a 250 Knot Long EZ

[airwrench]

Yes, hanging in the breeze at 250kt plus is what we are looking to approach here. The thin wings will help, maybe a swept (mildly) canard? Or, one which mechanically sweeps forward and back?

[Lifessamsara]

Could someone explain the design concept of the swing-wing canard on the Beech Starship? Apart from being speed related, what was the primary relationship with the aerodynamic function of the canard?

A link to a suitable site that explains this would also be of benefit thanks.

[Jon Matcho]

Could someone explain the design concept of the swing-wing canard on the Beech Starship? Apart from being speed related, what was the primary relationship with the aerodynamic function of the canard?

I *think* it sweeps forward during take offs and landings to achieve a lower stall speed. It sweeps back for higher speeds in flight.

 

A link to a suitable site that explains this would also be of benefit thanks.

www.google.com

 

OR... visit www.uspto.gov and locate Burt Rutan's patent on this particular design. There should be drawings and a complete explanation there.

[Marc Zeitlin]

Could someone explain the design concept of the swing-wing canard on the Beech Starship?

I'll bet someone could.

Apart from being speed related, what was the primary relationship with the aerodynamic function of the canard?

 

To meet the FAR landing speed requirements, the Starship required flaps on the main wing. Flaps substantially change the moment coefficient of the wing, and to counteract the extra nose down moment of the main wing, the canard needed to be further forward. The swinging forward of the canard was coupled to the flaps on the main wing - when the flaps were deployed, the canard swung forward, moving the center of lift of the canard forward. This kept the lift/moment balance of the aircraft correct.

 

It's not "speed" related - it's flaps related. Now, you only deploy flaps at relatively low speed, but no matter what the speed, if the flaps weren't deployed, the canard doesn't move.

 

The mechanism is extremely complex.

 

The patent # is 4,641,800.

 

Interestingly enough, while poking through the patents, a derivative patent for a SLIDING canard is presented by a "John A. Lockheed", in 1989, that uses a COZY III as the basis for the figures. The figures are reasonably explicit as to the workings. Whether this aircraft was ever built, I have no clue - I've never heard of it or seen it. The patent # is 4,848,700.

[Lifessamsara]

Well Marc, thanks for that, it certainly made interesting reading (along with some of the other concepts in the Patents in the same area).

It would seem if a canard used a swing canard configuration along with a flap it would provide a suitable TO/landing performance, and provide a lesser drag profile for for higher speed cruise (less drag as Carolina pointed out).

I wonder, does this seem to be indicating the 250kt OpenEz design brief?

What kind of flap design could be used on an OpenEz plan?

Im enjoying the open thinking in this thread so far, and hope it continues.

 

Cheers,

 

Bruce.

[Marc Zeitlin]

It would seem if a canard used a swing canard configuration along with a flap it would provide a suitable TO/landing performance,

Since canards already have "suitable" TO/Landing performance, the addition in weight and complexity of moving the whole canard airfoil is completely unwarranted. It's on thing to take on the complexity in a 6-8 seat bizjet - it's quite another in a 4 seat (or 2 seat) GA aircraft. It's why you don't see multi-surface fowler flaps on GA aircraft, either.

 

and provide a lesser drag profile for for higher speed cruise (less drag as Carolina pointed out).

If there were any truth to Karolina's statements about drag, then it might be worth thinking about. However, her suppositions about drag and airfoil shapes, with respect to L.E.'s and COZY's are incorrect. Witness the many canard aircraft (Berkut, supercharged E-Racer, souped up V.E.) that can fly well into the high 200 - 275 Kt. range with the stock airfoils. It's not the thickness of the airfoils that's creating any issues here.

 

I wonder, does this seem to be indicating the 250kt OpenEz design brief?

What kind of flap design could be used on an OpenEz plan?

I'm not sure what your first sentence means. Personally, I wouldn't even think of adding flaps, and the concomitant complexity of canard rotation/sliding to my aircraft - the reduction in reliability alone would make it a non-starter. I can land and stop in less than 2000 ft, normally - 3000 when at gross weight and forward CG. There are almost no airports that I want to go to that I can't get in and out of.

 

If I wanted to go faster, I'd concentrate on intersection drag of the gear, cooling drag, and I'd turbocharge my engine. Leave the airfoils out of it.

[Jon Matcho]

If there were any truth to Karolina's statements about drag, then it might be worth thinking about. However, her suppositions about drag and airfoil shapes, with respect to L.E.'s and COZY's are incorrect.

Karollina has a valid point: airfoils CAN be replaced to achieve less drag. Klaus Savier apparently believes this to be the case (I'm sure he's not doing it for 'looks').

 

Witness the many canard aircraft (Berkut, supercharged E-Racer, souped up V.E.) that can fly well into the high 200 - 275 Kt. range with the stock airfoils. It's not the thickness of the airfoils that's creating any issues here.

I'm not familiar with the "souped up V.E.", but the others performers you mention (those that can get 250kts?) are powered with Lycoming 540s. Your point is valid of course -- a carbon-skinned Berkut will indeed go fast.

 

If I wanted to go faster, I'd concentrate on intersection drag of the gear, cooling drag, and I'd turbocharge my engine. Leave the airfoils out of it.

What else? How about the intersection of the strakes to the fuselage (upper and lower)? Can that be improved? What about the winglet-wing intersection the Cozy Girrrls did (check out 'Current Status' on their Web page)?

[Marc Zeitlin]

Karollina has a valid point: airfoils CAN be replaced to achieve less drag. Klaus Savier apparently believes this to be the case (I'm sure he's not doing it for 'looks').

Klaus is trying to get the last few knots out of an airplane that has already had everything even remotely easy done to it (assuming he's doing to the L.E. what he's already done to his V.E.). Karollina's point about canard thickness being a substantial portion of the drag of the aircraft is just wrong. Go look at drag polars of various airfoils appropriate for canards, find the minimum Cd, and then think about how many pounds of drag dropping that Cd will eliminate. Then consider that a reason to change the airfoil of the canard would be to eliminate the propensity for Mach Tuck at the high speeds that Klaus is trying to achieve.

 

There may very well be airfoils out there that would have better Cd's at the Cl's used for the canard, but the thickness is not the major issue. That's what I was directing my comments to, along with the comment that fuselage lift could replace wing lift. Since wings are far more efficient (Cl/Cd) lifting surfaces than fuselages, that's the last thing you'd want to do. Plus, thin airfoils have terrible stall characteristics - not optimal for a canard aircraft.

 

Take a look at:

 

http://www.mh-aerotools.de/company/paper_3/yaka.html

 

You can see that the minimum Cd for all the airfoils listed (with smooth surfaces) is about 0.005, in the range of Cl's we're talking about. You're not going to substantially reduce that (at low Cl's) by changing airfoils. A look at Appendix IV of "Theory of Wing Sections" shows that almost all minimum Cd's are in the range of 0.004 to 0.006, with the lower "drag buckets" coming only in a very small range of Cl's (with thin sections). You might change OTHER characteristics by going to a thinner airfoil, but not the minimum drag coefficient, at least not substantially. This implies that changing canard airfoils will not have a large effect on top speed (from a drag standpoint).

 

I'm not familiar with the "souped up V.E.", but the others performers you mention (those that can get 250kts?) are powered with Lycoming 540s. Your point is valid of course -- a carbon-skinned Berkut will indeed go fast.

I was referring to Klaus's aircraft. His O-200 puts out substantially more than 100 HP.

 

What else? How about the intersection of the strakes to the fuselage (upper and lower)? Can that be improved? What about the winglet-wing intersection the Cozy Girrrls did (check out 'Current Status' on their Web page)?

Everything can be improved. The things I listed are the main ones, and will get you many knots relatively simply. The things you list are second order effects - optimizing them MIGHT get you a few knots, but it's hard to say.

[Jon Matcho]

Then consider that a reason to change the airfoil of the canard would be to eliminate the propensity for Mach Tuck at the high speeds that Klaus is trying to achieve.

That's a joke right? I hope so... because I think I just got it!

 

That's what I was directing my comments to, along with the comment that fuselage lift could replace wing lift. Since wings are far more efficient (Cl/Cd) lifting surfaces than fuselages, that's the last thing you'd want to do.

I agree, for other reasons, namely the complexity as indicated by the reference material you're citing.

 

Still, what about a more spherical nose shape that's better blended into the body from the canard forward? Everyone wants to put on supersonic nose cones, but the perfect subsonic shape is a rain drop (cone w/sphere at end). I've been thinking about designing this new use using CAD, and taking cross sections for the bulkheads needed to form the "improved" shape. What do you think, worthwhile? 10 knots or 0.1kts?

[Marc Zeitlin]

That's a joke right? I hope so... because I think I just got it!

Well, you'll have to explain it to me, because I'm not sure what you "got" - there was no joke....

 

Still, what about a more spherical nose shape that's better blended into the body from the canard forward?.... What do you think, worthwhile? 10 knots or 0.1kts?

A lot closer to the latter than the former. It's not like folks with the long nose L.E.'s are seeing any speed decreases.....

[Jon Matcho]

Well, you'll have to explain it to me, because I'm not sure what you "got" - there was no joke....

I thought 'mach tuck' was a phenomena that occurred as an aircraft approached the speed of sound (~mach 0.85?). If that's the case, I don't understand how 'mach tuck' is anything anyone in a canard will have to worry about. Then again, I suppose the jets and rockets could get that fast if they tried.

 

What am I missing? What's 'mach tuck' have to do with Klaus?

[Marc Zeitlin]

I thought 'mach tuck' was a phenomena that occurred as an aircraft approached the speed of sound (~mach 0.85?). If that's the case, I don't understand how 'mach tuck' is anything anyone in a canard will have to worry about. Then again, I suppose the jets and rockets could get that fast if they tried.

 

What am I missing? What's 'mach tuck' have to do with Klaus?

You must have missed the multitudinous discussions of Mach Tuck on both the mailing list(s) and the fora. The Roncz canard is theorized to have a critical Mach # of about 0.55 - 0.75. At high altitudes, with a turbocharged engine, canards can approach that. That was my reference - to go a LOT faster in one of our aircraft, the canard airfoil would have to be changed in order to avoid this phenomena.

 

Read the thread:

 

http://canardaviationforum.dmt.net/showthread.php?t=2085

 

Especially Richard Riley's last sentence in his last post.

[Jon Matcho]

You must have missed the multitudinous discussions of Mach Tuck on both the mailing list(s) and the fora.

I do recall the discussions, and a visit to the link you provided reminded me of what I thought then -- that the issue is likely (and hopefully) going to have nothing to do with my airplane.

 

Thanks for the education Marc.

[7480W]

Has anyone considered the possiablity of sweeping the main wings more to reduce drag. I know that with this the twist would have to be increased in order to not stall tips first. Maybe im being crazy here. One possibality with too much money and time the possibality of movable wings, so it could remain the same landing and low speed flight. If the wings were swept back far enough it could almost be a delta style wing. I know some very different principials, but it could help with the mach number problem, I was told that a greater swept wing with the same airfoil has a higher mach # usage, Though not from the most relaible sorce.I think that the cannard would have to be different as well to stop it from being the limiting factor. I think this will get really complex really quickly but, Just a thought. Thank You all for being so helpful as well all the great advice in this thread.

[AP3_C]

"Mach Tuck"

 

From the little info I have I understand that the occurance of Mach Tuck is given to the situation where the Centre of Pressure transfers from the (approx) forward third of the wing section in normal flight to the rear third (approx) of the wing section as the aerofoil approches and passes through the speed of sound thus causing the aircraft to pitch down.

 

Others out there may have a better explination but I cannot see how aircraft like the LE and a like would suffer from a situation like this as the speeds required to fly at would be well exilerating to say the least.

 

Jamie

[AP3_C]

Did a bit more reading and I can see how maybe the LE type aircraft can have critical Mach number issues.

 

Critical Mach number - speed at which the aircraft is flying to have air flow on airfoil accelerated to the speed of sound. Thus possible Mach Tuck issues.

 

Jamie

[Lifessamsara]

Well guys, I am gladly receiving quite an education through this thread, so thankyou.

Marc, I can see that the current airfoil for the main wing may be suitable for a cruise speed of 250kts (as that was the original concept of this thread), and that you are indicating addressing the the design of the fuselarge to reduce drag may be the best way to produce an economical high speed cruise.

Id be interested to know what your thoughts are about improved performance of the nose, canopy and width/height of the fuselarge are Marc. I for one do not need to widen a cockpit 2-4" just yet (that middle age spread has not kicked in just yet )

Im also interested in the discussion on the vortex generation drag performance associated with our winglet wings. Is there a way to also reduce drag here?

Let's not forget what Mike Arnold achieved with with just 65hp.... 213mph. Some guys have been dropping 220hp in the back of their canards....... why cant a 300kt top speed and 250kt possible with a basically slippery design and all that power be achieved?

Keep up the open and creative thinking guys, and the technical discussion of the realitive merits of each idea (and leverage off that thinking).

I look forward to the future posts.

 

Cheers,

 

Bruce.

[karoliina]

shapes, with respect to L.E.'s and COZY's are incorrect. Witness the many canard aircraft (Berkut, supercharged E-Racer, souped up V.E.) that can fly well into the high 200 - 275 Kt. range with the stock airfoils. It's not the thickness of the airfoils that's creating any issues here.

 

I made that assumption based on the fact that Greg Richter does not

go faster than 200-240 kt with his Cozy-Jet according to the article. That is not very much considering that there is a lot of more power available in the jet engine than there is in a piston engine (no matter what horse power) at the same altitude. I may be also incorrect with the assumption, but to me it sounded like the drag starts to rise exponentially above the normal speed range of the canards because the airfoils are not designed for a such speed range. As a matter of fact on the other hand, I am not aware to which speed range the airfoils of Cozy are designed to and would appreciate if somebody with more knowledge would enlighten me.

 

Best Wishes,

Karoliina

[Marc Zeitlin]

I made that assumption based on the fact that Greg Richter does not go faster than 200-240 kt with his Cozy-Jet according to the article.

"Does Not" and "Can Not" are two different things. Greg has explicitly said that his aircraft COULD go a LOT faster, but he limits the speed because the Vne of the COZY is 220 mph IAS, so he doesn't go faster than that.

 

... I may be also incorrect with the assumption, but to me it sounded like the drag starts to rise exponentially above the normal speed range of the canards because the airfoils are not designed for a such speed range.

And yet Jack Morrison's E-Racer has gone ~300 mph, as have some Berkuts, and Klaus's V.E. is in the 250 mph range. Drag does rise, and the aircraft are not designed for those speeds, but they can achieve them with a lot of power and judicious drag reduction. Greg's jet could EASILY beat those #'s, if he was willing to exceed Vne.

 

As a matter of fact on the other hand, I am not aware to which speed range the airfoils of Cozy are designed to and would appreciate if somebody with more knowledge would enlighten me.

As Richard Riley has pointed out, the Critical Mach # of the canard is somewhere between .55 and .75, and the main wing may not be far different. This gives an upper limit for TAS. Without the drag polars, we can estimate a Cd of 0.005 for each wing at low AOA's and get an approximate speed/power curve. It's pretty obvious (since it's been done) that 300 mph is achievable with enough power, and "enough" is defines as somewhere in the 300 HP range.

 

Let's not forget what Mike Arnold achieved with with just 65hp.... 213mph.

Let's not forget that that's a tiny 1 seater. A very efficient one, no doubt, but tiny.

 

Some guys have been dropping 220hp in the back of their canards....... why cant a 300kt top speed and 250kt possible with a basically slippery design and all that power be achieved?

It IS possible, and it's been done. I've said so many times, and others have proved it. The question is not CAN it be done, but how close to the edge are we when doing it?

[Len Evansic]

I can't speak for Greg, but he has indicated to me that the CozyJet is a bit of an R&D mule. He's still tinkering with it, and still expanding the envelope. The CozyJet is itself not an end, but a beginning of his next project where he wants to tackle the Vne issues with stiffer wing structure and some other changes. As much as he is experimenting with the design, he is trying to do so in a cautious manner.

 

-- Len

[Jack Morrison]

Mark is exactly correct on this issue. I have been there and let me tell you 300 mph is extremely fast for these canard AC. No one really knows where that edge is, and I would be verly reluctant to push past what has already been accomplished . If mach tuck occured at these speeds, there is no recovery and your last ride would wind up being a slow ride in a hearse. I am not a young person in age, but I plan to be around for quite a while

 

Jack Morrison

[longez360]

That is one heck of a nice E-Racer you have Jack. I managed to battle though a crowd and see it at OSH. What sort of performance (TAS) are you seeing at altitude?

 

Cheers,

 

Wayne Blackler

IO-360 Long EZ VH-WEZ

Melbourne, AUSTRALIA

[Jack Morrison]

Wayne

Last year I saw 253kt T . at 10,000 2980 rpm- 43in MP . That was turning a catto 3 blade 66/103. Im sure there was more left but I have been fighting cht gremlins for 5 years on this AC and I could not hold any HP down for over a minute or two. Estimated 360 hp is not easy to cool. I have changed my cooling system 6 times in the last 5 years and have tried about every alteration possible to improve each system with only limited success. That is until today about 41/2 hours ago. With the new(7) designed plenums I got the near perfect differental numbers I was looking for and the cooling was great. I still have not tested my new prop, a catto 64/113. I will post the results in the next few months. I am going to disassemble the Ac this weekend and strip all the paint off and do a repaint, (same colours)I should loose about 100+ lbs. Lousy job but I will enter the cup race this year and need to loose some weight. If all works out as planned, I should do well in the race, only problem I have to run in unlimited. By the way, that longEZ of your 's is georgous. You have done a great job on your EZ. Good luck down under.

 

Jack

[Jon Matcho]

Jack... it's great to hear you've got your cooling working. That had to be driving you nearly insane.

 

I'll be looking forward to seeing some pics, or looking things over in the future.

[Jack Morrison]

Thanks Jon

I guess persistance and dedication do rule. One of these days soon, when I finally get back together, I'll take you for a ride, its impressive. I'll send some photos of the new cowlings when the painting is completed. They netted me + 8 kts.

 

Jack