skippydiesel

Yes Sonex have a test flight regime - very much focused on FAA modeling - I am slowly working through the RAA Flight Test, which may also  have its origins in the FAA.

I hope not to kill myself - hence the questions about the implication of any changes I might be contemplating.

At this early stage stalls are benign, without any tendency to wing drop.

Stall, without flap, is 40 knots, right on Sonex specifications. Stalls, with flap, are 37 knots (all stages) a bit higher than specification of 35 knots.

More complex stalls, at different weights & power, have yet to be conducted.

TO is exhilarating, climb out 1000ft/min @ 80 knots, landings messy (still lerning) as significantly higher approach speeds than Zephyr.

Multiple incremental adjustments to flight surfaces,  have resulted in a level cruise with the "ball" in the centre (no yaw). A shallow turn, without rudder input, will see the ball remain centered.

Also -I have not yet settled on flap/aileron/elevator setting - so stalls will have to be repeated for all adjustments,  which may result in some changes in above findings.

On the ailerons- the flaps have been adjusted to effectively counter a heavy forward stick (nose down). The aileron's are now trailing lower than the flaps. My thinking - this must appose (to some degree) the  effect of the flap adjustment. I may get more improvement, if I adjust the ailerons (by equal amounts) to the flap. With luck this improvement may be most pronounced at high speed cruise (where the excessive aft trim is currently needed). That is if I don't kill myself in the process.😆

2 hours ago, Thruster88 said:

Reflexing the ailerons up should have minimal effect on the differential ratio. Any change in the differential ratio will depend on where the ratio is produced, at the bell crank or at the aileron connection. 

 

If the aileron pushrod connection and the aileron pivot are at 90° to the cord in the neutral position then no change to ratio.

 

One advantage of reflexing ailerons up and maybe even reducing flap up reflex could be better stall behaviour. By reflexing only flaps up you are effectively reducing the wing wash out.

 

I would seek the advice of the manufacturer.  

Thanks Thruster88

I have tried getting help from Sonex (not on this topic) and found that when your project strays from the catechism, they get a bit evasive.

I have very limited exposure to aircraft  kit suppliers but within this, have found the Europeans flexible and the Americans rigid - litigation concerns??

Yeah! go for the expensive one, you may live to regret it.

I believe that;

Much like oil sampling , this is  RELATIVITY test - for most meaningful results, should be conducted over the engines service life,  so that results from, near new/ low engine hrs,  testing can be compared/ relate to the testing of the same older/ high hrs, engine. 

The type of devise is not as important as consistency of measurement . If you are a home mechanic, servicing one aircraft, purchasing an expensive tool is hard to justify, when a cheaper one will probably serve your purpose.

One off tests/results will give you low quality information.

Where have all the want to be aeronautical advisors gone, long time turning??

Surely some of my friends would like to munch on this little problem.

I invite constructive comments on the following;

My Sonex is in its early test flying phase. 

• Flights are conducted with one 70Kg pilot, nil baggage  and up to full fuel in wing tanks (2 x 30L almost on the C of G) Note: the centre, in fuselage, over pilots legs, 40L tank, is empty at this stage.
• Flight surface tuning (trim?) for level flight is well under way.  An erly tendency towards heavy nose ,or if you would prefer, the need for excessive back stick, has been addressed, in part, by reflexing the flaps up and by adding a heavier, pilot adjustable, aft trim spring. 
• The elevator is slightly raised - about 10-20 mm, at all times in cruise (I need to take more measurements to be precise).
• The ailerons (adjusted to the best "book"  compromise), are about 10-15mm (trailing edge) below the flaps. 
• This strategy has worked well for air speeds between 100 & 120+knots.

With higher air speeds, I run out of aft trim adjustment at about 135 knots.  This would be okay if centre tank was full ie as fuel burns off so trim could be adjusted forward.

I feel the trim spring solution is pretty much done.

I could add a small fixed trim tab to the elevator trailing edge, to lighten stick forces but would rather avoided this course solution if I can.

My preferred option is: Aileron Adjustment

Small change of flight surface alignment with/to the induced wind, usually have significant impacts on flight characteristics. If I adjust my ailerons to match the flap settings, this may further lighten the "weight" on the aft stick  BUT likely change the UP: DOWN ratio of the aileron movement  - what might the changes to flight characteristics be?

Any other thoughts?

Gut feeling (2 scientific methods in one) - could just be random and may not happen again - see how you go (another leap of non logic) AND what rating is the circuit breaker? could be tat its been operating near its rated limit all these years and a slight increase in current draw has put it over the limit.

Cant say I use official way points, unless I am required to be at a certain point in space, to enter say a lane of entry or controlled airspace. Is this a deficiency in my piloting/training?

I doubt there is much training involved in becoming a battery replacement technician.

My PLB was 10 -12 years old & still testing okay. I looked at the batteries - I recon I could have replaced them BUT I was told the unit could not be reinitialised/fired up without the proprietary gizmos.

The cost of the service plus freight was nor far short of a new more modern replacement - hardly a coincidence!

I bought a new one & sent the old back to the manufacturer for disposal.

10 hours ago, RFguy said:

Skippy see if it occurs with a low vapour pressure fuel such as AVGAS LL100. Put some additive in it (Decalin runup) if concerned about buildup just for one tank of fuel.

Thanks RFguy

Is this with reference to Nev's possible fuel bubbles/boiling?

I see the logic  - floats may perform better thereby more reliably keeping fuel level below "spill" height - no fuel in catch cans.

 As I have no intention of using AvGas (except when ULP 95-98 unavailable) I think I would rather go:

• Monitor under cowl temperature - have the system in place.  Up to now has just been for the occasional look/check - will take a more systematic approach over the next few flights. Findings may guide next step(s)
• Check/adjust clearance of brass armature/float bracket (float acts on, to open close inlet valve/needle) - should be 0.5mm ("Spacing on the 912 Series: 0.4 to 0.5 mm").  Possible manufacturing assembly error.
• Check float needle valve condition at the same time as above

1 hour ago, Blueadventures said:

If you reread my reply it happened on a new engine <14 hours.

Sorry I missed the 14 hrs - that's terrible! - Hope you got the fix under warranty.

Unless your "seats" were somehow miss aligned, I would have thought a polish/HD clean would have been sufficient - Wal's the man (in Au) so his word is law.

1 hour ago, Blueadventures said:

What is the link to polishing.  If I had the issue confirmed I will replace the seats.  Wal does the change out; Rotax say replace the carb body, expensive.  I’ll buy replacement seats and pull old and insert new.

Polishing the float bowl valve seat, is mentioned quit often in the Rotax Owners Forum (I have no personal experience). In any case, I would hope replacement/polishing not needed in a new engine.

Dwelling on Nevs suggestion (bubbles/boiling fuel) - next flight, will try to remember to record under cowl temperatures at variose stages. Could be instructive.

1 hour ago, spacesailor said:

An Odd thought !.

Is the carby vent on the down-side of bowl when climbing.

And can that part be rotated to the up-side.

spacesailor

Fairly sure that the vent spigot/nipple is about 1/2 way on one side. The attached short breather pipe is supposed to open to the same air pressure, being experienced by the carburettor inlet. In my case the the breather is connected to a spigot on the side of the air box, that the carby is attached too (in theory, same air pressure inside)

45 minutes ago, Blueadventures said:

Can get leakage at the float valve seat if corrosion is present.  Not seen with naked eye. Wal can replace the seats and first check for corrosion under a microscope.  Had it happen a year and half ago to an 14 hour engine that had sat around before first start.  Consider phoning and sending to Wal.

I understand that the seats can also be polished - presumably to remove surface corrosion or fuel varnish.

You beet me to my correction - I much prefer Badgerys Creek to Western Sydney International (Nancy-Bird Walton) Airport  - Two Sydney's in close proximity must be a recept for incidents to occur and Nancy-Bird Walton just doesnt have a nice "ring" to it.

17 minutes ago, Carbon Canary said:

Badgery’s Creek will operate 24/7.

For how long??? 😁

2 hours ago, kgwilson said:

The recommended callsign for recreational aircraft is R followed by the 4 digit aircraft registration number........................

I have always used the aircraft type followed by the 4 digits ie Zephyr 3360 - was never corrected.

Recently had an interesting call sign situation - called "Sonex 2041"............. (individual numbers) Tower "Sonex 20 41"............ (paired numbers) got told off by tower when responded ....................."Sonex 2041"

Turns out;

• If ATC use/respond in paired numbers, pilot must respond in kind
• Nothing wrong with individual numbers , that is until changed by ATC

This level of pedantry, is how inexperienced pilots get flustered and then go on to make mistakes

4 hours ago, onetrack said:

Because the hourly operating cost of the B747, with 4 engines, is much higher than a 2 engine jet, such as a B777 - with no major gain in payload for the B747.

4 engine jets are a liability in commercial operations today, since the reliability of todays jet engines is such that major trans-ocean flights can be done with ease with 2 engine jets, with no fear of crashing, even if 1 engine fails halfway through the flight.

Re powered with the latest engines or even modifying to 2 large engines, would not this aircraft be competitive?

10 minutes ago, facthunter said:

Why do you ignore the point I just made? It's happened on some cars requiring carburetter modification so why could you think it can't

happen with the Bing.  Nev

Is this for me Nev?

I didn't  ignore it - I don't have much to say - I take your point about bubbles/boiling fuel - other than redesigning the cowling (better air flow) I cant think of any easy way test for/ address this. I can see how it might happen and that it may occur during a particular (short) stage of flight (climb?) thus only producing a small fuel discharge (which is what I have). The new/lighter floats may also help in this situation, although the difference in weight between old/new would suggest marginally at best.

I should say my engine (Rotax 912ULS) is performing as expected - no odd behaviour. Fuel consumption is astonishingly low (10L/hr need more data) for indicated  performance  - last flight (from memory) 130 knots indicated (133 true) @ 4500 ft, 5200RPM/125MAP

After test flying completed, I intend to take the aircraft home for modifications to coolant & oil radiator location, which will also change the cowling (may be wholly replaced). This may also improve under cowl temperatures (better air flow) so by happy coincidence may also address your point.

All the best - always wondered why we don't produce such advanced sport aircraft in Australia.

You may like to check out the ATEC 321 Faeta (an aircraft with an extraordinarily wide flight envelope) for a few design pointers and performance goal setting

https://www.atecaircraft.eu/en

https://www.atecplanes.com.au/

There are two variants -. NG (looks much like your concept) and standard, which has a T tail (my preferred option being cheaper to buy and has a lower stall with same 134 knot cruise)

14 hours ago, Old Koreelah said:

Surely the only time a Bing carby will leaked is when the needle valve doesn’t seat properly?

Logic (?) would suggest that an opening (breather) in a vessel may allow a liquid therein to escape, if/when the bowl is subject to sharp movement and/or change of attitude. This train of thought has lead me to think that some fuel escape may be normal.

So far I have only had advise that no fuel should escape, in a correctly set up carburettor float bowl - counterintuitive?

To the best of my knowledge the causes of float bowl flooding (fuel overflow through breather) are -

• Saturated/ Heavy floats ie float that do not maintain the optimum fuel level solution replace floats (done!)
• Incorrectly located breather pipe - pressure difference causing fuel to be drawn into/out of breather (not in this case)
• Float/float valve armature incorrectly set - yet to check this out in brand new engine
• Float valve/needle not seating - foreign object keeping valve open (checked clear), fuel varnish on seat (not yet checked), valve tip damaged/warn (yet to check this out in brand new engine)
• Excessive fuel pressure, overcoming  inlet valve sealing, causing bowl flooding & fuel to be ejected through the breather pipe - fuel pressures (max 5.3 psi) are well within Rotax specifications.

Note: The only reason I know that, a very small amount of, fuel is being ejected, is because I have a catch can on each drain tube. My previous Rotax powered aircraft had no such accessory,  so I can not be sure a small amount of fuel may have been emitted.

McCarthyism is alive and well in the USA

How is that a virtually new airframe can not be utilised/converted for some other aviation purpose? (other than spare parts & recycled aluminium)

I purchased my, almost completed, home built, a little over 12 months ago. The yet to be installed ADSB-S  was purchased 4 years ago. This pretty well makes me/it ineligible for the grant. Such is life and the limits on Gov largess, when it comes to enhanced safety.