Cowl-flap as speed brake?

Hi,

Has anyone seen examples of an over-sized, over-extendable, cowl flap that also doubles as a speed brake?

As I was driving into work yesterday, it occurred to me that an oversized cowl-flap might work as a speed brake. Hinged at the front, the rear could have a linkage so it could be pushed down, normal to the direction of flight, to increase drag and steepen the approach. I was remembering a belly-board, speed brake seen on a Velocity. I tried a Google search but no hits, yet.

Speculation on my part, an over-extended, cowl flap might add some up-pitch to the plane. My thinking is to contact the owner(s) to see if they have any pilot reports on other flight characteristic and lessons learned about the cabin control and latching mechanism.

Thanks,
Bob Wilson

I know that the cowl flaps on the Corsair (F4U) were a source of drag on the aircraft.

I'd be concerned about the pitch up, especially if it was used during landing in a tailwheel.

Why, if you need speedbrakes/spoilers, not just put them on top of the wing? That way when you can use them as both a way to slow down and after touchdown to maximize braking effectiveness by disrupting lift by spoiling the airflow.

The only drawback is getting them sized correctly for use during flight so that you don't kill too much of your lift.....

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Originally Posted by bwilson4web

Hi,Has anyone seen examples of an over-sized, over-extendable, cowl flap that also doubles as a speed brake?As I was driving into work yesterday, it occurred to me that an oversized cowl-flap might work as a speed brake.

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Wouldn't you be compromising the primary function of controlling engine temps?

Cowl flaps have to be located and sized to manage engine temps. Speed brakes create both flat plate drag and often also destroy wing lift. The two engineering requirements really do not overlap in practice except in odd cases.

I own a set of Precise Flight speed brakes and know of some other types of speed brakes. Putting them on top of the wing provides the maximum effectiveness as they destroy wing lift and create a little more drag due to the slightly higher air velocity in that location. Putting them on the fuselage of a prop plane is less efficient as the air is already disturbed by the prop. Translated that means they must be larger and heavier. And they have to be located aft for stability and other practical reasons which starts to get into CG issues.

Wing mounted brakes must be sized so that if they malfunction and only one deploys the airplane is still controllable.

I will note that wing mounted speed boards have to be located to avoid creating aileron flutter.

Most pilots get no real utility from speed brakes. Unless you are hauling skydivers, you don't need to come downhill that fast. Pops the passengers ears and makes them ill. Better to use the 1 mile for every 1000' of descent rule and plan to start down earlier. And if your speed brakes are not a manual linkage (heavier) you generally do not want to deploy them to slow down as you cross the numbers. They generally do not deploy exactly synchronized so you will have the airplane wiggle a little just as you are flaring. Tried all that.

If you want to know what it is like to come down at 4000'+ per minute, go buy a right seat ride at the local skydiving center.

The better speed brake is a constant speed prop and full RPM. Another plus on the list of reasons to use a constant speed prop.

Best of luck,

Wes
N78PS

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Originally Posted by WLIU

. . .
The better speed brake is a constant speed prop and full RPM. Another plus on the list of reasons to use a constant speed prop.
. . .

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I am going with an inflight-adjustable prop with a constant speed controller. I hadn't considered this and it makes a lot of sense.

If flight testing shows a speed brake is needed, it will easy enough to solve it then. No need to sign-up for something that may not be needed.

Thanks,
Bob Wilson

you could always try well planned descents...

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If you want to know what it is like to come down at 4000'+ per minute, go buy a right seat ride at the local skydiving center.

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Yeah, the idea of doing a spoiler deployed, power off descent on the way home from a $100 hamburger run. There's a reason why the military cargo guys joke you can tell whether a tactical approach was left hand or right hand based on which side of the compartment the vomit is most prevalent on.

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The better speed brake is a constant speed prop and full RPM. Another plus on the list of reasons to use a constant speed prop.

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Assuming you don't mind pissing off the airport neighbors and listening to the NIMBY jerks.....much better to just deploy the "rubber spoilers" landing gear) and increase your rate of descent and slow down that way.

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And if your speed brakes are not a manual linkage (heavier) you generally do not want to deploy them to slow down as you cross the numbers. They generally do not deploy exactly synchronized so you will have the airplane wiggle a little just as you are flaring. Tried all that.

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We're working on a system for our primary design that deploys when the weight goes on the wheels based on the squat switch activating.

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you could always try well planned descents...

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This is true. My intent is for the spoilers to only be used in flight if we need to make an exceptionally rapid descent (for example, loss of cabin pressure, etc). They also come in handy when ATC completely changes what you had in mind (Example: "If you can get down quick, we can squeeze you in with a direct vector for final".....being nice to the ATCers and getting to know them has its advantages).

Bob: I like the out of the box thinking; combining functions is always a good thing. But, the problem with cowl flap speed brakes is that when you most want them open (takeoff/climb) you don't want the added drag, and when you want the drag (coming down) you want the engine cowled to keep it warm. I also like Tony's comment: Plan ahead.

Nobody has mentioned slipping the airplane either. Oh, that's right, we don't teach using your feet anymore (tic).

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Originally Posted by bwilson4web

I was remembering a belly-board, speed brake seen on a Velocity.

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As Wes mentions, on a tractor prop, there's disturbed flow to worry about. That's probably a good reason these are more commonly seen on pusher configs. Also, canard-configured aircraft (generally) don't have flaps, so the need for something to increase drag may drive more designers/builders/operators of those types to want to add the additional hardware. Bob - I'm not sure what you are working on, I'm just saying that there's reasons you saw a control surface on a canard-configured airplane that don't translate to "more traditional" configurations.

This might help explain what I was thinking about:
http://www.cfiamerica.com/images/7725-cowl-flap.JPG
IF I decide I need a speed brake, my cowl flap will be a little longer and extend beyond 60 degrees.

The whole idea is to increase drag so the plane will descend at a steeper angle. But this is not something I have to do in the first version other than to make sure the linkage supports a larger extension. If the plane needs more drag, a longer replacement and/or a perforated plate (aka., SDB dive bomber) will work.

Bob Wilson

Bob, seriously....one has to be very careful with putting speed brakes, etc on aircraft because if you get it wrong you're not going to live long enough to sort it out. A strong enough pitch down (such as might occur in a mis-sized or over-extended speed brake) and you could be rendered unconscious or severely incapacitated as it doesn't take that much negative G to red someone out.


There's a very good reason this sort of thing on commercially built aircraft is extensively wind tunnel tested before they ever try it in flight. I have a hard copy of the wind tunnel test reports for the SBD's dive brakes (you'd be amazed the crap you stumble across from time to time). It's in excess of 100 pages long and is more boring than a French novel....just on the dive brakes. I say this as someone who does not want to hear of another friend (and as pilots, we're all brothers and sisters or at least friends regardless of whether always see eye-to-eye or have ever met) getting hurt or killed.

If you need to get down quickly (such as an ATC request), either use my favorite phrase ("unable") or request a 360 descent to give yourself more "room". A lot of pilots for some reason seem to forget that there's nothing wrong with making a 360 for separation or descent. The idea of "direct to" seems to override even basic piloting skills or non-linear thinking as a problem solving technique in this day and age of GPS and the magenta line of doom. Since we're not trying to avoid enemy fire while putting a bomb onto a Jap flat-top, I can't see any need for a "dive brake" on a light piston engine aircraft. I really don't mean this the way it's going to sound but there's really no polite way to put this: It's far better to learn how to properly fly the airplane as it was design than it is to go seeking engineering solutions to what is most likely a human factors problem. That's not to mention that it's a lot more fun because you get to fly while doing it. :)

Here is the interaction between cowl flaps and speed brakes on an airplane that has both - When you want to descend fast you close the cowl flaps to keep the engine from overcooling and you extend the speed brakes to increase your drag. If you have ever seen and engine stop from being too cold (think winter extended glides at idle power) then you will want to keep your engine temps well into the green arcs on descents.

The two controls are used almost always oppositely at the same time.

Best of luck,

Wes

Hi,

This is the aircraft, a Viking Dragonfly:
http://hiwaay.net/~bzwilson/dragonfly/2012/DF2.jpg
The center of gravity is ~58" from the prop or roughly between the seat-back and instrument panel.

The new engine configuration:
http://hiwaay.net/~bzwilson/dragonfl...rewall_140.jpg

So the proposed cowl flap / speed brake will hinge just behind the radiator. In normal flight, it will be parallel to the air stream. In climb, slightly down to increase radiator cooling at climb speed, ~80-90 mph.

When over-extended down, there will be two forces:

• drag - significantly increased, it will have a moment arm of about 14"
• radiator drag - maximum airflow will further add to the drag with a shorter moment arm, ~7"
• lift - only from any static pressure increase, it has moment arm of about 35-40" and opposite to the drag force

Without flight measurements, it is too soon to know how these forces will balance but having opposite signs, there is a chance they may be trim neutral. Flight testing and careful metrics will find out.

I'm going with a water cooled engine with a thermostat. During engine warm-up and descents, the thermostat closes to preserve engine block heat. Even with the cowl flap / speed brake maximum open and maximum cooling air through the radiator, the thermostat controls how much, if any, goes to the engine block.

I learned to fly at Hyde Field that has power lines to the North and trees to the South. The nearest airport with hangars is Hartselle AL with trees to the South and the town to the North. Emergency landing fields are often worse with fences, trees, power lines, and all sorts of unexpected things to fly into on the way down. The cowl flap / speed brake provides another mechanism to steepen the approach in addition to a slip.

The operational scenario is:

• downwind - 80 mph, clear traffic, cowl to climb position.
• crosswind - 75 mph, clear traffic, monitor obstacles and keep well above
• final - cowl flap / speed brake to maximum, add power, trim 65-70 mph, clear obstacles
• approach to flair - adjust power to reach numbers at 65 mph
• wheels landing - pull power . . . brakes . . . turn-off . . . close cowl flaps

They are a safety feature to give additional, approach angle control to augment a slip if needed.

Bob Wilson

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The cowl flap / speed brake provides another mechanism to steepen the approach in addition to a slip.

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They are a safety feature to give additional, approach angle control to augment a slip if needed.

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Assuming you do it correctly, otherwise it turns what should be an orderly glide to approach into a plummeting spine-splintering slam to the ground. That's assuming you don't pitch the nose over and end up with your engine in your lap.

I'm getting you are set on doing this and I've said all I can as to why there is a better than even chance that it will work out as nicely as you think it will.. If you don't mind my asking, can you PM me your address as I have a release form I would like you to sign before you pursue this any further.

Now that I've seen the plane, I'm wondering why you'd worry about a speed brake for descents - that thing looks ready to slip like nobody's business!

Bring the throttle back, crank it sideways and follow the elevator down!

Today's "high-performance" airplanes are like old fashioned muscle cars... old fashioned airframes (1930's technology) with big engines. They are typically very draggy and don't need speed brakes for approach control or landing. Small speed brakes are sometimes helpful to reduce cooling problems with those big engines.

With rising gas prices, we're going to see a shift towards more efficient airframes. The "high-performance" airplanes of tomorrow will be very motor-glider like. Performance will come from efficiency rather than high power. These clean machines will need large speed brakes (not little precise flight devises) for approach control and to reduce floating in ground effect. In the future, big speed brake, more than big engines, will indicate a high performance airplane.

PS - Once you get used to them, speed brakes are pretty awesome. They tame even the most slippery airframe and give you exact control of your approach.

Thanks,

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Originally Posted by SBaircraft

Today's "high-performance" airplanes are like old fashioned muscle cars... old fashioned airframes (1930's technology) with big engines. They are typically very draggy and don't need speed brakes for approach control or landing. . . .

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My old, straight-wing, Cherokee 140 fit that model, 150 hp, fixed pitch prop. With full flaps, the Cherokee 140 came down quite nicely and the cowl mounted, landing light stayed on the numbers. It also illuminated unlit obstacles on approach and a few night takeoffs. But slips at night pointed the landing light off the runway numbers at a time when other visual clues are 'in the dark.' In particular, I'm remembering two night slips, Tuscaloosa and a grass strip near the Finger Lakes, where a slip at night was needed on final. During the slip it was equivalent to not having a landing light.

What brought my question up was working on the landing light installation. One thought was to have the passenger side light pointed along the approach angle and the pilot side pointed down and offset based upon measured slip angle. But based upon my night flying experience, I want both lights pointing along the approach path. Ideally, pointed at both sides of the numbers with modest overlap in the center. The radiator cowl flap at speed-brake angle keeps the lights on the approach path while steepening the approach angle.

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Originally Posted by SBaircraft

. . . Once you get used to them, speed brakes are pretty awesome. They tame even the most slippery airframe and give you exact control of your approach.

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I have to add cowl flaps for the radiator anyway so implementation really comes down to length and how far down the linkage pushes the cowl flap / speed brake. It seemed like such a natural solution to a slippery airframe, I thought I'd ask if there were other examples . . . apparently not.

Bob Wilson

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Originally Posted by steveinindy

Assuming you do it correctly, . . .

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Not a problem, I am.

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Originally Posted by steveinindy

. . . If you don't mind my asking, can you PM me your address as I have a release form I would like you to sign before you pursue this any further.

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<SIGH>Take this up with the moderators, I have.

Bob Wilson

Bob: Love the drawings. It looks like the nose is being extended a lot. Have you looked at directional stability? All cross-sectional area ahead of the CG is destabilizing. To put it in perspective, the destabilizing effects of air data nose booms can be easily measured.

The speed brake also looks like it will be ahead of the CG ... another destabilizing surface. You would be surprised what a turned nose gear does to directional stability ... and it's on the center line of the airplane (yes, except the A-10). Perforating the brake will have a tendency to stabilize the surface and not change the (+/-) lift in that area.

Have you considered splitting the rudder?

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Originally Posted by WLIU

Here is the interaction between cowl flaps and speed brakes on an airplane that has both - When you want to descend fast you close the cowl flaps to keep the engine from overcooling and you extend the speed brakes to increase your drag. If you have ever seen and engine stop from being too cold (think winter extended glides at idle power) then you will want to keep your engine temps well into the green arcs on descents.

The two controls are used almost always oppositely at the same time.

Best of luck,

Wes

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This is the best way to describe why using cowl flaps as speed brakes is a bad idea.

Thanks Ron,

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Originally Posted by Ron Blum

Bob: Love the drawings. It looks like the nose is being extended a lot. Have you looked at directional stability? All cross-sectional area ahead of the CG is destabilizing. To put it in perspective, the destabilizing effects of air data nose booms can be easily measured.

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Yes but I'm not at that stage. I may wind up adding a dorsal to the rudder fin after completing getting the exact, firewall-forward configuration.

The planned, 128 lb engine replaces a 172 lb engine. But I won't know the final placement until I have the BSR (35 lbs), battery, engine (128 lbs), Ivoprop flight adjustable prop, and radiator. With the exact weights (including coolant and hoses,) I'll be able to calculate their final placements using similar weight from the existing cowl to estimate this part. Then I can fabricate the engine mount, and foam-and-fiber glass a cowl and radiator duct. I'll plan several mount locations for the battery so as it serves as movable ballast to get the final CG right at 58".

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Originally Posted by Ron Blum

The speed brake also looks like it will be ahead of the CG ... another destabilizing surface. You would be surprised what a turned nose gear does to directional stability ... and it's on the center line of the airplane (yes, except the A-10). Perforating the brake will have a tendency to stabilize the surface and not change the (+/-) lift in that area.

Have you considered splitting the rudder?

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Thanks for tips. I do have a 'loose' rudder but I haven't taken it apart yet to find out what it will take to make it tight. If I have to rebuild the rudder, adding area would be fairly easy at that time. But if I don't have to replace the rudder, a dorsal fin might provide a simpler answer. But funny you mentioned split rudder.

The original build had streamlined foam over the legs and wheel pants. I had thought about a 'split flairing' around the gear to use as speed brakes. Activated with the brakes, it would be complex but another approach potentially giving more yaw control. But angled in-ward, they might passively add yaw stability.

Angled slightly inward, 2-3 degrees, the leg flairings should act like 'toe', adding yaw stability. The forward leg would have more 'lift-drag' to turn the nose forward. The trailing leg would be at a lower angle, in a lower drag-lift profile. Located ~48" to either side of the CG, the force differential should help. This will be fairly easy to test.

Bob Wilson

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Originally Posted by bwilson4web

The original build had streamlined foam over the legs and wheel pants. I had thought about a 'split flairing' around the gear to use as speed brakes. Activated with the brakes, it would be complex but another approach potentially giving more yaw control. But angled in-ward, they might passively add yaw stability.

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Then you'll probably wind up with an unwanted nose-down pitching moment that'll vary with the amount they are open.

I believe that EZs use "split" rudders for speed brakes, too. In those cases the two rudders are independent (each can only travel outboard). I did a similar arrangement on my first homebuilt. One potential issue is that pilots that are nervous have a tendency to "secure" themselves by pressing on both rudder pedals ... which puts out the speed brakes. One way around that is to put a spring in the system so that it takes a little more opposing force to add speedbrake input.

Split surfaces for drag are also used on the Space Shuttle, F-16, A-6, F-22, F-117, etc.

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Originally Posted by Matt Gonitzke

Then you'll probably wind up with an unwanted nose-down pitching moment that'll vary with the amount they are open.

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Agreed and split, flairings would be a complex build.

Bob Wilson

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Then you'll probably wind up with an unwanted nose-down pitching moment that'll vary with the amount they are open.

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Which is exactly why I've been trying to warn Bob against this. If he wants a safe, reliable and predictable speed brake it's going to take a lot of testing (preferably CFD or wind tunnel as opposed to the "cross fingers and deploy" technique) and honestly I wouldn't be putting int on the underside of the aircraft. Something that deploys lateral (think the splitting tail cone speed brake of the BaE 146 or the side mounted ones on the F-86, etc which takes away the issue of inadvertent deployment if someone presses on the rudder pedals as Ron Blum describes) would probably be much less likely to cause a loss of control. The take home point in all of this discussion- which apparently Bob doesn't want to hear (neither did Dan Lloyd want to hear us telling him to take it easy and to not get in a rush; many of us in the hobby know where that got him)-is that what may seem like a good idea on paper or in our heads may not be the best solution to a problem, if a problem exists at all. Most cases of "I can't operate the airplane out of the fields I want to operate out of" are cases of:
1. Poor pilot technique/lack of skill/inexperience/poor decision making
2. Unrealistic assessment of the operational performance of an aircraft/pilot selected wrong aircraft for the wrong "mission"

Heavily screwing with aerodynamics of an aircraft is not the way to solve either of these problems, at least not unless you happen to either be or have access to a very experienced aerodynamicist.

I apologize if I'm a bit too pointed in my comments Bob. I just don't ever want a conversation I have with another builder to ever referenced directly or indirectly in another NTSB report so long as I live. Given that you seem to take any criticism as flippant or quashing a great idea I have this dreadful feeling that I'm seeing history repeat itself. You might not like my speaking up and recommending that you reconsider and you may not even be reading this, but in good conscience, I can't abide with remaining silent when I see someone engaging in questionable activities simply because I have a conscience that will not allow it.

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Agreed and split, flairings would be a complex build.

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Bob, if you'd like to see the diagram for the flight spoilers I have for the larger of my two designs which could be relatively easily modified to be used as a laterally deploying speed brake, I'm happy to share the basic design with you since it might solve the problem of needing to slow down without the issue of a pitching moment. They also include a fail-safe mechanism so that if the deployment cable fails, they stay retracted instead of popping open. I see the need for speed brakes in certain sorts of operations and my only beef is with where you want to put them. If I can help with a simple and possibly safer alternative, I have no problem doing so.

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What brought my question up was working on the landing light installation. One thought was to have the passenger side light pointed along the approach angle and the pilot side pointed down and offset based upon measured slip angle. But based upon my night flying experience, I want both lights pointing along the approach path. Ideally, pointed at both sides of the numbers with modest overlap in the center. The radiator cowl flap at speed-brake angle keeps the lights on the approach path while steepening the approach angle.

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Ah. I don't fly at night and so hadn't considered that.

The split rudder idea sounds like a winner.

... As for the landing light, here are a couple suggestions.

1) Mount it on a 2-axis swivel; it could turn into the relative wind all the time. (... please don't think about this too hard; it doesn't work in a crosswind)

2) I thought the only reason for a landing light is to be able to turn it off if you don't like what you see.

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Originally Posted by Ron Blum

... As for the landing light, here are a couple suggestions.

1) Mount it on a 2-axis swivel; it could turn into the relative wind all the time. (... please don't think about this too hard; it doesn't work in a crosswind)

2) I thought the only reason for a landing light is to be able to turn it off if you don't like what you see.

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LOL!

My plane, N19WT, is conventional geared so the landing lights on the ground would blind anyone on final while trying to taxi to the run-up area and do nothing for taxi-way visibility. So I'm working on a custom, eight LED configuration that will have two modes: anti-collision or taxi-mode controlled by a TI MSP430 controller.

There will be four on the top and four on the bottom of the fuselage. The fuselage top LEDs, just behind the cabin, will be angled 90 degrees apart, forward/back and left-right. The bottom LEDs will be 90 degrees apart handling front left and right quadrants and rear left and right quadrants.

In taxi-mode, the bottom, front quadrant LEDs will be bright and at 1,000 L throw enough light to see the taxiway out to the edges. This augments the red and green LEDs on the canard tips. The four top and two rear LEDs will have reduced intensity, just enough to help others see the plane on the ground. Forward taxi visibility is still a problem regardless of ambient light but the new engine, two vertical cylinders, is much narrower than the opposed, horizontal, four cylinder VW giving more forward visibility.

In anti-collision mode, the LEDs will cycle alternating top and bottom and around the plane. Each LED is rated at 1,000 lumens which exceeds the FAA 400 L requirement by a factor of two. Best of all, the average load will be ~11 watts.

The two landing lights will be 11 watts, 1,000 L each. With the Freshnel lenses, they will be awesome. I've already been testing the LEDs and lenses and they are painfully bright:
http://hiwaay.net/~bzwilson/dragonfl..._light_050.jpg
http://hiwaay.net/~bzwilson/dragonfl..._light_060.jpg

Last night, I cut the first, cone reflector out of aluminum sheet and clamped it. I still have to rivet it; cut and mount the Freshnel lense; mount a LED, and; fire it up to check the thermal characteristics. Initially, I'll use a junkbox LM319 to regulate the LED, 11V supply. Then I'll take it to Moontown or a dark, rural area after 'moon set' and measure the effective distance.

The new night light configuration will use:

• less power for the LED navigation lights, 0.26A, versus 2.3 A for the Grimes
• replace the front facing, xenons, .68 A. with 1 A. at 11 V., 360 degree collision lights that on the ground also serve as taxi lights
• adding two landing lights, focused and overlapping either side of the runway using ~2 A at 11V.

LED power is sensitive to voltage so I'll be using 92% efficient, auto-grade, DC-to-DC converters to step-down the aircraft, 12V bus to the well regulated, 11V, 0.9A each LED requires. The canard tip mounted, LED landing lights will each use a low-dropout, linear, ~0.5V, to handle the (I**2)R losses and avoid any parallel load issues.

Night VFR has a lot of advantages but the aircraft lights need to be done carefully and with attention to detail. The only thing not included is a tail-light but a stock LED will work when I get to that part of the rebuild.

Bob Wilson

Sounds like a great plan ... LEDs are changing the certification world, too. Ironically, the LED power gain (or loss depending on how you look at it) has also produced a "not-thought-about", undesirable side effect for those airplanes approved for FIKI ... the lenses are no longer anti-iced. Not an issue for your design.

Bob, quick question : which manufacturers are you using for the LEDs? I am trying to decide on them for my LSA. Ron I never would have thought of that. How would one overcome that? Perhaps like the little wires embedded in the rear window of cars?

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Originally Posted by steveinindy

I never would have thought of that. How would one overcome that? Perhaps like the little wires embedded in the rear window of cars?

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That is one way. Blowing hot air into the cavity is another. Having an arcraft design that handles the ice is another (or putting the light in a place that doesn't ice (like some airplane bellies). An advantage of LEDs is the potential for smaller frontal area. I have also heard of people using the "frame" as a heat sink for the electronics.

Ironically, this is not a big problem as airplanes large enough to have FIKI normally have extra "power" to deal with the situation, and those that don't have the power, normally aren't FIKI approved.

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Originally Posted by Ron Blum

Bob: I like the out of the box thinking; combining functions is always a good thing. But, the problem with cowl flap speed brakes is that when you most want them open (takeoff/climb) you don't want the added drag, and when you want the drag (coming down) you want the engine cowled to keep it warm. I also like Tony's comment: Plan ahead.

Nobody has mentioned slipping the airplane either. Oh, that's right, we don't teach using your feet anymore (tic).

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Those of us who enjoy making things work have four problems when that compulsion applies to airframes:

1. Complexity adds to the weight; controllable and retractable mean pounds,

2. Adding to your work load, even slightly, may be something you regret someday. Even I, who am, of course, the worlds greatest pilot, have tried to land with the wheels, prop, spoilers and my brain in the wrong place. Thank God not all three at once....... yet.

3. Don't know which Murphy's law it is but the more ways you give a device to break, the more often it will. Simple tends to be reliable (remember how the Vanguard rocket got us into trouble?).

4. You will enjoy the time you spend building the perfect machine but would you rather be flying with those hours? Should we admire your skill as a pilot or marvel at the machine you have designed? It's all good.

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Nobody has mentioned slipping the airplane either.

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Hey, I did!

:)

LED's with a frenel lens - brilliant thinking!

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Originally Posted by prasmussen

. . .
4. You will enjoy the time you spend building the perfect machine but would you rather be flying with those hours? Should we admire your skill as a pilot or marvel at the machine you have designed? It's all good.

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An engineer by training and background, I'm more interested in perfecting the machine. It is an occupational hazard . . . polishing the musket balls. <grins>

On a serious note, the 320 hours in my old Cherokee 140 were important:

• Relief from high-pressure job - when I reached the airport boundary, I hung up my work and home cares and totally surrendered to being the safest possible pilot.
• Managing limitations of old technology - often I was disappointed by the 1964 Cherokee technology.
• Night VFR - brilliant when it works but easily able to become 'serious' in seconds.
• Flight Service Station weather reports - most closed at night.
• Efficiency - 150 hp, fixed pitch prop, burning 8 gallons/hr, and only gets 100 mph. It climbed nicely with a good load but cruise was disappointing.
• Ignition - dual plugs fouled by 100LL.
• Electrical power - a generator using a relay voltage regulator that 'steamed' the battery.
• Carburetor - icing risk, manual mixture, required EGT to properly lean, and secondary, priming gas plumbing.
• Tube radios - they worked but gosh they burned a lot of power and ran so hot.
• Too much talk when we needed text - 1976-1980 voice radio, what a waste of bandwidth!
• ELT, instrument panel, . . . - there is a long list of that many have already been addressed.

Notice I didn't discuss VOR navigation since I never had a problem keeping on my true course even with a single VOR head. GPS was not available nor electronic maps. But it will be nice to enjoy what for me will be a technological leap.

As for flying, I'm expecting 3.8 gal/hr with a 600 mile range. If I really wanted to do something 'interesting', I suppose additional tanks in the cargo and passenger areas might add enough range to do a non-stop, transcontinental flight. If the electro-political issues could be worked out, using a series of 2,000 mile hops I should be able to reach the EU to visit their homebuilding shows and return. But that is in the future.

The one thing I don't want is to deal with a bunch of 'old technology' management issues.

Bob Wilson

Quote:

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Originally Posted by Frank Giger

Hey, I did!

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Sorry, Frank, I missed it. You are correct.

As for complexity (airplanes with speedbrakes), yes it does add a level of complexity ... and look at all the "world's greatest pilots" that have left the gear in the wrong position. But some airplanes have a hard time going down and slowing down at the same time. I would put Bob's airplane in this category.

Heck, even my Cessna P172D with 40 degrees of flaps was great; one could get it in anywhere. Flaps going from 30 to 40 only added drag. Note: Cessna got rid of the 40 degree flaps because people tried to "missed approach" climb with the airplane in that configuration. Personally, I would have the speed brakes as either "out" or "in" (no intermediate positions).

Many sailplanes on the other hand replace a throttle handle with a speed brake handle. It works the same way though ... forward for fast (brakes stowed) and aft to slow (boards out). In that case, some kind of speed brake device is required.

Bottom line: I agree with KISS.

Waking up this morning, I'm reminded of Burt, Dick, and Jeana and their round the world trip. In the beginning, everyone was a 'Burt' financing, fabricating and testing the voyager. Eventually, Dick and Jeana climbed in the Voyager and flew around the world while Burt provided ground support. Even that flight had to deal with technical problems including loss of the wing tips on takeoff yet they pulled it off.

So it isn't an either build or fly choice but first comes the build and then comes the flying. Like any flight, there is no guarantee that new (or old) technology won't have problems but a through understanding gives us choices.

Bob Wilson

Bob: Well put, as I look above, behind and to my right in my home office to see an autographed picture of the "Voyager". The photo was taken before the flight as both winglets (fuel vents) were still intact.