Air Dams for wheel wells.
- Thread starter NC74392
- Start date
I remember reading an article that I got from the Bellanca club, about a university doing a study on the wheel wells.... they installed brush seals and gained a whole bunch of speed.... I'm sure Larry or Bob would know about that article.... I remember seeing them towing the cruisair behind another plane to get a true drag reading, as they just took a shackle and attached it to the prop flange.... very interesting reading!!
John H.
John H.
greetings!
the article several of you have mentioned was by the great aerodynamisist august raspet and was published in the eaa "sport aviation" february, 1957. the title is something like: "drag reduction of a light personal aircraft". it is available from eaa for about $5 for copying/mailing. very interesting article and outlines some general cleanups possible on the 14-13 cruiseair aircraft. hope this helps!
blue skies,
vic & N522A
the article several of you have mentioned was by the great aerodynamisist august raspet and was published in the eaa "sport aviation" february, 1957. the title is something like: "drag reduction of a light personal aircraft". it is available from eaa for about $5 for copying/mailing. very interesting article and outlines some general cleanups possible on the 14-13 cruiseair aircraft. hope this helps!
blue skies,
vic & N522A
NC74392
New member
Is this the same speed study the BCC offers? I have a copy of that but it doesn't seem to mention specific technical installations.
I was thinking an air dam about two inches high angled about 45 degrees might be enough, but I don't know the formula for checking my guess. Maybe I should take a clue from the Wright Brothers and build a small wind tunnel?
I was thinking an air dam about two inches high angled about 45 degrees might be enough, but I don't know the formula for checking my guess. Maybe I should take a clue from the Wright Brothers and build a small wind tunnel?
Jonathan Baron
New member
I think you're referring to the Lambert speed study. My mechanic in Arlington, WA, showed it to a fellow who develops speed mods for a living (there are several in Washington State) and it gave him a good chuckle. After some analysis he determined that if I had a faring behind the wheels that extended to the flaps I might get 3mph more. Needless to say, I passed.
There was a fellow who developed a complete clam shell door mod for Cruiseairs. He also performed several other modifications - micro ballooning the wings, putting the position lights into the wing tips (carving out a notch and covering it with plexiglas), embedding the horizontal stabilizer position light, and such. It was claimed he achieved a max level speed of some 176mph. Then he moved to Mexico and vanished from view.
Another fellow at Santa Paula wanted to develop an STC for the clam shell doors for Cruisemasters, but perished in a test flight aimed at testing their integrity at Vne. I believe it was a prop separation accident and had nothing whatsoever to do with the doors. No one pursued the STC effort further. I'm told the molds are still laying outside at Santa Paula. I have an uncut pair of these "doors" (they cover the gear and the wheel well) that came with my 14-19 but I know I'll never use them. You'll see them from time to time on Cruiseairs.
To my mind it comes down to this. Some triple tail owners have much in common with the Swifters - they don't object and, in fact, embrace modifications to their airplanes. Some prefer original, and don't want farings, carved up Cessna 150 wheelpants, or anything of the kind added as they feel it spoils the airplane's looks.
Fact is that with handmade aircraft like ours, adding decades of use and variations in storage environment into the equation as well, the speed differences between individual examples are perhaps more pronounced than any other types in general aviation. Your Bellanca is as fast as your Bellanca is. There are so many qualities to Cruiseairs and Cruisemasters that distinguish them from the pack. Plus or minus a few miles per hour, to me, really doesn't matter a whole lot.
Jonanthan
There was a fellow who developed a complete clam shell door mod for Cruiseairs. He also performed several other modifications - micro ballooning the wings, putting the position lights into the wing tips (carving out a notch and covering it with plexiglas), embedding the horizontal stabilizer position light, and such. It was claimed he achieved a max level speed of some 176mph. Then he moved to Mexico and vanished from view.
Another fellow at Santa Paula wanted to develop an STC for the clam shell doors for Cruisemasters, but perished in a test flight aimed at testing their integrity at Vne. I believe it was a prop separation accident and had nothing whatsoever to do with the doors. No one pursued the STC effort further. I'm told the molds are still laying outside at Santa Paula. I have an uncut pair of these "doors" (they cover the gear and the wheel well) that came with my 14-19 but I know I'll never use them. You'll see them from time to time on Cruiseairs.
To my mind it comes down to this. Some triple tail owners have much in common with the Swifters - they don't object and, in fact, embrace modifications to their airplanes. Some prefer original, and don't want farings, carved up Cessna 150 wheelpants, or anything of the kind added as they feel it spoils the airplane's looks.
Fact is that with handmade aircraft like ours, adding decades of use and variations in storage environment into the equation as well, the speed differences between individual examples are perhaps more pronounced than any other types in general aviation. Your Bellanca is as fast as your Bellanca is. There are so many qualities to Cruiseairs and Cruisemasters that distinguish them from the pack. Plus or minus a few miles per hour, to me, really doesn't matter a whole lot.
Jonanthan
NC74392
New member
I guess I was thinking it would be a really easy thing to do and it would cut down on drag a little. I have all the fabric off the wings anyway so it's just not that much trouble IF I know what I'm after.
Something as complex as the gear covers on, say, a Seversky P-35 is getting a bit silly, but a simple air dam? I was thinking more in terms of something that would encircle the wheel well 270 degrees and leave the rear of it open. Something that wouldn't stick out as much as a chopped-up Cessna wheel faring, but would keep high-speed air out of the back of the well.
Too much to ask for huh?
Something as complex as the gear covers on, say, a Seversky P-35 is getting a bit silly, but a simple air dam? I was thinking more in terms of something that would encircle the wheel well 270 degrees and leave the rear of it open. Something that wouldn't stick out as much as a chopped-up Cessna wheel faring, but would keep high-speed air out of the back of the well.
Too much to ask for huh?
Jonathan Baron
New member
Don't let me stop you, David - just one fella's opinion is all.
Due to what I consider sheer ignorance, ours are not high value classics. Thus mods don't make a dollar difference and you can take that out of the consideration equation.
It's your airplane, man. Heck, if you come up with a low profile mod that gives your airplane a few more mph - and the wing is already apart - that would be cool. I sure most of us would at least contemplate something to mitigate the airflow separation behind the exposed portion of the wheel.
Jonathan
Due to what I consider sheer ignorance, ours are not high value classics. Thus mods don't make a dollar difference and you can take that out of the consideration equation.
It's your airplane, man. Heck, if you come up with a low profile mod that gives your airplane a few more mph - and the wing is already apart - that would be cool. I sure most of us would at least contemplate something to mitigate the airflow separation behind the exposed portion of the wheel.
Jonathan
hey guys!
i've seen fotos of an early 14-9 and one can see a small fairing aft of the wheel well that would obviously fair in the wheel in the retracted position. so i suppose guiseppe was thinking about this very thing early on.
the fully enclosed clamshells that jonathan speaks of are known as "kennedy fairings" (made by mr. kennedy, i guess) and the tooling is rumored to be around southern california. drew peterson has a set on his 14-19-2 (260hp, IO-470). don't know about specific speed gains, though i've been told it's difficult to keep them rigged.
the flight test accident that occurred testing the kennedy fairings had to do with blade separation on the Aero-Matic prop. the geniuses at the faa required the pilot to dive to Vne in spite of the fact that everyone knew it would take the prop beyond it's certificated rpm. something to consider whenever the local faa requires something of you in a test flight program.
jonathan makes an interesting point about the parallel between the bellancas and the swifts. some like 'em stock, some like the mods. guess it just depends on where your heart and wallet are. anyway you slice it, it's still a superior light aircraft. and, as jon says, "...we sir, are lucky men!"
blue skies,
vic & N522A
i've seen fotos of an early 14-9 and one can see a small fairing aft of the wheel well that would obviously fair in the wheel in the retracted position. so i suppose guiseppe was thinking about this very thing early on.
the fully enclosed clamshells that jonathan speaks of are known as "kennedy fairings" (made by mr. kennedy, i guess) and the tooling is rumored to be around southern california. drew peterson has a set on his 14-19-2 (260hp, IO-470). don't know about specific speed gains, though i've been told it's difficult to keep them rigged.
the flight test accident that occurred testing the kennedy fairings had to do with blade separation on the Aero-Matic prop. the geniuses at the faa required the pilot to dive to Vne in spite of the fact that everyone knew it would take the prop beyond it's certificated rpm. something to consider whenever the local faa requires something of you in a test flight program.
jonathan makes an interesting point about the parallel between the bellancas and the swifts. some like 'em stock, some like the mods. guess it just depends on where your heart and wallet are. anyway you slice it, it's still a superior light aircraft. and, as jon says, "...we sir, are lucky men!"
blue skies,
vic & N522A
Jonathan Baron
New member
That's right, Vic - I nearly forgot: by many accounts it was difficult to keep them in rig and if they didn't "clam up" properly you didn't get any benefit. A clam shell arrangement, as you know, was developed at the Alexandria factory for Vikings which ultimately brings us back to the same point. The speed range among Vikings is wide as well.
No plug intended, but this entire tale can be gleaned if you purchase the reprints of an earlier Bellanca newsletter from the Bellanca-Champion Club. They also have that early speed study, and other interesting stuff. There are two volumns of reprints actually. The earlier package of newsletter reprints in more pertinent to us. The later one is sporadic, is largely composed of member letters, and is more Viking focused.
On a related matter, I'm sure you've all seen the speed mods for Pipers from Knots2U. Having spoken with many Piper lovers, the consensus is that ultimately the cost is one thousand dollars a knot, despite the claims. It's not that the LoPresti folks are a liars; it's just that there is considerable variation among examples in that fleet as well, plus speed mods are not directly cumulative. You cannot add up the numbers of all the mods and get the sum of that when they're installed.
For Piper retracts, the highest speed increase claim is <drum roll> the farings that go behind the uncovered area where the wheels retract. Yes, I'm torturing David
Jonathan
No plug intended, but this entire tale can be gleaned if you purchase the reprints of an earlier Bellanca newsletter from the Bellanca-Champion Club. They also have that early speed study, and other interesting stuff. There are two volumns of reprints actually. The earlier package of newsletter reprints in more pertinent to us. The later one is sporadic, is largely composed of member letters, and is more Viking focused.
On a related matter, I'm sure you've all seen the speed mods for Pipers from Knots2U. Having spoken with many Piper lovers, the consensus is that ultimately the cost is one thousand dollars a knot, despite the claims. It's not that the LoPresti folks are a liars; it's just that there is considerable variation among examples in that fleet as well, plus speed mods are not directly cumulative. You cannot add up the numbers of all the mods and get the sum of that when they're installed.
For Piper retracts, the highest speed increase claim is <drum roll> the farings that go behind the uncovered area where the wheels retract. Yes, I'm torturing David
Jonathan
Jonathan Baron
New member
Here's that Piper gear lobe faring. Note that the design, as my expert guy claimed I'd need, goes all the way to the flap. Of couse, this photo is of an airplane with unconventional landing gear, thus the distance from wheel well to flap is shorter.
Jonathan
http://knots2u.com/images/wpe42.jpg
Jonathan
http://knots2u.com/images/wpe42.jpg
NC74392
New member
That Seversky P-35 gear faring looks better and better all the time. It's complex though- you have a clamshell affair where the rear faring lobe crosses the flap gap. The gear leg faring is actually pretty simple all things considered. Here's a link:
<http://www.wpafb.af.mil/museum/research/p35-3.jpg>
Note the tire still sticks out below the faring when retracted.
DD
<http://www.wpafb.af.mil/museum/research/p35-3.jpg>
Note the tire still sticks out below the faring when retracted.
DD
NC74392
New member
I understand why the faring decreases drag behind the wheel when retracted. The tire acts as the leading edge of the aerodynamic shape and the faring completes the smoothe flow. The part I don't understand is the area to the sides of the tire that are open to the world. It still seems air pressure would build up in the wheel well without some sort of deflector in front of the cutout. In WWII the B-17F waist gunner window had an air dam running top to bottom on the leading edge of the window frame. This was to deflect the air away from the gunner as well as cut down on drag created by the open windows. This is what got me thinking about this in the first place. Another picture. The air dam is the narrow strip in front of the window. It was positionable and is retracted in this picture.
<http://www.ratol.fi/~tmannine/pics/bb_waist_general.jpg>
<http://www.ratol.fi/~tmannine/pics/bb_waist_general.jpg>
Drew Peterson
New member
NC74392 said:
I currently have a set of molds for the gear fairings on my cruisemaster. I am in the process of lining up a small production run at this time. This has come about due to the help of several Bellanca- type people. I would like to make these as affordable as possible-my cost. These fairings will not have the small doors due to the fact that they can be difficult to keep in rig and their need is questionable.
I have never flown my Cruisemaster with the fairings off, so I am unable to give any info as to their speed value. I simply like the way they clean up the gear. On my airplane I have a small metal fairing that attaches on the under side of the leading edge of the wing just ahead of the top of the landing gear leg. From this a half circle flange protrudes down to smooth the airflow around the top of the landing gear leg when retracted - hence, your air dam.
I do believe that the fixed fairing attached to the underside of the wing just behind the the tire (when the gear is retracted) may produce the greatest drag reduction.
If anyone is interested in the fairings please let me know as I would like to keep the cost as low as possible.
Jonathan Baron
New member
Indeed, Drew - as I said, the expert who looked at my 'Master said that the best mod would be a faring behind the wheel. It would have to extend to the flap, however, and he predicted 3mph more speed. He rejected the notion of metal attachments to redirect airflow around the wheels, but it was just one opinion, albeit a specialist's.
It's all a question, IMO, of personal taste. To me, the original gear is as the triple tails - part of the distinctive look of the airplane.
I think the best compromise for one and all would be a faring behind the wheel that's as inconspicuous as possible.
What's really needed in this dicussion at this point is data - hard numbers. It's not reasonable to ask you to pull off your gear farings and perform before and after tests. However, I believe there are some affordable wind tunnel simulation programs available. The hard part would be creating an accurate Cruiseair and Cruisemaster shape. One might need drawings to accomplish that. I will investigate this and let you all know what I find. Or, if someone reading this knows, please share
Jonathan
It's all a question, IMO, of personal taste. To me, the original gear is as the triple tails - part of the distinctive look of the airplane.
I think the best compromise for one and all would be a faring behind the wheel that's as inconspicuous as possible.
What's really needed in this dicussion at this point is data - hard numbers. It's not reasonable to ask you to pull off your gear farings and perform before and after tests. However, I believe there are some affordable wind tunnel simulation programs available. The hard part would be creating an accurate Cruiseair and Cruisemaster shape. One might need drawings to accomplish that. I will investigate this and let you all know what I find. Or, if someone reading this knows, please share
Jonathan
Jonathan Baron
New member
Well, I searched high and low. Problem is that wind tunnel simulation software or any simulation software for aircraft design is serious business created for a very limited audience. Thus it can be extremely expensive.
The best deal I found was $750 but it's a good package for homebuilt aircraft designers. It's more than I can afford at the moment as I've spent every spare cent these past 30 months getting my 14-19 the way I want it.
Here's the link to to software:
http://www.darcorp.com/Software/AAAlite.htm
In short, the hard numbers will be a long time in coming in this discussion, alas.
Jonathan
The best deal I found was $750 but it's a good package for homebuilt aircraft designers. It's more than I can afford at the moment as I've spent every spare cent these past 30 months getting my 14-19 the way I want it.
Here's the link to to software:
http://www.darcorp.com/Software/AAAlite.htm
In short, the hard numbers will be a long time in coming in this discussion, alas.
Jonathan
hey jon, drew & all,
having worked for several airframers over the years i know that aerodynamic simulation software (more frequently known as "CFD": Computational Fluid Dynamics) is not only expensive, but "challenging" to learn and apply effectively. the best i've seen for "our crowd" was a series of spread sheets developed about 6 years ago by john roncz and published in sport aviation. not real sophisticated, but easy to apply and "good enough for the girls we go with".
barring that, i'd be willing to develop some baseline performance numbers with N522A once i get up flying again. the airframe is very stock and relatively clean and straight. current W&B shows around 1630# but i will be weighing the airplane before i fly again, so this will be verified. i have some freinds who work as flight test engineers and might be able to help me "do the data". this would help get a real world performance baseline for the 14-19 and then the benefits of various drag clean-up mods (and horsepower increases!) could be evaluated objectively.
hope this helps,
vic & N522A
having worked for several airframers over the years i know that aerodynamic simulation software (more frequently known as "CFD": Computational Fluid Dynamics) is not only expensive, but "challenging" to learn and apply effectively. the best i've seen for "our crowd" was a series of spread sheets developed about 6 years ago by john roncz and published in sport aviation. not real sophisticated, but easy to apply and "good enough for the girls we go with".
barring that, i'd be willing to develop some baseline performance numbers with N522A once i get up flying again. the airframe is very stock and relatively clean and straight. current W&B shows around 1630# but i will be weighing the airplane before i fly again, so this will be verified. i have some freinds who work as flight test engineers and might be able to help me "do the data". this would help get a real world performance baseline for the 14-19 and then the benefits of various drag clean-up mods (and horsepower increases!) could be evaluated objectively.
hope this helps,
vic & N522A