2 Killed In Motorglider

[youngbl...@gmail.com]

Japan, two killed as the Arcus crashed into a shallow river north of Tokyo. I just say the photographs of the Arcus and was a bit surprised at the fatalities . OBTP

[youngbl...@gmail.com]

On Wednesday, October 13, 2021 at 7:37:22 PM UTC-4, youngbl...@gmail.com wrote:
> Japan, two killed as the Arcus crashed into a shallow river north of Tokyo. I just say the photographs of the Arcus and was a bit surprised at the fatalities . OBTP

saw the photos, sorry for the big fingers.

[Herbert Kilian]

Everybody following aviation and soaring news knows about that already, why put it into a post? To support your strange opinion on motor-gliders?

[youngbl...@gmail.com]

Herbert, the tragic loss of two glider pilots has nothing to do with any opinion that I have on motorgliders. As you stated that everyone following aviation already knew about the incident, yet there was nothing posted on this group. Maybe you know something that some of us others do not, try not being so pompous, you will look a lot better. Old Bob, The Purist

[Dan Marotta]

Well, this is the first I've heard of it.  That's three Arcus crashes
I'm now aware of, out of how many built?

Thanks for posting, Bob.

Dan
5J

[Mike Carris]

On Wednesday, October 13, 2021 at 9:56:38 PM UTC-6, Dan Marotta wrote:
> Well, this is the first I've heard of it. That's three Arcus crashes
> I'm now aware of, out of how many built?
>
> Thanks for posting, Bob.
>
> Dan
> 5J

What Dan said.

[Bob W.]

>>> Japan, two killed as the Arcus crashed into a shallow river north

>>> of Tokyo. I just sa[w] the photographs of the Arcus and was a bit
>>> surprised at the fatalities. <Snip...>

> Everybody following aviation and soaring news knows about that
> already, why put it into a post?

News to me, & I try to "remain up" on aviation crunches...

Bob W.

[Martin Gregorie]

Like almost everybody else, Bob's post is the first I've heard of this
crash. Here's a link to the rather uninformative article and the
aforementioned photos:

https://fl360aero.com/detail/a-schempp-hirth-arcus-m-motor-glider-crashed-
into-a-river-near-biei-town-hokkaido-japan-on-a-training-flight-killing-
two/726


--
--
Martin | martin at
Gregorie | gregorie dot org

[andy l]

You mean altogether, or this year?

Before this one, the most recent happened from being waved off at about treetop height, when the tug had an engine problem.

Ironically, this was a self-launching glider, but the pilot had decided an aerotow would be more agreeable for the guest passenger.

.

[andy l]

To clarify, my last paragraph is about the previous one, not the one in Japan

[kinsell]

There was one that crashed into a tree near Bicester England, but that
was an Arcus T, not a self launcher. Pilot not injured.

[R]

I believe it to be a problem with the Indians and not the Arrows.
R

[AS]

You are correct, Martin - the article is very uninformative!
Looking at the pictures raises a number of questions. The cockpit area seems mostly intact, so how did the two occupants loose their lives? Did the glider crash into the deeper part of the river and they drowned?

Uli
'AS'

[waremark]

How tragic.

I've looked at Google Translate versions of a few articles. It sounds as though the engine failed shortly after take-off (reports all say 80m to 100m - which I would expect to be high enough for a turn back), and that there was subsequently a stall-spin. Apparently the two pilots in their sixties were experienced, but it was the third flight of a brand new Arcus M.

Incidentally, I have practised in my Arcus M at altitude turning back immediately after engine switch-off and neither handling nor height loss is alarming. From 300 foot I would expect to be able to turn back and land downwind (all the reports say the wind was very light and weather conditions good).

From reports on Yahoo Japan:

"an air accident investigator from the national transportation safety board investigated the aircraft on wednesday. he expressed the view that it was believed to have crashed southward after taking off north and turning above."

and

"A MAN WHO MET THE TWO MEN SAID, "WITHIN A MINUTE OF TAKING OFF, THEY FELL SPINNING FROM AN ALTITUDE OF ABOUT 100 METERS, BOTH OF WHICH WERE GLIDERS AND VETERANS WITH A LONG HISTORY OF PILOTING."

[2G]

The loss of your only engine shortly after takeoff is undesirable and an emergency for ANY aircraft, not just motorgliders. Motorgliders, at least, have a very good possibility of completing the "impossible turn" and safely returning to the airport, unlike, say, a Pawnee. Once while taking a lesson in a C152 the instructor "failed" the engine shortly after takeoff. We were probably 800-1000 ft AGL and I had already done a left departure turn of 70-80 degrees. I immediately pushed the nose down and did an aggressive left turn back to the airport and flew the best glide speed back towards the end of the runway. We made the runway, but not with a lot of margin - if I was heading straight out there is no way I could have completed a successful return to the airport. In fact, a couple of guys we doing touch and goes at the same airport also in a C152 when the engine died due to fuel exhaustion. The pilot tried to make the turn back, stalled the aircraft sending into a short spiral dive. They impacted vertically and were killed. This was one of the best lessons I had during my power training. This FAA article discusses the impossible turn:
https://www.faasafety.gov/files/gslac/library/documents/2018/Nov/164492/P-8740-44.pdf
Motorgliders, however, will not sink at 1000 fpm, but more like 150-200 fpm with the prop extended, so they can complete the turn at 300 ft - if done PROPERLY! The pilot in the accident glider did not execute the turn properly, stalling the glider instead. At that altitude there is NO possibility of recovery and a fatal crash is inevitable. Also, when the engine stops in motorglider with the prop on a mast there is a pitch-up due to the loss of thrust from the prop. This is easily corrected by a modest forward stick, but the pilot here may not have done that, which would have set him up for a stall-spin.

Here is a link that provides a number of links to articles on the accident:
https://aviation-safety.net/wikibase/268487

Tom

[kinsell]

Here's a list, may not have all losses. Unfortunately, doesn't strike
me as being out of line with other motorgliders:

http://www.rcawsey.co.uk/Arcus.htm

There was one in France that had an aborted takeoff, brake overheated
and burned the glider completely before they could put it out. Not a
crash, but an interesting way to lose a glider.

https://www.bea.aero/en/investigation-reports/notified-events/detail/accident-to-the-schempp-hirth-arcus-m-registered-d-kkoy-on-30-07-2019-at-sisteron-theze-aerodrome/

[Mark Mocho]

The Arcus M Pilot Operating Handbook states that the sink rate with the engine extended but not running is 492 fpm at 60 knots.

[2G]

On Thursday, October 14, 2021 at 7:51:48 PM UTC-7, Mark Mocho wrote:
> The Arcus M Pilot Operating Handbook states that the sink rate with the engine extended but not running is 492 fpm at 60 knots.

I can complete a 360° turn in under 30 sec. So I should be able to complete 225° in 19 sec. At that sink rate the total altitude loss will be 157 ft. Add another 4 sec and the loss is 187 ft. They must have been near the end of the runway at 300 ft, so they could have made it.

Tom

[jfitch]

If the sink rate straight ahead is 492, the sink rate in a steep banked turn will be considerably higher. So not a sure thing. Sounds like they tried, but entered a spin trying.

[Ramy]

A similar situation happened at Hollister 3 days earlier on Saturday but ended well. DG800 engine quit at 400 ft AGL, the pilot reacted quickly, pushed the nose down, did 180 and landed back on the runway. Lost about 200 feet making the turn. The trace is on OLC.

Ramy

[waremark]

As I mentioned above, in my Arcus M I have tried at altitude switching off, lowering the nose to maintain a safe speed, and turning 180 degrees. My actual height loss was much less than 300 feet and it left me deciding that if I had an engine failure after take-off at 300 foot (or more) I would definitely turn back and expect to be able to make a safe downwind landing. I will try this again next season. I cannot quite reconcile my experience to the POH sink rate figure of 492 fpm.

My normal practice is to commence a turn shortly after take-off and to run downwind alongside the airfield. Therefore from the time it feels safe to turn until I am at a good height I am in a comfortable position to drop back into the airfield if the engine stops.

The worst I have had happen to me in 15 years of flying a self launcher was a belt break just after lifting off, with plenty of space to land and stop ahead. The touchdown, from a low speed and with the drag of the extended and not turning prop, was rather heavy, but not damagingly so. Since then, I try to hold the glider down for a moment after lift off until a safer speed is achieved.

Mark Burton, UK based Arcus M owner

[jfitch]

Another variable here is the 300 ft. This is an off hand estimate by some unknown witness, reported in a vague new story, not somebody standing there on a ladder with a long measuring tape. Could easily have been 200 ft or less.

[2G]

I, also, don't buy that 492 fpm figure. Every time I launch I must shut down the engine and retract the prop on my 31Mi. It takes a little while to align the prop, and then it is 13 sec to retract it. This kind of sink rate would show up on my flight log and it doesn't. One time I tried doing a sink rate test with the prop extended. The sink rate, of course, went up, but maybe 100 to 150 fpm (the air just wasn't calm enough to do a good glide test, so I aborted it). I looked up the flight logs of an Arcus M and saw pretty much the same thing (https://www.onlinecontest.org/olc-3.0/gliding/flightbook.html?sp=2021&st=olcp&rt=olc&pi=50224).

Tom

[John Galloway]

My Ventus-3M manual gives 453fpm with the engine out and stopped. That figure will not have been plucked out of thin air by Schempp-Hirth; rather it will be the result of proper testing during the certification flights. I will continue to make my eventuality plans around it.

[Eric Greenwell]

On 10/16/2021 8:36 AM, John Galloway wrote:
> On Saturday, 16 October 2021 at 00:36:24 UTC+1, 2G wrote:

...

>>>>>> On Thursday, October 14, 2021 at 7:51:48 PM UTC-7, Mark Mocho wrote:
>>>>>>> The Arcus M Pilot Operating Handbook states that the sink rate with the engine extended but not running is 492 fpm at 60 knots.
>>>>>> I can complete a 360° turn in under 30 sec. So I should be able to complete 225° in 19 sec. At that sink rate the total altitude loss will be 157 ft. Add another 4 sec and the loss is 187 ft. They must have been near the end of the runway at 300 ft, so they could have made it.
>>>>>>
>>>>>> Tom
>> I, also, don't buy that 492 fpm figure. Every time I launch I must shut down the engine and retract the prop on my 31Mi. It takes a little while to align the prop, and then it is 13 sec to retract it. This kind of sink rate would show up on my flight log and it doesn't. One time I tried doing a sink rate test with the prop extended. The sink rate, of course, went up, but maybe 100 to 150 fpm (the air just wasn't calm enough to do a good glide test, so I aborted it). I looked up the flight logs of an Arcus M and saw pretty much the same thing (https://www.onlinecontest.org/olc-3.0/gliding/flightbook.html?sp=2021&st=olcp&rt=olc&pi=50224).
>>
>> Tom
>
> My Ventus-3M manual gives 453fpm with the engine out and stopped. That figure will not have been plucked out of thin air by Schempp-Hirth; rather it will be the result of proper testing during the certification flights. I will continue to make my eventuality plans around it.
>

Try some in-flight testing at a thousand+ feet AGL, where you are in a full power climb,
then shut off the motor. You may be delightfully surprised at how little altitude you lose
in a 180 degree turn. I did that several times with my ASH26E, and it was about 100 feet,
so I am confident I can do it in an emergency above 200' AGL. I believe a real-life test
like this is much more useful than a manual number.

A simpler test in smooth air: extend the gear and the engine, and note the sink rate. You
can even do it in the pattern, or on the way to the pattern. My experience is that result
is the same as Tom's - hardly noticeable.

Seriously, every flight I thermal for 3+ minutes with the mast partially retracted to
about 30-40 degrees above horizontal while the engine is cooling. Putting it away hardly
affects my climb rate. Maybe Schleicher gliders have superior mast extended performance
over the "other guys"?

--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications/download-the-guide-1

[BG]

We instictively

[BG]

We instinctively grab and pull the spoilers when we land, landing with the engine out, this could kill you

Buzz

[John Galloway]

I flew an ASH26e for two years before the V3M and I agree with the flight manual estimate of 20:1 glide ratio for the ASH26e (i..e roughly equivalent to 300fpm sink rate) which is a bit better than the V3M and Arcus M. With regard to owner/pilots own figures I do not "believe a real-life test like this is much more useful than a manual number". Even if they were possible at altitude in a relaxed manner than to bet one's life on always being able to emulate it at low altitude under the stress of an emergency seems unwise to me.

[Eric Greenwell]

I do not "instinctively grab and pull the spoilers when" I land; using them is part of the
plan to land. It's also part of my plan for an emergency landing, because I will almost
surely need them after doing the 180 back to the runway. In my 26E, the pylon out is like
just cracking spoilers, and full spoiler with the mast out does not make the glider
uncontrollable or impossible to flare. My normal landings are with the 40 degree landing
flap, which allows an ever steeper glide path, and I have done landings with the mast out.
It's easy.

I suggest any pilot with concerns about his ability to manage a landing with the mast
should practice doing that until comfortable. It's a non-event, as you simply use a bit
less spoiler than you normally do for a landing.

[Eric Greenwell]

On 10/16/2021 11:41 AM, John Galloway wrote:
> On Saturday, 16 October 2021 at 17:10:07 UTC+1, Eric Greenwell wrote:
>> On 10/16/2021 8:36 AM, John Galloway wrote:
>>> On Saturday, 16 October 2021 at 00:36:24 UTC+1, 2G wrote:
>> ...
>>>>>>>> On Thursday, October 14, 2021 at 7:51:48 PM UTC-7, Mark Mocho wrote:
>>>>>>>>> The Arcus M Pilot Operating Handbook states that the sink rate with the engine extended but not running is 492 fpm at 60 knots.
>>>>>>>> I can complete a 360° turn in under 30 sec. So I should be able to complete 225° in 19 sec. At that sink rate the total altitude loss will be 157 ft. Add another 4 sec and the loss is 187 ft. They must have been near the end of the runway at 300 ft, so they could have made it.
>>>>>>>>
>>>>>>>> Tom
>>>> I, also, don't buy that 492 fpm figure. Every time I launch I must shut down the engine and retract the prop on my 31Mi. It takes a little while to align the prop, and then it is 13 sec to retract it. This kind of sink rate would show up on my flight log and it doesn't. One time I tried doing a sink rate test with the prop extended. The sink rate, of course, went up, but maybe 100 to 150 fpm (the air just wasn't calm enough to do a good glide test, so I aborted it). I looked up the flight logs of an Arcus M and saw pretty much the same thing (https://www.onlinecontest.org/olc-3.0/gliding/flightbook.html?sp=2021&st=olcp&rt=olc&pi=50224).
>>>>
>>>> Tom
>>>
>>> My Ventus-3M manual gives 453fpm with the engine out and stopped. That figure will not have been plucked out of thin air by Schempp-Hirth; rather it will be the result of proper testing during the certification flights. I will continue to make my eventuality plans around it.
>>>
>> Try some in-flight testing at a thousand+ feet AGL, where you are in a full power climb,
>> then shut off the motor. You may be delightfully surprised at how little altitude you lose
>> in a 180 degree turn. I did that several times with my ASH26E, and it was about 100 feet,
>> so I am confident I can do it in an emergency above 200' AGL. I believe a real-life test
>> like this is much more useful than a manual number.
>>
>> A simpler test in smooth air: extend the gear and the engine, and note the sink rate. You
>> can even do it in the pattern, or on the way to the pattern. My experience is that result
>> is the same as Tom's - hardly noticeable.
>>
>> Seriously, every flight I thermal for 3+ minutes with the mast partially retracted to
>> about 30-40 degrees above horizontal while the engine is cooling. Putting it away hardly
>> affects my climb rate. Maybe Schleicher gliders have superior mast extended performance
>> over the "other guys"?
>>

>> Eric Greenwell - USA

> I flew an ASH26e for two years before the V3M and I agree with the flight manual estimate of 20:1 glide ratio for the ASH26e (i..e roughly equivalent to 300fpm sink rate) which is a bit better than the V3M and Arcus M. With regard to owner/pilots own figures I do not "believe a real-life test like this is much more useful than a manual number". Even if they were possible at altitude in a relaxed manner than to bet one's life on always being able to emulate it at low altitude under the stress of an emergency seems unwise to me.

Using a sink rate number that is too high does not always give you a better safety margin,
if it causes you to accept a straight ahead landing into unsafe terrain (rocks, trees,
fences, whatever) instead of turning back. It's easy to do, takes only a few minutes, so
consider it practice, and the bonus is it gives you a check on the numbers you are using.

[Eric Greenwell]

That "superior mast extended performance" might actually be true: The SH gliders, like the
Arcus M, have a very "fat" (wide chord) propeller blade, while the Schleicher gliders have
a very skinny blade, so maybe Arcus/Ventus motorgliders really do have a "plummet mode",
compared to the ASH26E, 31Mi, etc.

So, someone, somewhere, coasting home with his SH motorglider in the still evening air,
should extend the mast and gear for a couple minutes (or longer) at 60 knots. We can
examine the IGC file for a good indication of the sink rate.

[2G]

Using a number that is too high could cause you to do something that is unsafe (crashing into trees instead of landing on a runway) - you need to use, and trust, realistic numbers. I remembered a real-world situation (not a test) that happened to me six years ago flying my ASH26e out of Ely, NV. I had to do a restart after everything I could reach died. I started the restart at a pretty high altitude (3,900 ft AGL) because the next lift looked too far away to reach. I just flew over a pretty good looking set of fields and had another landable strip in my database, so I wasn't particularly concerned, especially considering the reliability of Schleicher motorgliders. So I turned on the ILEC (engine controller) and flipped up the prop extend switch and released the prop brake (bad move!). I was enjoying the view when I realized that I hadn't gotten the prop extend green light. I checked the mirror and, to my horror, the prop wasn't moving! I cycled the prop by retracting it partway and extended it again. Same result. So I tried that a second time and, again, got the same result. I thought that maybe I could start the engine anyway so I turned on the ignition - the ILEC started flashing a lot of red lights so I knew that wasn't going to happen. At this point I knew I had a serious problem and immediately executed a 180° turn to head back towards the fields I had over-flown. Then, when I thought things couldn't get any worse, the circuit breaker popped on the ILEC! Now I couldn't retract the prop! At this point I am looking at doing my first out-landing in 13 years into a field that is about as remote as you can get in the US. I still had plenty of altitude, but not enough to reach the airstrip in my database with the prop extended. I did the only thing left to me (besides preparing for an out-landing): I kept pushing the circuit breaker. After what seemed like an eternity (in reality it was only about 3 min) the circuit break reset and, miracle of miracles, I got the green light! I flipped on the ignition, started the engine, and got the hell out of dodge. I found a thermal a few miles away, shut down the engine and soared back to Ely. After getting back I tried multiple extensions and restarts and it worked every time. I think that initially I was flying a bit too fast for the prop to extend that last little bit to activate the microswitch. After making the turn I slowed down, allowing the prop to fully extend and activate the microswitch.

What this experience gave me is an actual flight log of a real (not simulated) engine failure condition. The prop was extended and the engine wasn't running when I did a 180° turn and glided over 4 km. The air was pretty smooth during the entire event. This flight log is available for all to see at:
https://www.onlinecontest.org/olc-3.0/gliding/flightinfo.html?dsId=4554327
The IGC file can be downloaded if you have an OLC account. Here are the critical points in the flight:

Start of turn = 22:53:03 2977m MSL
Mid-point of turn = 22:53:17 2971m MSL
Finish of turn = 22:53:40 2936m MSL
Engine start = 22:56:03 2754m MSL

The altitude lost in making the 180° turn was 41m (135 ft) and the turn took 37 sec to complete (this is not particularly accurate because the recording interval was 5 sec, but it gives you data that is within 14%, so the altitude lost could be as much as 153 ft).

OLC actually counted my last leg as the turn mid-point to the engine start! The distance of this leg was 4.35km. But to get a more accurate measurement of glider I determined the distance from the end of the turn to engine start using the GPS coordinants and got this result:

Prop extended glide distance = 3.88 km
Time = 222 sec
L/D = 21.3
Descent rate = 0.82 mps (161.4 fpm)

This result closely matches Eric's L/D figure of 20. I could not find a similar specification for my ASH31Mi. I welcome anyone else reading this to check my math.

Again, these claimed sink rates for the Arcus M should readily apparent in the flight logs, and I am not seeing it. It definitely didn't show up in my real-world situation.

Operationally, there is a simple thing you can do to improve your odds of making the turn back to the runway: after rotating slide over so that you are parallel to the runway such that in the event of an engine failure you only have to make a 180° instead of a 225° turn.

Tom

[waremark]

On Saturday, 16 October 2021 at 22:12:57 UTC+1, 2G wrote:
>
> Operationally, there is a simple thing you can do to improve your odds of making the turn back to the runway: after rotating slide over so that you are parallel to the runway such that in the event of an engine failure you only have to make a 180° instead of a 225° turn.
>
> Tom

Yes, and I think Eric included something like that in his brilliant guide to SLMG operation, but I wouldn't want to leave the runway line while there is still space to land ahead on the runway.

[2G]

I agree that if you can still land straight ahead you stay over the runway, but after passing this point moving sideways is a good idea.

Tom

[Eric Greenwell]

There is an advantage to moving off the runway center line, even before there isn't enough
remaining runway to land ahead: You keep the runway in sight, and can better judge when
you can't make it anymore. Typically, I veer off about 30-40 degrees from the runway as
soon as I've established a steady climb after lifting off; after I have enough distance to
make a 180 back to the runway, I'll turn to parallel it.

[youngbl...@gmail.com]

Eric, this is getting a bit crazy, so many experts that opine on something that they know very little about. Even Kingfish with all his POH numbers has no idea as to the reality of a crisis in the cockpit. I hear all these so called professional opinions say this and that. Oh, what about I can make that turn in 19 seconds, give me a break.
The reality of this and other crisis situations is situational awareness, just how long does it take to identify, verify and react to any emergency situation can be the difference between life and death. Hypothetical analysis is like Monday morning quarterbacks, maybe Herbert can tell us more. Old Bob , The Purist.

[andy l]

That sounds more realistic than some of the folk here trying to negotiate with each other who can lose the least height

Nearly 40 years ago there was a fatal spin in at our club when a motor glider tried turning after apparent engine failure at about 300 feet.

I'm not a motor glider pilot, but we are all used to considering what happens if ... Passing the other end of the airfield at whatever typical height on aerotow and thinking about it from there isn't necessarily realistic for a case when the tug will have a problem, as we were reminded not long ago.

Surely the same applies to a motor glider flight, that whatever the mental rehearsals you have, with or without calculations as above, it isn't necessarily going to be just like that, the decisions might not be triggered by power suddenly going from 100% to 0, you can have less and be unfamiliarly low

Whatever, we are told these pilots in Japan were experienced. They'd have thought about some of this in advance too.

On Sunday, 17 October 2021 at 00:49:16 UTC+1, jonatha...@gmail.com wrote:
> Standard warning, I know nothing. However, I have heard pilots, mention things like the startle effect, which could take a few seconds to react, and I seem to remember somewhere that the atmosphere is dynamic. As I understand, that means air could be sinking which might have an effect on the altitude used in a 180 turn. I know one pilot that thought they would fly under a cell, over West Guard Pass at 15,000 feet, it looked friendly enough, and his 44/1 glider barely, and I mean barely made Bishop airport 4,400 ft and 8 miles. Could be they thought they had a fire and put it in the water... we just do not know. We can keep guessing though.

[2G]

Hey Racist Bobby, I have experienced multiple engine failures on takeoff in a motorglider - how many have YOU experienced? I expect the number to be exactly ZERO (I seriously doubt that you have even flown a motorglider)!

Tom

[2G]

Andy,

I have actually been thru multiple engine failures due to various causes and can tell you that you plan for the emergency and, then if the emergency arises, execute the plan. This also happened to me in my power training when the instructor "failed" the engine - I did not hesitate in the slightest to do what was necessary. And, no, the instructor never warned me that he might "fail" the engine. If you think like Racist Bobby thinks, and doubt your abilities, it would not surprise me at all that, if the need arose, you would freeze or do the wrong thing. Think Colgan Air crash.

Tom

[youngbl...@gmail.com]

Andy, most of the so called professional replies in this thread have been based on assumption and speculation little thought has been given to the situation as in such tragic events. I really chuckled at the reply from Kingfish where he stated that his instructor pulled the power back to simulate engine failure, but having a real and not simulated emergency and reacting is a different situation.

[andy l]

I broadly agree with that, but some of the above discussion is bordering on boasts about who can lose the least height in a turn, or timings to the nearest second. That precision might not apply if the glider is at 80 feet in a position where it is usually at 150 to 200 feet, due to underperforming tug or glider engine, and thinking about that too should be part of a plan, that's what I was trying to say

[Martin Gregorie]

On Sat, 16 Oct 2021 16:49:14 -0700 (PDT), Jonathan St. Cloud wrote:

> Could be they thought they had a fire and put it in the water...
> we just do not know. We can keep guessing though.
>

"Putting it in the water" doesn't seem likely because the two photos that
give a good look at the front of the fuselage just show a shattered mess.
I'd expect stall/spin into shallow water to do that sort of damage.


--

Martin | martin at
Gregorie | gregorie dot org

[Eric Greenwell]

Standard training teaches the pilot, whether towed or self-launched, to have a plan for
most situations, including the ones you mention. These plans have to be based on what the
glider and pilot can do, and knowing the minimum height to make a return to the runway is
a critical one. There is no "precision" quibbling between 80', 200', and 300': those are
stark differences in altitude that make the difference between choosing landing ahead or
turning around, and that is why some of us are encouraging pilots to practice - at
altitude - the 180 degree turn, so they know what it actually takes in their glider at the
elevation they are flying at. Once they know what is possible from their test flights,
they can factor in whatever additional height they think they need to safely accomplish
the turn in an actual emergency.

For most gliders in most situations, 80' will be too low to turn back, and 300' will be
enough. The in-between altitude for turning back is something the pilot needs to select
shortly before the launch. The safest altitude won't always be the same height.

[2G]

One thing readers here should do is to take advice from someone who has thousands of hours in motorgliders and is a former CFIG, and not someone who has NEVER flown a motorglider and has an irrational grudge against them.

Information on the Arcus M engine out and stopped sink rate can be gleaned from actual flight logs. To this end, I looked at Dick VanGrunsven's Arcus M flight logs. Dick's flight logs with the Arcus M provide some insight into what the sink rate is with the engine extended. I looked at his very first posted flight:
https://www.onlinecontest.org/olc-3.0/gliding/flightinfo.html?dsId=8294284
He shut down the engine (following a short cooling period) at 21:40:53. After about one minute the sink rate slows noticeably, which I take to be the point at which the engine is fully retracted. I downloaded the IGC file and computed the sink rate for the engine extended at 384 fpm for a 117 m altitude loss. The minute following engine retraction he lost 38 m, or a 125 fpm sink rate. Later, he was doing 360 turns in 30 sec, so a 180 turn in 15 sec is clearly possible, and 20 sec is realistic from recognition to execution. This puts the total altitude loss at 192 ft, which could be done at 300 ft.

The difference in sink rates between the Arcus M and the ASH26/31 is probably due to the fact that the engine provides greater drag since it is, at least partially, in the air stream and the 26/31 is fixed in the fuselage. I recommend that Arcus M owners do multiple flight tests of this to determine a safe altitude for this maneuver.

Tom

[2G]

A minor correction: the altitude lost in 20 sec should be 128 ft, not 192 ft. This is well less than the 300 ft available.

Tom

[youngbl...@gmail.com]

Kingfish, I am so impressed by your credentials, maybe you should take a chair on the NTSB. I am going to send you another book, about narcissism. Please pat yourself on the back tonight as you look into the mirror taking a pic of your logbook. Old Bob, The purist

[Martin Gregorie]

On Sun, 17 Oct 2021 16:16:56 -0700 (PDT), Jonathan St. Cloud wrote:

> I am sorry Martin, that was a tongue-in-cheek comment, because of all
> the rampant speculation, the quoting of sink rate in straight flight,
> and boosts about how fast they can do a 180 turn. It was out of place,
> especially since no one seemed to get the thrust of my comments.
>
No worries. I posted that last comment that because I'm somewhat
surprised that nobody else has commented on the smashed nose cone:
something I noticed as soon as I saw the photos - that and the prop mast
apparently folded back into the fuselage, which is not where I'd expect
to see it if the prop was still out at impact.

[John Galloway]

It is possible that they may have partially retracted the Arcus pylon irrespective of the prop position. I can't speak for the Arcus M flight manual but the V3M manual suggests that as a possibility by using the ""manual" override switch. I have done that, not because of low level engine failure but after a launch and engine shutdown when I couldn't get my prop centred using the either the auto or manual prop brake. It is on my own mental emergency procedure as my left hand wouldn't be needed for anything else until or unless I needed to use the airbrakes. Possible minor damage to the prop or engine doors would be the least of my concerns.

[2G]

Partially retracting the prop/engine (forgoing the alignment necessary to fully retract the prop) makes sense to reduce the drag of the stopped prop. Of course the pilot is very busy at this time and has other things to worry about (flying the glider, radio communication, fuel shutoff, etc.) and it would be understandable if he/she did not do that. It would be helpful to measure the drag of the partially extended prop to know what difference it makes.

Tom

[Tango Whisky]

In a spin, your left hand would be shifting the flaps to negative in order to help stop the spin, especially when you are close to the ground.
If the glider impacts the ground at a steep angle, the prop pylon will end up anywhere except its fully extended position.

[AS]

On Tuesday, October 19, 2021 at 4:09:46 AM UTC-4, Tango Whisky wrote:
> In a spin, your left hand would be shifting the flaps to negative in order to help stop the spin, especially when you are close to the ground.
> If the glider impacts the ground at a steep angle, the prop pylon will end up anywhere except its fully extended position. <

... and the front of the cockpit will be very much damaged yet the pictures in the report show the nose virtually intact. How is that angle in a flat spin compared to a 'normal' spin in an Arcus?

Uli
'AS'

[andy l]

Sorry to argue, but the majority of the pictures have most of the damage hidden underwater, with only the smashed nose cone obvious, and a hint of something on the right cockpit side. There are some with a relatively lower water level. Unfortunately none of the front cockpit is intact, and the rear is also noticeably damaged

[AS]

On Wednesday, October 20, 2021 at 5:59:44 AM UTC-4, andy l wrote:
> Sorry to argue, but the majority of the pictures have most of the damage hidden underwater, with only the smashed nose cone obvious, and a hint of something on the right cockpit side. There are some with a relatively lower water level. Unfortunately none of the front cockpit is intact, and the rear is also noticeably damaged

Andy - no argument here. You are right to point out that damage to the cockpit is visible. However, I have - unfortunately - seen a two-seater, which hit the ground under a steep angle and the front end was destroyed all the way to the wings with the very sad outcome for the two occupants.
Has technology advanced to the point that today's two-seat gliders have a crash/crush worthy cockpit structure akin to a F1 racecar? I doubt that. That's why I asked if someone knows how steep or shallow a flat-spin is in that glider, because I cannot believe that the damage was caused by an impact from a fully developed spin, where the nose is basically pointing straight down.

Uli
'AS'

[Tango Whisky]

It is pure speculation wether they have been in a fully developed spin during impact, or already been able to stop the rotation with not enough altitude to pull out.
In any case, there is no reason why an Arcus should enter a flat spin.

[Darren Braun]

Some good thoughts on this thread. But with a low altitude engine out, it's all about time... you have 1 minute or less to decide and execute and precisely fly the airplane. Anything that takes your attention away from flying the airplane will likely end it for you.
Darren "U2"

[2G]

On Friday, October 22, 2021 at 11:36:42 AM UTC-7, Darren Braun wrote:
> Some good thoughts on this thread. But with a low altitude engine out, it's all about time... you have 1 minute or less to decide and execute and precisely fly the airplane. Anything that takes your attention away from flying the airplane will likely end it for you.
> Darren "U2"

Yeah - it means you need to have your plan worked out in advance. A Navy pilot who ejected during a cold launch was asked when he decided to eject. His answer: I made the decision ten years ago.

Tom