Today's Message Index:
----------------------
1. 05:21 AM - Re: Bonding fiberglass to plexiglass (Greg McFarlane)
2. 05:56 AM - Re: Soundproofing (Greg McFarlane)
3. 06:35 AM - Re: V Speeds (Bill Watson)
4. 07:03 AM - Re: V Speeds (Linn Walters)
5. 07:29 AM - Re: Soundproofing (johngoodman)
6. 07:34 AM - Re: Re: Soundproofing (Ed Kranz)
7. 08:22 AM - Re: Bonding fiberglass to plexiglass (johngoodman)
8. 08:52 AM - Re: V Speeds (Bill Watson)
9. 09:01 AM - Re: V Speeds (Berck E. Nash)
10. 09:29 AM - Re: V Speeds (Linn Walters)
11. 09:41 AM - Re: V Speeds (Berck E. Nash)
12. 10:57 AM - Re: V Speeds (Jack Philips)
13. 05:22 PM - Re: V Speeds (Jesse Saint)
14. 06:03 PM - Re: V Speeds (Bob Turner)
15. 07:33 PM - Re: Bonding fiberglass to plexiglass (rvdave)
16. 09:32 PM - Re: Re: V Speeds (Kelly McMullen)
17. 11:04 PM - Re: V Speeds (Bob Turner)
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: | Re: Bonding fiberglass to plexiglass |
I had exactly the same result using West Systems Epoxy although prep did not include
cleaning with acetone. Just like you (although it looked great) I found
no adhesion to the Plexglass with my glass layup over the window to cabin top
intersection. When I questioned my West agent they were not at all surprised that
the bond had been unsuccessful. Turns out the only product that West recommends
for Plexglass is their G Flex. I have since like you peeled off all the
glass layup and have routed out around ALL windows and "reglued" with GFlex and
403 filler. Like a lot of 2seat RV builders I have previously used the recommended
epoxy 105/206 combo to bond windscreen fairings and they have apparently
been successful. However with the flatish RV10 side window experience I now
suspect that a lot of these windscreen lay ups have little adhesion to the Plexglass.
Because of the curve at the bottom of the windscreen the layup is very
tight on the screen and it's hard to see there is no adhesion, but again because
the layup is so tight against the screen it's not an issue. Cheers from
Western Australia
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=445297#445297
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: | Re: Soundproofing |
As Jesse has said, any air leakage around the door seals/hinges will encourage
airflow from the baggage V holes into the cabin, however those V holes are actually
for airflow OUT of the cabin. Not a good idea to block these holes up to
keep rear passengers ears warm as a potential build up of any Carbon Monoxide
will probably be the result. Cheers from Western Australia
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=445299#445299
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 |
|
A quick response to test my own basic understanding - Vne is always
expressed in TAS, Vstalls all in indicated. I think the physics behind
that is what creates the 'coffin corner' at high altitudes.
Experts, please correct and explain.
On 7/28/2015 12:05 AM, kearney wrote:
>
> Hi
>
> At KOSH I had a spirited discussion with a group of South Africans regarding flutter, IAS and TAS. The end result was a revisited Van's article on flutter that I had read many, many moons ago. (See http://vansaircraft.com/pdf/hp_limts.pdf)
>
> I also reviewed the RV-10 v-speeds published by Vans in the flight test doc
after reading he flutter document. In particular I was surprised to note that
the Vne published by Vans of 230 mph / 200 Kts was TAS and not IAS. Many of the
POH docs available on line quote a 200 KIAS value for Vne which, at higher
altitudes, could lead to a reduced flutter safety margin.
>
> I am assuming that all the other V speeds should be KIAS and not KTAS not that
there would be much of a difference except perhaps for the max maneuvering speed
/ max structural cruise speed.
>
> Is this correct or am I missing something here?
>
> Cheers
>
> Les
>
> Inquiring minds really need to know.
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=445292#445292
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
>
>
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 |
|
I'm no expert, but my take is that TAS Vne will relate to a finite
stress on the airframe, while the IAS stress will vary by temperature
and altitude. I think the Vne figure relates more to flutter and
airframe design limits rather than the 'coffin corner'. The 'coffin
corner' is going to be that area where the stall speed at altitude
becomes very close to the operating speed, and would be a function of
the aircraft aerodynamics and available power. I'm guessing that our
normally aspirated aircraft would get into the 'coffin corner' near it's
service ceiling ...... as excess lift and available power run out.
Linn
On 7/28/2015 9:32 AM, Bill Watson wrote:
>
> A quick response to test my own basic understanding - Vne is always
> expressed in TAS, Vstalls all in indicated. I think the physics
> behind that is what creates the 'coffin corner' at high altitudes.
>
> Experts, please correct and explain.
>
> On 7/28/2015 12:05 AM, kearney wrote:
>>
>> Hi
>>
>> At KOSH I had a spirited discussion with a group of South Africans
>> regarding flutter, IAS and TAS. The end result was a revisited Van's
>> article on flutter that I had read many, many moons ago. (See
>> http://vansaircraft.com/pdf/hp_limts.pdf)
>>
>> I also reviewed the RV-10 v-speeds published by Vans in the flight
>> test doc after reading he flutter document. In particular I was
>> surprised to note that the Vne published by Vans of 230 mph / 200 Kts
>> was TAS and not IAS. Many of the POH docs available on line quote a
>> 200 KIAS value for Vne which, at higher altitudes, could lead to a
>> reduced flutter safety margin.
>>
>> I am assuming that all the other V speeds should be KIAS and not KTAS
>> not that there would be much of a difference except perhaps for the
>> max maneuvering speed / max structural cruise speed.
>>
>> Is this correct or am I missing something here?
>>
>> Cheers
>>
>> Les
>>
>> Inquiring minds really need to know.
>>
>>
>>
>>
>> Read this topic online here:
>>
>> http://forums.matronics.com/viewtopic.php?p=445292#445292
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> -----
>> No virus found in this message.
>> Checked by AVG - www.avg.com
>>
>>
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
> 07/28/15
>
>
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: Soundproofing |
kearney wrote:
> Hi
>
> Since I posted this I started working through the VAF archives etc. I ended up
researching Abesco FP200 foam that I read about on the VAF forums.
>
> This would seem to be a good product to install under the floor pans as it is
an expanding fire stop foam and does have some noise damping properties as well.
The lightening holes would provide installation access. When cured it is a
very light foam.
>
> Has anyone on the list used this?
>
> As I understand it, one limitation is that it should not be used in places where
temps normally exceed 150-200C on an ongoing basis. Does anyone have any idea
as to what the skin temps are near the exhausts?
>
> Lastly, here is an interesting demo of the differences between fire-blocks vs fire-stops. https://www.youtube.com/watch?v=djB4dmfHhQk
>
> Cheers
>
> Les
Les,
I used several cans of Abesco FP200, and love it. I put it under all the floors.
The floors feel solid, are cool, and I assume there is sound reduction. The
best part is that it's a positive fire barrier. It's a great product.
John
--------
#40572 Phase One complete in 2011
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=445306#445306
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: Soundproofing |
I used Abesco FP200 under both the front and rear floorboards as I riveted
them in place.
It has quite a bit of force as it expands, and I'd recommend being careful
to either spray the foam under the floorboards before you rivet them down,
let it cure, trim the excess, and then install the floorboards, or if the
floors are already down, make sure you don't overfill the voids.
A nice side effect is that the floorboards have a very nice solid feel with
the foam in there.
On Mon, Jul 27, 2015 at 6:43 PM, Les Kearney <kearney@shaw.ca> wrote:
>
> Bob
>
> What did you do for the back pax?
>
> Cheers
>
> Les
>
> Sent from my iPhone
>
> > On Jul 27, 2015, at 17:04, Bob Turner <bobturner@alum.rpi.edu> wrote:
> >
> >
> > I'm with RV10Flyer; the best sound reduction/pound is from a good
> headset.
> > Start there, then decide if you need more. (My personal answer was "no".)
> >
> > However, I did have to do something about the draft in the back;
> passengers in the back had cold heads and hot feet.
> >
> > --------
> > Bob Turner
> > RV-10 QB
> >
> >
> >
> >
> > Read this topic online here:
> >
> > http://forums.matronics.com/viewtopic.php?p=445282#445282
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
>
>
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: | Re: Bonding fiberglass to plexiglass |
I think that I used a high quality isopropyl alcohol after sanding with 200 grit.
If I remember correctly, acetone was considered a no-no. Don't hold me to it,
it was a long time ago.
John
--------
#40572 Phase One complete in 2011
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=445308#445308
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 |
|
Amateur analysis sans Web research continued: The finite stress on the
airframe thing I hadn't considered. I was thinking about Vne relating
to flutter and flutter being TAS (speed with with air molecules pass
over surfaces) driven.
Then my recall of the 'coffin corner' issue be IAS stall speeds rising
with altitude to meet the TAS Vne. Go a bit slower and you fall out of
the sky, go a little faster and control surfaces begin to depart.
Doesn't apply to RV10 class stuff but rather high flying jets and
stuff. But now I'm having trouble making sense out that...
Bill "help!" Watson
On 7/28/2015 9:59 AM, Linn Walters wrote:
>
> I'm no expert, but my take is that TAS Vne will relate to a finite
> stress on the airframe, while the IAS stress will vary by temperature
> and altitude. I think the Vne figure relates more to flutter and
> airframe design limits rather than the 'coffin corner'. The 'coffin
> corner' is going to be that area where the stall speed at altitude
> becomes very close to the operating speed, and would be a function of
> the aircraft aerodynamics and available power. I'm guessing that our
> normally aspirated aircraft would get into the 'coffin corner' near
> it's service ceiling ...... as excess lift and available power run out.
> Linn
>
>
> On 7/28/2015 9:32 AM, Bill Watson wrote:
>>
>> A quick response to test my own basic understanding - Vne is always
>> expressed in TAS, Vstalls all in indicated. I think the physics
>> behind that is what creates the 'coffin corner' at high altitudes.
>>
>> Experts, please correct and explain.
>>
>> On 7/28/2015 12:05 AM, kearney wrote:
>>>
>>> Hi
>>>
>>> At KOSH I had a spirited discussion with a group of South Africans
>>> regarding flutter, IAS and TAS. The end result was a revisited Van's
>>> article on flutter that I had read many, many moons ago. (See
>>> http://vansaircraft.com/pdf/hp_limts.pdf)
>>>
>>> I also reviewed the RV-10 v-speeds published by Vans in the flight
>>> test doc after reading he flutter document. In particular I was
>>> surprised to note that the Vne published by Vans of 230 mph / 200
>>> Kts was TAS and not IAS. Many of the POH docs available on line
>>> quote a 200 KIAS value for Vne which, at higher altitudes, could
>>> lead to a reduced flutter safety margin.
>>>
>>> I am assuming that all the other V speeds should be KIAS and not
>>> KTAS not that there would be much of a difference except perhaps for
>>> the max maneuvering speed / max structural cruise speed.
>>>
>>> Is this correct or am I missing something here?
>>>
>>> Cheers
>>>
>>> Les
>>>
>>> Inquiring minds really need to know.
>>>
>>>
>>>
>>>
>>> Read this topic online here:
>>>
>>> http://forums.matronics.com/viewtopic.php?p=445292#445292
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> -----
>>> No virus found in this message.
>>> Checked by AVG - www.avg.com
>>>
>>>
>>
>>
>>
>>
>>
>>
>>
>> -----
>> No virus found in this message.
>> Checked by AVG - www.avg.com
>> 07/28/15
>>
>>
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
> 07/28/15
>
>
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 |
|
Close, but some corrections: For certified airplanes, Vne is an indicated
airspeed limit. In certified planes, you can safely dump the nose up to
redline on the airspeed indicator and not worry about flutter. The margins
are such that your true airspeed at Vne (indicated) are within limits even
at the service ceiling.
An RV-10 is not a certified plane, and Van's has kindly specified a Vne in
true airspeed so that we know where the margins are, rather than limiting
us to an indicated limit.
Now, "coffin's corner" is an entirely different situation. You can not get
anywhere near "coffin's corner" in an RV-10. Coffins corner means that
you're flying in a very narrow range between a stall and an overspeed. At
21,000 ft, you're going to stall at somewhere around 60mph IAS. Your
maximum safe speed (230mph TAS) is at worst around 160mph on a very hot
day. That gives you a 100mph margin between a stall and an overspeed
condition. Not a corner at all--that's a lot of margin. Coffin's corner
only really applies to jets. Most of the jets I've flown have somewhere
around 10-20 knot spread between stall and overspeed at their service
ceiling.
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 |
|
Awesome discussion!
High flying jets (read airliners ..... not the U2 ;-) ) have the power
to go faster way up there, and their speeds (I think) are computed as %
mach. They also have a thing called 'mach buffet' ..... and knowledge
of that is above my pay grade. However, for this discussion of RV-10
issues, you really have to work to get into the 'coffin corner' .... if
you really can.
I think some web searches may shed some 'technical light' on the
difference. Stall speed being IAS is probably due to the fact that's
what we see ..... and no conversion to TAS is necessary. I think all
the parameters that refer to flight in air would technically be more
accurate but harder to display without some knob twisting.
Linn ...... final wheel pants and cowl work. So much work with small gains.
On 7/28/2015 11:48 AM, Bill Watson wrote:
>
> Amateur analysis sans Web research continued: The finite stress on
> the airframe thing I hadn't considered. I was thinking about Vne
> relating to flutter and flutter being TAS (speed with with air
> molecules pass over surfaces) driven.
>
> Then my recall of the 'coffin corner' issue be IAS stall speeds rising
> with altitude to meet the TAS Vne. Go a bit slower and you fall out
> of the sky, go a little faster and control surfaces begin to depart.
> Doesn't apply to RV10 class stuff but rather high flying jets and
> stuff. But now I'm having trouble making sense out that...
>
> Bill "help!" Watson
>
> On 7/28/2015 9:59 AM, Linn Walters wrote:
>>
>> I'm no expert, but my take is that TAS Vne will relate to a finite
>> stress on the airframe, while the IAS stress will vary by temperature
>> and altitude. I think the Vne figure relates more to flutter and
>> airframe design limits rather than the 'coffin corner'. The 'coffin
>> corner' is going to be that area where the stall speed at altitude
>> becomes very close to the operating speed, and would be a function of
>> the aircraft aerodynamics and available power. I'm guessing that our
>> normally aspirated aircraft would get into the 'coffin corner' near
>> it's service ceiling ...... as excess lift and available power run out.
>> Linn
>>
>>
>> On 7/28/2015 9:32 AM, Bill Watson wrote:
>>>
>>> A quick response to test my own basic understanding - Vne is always
>>> expressed in TAS, Vstalls all in indicated. I think the physics
>>> behind that is what creates the 'coffin corner' at high altitudes.
>>>
>>> Experts, please correct and explain.
>>>
>>> On 7/28/2015 12:05 AM, kearney wrote:
>>>>
>>>> Hi
>>>>
>>>> At KOSH I had a spirited discussion with a group of South Africans
>>>> regarding flutter, IAS and TAS. The end result was a revisited
>>>> Van's article on flutter that I had read many, many moons ago. (See
>>>> http://vansaircraft.com/pdf/hp_limts.pdf)
>>>>
>>>> I also reviewed the RV-10 v-speeds published by Vans in the flight
>>>> test doc after reading he flutter document. In particular I was
>>>> surprised to note that the Vne published by Vans of 230 mph / 200
>>>> Kts was TAS and not IAS. Many of the POH docs available on line
>>>> quote a 200 KIAS value for Vne which, at higher altitudes, could
>>>> lead to a reduced flutter safety margin.
>>>>
>>>> I am assuming that all the other V speeds should be KIAS and not
>>>> KTAS not that there would be much of a difference except perhaps
>>>> for the max maneuvering speed / max structural cruise speed.
>>>>
>>>> Is this correct or am I missing something here?
>>>>
>>>> Cheers
>>>>
>>>> Les
>>>>
>>>> Inquiring minds really need to know.
>>>>
>>>>
>>>>
>>>>
>>>> Read this topic online here:
>>>>
>>>> http://forums.matronics.com/viewtopic.php?p=445292#445292
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> -----
>>>> No virus found in this message.
>>>> Checked by AVG - www.avg.com
>>>>
>>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> -----
>>> No virus found in this message.
>>> Checked by AVG - www.avg.com
>>> 07/28/15
>>>
>>>
>>
>>
>>
>>
>>
>>
>>
>> -----
>> No virus found in this message.
>> Checked by AVG - www.avg.com
>> 07/28/15
>>
>>
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
> 07/28/15
>
>
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 |
|
Here's what coffin's corner looks like on a PFD:
http://www.pbase.com/flying_dutchman/image/124628692
It's a pretty routine scenario for airliners as we try to fly as high as we
safely can to save on fuel. Not a lot of margin, and it's not a good idea
to hand-fly at those altitudes. Or to fly too close to thunderstorms.
Not a problem in an RV-10 as you just can't get high enough.
On Tue, Jul 28, 2015 at 10:25 AM, Linn Walters <flying-nut@cfl.rr.com>
wrote:
>
> Awesome discussion!
> High flying jets (read airliners ..... not the U2 ;-) ) have the power to
> go faster way up there, and their speeds (I think) are computed as % mach.
> They also have a thing called 'mach buffet' ..... and knowledge of that is
> above my pay grade. However, for this discussion of RV-10 issues, you
> really have to work to get into the 'coffin corner' .... if you really can.
>
> I think some web searches may shed some 'technical light' on the
> difference. Stall speed being IAS is probably due to the fact that's what
> we see ..... and no conversion to TAS is necessary. I think all the
> parameters that refer to flight in air would technically be more accurate
> but harder to display without some knob twisting.
> Linn ...... final wheel pants and cowl work. So much work with small
> gains.
>
> On 7/28/2015 11:48 AM, Bill Watson wrote:
>
>>
>> Amateur analysis sans Web research continued: The finite stress on the
>> airframe thing I hadn't considered. I was thinking about Vne relating to
>> flutter and flutter being TAS (speed with with air molecules pass over
>> surfaces) driven.
>>
>> Then my recall of the 'coffin corner' issue be IAS stall speeds rising
>> with altitude to meet the TAS Vne. Go a bit slower and you fall out of the
>> sky, go a little faster and control surfaces begin to depart. Doesn't
>> apply to RV10 class stuff but rather high flying jets and stuff. But now
>> I'm having trouble making sense out that...
>>
>> Bill "help!" Watson
>>
>> On 7/28/2015 9:59 AM, Linn Walters wrote:
>>
>>>
>>> I'm no expert, but my take is that TAS Vne will relate to a finite
>>> stress on the airframe, while the IAS stress will vary by temperature and
>>> altitude. I think the Vne figure relates more to flutter and airframe
>>> design limits rather than the 'coffin corner'. The 'coffin corner' is
>>> going to be that area where the stall speed at altitude becomes very close
>>> to the operating speed, and would be a function of the aircraft
>>> aerodynamics and available power. I'm guessing that our normally aspirated
>>> aircraft would get into the 'coffin corner' near it's service ceiling
>>> ...... as excess lift and available power run out.
>>> Linn
>>>
>>>
>>> On 7/28/2015 9:32 AM, Bill Watson wrote:
>>>
>>>>
>>>> A quick response to test my own basic understanding - Vne is always
>>>> expressed in TAS, Vstalls all in indicated. I think the physics behind
>>>> that is what creates the 'coffin corner' at high altitudes.
>>>>
>>>> Experts, please correct and explain.
>>>>
>>>> On 7/28/2015 12:05 AM, kearney wrote:
>>>>
>>>>>
>>>>> Hi
>>>>>
>>>>> At KOSH I had a spirited discussion with a group of South Africans
>>>>> regarding flutter, IAS and TAS. The end result was a revisited Van's
>>>>> article on flutter that I had read many, many moons ago. (See
>>>>> http://vansaircraft.com/pdf/hp_limts.pdf)
>>>>>
>>>>> I also reviewed the RV-10 v-speeds published by Vans in the flight
>>>>> test doc after reading he flutter document. In particular I was surprised
>>>>> to note that the Vne published by Vans of 230 mph / 200 Kts was TAS and not
>>>>> IAS. Many of the POH docs available on line quote a 200 KIAS value for Vne
>>>>> which, at higher altitudes, could lead to a reduced flutter safety margin.
>>>>>
>>>>> I am assuming that all the other V speeds should be KIAS and not KTAS
>>>>> not that there would be much of a difference except perhaps for the max
>>>>> maneuvering speed / max structural cruise speed.
>>>>>
>>>>> Is this correct or am I missing something here?
>>>>>
>>>>> Cheers
>>>>>
>>>>> Les
>>>>>
>>>>> Inquiring minds really need to know.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> Read this topic online here:
>>>>>
>>>>> http://forums.matronics.com/viewtopic.php?p=445292#445292
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> -----
>>>>> No virus found in this message.
>>>>> Checked by AVG - www.avg.com
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> -----
>>>> No virus found in this message.
>>>> Checked by AVG - www.avg.com
>>>> 07/28/15
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> -----
>>> No virus found in this message.
>>> Checked by AVG - www.avg.com
>>> 07/28/15
>>>
>>>
>>>
>>
>>
>>
>>
>>
>>
>> -----
>> No virus found in this message.
>> Checked by AVG - www.avg.com
>> 07/28/15
>>
>>
>>
>
>
Message 12
| 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 |
|
Mach Buffet I know a little bit about. It occurs when the airstream locally
exceeds the speed of sound, setting up small standing shock waves and flow
separation behind the shockwaves.
If a wing is flying at say .95 Mach, as the air flows over the curve of the
airfoil, it accelerates and may locally exceed Mach 1.0, , leading to
formation of a shock wave at that point. Air behind the shock wave is
subsonic and is prone to separating from the wing, leading to a buffet of
the control surfaces much like the buffeting that occurs before a stall.
As the wing accelerates, the shock formation moves further aft on the wing,
until at supersonic speeds it is at the trailing edge.
Jack Phillips
Smith Mountain Lake, Virginia
Beginning (finally) to rivet some components of the fuselage kit
-----Original Message-----
From: owner-rv10-list-server@matronics.com
[mailto:owner-rv10-list-server@matronics.com] On Behalf Of Linn Walters
Sent: Tuesday, July 28, 2015 12:26 PM
Subject: Re: RV10-List: V Speeds
Awesome discussion!
High flying jets (read airliners ..... not the U2 ;-) ) have the power to go
faster way up there, and their speeds (I think) are computed as % mach.
They also have a thing called 'mach buffet' ..... and knowledge of that is
above my pay grade. However, for this discussion of RV-10 issues, you
really have to work to get into the 'coffin corner' .... if you really can.
I think some web searches may shed some 'technical light' on the difference.
Stall speed being IAS is probably due to the fact that's what we see .....
and no conversion to TAS is necessary. I think all the parameters that
refer to flight in air would technically be more accurate but harder to
display without some knob twisting.
Linn ...... final wheel pants and cowl work. So much work with small gains.
On 7/28/2015 11:48 AM, Bill Watson wrote:
>
> Amateur analysis sans Web research continued: The finite stress on
> the airframe thing I hadn't considered. I was thinking about Vne
> relating to flutter and flutter being TAS (speed with with air
> molecules pass over surfaces) driven.
>
> Then my recall of the 'coffin corner' issue be IAS stall speeds rising
> with altitude to meet the TAS Vne. Go a bit slower and you fall out
> of the sky, go a little faster and control surfaces begin to depart.
> Doesn't apply to RV10 class stuff but rather high flying jets and
> stuff. But now I'm having trouble making sense out that...
>
> Bill "help!" Watson
>
> On 7/28/2015 9:59 AM, Linn Walters wrote:
>>
>> I'm no expert, but my take is that TAS Vne will relate to a finite
>> stress on the airframe, while the IAS stress will vary by temperature
>> and altitude. I think the Vne figure relates more to flutter and
>> airframe design limits rather than the 'coffin corner'. The 'coffin
>> corner' is going to be that area where the stall speed at altitude
>> becomes very close to the operating speed, and would be a function of
>> the aircraft aerodynamics and available power. I'm guessing that our
>> normally aspirated aircraft would get into the 'coffin corner' near
>> it's service ceiling ...... as excess lift and available power run out.
>> Linn
>>
>>
>> On 7/28/2015 9:32 AM, Bill Watson wrote:
>>>
>>> A quick response to test my own basic understanding - Vne is always
>>> expressed in TAS, Vstalls all in indicated. I think the physics
>>> behind that is what creates the 'coffin corner' at high altitudes.
>>>
>>> Experts, please correct and explain.
>>>
>>> On 7/28/2015 12:05 AM, kearney wrote:
>>>>
>>>> Hi
>>>>
>>>> At KOSH I had a spirited discussion with a group of South Africans
>>>> regarding flutter, IAS and TAS. The end result was a revisited
>>>> Van's article on flutter that I had read many, many moons ago. (See
>>>> http://vansaircraft.com/pdf/hp_limts.pdf)
>>>>
>>>> I also reviewed the RV-10 v-speeds published by Vans in the flight
>>>> test doc after reading he flutter document. In particular I was
>>>> surprised to note that the Vne published by Vans of 230 mph / 200
>>>> Kts was TAS and not IAS. Many of the POH docs available on line
>>>> quote a 200 KIAS value for Vne which, at higher altitudes, could
>>>> lead to a reduced flutter safety margin.
>>>>
>>>> I am assuming that all the other V speeds should be KIAS and not
>>>> KTAS not that there would be much of a difference except perhaps
>>>> for the max maneuvering speed / max structural cruise speed.
>>>>
>>>> Is this correct or am I missing something here?
>>>>
>>>> Cheers
>>>>
>>>> Les
>>>>
>>>> Inquiring minds really need to know.
>>>>
>>>>
>>>>
>>>>
>>>> Read this topic online here:
>>>>
>>>> http://forums.matronics.com/viewtopic.php?p=445292#445292
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> -----
>>>> No virus found in this message.
>>>> Checked by AVG - www.avg.com
>>>>
>>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> -----
>>> No virus found in this message.
>>> Checked by AVG - www.avg.com
>>> 07/28/15
>>>
>>>
>>
>>
>>
>>
>>
>>
>>
>> -----
>> No virus found in this message.
>> Checked by AVG - www.avg.com
>> 07/28/15
>>
>>
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
> 07/28/15
>
>
Message 13
| 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 |
|
It's my understanding that Vne should be in Calibrated Airspeed, which is ha
rd to come by and is somewhere between IAS and TAS, so to be conservative, V
an's has used TAS as the Vne number.
As was mentioned, certified airplanes probably have the safety margin and co
nversions between CAS and IAS to use IAS for Vne.
The "coffin corner" issue probably couldn't be approached without a high pow
er turbine. I doubt even a turbocharger could get it close unless maybe if i
t was a big turbo or set of turbos with inter coolers.
Jesse Saint
Saint Aviation, Inc.
jesse@saintaviation.com
C: 352-427-0285
F: 815-377-3694
Sent from my iPhone
> On Jul 28, 2015, at 11:55 AM, Berck E. Nash <flyboy@gmail.com> wrote:
>
> Close, but some corrections: For certified airplanes, Vne is an indicated a
irspeed limit. In certified planes, you can safely dump the nose up to redl
ine on the airspeed indicator and not worry about flutter. The margins are s
uch that your true airspeed at Vne (indicated) are within limits even at the
service ceiling.
>
> An RV-10 is not a certified plane, and Van's has kindly specified a Vne in
true airspeed so that we know where the margins are, rather than limiting u
s to an indicated limit.
>
> Now, "coffin's corner" is an entirely different situation. You can not ge
t anywhere near "coffin's corner" in an RV-10. Coffins corner means that yo
u're flying in a very narrow range between a stall and an overspeed. At 21,
000 ft, you're going to stall at somewhere around 60mph IAS. Your maximum s
afe speed (230mph TAS) is at worst around 160mph on a very hot day. That gi
ves you a 100mph margin between a stall and an overspeed condition. Not a c
orner at all--that's a lot of margin. Coffin's corner only really applies t
o jets. Most of the jets I've flown have somewhere around 10-20 knot spread
between stall and overspeed at their service ceiling.
>
>
3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3
D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3
D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3
D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3
D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>
Message 14
| 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 |
|
Calibrated airspeed is the same as indicated airspeed, if there are no instrument
or pitot-static errors.
Normally certified aircraft use CAS (or IAS) to specify Vne because this information
is available to the pilot. Many airplanes do not display TAS. I can only
imagine how few pilots would pull out an E6B as they nose over in a dive, to
calculate TAS from CAS.
I am also disappointed that Vans has chosen a very unorthodox approach in specifying
Vne in TAS, contrary to what most pilots were taught.
I would really like to know: is this number derived solely from ground vibration
tests? Did Vans test-dive the aircraft, and if so to what speed, and what altitude?
--------
Bob Turner
RV-10 QB
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=445322#445322
Message 15
| 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: Bonding fiberglass to plexiglass |
After reading up a little on the G Flex I think I will try it over the plex/ fiberglass
intersection, seems made more for dissimilar material bond. Thanks
--------
Dave Ford
RV6 for sale
RV10 building
Cadillac, MI
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=445323#445323
Message 16
| 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 |
|
I think Vans stated Vne as a TAS because it is based on the design flutter
speed, which IS a TAS, 200 kts or 230 mph for the -10. Flutter happens
based on the speed of the molecules going past the control surface and what
harmonics that induces in the control surface. Indicated is derived from
the pressure the molecules exert on the pitot tube, and thinner air is more
compressible so IAS goes down as altitude goes up.
As the manufacturer, you can either translate that TAS back to an indicated
airspeed, plus a fudge factor to account for density altitude differences,
or, if you have an EFIS, let it displace TAS as supplemental info and input
your Vne as a TAS. I think I will still subtract 5 kts as a safety margin,
in case the elevator or ailerons might flutter at lower speed with some
bird droppings or frost or whatever.
On Tue, Jul 28, 2015 at 5:59 PM, Bob Turner <bobturner@alum.rpi.edu> wrote:
>
> Calibrated airspeed is the same as indicated airspeed, if there are no
> instrument or pitot-static errors.
> Normally certified aircraft use CAS (or IAS) to specify Vne because this
> information is available to the pilot. Many airplanes do not display TAS. I
> can only imagine how few pilots would pull out an E6B as they nose over in
> a dive, to calculate TAS from CAS.
> I am also disappointed that Vans has chosen a very unorthodox approach in
> specifying Vne in TAS, contrary to what most pilots were taught.
> I would really like to know: is this number derived solely from ground
> vibration tests? Did Vans test-dive the aircraft, and if so to what speed,
> and what altitude?
>
> --------
> Bob Turner
> RV-10 QB
>
>
Message 17
| 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 |
|
[quote="Kelly McMullen"]I think Vans stated Vne as a TAS because it is based on
the design flutter speed, which IS a TAS, 200 kts or 230 mph for the -10. Flutter
happens based on the speed of the molecules going past the control surface
and what harmonics that induces in the control surface. Indicated is derived
from the pressure the molecules exert on the pitot tube, and thinner air is more
compressible so IAS goes down as altitude goes up.
As the manufacturer, you can either translate that TAS back to an indicated airspeed,
plus a fudge factor to account for density altitude differences, or, if
you have an EFIS, let it displace TAS as supplemental info and input your Vne
as a TAS. I think I will still subtract 5 kts as a safety margin, in case the
elevator or ailerons might flutter at lower speed with some bird droppings or
frost or whatever.
On Tue, Jul 28, 2015 at 5:59 PM, Bob Turner wrote:
>
> Calibrated airspeed is the same as indicated airspeed, if there are no instrument
or pitot-static errors.
> Normally certified aircraft use CAS (or IAS) to specify Vne because this information
is available to the pilot. Many airplanes do not display TAS. I can only
imagine how few pilots would pull out an E6B as they nose over in a dive,
to calculate TAS from CAS.
> I am also disappointed that Vans has chosen a very unorthodox approach in specifying
Vne in TAS, contrary to what most pilots were taught.
> I would really like to know: is this number derived solely from ground vibration
tests? Did Vans test-dive the aircraft, and if so to what speed, and what
altitude?
>
> --------
> Bob Turner
> RV-10 QB
>
> [b]
If only the world was this simple. There are many different flutter modes possible.
And they scale differently. For some the onset of flutter depends only on
TAS. For others, the onset depends on the product of TAS and the square root
of density - indicated airspeed. Still other modes have a density-airspeed scaling
which is in between these two. And which mode is excited at any given time
depends on the stiffness of the airframe part involved, etc. It really is as
much art as science. But to say only TAS is important is an over simplification.
--------
Bob Turner
RV-10 QB
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=445325#445325
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! --
|