Stalls and Radio Exam!

[boingk]

What is the advantage of a T tail. Is it to move the stabiliser out of the prop wash? Move it out of the turbulence created when the wing is stalled? Stop clowns sitting their kids on it at airshows?

Yes, its generally to move it out of wing turbulence at speed or in a stall, and is part of the reason that WWII fighters sometimes were unable to recover from a dive; the phenomenon is called 'compressibility' and is caused by approaching the speed of sound and having the high pressure air at the front of the wing cause turbulence as it flows back over the airfoil, resulting in reduced or even totally negated elevator effecitveness in traditional layouts. Basically it makes for a control surface that is less likely to become ineffective at low landing speeds, high angles of attack or very high airspeeds.

 

It also moves the horizontal stabilizer out of the way of propwash, exhaust gas, or any other unwanted aerodynamic curiosities the aircraft may have.

 

Lark - most probably turbulators, common now on STOL aircraft and available as an add-on for many others.

 

 

[motzartmerv]

Yea, I don't think compressibility has anything to do with t tails in lighties. Also it was more the pressure wave In front of the horizontal stabiliser that caused the ineffective elevator, hence the all flyin tail on the bellx1. But like I said, that's pretty irrelevant to a tomohawk;)

 

 

[Ultralights]

that video was an incipient spin, not a fully developed spin.

 

plenty of skipper aircraft at Camden. Liverpool flying club operates them, well, they did when i last was there last year.

 

 

[speed_racer]

I found the stalls anti climatic as well.. I havent done advanced stalling yet but I'm learning in a jab 160.. when u drop off the power and pull back until the stall warning goes off.. it didnt drop forward like it was supposed too.. it just started to drop altitude but with the same AoA (falling flat).. Then when u move the stick forward, you pull out.. Perhaps its because the jab's are pretty forgiving in a stall? I was expecting the plane to drop forwards but nope, not within the hour of stall training..

 

 

[Ultralights]

What is the advantage of a T tail. Is it to move the stabiliser out of the prop wash? Move it out of the turbulence created when the wing is stalled? Stop clowns sitting their kids on it at airshows?

Most of the reasons for using a T tails are aerodynamic. mainly drag reduction. Just like the wing, the horizontal, and vertical stabilisers create tip vortices, and drag, with a T tail, there is only 2 tips, not 3. the top horizontal stabiliser works like a winglet for the vertical stabiliser.

having the horizontal part out of the prop wash also reduces parasite drag created by the additional airflow passing over it,

 

The negatives are structural, a stronger vertical stabiliser is needed to transfer the control forces to the aircraft as well as rudder forces. more complex flight control cable/rod routing as well.

 

The aerodynamic drawbacks come when the horizontal stabiliser is blanked by disturbed airflow from the wing at high AOA situations. this can be stopped by good design.

 

The main reason for their use is drag reduction.. just look at almost every high performance glider..

 

 

[Thirsty]

speed_racer - not wanting to frighten you but wait til you do stalls with a bit of power on and some flap out! You'll almost always get a wing drop in that situation and you need to see it and be able to deal with it. Do it often enough and it becomes fun!

 

 

[Jabiru7252]

Somewhere I have copies of tech documents wrt Tomahawk stalling and spinning. No failures of tail structure and no mods required for spinning - spin approval was never withdrawn by the airworthiness authority (FAA). More than a few lost due to spinning.One observation is that different examples behaved differently so not everyone encountered those with unacceptable characteristics.

I find it astonishing that we can have such opposing claims! Poor newbies to this forum must get so confused at times!

 

 

[turboplanner]

speed_racer - not wanting to frighten you but wait til you do stalls with a bit of power on and some flap out! You'll almost always get a wing drop in that situation and you need to see it and be able to deal with it. Do it often enough and it becomes fun!

Power off stalls are taught early in training (should always be taught before first solo), and in most aircraft are gentle a little more than mushing. You are usually taught to pick up the hint of a wing drop that occurs, and that is easy.

 

speed_racer and others, do not attempt full power stalls before you have been trained by an instructor because that same aircraft that was so easy to handle will do things so fast that most learners will be overwhelmed and slow to react. The nose attitude is much higher and when the AoA reaches the stall point you don't have the momentum you had in the downward mushing power-off stall, so the wing drop will be much more violent the chances of getting into a spin greater.

 

Even the most docile of aircraft, the Cherokee can become a monster in a power-on stall.

 

 

[dazza 38]

A full power on stall in a Savage Cub/Cruiser with VG's fitted is a great experience. Not for the faint hearted though.

 

 

[facthunter]

Bear in mind that the angle of attack is not represented by the pitch attitude, in a lot of the situations you will get when stalled, and that really you have little knowledge of what it is unless an indicator s fitted. or get the concept of a docile stall being characteristic of certain aircraft. Load them tail heavy or pull"G" and they are a horse of a different colour, particularly if the ball is not centred.

 

Regarding djpacro's comment . Many aircraft don't spin exactly the same each time and some get into a different attitude after a number of turns. They are more unpredictable and require more experience to effect a sure recovery . They respond differently depending on the method of entry and some spins may be unintentional so it takes a while with some people to recognise the plane is spinning.( Autorotating). The plane is not controllable in that state, so if you want to do something "normal" with it, the first thing is to recover from the spin. Nev

 

 

[djpacro]

I find it astonishing that we can have such opposing claims! Poor newbies to this forum must get so confused at times!

Some info available online here for a time http://www.ozaeros.net/tomahawk/ (sorry, some links don't appear to work properly so this extra link) http://www.ozaeros.net/tomahawk/The%20McCabe%20Report.htmOpposing claims? Easily checked via ADs and SBs etc such as http://services.casa.gov.au/airworth/airwd/schedules/ad_display.asp?session=884687933&pc=PC_90830&sched=under&toc=PA-38

 

 

[bilby54]

I think that there is a misunderstanding here as we are talking about stall recovery - wing dropping, yawing or whatever - not recovery from a spin.

 

The recovery from a stall is to rapidly get the stick forward to unstall the wing and get the aircraft flying. Most accidents occur because pilots try to stretch the glide during an engine failure and spin in. If you are below 500' agl then you should not buggerise around trying to pick up wings with rudder; shove the stick forward, roll the wings level and adopt best glide speed. If you are holding the stick back and the aircraft is stalled then you will never recover and yes you will spin and it happens very fast to unsuspecting pilots and if you are close to the ground you will die.

 

If you stall an aircraft shove the stick forward and maintain control

 

 

[Gnarly Gnu]

I found the stalls anti climatic as well.. Then when u move the stick forward, you pull out.. Perhaps its because the jab's are pretty forgiving in a stall?

Yeah, I can't get them to do much like that. Try some power, maybe some flap and a decent nose-up attitude then chuck in a turn.... (with instructor of course - an agreeable instructor). Skidding turn if you need a clearer demo.

 

 

[facthunter]

I haven't discussed RECOVERY from a spin except to say you will need to do it if you get into one. Spin recovery discussion is not for here. ( as far as I am concerned) as it is contentious and varies with type and situation and our planes are not certified to perform spins.

 

Stall recovery is attained by reducing the angle of attack and it unloads the wing so the plane may fly unstalled (and therefore controllable) at low forward speeds, simply achieved as DJP says by moving the stick forward. I would advocate power being applied too to avoid excess height loss, provided the nose is near horizontal or above. Most basic stall training/recovery is done without using power, a technique which should be reconsidered if available height is a factor, as it will be in most real situations. Nev

 

 

[tafisama]

The advice given in this post has been retracted by the author.

 

Moderator.

 

 

[djpacro]

Yes,our aircraft are not certified to perform spins ....

Our aircraft can be certified to perform spins eg the two types mentioned already in this thread: C172 and PA-38.

 

............ but if we accidentally get into one,we need the tools for recovery in our bags.I have often heard the first step is stop rotation by opposite rudder .................................Now we have added a tool to our bags.

Nope, that is not the first step. Suggest you do very much more reading to obtain the correct info. Do a spin course if you really want to believe you have such a tool.But then, we weren't discussing spins here. Sorry, my favourite subject.

 

 

[motzartmerv]

.Now we have added a tool to our bags.

PPhheewww. I was getting worried.:)

[bilby54]

Yes,our aircraft are not certified to perform spins but if we accidentally get into one,we need the tools for recovery in our bags.

And now you have just entered the world of the test pilot with the exception that they have extensive aeronautical knowledge and flying skill. Have a defined routine for the test sequence, have a safety plan for when things go wrong, a spin recovery shute and a parachute for when everything goes pear shaped.

 

There is no such thing in RAA registered aircraft so do as DJP has suggested.

 

There is a lot of dodgy info being presented here and the topic is STALLS which are recovered by pushing forward on the stick. If one wing drops or yaws because it has stalled before the other wing then the recovery is the same - push the stick forward to unstall the wing. The biggest mistake that people make is thinking that because they practiced at high altitude then "if they get into trouble and accidentally enter a spin" they will be able to get out of it. Do not ever think along that path because at low level you will die.

 

A spin entry at low level is fatal - a Drifter will lose around 400' in one rotation in controlled circumstances, metal skinned aircraft just spin quicker so how is anyone going to survive when they have had an engine failure at low level? Trying to stretch the glide and spin in at 100'? Take a wander through Youtube just to clarify that. Have a look at the safety statistics (RAAus excluded) and see how many people have died as a result.

 

The RAA syllabus covers Stalls with 'wing drop'. If the aircraft is held in the stalled configuration it will spin so why do it?? Schools should teach stall recognition and how to avoid getting into that situation in the first place because the average garden variety pilot will die if they enter one. I have had more than enough experience with that side of things thanks.

 

There is not enough emphasis placed on slow flight and stall recognition as a certain element seem to think that students are not real pilots until they have recovered from a spin at 5000' in an aircraft that is not approved and quite willing to put YOUR life in real danger.

 

It does not matter where the stall occurs, just remember to get the stick forward to unstall the wing and continue flying and if it is because of a forced landing then you will most likely survive. If you stall and then spin........

 

 

[tafisama]

PPhheewww. I was getting worried.:)

I am sorry for my over excitement to post what I have heard especially when its something that shouldnt be even discussed at our level.I wanted to withdraw the post but I cant.I accept my blunder.

 

 

[motzartmerv]

Don't worry mate. It's all good. :)

 

 

[kaz3g]

I did my first stalls (and spins and spirals) in a Tomahawk, that gets the sphincter going!

Yes... They are not as easy a Warrior or C172, that's for sure. But they were designed to be able to demonstrate what spinning is all about.

 

My first landing was an experience because I let my speed drop to around 60 knots over the fence and it suddenly stopped flying about 6' off the ground. Once the throttle was chopped and the nose lifted, the T tail elevators didn't respond as expected (by me). Embarrassing!

 

Kaz

 

 

[facthunter]

It is reasonable to be wary of stalls but not frightened. I have found many who are terrified of getting slow, but would not be truly aware that in some situations even a higher speed will not protect you from stalling the plane, because it is an angle of attack thing. But of course we all know that don't we? Sure How long since you did dual with someone capable and stalled off a turn with and without power. It's worth thinking about because that is where you will get bitten, if your awareness diminishes under pressure or inattention. Nev

 

 

[kaz3g]

Some info available online here for a time http://www.ozaeros.net/tomahawk/ (sorry, some links don't appear to work properly so this extra link) http://www.ozaeros.net/tomahawk/The%20McCabe%20Report.htmOpposing claims? Easily checked via ADs and SBs etc such as http://services.casa.gov.au/airworth/airwd/schedules/ad_display.asp?session=884687933&pc=PC_90830&sched=under&toc=PA-38

I was signed off on the Tomahawk by Jack Jarden who has been instructin in them for many years. I seem to recall a number were fitted with Stall strips (?) close inboard to get the wing root to stall first and make for a more certain recovery.

 

When I was into gliding instructing, we had mandatory spin training and the procedure was stick forward to unstall the aircraft then full opposite rudder to stop the spin and then recover from the dive without ripping the wings off.

 

I used the same when doing a basic endorsement in Ian Sharp's old Decathlon, BIK ...BUT not all aircraft are the same and you need to understand the foibles of the particular machine you are challenging Nature in http://www.ozaeros.net//spin/beard.htm

 

(Edit note: I have never done an inverted spin or a flat spin and I should have added that in a powered aircraft the throttle is closed during the recovery)

 

And I recommend basic spin training to everyone. Do it with someone like DJP and add that skill to your personal SMS.

 

Kaz

 

 

[djpacro]

Tomahawk revised stall strips (to improve handling at the stall) was an Airworthiness Directive in 1979.

 

In a fully developed spin in some GA types, stick forward before opposite rudder will delay or even prevent recovery from the spin. Just a quick look here http://www.recreationalflying.com/threads/decathlon-accelerated-spin.64556/

 

 

[speed_racer]

My first landing was an experience because I let my speed drop to around 60 knots over the fence and it suddenly stopped flying about 6' off the ground. Once the throttle was chopped and the nose lifted, the T tail elevators didn't respond as expected (by me). Embarrassing!Kaz

Lol I had the opposite problem, I come in too fast and when i flare i end up floating half way down the runway hehe