Stemme S12 in Michigan this Saturday, May 20th (KOZW) @ 4 pm

Arcus overheating: I understand that one cannot run at full power for more than a few minutes with the ArcusM (or 32?). Sorry if I'm mistaken. Please explain further if I am. I also understood ArcusM's were impractical to cruise long distances under power (again, please correct me if I am mistaken). Also, IMO, the motor operation systems (despite improvements) are still slightly "finicky" (my experience)." As I understand it, the ArcusM and others like it are designed for self launch over an airfield and immediate soaring, not cross country cruising under power. In contrast, the Stemme can cruise easily at 140 knots for almost 1000 miles. One thing I love about the Stemme is that if the good weather is 50 or even 100 miles away, one can fly there under power in minutes. So, cross country cruising practicality (overheating, speed, efficiency, lack of ground handing at far off destination vs the Stemme which can easily taxi and tie out, etc.) is what I'm getting at regarding over-heating. If ArcusM owners are doing this kind of power flying, and over-heating is no concern, I had no idea.

Stemme S12 impressions: The Stemme was unbelievably practical in terms of rigging and hangaring and taxiing (vs ground handling and towing out to runway) and of course general self launch flying charateristics. But the gleaming advantage I see is he Stemme's especially quick, easy and reliable engine start and general operation when soaring and needing the motor to start NOW. After flying in the Stemme yesterday I realized almost immediately that there is simply no comparison in these areas to any other glider with the exception of FES. I flew for an hour into 25 mph headwinds, got low (1200 ft) and within 3 seconds of saying "ok, that's enough" the engine was running and the throttle was being advanced. The only downside I can see is that landouts in fields are not a good option (flipping over forward in soft ground is a risk) and once in said field getting out would be a major undertaking. That and of course the fairly significant price tag. But overall as a self launching motorgliders this thing is incredible.

Again, it is an interesting decision. I also wish to fly at an airport where the Arcus or 32 would be very impractical (likely impossible). I would need to integrate with moderate regional airport power traffic and there is no grass parallel for glider operations.

All I can say is that the world would be a better place with many more Stemme's (or ArcusMs or 32s) available for Cross Country training. 20 minutes from arriving at the airport and taking the keys out of the cars ignition, the Stemme can be at altitude and soaring cross country. That is a unique and almost magical capability.

On Tuesday, May 23, 2017 at 11:31:44 AM UTC-4, Sean Fidler wrote:
Arcus overheating: I understand that one cannot run at full power
for more than a few minutes with the ArcusM (or 32?).
Sorry if I'm mistaken.

You are mistaken; ArcusM (unlike 32) has no time-limit on max power.
Max RPM is limited to 5 minutes 6600-6700, but max power is 6600 anyway.
Range in the manual (with 3 tanks) is listed as 135nm.

As I understand it, the ArcusM and others like it are designed for
self launch over an airfield and immediate soaring, not cross
country cruising under power.

Yup. Absolutely not optimized for XC cruise under power.

The only downside I can see is that landouts in fields are not a good option
(flipping over forward in soft ground is a risk) and once in said field
getting out would be a major undertaking.

And field landings are prohibited in the manual IIRC.
So Stemme owners I know must be much more conservative about getting low.
As in any motorglider, landing is plan A. Plan B is when the motor starts.

I also wish to fly at an airport where the Arcus or 32 would be very
impractical (likely impossible). I would need to integrate with moderate
regional airport power traffic and there is no grass parallel for
glider operations.

I fly my ArcusM at a regional airport with plenty of power traffic.
No problem to assemble solo in the AM and taxi (to and from runway).
You've seen me taxi to runway and back to your hangar at your home field.
Its a different machine than Stemme, but perhaps not as limited as you imagine...

Maybe I'll get the boys to bring the Ionia Arcus over to the Howell airport and see how it taxis. No question that the ArcusM is a phenomenal sailplane.

Thanks Dave.

On Tuesday, May 23, 2017 at 1:26:01 PM UTC-4, Sean Fidler wrote:
Maybe I'll get the boys to bring the Ionia Arcus over to the Howell airport and see how it taxis. No question that the ArcusM is a phenomenal sailplane.

Thanks Dave.

The only issue for these big birds is availability of wide taxiways. I am lucky that from the hangar to a runway I have probably 150-200 feet wide path. I have a wing tip wheel so all of my wing needs to be on the taxi way. Some airports don't have taxiways wide enough for a 21 m ship like mine. So there is always a reason to put on the 18 m tips. Arcus has a wing wheel a few feet inboard from the wing tip and that will probably solve the narrow taxiway problem. The wankel will also easily cruise to a destination at low power settings with no heating up issues at all. You don't need full power for cruise. You would exceed speed limit for the airframe if you tried to maintain a level flight with full power.

On Tuesday, May 23, 2017 at 12:26:01 PM UTC-5, Sean Fidler wrote:
Maybe I'll get the boys to bring the Ionia Arcus over to the Howell airport and see how it taxis. No question that the ArcusM is a phenomenal sailplane.

Thanks Dave.

All the older Stemmes' are above gross weight with 2 normal people and a little gas on board. When I pointed that out to a Stemme rep at Oshkosh some time ago, he quickly tried to change the subject. The latest model has a MTOW of 900 kg but they don't list an empty weight anywhere. Legally most Stemmes can't be flown dual but they obviously don't fall apart if you do. I was not as impressed with the glider as Sean when taking a flight with Glider Bob years ago.
Herb

It's definitely big 25 meter glider (by far the largest I have ever flown) but it was still very fun to thermal soar. I guess it's more balanced that the S10, but not sure what that means exactly (hands off in bank). I have no real S10 experience with which to compare.

Also the prop assembly needs refurbishing every 200 hours at some not insignificant expense.

Updated Pics: https://www.icloud.com/sharedalbum/#B0tGDZLe8GvCM0b

On Tuesday, May 23, 2017 at 5:11:11 PM UTC-4, Andrzej Kobus wrote:
On Tuesday, May 23, 2017 at 1:26:01 PM UTC-4, Sean Fidler wrote:
Maybe I'll get the boys to bring the Ionia Arcus over to the Howell airport and see how it taxis. No question that the ArcusM is a phenomenal sailplane.

Thanks Dave.

The only issue for these big birds is availability of wide taxiways.
I am lucky that from the hangar to a runway I have probably 150-200 feet
wide path. I have a wing tip wheel so all of my wing needs to be on the
taxi way. Some airports don't have taxiways wide enough for a 21 m
ship like mine. So there is always a reason to put on the 18 m tips.
Arcus has a wing wheel a few feet inboard from the wing tip and that
will probably solve the narrow taxiway problem. The wankel will also
easily cruise to a destination at low power settings with no heating
up issues at all. You don't need full power for cruise. You would
exceed speed limit for the airframe if you tried to maintain a
level flight with full power.

All true. Antares at 20m gives me less than 1" extra space to edge of
taxiway (standard USA size) so requires some care, but tailwheel-in-rudder
and heavy tail weight gives precise steering so this is doable.
Arcus with inboard wing-wheel or Antares at 18m make this less critical.

Stemme has a different issue: it can get "rocking" (in roll) and hit a tip.
I know this has happened more than once (on grass fields) - damage results.

Always trade-offs!

See ya, Dave

I thought I read where the S-12 wheelbase was wider than the S-10, so the rockinrollin might be less of an issue.

On Tuesday, May 23, 2017 at 8:18:42 PM UTC-4, Duster wrote:
I thought I read where the S-12 wheelbase was wider than the S-10,
so the rockinrollin might be less of an issue.

I don't know, but also span is bigger....

With its dual main wheels, the Stemme can taxi on a very narrow taxiway
since the wings are always level. In crowded areas, however, the wing
span can be a problem. That can be solved by having the wings folded in
congested areas.

On 5/23/2017 3:11 PM, Andrzej Kobus wrote:
On Tuesday, May 23, 2017 at 1:26:01 PM UTC-4, Sean Fidler wrote:
Maybe I'll get the boys to bring the Ionia Arcus over to the Howell airport and see how it taxis. No question that the ArcusM is a phenomenal sailplane.

Thanks Dave.
The only issue for these big birds is availability of wide taxiways. I am lucky that from the hangar to a runway I have probably 150-200 feet wide path. I have a wing tip wheel so all of my wing needs to be on the taxi way. Some airports don't have taxiways wide enough for a 21 m ship like mine. So there is always a reason to put on the 18 m tips. Arcus has a wing wheel a few feet inboard from the wing tip and that will probably solve the narrow taxiway problem. The wankel will also easily cruise to a destination at low power settings with no heating up issues at all. You don't need full power for cruise. You would exceed speed limit for the airframe if you tried to maintain a level flight with full power.

--
Dan, 5J