SonexBuilders.net

Hi all,

I hope you are able to assist with the following (even if its just best guess) - Sonex is a conventional/tail wheel with Rotax 912ULS

Best glide speed (engine out)
Vx Speed for of best angle of climb
Vy Speed for best rate of climb

Max Cross Wind
Max Tail Wind
Max Head Wind

Flap extensions in degrees (there is a reference to 10 degrees for 1st stage).

My thanks in anticipation

Clearly my anticipation was premature - doesnt anyone have anything to contribute to my question(s).

The information I am looking for is usually found in the POH but not in the Sonex one (little yellow booklet) that I have. Nor have I been able to find the information on the Sonex web site.

It's blank in the handbook because you are supposed to determine some of this stuff during your test flying, but Vne and maximum flap extension speed are stipulated by Sonex. Vne is 171 knots and maximum flap extension speed is 87 knots. Must confess I've exceeded that one quite a few times after take off.

Peter

Get the EAA Test Manual.It has step by step.How to check your air speed indicator, stall speeds, best climb etc.
Tom

I certainly get that you're required to determine the exact numbers yourself. I also know that unless you deviate from the design, or have a leak in your pitot static tubing, the numbers should be very close to the factory numbers. If they want to leave the POH blank, that's fine, but I think they should at least post the numbers for the factory plane. I would much rather have a ballpark number than nothing.

Rusty

Hi,

I'm unsure about one thing. Is your aircraft a Sonex or OneX? I've searched thru many of your previous posts and they refer to a OneX, but this request for POH numbers refers to a Sonex. The numbers will most likely be different.

Have you read the FAA flight test circular? It has some great advice on phase I flight testing. Even if you don't follow it exactly it will give you some ideas. For example it discusses how to estimate airspeeds, with that extra safety margin, during early flight testing. https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_90-89B.pdf

Does your aircraft have an EFIS made by MGL, Dynon, Garmin, GRT, or Advanced Flight Systems? If so consider using https://jasflyer.com/ which has some great tools to help you more easily collect the flight performance numbers you need for your POH.

You have mentioned that Sonex should publish all of their flight performance numbers. However, IMO, those numbers might be misleading. What if a builder uses a different engine? ULS? Different prop? And then there are pilots that would just use the Sonex numbers and never actually run their own flight tests to verify how their aircraft is performing.

Good luck with your flight testing. It should be a challenging but fulfilling time.

peter anson wrote:It's blank in the handbook because you are supposed to determine some of this stuff during your test flying, but Vne and maximum flap extension speed are stipulated by Sonex. Vne is 171 knots and maximum flap extension speed is 87 knots. Must confess I've exceeded that one quite a few times after take off.

Peter

Thanks Peter - I would guess we have all exceeded Vfe at one time or another.

I dont have aproblem with determining some of the V speeds myself but it would be helpful to have factory guidance.

My last aircraft, ATEC Zephyr (kit) /Rotax 912 ULS fitted with steam gauges, had all the V speeds, cross, tail & head winds supplied by the factory - they were pretty well spot on. My aircrafts stall was a little lower than factory spec, as was ground TO/landing role.

13brv3 wrote:I certainly get that you're required to determine the exact numbers yourself. I also know that unless you deviate from the design, or have a leak in your pitot static tubing, the numbers should be very close to the factory numbers. If they want to leave the POH blank, that's fine, but I think they should at least post the numbers for the factory plane. I would much rather have a ballpark number than nothing.

Rusty

Agreed 100 %

XenosN42 wrote:Hi,

I'm unsure about one thing. Is your aircraft a Sonex or OneX? I've searched thru many of your previous posts and they refer to a OneX, but this request for POH numbers refers to a Sonex. The numbers will most likely be different.

Have you read the FAA flight test circular? It has some great advice on phase I flight testing. Even if you don't follow it exactly it will give you some ideas. For example it discusses how to estimate airspeeds, with that extra safety margin, during early flight testing. https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_90-89B.pdf

Does your aircraft have an EFIS made by MGL, Dynon, Garmin, GRT, or Advanced Flight Systems? If so consider using https://jasflyer.com/ which has some great tools to help you more easily collect the flight performance numbers you need for your POH.

You have mentioned that Sonex should publish all of their flight performance numbers. However, IMO, those numbers might be misleading. What if a builder uses a different engine? ULS? Different prop? And then there are pilots that would just use the Sonex numbers and never actually run their own flight tests to verify how their aircraft is performing.

Good luck with your flight testing. It should be a challenging but fulfilling time.

Its most definitely a Sonex Legacy (A Model)/912 ULS, tail wheel, fitted with Airmaster CS prop - any reference to OneX would be from respondence to my questions.

Yes it does have a Dynon EFIS, which I have yet to get my head around.

My thanks for the suggestions - will follow those up.

True, builders preferences (engine/prop/weight/etc) will have influence each aircrafts performance however a base line example (factory aircraft) would be an excellent/helpful starting point.

Going by factory performance figures (usually conservative) should never be a problem UNLESS your aircraft is under performing - this would be good to know as there may be a safety issue, that should be addressed.

I have contacted Sonex and they have given me a little more to work with:

Vg 57 knots
Climb (neither Vx or Vy) 70 Knots
Demonstrated cross wind 20 Knots - no tail or head wind.

Mostly "motherhood" statements about pilot determined speeds based on personal skill. Recreational aircraft (Sonex) should not be flown/landed in conditions where tail/head wind components are a factor (I have a one way strip - small tail wind is a regular feature).

XenosN42 wrote:Hi,

I'm unsure about one thing. Is your aircraft a Sonex or OneX? I've searched thru many of your previous posts and they refer to a OneX, but this request for POH numbers refers to a Sonex. The numbers will most likely be different.

Have you read the FAA flight test circular? It has some great advice on phase I flight testing. Even if you don't follow it exactly it will give you some ideas. For example it discusses how to estimate airspeeds, with that extra safety margin, during early flight testing. https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_90-89B.pdf

Does your aircraft have an EFIS made by MGL, Dynon, Garmin, GRT, or Advanced Flight Systems? If so consider using https://jasflyer.com/ which has some great tools to help you more easily collect the flight performance numbers you need for your POH.

You have mentioned that Sonex should publish all of their flight performance numbers. However, IMO, those numbers might be misleading. What if a builder uses a different engine? ULS? Different prop? And then there are pilots that would just use the Sonex numbers and never actually run their own flight tests to verify how their aircraft is performing.

Good luck with your flight testing. It should be a challenging but fulfilling time.

Its most definitely a Sonex Legacy (A Model)/912 ULS, tail wheel, fitted with Airmaster CS prop - any reference to OneX would be from respondence to my questions.

Yes it does have a Dynon EFIS, which I have yet to get my head around.

My thanks for the suggestions - will follow those up.

True, builders preferences (engine/prop/weight/etc) will have influence each aircrafts performance however a base line example (factory aircraft) would be an excellent/helpful starting point.

Going by factory performance figures (usually conservative) should never be a problem UNLESS your aircraft is under performing - this would be good to know as there may be a safety issue, that should be addressed.

I have contacted Sonex and they have given me a little more to work with:

Vg 57 knots
Climb (neither Vx or Vy) 70 Knots
Demonstrated cross wind 20 Knots - no tail or head wind.

Mostly "motherhood" statements about pilot determined speeds based on personal skill. Recreational aircraft (Sonex) should not be flown/landed in conditions where tail/head wind components are a factor (I have a one way strip - small tail wind is a regular feature).