Today's Message Index:
----------------------
1. 01:40 AM - =?ISO-8859-1?Q?Re=3A_Europa-List=3A_Woodcomp_Propellers? (Carl Pattinson)
2. 02:59 AM - Electric VP Prop Reliablity (Mark Burton)
3. 04:00 AM - Re: Woodcomp Propellers (stephan@scassel.se)
4. 04:49 AM - Re: Constant Speed Prop and failure modes. (nwcmc@tiscali.co.uk)
5. 06:05 AM - Re: Electric VP Prop Reliablity (Mark Burton)
6. 09:39 AM - Re: Constant Speed Props, etc. (ALAN YERLY)
7. 11:58 AM - Re: Constant Speed Props, etc. (Karl Heindl)
8. 02:07 PM - Re: Constant Speed Props, etc. (Paul McAllister)
9. 06:18 PM - Re: Constant Speed Props, etc. (Fred Klein)
10. 10:30 PM - Re: Constant Speed Props, etc. (ALAN YERLY)
11. 10:56 PM - Re: Constant Speed Props, etc. (ALAN YERLY)
Message 1
INDEX | Back to Main INDEX |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | =?ISO-8859-1?Q?Re=3A_Europa-List=3A_Woodcomp_Propellers? |
X-mailer: iAVMailScanner 1.5.6.4
My Woodcomp propeller (the one I need to modify) is William Mills old one
(it was not fitted to his aircraft at the time of his accident). It is about
three years old and was probably one of the first to be fitted in the UK.
For the avoidance of doubt these propellers are definitely fitted with an
end stop mechanism. If you look at the photo there is a machined groove to
the right of the bronze coloured cog. There is an M6 bolt through the front
of the hub which locates in the groove limiting the blade travel.
The problem is that this prop has the facility for reverse thrust so the end
stop is of no use if the motor takes the blade beyond fine pitch. Thats why
I need to get it modified. I assume that your propeller Jos will have been
the same.
To say that there is no mechanical stop is untrue. The majority of Woodcomp
propellers have a shorter groove which limits the travel between coarse and
fine (or fine and feathered if it is the feathering variety). Anyone with a
"normal" Woodcomp prop has nothing to worry about in this respect.
If a motor burns out you have to question whether it was protected properly
with the correct rating fuse. If the motor is subjected to extreme demands
it will draw more current and blow the fuse before the windings failed. Were
such a failure occurr with the normal mechanical stop arrangement the
propeller would still be in the normal range, continue to produce thrust and
the aircraft should be flyable.
Knowing what I know now I would still buy the Woodcomp propeller again but I
would not fit a propeller (of any make) that didnt have mechanical end
stops.
Variable pitch propellers carry additional risks (compared to fixed). So
does flying!!! All you can do is try and minimise them.
The moral is dont fly with a prop that can go into reverse - it isnt worth
the doubtful advantages.
Carl Pattinson
G-LABS
_______________________________________
No viruses found in this outgoing message
Scanned by iolo AntiVirus 1.5.6.4
http://www.iolo.com
Message 2
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Electric VP Prop Reliablity |
Folks,
What follows is a general comment and is not related to any specific failure of
an electric VP prop system.
Jos is right to question the quality of the electrics (motor/switches/diodes/wiring,
etc.) on the Woodcomp SR3000. However, in my opinion, the SR3000 is not
substantially different in quality compared to the other low-cost electric VP
props. In fact, I would rate another low-cost prop as having a far worse reliability
record than the SR3000 (motor burnouts, intermittent operation, etc.) I
also have experience of yet another manufacturer's products that have exhibited
electrical failures. So although Woodcomp could almost certainly do better,
they are not alone in this regard.
This potential for failure of the propeller system must be acknowledged by the
pilot and they should be mentally prepared for that eventuality. So, whatever
brand of VP prop you have (cheap or expensive), be prepared for it to stop functioning
at any time.
To reduce the chance of that happening, inspect the prop/hub/wiring regularly.
Ensure that the brushes are in good condition (slip rings clean) and that the
pitch change mechanism operates freely (but not with excessive backlash) throughout
the normal pitch range.
Most importantly, check that the range of pitch movement is such that the aircraft
can still fly with the pitch stuck at any position in that range.
With regard to hard pitch stops that come into effect if a switch fails, it would
be sensible to actually test that the fine pitch hard stop is in a position
that will help save your hide. I suggest that having determined the correct position
of the electrical switch, measure the static RPM with the pitch on the
limit and then (carefully) override the switch and move the pitch to the hard
limit (use a low voltage perhaps to move the pitch slowly to the stop?) You then
run the engine again and compare the static RPM with the static RPM you achieved
with the pitch on the electrical limit. You can decide on what is an acceptable
rise in RPM. Probably, not much given that the electrical limit was likely
to be set close to the finest position acceptable for safe operation.
Finally, make sure that the pilot (you) fully understands how the pitch is
controlled (controller modes, manual operation, etc.) and what the
appropriate controller settings are for the various flight scenarios.
As part of the pre-flight self-briefing before every flight, acknowledge the fact
that the pitch may freeze just as you acknowledge the fact that the donkey
may quit at any time.
Regards,
Mark
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=235337#235337
Message 3
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Woodcomp Propellers |
Hi
I have read the thread with great interest and I think I need to add some
facts. Some already stated by Jos and
Frans.
I have used WoodComp SR2000 for three years with 100% success so far. Also
vent to WoodComp
for a two days course in order to conduct service and get a better
understanding.
It was very interesting indeed.
The quality of the different propeller parts is very good. I was allowed
to put one SR2000 and one SR3000
together. Supervised of course :-)
Here goes my list of remarks
1.
WoodComp makes good propellers. Propellers installed on many
ultralights/experimentals with success
2.
SR2000 end stop is better then SR3000. More ruggedized. The micro switch
used on SR3000 is not the very best.
I was a bit surprised when I first saw them
3.
SR2000 has push-rods instead of gear in order to change pitch. That means
that the SR2000 can not move to superfine.
4.
When you throttle back in order to enter the landing pattern for example,
the RPM will drop as soon as the end stop has been reached as explained by
Jos
5.
Normally you do not throttle back as much as Jos did in cruise but that
was due the fact the controllers settings was wrong.
6.
The end-stop should not normally be reached turning from climb- to
cruise-regime as Frans explained
My conclusion:
End stop that works is mandatory. SR3000s micro switch is not the very best,
Jos reaction was human. He throttle back due the MAP reading.
Frans is correct the end stop was not the start of the event chain. The
incorrect setting seems to start the situation.
With a working end stop this sad accident would probably not happend
If the propeller goes wild or wrong setting: TURN OVER TO MANUAL. Use
manual now and then in order get used.
Drill this as much you simulate engine failure: Turn electric pump on
switch to reserve tank
One other thing worth mentioning here:
Set the HYSTERESIS regime to 100 (WoodComp recommendation)
That means that the regulator does not trigger the servo for minor changes
in prop-speed (rpm)
If the prop speed (rpm) drops let say 70 rpm, the servo will stay
passive. This saves the servo and the mechanics evidently
Best regards
Stephan Cassel
LN-STE Mono 140 hours
Message 4
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Constant Speed Prop and failure modes. |
It should also be remembered that a prop stuck in a coarse setting can
be an issue as well. To this end it is worth checking that the aircraft
can climb away safely from a go-around at short finals at low speed in
this condition.
I flew C-130s for 9 years and without doubt the propellers with their
control systems were studied more closely than any other technical
aspect of the aircraft. On this aircraft there are 6 different safety
features that are designed to limit the rpm of the engine. This was
particularly important for an engine/prop combination that was designed
to run at constant speed. On the RAF C-130s the engines produced about
5000shp each and the propeller angle could reach 55 degrees in the
cruise and keeping the rpm within the 98-102%rpm limit needed some high
quality engineering. The incident below whilst not relevant to the
Europa might make interesting reading.
An Orion aircraft (which uses the same engine/prop combination as the
C-130) had a very testing incident which makes one aware that, even
after many years of trouble free operation, it is possible to get into
a situation where a prop can bite. In this case the crew was flying in
a naval military exercise many miles offshore. This entailed a long
transit at high level, a significant amount of time of slow flight at
low level, followed by another high level transit back to their base.
The problem came when a fault in one of the propeller control systems
caused an outboard prop to pitch lock during the low level phase of the
flight. This is one of the safety features to prevent the prop going
too fine. However because of the power/altitude/speed combination the
prop was stuck in low pitch. This isnt normally a problem as the
engine speed can be contained by continuing to fly at a low TAS. It
still takes the total attention of one crew member using the throttle
to keep the rpm within limits. However in this case, to be able to
reach the nearest airfield, the aircraft needed to climb as it had
insufficient range at low altitude. The crew was faced with the choice
of a premeditated ditching or to intentionally increase the TAS by
climbing and accept the risk catastrophic failure as the prop was
forced into an overspeed situation. They decided to choose the latter.
The highest rpm that the safety features can normally cope with is
108%. As they climbed the prop rpm increased until finally the engine
and propeller broke away from their mountings. Afterwards this was
calculated to have happened at about 170%rpm. Fortunately the
engine/prop combination fell away without damaging the aircraft. The
crew managed to continue their flight to a safe landing.
When William Mills first flew into my strip with the first Woodcomp
prop with beta range capability I had a chat with him about the dangers
of props that can operate in the beta range. I thought it a risky
feature which was totally unnecessary on the Europa. As Jos found, even
in forward fine pitch the situation can very quickly become
uncontrollable should something go wrong.
I would suggest that owners of Europas with VP props may like to check
that the settings for the mechanical stops for both low and high pitch
on their propellers enable safe low speed flight.
Nigel Charles
Get up to 50% off Norton Security - http://www.tiscali.co.uk/securepc
_________________________________________________________
Message 5
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Electric VP Prop Reliablity |
In my previous message, I talked about checking that the fine pitch
hard stop was in a sensible position. I forgot to mention that if you want to do
that check, be very careful not to damage the switches in the hub because with
some hub designs (not all) if you overrun the limit switches, something will
break (most likely the switch). So, before you attempt such a test, look at
the switches and how they are activated and convince yourself that when the pitch
moves to the hard limit, nothing will be damaged.
You may feel that this test is not required as the manufacturer will have set the
hard stop to a suitable position. Personally, I no longer believe prop manufacturers
when they say they have set the limit switches to the correct position.
I am similarly sceptical about the position of hard limits.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=235350#235350
Message 6
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Constant Speed Props, etc. |
We haven't firmed that up yet Fred.
I believe the Sensenich blades are really designed for the new 432 and
much final testing needs to be done. Other blades are being tested
which appear to be retrofitable (is that a word?). Frankly I doubt
there will be a significant change over the WD blades, but that is what
testing is for. As you are aware, wider chord blades require a somewhat
larger base . I'll keep you guys posted on the testing as I get it as
we don't want to release a product until it is thoroughly tested or make
promises we can't keep.
As you well know I am not a politician.
Bud
Custom Flight Creations
www.customflightcreations.com<http://www.customflightcreations.com/>
----- Original Message -----
From: Fred Klein<mailto:fklein@orcasonline.com>
To: europa-list@matronics.com<mailto:europa-list@matronics.com>
Sent: Friday, March 20, 2009 1:56 AM
Subject: Re: Europa-List: Constant Speed Props, etc.
On Mar 19, 2009, at 9:11 PM, ALAN YERLY wrote:
Martin will be sending the new blades to me for test also. I will
run a test of the fixed warp drive, standard Airmaster AP332 with Warp
drive blades and the new Kiev blades.
Bud...Do you know whether or not the new blades are compatible w/ the
AP332 hub?
Fred
http://www.matronics.com/Navigator?Europa-List<http://www.matronics.com/N
avigator?Europa-List>
http://www.matronics.com/contribution<http://www.matronics.com/contributi
on>
Message 7
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Constant Speed Props, etc. |
What is a 432 ?
From: budyerly@msn.com
Subject: Re: Europa-List: Constant Speed Props=2C etc.
We haven't firmed that up yet Fred.
I believe the Sensenich blades are really designed for the new 432 and much
final testing needs to be done. Other blades are being tested which appea
r to be retrofitable (is that a word?). Frankly I doubt there will be a si
gnificant change over the WD blades=2C but that is what testing is for. As
you are aware=2C wider chord blades require a somewhat larger base . I'll
keep you guys posted on the testing as I get it as we don't want to releas
e a product until it is thoroughly tested or make promises we can't keep.
As you well know I am not a politician.
Bud
Custom Flight Creations
www.customflightcreations.com
----- Original Message -----
From: Fred Klein
Sent: Friday=2C March 20=2C 2009 1:56 AM
Subject: Re: Europa-List: Constant Speed Props=2C etc.
On Mar 19=2C 2009=2C at 9:11 PM=2C ALAN YERLY wrote:
Martin will be sending the new blades to me for test also. I will run a te
st of the fixed warp drive=2C standard Airmaster AP332 with Warp drive blad
es and the new Kiev blades.
Bud...Do you know whether or not the new blades are compatible w/ the AP332
hub?
Fred
href="http://www.matronics.com/Navigator?Europa-List">http://www.matronhr
ef="http://forums.matronics.com">http://forums.matronics.com
href="http://www.matronics.com/contribution">http://www.matronics.com/c
Message 8
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Constant Speed Props, etc. |
Hi Bud,
I am not an aerodynamicst, not even an amature one but I was wondering
why you didn't think the Kiev blades will be much of an improvement over
the Warp Drive blades. The reason I ask is that I do know that I get an
increase in TAS up to about 10,000' with my AP332 Warpdrive / 914T
combination, but after the speed doesnt increase much.
I hear from the Whirlwind folks that this is not the case for them, higher
faster.
Given that something isn't happening as expected I am concluding that there
is some design parameter(s) that are not appropriate for a an aircraft that
flies at Europa speeds / altitudes.
Any insight that you could share with me would be appreciated.
Thanks, Paul
On Fri, Mar 20, 2009 at 11:32 AM, ALAN YERLY <budyerly@msn.com> wrote:
> Frankly I doubt there will be a significant change over the WD blades,
> but that is what testing is for. As you are aware, wider chord
> blades require a somewhat larger base .
>
As you well know I am not a politician.
>
> Bud
>
>
Message 9
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Constant Speed Props, etc. |
On Mar 20, 2009, at 2:00 PM, Paul McAllister wrote:
> I am not an aerodynamicst, not even an amature one but I was
> wondering why you didn't think the Kiev blades will be much of an
> improvement over the Warp Drive blades.
Bud,
I too was surprised at your apparent skepticism as to whether those
Kiev blades may offer improvement over the current WD blades in the
Airmaster hub.
I had several long emails w/ Martin on the subject...perhaps 2 years
ago...and my recollection is that he was quite candid about the WD
blades being less than optimal given the flight envelope and length
limitations of the blades for the Europa. My understanding is that
the WD blade stock is much longer, and when cut down to length
required, they lose much of their twist...to such an extent I've read
that the inner portions of the blades create negative thrust under
certain conditions. I've speculated that the relative lack of twist
may be a factor in engine cooling...just speculation, I have, of
course, no direct experience.
Assuming that the "432" references a new hub, I hope it's available
with other than a Rotax flange.
Fred
Message 10
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Constant Speed Props, etc. |
Paul,
I am only a junior aerodynamicist. Propeller blade design is still a
zen art. Too many theta, beta sigma deltas to patiently wade through
and design a prop. The math is not beyond me, ( I have a computer
program for doing the gymnastics and iterations, (but my kid the aero
engineer has to get me in to it...go figure). I can say that most
designs take into account the assumptions of where the max efficiency of
their design will be optimized. When designing a prop blade, it is hard
to get a prop that does all things well. We buy a CS prop to accelerate
fast, give max climb and optimum efficiency at the exact torque/power
curve for the specified aircraft at a specified cruise speed and
altitude, but propeller blade designers don't know your plane, engine or
the altitudes you intend to use, so they assume for a specific engine
and speed/altitude, and don't tell anyone. For you Paul, the next two
paragraphs are a bit basic, but somebody less experienced may glean some
knowledge or correct me.
Example: For max static thrust and quick acceleration of say a float
plane/airboat, you design the prop so the entire prop blade is pulling
very close to the stall angle based on the rotational speed for takeoff
power/torque and forward speed. This gets the plane on the step quickly
and off the water. But, once you pass about 80 Kts the blade angle of
attack falls off due to forward speed, cowl stagnation point / flow
interruption and the reduction of power to max continuous for the climb.
To design a perfectly optimized fixed pitch propeller, the following is
optimized by trial and error: For takeoff, the blade bites as described
above. During the transition to climb, the tip unloads slightly and the
root takes up the difference. At cruise the tip unloads further leaving
the root to take up the slack. Balancing this twist means the propeller
designer and aircraft/power plant designer must cooperate to achieve
this goal. So the fixed pitch designer at WD makes his blade so that
there is extra pitch at the hub decreasing to the tip so as speed
increases the root pulls the load the tip can't, but only to a point.
Typically 7500-9500 feet and 120 Kts is about max you'll ever get unless
you've got a clean airplane like a Europa and you get 130 Kts...
Take the Airmaster with the Warp Drive (WD) blades. On a slow aircraft
like a Rans S-7 or a Kitfox. Let's say their optimum cruise will be 110
Kts at 7500 feet for that plane. A fixed 68 inch WD prop can be twisted
to give max static thrust, and high climb, but then the pitch is too low
for optimum cruise, and the plane only makes 105 Kts because the tip is
unloaded and prop efficiency drops. So we put the WD blades on a CS
prop hub. Now the static thrust and high climb are there but once at
cruise we adjust the pitch to coarse to allow the prop to bite more and
be at the optimum pitch for 110-115 Kts or a little higher.
Now let's go to our 914 and 15,000 foot cruise. The WD blade is a good
strong blade, but the assumed efficient cruise altitude of the blade may
not have been optimized for 15,000 feet and 175 KTAS pulled by an engine
making 70 HP and 70 ft lbs of torque at altitude. As altitude goes up,
we know the rules about how density affects the TAS. The blade (wing)
of the prop is now at a higher Reynolds number which results in a lower
lift curve slope. In the rarified air up there, the dynamic pressure is
less so less lift (or pull) is provided, and the velocity (True) is
higher, so the vector made by the rotational angle of the disk and the
Velocity vector forces the blade to a higher angle of attack to bite
(course prop pitch). The higher altitude decreases the thrust (or lift
of the blade) and you find yourself with the blade generating max lift,
and or in fact stalling at some point and not operating efficiently. I
believe it is a high probability the torque of the 914 engine is higher
than the prop requires for max efficiency at altitude. Hence the CS
mechanism adjusts the prop to a more coarse setting to absorb the torque
demanded by the throttle, but that puts the blade at an angle which
lowers the overall efficiency of the blade. Therefore you experience the
effect of no appreciable increase in speed the higher you go. The WD
blade is most probably being over driven by the 914 at altitude. I
presume you experimented with many manual pitch settings, manifold
pressures and RPM settings looking for max performance. I am well
behind you as my schedule does not allow a lot of time to climb to
altitude and test, but I am hoping for a break this spring. My gut
feeling will be that I will need to throttle back to gain efficiency and
be satisfied with 40 mpg instead of 30 and get to my destination a
little slower.
>From my Airplane Aerodynamics reference by Dommasch, Sherry and
Connolly, "Because of the factors discussed above, we find that the over
all shape of a propeller is determined by the maximum speed at which it
must operate efficiently. A low-speed planform should be slender with
well rounded tips, whereas a high speed planform should have a large
chord, with the maximum amount of blade area concentrated in the minimum
diameter. Because the major portion of the thrust is derived from the
outer portion of the blades, a high speed propeller is generally
characterized by paddle shaped tips that place the area where it can
best be utilized.
What's the fix? To translate the above academic explanation, the best
example is to look at WWII prop designs of the VDM propeller used on the
ME 109. Early versions had the thin profile blade we see on our WD
narrow chord blades. But as engine performance and the demand for
higher altitudes increased, the designers went to a wider prop of more
surface area to absorb the torque, and to create more thrust out of the
blade normally lost due to the effects of higher altitude. They were
limited by the diameter of the prop due to ground clearance, and
production forced them to stick to three blades so they fattened the
blades, increased the pitch of the root and went to war (see pictures of
the Ta 152 for an even higher altitude and speed prop). Takeoff
performance wasn't that much better because the larger blade area
demanded more torque/power than available and the pitch was reduced
lowering efficiency at takeoff, but mid altitude climb and acceleration,
as well as cruise was improved. By the way the VDM was a variable pitch
prop, with a visual indicator of prop pitch in the cockpit, not a
constant speed prop. Talk about pilot work load. In the US we did the
same for the P-47 by changing the Hamilton Standard prop from a thin
blade to a thicker blade as WD did and made the prop Constant Speed to
reduce pilot work load. God I love history...
Right now Airmaster is looking at a number of blades that fit our hub
and future hubs. Problem is, the blade designs are many, and twist
features are not that much different than the WD. My comment on the
Kiev blade is that it doesn't appear to have much more twist, but it
does seem to have more area. It is in use on lower altitude/low
performance ultralight and trike aircraft. It is light, but, is its
hollow design tough enough for the 914 at high Q, and for our Europa,
all the Kiev prop blades are longer (67") than we can normally use.
Sensenich (fixed) and Whirlwind (oil pump driven hydraulic) have wider
chord blades than the WD and may hold an advantage in some areas, but
give a thumping sound as the pressure wave hits the aircraft. Airmaster
does use their own Europa to test prop blade performance. In my
opinion, if some blade was significantly better for the three blade
AP332, it would be on there already. Since we have new meat in the
prop market, there are more choices in the blades, and the Rotax / WD is
very popular so the new blades favor that LSA speed/altitude market now
and use a similar hub attachment and blade design. I'm afraid there is
not a lot of call for high altitude low power high speed props like we
need for cruise at 15,000 feet. Also the market has to be satisfied,
many lower performance aircraft enjoy the Airmaster and aren't in need
of a major change, while other markets need a longer two blade prop for
static thrust. Wider blades restrict feathering or cowl clearance in
some aircraft. These are the things being evaluated at this time. It
takes time, money and testing.
Good Night,
Bud
----- Original Message -----
From: Paul McAllister<mailto:paul.the.aviator@gmail.com>
To: europa-list@matronics.com<mailto:europa-list@matronics.com>
Sent: Friday, March 20, 2009 5:00 PM
Subject: Re: Europa-List: Constant Speed Props, etc.
Hi Bud,
I am not an aerodynamicst, not even an amature one but I was wondering
why you didn't think the Kiev blades will be much of an improvement
over the Warp Drive blades. The reason I ask is that I do know that I
get an increase in TAS up to about 10,000' with my AP332 Warpdrive /
914T combination, but after the speed doesnt increase much.
I hear from the Whirlwind folks that this is not the case for them,
higher = faster.
Given that something isn't happening as expected I am concluding that
there is some design parameter(s) that are not appropriate for a an
aircraft that flies at Europa speeds / altitudes.
Any insight that you could share with me would be appreciated.
Thanks, Paul
On Fri, Mar 20, 2009 at 11:32 AM, ALAN YERLY
<budyerly@msn.com<mailto:budyerly@msn.com>> wrote:
Frankly I doubt there will be a significant change over the WD
blades, but that is what testing is for. As you are aware, wider chord
blades require a somewhat larger base .
As you well know I am not a politician.
Bud
http://www.matronics.com/Navigator?Europa-List<http://www.matronics.com/N
avigator?Europa-List>
http://www.matronics.com/contribution<http://www.matronics.com/contributi
on>
Message 11
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Constant Speed Props, etc. |
Fred,
See my other post to Paul.
I agree about the Warp Drive Blades. Even in the longer blade lengths
it is not the best blade for altitude. I find them very good in the
7500 to 9500 foot range for our aircraft using 100 Hp engines. It is
not a perfect world. The Kiev blades appear too long also. Ergo, my
fear is the blade will be less efficient when trimmed for our plane
unless those pesky Russians remake the blades for us as you normally
can't whack a hollow blade prop to length.
Maybe VDM will make a smaller version of the Me109 blade for our use.
Anybody know them?
I never thought of myself as skeptical, just cautiously
optimistic...(Sarcastic humor through years of training though.) Bottom
line testing will tell. I'm excited about the near future, but patient.
Bud
----- Original Message -----
From: Fred Klein<mailto:fklein@orcasonline.com>
To: europa-list@matronics.com<mailto:europa-list@matronics.com>
Sent: Friday, March 20, 2009 9:12 PM
Subject: Re: Europa-List: Constant Speed Props, etc.
<fklein@orcasonline.com<mailto:fklein@orcasonline.com>>
On Mar 20, 2009, at 2:00 PM, Paul McAllister wrote:
> I am not an aerodynamicst, not even an amature one but I was
> wondering why you didn't think the Kiev blades will be much of an
> improvement over the Warp Drive blades.
Bud,
I too was surprised at your apparent skepticism as to whether those
Kiev blades may offer improvement over the current WD blades in the
Airmaster hub.
I had several long emails w/ Martin on the subject...perhaps 2 years
ago...and my recollection is that he was quite candid about the WD
blades being less than optimal given the flight envelope and length
limitations of the blades for the Europa. My understanding is that
the WD blade stock is much longer, and when cut down to length
required, they lose much of their twist...to such an extent I've read
that the inner portions of the blades create negative thrust under
certain conditions. I've speculated that the relative lack of twist
may be a factor in engine cooling...just speculation, I have, of
course, no direct experience.
Assuming that the "432" references a new hub, I hope it's available
with other than a Rotax flange.
Fred
http://www.matronics.com/Navigator?Europa-List<http://www.matronics.com/N
avigator?Europa-List>
http://www.matronics.com/contribution<http://www.matronics.com/contributi
on>
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|