Today's Message Index:
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1. 09:51 AM - Re: Allegro 2000 CG (aerosiam)
2. 10:07 AM - Vortex generators tested on Allegro (aerosiam)
3. 11:01 AM - Re: Stall Warning System (aerosiam)
4. 11:31 AM - Re: Rotax 912ULS overheating issues (aerosiam)
Message 1
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Subject: | Re: Allegro 2000 CG |
Attached is Thom Riddles weight and balance excel
My 2005 Allegro 100hp came with the CG just slightly forward of the forward limit
so I fitted a 2.2lb weight in the tail. As you can see from the excel, 2 pilots
full fuel and baggage gives 29%
Forward limit is an 85lb pilot. Even putting 44lb baggage in the equation (max
22lb), it gets nowhere near the rear CG limit. Empty is 10 inches, 1 inch forward
of the forward limit
Regards
Paul
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=184886#184886
Attachments:
http://forums.matronics.com//files/wandb_tail_weight_490.xls
Message 2
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Subject: | Vortex generators tested on Allegro |
VORTEX GENERATORS
Please open Word attachment. The speed data has not come out correctly on this
post. (The flap settings have appeared as a phone number!)Pictures of VGs fitted
to Allegro in another post.
Allegro 2000 first test flight with Stolspeed VGs.
3 flights, total time about 2.5 hrs flown with instructor Michael Peare
Density alt 2,600'
CG close to forward limit
Weight 490 KG
Pictures and info for VGs at www.stolspeed.com
Test 1 - VGs half span
Test 2 - VGs full span
Test 3 VGs full span but leave gap of 80cms (30in) at wing root
POWER OFF POWER ON 3000 RPM
Flap setting 0 15 48 0 15 48
NO VG 45 40 36 44 38 35
HALF SPAN VG 43 36 36 43 37 34
FULL SPAN VG 41 36 34 38 36 34
Stall sp reduced 4 4 2 6 2 1
Airspeeds in knots Dynon and ASI both calibrated
No VGs
Aircraft breaks and drops right wing. Significant wing drop with power on.
Little buffet just before stall. Ailerons have adverse yaw close to stall. Needs
some rudder to correct wing drop.
Ailerons a little heavy.
Test 1 - VGs half span and VGs on vertical stabiliser
Ailerons lighter, more effective.
A lot of buffet warning
Power off - no break, no wing drop. Stick full back, aircraft nose high and buffets
Power on - mild wing drop, quick recovery.
Can be rolled 30 left 30 right a few knots below stall. Stable.
Ailerons can be used to roll level after stall.
Can fly 40 degree banked turn few knots below stall. Aircraft buffets and purpoises
but does not break.
Small reduction stall speed except power off reduced 4 kts @ half flap
Test 2 - VGs full span
Ailerons same as test 1.
Reduced buffet
Power off - mild wing drop, quick recovery. At zero flap, no break, descends 500'/min
Power on - break and mild wing drop, quick recovery
Significant reduction in clean stall speed, power on/off.
Aircraft can be trimmed to fly at 38 knots full flap with very high nose angle.
Stable.
Test 3 - removed VGs at the wing root (approx span of the elevator) to try to get
the strong buffet in test 1 with half span VGs. Made no difference.
Notes.
Factory stall warning gave good warning under all tests. For example power off,
full flap the stall warn sounds @ 42, buffet @ 37 and stall 34
Right wing drop even from left turn with left rudder 34 kts 3,800 RPM
Increasing RPM to 4,000 full flap, stall speed same, 34 kts, wing drop not significantly
worse with more power (very different to standard config with no VGs)
Stall speeds in POH say 43 - 39 - 35 kts
Conclusion
The VGs on the tail did not seem to give a noticeable difference in handling.
Results broadly similar to many aircraft i.e. large difference in clean stall speed,
less so in approach configuration.
Half VGs gave the best handling but a small reduction in stall
Full VGs gave good reduction of stall speed but less buffet and more wing drop
than half span
The Allegro has powerful 48 degree flaps. The inboard span stalls long before the
outboard and the VGs cannot help much.
Big difference in aileron response. Much nicer to fly. Although Allegro has 11m
wingspan, it feels light in roll.
Surprisingly, removing the VGs close to the wing root did not bring back the buffet
that was present with half span VGs
These VGs were a simple and inexpensive way to improve safety and handling
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=184892#184892
Attachments:
http://forums.matronics.com//files/vg_allegro_report_vgs_351.doc
Message 3
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Subject: | Re: Stall Warning System |
Hugh
My LED was red-green. It stopped working within a few hours. The red would come
on with start up then change to green at take off speed. Red indicated a stall.
I think I sent you some photos a while back when I had my panel out. I can look
for them again.
The system is a little quirky and sometimes sounds on the ground when taxying in
a cross wind but it works well in the air and gives about 5 to 7 kts warning
before the break.
Regards
Paul
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=184901#184901
Message 4
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Subject: | Re: Rotax 912ULS overheating issues |
We fly an Allegro 2000 100hp in Thailand with temperatures around 28 to 35 degrees
(82 to 96F). It would overheat within 10 mins of startup at 2200 rpm and needed
very gentle climbouts.
We fitted EvansCool and opened a circular hole in the lower cowling and enlarged
the oil cooler opening about 3 times. (See picture)
The oil runs too cool now and once a day we have to get the oil temperature over
100C (250F) - Rotax say this must be done to avoid condensation problems in
the oil system.
The additional oil cooling and reduction in cyl head temp with the extra airflow
is now acceptable and it never goes over 130C. (Max 150C) We checked the senders
in boiling water - they were underreading on the guage by about 10F.
The best solution is probably to fit the Rotax cooling baffle. I have a friend
with an 80hp who has it fitted and the opening is only about 1.5 in diameter but
it never overheats. The problem is that the baffle is very expensive.
Regards
Paul
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=184906#184906
Attachments:
http://forums.matronics.com//files/img_0646_151.jpg
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