Topics

Baggage pods - test flying

Dave
 

Does anyone have a test flying protocol for baggage pods to use during phase one testing?

I have the excellent Kevin Walsh document to adapt for my Long-EZ.
I'll be using Dale's 'Cozy size pods' for my Long-EZ build.

Dave
Flying LE VH-JZE and building
LE VH-XEZ


--
*********************************************************
David Berenholtz, Director
Southside Industries (Aust) Pty.Ltd.
P.O. Box 255 Black Rock Vic 3193 Australia

voice: + 61 3 9598 3000
email:   335dave@...
*********************************************************

Marc J. Zeitlin
 

Dave Berenholz wrote:

Does anyone have a test flying protocol for baggage pods to use during phase one testing?
I have the excellent Kevin Walsh document to adapt for my Long-EZ.

Assuming you follow Kevin's document, theoretically you'd need to repeat a substantial # of the tests both without and then with pods installed. These would include (but are probably not limited to) stall tests, climb tests, glide tests, stability tests, and flutter tests. Basically, anything that the aerodynamics and weight distribution of the pods might affect.

Most people don't do this when installing pods, of course, but most people seem not to do much in the way of testing in Phase I - they fly around in circles for 40 hours at a mid-CG, mid-weight condition and then call it good. Very disappointing. Be better than that.

--
Marc J. Zeitlin                      marc_zeitlin@...
                                            http://www.cozybuilders.org/
Copyright © 2019                     Burnside Aerospace

Tony Rothwell
 

Hi Dave, talk to Chris Burns in Bowral.  Tony 


On Sat., 7 Dec. 2019, 06:59 Dave, <335dave@...> wrote:
Does anyone have a test flying protocol for baggage pods to use during phase one testing?

I have the excellent Kevin Walsh document to adapt for my Long-EZ.
I'll be using Dale's 'Cozy size pods' for my Long-EZ build.

Dave
Flying LE VH-JZE and building
LE VH-XEZ


--
*********************************************************
David Berenholtz, Director
Southside Industries (Aust) Pty.Ltd.
P.O. Box 255 Black Rock Vic 3193 Australia

voice: + 61 3 9598 3000
email:   335dave@...
*********************************************************

Tony Rothwell
 

Chris Byrne.... Damn spell check.


On Sat., 7 Dec. 2019, 11:50 Tony Rothwell via Groups.Io, <tony13rothwell=gmail.com@groups.io> wrote:
Hi Dave, talk to Chris Burns in Bowral.  Tony 

On Sat., 7 Dec. 2019, 06:59 Dave, <335dave@...> wrote:
Does anyone have a test flying protocol for baggage pods to use during phase one testing?

I have the excellent Kevin Walsh document to adapt for my Long-EZ.
I'll be using Dale's 'Cozy size pods' for my Long-EZ build.

Dave
Flying LE VH-JZE and building
LE VH-XEZ


--
*********************************************************
David Berenholtz, Director
Southside Industries (Aust) Pty.Ltd.
P.O. Box 255 Black Rock Vic 3193 Australia

voice: + 61 3 9598 3000
email:   335dave@...
*********************************************************

Dave
 

re Baggage Pods

Further to Marc's reply, can any user of baggage pods give me a heads up on what changes they noticed with and without them in flight? Perhaps also full (heavy) vs empty. This may have me more prepared when testing.

Thanks!
Dave

Flying LE VH-JZE and building LE VH-XEZ


On Sat, Dec 7, 2019 at 12:43 PM Marc J. Zeitlin <marc.j.zeitlin@...> wrote:
Dave Berenholz wrote:

Does anyone have a test flying protocol for baggage pods to use during phase one testing?
I have the excellent Kevin Walsh document to adapt for my Long-EZ.

Assuming you follow Kevin's document, theoretically you'd need to repeat a substantial # of the tests both without and then with pods installed. These would include (but are probably not limited to) stall tests, climb tests, glide tests, stability tests, and flutter tests. Basically, anything that the aerodynamics and weight distribution of the pods might affect.

Most people don't do this when installing pods, of course, but most people seem not to do much in the way of testing in Phase I - they fly around in circles for 40 hours at a mid-CG, mid-weight condition and then call it good. Very disappointing. Be better than that.

--
Marc J. Zeitlin                      marc_zeitlin@...
                                            http://www.cozybuilders.org/
Copyright © 2019                     Burnside Aerospace



--
*********************************************************
David Berenholtz, Director
Southside Industries (Aust) Pty.Ltd.
P.O. Box 255 Black Rock Vic 3193 Australia

voice: + 61 3 9598 3000
email:   335dave@...
*********************************************************

Marc J. Zeitlin
 

Dave Berenhotlz wrote:

... can any user of baggage pods give me a heads up on what changes they noticed with and without them in flight? Perhaps also full (heavy) vs empty.

As you would expect, the pods add weight and drag, as well as some roll inertia. Not a lot of weight by themselves, and not a lot of weight even when loaded with the 25 lb. allowable in each. So maybe 75 lb. total, located about on the CG. You won't notice much of an effect from the weight.

But they certainly add drag. The EZ's and COZY's I've flown with and without pods seem to be about 7 KTAS slower at altitude (+/- 3 KTAS) with the pods on them, and climb a few hundred fpm slower than without pods. YMMV a bit.

If you can notice a roll response difference with the pods vs. without them, then you're a better test pilot than I am (not saying much, of course - I'm not a test pilot). While they are outboard of the strakes, so outboard of the fuel tanks, they only hold 25 lb (plus their own weight), so they're the equivalent of maybe 6 gallons of gas. Not a lot of extra inertia, but some.

There are a couple of folks that have claimed that the pods made them go faster by a few kts. This, of course, is complete nonsense, and speaks to a lack of accurate data gathering ability. There's no way that adding drag to a plane makes it faster, obviously. There were some interesting theories as to why their planes went faster with the pods :-).

--
Marc J. Zeitlin                      marc_zeitlin@...
                                            http://www.cozybuilders.org/
Copyright © 2019                     Burnside Aerospace

Keith Spreuer
 

Many claim they add roll stability by straightening the air flow. Possible but I'm skeptical 


On Sat, Dec 7, 2019, 3:47 PM Marc J. Zeitlin <marc.j.zeitlin@...> wrote:
Dave Berenhotlz wrote:

... can any user of baggage pods give me a heads up on what changes they noticed with and without them in flight? Perhaps also full (heavy) vs empty.

As you would expect, the pods add weight and drag, as well as some roll inertia. Not a lot of weight by themselves, and not a lot of weight even when loaded with the 25 lb. allowable in each. So maybe 75 lb. total, located about on the CG. You won't notice much of an effect from the weight.

But they certainly add drag. The EZ's and COZY's I've flown with and without pods seem to be about 7 KTAS slower at altitude (+/- 3 KTAS) with the pods on them, and climb a few hundred fpm slower than without pods. YMMV a bit.

If you can notice a roll response difference with the pods vs. without them, then you're a better test pilot than I am (not saying much, of course - I'm not a test pilot). While they are outboard of the strakes, so outboard of the fuel tanks, they only hold 25 lb (plus their own weight), so they're the equivalent of maybe 6 gallons of gas. Not a lot of extra inertia, but some.

There are a couple of folks that have claimed that the pods made them go faster by a few kts. This, of course, is complete nonsense, and speaks to a lack of accurate data gathering ability. There's no way that adding drag to a plane makes it faster, obviously. There were some interesting theories as to why their planes went faster with the pods :-).

--
Marc J. Zeitlin                      marc_zeitlin@...
                                            http://www.cozybuilders.org/
Copyright © 2019                     Burnside Aerospace

Marc J. Zeitlin
 

Keith Spreuer wrote:

Many claim they add roll stability by straightening the air flow. Possible but I'm skeptical

I don't even know what that means - roll stability... They're about on the CG, so even though they add area, they won't affect pitch or yaw (directional) stability much, if any.

But the spiral (roll stability) mode in these planes is generally negative and non-oscillatory, meaning that eventually, the plane will fall off to one side or the other and the roll angle will continue increasing if not corrected by the pilot. "Straightening the airflow" means nothing in this context.

So I'm with you - skeptical, at best.

--
Marc J. Zeitlin                      marc_zeitlin@...
                                            http://www.cozybuilders.org/
Copyright © 2019                     Burnside Aerospace