<<flap fiddling to get the stall below 45 KTS>>
Has anyone tried that? What, for example, does 30 degrees or 35 degrees
of flap confer in terms of any stall speed reduction? (Non-monowheel a/c
only)
Duncan Mcf.
----- Original Message -----
From: Robert Borger
To: europa-list@matronics.com
Sent: Wednesday, July 21, 2010 2:18 AM
Subject: Re: Europa-List: ELSA max speed solution.
Bud,
If you can get the stall speed down to the required 45 KTS, there is
another solution to the max speed issue. You can "derate" the engine.
State in your operating limitations that you are limited to 5800 RPM
(or whatever max RPM is for the 912 or 912S) to, say, 5 or 10 minutes
for takeoff and climb. After that, the operator is limited to a max of
5500 RPM or whatever is necessary to hold the speed down to 120 KTS max.
This provides full power for takeoff and initial climb and provides
your 120 KT cruise at 3 GPH. No need to resort to adding extra special
drag to mess up the Europa's wonderful efficiency.
So you build a tri-gear (or conventional gear) with Rotax 912 or 912S
and a Warp Drive ground adjustable prop. Build it as light as possible
for best useful load. License it for 1320 lbs max gross. Use your VGs
and flap fiddling to get the stall below 45 KTS and derate the engine
for whatever power provides you with 120 KT cruise.
Just like that you have an Amateur Built Experimental that meets LSA
requirements.
Just my two bits. Fire away!
Check six,
Bob Borger
Europa Kit #A221 N914XL, XS Mono, Intercooled 914, Airmaster C/S
http://www.europaowners.org/forums/gallery2.php?g2_itemId=60232
http://www.biplaneforumgallery.com/index.php?cat=10046
Europa Flying!
3705 Lynchburg Dr.
Corinth, TX 76208
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On Jul 20, 2010, at 12:49, Bud Yerly wrote:
To all.
N12AY is a Classic Trigear placarded GW 1320, has completed most of
it's test flights. After 4 months of testing, I will have a complete
write up soon. Note, if your Europa has been registered above 1320 lbs,
it does not qualify for an E- LSA ever. For those of you who have 1300
lb registrations on your flying Europa Classic, convert it to a fixed
trigear if needed, add a fixed pitch prop, and if you started with a
reasonable empty weight, add some vortex generators and do some tweaking
and it will allow the plane to meet the criteria of 45 Kt stall, and 120
Kts at max continuous power. (Dirty up your wheel pants to keep the
speed down if necessary). The XS wing is nearly 50 lbs heavier,
slightly larger, and should also be able to meet the stall speed.
Problem is the empty weight is a bit high on the XS unless you are a
weight zealot. If you are a weight zealot, the XS should be eligible
provided you have not already registered it's gross weight as over 1320.
Darn those rules.
By adding vortex generators (and I prefer adjusting the flap rig
slightly down), the aircraft at 1320 lbs stalls at 45 Kts. The handling
of the plane with the VGs is superb at low speed. 18 degrees deck
angle, flaps up at 50 Kts indicated (Actual corrected speed is 47Kts.)
Burble starts at 50, the nose starts wandering about 47, the heavy
buffet begins at 45, break shortly afterwards. VGs run from the tip to
24 inches short of the wing root, and 7% chord seems to work well. Max
continuous power setting speed runs with my old 914 power, wing speed
kit and wheel pants only drops my top end 2-3 knots, as the Warp Drive
prop is set at 29.5 degrees for 5200 static on full 38 inches power on
the ground runs. You can imagine the rpm really drops when pulling it
out of turbo. A 912 with 2.2 gearbox or 912S should be perfect for the
LSA.
The XS style pitot static is a problem, and I had to install cockpit
static to get accurate readings. I've spent a lot of time flying speed
runs, experimenting with pitot tubes etc., trying to calibrate my speed
indications at these low speeds. The XS pitot is quite good down to
about 65 Kts indicated (indicating 3 knots high) and is dead on above 80
(I am using a Winter A/S indicator and a Blue Mountain for indications).
Speed runs are done with GPS and timed runs.
I am now tweaking the flaps a tiny bit as it makes 45 knots quite
controllable. Actually with a little tweak of the trailing edge, the
plane would only need flaps for drag.
More to follow. Weather and workload are slowing me down.
Bud Yerly
Custom Flight Creations
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