Today's Message Index:
----------------------
1. 06:26 AM - Re: Allegro Cruise Speeds (Thom Riddle)
2. 10:26 AM - amphibious floats (Airgriff2@aol.com)
3. 10:27 AM - Structural Area Abrasion ALERT (Thom Riddle)
4. 12:36 PM - Re: Website information (Airgriff2@aol.com)
5. 08:12 PM - Re: Website information (Paul@AeroSiam)
6. 08:35 PM - Re: Allegro Cruise Speeds (Aero Siam)
Message 1
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| Subject: | Re: Allegro Cruise Speeds |
Paul,
Based on what I've been told by a guy I know flying a Kolb Mark III
experimental the 912S is not as fuel efficient at the 912. He flew his
Mark III for a few years with the 912, putting over 1800 hours on it,
then installed a 912S and has been flying that for a little over 2000
hours. If anyone should know it is him. He flies that airplane all
across the USA and Canada, include three trips to Alaska north of the
arctic circle. He was happy with the 912 in every way except he needed
more power to fly over the Rocky Mountains which he does regularly,
even though he lives in Alabama, over 1,000 miles east of the Rockies.
With all his cross country flying he says that in his normal cruise
configuration he got 4 gph with the 912 and 5 gph with the 912S with
only about 5 mph difference in cruise speed. Of course this is with a
slower airplane so the speed difference is less than in the Allegro.
I know that the 912 burns 4.0 gph at 75% power (max cruise HP). Based
on this fact, I calculate the following:
75% x 79 hp = 59.25 hp at cruise
4.0 gph x 6 lb. per gal = 24.0 lb. per hr.
24.0 lb. per hr / 59.25 hp = .405 lb. per HP per hour at 75% cruise
power
Assuming the Kolb pilot is flying the 912S at 75% cruise (max cruise
HP), the following similar calculations yield:
75% x 95 hp = 71.25 hp at cruise
5.0 gph x 6 lb. per gal = 30.0 lb. per hr.
30.0 lb. per hr / 71.25 hp = .421 lb. per HP per hour at 75% cruise
power
The lb. per hour per HP figures are used to compare efficiencies at
specific power settings. Within normal cruise power ranges, say 60% to
80% or so, these numbers should hold close to constant. Typically for
aircraft engines, at higher or lower power settings the efficiencies
are not quite as good.
That said, I would feel comfortable with the following numbers for the
912S:
Power Fuel Consumption (US gph)
60% 4.0 gph
65% 4.3
70% 4.7
75% 5.0
80% 5.3
Outside this range the fuel burn will probably be greater(per HP) than
this but I don't know by how much. You may be able to make educated
guesses by comparing real world fuel burn rates with what is in the
Rotax manuals. BTW, the fuel burn numbers in the Rotax manuals are
notoriously conservative, especially for the 2-stroke engines, so I
would not use them.... too pessimistic.
Worth noting is the fact that the lower compression 912 requires only
87 Octane fuel vs. the higher compression 912S which requires 91 Octane
fuel. I burn 87 Octane auto fuel in both my 912 engines and they are
quite happy with that fuel. Some people run higher octane than is
required but it is a waste of money.
Thom
Message 2
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| Subject: | amphibious floats |
"Good morning ", Amphibious floats for the Allegro are coming to the USA.
In about 8 weeks, the factory people will be training dealers here in the
states to fly and aquaint themselves with this new option which will be availiable.
We will be attending this forum. For further information:
contact
www.landlsportaviation.com
fly safe
Bob Griffin
Message 3
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| Subject: | Structural Area Abrasion ALERT |
Allegro Flyers:
Structural Area Abrasion ALERT
While at the hangar yesterday showing the Allegro to someone, he looked
under the Right SIde seat and noticed that the re-enforced area of the
fuselage bottom (seen inside) where the main gear leg attaches, there
was evidence of serious abrasion and gradual deterioration of this very
important area. Upon investigation, I determined it was caused by a
rivet used to fasten the seat support webbing to the fiberglass seat
shell. The rivet protruded enough to hit the front edge of the gear
re-enforcement area the way I had the seat adjusted. I am relatively
short in leg but long in torso so I had the seat back dropped down far
enough and the seat mover forward enough for this to occur. I didn't
have my camera with me so I did not get a picture of this. HOWEVER, I
borrowed a picture from Aero-Siam's website that showed just the area
the problem occurred. I've marked up a copy of Paul's picture and
attached it here.
Note that this could occur on either seat at either rivet location and
either in the front or back part of the gear leg attachment
re-enforcement location.
I am copying this to the factory and all know dealers. I am raising my
seat backs so this does not reoccur or get worse and will be patching
this abraded area as soon as I can. I hope the factory can develop and
recommend a solution to this.
Message 4
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| Subject: | Re: Website information |
Hi Paul, I checked your web site and was very impressed. It was Great! Good
luck with your new dealership.
Fly Safe
Bob Griffin
Message 5
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| From: | "Paul@AeroSiam" <Paul@aero-siam.com> |
| Subject: | Re: Website information |
Hi Bob
Thanks for the feedback on the website.
Hopefully the Allegro list will grow quickly and we can help eachother out. Thom
has a lot of useful info.
Paul
----- Original Message -----
From: Airgriff2@aol.com
To: allegro-list@matronics.com
Sent: Sunday, February 05, 2006 3:35 AM
Subject: Re: Allegro-List: Website information
Hi Paul, I checked your web site and was very impressed. It was Great! Good luck
with your new dealership.
Fly Safe
Bob Griffin
Message 6
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| Subject: | Re: Allegro Cruise Speeds |
--> Allegro-List message posted by: "Aero Siam" <paul@aero-siam.com>
Thom
Thanks again for your detailed info about fuel consumption and the experiences
of your friend with the Kolb. I am still working on an update to the website.
A couple more points - how is 75% power defined? I have seen it quoted by people
at anywhere between 4800 and 5400 RPM. If 75% power equates to about 71hp for
the 912S then looking at Rotax's website, 71hp hits the line at about 4200 RPM
which seems way low. What's the solution?
Pitching the prop. Does anyone have any info about the performance differences
with the Woodcomp prop set fine and coarse. It would be interesting to do an article
sometime for both engines showing the performance range at both ends of
the scale.
Paul
Aero Siam
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=10125#10125
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