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sarg314(at)gmail.com
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 Posted: Wed Jun 02, 2010 9:40 pm Post subject: some approx V speeds |
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Anticpating the first flight of my RV-6A, can some one tell me typical Vx and Vy, best angle of glide speed, and Va for these planes. Â I can refine them after it is flying, but I'd like to have some idea of what to expect to start with.
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Tom Sargent
[quote][b]
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Vanremog(at)aol.com
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| Posted: Wed Jun 02, 2010 10:10 pm Post subject: some approx V speeds |
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Try out my POH for that and more.
N1GV (RV-6A Flying 944TTAE Silicon Valley, CA)
Ya'know this reminds me very little of the time I wired my tinfoil hat in series with the output of an early 1990's vintage Sovtek MIG-100 amplifier, detuned the B string of my bass a few sonts short of 60Hz Dinah Moe HUMM, slathered the strings with braunschweiger and turned the cats loose upon it. Taken altogether, synergistically and copacetically, the net effect was nothing short of...thrilling.
In a message dated 6/2/2010 10:41:24 P.M. Pacific Daylight Time, sarg314(at)gmail.com writes:
| Quote: | Anticpating the first flight of my RV-6A, can some one tell me typical Vx and Vy, best angle of glide speed, and Va for these planes. I can refine them after it is flying, but I'd like to have some idea of what to expect to start with.
--
Tom Sargent
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ist href="http://www.matronics.com/Navigator?RV-List">http://www.matronics.com/Navigator?RV-List
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tp://forums.matronics.com/">http://forums.matronics.com
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href="http://www.matronics.com/contribution">http://www.matronics.com/contribution
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kboatright1(at)comcast.ne
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| Posted: Thu Jun 03, 2010 2:59 am Post subject: some approx V speeds |
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Thomas, which engine and prop do you have? Whether you have fixed pitch or constant speed prop makes a difference.
[quote] ---
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sarg314(at)gmail.com
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| Posted: Thu Jun 03, 2010 5:43 am Post subject: some approx V speeds |
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Kyle:I have a fixed pitch Catto prop and an IO-360-B2B.
On Thu, Jun 3, 2010 at 3:57 AM, Kyle Boatright <kboatright1(at)comcast.net (kboatright1(at)comcast.net)> wrote:
| Quote: | Thomas, which engine and prop do you have? Whether you have fixed pitch or constant speed prop makes a difference.
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Tom Sargent
[quote][b]
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Robin(at)PaintTheWeb.com
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| Posted: Thu Jun 03, 2010 8:52 am Post subject: some approx V speeds |
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Tom, This was my kneepad checklist when flying my 6A. Hope it helps. Note all speeds in MPH.
Robin
From: owner-rv-list-server(at)matronics.com (owner-rv-list-server(at)matronics.com) [mailto:owner-rv-list-server(at)matronics.com (owner-rv-list-server(at)matronics.com)] On Behalf Of thomas sargent
Sent: Thursday, June 03, 2010 6:44 AM
To: rv-list(at)matronics.com (rv-list(at)matronics.com)
Subject: Re: some approx V speeds
Kyle:
I have a fixed pitch Catto prop and an IO-360-B2B.
On Thu, Jun 3, 2010 at 3:57 AM, Kyle Boatright <kboatright1(at)comcast.net (kboatright1(at)comcast.net)> wrote:
Thomas, which engine and prop do you have? Whether you have fixed pitch or constant speed prop makes a difference.
--
Tom Sargent
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Use the Matronics List Features Navigator to browse[/b][/b] |
Day Browse, Chat, FAQ,[/b]w.matronics.com/Navigator?RV-List">http://www.matronics.com/Navigator?RV-Li
=====================< - MATRONICS WEB FORUMS -[/b][/quote] m">http://forums.matronics.com[/b][/quote] -Matt Dralle, List A; http://www.matronics.com/contribution[/b][/quote] =======================[/b] [/quote]
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HCRV6(at)comcast.net
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| Posted: Fri Jun 04, 2010 12:09 pm Post subject: some approx V speeds |
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Please explain:
Whether you have fixed pitch or constant speed prop makes a difference.
Harry Crosby
RV-6 N16CX, 693 hours
[quote][b]
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sarg314(at)gmail.com
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| Posted: Fri Jun 04, 2010 12:38 pm Post subject: some approx V speeds |
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Yes. I have a fixed pitch prop and a 180hp IO-360-B2B
On Fri, Jun 4, 2010 at 1:08 PM, <HCRV6(at)comcast.net (HCRV6(at)comcast.net)> wrote:
| Quote: | Please explain:
Whether you have fixed pitch or constant speed prop makes a difference.
Harry Crosby
RV-6 N16CX, 693 hours
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--
Tom Sargent
[quote][b]
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Ed Anderson
Joined: 10 Jan 2006
Posts: 475
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| Posted: Fri Jun 04, 2010 3:42 pm Post subject: some approx V speeds |
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Harry,
When I first did my airspeed checks with my fixed pitch prop RV-6A, I couldn’t get anywhere near the performance/airspeed figures that Van quoted. It turns out his figures are for engines with a constant speed prop.
My best climb speed Vy turns out to be 120 MPH IAS, considerably higher than the Van’s figure.
I’m sure there is someone out there that can give you a more understandable explanation – but it goes something like this.
Here is how I see it – with a constant speed prop, you can get more HP at slow airspeeds by making the pitch finer producing less load on the engine, which results in more RPM which results in more HP. When you are discussing climb it’s the EXTRA HP above that required to maintain level flight than causes you to climb. If you can increase your HP above that necessary for level flight, you can increase your climb rate at any airspeed (well, just about)..
With a fixed pitch prop, you have the maximum load on the prop and therefore the engine at slower airspeeds during climb-out, that keeps the rpm lower and therefore HP down compared to a constant speed prop. Therefore, in order to get more climb you need to produce more HP, with a fixed pitch prop you do that by flying a higher airspeed unloading the prop and engine a bit thereby permitting more rpm and HP and higher climb rate.
Ed
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson(at)carolina.rr.com
http://www.andersonee.com
http://www.dmack.net/mazda/index.html
http://www.flyrotary.com/
http://members.cox.net/rogersda/rotary/configs.htm#N494BW
http://www.rotaryaviation.com/Rotorhead%20Truth.htm[url=http://www.dmack.net/mazda/index.html][/url]
From: owner-rv-list-server(at)matronics.com [mailto:owner-rv-list-server(at)matronics.com] On Behalf Of HCRV6(at)comcast.net
Sent: Friday, June 04, 2010 4:09 PM
To: rv-list(at)matronics.com
Subject: Re: some approx V speeds
Please explain:
Whether you have fixed pitch or constant speed prop makes a difference.
Harry Crosby
RV-6 N16CX, 693 hours
| Quote: | | http://www.matronics.com/Navigator?RV-List |
0123456789
[quote][b]
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_________________
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com |
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khorton01(at)rogers.com
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| Posted: Fri Jun 04, 2010 4:39 pm Post subject: some approx V speeds |
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I was messing around a few months ago, making some charts to illustrate a magazine article on climb performance that I intend to finish someday. I used the combination of CAFE Foundation drag vs speed data for the RV-6A, Lycoming O-360 power charts and some Hartzell prop efficiency maps. I used that data to predict climb performance at various altitudes and speeds. I didn't have any fixed pitch prop efficiency data, so I used the Hartzell data, but forced it to use the same pitch for all conditions. The pitch was selected to give 2700 rpm at full throttle at 8000 ft.
The attached chart shows how Vx and Vy are predicted to vary with altitude for both fixed pitch and constant speed props. You will note that Vx and Vy are quite a bit faster with fixed pitch props, as the rpm and power increase as the airspeed is increased. You will also note that there is a significant variation of Vx and Vy with altitude.
I caution that this is a very crude prediction. It may not match the actual performance at all, so use at your own risk. It is interesting to note that the predicted fixed pitch Vy at sea level (105 kt, or 121 mph) is close to what Ed found. That may be blind luck.
Kevin Horton
Ottawa, Canada
On 04/06/10 07:41 PM, Ed Anderson wrote: | Quote: | v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} <![endif]--> st1\:*{behavior:url(#default#ieooui) } <![endif]-->
Harry,
When I first did my airspeed checks with my fixed pitch prop RV-6A, I couldn’t get anywhere near the performance/airspeed figures that Van quoted. It turns out his figures are for engines with a constant speed prop.
My best climb speed Vy turns out to be 120 MPH IAS, considerably higher than the Van’s figure.
I’m sure there is someone out there that can give you a more understandable explanation – but it goes something like this.
Here is how I see it – with a constant speed prop, you can get more HP at slow airspeeds by making the pitch finer producing less load on the engine, which results in more RPM which results in more HP. When you are discussing climb it’s the EXTRA HP above that required to maintain level flight than causes you to climb. If you can increase your HP above that necessary for level flight, you can increase your climb rate at any airspeed (well, just about)..
With a fixed pitch prop, you have the maximum load on the prop and therefore the engine at slower airspeeds during climb-out, that keeps the rpm lower and therefore HP down compared to a constant speed prop. Therefore, in order to get more climb you need to produce more HP, with a fixed pitch prop you do that by flying a higher airspeed unloading the prop and engine a bit thereby permitting more rpm and HP and higher climb rate.
Ed
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson(at)carolina.rr.com (eanderson(at)carolina.rr.com)
http://www.andersonee.com
http://www.dmack.net/mazda/index.html
http://www.flyrotary.com/
http://members.cox.net/rogersda/rotary/configs.htm#N494BW
http://www.rotaryaviation.com/Rotorhead%20Truth.htm
From: owner-rv-list-server(at)matronics.com (owner-rv-list-server(at)matronics.com) [mailto:owner-rv-list-server(at)matronics.com (owner-rv-list-server(at)matronics.com)] On Behalf Of HCRV6(at)comcast.net (HCRV6(at)comcast.net)
Sent: Friday, June 04, 2010 4:09 PM
To: rv-list(at)matronics.com (rv-list(at)matronics.com)
Subject: Re: RV-List: some approx V speeds
Please explain:
Whether you have fixed pitch or constant speed prop makes a difference.
Harry Crosby
RV-6 N16CX, 693 hours
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http://www.matronics.com/Navigator?RV-List |
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HCRV6(at)comcast.net
Guest
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| Posted: Sun Jun 06, 2010 12:24 pm Post subject: some approx V speeds |
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Ed,
Thanks for that. Without giving it much thought (make that any thought) my reaction was, what does it matter what kind of prop? Obviously it does as soon as one recognizes the effect of airspeed/RPM on HP with the fixed pitch props.
My experience is consistent with your observation, at 120 MPH my Catto prop allows me to climb with any of my buddies with CS props. They always get a bit of a jump on me at takeoff but as soon as I accelerate to 120 to 130 I can catch up.
Harry Crosby
RV-6 N16CX, 695 hours
---
| | - The Matronics RV-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV-List |
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Ed Anderson
Joined: 10 Jan 2006
Posts: 475
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| Posted: Sun Jun 06, 2010 2:51 pm Post subject: some approx V speeds |
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Welcome, Harry.
Yeah, I really thought I had a dog at first, because I couldn’t match Van’s performance numbers – just the wrong comparison in my case {:>).
There are certainly benefits to having a C/S on take off – however, for cost and simplicity reasons, I have not regretted staying fixed pitch.
I swing a 74x 88 Performance Wood Prop which takes all the right rudder I have in my 6A to keep it on our 35’ wide runway, in fact until I hit around 40 mph,
there is not sufficient rudder authority. Take off performance is great, but I still need to hit 120 MPH to get best rate of climb.
Now if I had to fly up a mountain side after take off – I might sing a different tune {:>)
ed
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson(at)carolina.rr.com
http://www.andersonee.com
http://www.dmack.net/mazda/index.html
http://www.flyrotary.com/
http://members.cox.net/rogersda/rotary/configs.htm#N494BW
http://www.rotaryaviation.com/Rotorhead%20Truth.htm[url=http://www.dmack.net/mazda/index.html][/url]
From: owner-rv-list-server(at)matronics.com [mailto:owner-rv-list-server(at)matronics.com] On Behalf Of HCRV6(at)comcast.net
Sent: Sunday, June 06, 2010 4:24 PM
To: rv-list(at)matronics.com
Subject: Re: some approx V speeds
Ed,
Thanks for that. Without giving it much thought (make that any thought) my reaction was, what does it matter what kind of prop? Obviously it does as soon as one recognizes the effect of airspeed/RPM on HP with the fixed pitch props.
My experience is consistent with your observation, at 120 MPH my Catto prop allows me to climb with any of my buddies with CS props. They always get a bit of a jump on me at takeoff but as soon as I accelerate to 120 to 130 I can catch up.
Harry Crosby
RV-6 N16CX, 695 hours
---
| | - The Matronics RV-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV-List |
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_________________
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com |
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billoves2fly(at)yahoo.com
Guest
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| Posted: Tue Jun 08, 2010 12:41 pm Post subject: some approx V speeds |
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From: "HCRV6(at)comcast.net" <HCRV6(at)comcast.net>
To: rv-list(at)matronics.com
Sent: Sun, June 6, 2010 3:23:32 PM
Subject: Re: some approx V speeds
p {margin:0;} Ed,
Thanks for that. Without giving it much thought (make that any thought) my reaction was, what does it matter what kind of prop? Obviously it does as soon as one recognizes the effect of airspeed/RPM on HP with the fixed pitch props.
My experience is consistent with your observation, at 120 MPH my Catto prop allows me to climb with any of my buddies with CS props. They always get a bit of a jump on me at takeoff but as soon as I accelerate to 120 to 130 I can catch up.
Harry Crosby
RV-6 N16CX, 695 hours
---
| | - The Matronics RV-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV-List |
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