spins, spirals

767 · Post by **767** » Wed Jul 19, 2006 1:01 am

How was your first experience? When i did my intro flight, I asked the instructor to demonstrate stalls, spins, and spirals. Unfortunately, he said the fuel tanks were full and he could only demonstrate a stall. So he showed me a power off (engine idle, or whatever its called) stall. I was also wondering what does the fuel tanks have to do with demonstrating spins/spirals?? What if in real life i enter a spin with full tanks, will i say to myself that my tanks are full therefore i cant recover from a spin?? Or was this instructor just scared of spins?

Thanks..

chipmunk · Post by **chipmunk** » Wed Jul 19, 2006 4:43 am

Hi there
Full fuel = heavier aircraft.

In some aircraft, intentional spins are only certified if the aircraft is below a certain weight (in the "utility category"), basically to avoid extra stresses on the aircraft during the maneuver.

If you entered a spin in real life with full tanks in that aircraft, you'd be able to recover, but your flight training will teach you PREVENTION - i.e. you'll be required to demonstrate the warning signs that lead up to a spin (and a stall, for that matter, because if you prevent a stall you'll prevent a spin) and recover BEFORE it happens.

Hope that helps, and enjoy your training.

fougapilot · Post by **fougapilot** » Wed Jul 19, 2006 4:48 am

Most small airplane have two weight categories: Normal and Utility. When the airplane is heavier, it falls in the normal category. When lighter it may fall into the Utility one. Different maneouvers are authorized in each categories. It is not that the airplane will not recover from them at the heavier weight, simply that doing it will put more stress on the airplane components. Therefore to minimize the impact of flight training on the airplane, the manufacturer imposes limitations to pilots. One of which is no intentional spins/spirals in the normal category. Its has been a long time since I flew a Cessna or Piper single engine, but having full fuel tanks on an airplane equipped with long-range fuel tanks could easily put it outside the envelope for these manoeuvers.

Hope this helps,

Dan

fougapilot · Post by **fougapilot** » Wed Jul 19, 2006 4:51 am

Well I guess Chipmunk beat me to the "Submit" button

chipmunk · Post by **chipmunk** » Wed Jul 19, 2006 4:53 am

At least we agree!

niss · Post by **niss** » Wed Jul 19, 2006 7:56 am

What kind of experience did you guys have putting a Cherokee 140 into a spin? Is it tough to do?

Hedley · Post by **Hedley** » Wed Jul 19, 2006 12:00 pm

um .... there is a POH/AFM and placards for your aircraft - what do they say about spins?

Some Cherokees are placarded against spins, and others are not.

READ YOUR POH. Cherokees are very finicky with respect to weight and balance, to be legal for spins, and have acceptable spin recovery behaviour.

Frankly, spinning your antique Cherokee is like taking your grandmother to a gang-bang. You could do it, but don't you think it might be a bit hard on the old girl?

Lommer · Post by **Lommer** » Wed Jul 19, 2006 2:14 pm

I've tried spinning a cherokee 140 (in the utility category, and with NO flap, as per POH). I found it nearly impossible to do - the damn thing wouldn't keep spinning; it kept going into a straight dive instead. The most I could get it to do was one rotation, barely, with the worst control inputs possible (from a recovery POV).

Spokes · Post by **Spokes** » Wed Jul 19, 2006 8:44 pm

I've got a student who owns a Cherokee. I am 220lbs, he nearly 200. We cannot even get this a/c into utility.

Xenophobe · Post by **Xenophobe** » Fri Jul 21, 2006 12:21 am

Walker · Post by **Walker** » Fri Jul 21, 2006 1:51 am

Heheheh, you should try spinning a Katana some time

For your enjoyment:
http://vids.myspace.com/index.cfm?fusea ... 365974&n=2#

Lurch · Post by **Lurch** » Fri Jul 21, 2006 11:18 am

Walker wrote:Heheheh, you should try spinning a Katana some time

For your enjoyment:
http://vids.myspace.com/index.cfm?fusea ... 365974&n=2#

You know it's good when a man giggles like a little girl

I just had a discusion the other day with another instructor about spinning a Cessna verses a Katana, This video is more evadence, you can hear the stall horn the entire time, Cessna's just for the first rotation then it enters a spiral.

Front. · Post by **Front.** » Fri Jul 21, 2006 1:31 pm

LOL!

i was just wondering though, how many G's do you lose in a spin? do you go to negatives... does it stay at 1, does it go up to 1.5? how will it be...

Redneck_pilot86 · Post by **Redneck_pilot86** » Fri Jul 21, 2006 1:59 pm

1G the whole time, if its done right...one of my instructors placed the fuel strainer cup on the dash to prove it to me....it never wiggled through the entry, 4 rotations and recovery. Lotsa fun...spins are the only thing i miss about flying on wheels.

ST

Blue Side Down · Post by **Blue Side Down** » Fri Jul 21, 2006 9:47 pm

Just to add a bit of kindling to the quiet fire here...

I think that the issue may have less to do with 'overall weight' limitiations, and more to do with Center of Gravity complications.

An aircraft is designed such that it's wings can handle what... 3.5 *(1.5) (factor of safety)= 5.25 times its certified gross weight... no? So say you take a fully loaded aircraft (small aircraft for the sake of this argument)- in theory, and practice, you could load the wings such that you're sustaining 3.5 g's, at any given airspeed under Vne, and nothing important will break. Granted, this is not reccommended. Anything to disagree with so far?

That being said, so long as you know how much enthusiasm you can pull out of the ensuing dive with, you will not hurt an airplane by spinning it at gross weight by exceeding airspeed/ structural limitations.

The more important issue may be that once you fill the sucker full of gas, and two/ four people, you now have a 'rearward' C of G. This is going to be a problem (and has been a problem in the past); and likely has been the cause of more than a handful of unrecoverable spin accidents.

A rearward C of G will allow the spin to flatten easier/ without pilot input/ right quick... Then once the said spin goes flat, there may be nothing that the pilot can do with the controls that will 'unflatten' the spin and bring it (back) to a stage from which recovery is possible. Then the pilot and crew go round-and- round all the way down, befuddled about what strange thing this plane is doing now.

...just a thought...

...I wonder if this is the instructor's reason for not doing fully loaded spins?

Front. · Post by **Front.** » Fri Jul 21, 2006 10:44 pm

oh okey cool...

mellow_pilot · Post by **mellow_pilot** » Sat Jul 22, 2006 12:32 am

Spin recoveries, depending on the type of plane, may require a fair amount of input to complete. You are likely to 'pull Gs' when exiting the dive subsequent to the recovery of teh aircraft from the spin, but as mentioned previously, the actual spin is a 1 G manouver. (although depending on the aggressiveness of entry and type again, it may or may not load or unload a bit) In general, Cessnas are pretty docile in a spin, other types like Katanas can be more aggressive.

Spins and spirals are nothing to fret about. Simply give the manouvre the respect it is due. For your first souple of times, it may be a good idea to hold on to something like a door handle or seat belt to keep your hands away from the controls, atleast until you are used to the feeling. Either way, if you are concerned talk to your instructor about it, no sense surprising them or yourself inflight.

Spins are one of my favourite things to do with an airplane, enjoy!

fougapilot · Post by **fougapilot** » Sat Jul 22, 2006 3:41 am

It has been a long time since I flew an airplane with both Normal and Utility categories in its W&B data. My work airplane only has a Normal category and my play airplane only has an aerobatic category, but if my memory serves me right the Utility category was limited in both CofG location and weight.

No doupt the CofG affects the spin caracteristics of an airplane. Being at the forward CofG limit on my CJ make the thing nearly spin proof. If I want to spin the thing, I really have to work it.

One thing we must not forget is metal fatigue. Metal has a memory. You can bend it once to its ultimate limit or 1 000 000 times to 10% of its limit and the result is the same; it will break. Pulling the G limit on a fully loaded aircraft will use more life out of the metal than pulling it 50% loaded (3.5G at 2000lbs = 7000lbs Vs 3.5Gs at 1000lbs = 3500lbs).

This is the same reasons larger aircrafts have maximum landing weight. My CL601 has a maximum landing weight of 36 000lbs. Can I land at a higher weight? You bet your sweet ass I can. If I loose an engine on take off at 45 100lbs, I will retun and land. No wasting time burning fuel. There is a provision in the maintenance manual for inspections after an overweight landing. But if I make every landing at 45 100lbs... maybe the gear wont last that long...

The same is true for spar and wing attachements. If you stay within the Utility category for all your spins and spirals then you won't take too much life out of them. But if you start spinning the thing fully loaded, who knows? Just look at the T34 accidents in the USA. So far there has been 3 wing seperation in flight. On airplanes that are aerobatic certified, designed for the millitary. But after 15 000hrs of abuse, the wings attachments just ran out of live.

How many basic training airplanes out there with 10 000+ hrs? I know a few. Even see guys spinning a Buck fifty with more then 15 000hrs TTSN...

D

C-GPFG · Post by **C-GPFG** » Fri Jul 28, 2006 10:25 am

niss wrote:What kind of experience did you guys have putting a Cherokee 140 into a spin? Is it tough to do?

Not a problem.. usually would spin without power. They were a little sluggish coming out of the spin.

There was an advisory out about 6 years ago regarding PA28-140 spins. I think it had something to do with recovering after one or two rotations and by 3,000 AGL due to flat spin fatal accidents.

C-GPFG · Post by **C-GPFG** » Fri Jul 28, 2006 10:29 am

found the alert...

http://www.tc.gc.ca/CivilAviation/certi ... 998-01.htm

. ._ · Post by **. ._** » Fri Jul 28, 2006 11:46 am

Here's my favourite spin vid. It's an excerpt from a larger movie, so the music is a little choppy.

It's an anonymous Sault College student.

http://s64.photobucket.com/albums/h169/ ... t=spin.flv

-istp

Lommer · Post by **Lommer** » Fri Jul 28, 2006 4:22 pm

nice vid - i counted 7 rotations. Is it just me or does the guy look like he's about to puke halfway through the spin?

. ._ · Post by **. ._** » Fri Jul 28, 2006 5:03 pm

I don't think it was 7 rotations. About 5 and a half, IMHO. Hard to tell.

The guy is super serious when he flies, and really doesn't like spins too much, but no, he never came close to hurling on that flight.

He's a very good pilot and friend of mine, so I'd know, you see.

-istp

Norskman · Post by **Norskman** » Mon Aug 07, 2006 2:06 pm

I still remember one of the times my instructor asked me to do a stall, and for some reason, I thought that he had said spin. Of course since they both start the same way (power off spin/stall), he didn't have a clue what was going on till I trounced the rudder and controls. I think its one of the very few times he swore

767 · Post by **767** » Tue Aug 08, 2006 11:27 am

Hey can someone tell me if we have to demonstrate spins/spirals during TC flight test(s)??