Short field performance modifications

[Steve Innova]

Alright-I haven't even begun construction or bought the plans yet, but I confess, I'm hooked. I've already got some ideas about how to modify this thing and wanted to bounce them around:

 

1.) I'm planning on a "short field" Cozy IV. I want to install "aerodynamic flow fences" on the wing trailing edges. I'm hoping that it will lower the landing speed / stall speed by 5-7 kts. Here's the link, has anyone else tried this with any success?

 

http://www.lightspeedengineering.com/KlausInfo/Flowfence.htm

 

2.) Retractable Main Gear: I want to use the retractable landing gear, since that will put the gear out on the strakes and out of line of the prop, preventing debris from being kicked up into the prob on landing/takeoff.

 

3.) Nose Gear Mods: I'm thinking about installing a "mud flap" directly behind the nose gear. This would either by a convential mud flap or a metel wire "basket" to prevent the nose gear from kicking up debris back into the prop. I've never seen this on any US aircraft, but I'm a military analyst, and I know the Soviets installed these on all their Migs and SUs, so that they could operate them from unimproved airfields as neccessary.

 

4.) Laser rangefinder in the nose, for terrain distance on landing. With a nose up attitude, it would be nice to see precise altitude on the panel.

 

Please let me know what you all think of these ideas, obviously I'll have plenty of time to refine them over the next couple years.

 

Stephen

[Marc Zeitlin]

Originally posted by Steve_Innova

1.) I'm planning on a "short field" Cozy IV. I want to install "aerodynamic flow fences" on the wing trailing edges. I'm hoping that it will lower the landing speed / stall speed by 5-7 kts. Here's the link, has anyone else tried this with any success?

Klaus's fences work well on V.E.'s, but apparently have almost no effect on the L.E.'s that they've been tried on. Since a COZY is substantially more similar to a L.E. than it is to a V.E. (aerodynamically), the assumption is that these fences will have almost no effect on a COZY as well.

 

Originally posted by Steve_Innova

2.) Retractable Main Gear: I want to use the retractable landing gear, since that will put the gear out on the strakes and out of line of the prop, preventing debris from being kicked up into the prob on landing/takeoff.

 

There may be good reasons to install retracts, but FOD of the prop isn't one of them. The stock main gear are already well outside of the prop arc, and it's the nose gear that kicks crap up, not the mains, especially if you've got wheel pants.

 

Originally posted by Steve_Innova

3.) Nose Gear Mods: I'm thinking about installing a "mud flap" directly behind the nose gear.

There are a few V.E.'s and L.E.'s that have this - I don't know that I've ever seen it on a COZY, but there's certainly no reason not to do it. Many people taxi with the landing brake down to prevent nose gear crap kick-up damage to the prop.

 

Originally posted by Steve_Innova

4.) Laser rangefinder in the nose, for terrain distance on landing. With a nose up attitude, it would be nice to see precise altitude on the panel.

Ummm, this is WAY overkill. Visibility in a COZY is great, and even on landing, you can see the ground just fine. If you can land a C-172 with the nose up, you can land a COZY with the nose up.

 

The biggest issue you're going to have with a "short field" (and you haven't defined what you think is short) COZY is takeoff, not landing.

 

P.S. - with respect to your other question regarding finding COZY builders in your area, click on the link below, check out the mailing list link, and join the COZY mailing list.

[Steve Innova]

Thanks for the feedback. These are just a few ideas that I had in my spare time. That's too bad that the flow gates don't have any effect on the cozy. I'd love to take a couple good aerodynamics courses while I'm building this, to better understand everything that's going on with the aircraft.

 

Once I start building though, I'll probably have a bunch of new ideas that I'll want people to debunk or verify.

 

Steve

[John Slade]

The biggest issue you're going to have with a "short field" (and you haven't defined what you think is short) COZY is takeoff, not landing.

I'm not sure, but Marc might have meant that the other way around.

 

You can shorten the take off distance by adding more horses, but this wont help with the landing.

 

In general terms the Cozy is NOT a STOL vehicle and can't easily be made into one. I'd suggest that you're heading in the wrong direction if you want to operate out of a field that's less than 3000ft.

[chuckthedog]

First off I understand an empty Cozy weighs as much as a full Long-EZ. I have taken off and also landed in 1500 feet with a 170 lb passanger, Light head wind (5 mph), and 12 gallons of gas. Steep approaches. Hard surface. I have done it. I don't like it, and would not make a practice of it. Too hard on the PIC,brakes,sphyncter. I'm just saying it can be done. I use to live at D-15 Lake Isabella Airpark. Look it up and you will see where I built and learned to fly my Long in and out of. Where I live now the runway is 4000 feet and standard approach. I need no braking for landing or rollout. Life is good.

[Jim Sower]

Originally posted by Steve_Innova

...a "short field" Cozy IV ... "aerodynamic flow fences" on the wing trailing edges ... will lower the landing speed / stall speed by 5-7 kts ...>

How short is short? 3000' is pretty much the lower limit if you live at low DA. If you're even thinking about grass strips, you're looking at the WRONG AIRPLANE.

TE flow fences will help roll authority some, but not landing speed. Vortex generators (VGs)on the main wing and canard will help with TO and land speeds - on my Velocity (aerodynamically much closer to the Cozy than Cozy is to Vari_EZ) VGs reduced landing speed 7-10 kts. I would expect at least 5 kts on a Cozy, perhaps the 7-10 I got.

Depending on how stout an engine you have, landing might be more challenging than TO. Around that, I used to have a lot of trouble slowing down my Long-EZ - it wouldn't slow down enough in the groove to land - it floated in ground effect for 500-1000'. I took to shutting it down coming over the fence. It touched down nicely and reliably right on the numbers and would easily make the first turn off (<2000'). I would re-light it on rollout and continue the march. I never had a problem at all. Finally found the root cause of the fast glide path and was able to land "unassisted" on the numbers every time. Now I only shut down if there is some indication that stopping the airplane might be challenging (hard or agressive stop can cause brake fade, hot brakes or excessive wear). Turning off the motor is easily the most effective short field landing technique available to us (absent hook or thrust reverseal).

 

<... Retractable Main Gear ... put the gear out on the strakes and out of line of the prop ...>

There's a number of reasons for going for retracts. None of them involve FOD.

 

<... "mud flap" directly behind the nose gear ... convential mud flap or a metel wire "basket" to prevent the nose gear from kicking up debris back into the prop ...>

Best way to prevent FOD is a) leave the landing brake down for ALL ground ops, and perhaps don't raise it for the first 20 kts on TO; b) get a treadless (like slick) nose wheel. There's a credible body of thought that the tread kicks up more stuff than the slick tire. Mainly, you'd be amazed how beat up and dinged my belly board gets. To me, that spells e-f-f-e-c-t-i-v-e F-O-D d-e-f-l-e-c-t-o-r

 

<... Laser rangefinder ...>

Is a monumental exercise is PVORT