Sonex B models

[kmacht]

Have any of these actually been built,flown, and tested by the factory yet? I find it suspicious that they can modify the airframe and still report the same exact weight, cruise speed, to/landing distance, climb rate, etc. I thought that there was no such thing as a free lunch...

Keith

[NWade]

Noel,
I think you need to respect my friend Kip's opinion. He has flown his Jab 3300 Waiex to 48 states and out to Catalina Island among other remote areas. He is a highly experienced international corporate jet pilot so he knows a thing or two.

Jake - I appreciate you coming to Kip's defense. I phrased my statements as questions because they are that: Questions. I didn't accuse Kip of anything or belittle him, and I certainly don't want to turn this thread into a religious war over powerplants. I quite literally do not understand why some people put such a high priority on a certified engine, and what I'm trying to do is wrap my head around it. Hearing people express what they see in such a solution will help me. I also want to allow for the possibility that I don't know something about certified engines that they do. Maybe this questioning approach is my IT background showing through - I am asked at work all the time for a specific solution or a specific piece of software, but often the person's underlying need is much more general; or sometimes its quite different than what they are verbalizing. On one hand, I can't know their workflow - so I need them to talk to me about their needs; I can't dictate solutions. And on the other hand, I may know of a tool or solution that fits their needs better than what they're asking for. But neither of us knows what the right solution is until we get a common understanding of the true goal / requirements / priorities. To bring this back to aircraft building: If I didn't know about metal-working tools, I might ask someone for a lot of sandpaper to help me smooth out rough metal. Someone would have to ask me "hey, why do you want this sandpaper? What kind of rough stuff are you trying to smooth out?" in order to understand that I am trying to deal with the rough edges on all these holes I'm drilling. Only then could they describe deburring tools to me, and explain to me why that's better than buying sandpaper. :)

Kip - Fair enough, peace of mind is a legitimate factor. I do have a difference of opinion on this subject; but that's all it is. I strongly agree with Jake's comments about the whole system being safety-related. A poorly-thought-out fuel system, or unsafe wiring, or bad accessories in the engine-compartment turn the best engines into a death-trap. And I'm probably also biased because I used to wrench on race-cars of various kinds (NASCAR, SCCA, Trans-Am, ICSCC). I've help out with several different engine-builds and am blasé about a subject that used to be very intimidated by. Or perhaps I'm just egotistical enough to trust my handiwork more than I trust some faceless person who's mind is thinking about god-knows-what as they assemble an engine that they won't be hanging their butt on the line for. :P

Can we all agree that we wish we had a "B Model" airframe, though? :D

One thing I haven't seen anyone comment on yet is the proposed plastic interior panels. Awesome touch, or prone to wear and looking bad after a couple of years? And are they really lighter/better than a thin fiberglass or sheetmetal cover would be?

--Noel
P.S. Keith - No, reports are that one is under construction but not yet flying. They seem to be very confident in their numbers, but I'm very curious to see what structural changes they made to avoid gaining a bunch of weight!

[gammaxy]

Have any of these actually been built,flown, and tested by the factory yet? I find it suspicious that they can modify the airframe and still report the same exact weight, cruise speed, to/landing distance, climb rate, etc. I thought that there was no such thing as a free lunch...

From what I can tell, they really aren't adding too much weight to the structure. The fuselage sides are going to be practically the same size as before, just angled out. The floor will be a little larger. The cowl will be a little heavier. I would guess 5 lbs without the weight savings they mention and think an increase of 10 lbs would be an extremely pessimistic estimate and would include a heavier tank and larger/heavier engine mount. The extra aluminum is almost negligible.

EDIT
I think I underestimated the amount of extra weight. The floor alone will increase the weight by ~5lbs and additional material will probably be added to the glareshield and seat. I neglected that the firewall will also increase in size. It looks like some of the increase in floor space will be offset by removing material from the wings. It will be interesting to see where they are able to save weight to offset it.

[planeolbob]

Hi Everyone,
Here is a link to a few of the "WideX" details I made for the design study. It was a great fun.

https://www.flickr.com/photos/planeolbob/

Blue Skies and Smooth Air

Bob (Wide Body) Mika

[lpaaruule]

I'm surprised to see what look to be air exit vents on the side of the cowling. I had thought of doing this after attending a forum last year at Airventure. It was explained that having the air exit on the bottom of the cowling made cooling less efficient as it has the highest pressure - especially during climb.

If what I think I'm seeing is the case, I think I'll be copying what they did. I happen to be working on the cowling right now.

As for the other mods, time will tell. I'm skeptical that the company strongly stresses the importance of wheel pant to reduce drag and improve cooling, but have widened the cowling and claim the same specs as model A. Maybe the side vents make all the difference. :-)

[gammaxy]

I'm skeptical that the company strongly stresses the importance of wheel pant to reduce drag and improve cooling, but have widened the cowling and claim the same specs as model A. Maybe the side vents make all the difference. :-)

On subsonic aerodynamic shapes, typically the shape of the nose matters a lot less than you would expect. The important part is shaping the back end to avoid separation and turbulence. The main parameters for estimating fuselage drag are frontal area and wetted area (surface area). Looks like Sonex has chosen not to widen the widest part of the airplane, so the frontal area will be practically unchanged. The wetted area will increase a little, but compared to the size of the airplane I agree with their claim that the performance will be essentially the same.

Also, with the current universal cowl, the fuselage already is wider at the nose and narrower at the firewall before widening back out again, so from a purely wetted area standpoint, it could be widened quite a bit at the firewall and have the same wetted area.

The gear legs matter because they are blunt on the back side and create far more drag than a similarly-sized airfoil. I'm not completely convinced the wheelpants do much other than looks. Recently, I've been flying with no wheelpants or fairings at ~135mph. It seems like I only lost ~5mph which is less than the ~10mph I thought I saw during Phase 1. It doesn't seem quite as smooth, but that's hard to quantify.

[ihab]

I'm surprised to see what look to be air exit vents on the side of the cowling.

I am honestly watching the cowling developments with interest. I am so not an expert in this matter ;) but the issues reported here and elsewhere seem to center on (a) inadequate or uneven cooling of all cylinders on the 3300 engines; and (b) possible vapor bubbles leading to hot weather "burps" in engines with floatless gravity-fed carburetion solutions like the AeroCarb. It seems having more room in the cowl to insulate (and even blow air over) the the fuel lines, and more space to create plenums to distribute cooling air properly, could not possibly hurt.

Ihab

[fjdoug]

B for Ben.
nice to see they made similar changes to what Ben did to windshield and panel.

http://sonexaus.wikispaces.com/Ben+McGu ... +Waiex+104

Doug.

[sonex892.]

I thought of Bens plane also Doug. The vertical and wider panel is far more practical.

[Bryan Cotton]

So, I just realized there is no Xenos B model. Are they already bigger?