Approved aerobatics in MiniNimbus

[Van Henson]

Hey Ho-

I'm interested in whether someone can interpret my POH for me. I have MiniNimbus B and the POH says,

***
The Mini-Nimbus B is approved for the following acrobatic maneuvers:

Maneuver Entry Speed (kts)
Inside Loops 108
Spins 32
Turns 108
Lazy Eight 97
***


Does anybody know what they mean by "Turns"? I'm guessing they don't mean a gentle 90-degree turn to the right or left...

[QRP Nimbus C]

On Thursday, March 12, 2015 at 3:13:56 PM UTC-7, Van Henson wrote:
> Hey Ho-
>
> I'm interested in whether someone can interpret my POH for me. I have MiniNimbus B and the POH says,
>
> ***
> The Mini-Nimbus B is approved for the following acrobatic maneuvers:
>
> Maneuver Entry Speed (kts)
> Inside Loops 108
> Spins 32
> Turns 108
> Lazy Eight 97
> ***
>
>
> Does anybody know what they mean by "Turns"? I'm guessing they don't mean a gentle 90-degree turn to the right or left...

My Mini Nimbus "C" ser#102 manual pg 36 says:

"TURNS, flaps in position -7 deg. Entry to the turn at speeds not less than 97 Kts. A speed of 108 Kts. is recommended. After entry to the turn apply rudder in the vertical climb at a speed of 70 Kts. Speed during recovery from the turn: 97-108 Kts."

Sounds like "in the vertical climb" implies a hammerhead stall to me ! Speed is probably dropping off precipitously at 70 Kts. in the vertical and if allowed to proceed beyond that before kicking in rudder, you are probably looking at a tail slide. Don't know what level of damage might or might not occur to the tail feathers in that case, so I'd err on the side of caution kicking in the rudder !! One other thing, since the rudder is asymmetrically mounted, kicking in the rudder in one direction is immenently more effective than the other. In my "C", I'd be using right rudder.

[kirk.stant]

On Thursday, March 12, 2015 at 7:30:43 PM UTC-5, QRP Nimbus C wrote:
> On Thursday, March 12, 2015 at 3:13:56 PM UTC-7, Van Henson wrote:
> > Hey Ho-
> >
> > I'm interested in whether someone can interpret my POH for me. I have MiniNimbus B and the POH says,
> >
> > ***
> > The Mini-Nimbus B is approved for the following acrobatic maneuvers:
> >
> > Maneuver Entry Speed (kts)
> > Inside Loops 108
> > Spins 32
> > Turns 108
> > Lazy Eight 97
> > ***
> >
> >
> > Does anybody know what they mean by "Turns"? I'm guessing they don't mean a gentle 90-degree turn to the right or left...
>
> My Mini Nimbus "C" ser#102 manual pg 36 says:
>
> "TURNS, flaps in position -7 deg. Entry to the turn at speeds not less than 97 Kts. A speed of 108 Kts. is recommended. After entry to the turn apply rudder in the vertical climb at a speed of 70 Kts. Speed during recovery from the turn: 97-108 Kts."
>
> Sounds like "in the vertical climb" implies a hammerhead stall to me ! Speed is probably dropping off precipitously at 70 Kts. in the vertical and if allowed to proceed beyond that before kicking in rudder, you are probably looking at a tail slide. Don't know what level of damage might or might not occur to the tail feathers in that case, so I'd err on the side of caution kicking in the rudder !! One other thing, since the rudder is asymmetrically mounted, kicking in the rudder in one direction is immenently more effective than the other. In my "C", I'd be using right rudder.

In Europe, a "Stall Turn" means a hammerhead turn. The Stall probably got lost in the translation. Look at any ASK-21 manual and it will make sense.

Hammerheads/stall turns are a lot of fun in a glider if done right - but can get hairy if not done right! Please get some acro training in a K-21 or G-103 Acro before trying this on your own.

But I sure wish my LS6 was approved for stall turns!

Kirk
66

[[email protected]]

In my basic (powered) aerobatics rating, a stall turn was an inertial/vertical climb where at the minimum speed possible, full rudder was used to yaw the aircraft to a nose-down attitude. Sufficient opposite aileron was used to prevent roll and ensure exit was in the same plane/direction as entry.

A hammerhead was a tail slide. Same entry as above but no application of rudder nor aileron. Controls locked to minimise damage when you start to fly backwards and after a time, the aircraft 'self corrects' and flicks to a nose down attitude.

Both highly enjoyable in their own right but unless being flown intentionally, the latter is a consequence of the mis-flown former. I'd never attempt to hammerhead/tail slide a glider due to the resultant stress on the control surfaces unless it was specifically built for that purpose, ie the fully aerobatic ships.

Given your description, I share Kirks perspective that it's a 'stall turn' that's been lost in translation.

CJ

[Gliding Guru]

>
>But I sure wish my LS6 was approved for stall turns!
>
>Kirk
>66
>
>

LS6 may not be "rated" but is a great aerobatic glider. Have seen a number
of displays in France with hesitation rolls and inverted fly pasts. -

[kirk.stant]

On Friday, March 13, 2015 at 5:30:08 AM UTC-5, Gliding Guru wrote:

> LS6 may not be "rated" but is a great aerobatic glider. Have seen a number
> of displays in France with hesitation rolls and inverted fly pasts. -

Well I do know of one that is looped and barrel rolled occasionally, which it does quite nicely ;^)

Funny about aviation terminology. "Stall Turn" makes no sense, as during a Hammerhead the wing is never stalled (never reaches stalling AOA), and a real stall turn is a spin entry!

I was taught 4 ways to correctly exit a vertical climb: Hammerhead left or right, and Tailslide forward or backwards. Hammerheads properly done are slow and majestic, Tailslides are fast and almost violent. All are fun, done properly.

Of course, there is a fifth way - usually caused by waiting too late to push in full rudder. A bit terrifying the first time, but more of a source of giggles and cuss words after that.

Of course, we have the never ending argument over "forward slips" and "side slips".

And for the unwashed masses, there is the notorious "Tail Spin", followed invariably by a fatal "Nose Dive" (which invariably occur, in power planes, after the engine "stalls"). Which begs the question: Can you "Nose Spin" into a "Tail Glide"? Perhaps a Youtube search is called for!

Kirk
66

[Dan Marotta]

I performed many loops, rolls, and whifferdills in my LS-6a but nothing
more energetic than those. Always a delight to fly!

On 3/13/2015 4:20 AM, Gliding Guru wrote:
>> But I sure wish my LS6 was approved for stall turns!
>>
>> Kirk
>> 66
>>
>>
> LS6 may not be "rated" but is a great aerobatic glider. Have seen a number
> of displays in France with hesitation rolls and inverted fly pasts. -
>

--
Dan Marotta