Flaperon Design mixer help 1

[awparran]

Hi:

I posted a thread in the AERODYNAMIC section seeking help on a flaperon design. I have not received a response, so I designed my own. I think it looks pretty slick, but looking slick does not mean very much in the air where it really counts.

I am not a structural engineer, in fact I am not an engineer at all but I have built several aircraft of other designs. I have decided to design, build and fly my own aircraft. I have studied several designs and feel comfortable with mine, including the flaperon and mixer controls.

I am using AutoCAD 3D. I have put my flaperon design on paper, but am hesitant to do so in AutoCAD until I am sure that it will meet the design loads it will carry.

I would like to present my design to someone without a vested interest to give an unbiased opinion. I only ask that this individual keep my design confidential until I am ready to present it to the Recreational Aircraft Association, and/or the Experimental Aircraft Association. If my design is unique enough, I might apply for a patent.

Thanks in advance.

 

[plasgears]

I believe it has been done before. I tripped over it recently in my readings in the EAA Aerocrafter. It has been applied to high-wing STOLs. The idea is OK, but the design needs to be applied carefully. There should be sufficient elevator to control the airplane over a range of speeds. Use the old method of comparative proportioning; study present designs.

 

[awparran]

I guess I must have misstated my intentions. I understand the flaperon design has been done before. In fact it was used on the Junkers Ju-87 in World War II.

I have studied the other designs as found on the Murphy Rebel, Kitfox and the Zenithair CH701/801.

My design incorporates ideas from each, but as stated I am not an engineer. Either I have over designed my setup, or I have under designed it. Over design means too much weight and I'll never get off the ground. Under design, well,, means opps! And as you are aware, there are very few pilots that have lived to tell about an opps!

So I am just asking that someone look at what I have and say it will or will not work.

 

[SWComposites]

How much are you willing to pay for this design review?

 

[Sparweb]

Tparran,

Assuming this is a "homebuilt", at some point you will have to show the work to an EAA tech counsellor, or to the inspector who performs your pre-covering inspection. Once it gets in the air, all your friends (and EAA members, too) will start climbing all over it. If you intend to keep your flaperon a secret until you have a patent in place, you may not fly your bird for a very long time. Since your purpose is to create a nice airplane, you may not enjoy the tedious process of applying for a patent, either. Do you intend to produce this airplane as a kit?
The first criteria for evaluating a design are the loads it must support. Next is the reliability, and modes of failure. Even if you're not an engineer, you can understand the principles and do the math.

Steven Fahey, CET
"Simplicate, and add more lightness" - Bill Stout

 

[awparran]

I was mostly joking about the patent. Too much of a hassle.

I just want to get flying.

No I have no intention of producing a kit. That too is a hassle, and the liability is not worth it.

This has been my dream of many years and as stated, I have built designs of others. There are others with far less understanding of areodynamics and aeronautics than myself, yet they have produced their own designs and flown them successfully. So the question is, Can I do it too?

My design is not radical. Just standard metal and wood/composite materials. I have studied several designs and combined what I like of each. This is not a record setter, nor a flying lawnchair either. My design is a mid-wing, tandem two seater - pusher. 120 Kts cruise, 1800 lbs gross is the projected max weight. 26 foot wing span, 25 feet in length.

I know I can build it, and I am willing to try, otherwise what are dreams for?

 

[aviat]

If you do a patent search at the US patent office under flaperons you will find 85 previous patents, with many more with prior art. Reading these will give you ideas of how others have accomplished the mixers.

According to NACA Report #541 Junkers used full span flaps as early as 1925. Note NACA did not call them flaperons. As far as I can determine, the first to use them in North America, was the Nordyne Norseman (1930’s), followed by De Havilland Canada series of airplanes. These were STOL type aircraft with mechanical mixers on flap/ailerons, and on some, a flap elevator trim interconnect, which is needed to counteract the large pitching moment when full flaps are selected. Some fighter and radio-controlled airplanes also use flaperons, but the purpose there is for improved move ability i.e. faster turning rate.

As for your question regarding someone looking at your design, there are some ex De Havilland Canada engineers that do consulting work on these type of systems, one being Chris Heintz from Zenith.

 

[awparran]

I wrote to Mr. Heintz a month ago he is most likely very busy and has not responded so I will try De Havilland Canada, and or Murphy Aircraft since they're right down the road in Chilliwack, BC about 300 miles as the crow flies.

 

[awparran]

Maybe some one can answer this question(s).

My design calls for nylon bearings, fabricated to fit into 2" O.D. 4130 tubes. Since these involve very low speed rotations, but at times might call for excessive forces, is this a good material or should I use teflon?

Is there another product that has the same low friction properties?

I am looking at wear, temperature extremes, rotation friction, etc.

 

[Sparweb]

The plane sounds fun and unique.

How about Delrin? That's DuPont's specific product name, and I think the material is generally referred to as acetal resin. Handy stuff.

If you really want to pursue the de Havilland route, you could always try to make arrangements with Bombardier's product support group and take a trip to Toronto. They might expect you to pay by the hour for the privilege, and no photocopying, please.

Murphy might be a better option, but they are probably very busy, too.


Steven Fahey, CET
"Simplicate, and add more lightness" - Bill Stout

 

[awparran]

Thanks SparWeb:

I did a Google search and came back with a lot of hits. I have bookmarked several for later reading.

I have plans of visiting my home in Indianaplis later this year, so Toronto is not too far out of the way.

Darn! There goes my cellphone camera idea.

As for Murphy, I have dropped in on them many times unannounced, since it is on the way to Vancouver and Seattle. They have let me see their factory and their latest projects, tools, etc. They are some really cool people. Very friendly. Everyone from the front office administrator, the owner(s), and even the shop people took time to explain a process or an idea.

This is not a promotion for them, only my experience of how I was treated when I was there.

 

[Sparweb]

I finally made the connection and realized there is an important tip to pass on to you: Richard Hiscocks contributed greatly to the conception and development of the DHC Beaver and Otter aircraft in the late 40's and 50's. In later years he collaborated with Darryl Murphy on the Rebel. Hiscocks has since passed on, but he published a book named "Design of Light Aircraft" that needs to be on your shelf. See my FAQ for details.

On the second topic, Delrin, I have just had some experience machining a set of parts, that I feel like passing on: As a replacement for phenolic ("micarta") parts, we've tried switching to delrin as a less nauseating alternative. However, the following problems have been encountered: Cutting a large cut-out in a plate caused a significant change in dimensions. What started as a 7" hole in an 8" wide plate, became an ellipse with a 7" major axis and 6.982" minor axis when unclamped from the lathe. That's a 0.24% change. Are other plastics like that? I'm afraid my experience predominantly with aluminum and steel hasn't prepared my for these unexpected demons.


Steven Fahey, CET
"Simplicate, and add more lightness" - Bill Stout

 

[awparran]

Interesting to say the least.

I am off tomorrow and Friday (My Saturday and Sunday's) So I will have time to explore all of the above.