Cowl Mods

[aviatoreb]

23 minutes ago, mike_elliott said:

Waaay too expensive. Target Chip Ganassi racing spends as much as a new Mooney ultra to build a 1/10 scale model of their cars for wind tunnel testing. Then there is the cost of the wind tunnel. Heck, Chip bought a mountain in PA that a road tunnel was in after a highway was rerouted just so he could plug up one end and make a full scale wind tunnel sort of out of it. Then the stinking sanctioning bodies banned that testing after one of his drivers shot his mouth off about it.

Anyone know how much it costs to buy time in one of those very big wind tunnels that are big enough for a full sized Mooney?

I guess inflight testing and tweaking, taping on yarn, etc is the much more money efficient way to go.

[mike_elliott]

I don't know if Boeing has a wind tunnel one or not. I know Adrian Renard ' s won't hold a Mooney. I have no clue what they cost to use, but do know it is very high. It's not like there is a high demand, or they don't take up space or they don't consume jigawatts, or they are mass produced, or they don't require specialized skill.

[bonal]

Couldn't something like this be done with a computer aerodynamic model

[mike_elliott]

42 minutes ago, bonal said:

Couldn't something like this be done with a computer aerodynamic model

It is, but the reality check in racing is a wind tunnel.

[Hank]

1 hour ago, bonal said:

Couldn't something like this be done with a computer aerodynamic model

Computer numerical analysis first,then models are made and wind tunnel tested. Designs are tweaked in the computer, and retested until achieving satisfactory results. Then full scale testing is done, with hopeful minimal tweaking required. Then you have the final design. This last step happens (for our planes) during the FAA required certification flight tests. Read up in the Honda Jet to get a feel for how this works.

[bonal]

1 hour ago, Hank said:

Computer numerical analysis first,then models are made and wind tunnel tested. Designs are tweaked in the computer, and retested until achieving satisfactory results. Then full scale testing is done, with hopeful minimal tweaking required. Then you have the final design. This last step happens (for our planes) during the FAA required certification flight tests. Read up in the Honda Jet to get a feel for how this works.

I know that's how design and modification is done and I was thinking it could save some time and money if our guys on Mooneyspace looking to make improvements to the original design might use this approach to minimize mistakes or changes that don't improve on what's already been done. I guess what I was thinking is there software that is affordable that can be used on a typical home PC

[MyNameIsNobody]

One "guy" SabreMech is making an "improvement" on the 50 year old design.  Wind tunnel testing?  Funny.  How about take existing improvements and incorporate them with what ends up being an aesthetic and function (speed/reduced temps) result?  Is this a popular mechanics thread?  What has already "been done" is a guppy mouth OEM nightmare.  A simple lower cowl mod, aesthetic fiberglass mods that crack and are not available and an über expensive LoPresti (why/how can you justify on a vintage bird)...and the SabreMech Goldillocks "solution" that if priced right will be JUST RIGHT.

Wind tunnels....

[Yetti]

The origin of the question is can a better insert be made for the guppy mouth?   Apparently the current lower insert by Laser does nothing for speed.  The JPI mod seems to increase speed but is of dubious quality due to the fiberglass parts.   I was thinking an aluminum insert for the lower and upper cowls.  Something that would rivet onto the very wide and rounded surface area that is in place.   The J fiberglass upper cowl seems to have it's own issues.  Why not keep the nice sturdy alum upper cowl and just do some modding.

[MyNameIsNobody]

Because modding the "existing circle/guppy" is not as aesthetically pleasing as riveting in a new upper and lower cowl mod.  The C has that ugly chin and the E has that inefficient ram air...

[takair]

On February 13, 2016 at 11:09 AM, bonal said:

Couldn't something like this be done with a computer aerodynamic model

http://www.aerologic.com/

From Peter Garrison of Flying Magazine fame.  He also has an interesting Blog about the development of his experimental aircraft, Melmoth 2 (Google to find link).  He is constantly working small tweaks to improve speed, cooling and fuel efficiency.  His plane makes our Mooneys seem like gas hogs.  Interestingly he uses an updraft cooling system, which has some of its own challenges, the biggest seems to be that you pick up some exhaust generated heating.  

[carusoam]

Cowl vents out the top...

Standard fuel injected engine layout has our intakes at the top and exhaust running out the bottom.

http://melmoth2.com/texts/Pictures.htm

the M20C has both intake and exhaust on the bottom...

Interesting,

-a-

[takair]

1 hour ago, carusoam said:

Cowl vents out the top...

Standard fuel injected engine layout has our intakes at the top and exhaust running out the bottom.

http://melmoth2.com/texts/Pictures.htm

the M20C has both intake and exhaust on the bottom...

Interesting,

-a-

Also, it is a 4 place!  Interesting feature is that it shares seat backs with fore and aft seats.  Rear seats face aft.  

[Andy95W]

10 hours ago, MyNameIsNobody said:

The C has that ugly chin and the E has that inefficient ram air...

Hey!  Who you callin' ugly?

[Sabremech]

On ‎2‎/‎14‎/‎2016 at 6:46 AM, Yetti said:

The origin of the question is can a better insert be made for the guppy mouth?   Apparently the current lower insert by Laser does nothing for speed.  The JPI mod seems to increase speed but is of dubious quality due to the fiberglass parts.   I was thinking an aluminum insert for the lower and upper cowls.  Something that would rivet onto the very wide and rounded surface area that is in place.   The J fiberglass upper cowl seems to have it's own issues.  Why not keep the nice sturdy alum upper cowl and just do some modding.

Hi Yetti,

 I think the real downfall of just filling in the guppy mouth is where the air inlets end up. They are too close to the base of the cylinder versus closer to the top of the cylinder and the cooling fins where most of the heat is developed. With the ARI enclosure that I had previously, it was not uncommon for me to see cylinder temps of 430-440 on takeoff.

 David

[Marauder]

On ‎2‎/‎14‎/‎2016 at 6:46 AM, Yetti said: The origin of the question is can a better insert be made for the guppy mouth?   Apparently the current lower insert by Laser does nothing for speed.  The JPI mod seems to increase speed but is of dubious quality due to the fiberglass parts.   I was thinking an aluminum insert for the lower and upper cowls.  Something that would rivet onto the very wide and rounded surface area that is in place.   The J fiberglass upper cowl seems to have it's own issues.  Why not keep the nice sturdy alum upper cowl and just do some modding.

Hi Yetti,

 I think the real downfall of just filling in the guppy mouth is where the air inlets end up. They are too close to the base of the cylinder versus closer to the top of the cylinder and the cooling fins where most of the heat is developed. With the ARI enclosure that I had previously, it was not uncommon for me to see cylinder temps of 430-440 on takeoff.

 David

David -- have you starting compiling flight data yet? Curious what the before and after temps look like. As well as the speed gains.

Sent from my iPad using Tapatalk

[Sabremech]

Hi Marauder,

 I've put a couple of flights on it and the cylinder temps are down 30 degrees Fahrenheit. I made an adjustment to my cylinder cooling ring size increasing the diameter from 4.5 inches to 4.7 inches and will fly again as soon as the weather breaks and we start seeing consistent warmer temps. I don't fly much if at all during the Winter as I no longer care to deal with the temps or the struggle to get the airplane in and out of the hangar.

 Thank you,

 David

[mike_elliott]

1 hour ago, Sabremech said:

Hi Marauder,

 I've put a couple of flights on it and the cylinder temps are down 30 degrees Fahrenheit. I made an adjustment to my cylinder cooling ring size increasing the diameter from 4.5 inches to 4.7 inches and will fly again as soon as the weather breaks and we start seeing consistent warmer temps. I don't fly much if at all during the Winter as I no longer care to deal with the temps or the struggle to get the airplane in and out of the hangar.

 Thank you,

 David

Cool (pun) concept, David. Have variable sized inlet ring inserts to "tune" cooling for the specific cowl config ...IE does it have a fixed cowl clap in addition to the cowl flaps? Use the "D" size ring...etc...

[Sabremech]

3 hours ago, daver328 said:

Sissy ... if Aaron Rogers can get out there ... ;-)

He only has one job, I have 3!  

[steingar]

6 hours ago, Sabremech said:

I don't fly much if at all during the Winter as I no longer care to deal with the temps or the struggle to get the airplane in and out of the hangar.

Singing my song.  Does a number on currency, though.