Super Dave

After page 4 I decided to rent a power dead horse beater; at this point, it would've been cheaper to just buy.

As I tried to explain somewhere back along this long and winding road - 'taint true. A wing with flaps extended (extended a little, or extended a lot) will always create a higher coefficient of total drag for a given coefficient of lift when compared to a flaps up wing.

Sorry, I was sloppy with my notation, I should have written it as (L/D)max, or maximum lift to drag ratio. I was using (L/D)max to reflect the effect of flaps on the entire lift to drag curve. Flaps will only add a very small amount of parasite drag on the takeoff roll. It's not until liftoff or near liftoff that the production of lift and induced drag have any significant impact on total drag. The small amount of additional drag up to that point is far outweighed by the lower speed required to liftoff.

First, the question of time to altitude, or climb rate: As you described, plane 2 will take a couple more seconds to reach flying speed, but once it does, it is immediately gaining on airplane 1 in height. This is nothing but a guess on my part, but I'd wager that airplane 2 reaches 50' before airplane 1. I am certain however, that airplane 2 will be higher than airplane 1 by the time airplane 1 dumps flaps and accelerates to Vy. Any advantage that was gained in the takeoff roll will have to be payed back at flap retraction, in addition to the penalty of carrying those flaps to 51'. Extended flaps will always increase the coefficient of drag proportionately more than the coefficient of lift. Secondly, the question of climb angle: If airplane 2 accelerates to Vy after takeoff, it's path will never intersect with the path of airplane 1. And yes, if airplane 1 just squeaks over the 50' obstacle, airplane two will not survive the experiment.

Yes, L/Dmax will always go down with the extension of flaps. L/Dmax will also occur at a lower airspeed with the extension of flaps. The aircraft lifts off sooner with takeoff flaps because the flaps increase the coefficient of lift. This means that the wing can produce the required lift at a lower speed than would be required with no flaps. Since the airplane needs less speed to lift off, it can accelerate to that lower speed in less distance. Once airborne, the airplane will not climb as well (in rate or gradient), but if we are concerned about a short runway or a 50' tree at the end of a short runway, we want takeoff flaps because the decrease in takeoff roll outweighs the penalty we pay in climb. If the obstacle were high enough and far enough away (we don't know how high or far because Mooney didn't supply the data) it would be better to leave flaps up because the improved climb performance will outweigh the longer takeoff roll. We could shorten our takeoff roll even further by using full flaps (I'm not suggesting anyone actually tries this); The airplane would not climb very well at all once airborne, but you could easily beat book numbers on the takeoff roll. There is nothing magical or particularly efficient about takeoff flaps. Takeoff flap setting was determined to be the "right" amount of flap by company test pilots because that particular setting resulted in the least distance required to clear the industry standard 50' obstacle while still allowing acceptable climb performance. If the industry standard was a 25' obstacle, we would all be setting more flaps for takeoff, if the industry standard was a 100' obstacle, we would all be setting less flaps at takeoff. As for designing a flap that increases coefficient of lift while also increasing L/Dmax, you may as well set out to invent a perpetual motion machine.

I'd like to stop beating on poor old Trigger, but performance and aerodynamics are subjects near and dear to my heart and I can't bring myself to walk away. It's not an assumption of mine that planes climb faster without flaps, it's an irrefutable law of aerodynamics. Climb performance is determined strictly by excess power or excess thrust. In propeller aircraft, best rate of climb (Vy) occurs at the speed which yields the greatest margin between power required and power available. In jet and propeller aircraft, the best angle of climb (Vx) occurs at the speed which yields the greatest margin between thrust required and thrust available. Extending flaps to any degree increases the coefficient of lift. This means that a wing with flaps extended can produce the same amount of lift at a lower speed than the clean wing does. This reduces stall speed and allows us to takeoff or land at a slower airspeed, making for shorter takeoff or landing rolls. Unfortunately there is no free lunch because flaps also increase the coefficient of total drag. Total drag is the sum of the coefficient of drag at zero lift (a measure of parasite drag), and the coefficient of induced drag. This is where the penalty lies - the coefficient of induced drag is proportional to the SQUARE of the coefficient of lift. Despite your flight instructor telling you that such and such a flap angle "increases lift more than drag" (my first flight instructor told me the same thing), extending flaps to any degree will always increase the coefficient of drag proportionately more than the coefficient of lift. One other note; because extending flaps increases the coefficients of lift and drag, the airspeeds at which maximin excess thrust and power occur will be reduced. The POHs for some aircraft will list Vy or Vx for various configurations, and the airspeed values will always be somewhat lower with flaps or gear extended. As will be the rate or angle of climb. As for the POH of your '68C, I was puzzled, but I found a complete POH for a '66 C on Delta's website and it has the same information (although in a graph instead of a table) specifying "gear up-flaps15"on the graph. However, just above the graph it says "CLIMB CONFIGURATION: Gear Up - Best Power Mixture - Cowl Flaps Open - Flaps Up". Mooney built great airplanes, but Cessna, Piper and Beech were way ahead on POHs.

"Fate is the Hunter" by Earnest K. Gann "A Gift of Wings" by Richard Bach

It certainly does to the CHTs

Good idea, I'll try it next time I'm horsing around the pattern. I'm not an absolutist either; my goal in making these silly arguments is just to give the takeoff flap absolutists something to think about. I enjoy the debate, and maybe I'll learn something that will change my ways. Just to be clear, I'll restate that I do not hesitate to use takeoff flaps when runway length or close in obstacles are a concern. I round the book numbers up and then double them. Even so, I find myself rarely using flaps.

I respectfully disagree with your analysis. The engine does not care how far down the runway it is when it decides to fail, it is going to fail at a given point in TIME after power application. It may give you a sense of satisfaction to look at down at the departure end of the runway from 800-1000' after climbing out at 90mph with flaps, but in that instant, if you could look out your windscreen and see an identical airplane that had started its takeoff simultaneously with you, but had instead taken off with no flaps and climbed out at Vy, you would see an airplane that is farther down range, higher in altitude, and with more airspeed to play with in a glide. If both of your engines quit or blew a jug at this instant, which airplane would you rather be in? The kicker is that the imaginary airplanes CHTs are also cooler than yours as a result of the higher airspeed, so maybe his engine will last another minute and he'll be at 2000' when it develops a problem. Even better, if the imaginary airplane had been operated this way over the life of the engine, maybe it'll go another 100 hours before failure.

Shorter ground run-yes, lower liftoff speed-yes, shorter distance to clear obstacles-sometimes. If the obstacle is 50'-yes, if the obstacle is 1000'-no. Where is the break even point? I don't know, but I would guess that it is closer to 50' than 1000'. Assuming that runway length or obstacle clearence is not a factor, I do count a few marginal advantages to no flap takeoffs. For example, I happily sacrifice some additional wear and tear on the tires/gear to realize better airspeed for engine cooling earlier in the climbout. I realize it's splitting hairs, but I'd rather split my hairs to favor CHTs over tires.

1. I did not mean to suggest that we should all be doing no flap takeoffs because Bob Kromer says so. I was just making a counter point to all of the responses that stated with absolute certainty that configuring with takeoff flaps is the only proper way to fly a Mooney, and that anyone who suggests otherwise is clueless. Some were citing factory test pilots and POHs, and I thought using Kromer as an example of the no flap camp was ironic because he was a factory test pilot that had a hand in developing POHs. 2. Actually, my analysis takes total drag into account. You can try it out yourself by running a few climb tests. Establish a stabilized Vy climb at something like 500' AGL, give yourself another 500' to stabilize and start a timer passing through 1000', stop the timer passing through 3000'. Next, take another run from the same altitudes using takeoff flaps and compare the results. If CHTs are a concern, the test could be run at some arbitrary amount higher than Vy, but this will exaggerate the no flap advantage.

I would disregard the comments bashing your instructor, after all, Bob Kromer recommends no flap takeoffs and he was a Mooney factory engineering test pilot. As for the POH recommendation, I don't know about your E, but my 76F POH says to set flaps at "TAKEOFF OR AS DESIRED". Even if your POH only recommends takeoff flaps, it is just a recommendation unless it is in the limitations section. My routine is to check the distance required to clear a 50' obstacle from my POH, and then I double that number. If the result is anything close the the runway available, I use takeoff flaps. If not, I prefer flaps up because once airborne, the airplane accelerates more quickly and climbs at a better rate and gradient with flaps up. Many pilots have the sense that climb performance is somehow improved by flaps, but this is incorrect. Climb performance is determined by excess power or thrust, not excess lift. Since flaps increase drag, they reduce excess power and degrade climb performance. If flaps improved climb performance, we would use them all the way to cruising altitude. On the other hand, flaps can help us clear an obstacle at the end of a short runway. By getting airborne in less distance, flaps help us start our climb further from the obstacle, and that obstacle can be cleared with greater margin, even with the degraded climb performance. My advice is to become comfortable with both configurations and use either depending on the situation.

Oshkosh, WI (KOSH) has a Hilton Garden Inn that you can literally taxi right up to. One of the FBOs will deliver fuel to the hotel ramp. Bar and restaurant in the Hotel, and a couple more places within a short walk. The EAA museum is also on the field, which could occupy two days if you take your time.

I use Foreflight enroute and for weather, but I'm a big fan of flightplan.com for planning and fileing. After setting up a performance profile for your aircraft, flightplan.com makes it easy to compare incredibly accurate times and fuel burns at various altitudes.

Climbing at an airspeed lower than Vy is only hurting your climb rate. The definition of Vy is the BEST RATE of CLIMB airspeed. Pitching up to a lower airspeed may appear to increase climb rate, but this is only temporary. Once the airplane settles down at it's new lower airspeed, climb rate will be lower than if it had been left at Vy all along. Next time you go flying, try maintaining an airspeed no lower than Vy all the way up to 8000' and I think you will find your climb rate is significantly better than 300FPM.

I think you need to increase your IAS. Vy for my F is ~91KIAS at those altitudes. I would guess that Vy in a J might be even higher. In any case, once obstacles are cleared I would consider Vy a minimum climb speed, and instead usually settle at around 105KIAS for better cooling, visibility, and forward speed while sacrificing little in climb rate.

Oh, I didn't realize Fltplan had a NEW app.

I have used Fltplan's app for the free charts and plates and found them to work fairly well. I would recommend it to someone who mostly flies locally for fun and rarely does longer cross countries. Having said that, if you are willing to spring for the $75 Foreflight subscription, it's easier, slicker, prettier, and has a lot of useful features that Fltplan lacks.

Any updates on technique/strategy? I'm planing on entering my 76F in the Northwoods 100 next weekend. Specifically, I'm wondering about start and finish strategy considering this race has a flying start/finish at the departure airport. The finish seems pretty straight forward; I'll attempt to cross the finish line at minimal allowable altitude at the bottom of a gentle dive. But I'm not sure how to handle the start. As I understand it, we takeoff, climb to altitude while circling the airport, and cross the start line on a parallel taxiway. So, should I climb to the max allowable altitude while circling and then dive to the minimum allowable altitude as I cross the start. Or should I hold on to that potential energy and cross the start line at or above the altitude that I plan to fly my first leg at? It seems to me that crossing the start line at the bottom of a high speed dive is a wasting energy on a lot of extra parasitic drag, and that it would be better to slowly play out the extra altitude on the first leg, but I'm only guessing. What do you see the experienced racers doing?

Even though you do not need a clearance to operate IFR in class G, you still need to follow all other IFR rules... terrain clearance, cruising altitudes, flight visibility landing minimums, etc. In parts of the US that class G only extends up to 700' AGL, the FAA has issued violations for operating IFR in class G without a clearance, under "careless and reckless". In parts of the country (like some parts of Alaska) where class G extends all the way to 14,500' it is possible to take off, cruise, land under IFR without a flight plan, clearance, or communication with ATC. However, most working airplanes cannot operate IFR in uncontrolled airspace because it is prohibited by their part 121/125/135 op-specs.

I don't know your model or engine. But for my IO360A1A, I actually need to tweak the mixture back a little in the descent to keep FF constant. If your FF naturally remains constant or decreases in the descent, I would leave it alone, unless I needed to enrichen for smoothness or more power.

I keep it LOP all the way in. As fuel flow creeps up in the descent, I adjust mixture to keep fuel flow at the same value. This results in a constant HP as the engine goes farther and farther LOP as MP increases in the descent. At some point, throttle is reduced, and I leave the mixture alone till tweaking it for the taxi to the hanger. I've also experimented with maintaining a constant EGT in the descent, which works fine, but this increases HP as you descend and it may be possible to move into the "red box" as you descend. Maintaining a constant fuel flow keeps a constant HP and you actually move farther away from the red box as you go farther LOP. I have a throttle quadrant, so I remind myself that in the event of a go-around I'll need to push a handful of levers forward. If I had vernier controls I might consider going full rich at the final GUMP check. My IO360 with stock injecters stays smooth using this method. But if yours starts to run rough as it goes farther LOP, you could enrichen just enough to keep things smooth.

A small radius leading edge will acumulate ice at a greater rate than a leading edge with a larger radius. Tails build ice faster than wings, props build ice faster than tails.

Funny, I'm sitting at Newark Liberty as I write this, and I completely agree. Even though ground was helpfull and our taxi route was pretty straight forward, taxing to Signature after landing was by far the most stressful part of my morning. Geo referenced airport diagrams are great, but personally, I wouldn't fly into the primary airport of a class B without another qualified pilot to navigate and copy taxi instructions.