Flaps for Velocity?

[gupri]

This is just a thought, which should work.

 

I realise, that the Velocity has currently NO flaps.

 

BUT - if the canards had control surfaces linked proportionately to flaps, this should increase climb, decrease stall speed and therefore shorten roll-out.

 

This system is used (in a much more complicated way) on the Swedish SAAB JAS-39 Gripen fighter and allows exceptional climb, whilst the aircraft is at a horizontal flying position, which allows a better view at the same time.

 

The whole system could be as simple as being worked with a single lever, working with push-pull rods. This should be a relatively easy modification.

 

What are your thoughts on this?

[Jon Matcho]

Research the story of the Beech Starship for how Burt was required to install flaps, which he strongly opposed. You could do it, but it's no simple feat. The issue is that flaps would cause the nose to pitch down, and at that moment (pun intended) you would need more lift from the canard. Personally, I don't see how it's worth the engineering at all, but am not arguing that the engineering COULD be done.

 

Get ready for Marc Z. to answer this question. You'll wish you didn't wake up today.

[Nathan Gifford]

It also complicates construction quite a bit. The other problem is that you will need higher nose position. Not a problem for a tractor aircraft since the prop is in the front. On pushers the prop is moved closer to the runway...not what you would want.

 

Another thing that will shorten takeoff roll is a constant speed propellor.

[rpellicciotti]

It also complicates construction quite a bit. The other problem is that you will need higher nose position. Not a problem for a tractor aircraft since the prop is in the front. On pushers the prop is moved closer to the runway...not what you would want.

 

Another thing that will shorten takeoff roll is a constant speed propellor.

Nathan, you are on to the key thing here. If shorter take-off and landing are required, a constant speed prop is the best way to get it. Take off distances will be considerably less and the drag of the prop in flat pitch will allow steep approaches and shorter roll out after touch down.

 

The main thing is that the constant speed props add about 45 pounds to the aft end of the airplane. This is a problem for the Long-EZ and perhaps the Cozy. The subject airplane, Velocity, is designed to accomodate the constant speed prop.

 

For proof that flaps do not lower the landing speed of a typical canard airplane, the above mentioned Starship had virtually the same stall speed with flaps up or down. Why? Because the reserve lift available from the canard is used up compensating for the pitch down force from the flaps on the main wing. There is little lift left over for actually flying at a slower speed (amateur aerodynamic theory here).

 

This is not to say that a airplane with a canard cannot be STOL, look at the Grizzly. I am just agreeing that for the Vari/Long/Cozy/Velocity/Starship configuration of canard aircraft, flaps don't help.

[bferrell]

The other thing you can do is add vortex generators on both wings to get the T/O and landing speeds down. I intend to do this, though it's not nearly as pronounced a change as using a CS prop.

 

Brett

[gupri]

Thank you all for your replies. My main reason for throwing this idea of flaps, LINKED TO CONTROL SURFACES ON THE CANARD, was the very much improved climb. Marc Z. apparently realised that, by not replying.

 

The shorter field performance would only be an added bonus, but only useful in an emergency landing, which hopefully NEVER becomes necessary anyway.

[Nathan Gifford]

...very much improved climb. Marc Z. apparently realised that, by not replying...

Possibly, but it is just as likely that he either did not see these posts or wasn't interested in replying on this subject again. Silence in plane building should not be confused with concurrance.

 

Climb performance on Velos and Cozys is pretty darn good as is. A number of flyers I have talked to do not go for all the climb performance their ships can deliver since they get a pretty brisk ascent anyway. They opt for being able to look over the nose. On descents, belly board out and both rudders deployed allows a lot of altitude loss.

 

I realize that what you are attempting to do is get a better rate of climb without having a nose high atttitude. Those kinds of control changes to Velos or anything else, do not come free. The added weight, complexity, and build time may not be worth it on a Velo or Cozy. On a different plane, maybe???

[Marc Zeitlin]

Thank you all for your replies. My main reason for throwing this idea of flaps, LINKED TO CONTROL SURFACES ON THE CANARD, was the very much improved climb. Marc Z. apparently realised that, by not replying.

Maybe you could list a few planes that recommend flap usage during climb to improve performance. Not soft/short field takeoff, but climb, as you proposed. Then maybe you could explain how you think flaps would work to do this.

 

Don't ever assume that because someone (anyone) doesn't respond to whatever you (or anyone else) say, that they therefore agree with you. The reasons for silence are manifold. In this case, I was at a John Prine concert Friday night, and then at Copperstate since yesterday morning.

[iwantmycfi]

Just thinking out loud, but a buddy mentioned that the Boeing 737 almost maintains center of lift on the main wings by having fowler flaps and the forward slats. The end result being lift stays near the middle of the wing.

 

Although this would be way to complicated in terms of return (I think), would this be a way to maintain the center of lift on the main wing of a Velocity and not stall the Canard?

 

Tim

[Nathan Gifford]

...Although this would be way to complicated in terms of return...

Don't forget the weight too. Keeping the weight down might give you better performance than adding high lift devices.