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Planing-tail seaplane project. Is it possible?

Posted By:
Marco Lucchesi
3
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#1 Posted: 2/23/2011 06:09:21

Hello, I'm a student of aerospace engineering and for my graduation thesis i have to do a study on a hull for an amphibian ultralight aircraft.

Looking around for previous studies I have found only NACA reports. In the more recent ones (50s) we can find studies on an hull called "PLANING-TAIL HULL" characterized by 2 point of contact during planing phase : 1 near the step like conventional hulls and 1 at the final part of afterbody. This solution appear to have great advantages regarding porpoising, providing a huge trim range where we have stability.

I would like to know if someone have experience on this kind of hull and if you think this configuration could present some operating disadvantages (I'm not a pilot and don't have direct experience).

Looking for newest seaplanes, I found the Icon A5; has anyone ever seen this plane takinf-off or flown with it? Watching videos on website it seems to take-off without an elevator angle increase; Do you know if its hull have 1 or 2 point of contact during planing phase?

Thank you.

Marco



James Feldmann
Homebuilder or Craftsman
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#2 Posted: 2/24/2011 20:36:58

The Seawind amphibian has that type of hull.

 

Jim



Torello Tacchi
Homebuilder or Craftsman
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#3 Posted: 2/24/2011 20:50:17

Marco,

My  buddy and I fly his Searey Amphib (hull type), but have not experienced any bad habits in the water, save if it was a "poor" landing.  The Searey also flies off the water easlily, and performs any water proceedures without any poor qualities.

Progressive Aerodyne is it's maker and I'm certain Kerry Richter woul be happy to give some expert information on teh subject.

Torello Tacchi



Marco Lucchesi
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#4 Posted: 2/25/2011 04:42:23

Thank you for answers. 

James, do you have direct experience on Seawind? I saw it during my researches but I think this plane didn't have great success; do you know why? Are there some operating problems with this configuration? I don't know, something like visibility, longer take-off run? On web I could find just promotional videos (dated videos) and can't understand vary well planing behaviour from these.

Torello, i think SeaRey is a very interesting seaplane with great stability! But in videos, i can see it don't have planing tail hull but a conventional one with just 1 point of contact during planing. What do you mean with "poor landing"? (as i said i'm not a pilot) cause i'm very interested in speed and trim landing ranges (that are the greatest limit for conventional hulls)

Best regards,

Marco



Grant Smith
Homebuilder or Craftsman
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#5 Posted: 2/28/2011 14:12:19

The step type hull was developed for aircraft so that they could rotate for takeoff. Some aircraft are designed so that they do not need to rotate for takeoff. The tandem landing gear of the B-52 is an example.

I am not familiar with the data for the "tail plaining hull" you refer to but it sounds like it would prevent rotation in exchange for limited porposing. There would be a trade off of one against the other.

Weight Shift Control "Trikes" benifit from the type of hull you are suggesting for two reasons. There is no elevator control to control pitch of the fuselage and there is no need to rotate. Without the tail dragging float, CG range of the fuselage becomes very limited and porposing is a problem.

If you can post any information on the tail-plaining hull I would like to review it.

I am currently working with a seaplane that has a unique hull design that has considerable model testing and I have been impressed with it's operation. It is not my design but I would recommend that you incorporate some of its features in your proposal.



Grant Smith CFI
Marco Lucchesi
3
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#6 Posted: 3/1/2011 03:58:15

Hi, where I can see this new hull design you are writing of?

About planing-tail hull I read NACA reports on www.NASA.gov, you can easily find about 15 reports, here some links:

http://naca.central.cranfield.ac.uk/reports/1946/naca-tn-1062.pdf

http://aerade.cranfield.ac.uk/ara/1946/naca-tn-1101.pdf

 

From my researches we can say that:

>Planing tail pro:

- great advantage in porposing range

- planing speed lower than conventional hull

- minimize trim range during take-off run (almost costant)

>planing-tail disadvantage:

- high trim in take-off run, reduced field of vision during this critical moment.

- no rotation at take-off means or highest speed at take-off (with longer run) or best wing setup for take off but not optimal for cruise (I think, but a sperimental test should verify that last point)

>Conventional hull pro:

- low trim during plan

-rotation on Take-off  means possibility for low  take-off speed, and  wing best setup imposed by cruise.(Here should be great to understand how long would be the run lenght for a conventional hull to reach minimum TO speed compared to the one for a planing-tail hull with wing setted up for cruise ).

>Conventional hull disadvantage:

- low stability range

- elevator control required for balance during planing run.

Best regards,

Marco



Grant Smith
Homebuilder or Craftsman
135
Posts
7
#7 Posted: 3/1/2011 05:19:18

Thanks Marco.

The aircraft is a single seat light sport seaplane known as the Sea Era and is not well known yet. It has been flown about 4 times in the last year. The designer does not do much on the computer so information is not easily transmitted. I will send a personal message for additional contacts.

Grant



Grant Smith CFI