Tailwind questions from a real newbe

Dan,

Welcome!  I am no expert on the Wittman Tailwind, but from the gist of your questions above (#2, #5 and #7) it sounds like what you really want is a smaller, lighter design like the Tailwind but more suitable for short field operation.  That does exist in the "reverse-engineered" Wittman Buttercup.  The current version is set up for a 100hp Continental O-200 but the original flew quite well on a C-85, so an 80hp Rotax 912 might well work just fine.

Cheers,

Matthew

Thanks Matthew,

You are right, but... I actually want all the top end speed of the tailwind with the shortfield performance of the Buttercup. My thoughts are that with technolgy that did not exist when the Tailwind and Buttercup were designed (e.g. vortex generators, composits) one could get short field performance from the tailwind without sacrafing much performance. For example, I have seen specfications that the takeoff ground roll of the W10 is less than 800 ft. That's pretty short to begin with given a cessna 152 needs 950+ and they can be given STOL capability to take off in less than 300.

I like the 912 because the cost, horsepower to weight ratio seems good. There is a 100hp 912 too.

Hi Dan,

I am on my second Tailwind, doing a ground up restoration of a 1958 W-8.  My first was a W10.  Both of my planes had/will have metal wings, so I will try and answer your questions.  Check out groups.yahoo.com/group/Tailwindforum for a wealth of info.

1.  I am building metal wings for my W-8.  The W-10 and W-8 have the same wings, by the way.  Consult the group for all differences between the 8 and the 10.  There are a few, but basically they are the same plane.  Callbie Wood sells metal wing plans for $75 or so.  There are many drawing discrepancies between the old Wittman plans and the new Spruce plans.  They are all spelled out in the group and also Jim Stanton has a construction manual he put together.  It would be well worth the money to get.  Also, if you want Jim Clements mods, they are also available.  They are the ones that make the Tailwinds look like all the recent award winners do.  Also well worth the money.  My first Tailwind had a Riblett airfoil and 2 feet more wingspan.  My climb was 2300-2400 FPM and it got off the ground quickly with 150hp.  My W-8 (avatar) will have the Wittman airfoil and span as in plans with 100 hp.

2.  Vortex generators would work just as on other planes.  if anything it will help the initial slight "float" one feels right when a Tailwind takes off.  A short field airplane a Tailwind is not overly suited for.  Unimproved fields, definitely yes.  Tailwinds are well known for their gentle stall characteristics. 

3.  Larger windows have been on several Tailwinds.  Skip Stewart's W-10 (the airshow pilot) had doors that were mostly window.  Jim Clement's mods provide for larger doors, among other things.

4.  Folding wings could easily be adapted to a Tailwind.  A lot of Nesmith Cougars have folding wings.  That would be, in my biased opinion, the only thing I would borrow from Cougar plans.  Most of the very nice Cougars have a lot of Tailwind in them.  The Tailwind is just a much better airplane.

5.  Nobody I know of has tried the Rotax.  It might work in a W-8 airframe.  A W-8 is essentially 6-7 inches shorter due to the larger tail surfaces required for the larger engines on the W-10.  The plans show both.  The best engine for the W-8 is the O-200 and the O-320 for the W-10.  There is a recent one flying with a Mazda and a few have flown with Olds/Buicks.  Only one owner I know of has been satisfied with this set-up.  My O-200 freshly overhauled was $7500.  The O-200 W-8 and the O-320 W-10 get roughly the same economy (a little over 30MPG) at the same speed and this has been proven time and again.

6.  Check the safety record on the NTSB.  About 2 1/4 pages from the beginning.   Ground handling is essentially the same as a Citabria.  Landing speed is about 5-10mph higher than a Citabria.  A Citabria is an excellent transition airplane. 

7.  Big wing extensions over 4 ft should not be done due to the requirment of the wing geometry.  If you want to redesign and test the wing go for it.  My 26' wing span dramatically inmproved climb performance.  Ground roll of 500 ft on pavement is possible with the Riblett airfoil, 26-7 ft of wingspan and probably an O-360 and VG's.  Jim Clement's latest has an O-360.  10 pounds heavier and about $4000 more for the core with increased fuel burn if you open the throttle.

There just isn't anything better than a Wittman Tailwind.  They are relatively easy to construct and it is definitely an inexpensive flyer for it's class.  Hope this helps and good luck,

Jerry

N6053V

Jerry, thanks,

Great information. I may build from scratch but I also may do what you are doing and that is refurbishing an existing airframe. A 500 ft ground roll is great. I hope to go in and out of unimproved fields (as opposed to landing on a river bank, not looking for a super cub). The one great attractions of this aircraft is the broad performance envelope. Also, I did not realize the 0-200 was as light as it is, that's what I liked about the Rotax was the power to weight ratio. Thanks again for the great answer.

Dan,

Keep in mind the 500 ft was an estimentation...that would be a paved runway keeping a light W-10 with at least 160 hp and a constant speed prop.  That means, minimal basic instruments only-no IFR instrumentation and no lighting with as light of an electrical system as possible.  I plan on an O-200, no electrical, basic instruments, and doing things as light as possible.  The only CS prop I know of right now is Jim Rust's W-10 with his company prop.  He is located at Gillespie Field in El Cajon, CA.  His takeoffs are something to see.   He would be a great resource for takeoff performance with a Tailwind. 

With that, a Tailwind is not a short field airplane and you will probably be disappointed.  It was not designed for this mission.  What a Tailwind is is an extremely efficient, economical, cross country speedster.  Fly it like your Cessna, Piper, Mooney, etc and you will be impressed and never want to go back to any "do all" airplane.    It is at home on a grass as well as paved runway-very rugged and tough. 

If short field is what you need, then the Buttercup is the way to go, esp. with around 100hp.  Also, you will like the increased cabin room because it is larger, since you were describing larger doors and windows.  One of Steve's design parameters of the Buttercup was the fact that his Grandmother was getting up in age and liked to fly with him, so he made it easy to get in and out of.  The Tailwind was designed as a better plane to keep parts coming to his racers faster, what the Buttercup originally did.  The Tailwind uses many different design philosophies, but is essentially a highly refined Buttercup.  When Steve passed, he was working on adapting Buttercup leading edge flaps to a Tailwind.  So far, I know of nobody who has done this. 

With that, you may be able to do a W-8 with a Rotax adapting the leading edge flaps to the Tailwind and have the performance you need-it would be interesting, to say the least.  You would need the Buttercup (for the LEF design) and Tailwind plans for the rest.  Keep it light and minmal ;) 

Jerry

N6053V

Dan,

I think you need to analyze the airplane's mission - in other words, what you are going to primarily use the airplane for?  Are you planning to stop using commercial airlines and take long cross-countries in your new plane?  Or do you mostly plan to land at every airport in your state and enjoy hanger chat at breakfasts?  There is no sense in building an airplane to satisfy a perceived need that ultimately you will only enjoy 5% of the time.

Reading between the lines in your initial post, it seems to me that the Buttercup is much closer to your mission than the Tailwind.  You can take off and land on a dime (so to speak) while still cruising much faster than the typical Cherokee or 172.  The buzzy little Rotax will do just fine or you can go conservative and relaxed with an O-200 or O-235.

You will have much more fun in an airplane that satisfies 95% of the equation rather than 5%.

I've attended two lectures on the subject of "mission" and learned a lot about refining my future airplane building focus from Martin Hollman (Super Stallion) and Earl Luce (Buttercup/Tailwind).

Yours,

Chris Koch

Buffalo, NY

You guys right about mission so I'll explain what I expect.

First, I used to commute from suburban southwest Philadelphia to WhitePlains, NY, a 138 mile 3 hour drive over the GW bridge (a commute from hell) about twice a week. It seems that I may get a contract from another company there and would need to go up there weekly. So,  I plan to fly from local airports here to West Chester county airport in White Plains once a week.

About once every other month I plan to fly from Philly to Chicago, specifically Schaumburg or Palatine. A mix of business and family.  That is about a 650 mile cross country.

Finally, I want to fly my son (age 12) to every local airshow, airport with a restraunt, as well as to maine and canada camping and fishing. He loves airplanes and got me to get my license in the first place. So as you can see the short field unimproved field stuff is secondary. (Has anyone ever put floats on a tailwind or buttercup!)

It's my impression that the buttercup is quite a bit slower than the tailwind. Also, much of the improvements i read about coming from Clement, Callbie, etc. are not applicable to the Buttercup. For example I might be more inclined to put buttercup wings on a w-10 fuselage, but I'm not an engineer and don't know how to do those modifications safely.

The advice you're giving is great, thanks. I've asked for info from Aircraft Spruce, and I emailed Clement to ask him some questions as well so you folks are a great resource in my research.

Talk to Mike in MN (He always signs Mike and Jazz on the Yahoo group).  He is building something like you said-a Buttercup with a Tailwind fuselage.  There is a group for the Buttercup as well, and also talk to Earl Luce-he may be able to help you out in this area.  His number is on the Buttercup website.

As far as the Buttercup being much slower-not quite so.  They still do pretty good.  165mph cruise is what is usually the norm for an O-200 Tailwind-some faster, some slower.  130mph cruise is for the Buttercup with an O-200...and Earl's wife likes the Buttercup way better  

Good luck,

Jerry

N6053V

Jerry, I am looking at building a Buttercup with a riblett airfoil to improve the clean stall speed to meet LSA. I wondered what  airfoil was on your Tailwind and if it improved ( lowered) stall speed.

Jim 

RV6 N47EX

Jerry, I’m going to ditto on Jim’s question as to which Riblett foil you used…

 I follow the chatter on the Buttercup and Tailwind forums and at least one builder is apparently adopting much of the Tailwind for from mid-cabin forward to the Buttercup -- and although the notion of putting “slower” wings on a Tailwind seems to offend some, it seems like a entirely logical solution if one is (say) trying to meet LSA, but retain the Tailwind efficient DNA, if not outright speed…

 Needles to say I’ve pondered similar questions, and am with weeks of beginning a build – I’m just not sure what… The simplicity of the Tailwind (I have the W10 plans) is decidedly friendly and the spar carry-throughs are within an inch (or a slip of the torch, if you will…) of the spar spacing on a PA-15/17 wing, but it would seem to be overkill to saddle Mr. Wittman’s little speedster with a Piper-esque USA35B-mod (I think) foil, and I’ve long been enamored with Harry’s soft-stall and low pitching-moment work…

 What I’ve wondered is turbulent of laminar flow… without getting sidelined into the merits/shortcomings of an LSA-Tailwind, it does seem that if the Tailwind form of construction, whether metal ala Cobie or plywood ala Wittman, was retained then one could go with one of Harry’s 35, 37 or even 40 series laminar foils, or if one was trying to tease out the last ounce of low-speed capability perhaps more Buttercupish, then one of the more aggressively cambered 30 series could work…  well, after all even with Steve’s august imprimatur, it is still an “experimental,” ain’t it…

 Doubtless none would be as fast as Wittman’s highly refined foil, but matching the correct foil to a modification of flight envelope might be interesting and practical – along with doubtlessly deepening the spars (box spars – oops, now were getting more complex..) or whatever if the wing was modestly lengthened…

 Anyway, just wondering what you found worked, and perhaps how well you feel it worked…

Thanks…

-- Larry

Virginia, USA

Hello, I'm a former C170 owner and aTailwind/Buttercup Newbie. I started to gather information about two years ago, before beginning my build (I like to work from plans).

My focus has been to design the cockpit for the aging pilot population, as most LSAs are darn difficult for old guys to get in and out of.  Try for yourself at Airshows where LSA designs are displayed and accessible.

I presented a paper at the Experimental Sailplane Association Western Workshop on this topic in 2009, and I'm now creating a plan set, melding the Tailwind with the desirable features of the Buttercup, into a 3D AutoCAD model.  This design is a continuation of my desire to build an affordable LSA Cruiser that is both fast and slow.

My design will not explore much new teritory, but use proven mods developed over the years by Jim Clement, Calbie Woods and others. AutoCAD 3D  gives me accuracy and a wrap around persepctive.

Contact me if you'd like to hear more.

Thanks

John

Winter Park, FL

Hey guys,

Apologies for the late reply.  The airfoil was the GA37U-A315 recommended by Harry Riblett himself.  It provided for a thicker chord.  I can definitely tell the difference in that area as I am building new wings for my W-8 right now with the Wittman airfoil.  He did say in his correspondence with the builder it would be hard to beat the NACA 4309/0006 (Wittman) for the Tailwind top-speed wise.  As far as climb, all I know is it shot right up into the air and the VSI said 2300 at 100 mph-I am hearing 1500-1800 as the climb on the forum.  I would note the wingspan was 26.5' Vice 24 as well, so that might have helped.  With that, if I wanted climb I would probably go with the Riblett in the same coniguration, but I am looking for speed.  Another way to slow a Tailwind down is to raise the cockpit height, as the Cougar did.  It slows them down by changing the lifting body airfoil of the fuselage.  

 I think the Tailwind is a great airframe-one I would base another design on.  Mostly because there is nothing that comes close to and sometimes even pass up the RV's that I know of...and  I like the high wing for crash survivability and the relative ease of getting in and out.   I am very biased though.  Hope this helps and good luck.

Jerry

N6053V