Hoerner tips

[atypicalguy]

Anyone here put them on a metalized 140 wing? Thanks.

[2066]

Having seen quite a few over the years, both "metalized" and 140As, I haven't noticed any with Hoerner tips. ...not saying it hasn't been done or that some existing tips don't encompass just a bit of the Hoerner design...but, I haven't noticed. Mac

[atypicalguy]

Here is this plane with sort of marginal power to weight and climb performance. The Hoerner tips are pretty widely acknowledged to give a few percent improvement in climb and top speed. The people who make them have an STC for the 140A, so I would think one would be able to obtain some sort of approval for metal wing conversions also. The net weight increase, if any, cannot be much. It has to be one of the most cost effective things one could do for this airframe in terms of performance, apart from replacing the battery with EarthX. So far I have not seen many of those, either, but they are far more unproven in terms of reliability and performance than wingtips.

[2066]

The idea is intriguing, certainly. The issue with metalized wings may be that there are several STC'd and, probably, some "field approved" installations, so each may well be sufficiently different to adapt and gain "approval" for the Hoerner kit? It seems that we all want to "improve" the design and performance of the old 120s/140s and, yet, if we pause and take a good look we may find that they're pretty well designed "as is". "As is", of course, would mean keeping them as light as possible and in excellent condition all 'round. A major "upgrade" that's been applied regularly over the years is to install "more horsepower" -- that can work reasonably well with changing the C85 for an 0200. The Lyc (some STC'd) upgrades can work, too, but diminishing return may come easily in terms of weight increase(Ex: One member years ago installed a BIG Lyc in his A with offsetting weight in tail and his wife could "legally" only weigh 11 pounds with the new w & b ). In any event, plz keep us posted as/if you pursue the concept. Mac

[8102]

I'm not sure about the 140A wingtips, but the 150 wingtips are just made of plastic and attached to the wing with screws into the rib. Replacing the 150 wingtip with a different design is straight forward, remove the retaining screws pop of the existing wing tip and install the new wing tip using the reverse procedure. Probably could be done in less than an hour for both tips. The 140 wing, whether metalized or not (the wingtip is already metalized), has a fair amount of structure that would have to be cut out and replaced with the new tip along with a revised mounting technique including potentually new structure. Not saying it cannot not be done but it's certainly not as straight forward as replacing a 150 wingtip.

Gregg

[2066]

I'm not sure about the 140A wingtips, but the 150 wingtips are just made of plastic and attached to the wing with screws into the rib. Replacing the 150 wingtip with a different design is straight forward, remove the retaining screws pop of the existing wing tip and install the new wing tip using the reverse procedure. Probably could be done in less than an hour for both tips. The 140 wing, whether metalized or not (the wingtip is already metalized), has a fair amount of structure that would have to be cut out and replaced with the new tip along with a revised mounting technique including potentually new structure. Not saying it cannot not be done but it's certainly not as straight forward as replacing a 150 wingtip.

Gregg

Greg, do you see potential for any structural issue concerns due to the additional "lift" provided by the Hoerner tips? While my truly uneducated guess is no, I'm aware that the FAA may look first for reasons not to approve some mods. Mac

[8102]

As far as the load on the spars and struts, I doubt there would be any significant structural issues though adding lift at the wing tip is the worst case from a bending moment perspective. I'm sure the FAA would want to see the analysis to prove it. The bigger concern would be the local loads at the wing tip and how the new tip is tied back into the existing wing structure.

Personally, I doubt the increased performance would be worth the effort. Say you get a 1% improvement in top speed, so it goes from 105 mph to 106 mph. I would rather spend my dollars looking at ways to reduce weight (including my own weight) to both increase useful load and climb performance. Plus I'm a purist, I like the design as Cessna made it 70+ years ago. If you want a faster airplane then buy a faster airplane.

Gregg

[2066]

Greg wrote: "Personally, I doubt the increased performance would be worth the effort. Say you get a 1% improvement in top speed, so it goes from 105 mph to 106 mph. I would rather spend my dollars looking at ways to reduce weight (including my own weight) to both increase useful load and climb performance. Plus I'm a purist, I like the design as Cessna made it 70+ years ago. If you want a faster airplane then buy a faster airplane."

...couldn't agree more! The purist tendency doesn't keep me from taking advantage of "new" weight reducing opportunities, like 4.25 lb. "alternator", small starter, removing outdated vacuum stuff, etc. and etc.. The thing with my own weight is a different story, but there's yet good intentions . Still, when you really look at the overall design and performance it's amazing how well those "old" engineers did in building us a "modern" aircraft that lasts, is relatively simple, and really competes with a lot of the spiffy new "comparable" ones. (At my age, though, I am thinking that the 1 mph increase could come in handy with need for a quick potty break ) Mac

[a64pilot]

I can promise you after having done significant testing on other aircraft, that there is not anything you can put onto the wing tip that will give you any improvement at all, but it’s likely you will lose performance
Take the Mooney for example, one of the most efficient aircraft there is, and for years the wing just ended, no kind of tip.
On the 1981 J Model an unusual up swept tip was added by Lopresti. Pretty much every time how much performance increase there was came up. he changed the subject.
The truth is that there is no performance improvement at all, so they started claiming it enhanced aileron response, but in truth it’s a styling add or maybe got people talking etc.

Maule went from a droop tip to a Horner type tip in around 84 or so, they did it as the different wing tip allowed a longer aileron while keeping the long flaps and kept the wing span the same as any increase in wing span meant the FAA would make them pull the wing, but performance didn’t change,I think it actually hurt it slightly
Only time you can get something from a wing tip design is if an aircraft cruises at high angles of attack and a much higher speed than we do.
In fact the elliptical wing was considered superior for a long time, it’s worst drawback being that it was tough to build and our current wing tip does make the wing sort of an elliptical wing

[8224]

A good friend of mine was president of the 180/185 club for several years. One year at their annual convention they asked the old gentleman who had been the head of the design team at Cessna for the 180/185 to be the speaker at their dinner. Apparently he gave a very good talk and at the end asked if there were any questions. One fellow asked,”do any of these new STCed speed mods really work”? The old gentleman scratched his head and gave the question a period of thoughtful consideration. Then he answered the the question. To everyone’s surprise he said yes they do! He said “Those mods cost a lot of money. Everyone knows that a reduction in weight increases performance. The owners billfold is much lighter so there really is an increase in performance”. In my opinion these old planes were designed about as well as any plane ever was and the best thing we can do is keep them as light as possible. I am restoring a 47 C-140 and take every opportunity to save weight.
Steve