The International Cessna^® 170 Association

I have been unable to find much info on spins by using the "search" feature. This topic must have been discussed before, right? If anyone that has experience with spins in the 170 would like to share their knowledge, it would be appreciated.
Number of turns? recovery technique? airspeed after recovery?
Thanks

Well, since no one else has responded to this one (suprisingly) I guess I'll throw out what little experience I have spinning the 170.

I've owned my 52 B for four years, but because I installed a new attitude indicator, I've never spun it - in theory, it shouldn't hurt it, but in practice, I'm the guy paying for a new gyro!

But way back in 1974, I did spin a 1955 170B I was instructing in. No problem with those gyros, they were the old AN style you caged before such shenigans. About the only thing I remember is that it had the same spin chracteristics as an early 172 - very predictable entry and recovery.

It sounds like you have had experience spinning other airplanes, so the only advice I would have is: don't start below 5,000 AGL (at least), gross weight within the utility category, and unless a CFI is involved, I believe you legally need parachutes - I'm too lazy to look up the exact regulation.

I wouldn't let it do more than about 2.5 to 3 turns, just to be conservative.

In the course of instructing years ago, I have done spins in Cessna 150s, 172s old and new, a 170, J-3s, Champs and Citabrias, T-crafts and an aerobatic version of the Beech Sundowner, without problems. The last time I spun any airplane was a Schiwitzer 1-34 sailplane back in 1983 - it started going flat about two turns in, and took three turns to recover - for some reason, I haven't done any spins since! Russ Farris

The first year when I learned how to fly I owned an Aeronca Chief that I got quite used to spinning. The next year, I think 1975, I owned a 170A that had a few more stress wrinkles on one wing than was normal but had been pronounced airworthy by my IA at the prepurchase annual. That Summer I was fueling up while on a long cross country (at Spokane from Seattle) and when I went in to pay for the fuel a fellow there said "hey I used to own that 170. It sure loops good". Rather unsettling to me at the time. I did spin that plane a bit though and they spin very predictably. I don't do it now because of the gyros.

Every pilot should be comfortable getting out of spins instinctively without having to think about what to do. Sorta like our feet on landing.

Bought 1478D when a student pilot and we did a couple of spins of 1 or 2 turns. Would like to do more so the comfort level is better, but wouldn't want to damage gyros, etc. With an instructor on board, recovery was very simple, although it was very easy to allow G's to build when pulling up after leveling the wings.

My instructor taught us spins before we soloed and it was a form of enjoyment for us. He would let us spin the champ, 140, and luscombe all we wanted. He was quick to teach us that it is a precision maneuver and would not let us do anything until we understood them. He expected us to hit a heading on recovery everytime. If you don't set things straight in your mind before hand it is easy to get lazy and dangerous. Never do half turn recoveries because they tend to be more vertical or even inverted on early turns. It would take too long to pull out and you'd gain enough speed to overstrees the airplane. If you are in an aerobatic airplane and plan to recover inverted it make sense to recover on the half turn for the same reasoning. I have spun airplanes with big tire, skis, and even floats the 170 on small tires is a simple spin entry and recovery, but you still need someone with experience to show you the ropes. If you need to ask questions on this forum then you need a qualified instructor.

I hate to give information here on entry and recovery, since it could be used to go hurt yourself or others. But I would be glad to fly with you and show you the ins and outs all you want.

Kelly

Thanks to all for sharing your experiences and advice. My last plane was a Taylorcraft which was very easy to spin and recover. Recovery could be made without the airspeed going over 85mph. I thought (guessed) the 170 would have a slower spin rate but would build more airspeed on recovery.
My 170 spends most of the year on floats & ski's, so spins are out during this time. ( I have spun the T-craft on ski's but the 170's ski's are alot bigger).
Kelly you are right, there's no subsitute for a qualified instructor.
Brian

There is one other thought about spins, it might be best to practice them in warm weather vs the winter time so there is less rapid cooling of the cylinders when power is rapidly reduced.

OLE GAR HERE*&%(((&^

Had to stuff him back in the box for a while.

Spinning a 170 A or B is a delight because of the powerful elevator and rudder control. Precise entry and exit (stopping on a heading) is very predictable in our 170s. Only one word of caution - - do not "push" forward on the wheel. Neutral elevator and quick opposite rudder input will make her recover quite nicely' thank you. Too much of a strong "push" forward will put you inverted. The 'A' models and the '52B have the "down" angle on the top of cowl and that accentuates the "vertical" feeling in a spin.

No parachutes are required for spin training.

Joe, the "shock cooling" is of very little consequence because the ram air is not being forced over the cylinders as much in a spin as in level flight and we do not use cruise airspeed to enter into a spin. The entry is just above the full stall. Therefore the power has been reduced for a slight cool-off before the entry. She likes left turns spins better than right but will act very predictably both ways. Enjoy - and if you have spun other planes, outside of aerobatic, you will find she has no equal. Compared with those other planes )(&(%%++)(* NO CONTEST! WHEW! I GOT OUT JES IN TIME TO WISH Y'ALL A MERRY CHRISMAS AN TO ALL Y'ALL HAPPY NEW YEEAR YEEE HAAA.

Some of the conventional wisdom on so-called "shock cooling" has struck me as dubious for some time. Maybe someone can explain why flight through rain doesn't destroy an engine - now that's a massive amount of "shock cooling" going on there! Just trying to start something on Christmas eve...Russ Farris

Not an expert, not even very smart, but I do like to study and read about it. The cylinder is an aluminum alloy with other parts like the valve seat being other materials as an example. The expansion/shrinkage rate of aluminum is very different than steel/iron. The loose tolerances of our engines allow for the different expansion/shrinkage rates to last a predetermined time before failure. That is, as long as it is not an unacceptable rapid rate of heating/cooling. On a cold start, the different materials expand at very different rates, and this is one of the reasons pre-heating is so effective on reducing engine wear. Shock-cooling is a loosely applied term sort of like a pre-buy inspection. It has very little real meaning. But, if you have a hot engine at altitude, and the power is reduced rapidly vs stepping down with small power changes, the built in tolerances such as in the force fit valve seats can cause a crack to form in the cylinder, or accelerate when it will crack, because of the different shrinkage rates. Rain actually makes our engines run better and gives us a slight boost in power. It's not the cooling of the fins, they are all of the same material, it's the inside of the engine/cylinders that can be a problem. Maybe if you tried to make abrupt power changes in rain vs no rain it would be a quicker problem, not sure. To sum it up the way I understand it: Due to the material used, lightweight and strong, but susceptible to cracking - the cylinders WILL crack at some time but usually not before 1800 hours if operated correctly. The design and engineering has built in tolerances that allow for the continuous shrinking/expansion of normal use. But everytime the shrinking/expansion RATE of change is greater than that designed/engineered for, it accelerates the time to failure.

It is good technique to smoothly transition from one flight regime to another, such as well-planned descents that avoid abrupt power changes.
But, ...if shock cooling hurts an engine....then what does it do to an engine to apply take-off power? There's no greater rate-of-change in temps than those that occur during the takeoff roll.
Strange, no one seems to advocate spending the time to advance the throttle the one inch of M.P. per minute that the "shock cooling" crowd claims is necessary for power reductions.
I'm one of those that view "shock cooling" as a psuedo-myth. I wouldn't deliberately cruise at high-speed and "yank" the throttle off and dive at red-line,....but I don't subscribe to the theory of "shock-cooling" as an axiom of early cylinder/engine failures.
The cylinder cooling fins are made up of the same material as the cylinder sections: Barrels are steel and heads are aluminum, as are the cooling fins in that area. Aluminum expands faster and shrinks faster than steel in a generic sense, but the reason aluminum is used for cylinder heads is specifically because of that property. That's where most of the heat is located. Aluminum is so efficient at conducting heat away from the engine is the very reason it's used for cylinder heads, and get this, until a British engineer named Heron invented the idea of threading aluminum heads onto steel cylinders,... most engines used all steel cylinders and heads or they used bolt-on heads, and they suffered early and frequent cylinder head cracking. The threaded and shrunk-on aluminum heads solved the problem. (The J-5 Whirlwind that got Lindbergh to Paris was one of the first engines to use the newly patented design.) Higher incidents of cylinder cracking came about after engine's TBO's were elevated from operational experience and cylinders became widely re-used over and over again for economic reasons (especially during/after WW-II due to shortages...that's when/why chroming was developed and became popular.) Those overly-reused cylinders became cycle-stressed.
Now that new cylinders are commonly available at affordable prices, the simpler engines such as the O300's with fixed pitch props and no turbos/gear-boxes should begin to disprove the old psuedo-myth. (ACOOM) (Another Crazy Opinion Of Mine)

In any case, a spin is nothing more than a stall that the airplane has been held
into while yaw is introduced. The airplane is stalled the entire duration of the spin. If it's OK to idle the engine to perform a stall without injuring the engine, then the engine knows nothing different about the spin.
The recovery is nothing but a stall recovery AFTER the rotation has been stopped with rudder. (At which time the elevator is relaxed to nuetral in order to reduce the angle of attack, same as any other stall recovery, i.e., don't "dump" it.)
It's important to learn spins from a qualified instructor who knows how to teach them. Just because an airplane is "approved" for spins doesn't mean a spin can't be mishandled to the point of impact. More than one (including at least one Cessna factory test pilot) has died spinning airplanes that were "approved" for spins. Seemingly very minor changes in aircraft configuration and condition can make a "spinnable" airplane into a non-recoverable one. (Cessna had an entire group of fresh production airplanes develop spin-recovery problems simply because the factory tooling which set the horozontal stabilizer's leading edge had become worn due to the numbers of airplanes produced. The slightly worn tooling and the airplanes produced with it were virtually un-discernable from the 100's of sister-ships that same tooling had produced. Moral: Don't be afraid to learn them properly, but don't take spins lightly either.)

I'm not sure I agree with you that take-off has a greater rate-of-change in temps than going to idle at altitude, because at take-off, you are increasing heat-creation as well as increasing heat dissipation capability via higher-speeds.

A taxi to take off involves going from

1) low-cooling (no airflow to speak of over cylinders) but low heat production (close to idle)

to

2) much higher cooling but high-heat production for a very short time period

You're moving from a low-heat/low-cooling to a high-heat/high-cooling transition. I see this as: the balance of heating and cooling is closer for this transition than for a cruise-power to rapid-descent at idle situation.

Where shock-cooling would come into play is

1) a high-heat production and high cooling

to

2) very low-heat production and high cooling for a much longer time period

This transition is a high-heat/high-cooling to low-heat/high-cooling and is much less balanced than the idle/taxi to take-off power.

This leads to my thinking that shock-cooling can be a problem, and to just takeit easy on the engine, especially at altitude where the air is cooler than ground level (given no temp. inversion...)

Now all of this has to take into account that more heat will be produced in high-power engines than in low power engines. Given what I've stated above, a 0520 engine will have more of a problem than a 0300 engine.

How this would apply to a spin would be going from high-heat production and high-cooling to low heat production and low cooling capabilty.

Just my thinking on it, no I haven't actually run the numbers. I'm reinstalling the computer that could do that

Brian

Quick question, how differant is the spin characteristics of the Ragwing as opossed to the A and B models?

All good thought processes, Brian, but altitude has less to do with it than one might imagine. (The greatest cyl. temp-change occurs at the thinnest, least dense altitudes (air densities.) During the descent to dense, cooling air the cylinder has already stabilised it's internal temps.
"Shock" cooling/heating (we'll all have to agree for the purposes of discussion) refers to a large, rapid change of temperature over a short period of time. "Cracking" is caused by 1: erosion due to hot gases and/or 2: large dimensional changes beyond the elasticity of the object. The largest change in both temperature and dimension occuring over the shortest period of time is in the 3-6 seconds that takeoff power is applied, sending EGT's from 600 or less to 1400 or more in only moments. This might be the scenario for erosion.
As for dimensional changes, I believe the takeoff power application is a far larger "shock" to the engine than the reduction of power/descent scenario and here's the reason I believe this view to be valid.....
ALL of us are forced to apply takeoff power rather rapidly due to runway length constraints. Relatively few of us are so lacking in a desire towards smoothness-of-flight that we reduce power in such a rapid manner. It's unfortunate we can't perform a few hundred descents without the necessity to takeoff first. If we could, then we could prove (or disprove) this theory.
I can't help but notice that flight-training airplanes, which typically have huge cowling airflows (and typically with no cowl flaps and therefore less engine cooling regulation) and which are frequently exposed to flight-idle operations (stall demonstrations/practice) suffer less from cracking cylinders than high-performance aircraft more likely operated by more-experienced or professional crews who rarely practice rapid in-flight power reductions at high speed. The most remarkable difference which occurs between the two aircraft types that I can think of are the higher rates of temperature increase (from takeoff power application) that occur to the high-performance aircraft (frequently turbo'd) while trying to get airborne in the shortest distances/periods of time. In 35 years of professional flying I've never demonstrated stalls to passengers in corporate aircraft, yet those are the airplanes which have the highest incidents of cylinder cracking.
Since stall/spin demonstrations are a planned event, and since such demonstrations are usually performed in a methodical, deliberate manner (i.e., carefull power reductions and deceleration rates in order to produce the desired 2 kt-per-second deceleration req'd by most training programs and FAA tests), I don't see it as a "shock cooling" hazard. Accordingly, I do not believe stall/spin demonstrations are a high risk to cylinders.
(For those unfamiliar with spins let me explain that a spin is firstly, a stall, with rotation produced by a yawing motion. It is demonstrated by qualified instructors to students as part of flight training in single-engined Cessnas in the following manner: At a safe altitude (say 5K feet or more) the airplane is trimmed for slow flight. The power is reduced to idle as in a simple, straght-ahead, flaps up stall demonstration. Altitude is maintained to produce the stall. The elevator/yoke is held full up/back as the moment of "break" due to stall occurs, and the elevator/yoke is held fully back throughout the manuever. (This is important to keep the airplane stalled and prevent dangerous airspeed build-up.) The moment the "break" occurs full rudder is applied in the direction of desired rotation. The airplane will appear (from the cockpit view) to roll upside down, drop it's nose towards the ground, and rapidly begin a rotation in the direction of applied rudder (which is held fully applied in the direction of rotation along with full-up elevator.) The airplane is completely stalled and the indicated airspeed will not appreciably increase due to the stalled condition. The descent and loss of alittude however, will be rapid.
The recovery is performed in a similarly methodical manner in a prescribed order of actions. FIRSTLY the rudder is fully applied OPPOSITELY to rotation until rotation is stopped. The rudder is then nuetralized. Only then, after the rotation has been stopped, is the elevator also nuetralized, exactly as in a stall recovery....for that is exactly what is being performed at that point....a stall recovery.
The now-flying airplane is decidedly pointed at the earth and the loss of altitude will rapidly increase along with airspeed. It is important to gently and measuredly raise the nose with elevator to bring the airplane to a level flight altitude, and only then... re-apply sufficient power to maintain level flight. It is not uncommon to lose 2 thousand feet or more in the manuever. The first-time student will be very distracted by the cockpit view throughout the manuever...and that is a major reason one should not perform this manuever alone until your instructor has demonstrated it to you sufficiently and until he authorizes you to do it without him.
Stalls/spins are not a manuever to go out and play with or demonstrate to family and friends. They are an aerobatic manuever to be left to instructors for flight training purposes and to aerobatic pilots in aerobatic airplanes....not for our 170 "businessliners" to be regularly subjected to. These airplanes are 50 years old or older and the stresses from spins are cumulative. You can only bend a paperclip so many times before... ... (What's in your hidden, aft bulkhead area?)

George, that was very enjoyable reading - THANKS! And, very valuable information to have.

It still seems like the temperature changes the engine would go thru would be even more than practicing stalls(for one, you loose alot more altitude so there is more time at idle), and that the colder the weather, the more change in temperature.

It sounds like you have not seen any, or very many, cracked C145/O300 cylinders.

The Commanche drivers on my taxie row with the choked cylinders do very long warm ups in winter time before takeoffs.