Today's Message Index:
----------------------
1. 05:50 AM - Ews Bull air races (charles heathco)
2. 06:06 AM - Re: Ews Bull air races (luckymacy@comcast.net (lucky))
3. 06:10 AM - CG issues, was Battery on 200 HP Tubro 7A (Glen Matejcek)
4. 07:01 AM - Re: CG issues, was Battery on 200 HP Tubro 7A (Ken Simmons)
5. 07:06 AM - Kens report on exceeding VNE at Alt. (charles heathco)
6. 07:08 AM - Re: CG issues, was Battery on 200 HP Tubro 7A (Kevin Horton)
7. 07:33 AM - Re: Kens report on exceeding VNE at Alt. (Dan Beadle)
8. 07:51 AM - Greetings (charles heathco)
9. 08:23 AM - Re: Battery on 200 HP Tubro 7A (Jeff Dowling)
10. 08:29 AM - Re: Kens report on exceeding VNE at Alt. (Ron Lee)
11. 09:13 AM - Re: CG issues, was Battery on 200 HP Tubro 7A (Mickey Coggins)
12. 09:20 AM - Re: Battery on 200 HP Tubro 7A ()
13. 10:03 AM - Re: Kens report on exceeding VNE at Alt. (Kevin Horton)
14. 10:19 AM - Vortex Generators: one RV4 experience and cruise penalty discussion (Mark Todd)
15. 10:34 AM - Re: Kens report on exceeding VNE at Alt. (Rob Prior (rv7))
16. 11:36 AM - Re: Kens report on exceeding VNE at Alt. (LessDragProd@aol.com)
17. 11:51 AM - Dynafocal motor mounts (Vincent Osburn)
18. 12:28 PM - Market value of our RVs (was battery location for 200 HP turbo 7A (Stephen J. Soule)
19. 12:29 PM - Market value of our RVs (was battery location for 200 HP turbo 7A (Stephen J. Soule)
20. 01:25 PM - Re: Dynafocal motor mounts (Dick DeCramer)
21. 01:37 PM - Re: Kens report on exceeding VNE at Alt. (Dan Beadle)
22. 01:50 PM - Fittings and sealants (Bob Collins)
23. 02:55 PM - Re: Market value of our RVs (was battery location for 200 HP turbo 7A) (LarryRobertHelming)
24. 02:55 PM - Re: Kens report on exceeding VNE at Alt. (Alex Peterson)
25. 03:12 PM - Re: Fittings and sealants (linn walters)
26. 03:59 PM - Re: Kens report on exceeding VNE at Alt. (Ron Lee)
27. 04:11 PM - Re: Kens report on exceeding VNE at Alt. (rv6n6r@comcast.net)
28. 04:32 PM - Re: Kens report on exceeding VNE at Alt. (Olen Goodwin)
29. 05:06 PM - Time in the tanks, was Kens report on exceeding VNE at Alt. (Michael McGee)
30. 05:38 PM - Re: Kens report on exceeding VNE at Alt. (sportav8r@aol.com)
31. 05:40 PM - Re: Kens report on exceeding VNE at Alt. (Dan Beadle)
32. 06:05 PM - Re: Kens report on exceeding VNE at Alt. (Gordon or Marge Comfort)
33. 06:20 PM - Re: Fittings and sealants (LARRY ADAMSON)
34. 07:53 PM - Re: Time in the tanks (Ed Holyoke)
Message 1
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| Subject: | Ews Bull air races |
--> RV-List message posted by: "charles heathco" <cheathco@junct.com>
Hiya m, wanted to put this out for all who may not know about it, NBC is airing
the races at 2pm Central, today, Sat. Charlie heathco Do not archive
Message 2
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| Subject: | Re: Ews Bull air races |
--> RV-List message posted by: luckymacy@comcast.net (lucky)
Thanks for the info. TV guide's show description doesn't sound like today's show
is dedicated to just the air race so don't get your hopes up too high. Hope
I'm wrong.
lucky
-------------- Original message --------------
From: "charles heathco" <cheathco@junct.com>
> --> RV-List message posted by: "charles heathco"
>
> Hiya m, wanted to put this out for all who may not know about it, NBC is airing
> the races at 2pm Central, today, Sat. Charlie heathco Do not archive
>
>
>
>
>
>
Thanks for the info. TV guide's show description doesn't sound like today's show
is dedicated to just the air race so don't get your hopes up too high. Hope
I'm wrong.
lucky
-------------- Original message --------------
From: "charles heathco" cheathco@junct.com
-- RV-List message posted by: "charles heathco" <CHEATHCO@JUNCT.COM>
Hiya m, wanted to put this out for all who may not know about it, NBC is airing
the races at 2pm Central, today, Sat. Charlie heathco Do not archive
_- - List Contribution Web Site -
Message 3
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| Subject: | CG issues, was Battery on 200 HP Tubro 7A |
--> RV-List message posted by: "Glen Matejcek" <aerobubba@earthlink.net>
>Be careful that you consider the polar moment of inertia problem as well.
>Think dumbbells vs bowling balls. Both have the cg in the center, but boy
oh
>
>boy are the spin characteristics different.
Excellent reminder, Gary! Along those lines, does anybody know whatever
became of the fellows that used a 4" or so dia tube through the outboard
LE lightening holes as aux fuel tanks? They were at OSH a couple years
ago, trying to sell their idea. At the time they hadn't done any spin
testing, and didn't seem to have considered roll coupling or the effects of
maneuvering on the location of the fuel within the tanks...
Glen Matejcek
aerobubba@earthlink.net
Message 4
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| Subject: | Re: CG issues, was Battery on 200 HP Tubro 7A |
--> RV-List message posted by: "Ken Simmons" <ken@truckstop.com>
Mabye www.safeair1.com?
Ken
---------- Original Message ----------------------------------
From: "Glen Matejcek" <aerobubba@earthlink.net>
>--> RV-List message posted by: "Glen Matejcek" <aerobubba@earthlink.net>
>
>
>>Be careful that you consider the polar moment of inertia problem as well.
>>Think dumbbells vs bowling balls. Both have the cg in the center, but boy
>oh
>>
>>boy are the spin characteristics different.
>
>Excellent reminder, Gary! Along those lines, does anybody know whatever
>became of the fellows that used a 4" or so dia tube through the outboard
>LE lightening holes as aux fuel tanks? They were at OSH a couple years
>ago, trying to sell their idea. At the time they hadn't done any spin
>testing, and didn't seem to have considered roll coupling or the effects of
>maneuvering on the location of the fuel within the tanks...
>
>Glen Matejcek
>aerobubba@earthlink.net
>
>
Message 5
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| Subject: | Kens report on exceeding VNE at Alt. |
--> RV-List message posted by: "charles heathco" <cheathco@junct.com>
I found the report of dangers of exeeding VNE at Alt. very sobering. First I new
about it. I have unknowingly done it and was thinking about the time I was going
downhill from 13500' at redline (realized I was going to overshoot into the
Atl class B outer ring) I remember the 296 was showing close to 250mph, and
I thought that was a real plus. (6A with 150hp) Lucky for me, air was smooth
as glass, and I slowed down when I slipped under the outer ring. Now that I have
read Kens report, I wont be doing that again, Charlie Heathco
Message 6
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| Subject: | Re: CG issues, was Battery on 200 HP Tubro 7A |
--> RV-List message posted by: Kevin Horton <khorton01@rogers.com>
On 24 Dec 2005, at 09:09, Glen Matejcek wrote:
> --> RV-List message posted by: "Glen Matejcek"
> <aerobubba@earthlink.net>
>
>
>> Be careful that you consider the polar moment of inertia problem
>> as well.
>> Think dumbbells vs bowling balls. Both have the cg in the center,
>> but boy
> oh
>>
>> boy are the spin characteristics different.
>
> Excellent reminder, Gary! Along those lines, does anybody know
> whatever
> became of the fellows that used a 4" or so dia tube through the
> outboard
> LE lightening holes as aux fuel tanks? They were at OSH a couple
> years
> ago, trying to sell their idea. At the time they hadn't done any spin
> testing, and didn't seem to have considered roll coupling or the
> effects of
> maneuvering on the location of the fuel within the tanks...
It is instructive to look at how spins are treated in FAR 23
aircraft. There are two possibilities:
Spins are prohibited - one-turn spins are done in every configuration
(i.e. all combinations of flap, landing gear, CG, etc). This covers
off the case of an inadvertent stall, followed by incipient spin with
immediate pilot recovery.
Spins are approved - a full matrix of six-turn spin tests are done in
the configuration(s) that are approved for spins. One-turn spins are
done in the other configurations.
If aerobatics are approved, then the full range of spin tests must be
done, as there is a very real risk of ending up in a spin due to a
botched attempt at an aerobatic manoeuvre.
I believe the prudent RV owner of an aircraft with mods that might
affect the spin characteristics would do one of two things:
1. Do a full range of spin tests to be sure than any issues are found
during the flight test program when you are prepared to deal with
it. or,
2. Placard the aircraft as "Aerobatics and spins are prohibited". Do
a test program of one-turn spins only.
Note: It would be quite acceptable to placard "Aerobatics and spins
are prohibited with fuel in the outboard tanks", and then only do the
six-turn spin tests with those tanks empty. One turn spin tests
should be done with fuel in those tanks.
Some of the mods that people propose could have an adverse effect on
flight characteristics, including spins. This is OK, as long as the
builder does a full flight test program to determine whether the
handling is acceptable.
I get concerned when I read about builders "flying off the test
hours" as if there was no need to do much flight testing, and all
they had to do was log 25 or 40 hours so they could close off the
Phase 1 test program. If there are handling or performance problems,
the test phase is the time to find them. Then you can either modify
the aircraft to fix the problems, or determine a reduced flight or
weight/CG envelope to avoid the problems, or develop operational
techniques/limitations to avoid the problem areas. It is a lot safer
to find the problems when you are testing than it is to have them
catch you by surprise later.
Kevin Horton RV-8 (finishing kit)
Ottawa, Canada
http://www.kilohotel.com/rv8
Message 7
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| Subject: | Kens report on exceeding VNE at Alt. |
--> RV-List message posted by: "Dan Beadle" <Dan.Beadle@hq.InclineSoftworks.com>
I am still troubled by the Vne argument. For years, I have talked about
density of the air mass - it is molecules that affect the airplane, not
speed. At an altitude, more speed = more molecules. That would argue to
IAS, not TAS for the Vne limit.
An article this month in flying seems to support this thought. They talk
about the Vne on Columbia. They set it based at 260K. Flying discusses
why the decreasing Vne doesn't make sense at these sub-sonic speeds, but
is an artifact of setting Vne at or above the magic number of 260K.
Finally, the FAA chart, referenced in the article and shown in FAR 23,
shows IAS as the limiting factor, NOT TAS. (Seems like it should be CAS,
not IAS, but that is another argument).
I don't want the tail falling off, but I also don't want to artificially
limit the performance of the airframe. There are a lot of issues on
adding horsepower - cg shifts, more weight on the firewall (50# x 9G
limit - 450# more on motor mounts/firewall), etc.
Can anyone site any definitive references that would add more light on
the IAS/TAS issue for Vne. I am not sure Van's is right here.
Thanks
Dan Beadle
-----Original Message-----
From: owner-rv-list-server@matronics.com
[mailto:owner-rv-list-server@matronics.com] On Behalf Of charles heathco
Subject: RV-List: Kens report on exceeding VNE at Alt.
--> RV-List message posted by: "charles heathco" <cheathco@junct.com>
I found the report of dangers of exeeding VNE at Alt. very sobering.
First I new about it. I have unknowingly done it and was thinking about
the time I was going downhill from 13500' at redline (realized I was
going to overshoot into the Atl class B outer ring) I remember the 296
was showing close to 250mph, and I thought that was a real plus. (6A
with 150hp) Lucky for me, air was smooth as glass, and I slowed down
when I slipped under the outer ring. Now that I have read Kens report, I
wont be doing that again, Charlie Heathco
Message 8
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--> RV-List message posted by: "charles heathco" <cheathco@junct.com>
Wanted to say thanks to all the folks on this list who have shared helpfull info
with me this year, and am happy to say that all my problems have happened in
a good way, (catastrofic mag failure happened on the ground, Trailer tires blew
out durring move 1/4 mile from I-10 Exit near tire store, and so on.)Merry
Christmas to all, Charlie heathco. Do not archive
Message 9
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| Subject: | Re: Battery on 200 HP Tubro 7A |
--> RV-List message posted by: "Jeff Dowling" <shempdowling2@earthlink.net>
Well, it is EXPERIMENTAL.
Shemp/Jeff Dowling
RV-6A, N915JD
235 hours
Chicago/Louisville
----- Original Message -----
From: <UFOBUCK@aol.com>
Subject: Re: RV-List: Battery on 200 HP Tubro 7A
> --> RV-List message posted by: UFOBUCK@aol.com
>
> I think you should put the battery anywhere you want.
> You've not followed Van's recommendations relative to the powerplant and
> you
> damn sure shouldn't call it a RV-7A.
> I would hope the other RV-7 builders feel the same way. When the airplane
> bites you in the butt I don't think that they should get painted with the
> same
> brush of building and flying an unsound airplane.
> By the way I said "when" it bites you, not" if"'.
>
> BClary
> RV-6A finished, flown and sold
>
>
>
Message 10
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| Subject: | Re: Kens report on exceeding VNE at Alt. |
--> RV-List message posted by: Ron Lee <ronlee@pcisys.net>
At 08:06 AM 12/24/2005, you wrote:
>--> RV-List message posted by: "charles heathco" <cheathco@junct.com>
>
>I found the report of dangers of exeeding VNE at Alt. very sobering. First
>I new about it. I have unknowingly done it and was thinking about the time
>I was going downhill from 13500' at redline (realized I was going to
>overshoot into the Atl class B outer ring) I remember the 296 was showing
>close to 250mph, and I thought that was a real plus. (6A with 150hp) Lucky
>for me, air was smooth as glass, and I slowed down when I slipped under
>the outer ring. Now that I have read Kens report, I wont be doing that
>again, Charlie Heathco
Note that GPS gives you GROUNDSPEED so with a significant tailwind your
airspeed would be mucho lower.
Ron Lee
Message 11
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| Subject: | Re: CG issues, was Battery on 200 HP Tubro 7A |
--> RV-List message posted by: Mickey Coggins <mick-matronics@rv8.ch>
Kevin Horton wrote:
> I get concerned when I read about builders "flying off the test
> hours" as if there was no need to do much flight testing, and all
> they had to do was log 25 or 40 hours so they could close off the
> Phase 1 test program. If there are handling or performance problems,
> the test phase is the time to find them. Then you can either modify
> the aircraft to fix the problems, or determine a reduced flight or
> weight/CG envelope to avoid the problems, or develop operational
> techniques/limitations to avoid the problem areas. It is a lot safer
> to find the problems when you are testing than it is to have them
> catch you by surprise later.
Kevin, I agree completely. I'm looking forward to the
results of your Phase 1 testing, and "copying" all your
test cards. Your AFM is really outstanding, and has
saved me a lot of time.
--
Mickey Coggins
http://www.rv8.ch/
#82007 finishing
do not archive
Message 12
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| Subject: | Re: Battery on 200 HP Tubro 7A |
--> RV-List message posted by: <gmcjetpilot@yahoo.com>
Aubrey:
ALTITUDE:
First I think the call to NOT call your plane a RV is overkill in my
opinion. I like to let the facts speak for themselves. The Turbo only
makes more HP at high altitudes, and yes you must observe
speed limitations. This is not rocket science or a real big issue, but the
pilot needs to understand the effect of more power will have at higher
altitudes. RV's can, have and do fly in the FL200's anyway, And yes if
you are at FL180 you need to observe that your TAS does not exceed
your sea level (IAS) Vne limit Van specifies (or about 170 mph IAS).
This is conservative, but of course progressive flight test should be
done.
WEIGHT:
As far as weight 40 lbs for the turbo can be offset but a lighter prop
and YES moving the battery aft. You can always use a light
composite oil pan, put the Strobe pack in the back and so on.
W&B will NOT be an issue. However your gross weight will be
higher and thus you may be limited to solo aerobatics (I don't know
that but easy enough to check) and you will no doubt have less
payload capacity (if you keep the stock 1800 lb gross). Really there
are 6 cylinder RV-7/-8's out there. A turbo is a bolt on engine add on.
Many a STC has been issued for aftermarket turbos on factory planes.
There are plenty single engine factory planes that come in both
normally aspirated and turbo versions, planes like C210T, Mooney's
and Bonanza's. The airframes are virtually the same. I usually say
build it per plans, but I think the call to denounce your plane as NOT
RV-7/A is over kill. Yes 40 lbs is a lot of weight, but the aircraft was
designed around a heavy IO360 (200HP) engine. You might as well
say everyone who puts a Mazda, Subaru engine or modifies their
Lycoming engine or uses a clone Lycoming engine in their RV is not a
RV.
TURBO FOR ME?
NO, However if yes for you, you need to be aware of your TAS at
altitudes. My opinion is turbo charges are not a panicia for everything,
there are lots draw backs I am very aware of. The fact you need to
suck O2 and file IFR to take advantage the TURBO, limits it's use.
Also without a inter-cooler you are looking at decreasing efficiency and
TEMP limits, which will become you new limitation, engine
temperature. Even with an inter-cooler turbo piston engines are not a
slam dunk. If you want more high altitude power building a slightly
pumped up engine (high compression pistons, EI) will give you better
altitude performance. Keeping the wight down also helps. As it is now,
solo you can cruise right up near FL180 with out a turbo.
BATTERY:
Here is a list of CG/Empty weights of RV-7's at Dan's web site
http://www.rvproject.com/wab/
Using this info and doing some W&B you can play around with the
effect of the extra weight has and what effect the batterie'(s) will have
moving it (them) aft. You only have really two practical choices of
locations: Firewall (under cowl or cabin side) or behind the baggage
compartment. The other choice is to use a heavy battery or light
battery. My first choice would be stick with plans, but with all the turbo
stuff putting the battery on the cooler cabin side of the firewall will give
more room for the STUFF (inter cooler, large large oil cooler, lots of
hoses and ducts). Aft baggage is a pain and will add overall weight
and long battery cables, but it is doable.
HERE IS A PICTURE OF TURBO RV-8
http://img69.imageshack.us/img69/4687/image439ccea15c0c11d96hp.
jpg
If you want a turbo plan on very crowded cowl. This is a view of the oil
cooler (notice how big!). The inter-cooler is on the other side which
also gets air from a NACA scoop on the side of the cowl. Maintenance
will be more frequent and it will require more pilot attention and skill to
operate properly.
As far as insurance that is between you and the insurer. I know they
will want a IFR rated pilot and more time. When I was a CFI/II/MEI the
members of the club needed way more time to fly the turbo aircraft
models we had (Mooney/T210). Why? More pilots got into Weather
problems in a higher flying fast plane, thus the IFR rating was
required.
Bottom line is if you are able to take on a Turbo project you can do
some simple W&B exercices and figure where your battery ballast
needs to be.
Good Luck George
Match: #15 Message: #134873
From: "Aubrey" <aprice(at)fastspot.net>
Subject: Battery on 200 HP Tubro 7A
Date: Dec 22, 2005
I am building an RV7a with a IO 360 / 200 HP with Turbo Charger. The engine
is 40 pounds heavier plus the turbo. Should the battery be moved aft because
of the added weight.
Aubrey Price
N600AP
---------------------------------
Message 13
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| Subject: | Re: Kens report on exceeding VNE at Alt. |
--> RV-List message posted by: Kevin Horton <khorton01@rogers.com>
On 24 Dec 2005, at 10:32, Dan Beadle wrote:
> --> RV-List message posted by: "Dan Beadle"
> <Dan.Beadle@hq.InclineSoftworks.com>
>
> I am still troubled by the Vne argument. For years, I have talked
> about
> density of the air mass - it is molecules that affect the airplane,
> not
> speed. At an altitude, more speed = more molecules. That would
> argue to
> IAS, not TAS for the Vne limit.
>
> An article this month in flying seems to support this thought. They
> talk
> about the Vne on Columbia. They set it based at 260K. Flying
> discusses
> why the decreasing Vne doesn't make sense at these sub-sonic
> speeds, but
> is an artifact of setting Vne at or above the magic number of 260K.
>
> Finally, the FAA chart, referenced in the article and shown in FAR 23,
> shows IAS as the limiting factor, NOT TAS. (Seems like it should be
> CAS,
> not IAS, but that is another argument).
>
> I don't want the tail falling off, but I also don't want to
> artificially
> limit the performance of the airframe. There are a lot of issues on
> adding horsepower - cg shifts, more weight on the firewall (50# x 9G
> limit - 450# more on motor mounts/firewall), etc.
>
> Can anyone site any definitive references that would add more light on
> the IAS/TAS issue for Vne. I am not sure Van's is right here.
Van's pronouncements on VNE have me baffled as well.
From a practical point of view, there are many factors that the
designer and builder should consider when setting VNE.
Design issues:
Gust loads - air is not always smooth. For a given strength of
turbulence, the loads on the structure increase as the airspeed
increases. FAR 23 covers this by requiring that the structure be
strong enough to sustain a 25 ft/sec vertical gust when the aircraft
is flying at VNE. The assumed gusts have a very specific size and
shape. The higher the TAS the less time is required to penetrate the
gust, so the loads build faster. The higher the EAS, the higher the
loads. The result is that the gust loads increase with both EAS and
TAS.
Windscreen loads - the loads on the windscreen increase as the
airspeed increases. If the windscreen is flimsy enough, this may
limit VNE. This is probably not an issue with RVs, unless the
builder wants to increase VNE to a very large value. Windscreen
loads increase with EAS, which is close enough to CAS for speeds less
than 250 kt and altitudes lower than 10,000 ft.
Wing loads - divergence - if something causes the wing to twist nose
up slightly, the increased angle of attack causes the wing to create
more lift, which could cause it to twist nose up some more. If the
speed is high enough, this can cause a vicious cycle that leads to
wing failure. This is called divergence. This may limit VNE on some
aircraft. Wing divergence loads go up with EAS.
Bird strike - some aircraft have VNE reduced to ensure that collision
with a certain sized bird won't cause wing or tail structural failure.
Flutter - if you fly fast enough, you enter a region where flutter
may occur. There are many different types of flutter, and each type
has its own relationship to EAS or TAS. The latest information from
Van's seems to suggest that for his designs, he considers TAS as the
critical factor.
Flight test issues (i.e. something for the builder to determine):
It is possible that the aircraft handling qualities may deteriorate
as the speed increases. The stick force per g may become dangerously
low (this is a general statement, not aimed at RVs). It may be
necessary to reduce VNE to ensure that the handling is acceptable
inside the approved flight envelope.
Note - I am not a structural engineer. There are probably other
aspects that I have left out, and my description of the above aspects
is incomplete.
For a type certificated aircraft, the manufacturer is required to
specify VNE such that there are no structural, handling, etc problems
inside the approved flight envelope. For lower performance aircraft,
it is common to see VNE express as IAS, and that value is good no
matter the altitude. For higher performance aircraft, VNE (in IAS)
may decrease as the altitude increases.
I looked at the wording about VNE in my RV-8 builder's manual. There
isn't much there. VNE is mentioned as a marking to put on the
airspeed indicator, but there is no mention that VNE (in IAS) should
be reduced as the altitude is increased. It is perfectly reasonable
for a builder to interpret the information in the builder's manual as
suggesting that the recommended VNE in IAS is acceptable at all
altitudes.
What should we use as VNE for our RVs? Well, we don't have access to
all the information needed to answer that question. Only Van's has
the information on the structural design, and flutter, etc. Van
should provide some clear guidance. He shouldn't expect each builder
to do his own flutter ground and flight test program to determine how
VNE should vary with altitude. It may be necessary for him to
specify that the VNE in IAS is constant up to XXX ft altitude, then
it decreases by Y kt per thousand feet increase in altitude.
I'll be sending an e-mail to Van's on this subject.
Kevin Horton RV-8 (finishing kit)
Ottawa, Canada
http://www.kilohotel.com/rv8
Message 14
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| Subject: | Vortex Generators: one RV4 experience and cruise penalty discussion |
--> RV-List message posted by: "Mark Todd" <motodd@worldnet.att.net>
I posted VG data for my RV4 several years ago on this list but I don't
see it in the archives, so I'll summarize it briefly.
Testing was done with temporarily installed VG's so I accumulated before
and after data times two as carefully as I knew how as an amateur test
pilot without special instrumentation.
Bottom line is VG's placed at 10% of chord took 12% off the 1G stall
TAS. For those who do competition Sportsman acro in their RV's, VG's
make for some very nice differences, especially competition spins. As
already mentioned in this thread, dogfighting is significantly
different. When you have a 20% smaller turning radius than your
opponent, it is a pretty dissimilar fight. Assuming pilots with equal
skills and thrust/weight, the fight is usually over in two turns or so.
I'd encourage some consideration on the issue of cruise speed loss. By
cleaning up intersection drag at the wing root, some planes might
actually end up with less total drag at cruise when VG's are in place,
even though the VG's have got to be adding parasitic drag. I've heard
that it is not uncommon in some light twins with VG's to be faster in
cruise. I know I couldn't measure a significant difference at 160 kt
TAS cruise in my RV4 with my 10% of chord VG placement. In fact, my raw
data from flying many GPS wind triangles showed an average 0.5 kt
increase with VG's. One pilot, one airplane. Certainly not
statistically significant. As they say, your experience may vary.
Please remember that if you're trying to minimize drag penalties at
cruise airspeeds, you need to place the VG's at the point where the
airflow normally converts to turbulent from laminar at that cruise
airspeed. Such a VG placement is not going to maximize slow flight
effects. I wonder if some of the differing experiences out there with
VG's has to do with where the VG's are placed along the chord line. One
might expect a difference between, say, placement at 8 versus 10 percent
of chord!
Parasitic drag is parasitic drag and the faster you go or the further
forward you place the VG's, the more you're going to hurt the top end
speed. My data doesn't conflict with those who have measured reductions
in cruise speeds as long as they're cruising faster than my 160kt TAS or
have their VG placement at less than 10% of chord.
Mark
RV-4 KAWO
"Time: 08:27:09 AM PST US
From: <gmcjetpilot@yahoo.com>
Subject: RV-List: Re: Vortex Generators
--> RV-List message posted by: <gmcjetpilot@yahoo.com>
Yes it is hard to get accurate data. People who sell them will tell
you
all kind of things but here is where the NO FREE LUNCH rule comes
in.
You can expect about 3kts lower stall and about 3 kts lower, less
top speed:
Message 15
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| Subject: | Re: Kens report on exceeding VNE at Alt. |
--> RV-List message posted by: "Rob Prior (rv7)" <rv7@b4.ca>
On 10:02:40 2005-12-24 Kevin Horton <khorton01@rogers.com> wrote:
> It is perfectly reasonable
> for a builder to interpret the information in the builder's manual as
> suggesting that the recommended VNE in IAS is acceptable at all
> altitudes.
And this would be correct for any FAR23 certified aircraft. Your airframe
doesn't know how high it is, or what the air density is. It doesn't care.
It only knows what it thinks the airspeed is, and that number comes from
your indicated airspeed.
True airspeed is only useful for pilots, so they can plan their next fuel
stop. It has nothing to do with the structural capabilities of the
aircraft.
-Rob
(I didn't stay at a holiday inn express last night, but I am an
aeronautical engineer...)
Message 16
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| Subject: | Re: Kens report on exceeding VNE at Alt. |
--> RV-List message posted by: LessDragProd@aol.com
Better review your text books regarding flutter speed. It is related to
TAS, since air density influences airframe structural dampening.
Regardless of Ken's RVator article, Vne is an INDICATED airspeed.
The structural flutter speed is stated as a TRUE airspeed.
IMHO, Ken's article was trying to point out the two airspeeds cross over at
some altitude. However, they went to great extremes to NOT provide a flutter
speed. (Sometimes it's important to notice what wasn't written.)
Regards,
Jim Ayers
PS In the old days :-), RV-3's were flutter tested at 10% over Vne (Vne=210
mph ias) at around 10,000'.
When you are going to sit in the seat, there is a tendency to study the text
a little closer.
In a message dated 12/24/2005 10:35:27 AM Pacific Standard Time, rv7@b4.ca
writes:
--> RV-List message posted by: "Rob Prior (rv7)" <rv7@b4.ca>
On 10:02:40 2005-12-24 Kevin Horton <khorton01@rogers.com> wrote:
> It is perfectly reasonable
> for a builder to interpret the information in the builder's manual as
> suggesting that the recommended VNE in IAS is acceptable at all
> altitudes.
And this would be correct for any FAR23 certified aircraft. Your airframe
doesn't know how high it is, or what the air density is. It doesn't care.
It only knows what it thinks the airspeed is, and that number comes from
your indicated airspeed.
True airspeed is only useful for pilots, so they can plan their next fuel
stop. It has nothing to do with the structural capabilities of the
aircraft.
-Rob
(I didn't stay at a holiday inn express last night, but I am an
aeronautical engineer...)
Message 17
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|
| Subject: | Dynafocal motor mounts |
--> RV-List message posted by: "Vincent Osburn" <flyby41@earthlink.net>
Has anybody worn out their dynafocal motor mounts? I think mine are shot or
nearly so as I have begun to detect a buzzing vibration heretofore undetected.
Very light but reminds me of a dune buggy with solid motor mounts but still
very light. Under hood inspection seem OK except the mounts look stretched toward
that way in which you might expect them to stretch. Airplane flying since
92 with 900 TT. I didn't own it at the time but I think I remember the builder/
owner/ friend saying something about swapping them around once?
What was the bestest cheapest mount to replace them with. Any suggestions
or input appreciated.
Vince
Message 18
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|
)
| Subject: | Market value of our RVs (was battery location for 200 HP turbo |
7A
)
--> RV-List message posted by: "Stephen J. Soule" <SSoule@pfclaw.com>
Listers,
This development reminds me ... I often wonder where we can find a good
measure of the market value of our RVs. Every year I face this question when
I renew my insurance for my flying RV-6A. Any advice out there?
Trade-A-Plane shows me asking prices, but where can I find sale prices or
insurance settlement information about totaled RVs?
Stephen Soule in snowy Vermont
RV-6A N227RV
PS - I posted this yesterday, but it didn't go through. Forgive me if you've
already seen it.
-----Original Message-----
From: owner-rv-list-server@matronics.com
[mailto:owner-rv-list-server@matronics.com
<mailto:owner-rv-list-server@matronics.com> ] On Behalf Of RAS
Subject: Re: RV-List: Battery on 200 HP Tubro 7A
... you have sold on your RV6A,perhaps at
the going market value, therefore making profit,
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
<META NAME"Generator" CONTENT"MS Exchange Server version 5.5.2657.73">
Market value of our RVs (was battery location for 200 HP turbo 7A)
Listers,
This development reminds me ... I often wonder where we can find a good measure
of the market value of our RVs. Every year I face this question when I renew
my insurance for my flying RV-6A. Any advice out there? Trade-A-Plane shows me
asking prices, but where can I find sale prices or insurance settlement information
about totaled RVs?
Stephen Soule in snowy Vermont
RV-6A N227RV
PS - I posted this yesterday, but it didn't go through. Forgive me if you've already
seen it.
-----Original Message-----
From: owner-rv-list-server@matronics.com [mailto:owner-rv-list-server@matronics.com] On Behalf Of RAS
Subject: Re: RV-List: Battery on 200 HP Tubro 7A
... you have sold on your RV6A,perhaps at
the going market value, therefore making profit,=20
Message 19
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|
)
| Subject: | Market value of our RVs (was battery location for 200 HP turbo |
7A
)
--> RV-List message posted by: "Stephen J. Soule" <SSoule@pfclaw.com>
Listers,
This development reminds me ... I often wonder where we can find a good
measure of the market value of our RVs. Every year I face this question when
I renew my insurance for my flying RV-6A. Any advice out there?
Trade-A-Plane shows me asking prices, but where can I find sale prices or
insurance settlement information about totaled RVs?
Stephen Soule in snowy Vermont
RV-6A N227RV
PS - I posted this yesterday, but it didn't go through. Forgive me if you've
already seen it.
-----Original Message-----
From: owner-rv-list-server@matronics.com
[mailto:owner-rv-list-server@matronics.com
<mailto:owner-rv-list-server@matronics.com> ] On Behalf Of RAS
Subject: Re: RV-List: Battery on 200 HP Tubro 7A
... you have sold on your RV6A,perhaps at
the going market value, therefore making profit,
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
<META NAME"Generator" CONTENT"MS Exchange Server version 5.5.2657.73">
Market value of our RVs (was battery location for 200 HP turbo 7A)
Listers,
This development reminds me ... I often wonder where we can find a good measure
of the market value of our RVs. Every year I face this question when I renew
my insurance for my flying RV-6A. Any advice out there? Trade-A-Plane shows me
asking prices, but where can I find sale prices or insurance settlement information
about totaled RVs?
Stephen Soule in snowy Vermont
RV-6A N227RV
PS - I posted this yesterday, but it didn't go through. Forgive me if you've already
seen it.
-----Original Message-----
From: owner-rv-list-server@matronics.com [mailto:owner-rv-list-server@matronics.com] On Behalf Of RAS
Subject: Re: RV-List: Battery on 200 HP Tubro 7A
... you have sold on your RV6A,perhaps at
the going market value, therefore making profit,=20
Message 20
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|
| Subject: | Dynafocal motor mounts |
--> RV-List message posted by: "Dick DeCramer" <diesel@rconnect.com>
Vince...
Just bought a set from Vans....$55 for each motor mount plus $28.50 for
bolt kit. Total was $248.50 plus shipping. They are usually replaced at
engine major & in this case a accident after 1400 hours and a mild prop
strike but still a prop strike none the less.
> Subject: RV-List: Dynafocal motor mounts
>
> --> RV-List message posted by: "Vincent Osburn" <flyby41@earthlink.net>
>
> Has anybody worn out their dynafocal motor mounts? I think mine are
shot or nearly so as I have begun to detect a buzzing vibration heretofore
undetected. Very light but reminds me of a dune buggy with solid motor
mounts but still very light. Under hood inspection seem OK except the
mounts look stretched toward that way in which you might expect them to
stretch. Airplane flying since 92 with 900 TT. I didn't own it at the time
but I think I remember the builder/ owner/ friend saying something about
swapping them around once?
> What was the bestest cheapest mount to replace them with. Any
suggestions or input appreciated.
>
>
> Vince
>
>
Message 21
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| Subject: | Kens report on exceeding VNE at Alt. |
--> RV-List message posted by: "Dan Beadle" <Dan.Beadle@hq.InclineSoftworks.com>
Kevin, your thoughts seem to jive with mine. But Van's makes a big deal
about not over-engining a plane because of the Vne issue. You indicated
something about flutter and TAS below. It still seems to me that
anything aerodynamic would be IAS related. Do you have a source I could
dig into further?
I am building an RV8. I live at Lake Tahoe - so altitude is always an
issue. I am thinking IO360 + CS. My partner wants a turbo-normalized
engine. Maybe 180HP, but all the way up to mid teens. That sounds
pretty good to me, other than this Vne issue. I normally fly a
pressurized twin in the 20's. It would be nice to have plenty of pep to
get up to 15000' or so to cross the Sierras. I don't like messing with
O2, so we would use that as just a crossing altitude, then drop back
down and off of oxygen.
We are a ways from engine selection, but we want to avoid "test pilot"
as much as possible.
Thanks
Dan
-----Original Message-----
From: owner-rv-list-server@matronics.com
[mailto:owner-rv-list-server@matronics.com] On Behalf Of Kevin Horton
Subject: Re: RV-List: Kens report on exceeding VNE at Alt.
--> RV-List message posted by: Kevin Horton <khorton01@rogers.com>
On 24 Dec 2005, at 10:32, Dan Beadle wrote:
> --> RV-List message posted by: "Dan Beadle"
> <Dan.Beadle@hq.InclineSoftworks.com>
>
> I am still troubled by the Vne argument. For years, I have talked
> about
> density of the air mass - it is molecules that affect the airplane,
> not
> speed. At an altitude, more speed = more molecules. That would
> argue to
> IAS, not TAS for the Vne limit.
>
> An article this month in flying seems to support this thought. They
> talk
> about the Vne on Columbia. They set it based at 260K. Flying
> discusses
> why the decreasing Vne doesn't make sense at these sub-sonic
> speeds, but
> is an artifact of setting Vne at or above the magic number of 260K.
>
> Finally, the FAA chart, referenced in the article and shown in FAR 23,
> shows IAS as the limiting factor, NOT TAS. (Seems like it should be
> CAS,
> not IAS, but that is another argument).
>
> I don't want the tail falling off, but I also don't want to
> artificially
> limit the performance of the airframe. There are a lot of issues on
> adding horsepower - cg shifts, more weight on the firewall (50# x 9G
> limit - 450# more on motor mounts/firewall), etc.
>
> Can anyone site any definitive references that would add more light on
> the IAS/TAS issue for Vne. I am not sure Van's is right here.
Van's pronouncements on VNE have me baffled as well.
From a practical point of view, there are many factors that the
designer and builder should consider when setting VNE.
Design issues:
Gust loads - air is not always smooth. For a given strength of
turbulence, the loads on the structure increase as the airspeed
increases. FAR 23 covers this by requiring that the structure be
strong enough to sustain a 25 ft/sec vertical gust when the aircraft
is flying at VNE. The assumed gusts have a very specific size and
shape. The higher the TAS the less time is required to penetrate the
gust, so the loads build faster. The higher the EAS, the higher the
loads. The result is that the gust loads increase with both EAS and
TAS.
Windscreen loads - the loads on the windscreen increase as the
airspeed increases. If the windscreen is flimsy enough, this may
limit VNE. This is probably not an issue with RVs, unless the
builder wants to increase VNE to a very large value. Windscreen
loads increase with EAS, which is close enough to CAS for speeds less
than 250 kt and altitudes lower than 10,000 ft.
Wing loads - divergence - if something causes the wing to twist nose
up slightly, the increased angle of attack causes the wing to create
more lift, which could cause it to twist nose up some more. If the
speed is high enough, this can cause a vicious cycle that leads to
wing failure. This is called divergence. This may limit VNE on some
aircraft. Wing divergence loads go up with EAS.
Bird strike - some aircraft have VNE reduced to ensure that collision
with a certain sized bird won't cause wing or tail structural failure.
Flutter - if you fly fast enough, you enter a region where flutter
may occur. There are many different types of flutter, and each type
has its own relationship to EAS or TAS. The latest information from
Van's seems to suggest that for his designs, he considers TAS as the
critical factor.
Flight test issues (i.e. something for the builder to determine):
It is possible that the aircraft handling qualities may deteriorate
as the speed increases. The stick force per g may become dangerously
low (this is a general statement, not aimed at RVs). It may be
necessary to reduce VNE to ensure that the handling is acceptable
inside the approved flight envelope.
Note - I am not a structural engineer. There are probably other
aspects that I have left out, and my description of the above aspects
is incomplete.
For a type certificated aircraft, the manufacturer is required to
specify VNE such that there are no structural, handling, etc problems
inside the approved flight envelope. For lower performance aircraft,
it is common to see VNE express as IAS, and that value is good no
matter the altitude. For higher performance aircraft, VNE (in IAS)
may decrease as the altitude increases.
I looked at the wording about VNE in my RV-8 builder's manual. There
isn't much there. VNE is mentioned as a marking to put on the
airspeed indicator, but there is no mention that VNE (in IAS) should
be reduced as the altitude is increased. It is perfectly reasonable
for a builder to interpret the information in the builder's manual as
suggesting that the recommended VNE in IAS is acceptable at all
altitudes.
What should we use as VNE for our RVs? Well, we don't have access to
all the information needed to answer that question. Only Van's has
the information on the structural design, and flutter, etc. Van
should provide some clear guidance. He shouldn't expect each builder
to do his own flutter ground and flight test program to determine how
VNE should vary with altitude. It may be necessary for him to
specify that the VNE in IAS is constant up to XXX ft altitude, then
it decreases by Y kt per thousand feet increase in altitude.
I'll be sending an e-mail to Van's on this subject.
Kevin Horton RV-8 (finishing kit)
Ottawa, Canada
http://www.kilohotel.com/rv8
Message 22
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|
| Subject: | Fittings and sealants |
--> RV-List message posted by: "Bob Collins" <bcollinsrv7a@comcast.net>
I just want to double-check something on the use of sealant on various
plumbing fittings. This pertains to the admonishment not to use any sealant
on flared fittings. Am I correct that you're not talking about use the use
of sealant on the flare itself (I certainly get that), but you're saying you
don't use sealant on any of the threads to which the nut that holds the
flare into the fitting threads?
In other words, using the fuel valve as an example: you would use EZ Turn on
the threads of the fitting that screw into the valve assembly, but you do
not use any sealant on the threads at the other end of that fitting, where
the nut that holds the fuel line to the fuel valve threads?
Thanks for your patience and insight.
Bob
St. Paul
Message 23
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|
| Subject: | Re: Market value of our RVs (was battery location for 200 HP |
turbo 7A)
--> RV-List message posted by: "LarryRobertHelming" <lhelming@sigecom.net>
Think about it. The value of one plane to another will more than double in
value by the instruments installed. Your question is not that easily
answered. Your value could be actually what some one would buy it from you
for. Your insurance value is probably some thing you would want as a
minimum in the event it was totaled out by the insurace company which is
probably less than the first.
.
Indiana Larry, RV7 Tip Up SunSeeker 77 hours
"Please use the information and opinions I express with responsibility, and
at your own risk."
Achieving a certain level of success in life is only important if you can
finally enjoy the level you've reached after you've reached it.
L R Helming, who thought of it last.
----- Original Message -----
From: "Stephen J. Soule" <SSoule@pfclaw.com>
Subject: RV-List: Market value of our RVs (was battery location for 200 HP
turbo 7A)
> --> RV-List message posted by: "Stephen J. Soule" <SSoule@pfclaw.com>
>
> Listers,
>
> This development reminds me ... I often wonder where we can find a good
> measure of the market value of our RVs. Every year I face this question
> when
> I renew my insurance for my flying RV-6A. Any advice out there?
> Trade-A-Plane shows me asking prices, but where can I find sale prices or
> insurance settlement information about totaled RVs?
>
> Stephen Soule in snowy Vermont
> RV-6A N227RV
>
> PS - I posted this yesterday, but it didn't go through. Forgive me if
> you've
> already seen it.
>
> -----Original Message-----
> From: owner-rv-list-server@matronics.com
> [mailto:owner-rv-list-server@matronics.com
> <mailto:owner-rv-list-server@matronics.com> ] On Behalf Of RAS
> Sent: Friday, December 23, 2005 6:59 AM
> To: rv-list@matronics.com
> Subject: Re: RV-List: Battery on 200 HP Tubro 7A
>
> ... you have sold on your RV6A,perhaps at
> the going market value, therefore making profit,
>
> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
>
>
> <META NAME"Generator" CONTENT"MS Exchange Server version
> 5.5.2657.73">
> Market value of our RVs (was battery location for 200 HP turbo 7A)
>
>
> Listers,
>
>
> This development reminds me ... I often wonder where we can find a good
> measure of the market value of our RVs. Every year I face this question
> when I renew my insurance for my flying RV-6A. Any advice out there?
> Trade-A-Plane shows me asking prices, but where can I find sale prices or
> insurance settlement information about totaled RVs?
>
>
> Stephen Soule in snowy Vermont
>
> RV-6A N227RV
>
>
> PS - I posted this yesterday, but it didn't go through. Forgive me if
> you've already seen it.
>
>
> -----Original Message-----
>
> From: owner-rv-list-server@matronics.com
> [mailto:owner-rv-list-server@matronics.com] On Behalf Of RAS
>
> Sent: Friday, December 23, 2005 6:59 AM
>
> To: rv-list@matronics.com
>
> Subject: Re: RV-List: Battery on 200 HP Tubro 7A
>
>
> ... you have sold on your RV6A,perhaps at
>
> the going market value, therefore making profit,
>
>
>
Message 24
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|
| Subject: | Kens report on exceeding VNE at Alt. |
--> RV-List message posted by: "Alex Peterson" <alexpeterson@earthlink.net>
>
> And this would be correct for any FAR23 certified aircraft.
> Your airframe doesn't know how high it is, or what the air
> density is. It doesn't care.
> It only knows what it thinks the airspeed is, and that number
> comes from your indicated airspeed.
>
> True airspeed is only useful for pilots, so they can plan
> their next fuel stop. It has nothing to do with the
> structural capabilities of the aircraft.
>
> -Rob
> (I didn't stay at a holiday inn express last night, but I am
> an aeronautical engineer...)
I must respectfully disagree with some of what you wrote. The airframe does
indeed care about TAS, in two significant ways. One is dealing with
compressibility, which obviously doesn't apply to RV's. The other has to do
with what Ken wrote about. Flutter is a condition when some natural
frequency of a structure is excited by some external forces which happen to
be of the same frequency (this is a little simplified, but the idea is the
same). For example, say that some turbulence causes the horizontal
stabilizer to deflect upward by a small amount (this could be miniscule).
The amount of time which will pass between this event and when the same air
disturbance passes the elevator is inversely related to the TAS, not IAS. If
this period of time happens to be resonant with the natural frequency of the
horizontal stabilizer and elevator, it could begin being self exciting, with
ever increasing amplitude. The structure does not care how low the IAS
speed is, only what the TAS is. I suspect that there is some mitigation of
flutter risk as IAS drops due to lowering external forces, but what Ken
wrote makes complete sense.
Watching a slow motion video of HS/elevator flutter is quite alarming, and
most end with structural failure.
Alex Peterson
RV6-A N66AP 702 hours
Maple Grove, MN
Message 25
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| Subject: | Re: Fittings and sealants |
--> RV-List message posted by: linn walters <lwalters2@cfl.rr.com>
Bob Collins wrote:
>--> RV-List message posted by: "Bob Collins" <bcollinsrv7a@comcast.net>
>
>I just want to double-check something on the use of sealant on various
>plumbing fittings. This pertains to the admonishment not to use any sealant
>on flared fittings. Am I correct that you're not talking about use the use
>of sealant on the flare itself (I certainly get that), but you're saying you
>don't use sealant on any of the threads to which the nut that holds the
>flare into the fitting threads?
>
True.
>In other words, using the fuel valve as an example: you would use EZ Turn on
>the threads of the fitting that screw into the valve assembly, but you do
>not use any sealant on the threads at the other end of that fitting, where
>the nut that holds the fuel line to the fuel valve threads?
>
Not familiar with EZ turn, but if you're really bent on using a sealant
on fittings, only use it on tapered fittings, and leave 1 or two threads
on the end clean. That goes for both teflon tape, and teflon paste.
Aluminum fittings will seal much better than steel ones ...... or where
at least one surface is aluminum ...... probably due to the softness of
the aluminum Vs. the steel.
I don't use any sealant at all unless I have a leak to fix.
Linn
Do not archive
>
>Thanks for your patience and insight.
>
>Bob
>St. Paul
>
>
>
>
>
>
>
>
>
--
Message 26
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| Subject: | Re: Kens report on exceeding VNE at Alt. |
--> RV-List message posted by: Ron Lee <ronlee@pcisys.net>
>True airspeed is only useful for pilots, so they can plan their next fuel
>stop.
Some might question my piloting abilities but I don't worry much about
TAS. I use groundspeed for fuel stop considerations (using GPS).
Ron Lee
Do not archive
Message 27
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| Subject: | Re: Kens report on exceeding VNE at Alt. |
--> RV-List message posted by: rv6n6r@comcast.net
Just curious... how many RV accidents have there been that have been attributed
to flutter? Seems like it'd be one of those things that could be detected in
a post-crash investigation. I've never heard of one, and I KNOW some people out
there have exceeded VNE before.... could be a testament to the margins built
into Van's RVs? Don't remember if Ken mentioned it in his article either so forgive
me if this has already been answered.
Randall Henderson
RV-6
PS. Don't mind me, I'm just adding fuel to the fire...
;-)
do not archive
Message 28
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| Subject: | Re: Kens report on exceeding VNE at Alt. |
--> RV-List message posted by: "Olen Goodwin" <ogoodwin@comcast.net>
I've been following this thread, but may have missed something. My question
is: What is the Vne based on? Flutter or gust loads?
As for a turbo subjecting the airplane to higher airspeeds than safe, I'd
say that's the pilot rather than the engine. Almost all jet transports can
easily exceed Vne/Vmo any time the pilot wants to; the key is discipline.
Just operate the airplane within it's limitations, even if it's capable of
exceeding them.
The extra performance of a turbocharger (or big engine) is useful almost
anywhere in the western US or Canada operating off high altitude airports or
over high terrain. You just have to have the professionalism to limit your
speeds in accordance with the airplane's aerodynamic and structural limits.
Do not archive.
org
Message 29
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| Subject: | Time in the tanks, was Kens report on exceeding VNE at Alt. |
--> RV-List message posted by: Michael McGee <jmpcrftr@teleport.com>
At 15:57 2006-01-24, you wrote:
>--> RV-List message posted by: Ron Lee <ronlee@pcisys.net>
>
>
> >True airspeed is only useful for pilots, so they can plan their next fuel
> >stop.
>
>Some might question my piloting abilities but I don't worry much about
>TAS. I use groundspeed for fuel stop considerations (using GPS).
>
>Ron Lee
>
>Do not archive
Having landed without the convenience of an airport at one time I
find the clock is the best gauge of when to get gas. A high power
setting and a good head wind on one south bound trip from UAO put me
fueling up at SIY instead of RDD as planned (run those through the
GPS). When I put the caps on I had loaded all but 1/2 gallon of my
useable fuel (no it wasn't my RV-4). That was a BIG difference
between planned and actual.
Time is in the tanks (scaled for power setting), not miles. Don't
get me wrong, I like GPS, that's the only electronic navigation I have.
Mike McGee, RV-4 N996RV, O320-E2G, Hillsboro, OR
13B in gestation mode, RD-1C, EC-2
Message 30
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| Subject: | Re: Kens report on exceeding VNE at Alt. |
--> RV-List message posted by: sportav8r@aol.com
So do I run out and erase the redline marking from my ASI tomorrow? It only displays
IAS and is therefore worthless as an aid to avoiding flutter, no?
Not questioning your explanation of flutter, just the wisdom of painting red lines
on our ASI dials as required by the FAR's.
-Stormy
-----Original Message-----
From: Alex Peterson <alexpeterson@earthlink.net>
Subject: RE: RV-List: Kens report on exceeding VNE at Alt.
--> RV-List message posted by: "Alex Peterson" <alexpeterson@earthlink.net>
>
> And this would be correct for any FAR23 certified aircraft.
> Your airframe doesn't know how high it is, or what the air
> density is. It doesn't care.
> It only knows what it thinks the airspeed is, and that number
> comes from your indicated airspeed.
>
> True airspeed is only useful for pilots, so they can plan
> their next fuel stop. It has nothing to do with the
> structural capabilities of the aircraft.
>
> -Rob
> (I didn't stay at a holiday inn express last night, but I am
> an aeronautical engineer...)
I must respectfully disagree with some of what you wrote. The airframe does
indeed care about TAS, in two significant ways. One is dealing with
compressibility, which obviously doesn't apply to RV's. The other has to do
with what Ken wrote about. Flutter is a condition when some natural
frequency of a structure is excited by some external forces which happen to
be of the same frequency (this is a little simplified, but the idea is the
same). For example, say that some turbulence causes the horizontal
stabilizer to deflect upward by a small amount (this could be miniscule).
The amount of time which will pass between this event and when the same air
disturbance passes the elevator is inversely related to the TAS, not IAS. If
this period of time happens to be resonant with the natural frequency of the
horizontal stabilizer and elevator, it could begin being self exciting, with
ever increasing amplitude. The structure does not care how low the IAS
speed is, only what the TAS is. I suspect that there is some mitigation of
flutter risk as IAS drops due to lowering external forces, but what Ken
wrote makes complete sense.
Watching a slow motion video of HS/elevator flutter is quite alarming, and
most end with structural failure.
Alex Peterson
RV6-A N66AP 702 hours
Maple Grove, MN
Message 31
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| Subject: | Kens report on exceeding VNE at Alt. |
--> RV-List message posted by: "Dan Beadle" <Dan.Beadle@hq.InclineSoftworks.com>
Good explanation. The resonate frequency argument does make sense - and
that is based on TAS - not IAS.
Thanks
-----Original Message-----
From: owner-rv-list-server@matronics.com
[mailto:owner-rv-list-server@matronics.com] On Behalf Of Alex Peterson
Subject: RE: RV-List: Kens report on exceeding VNE at Alt.
--> RV-List message posted by: "Alex Peterson"
<alexpeterson@earthlink.net>
>
> And this would be correct for any FAR23 certified aircraft.
> Your airframe doesn't know how high it is, or what the air
> density is. It doesn't care.
> It only knows what it thinks the airspeed is, and that number
> comes from your indicated airspeed.
>
> True airspeed is only useful for pilots, so they can plan
> their next fuel stop. It has nothing to do with the
> structural capabilities of the aircraft.
>
> -Rob
> (I didn't stay at a holiday inn express last night, but I am
> an aeronautical engineer...)
I must respectfully disagree with some of what you wrote. The airframe
does
indeed care about TAS, in two significant ways. One is dealing with
compressibility, which obviously doesn't apply to RV's. The other has
to do
with what Ken wrote about. Flutter is a condition when some natural
frequency of a structure is excited by some external forces which happen
to
be of the same frequency (this is a little simplified, but the idea is
the
same). For example, say that some turbulence causes the horizontal
stabilizer to deflect upward by a small amount (this could be
miniscule).
The amount of time which will pass between this event and when the same
air
disturbance passes the elevator is inversely related to the TAS, not
IAS. If
this period of time happens to be resonant with the natural frequency of
the
horizontal stabilizer and elevator, it could begin being self exciting,
with
ever increasing amplitude. The structure does not care how low the IAS
speed is, only what the TAS is. I suspect that there is some mitigation
of
flutter risk as IAS drops due to lowering external forces, but what Ken
wrote makes complete sense.
Watching a slow motion video of HS/elevator flutter is quite alarming,
and
most end with structural failure.
Alex Peterson
RV6-A N66AP 702 hours
Maple Grove, MN
Message 32
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| Subject: | Kens report on exceeding VNE at Alt. |
--> RV-List message posted by: "Gordon or Marge Comfort" <gcomfo@tc3net.com>
-----Original Message-----
From: owner-rv-list-server@matronics.com
[mailto:owner-rv-list-server@matronics.com] On Behalf Of Kevin Horton
Subject: Re: RV-List: Kens report on exceeding VNE at Alt.
What should we use as VNE for our RVs? Well, we don't have access to
all the information needed to answer that question. Only Van's has
the information on the structural design, and flutter, etc. Van
should provide some clear guidance. He shouldn't expect each builder
to do his own flutter ground and flight test program to determine how
VNE should vary with altitude. It may be necessary for him to
specify that the VNE in IAS is constant up to XXX ft altitude, then
it decreases by Y kt per thousand feet increase in altitude.
I'll be sending an e-mail to Van's on this subject.
Kevin Horton RV-8 (finishing kit)
Ottawa, Canada
http://www.kilohotel.com/rv8
Kevin: Good luck with Van's. My efforts to extract useful information from
Ken Krueger have pretty much come to naught. Either he doesn't think we are
intelligent enough to understand or is not inclined to trouble himself.
With me, at least, he falls back on dogma without further amplification.
With regard to flutter, it would be great to have a good explanation of the
flutter margins that the various RV's possess. Ken used the -10 to
illustrate the principles he espoused but I don't know if the numbers he
used were to be taken literally or he was trying to frighten us into
compliance. I can grasp the connection between TAS and flutter even if I
can't defend it but to me there is still something wrong with the picture.
If the RV's presently flying had narrow flutter margins we should be hearing
about airframe failures that are not occuring. I know of one RV-4 that hit
270mph indicated in a maneuver that began at the base of a cumulus cloud
above surface elevations at 5000' and more. There was minor airframe damage
but no flutter. I tested my -4 to 200kt indicated at about 6000' in smooth
air and did not excite the controls. More recently I screwed up a maneuver
and saw about 205kt at about 4000' in air that was not smooth. No sign of
flutter.
How would one improve flutter margins? We balance ailerons to 100%. Would
heavier leading edge skins all the way to the tips help? Elevators are
balanced to 100% Stiffer stabilizer? How stiff? Higher design load factor
airframes? I would really like to know. Flight testing for flutter is
scary stuff and one must be prepared to try to evacuate a collapsing
airframe. I've been told of methods for mitigating the risk but still have
not found in myself the courage to seriously try it. Keep us posted, please.
Gordon Comfort
N363GC
Message 33
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| Subject: | Re: Fittings and sealants |
--> RV-List message posted by: "LARRY ADAMSON" <rvhi03@msn.com>
----- Original Message -----
From: Bob Collins
Subject: RV-List: Fittings and sealants
Since I've been in the HVAC business for 34 years, and too much experience with
gas lines and pipe threads, it's a fact that a threaded gas line fitting will leak
with just 4 oz. of natural gas pressure, which is the normal pressure of a
homes gas line, & no pipe thread sealer is used. I used thread sealer on all
of my tapered pipe thread fittings with exception to plastics. Oil lines, as well
as brakes.
I use a thread sealer that's compatible with about all petroleum products and oxygen,
and I would not feel comfortable without it.
Flared fittings should just be metal to metal.
--> RV-List message posted by: "Bob Collins" <bcollinsrv7a@comcast.net>
I just want to double-check something on the use of sealant on various
plumbing fittings. This pertains to the admonishment not to use any sealant
on flared fittings. Am I correct that you're not talking about use the use
of sealant on the flare itself (I certainly get that), but you're saying you
don't use sealant on any of the threads to which the nut that holds the
flare into the fitting threads?
In other words, using the fuel valve as an example: you would use EZ Turn on
the threads of the fitting that screw into the valve assembly, but you do
not use any sealant on the threads at the other end of that fitting, where
the nut that holds the fuel line to the fuel valve threads?
Message 34
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| Subject: | Time in the tanks |
--> RV-List message posted by: "Ed Holyoke" <bicyclop@pacbell.net>
A clock is good. A fuel totalizer is better. Read out the time to
waypoint on the GPS and compare it to the time till empty on the
totalizer then subtract 30 or 45 minutes for reserve. I've often used
this technique to change destinations when my planned fuel stop was
inaccessible due to weather or headwinds and comfortably got maximum
possible range out of the gas on board. Always landed with at least 40
minutes of gas left. The time till empty and fuel remaining are accurate
no matter what combination of power and mixture settings you've been
using. This is particularly handy when you've been forced to descend and
divert by weather and you're burning more gallons per hour than you
planned for or when winds aloft are different than forecast. A clock is
still necessary for keeping track of the tank in which the remaining
fuel resides, though.
Pax,
Ed Holyoke
-----Original Message-----
From: owner-rv-list-server@matronics.com
[mailto:owner-rv-list-server@matronics.com] On Behalf Of Michael McGee
Subject: RV-List: Time in the tanks, was Kens report on exceeding VNE at
Alt.
--> RV-List message posted by: Michael McGee <jmpcrftr@teleport.com>
At 15:57 2006-01-24, you wrote:
>--> RV-List message posted by: Ron Lee <ronlee@pcisys.net>
>
>
> >True airspeed is only useful for pilots, so they can plan their next
fuel
> >stop.
>
>Some might question my piloting abilities but I don't worry much about
>TAS. I use groundspeed for fuel stop considerations (using GPS).
>
>Ron Lee
>
>Do not archive
Having landed without the convenience of an airport at one time I
find the clock is the best gauge of when to get gas. A high power
setting and a good head wind on one south bound trip from UAO put me
fueling up at SIY instead of RDD as planned (run those through the
GPS). When I put the caps on I had loaded all but 1/2 gallon of my
useable fuel (no it wasn't my RV-4). That was a BIG difference
between planned and actual.
Time is in the tanks (scaled for power setting), not miles. Don't
get me wrong, I like GPS, that's the only electronic navigation I have.
Mike McGee, RV-4 N996RV, O320-E2G, Hillsboro, OR
13B in gestation mode, RD-1C, EC-2
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