Spinning a Sonerai?

[Flyingfool]

Since some folks do some limited aerobatics in Sonerai. I was wondering if the design had been spin tested. Especially with the original smaller tail and rudder?

I am not saying this should be done intentionally all the time. But from my understanding falling out of a loop or some other maneuver could end up in a spin.

Just wondering as the rudder “looks” pretty small. But looks are often deceiving.

 

[kennyw]

I have done some of the limited aerobatics described in the POH that came with 4SP. And, the result of "falling out" of any of those maneuvers was ending up nose low with airspeed quickly building. I think if you use conventional unusual attitude recovery techniques, you really don't need to fear an unintentional spin in this situation.

I have done the "falling-leaf" several times with 4SP just for fun. I can keep it in a deep stall, straight ahead, with small rudder inputs, stick full back, ailerons neutral. The rate of descent builds to about -1500 fpm. And, the stall is so benign that, I believe to get it into a spin would require aggressive pro-spin inputs.

I haven't done spins. Because, I don't wear a parachute. And, I don't feel comfortable doing them without one. I don't wear a parachute because there just isn't room. with a parachute on, I can't get full aft stick travel. And, I'm not sure I could even get of the airplane very quickly with one on anyway. So, all my maneuvers are very conservative; and, no spins.

 

[tls258]

You might want to read this before embarking on a spin test program. https://www.mypilotstore.com/MyPilo...qZdFCgcgH2Yx1HHOC09O-YyucKxb6pMBoCMnUQAvD_BwE

 

[Flyingfool]

With the a availability of AOA indicators at reasonable prices could dramatically improve and reduce stall spin accidents.

How the FAA does mandate the installation of an AOA on factory aircraft is beyond me. The additional cost for an AOA on a price of a new aircraft that are well into six figures is incidental and insignificant.

It may even make sense to retrofit an AOA onto a Sonerai. Outside of shoulder harnesss might be the single best safety enhancement that could be made. Can also set up more stabilized approaches and max glide performance.

 

[John B]

I've spun mine. Been a long time ago, like 25 years ago, but from what I remember I never did over 2 turns and it recovered quickly.

 

[tls258]

It may even make sense to retrofit an AOA onto a Sonerai. Outside of shoulder harnesss might be the single best safety enhancement that could be made. Can also set up more stabilized approaches and max glide performance.

Makes perfect sense. Other than looking outside for situational awareness, the AOA is the most important instrument you can have taking off or landing. If you pay attention to it, you can never stall or spin it in due to pilot error. All of the heavies have them. FAA thinks it's so important that the rules for installing are very lax.

 

[DeadRinger]

Spinning an airplane can throw all fluids away from pickups. Just a word of caution among other aerodynamic and CG/ aero concerns. I’d have a chute on me and one on the tail if I was really testing that type of stuff. Refer to NASA tests on the Grumman aa1a.

 

[shocktrooper]

Spinning an airplane can throw all fluids away from pickups. Just a word of caution among other aerodynamic and CG/ aero concerns. I’d have a chute on me and one on the tail if I was really testing that type of stuff. Refer to NASA tests on the Grumman aa1a.

Thx for the cool vid dRinger! I always enjoy classics like this from out of the time vaults.

 

[shocktrooper]

You might want to read this before embarking on a spin test program. https://www.mypilotstore.com/MyPilo...qZdFCgcgH2Yx1HHOC09O-YyucKxb6pMBoCMnUQAvD_BwE

....as I recently posted here on a different thread...Stick and Rudder by Wolfgang Langewiesche is also a wealth of knowledge and advisories of ‘whodathunkit’ scenarios on “ how to NOT inadverdantly spin-in”. I’m seriously considering installing a basic AOA system on my 2L this summer.

 

[kennyw]

Spinning an airplane can throw all fluids away from pickups. Just a word of caution among other aerodynamic and CG/ aero concerns. I’d have a chute on me and one on the tail if I was really testing that type of stuff. Refer to NASA tests on the Grumman aa1a.

I don't think most of us would consider trying to set the world record for inverted flat spins, or try testing out aggravated spins from high-G stalls or such.

A simple 1 1/2 - 2 turn spin is perfectly safe in an aircraft that is designed to have normal spin recovery characteristics. If I could get my fat ass in the airplane with a parachute on and still have full control throws, I wouldn't hesitate to spin a well built Sonerai.

 

[tls258]

Stowell's book is the most cautionary tale about spinning. Lot's of information and close calls and explanations. Bottom line is: If your aircraft has not been through a thorough spin protocol that explores all possible spin configurations and passed with flying colors, then you are risking your ass spinning it without a BRS. You can't realistically bail from a Sonerai. Compare these two spin scenarios, one with and one without a BRS, then decide what your butt is worth to spin test your bird:
http://www.kathrynsreport.com/2013/08/kr-2-plane-crash-near-cataldo-idaho.html

https://tinyurl.com/y9ab9dro
One thing worth noting in both crashes is that the pilots did not use the PARE technique to recover from the spin. They chase the inputs and never hold them until the spin stops then recover the dive. Stowell describes the technique in detail in his book. Also summarized here and other places: https://www.boldmethod.com/learn-to..._comment_id=1013155752060034_1014152311960378

That said, there are some configurations of aircraft that cannot be recovered from an established spin. Then, you either must chute yourself or the aircraft. Since every Sonerai is unique, you really don't know what you have if you want to test it spinning. You will be your own guinea pig.

 

[kennyw]

...That said, there are some configurations of aircraft that cannot be recovered from an established spin. Then, you either must chute yourself or the aircraft. Since every Sonerai is unique, you really don't know what you have if you want to test it spinning. You will be your own guinea pig.

First off, the Sonerai design is intended to do simple asymmetrical stall/spin entry of the type that would be done for Sportsman class aerobatics. Here's a screen shot from the POH that came with 4SP:

Secondly, you are a test pilot anytime you do something in your experimental airplane that has not previously been tested and documented. That's the fun part!

There's actually established procedures for doing it. If anyone wants to do a phase I spin test program on their Sonerai, and aren't sure how to go about doing it, here's a good reference:

"Flight Testing Homebuilt Aircraft" , Vaughan Askue

Chapter 10 has the whole spin test program laid out for you, including a good primer on spin aerodynamics.

I also recommend getting some aerobatic instruction if you've never done aerobatics or spins.

 

[M61A!]

Sorry deleted due lack of relevance

 

[tls258]

Here's a screen shot from the POH that came with 4SP:

One could put their trust in a POH written by an amateur builder who took 10 years to build a very nice Sonerai that was then modified by the next owner. I have never seen a video of Scott spinning 4SP. Everyone has their own level of acceptable risk. Personal minimums or maximums. I'll admit my risk acceptance is lower than many amateur-built pilots, but higher than say a friend who looked at my Sonerai and told me I was crazy to fly in something like that. On the other hand, those people who jump off mountains in wing suits accept very high levels of risk. If the risk of spinning a non-certificated, modified, amateur-built aircraft without a BRS is where your head is, go for it. But I would not advocate for others trying it. Here's a video link to a couple of risk-takers nearly spinning an Extra 330 into the ground:

 

[DeadRinger]

Crazy people. I rent a couple kids spinning a 172 to see how many they could do before hitting the ground. They didn’t make it. I think it crashed near alpine California. Do people think they can get away with more and more risk because they survived last time? Anytback to spinning Sonerai.

 

[Flyingfool]

Must have been an out of rig, or outside utility category Weight and/or CG for a 172 to remain in a spin.

I did my spin training for my CFI I’m a 172. And despite deliberately trying to keep it in a spin, making zero anti spin recovery control inputs. I could not get past 2 rotations! It would stop spinning and be in a steep decent. If trimmed to cruise it actually automatically Egan pulling up out of the dive as the sled was higher than trim setting. If anything I had to push forward on the yoke to reduce the nose up rate to not put on more G than was necessary.

This was after high nose up left rudder and applying some RPM to add torque to get into a pretty aggressive spin. I kept FULL in spin rudder and it still would not spin past 2 turns. I think it was closer to 1-1/2 rotation and it recovered.

Honestly it was NOT good spin training because the pilot had to do nothing other than manage the pup up to level flight from the nose down pitch Attitude after the rotation stopped.

I know to get the 172 into utility nothing in rear seats or baggage and I believe it was like half fuel in each wing tank.

Intentional spins in normal category is prohibited in the POH. Only allowed in utility category and the weight and CG to fit in the utility category POH envelop.

My original question which I was not specific about was with the short (non stretch) fuselage and original plan sized verticals stabilizer and rudder. As to my anecdotal visual eye, the tail surfaces appear a bit undersized. I would ASSUME (which is dangerous to do) if the “to spec” plans built plane with proper control stops settings could within rear CG limits recover from a spin. Then planes with larger vertical stabilizers and/or rudder theoretically should also recover as well if not better. Certainly no guarantee!. All bets are off if the turtle deck was raised. Unless otherwise Specifically tested. As it seems many report that with higher turtle deck that rudder authority and stabilizer is less effective and recommended larger and taller vertical stabilizer which would seem to make spin recovery also less effective or maybe even ineffective altogether!

Without a canopy that can be jettisoned. I have my doubts about the ability to successfully bail out of a Sonerai. Which makes the BRS idea a much better consideration for anyone wanting to spin test. But then the CG of the weight and logo of the BRS unit also has to be taken into account.

 

[John B]

The OP never said anything about spinning a modified Sonerai. He asked quite simply"

Since some folks do some limited aerobatics in Sonerai. I was wondering if the design had been spin tested. Especially with the original smaller tail and rudder?

The simplest thing to do is just call or email Sonex and ask them. After all, they have the design rights and the guy that designed the darn thing is still around. If anyone really knows what actual spin testing has been done, he (John Monnett) will.