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rsrandazzo(at)precisionma
Guest

Posted: Sun May 28, 2006 10:53 pm Post subject: Any thoughts on FLAPS?

Commanders-



I'm still in the process of compiling me general fund of knowledge- and

thought you guys might be able to help with this mystery....



The Pilots Operating Handbook for the Commander 685 references conducting

all takeoffs with the flaps UP.



When I was checked out in N414C at purchase, the check pilot said that he

conducts all of his takeoffs at flaps 10.



I've used his advice- although for giggles I conducted one takeoff without

them just to feel the difference.



I found that performance (we are at 5200' MSL) was better with the flaps at

10, so this would seem to be my preference.



I have not scientifically conducted any takeoff distance/climb performance

measurements yet, obviously.



Anyone have any hard-fast logic on this?



Robert Randazzo

nico(at)cybersuperstore.c
Guest

Posted: Sun May 28, 2006 11:39 pm Post subject: Any thoughts on FLAPS?

I don't even take off a Cessna 150 without flaps set to at least 10.

Although the Commanders don't have Fowler flaps, it still increases lift

more than it increases drag at 10 deg. It just makes sense to increase lift

on take-off. When flap settings will cause the plane to lift off before VMC,

then I will take off without flaps, but Commanders will run off the end of

the world if the pilot doesn't positively rotate. Moreover, if an engine

fails immediately after take-off (who's paying attention to balanced

fields?), I kinda like the spread between stall speed and airspeed with 10

deg flaps. 

It's my 2c worth.

Nico

--

aquadiver99(at)yahoo.com
Guest

Posted: Mon May 29, 2006 8:18 am Post subject: Any thoughts on FLAPS?

Hey Robert, I own a 500B but the differences are VERY

little. My POH says the same. What I have found to be

the most beneficial is flaps up or 10, no great diff,

but as soon as you start rolling, maintain back

pressure on the yoke so at 85 mph or so you are

airborne. 

This technique reduces your ground roll and wear on

the nose wheel. Otherwise, you will remain on the

ground indefinitely until you finally pull back and

shoot up in the air.

--- "Robert S. Randazzo"

<rsrandazzo(at)precisionmanuals.com> wrote:



 	  Quote: 	
		   

 Randazzo" <rsrandazzo(at)precisionmanuals.com>

 

 Commanders-

 

 I'm still in the process of compiling me general

 fund of knowledge- and

 thought you guys might be able to help with this

 mystery....

 

 The Pilots Operating Handbook for the Commander 685

 references conducting

 all takeoffs with the flaps UP.

 

 When I was checked out in N414C at purchase, the

 check pilot said that he

 conducts all of his takeoffs at flaps 10.

 

 I've used his advice- although for giggles I

 conducted one takeoff without

 them just to feel the difference.

 

 I found that performance (we are at 5200' MSL) was

 better with the flaps at

 10, so this would seem to be my preference.

 

 I have not scientifically conducted any takeoff

 distance/climb performance

 measurements yet, obviously.

 

 Anyone have any hard-fast logic on this?

 

 Robert Randazzo

 

 

 

 



 browse

 Subscriptions page,

 FAQ,

 http://www.matronics.com/Navigator?Commander-List

 Admin.



 

 

 

  

  

  

 

 

 

 


	




Donnie Rose

205/492-8444



__________________________________________________

bowing74(at)earthlink.net
Guest

Posted: Mon May 29, 2006 8:44 am Post subject: Any thoughts on FLAPS?

I like "shooting up in the air".



bilbo



--

BillLeff1(at)aol.com
Guest

Posted: Mon May 29, 2006 10:45 am Post subject: Any thoughts on FLAPS?

That is true. The aircraft performs better as far as getting off the ground  

with 1/4 flaps but it degrades single engine performance. Just be careful and  

get those flaps up as soon as you get the gear up.

 

Bill Leff

CloudCraft(at)aol.com
Guest

Posted: Mon May 29, 2006 9:52 pm Post subject: Any thoughts on FLAPS?

In a message dated 28-May-06 23:54:44 Pacific Daylight Time, 

rsrandazzo(at)precisionmanuals.com writes:

I found that performance (we are at 5200' MSL) was better with the flaps at

10, so this would seem to be my preference.



I have not scientifically conducted any takeoff distance/climb performance

measurements yet, obviously.



Anyone have any hard-fast logic on this?

<><><><><><><><>

Robert,



In the words of Donald Rumsfeld, "There are things we know, there are things 

we don't know and there are things we don't know that we don't know."



I know a few things about Commanders, I know there are a few things I don't 

know about Commanders, and the rest is obvious.



I have never been able to figure out why the 685/690 airframes are zero flap 

take-off models. 



I found 10 degrees of flaps to be really effective on the 685; I operated 

mostly out of Lee's Summit in Missouri (KXLT) at 1000' on a 4010' runway.   I 

could see the end of it; it was too short.



Things I know: 10 degrees of Commander flaps are lift.  More than that is 

drag.  More than half flaps is a lot of drag.



Ted Smith airplanes (Commander, Aerostar, Jet Commander / Westwind) sit at a 

negative angle of attack on the ground.  For the science fans in the crowd, 

this was something I intuited and was confirmed by Ron Smith, Ted Smith's son. 



The negative angle of attack stance serves you on a short field landing but 

is something you have to overcome on take-off.



This explains the "leaping into the air" as Donnie has discovered.   If one 

accelerates without back pressure on the yoke a Commander will pearl dive and 

then with a hefty pull at your preferred Vr, you'll overcome the negative AOA 

and leap.



Try this: have a companion stand outside at the tail and yell to you when the 

elevator is streamlined.  Make note of where the yoke is.    Now hold the 

yoke there at the start of your next take-off roll.



As you accelerate, the amount of back pressure to hold a streamlined elevator 

will become less and you'll smoothly fly off.  (The bob weight for pitch feel 

will make you exercise a bit at each take-off; this counts towards your 

weekly gym time.)



If anyone out there knows -- or has anyone they can reach back to, who was 

involved with the 690 airframe design and certification who can enlighten me as 

to why this is a zero flap take off (per the AFM) please do let me know.   One 

theory I've heard is that the straight wing stub gave more lift than the 

continuous dihedral wings on other models and therefore flaps were not necessary.



My experience in the 685 does not bear this out.   On the Turbo Commanders, 

there's just so bloody much power and airflow over the inboard wing section 

that the take-off is a brief blur anyway and flaps would just be ... silly.



David Maytag, do you have any insight into this mystery?  You and your family 

have been around this model longer than a week.



Wing Commander Gordon



Life is not simple anywhere. Probably less so elsewhere.

BobsV35B(at)aol.com
Guest

Posted: Tue May 30, 2006 1:15 am Post subject: Any thoughts on FLAPS?

Good Morning Wing Commander Gordon,  



I absolutely DO NOT have any personal knowledge as to why the later Aero  

Commanders do not recommend flaps for takeoff, but I DO have a little  knowledge 

as to why the later Bonanzas do not recommend flaps for takeoff.

 

The FAA told Beech that if they were going to show any data for flapped  

takeoffs, they had to run tests under the observation of FAA inspectors to  verify 

the data in accordance with FAA specifications. The cost was high, but  even 

beyond that, the Beech Lawyers told management to back off and leave it  alone 

for liability reasons.

 

There is no prohibition against using flaps, but there is no official  

encouragement either.

 

I would not be at all surprised if Aero Commander encountered similar FAA  

and lawyer problems.  

 

One more comment. Ted Smith designed the airplane during the time when  the 

industry was beginning to take advantage of the minimum, or  negative, angle of 

attack on takeoff mode to aid acceleration on the  ground. 

 

If any of you are old enough to remember the Convair 240 as against the  

Convair 340, you may remember that the 340 sat on the ground with the nose a bit  

lower than did the 240. The idea was to reduce the drag during the 

acceleration  mode. It allowed for a slightly shorter accelerate stop number.

 

Just to add more data about which I know very little, back in the olden  days 

when I was flying Commanders a bit, I generally preferred the flapped  

takeoff, but I never did see any numbers developed that would have allowed me to  

estimate the effect it had on accelerate stop distance.

 

Happy  Skies,



Old Bob

AKA

Bob Siegfried

Ancient Aviator

Stearman  N3977A

Brookeridge Air Park LL22

Downers Grove, IL 60516

630  985-8503



 

In a message dated 5/30/2006 12:52:59 A.M. Central Standard Time,  

CloudCraft(at)aol.com writes:



If  anyone out there knows -- or has anyone they can reach back to, who was  

involved with the 690 airframe design and certification who can enlighten  me 

as 

to why this is a zero flap take off (per the AFM) please do let me  know.   

One 

theory I've heard is that the straight wing stub  gave more lift than the 

continuous dihedral wings on other models and  therefore flaps were not 

necessary.

rsrandazzo(at)precisionma
Guest

Posted: Tue May 30, 2006 11:05 am Post subject: Any thoughts on FLAPS?

Bob-



Following this observation:



*** 

Just to add more data about which I know very little, back in the olden

days when I was flying Commanders a bit, I generally preferred the flapped

takeoff, but I never did see any numbers developed that would have allowed

me to estimate the effect it had on accelerate stop distance.

***



I noticed that the airplane leaves the runway more affirmatively at Flaps10

than Flaps0.  At Flaps0, the airplane seemed to wallow for a moment when

leaving ground effect.  I didn't get the same impression at Flaps10....



Once N414C is flying again- I'll take some notes and see how performance

differs.  Even though we don't have any specific information it might make

for some good knowledge all the same.



Robert Randazzo

rsrandazzo(at)precisionma
Guest

Posted: Tue May 30, 2006 11:10 am Post subject: Any thoughts on FLAPS?

WCG-



Interesting notes on the neutral position.  Filed away for future use.  I'll

post my feedback at that time.



Robert Randazzo



Do not archive



 



--

nico(at)cybersuperstore.c
Guest

Posted: Tue May 30, 2006 12:00 pm Post subject: Any thoughts on FLAPS?

With Flaps 0, one would have a steeper deck angle; the rotation would then

be through more degrees. A steeper deck angle is also a scary part for me so

close to the ground at minimums. (minima)

--

STOLHorse(at)aol.com
Guest

Posted: Tue May 30, 2006 4:05 pm Post subject: Any thoughts on FLAPS?

This is one of those questions I've wondered about for a long time, too.  

Here's my thoughts on the subject:



I think Old Bob is on the right track and they maybe just didn't test it 

because, as Keith said, the 690's have so much power that it just didn't make 

enough difference to justify the time and expense of the testing and approval of 

the data.  As airplanes evolve, the manufacturers are all guilty of "evolving" 

the data and procedures along with it from previous models.  Usually, this is 

no big deal but you can find examples of it everywhere, even on certain TC 

Data sheets.  Perhaps this is the case with the 685 too.  Since it came after the 

690, maybe the culture was to change as little as possible and the flaps-up 

take off just came along.  I don't know.  Giving the engineers the benefit of 

the doubt, though, I just figured it had something to do with meeting single 

engine climb requirements so I take off with the flaps up in the 685.



The technique I've been using to coax the 685 off the ground has been working 

well for me and I fly it at or very near gross weight and I go to high 

altitude airports.  I will not take it to Aspen or Telluride, however.  The places I 

go do have pretty good options should the airplane decide it just can't do it 

on one engine.  I always seem to come up with about 120 to 200 fpm climb on 

one engine when I check the performance numbers.  I just don't have a whole lot 

of confidence in those numbers in the real world with a scared-$%^*less me at 

the controls vs. the highly skilled and expecting it test pilot.



I take off with full power and I take my time getting the engines to full 

power so I don't thermally shock them or cause the turbo to surge.  If it's busy, 

I'll even ask for a momentary delay on takeoff so the controllers will know 

I'm not going to blast out of there like a 690.  At brake release, I have my 8 

year old son close the cowl flaps for me while I go in the back to get my 

lunch.  (In my opinion, the cowl flaps affect takeoff performance much more than 

the difference in flap settings.)  After I get back to the front seat with my 

sandwich, I see that we are approaching Vr.  I like to leave the 685 on the 

ground about 8 to 10 knots above the book Vr of 92 kias.  I rotate at about 95 

and lift off about 100 or even a bit above that.  It's about the same as the 

690's.  My theory here is that speed is my best friend right now because it seems 

to take forever to get from liftoff to 111kias Vyse.  I don't want to pull it 

off way down around 90 (the short field technique calls for 83 indicated - 

yikes!) and double the speed that I need to gain to get to the best SE climb.  I 

don't go to short runways so that is not a factor in this technique.  Also, 

liftoff at 100 knots is very gentle and positive.  That's one of my favorite 

things about Commanders:  If you set the trim right, you can make the most 

effortless and smoothest transition from ground to air that I have experienced in 

any plane - something King Airs can only dream about.  While the airplane 

accelerates, I watch the engine temps and adjust the cowlflaps accordingly.  

Usually in the winter they just stay closed but in summer, especially out of Bermuda 

Dunes, I need to open them halfway or so.  You can see the temps rising on 

takeoff but as soon as you open the cowl flaps just a little they will stop 

rising almost immediately and I've never seen them go above 400 degrees even in 

the heat.  There's just a ton of cooling drag on this plane and with the cowl 

flaps open you get 4 nifty little spoilers working against  you too.



Anyway, if you're still reading, that's my two cents worth.  Bottom line is 

that I pick my airports very careful with this plane but I have found that the 

685 has exceeded my expectations by a large margin.  I think most of the 

badmouthing of the airplane is unfounded and a result of comparing it to the 690's. 

 Let's compare it to a 421 or P-Navajo.  Oh yeah, there's no comparison.



David Maytag

bowing74(at)earthlink.net
Guest

Posted: Tue May 30, 2006 4:26 pm Post subject: Any thoughts on FLAPS?

I had heard a friend talk about the effect of the cowl flaps on the

Commander and never thought much about it until I was trying to figure out

why my 500A wouldn't "Go".  It wouldn't climb, hardly at all, and the speed

at level off was just not there.  Invariably I would look back and see the

cowl flaps open.



I found 2 things.  

1 if I could see them the performance was going to be dramatically effected.



2 on the 500A it doesn't matter whether they are open of closed.  The temps

are always cold.  So I will leave them closed.  



If I ever get it flying again.



bilbo



--

rsrandazzo(at)precisionma
Guest

Posted: Tue May 30, 2006 4:28 pm Post subject: Any thoughts on FLAPS?

David-



Thanks for the info!  Apsen/Telluride....  I've flown Part 121 airplanes

loaded with passengers in/out of those places and didn't feel comfortable

with my options.  I'd never conceive of taking the 685 there.



The beauty of tossing a set of Chelton's into this airplane is that the

Flight Path Vector becomes a very handy tool when navigating rising terrain

with a climb performance problem.



You mind sharing a bit of your experience on runway length and your

"selection process?"  (You mentioned that you pick your airports

carefully... Thought I might gain from your experience...)



I operate out of a field with 7000 and 9500' of runway- which provides me

with plenty of opportunities.  Generally speaking I'm headed to places with

11000+ in runway length- but I imagine that as I get more comfortable with

the bird I'll be using it into some smaller spaces as well.



I like to take my time getting used to new airplanes....



You get your props worked out, David?  Both props on N414C overhauled with

no problems- but I had my fingers crossed after hearing about yours...



Robert Randazzo



 



--

john(at)vormbaum.com
Guest

Posted: Tue May 30, 2006 5:56 pm Post subject: Any thoughts on FLAPS?

David,



Bermuda Dunes!!!!!



On a balmy 105-degree Palm Desert day, that runway seems awful short to me. 

You're a brave man to be flying a 685 out of there.



/John



Do Not Archive



---

STOLHorse(at)aol.com
Guest

Posted: Tue May 30, 2006 6:43 pm Post subject: Any thoughts on FLAPS?

Yep, the Chelton system is awesome.  I think it's the best system you can buy 

right now.  



I don't have any kind of scientific way I pick airports I just meant that I 

look at the surroundings and temperatures more than just runway length.  

Aspen's runway is long enough but the valley gets pretty narrow and highway 82 is 

dangerous enough without 9000 pound puddle jumpers skimming the rooftops of 

SUV's at 150 miles an hour.  I like to see a lot of open space and flat or 

lowering terrain.  I've noticed that the airplane will climb pretty well once it 

reaches 120 or so which is why I like to get it to that speed or more as fast as I 

can.  At full power and gross weight, I see about 1200- 1300 fpm at gross 

weight coming off of a 5000' elevation airport.  I just don't like to leave them 

at full power any longer than necessary (even though Continental says you can 

all day long) and at max recommended climb power I see around 700 fpm so 

mountain valleys are something I avoid.  I'm also much more cautious about weather 

in this plane.  I don't do low ceilings (as in less than a few thousand feet) 

or any moist winter cold fronts where the possibility of ice is obvious.



I did finally get a pair of sharp looking overhauled propellers just last 

Friday.  It was a challenge but with my spare prop and some careful searching by 

the good folks at Nevada Propeller/Executive Propeller, we finally came up 

with 6 real good blades and one hub.  I was really worried though at first 

because the initial reaction from all the prop shops was one of complete futility.  

You know like "Oh, I haven't seen one of those props in 30 years"  or "What 

model of prop did you say that was?"  or "What model of Commander did you say 

those go on?"

STOLHorse(at)aol.com
Guest

Posted: Tue May 30, 2006 8:28 pm Post subject: Any thoughts on FLAPS?

John,

 

You've exposed my hypocrisy already!

 

Actually, Bermuda Dunes is the shortest runway I've gone to but the  airplane 

does just fine.  I don't fly out of there heavy in the middle of  the 

afternoon, though.   I always plan the heavy departures for early  morning but I have 

left there lightly loaded in 105 degrees.  It's still  not as scary as flying 

heavy 747-100's out of Ramstein on a hot afternoon!

 

I'm sure most of you can appreciate the load hauling capability of  

Commanders, But I have to tell you what my "normal load" is when I go to Bermuda  Dunes:

 

Two dogs,

Two cats,

Two women,

Two kids,

and Me.  

Plus enough fuel to go 650 miles with reserves.  Oh yeah, and I'm not  

talking about two lap dogs -- one is a Labrador and the other is a Great  Dane.  

Luckily, they are good buddies.

 

I need help.

 

David Maytag

CloudCraft(at)aol.com
Guest

Posted: Tue May 30, 2006 8:33 pm Post subject: Any thoughts on FLAPS?

In a message dated 30-May-06 21:28:51 Pacific Daylight Time, 

STOLHorse(at)aol.com writes:

Two dogs,

Two cats,

Two women,

Two kids,

and Me.  

 ...

I need help.



Help?  Sounds like you need a HAZMAT program!



By the way, thanks for bringing up the matter of cowl flaps.  That's an 

important piece of the take-off puzzle.



Wing Commander Gordon



Life is not simple anywhere. Probably less so elsewhere.

tfisher(at)commandergroup
Guest

Posted: Tue May 30, 2006 10:35 pm Post subject: Any thoughts on FLAPS?

My German Short Haired Pointer (75 Lbs.) has the bench seat to himself.

I operate at gross weight all the time from 3500' sea level runways.

I lighten my nose wheel at 80 mph and rotate at 105 mph with 10 deg. flaps.

Tom F.

C-GISS 680 FLP (Mr.RPM)



---

barry.collman(at)air-brit
Guest

Posted: Wed May 31, 2006 2:31 am Post subject: Any thoughts on FLAPS?

Hi All,



I've flown with an Iguana. Beat that!!!!!



Barry C.



---

rcdettmer(at)charter.net
Guest

Posted: Wed May 31, 2006 5:42 am Post subject: Any thoughts on FLAPS?

I have been enjoying the discussion about flap settings on take-off, and

short vs long runways at high and hot airports.  Just want to share my

experiences in my 680F.  I have routinely been using 10 degrees of flaps for

takeoff, with rotation at 80 kts, initial climb at 100 kts, and cruise climb

(after about 800 feet asl) at 140 kts and 1000 fpm.  Doesn't seem to change

whether light or at gross weight (8,000 lbs)...always the same 140 kts and

1,000 fpm.  If the air temp isn't too hot, I will take off with cowl flaps

in trail (about half open)...desn't seem to affect climb performance, but

would probably make a difference on one engine.  I remember coming out of

Carson City and Las Vegas at near gross weight (7 persons and lots of

baggage) in summer with air temps well above 90...airplane jumped off the

runway and performed as if it was wintertime.  Of course, those runways have

plenty of length and flat land around if one engine quits.



Thanks for the good discussions



Randy Dettmer, AIA

680F / N6253X



DettmerArchitecture

805 541 4864 / Fax 805 541 4865

www.dettmerarchitecture.com



--

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