 

 

[winsor68]

I think you are referring to the cockpit sill reinforcement kits that were being produced by Graham Moodie (I hope I have that right) after he saw parts of a report that my son wrote to the QLD branch of ATSB, after he and I examined a wreck of an RV3 and an RV6 (both fatal) at Toowoomba, with ATSB's permission, at least a decade ago. (We were looking for data relating to lower leg injury, in a quite different context, but the fuselage collapse mode was something we noticed in the process). I could not approve an EO under CAR 35 because the aircraft is experimental, and therefore does not comply with any normal design standard - so the wording of CAR 35(2) is impossible to meet; however I saw what Graham was doing, and it looked to me to be helpful. Both those aircraft folded as you describe due to outward buckling of the cockpit sill, which completely nullifies the effect of the safety harness; the turtle deck behind the cockpit had paint marking from the windscreen arch in both of them; the fuselage had acted as a giant nut-cracker in fact.I would be interested to know whether the Mudgee aircraft had this mod. installed. However the presence or otherwise of the reinforcement has no bearing on the cause of the accident.

Thanks David. At least something positive may have come out of Uncle DBs death.

 

 

[Dafydd Llewellyn]

You're most welcome; however it's a legal obligation for a CAR 35 engineer to bring things like that to the attention of the relevant authority. Preventable, unnecessary death and injury is anathema to me.

 

 

[winsor68]

Sadly I still have a brother who blames engine failure. Can tell him 50 times that engine failures don't cause aeroplane crashes to no avail.

 

I am also comforted by recent safety discussions regarding partial engine failures.

 

 

[Teckair]

This is why practicing glide approaches is a good idea but there are so many who do not do it.

 

 

[Dafydd Llewellyn]

I agree; but it won't help if the engine dies at 50 feet and you have to get across a six-lane road and a ten foot high cyclone wire fence, to reach the school playing field on the other side. That's what caught the RV 3 pilot.

 

 

[alf jessup]

This is why practicing glide approaches is a good idea but there are so many who do not do it.

Teckair,

 

Not a truer word has been spoken mate, I cannot imagine how many fellow aviators don't practice emergency procedures in between the BFR's.

 

I myself practice stalls, steep turns, simulated forced landings and plenty of glide approaches on a more than regular basis.

 

One of my favourites is to be snoozing along in circuit and chopping the power part way along downwind, converting my speed to height while turning in towards the runway and setting up a forced landing, a lot of time I do flapless landings in general just in case the electric flaps decide to give up the ghost one day.

 

Every now and then I pull the power on climb out just for the hell of it and set up.

 

I don't always do these procedures on my home strip, occasionally I do a few at different local airports.

 

A lot of it has to do with your attitude towards aviation in general, me I have a healthy respect for it as I know it bites hard and is unforgiving if you mess up.

 

Alf

 

 

[Teckair]

The best way is to aim to be slightly high at the thresh hold and when you are sure you will make it loose the excess height with flap or side slip.

 

 

[Teckair]

A lot of it has to do with your attitude towards aviation in general, me I have a healthy respect for it as I know it bites hard and is unforgiving if you mess up.

Alf

So true.

 

 

[alf jessup]

I was trained that it is better to hit the far fence at 10 to 20kts than the near fence at 60+ & I stick to that theory

 

 

[turboplanner]

It's also better to hit the roughest ground above stall speed than fall out of the sky, and that means making an early decision that the primary aim when the engine quits is saving your body, not the AC.

 

Richard, I agree with practicing glide approaches and I wouldn't suggest cutting back, but a lot of RA fatals have been engine failure followed by falling out of the sky from over 1000 feet,so most of my practice is ingraining and instant subconscious action to trim for glide before anything else. Once you are gliding you have time to assess and plan.

 

Alf, a secondary to your far fence system, if making the boundary fence/landing past the drainage distance is doubtful is to go early and hit the boundary fence when you're on the ground rather than trip over it with the undercarriage.

 

 

[dutchroll]

I don't personally know of too many guys who regularly practice glide approaches in a Pitts, because where you can land is generally determined by what is immediately beneath you! If you don't have a field somewhere below you, then you have problems. At 3000'/min descent rate if the prop isn't coarsened off, you have as little as 20 seconds to touchdown from circuit altitude, and that's if you don't turn! You cannot make it back to the runway from anywhere on a "normal" GA downwind spacing.

 

 

[alf jessup]

It's also better to hit the roughest ground above stall speed than fall out of the sky, and that means making an early decision that the primary aim when the engine quits is saving your body, not the AC.

Alf, a secondary to your far fence system, if making the boundary fence/landing past the drainage distance is doubtful is to go early and hit the boundary fence when you're on the ground rather than trip over it with the undercarriage.

Turb's,

 

Agree totally on all points above, hopefully we make a good decision early and pick the paddock without the drainage ditch but if that is the only option agree dissipate energy on the ground and hopefully steer between those darn 4"posts and lose some more energy without trying to decapitate yourself with the wire between the posts.

 

Fly as far into the crash as you can while you have control, once control is lost or if control is lost at altitude to low to recover your a passenger like the person sitting beside you if your unfortunate to have one in with you and your outcome is probably not going to be a good one.

 

I love my plane but that's why I have insurance I can replace it so is comes a very distant second to me surviving.

 

Alf

 

 

[djpacro]

I don't personally know of too many guys who regularly practice glide approaches in a Pitts ... You cannot make it back to the runway from anywhere on a "normal" GA downwind spacing.

On downwind with the wingtip on the piano keys, close the throttle and turn will attain the runway.

[Teckair]

Yes there are some aircraft that don't glide so well I am talking about types that do, but even in a Pitts if you don't have a plan for when the engine stops you are living dangerously.

 

 

[Keenaviator]

All these tips are great IF you have the capacity to perform them. I would suggest that someone with Terry's experience would already know and practice these valuable practices. Was he well enough to carry them out? Was he conscious? Who was flying the plane at the time? I believe there was a go around prior to the last attempt. Lots of questions. Let's wait for some answers. Laurie.

 

 

[alf jessup]

All these tips are great IF you have the capacity to perform them. I would suggest that someone with Terry's experience would already know and practice these valuable practices. Was he well enough to carry them out? Was he conscious? Who was flying the plane at the time? I believe there was a go around prior to the last attempt. Lots of questions. Let's wait for some answers. Laurie.

Laurie,

 

We are no way doubting Terry's flying ability in any way shape or form, I am sure Terry was well versed and a very competent flyer.

 

I am with you in the feeling that he somehow became incapacitated prior to the accident.

 

Alf