Sky Arrow trip to 13,500' (first one!)

[FastEddieB]

Well, it was a gorgeous, relatively warm day in the N GA mountains, and I decided to take the Sky Arrow to new heights!

I took off from Blue Ridge Skyport (57GA), which has a field elevation of about 2,000’, and did a timed climb to 13,500’. I used the climb speed recommended in the POH - 65k below 5,000’ and 60k above. Took about 24 minutes overall to 13.5k.

Here’s a screen shot of the numbers I got in the climb:




And here are photos (check out some of the groundspeeds while headed west into a westerly wind!):

Climbing through 8k:



Climbing through 10k:



Climbing through 12k:



Climbing through 13k:



Level at 13.5k:



Based on these full-throttle rpms, I’d say my Warp Drive prop is pitched towards cruise - maybe even too much so. Its as it came from the factory, but the plane might actually cruise faster with a finer pitch to let it rev some more.

I’d also point out the Sky Arrow is a LOT slower than a CT. I’m not sure why - with the tandem seating the frontal area seems small, though I guess pushing a nacelle through the air takes add’l power. And the prop has to deal with disturbed air. Anyway, there must be a reason.




In any case, I can’t really say the mixture felt too rich at altitude. I took a little video while cruising at 13.5k - its hard to tell but the air was smooth and so was the engine.

http://www.youtube.com/profile?user=fas ... HJ20SyMIjY

Overall, fun flight on a gorgeous day!

(note: cross-posted to the CT Design unofficial site. i don't know who might be on one but not the other).

[tadel001]

The sky arrow is definitely a blast to fly. The plane always looked faster than many of the other LSAs but the dihedral and airfoil design create drag. To the benefit of the Sky Arrow, the wing design makes a very stable and easy to fly airplane. Landing that plane in cross winds is very easy. It also makes it a very comfortable plane to fly on long cross countries. I have taken it from Maryland to Texas, Florida, Wisconsin, NY, Georgia, etc. etc.

[zaitcev]

I’d also point out the Sky Arrow is a LOT slower than a CT. I’m not sure why - with the tandem seating the frontal area seems small, though I guess pushing a nacelle through the air takes add’l power. And the prop has to deal with disturbed air. Anyway, there must be a reason.

Here's a little table I compiled off datasheets of prospects (75% cruise):
Cessna 164 . . 118 kts
CTLS . . . . . . . . 115 kts
Elitar Sigma . . 113 kts
Sky Arrow 600 . 95 kts
AL Cub . . . . . . . 84.3 kts

Notice that Cub tools along while buring 5.6 gph. It even has an official 66% setting.

Also, Sigma uses the same Rotax as the 600, and it's an ungainly airplane. I'm wondering if the data is correct for it.

-- Pete

[CharlieTango]

I’d also point out the Sky Arrow is a LOT slower than a CT. I’m not sure why - with the tandem seating the frontal area seems small, though I guess pushing a nacelle through the air takes add’l power. And the prop has to deal with disturbed air. Anyway, there must be a reason.

cantilevered wing (no struts)
reflex flaps
prop pitch
fast/short wing
nacelle

[FastEddieB]

Good points all - I have a relatively slow plane for a variety of reasons.

But, to put it in perspective I just figured a trip from Blue Ridge, GA to Tallahassee, FL (269 nm) would take about 2:49 at 95k. A CT could do it in 2:20 at 115k, significantly faster.

But, like I said before, speed was NOT on my list of criteria when searching for an LSA a few years ago. I'm pretty much retired, and not in any hurry, and enjoy flying - so an extra :29 in the air is not necessarily a bad thing.

That said, there are two reasons I wouldn't mind more speed for any given fuel flow - increased range and increased efficiency (mpg). The easiest way for me would be wheel fairings, but there's the weight penalty to consider.

Oh well, at least Sky Arrows LOOK fast!

[ibgarrett]

Obviously not done as a Sport Pilot... *koff*... 13k feet...

Very cool nevertheless.

[FastEddieB]

Posted: Wed Jan 20, 2010 10:27 pm Post subject:
Obviously not done as a Sport Pilot... *koff*...

OH NOES!!!!


Seriously, I have other "credentials"...

http://sportpilottalk.com/viewtopic.php?t=1380

[KSCessnaDriver]

Looks like you had a good climb going at 13,500. Wonder how much higher it would have gone. What's the limitation for the airplane?

Nice pictures by the way.

[rfane]

Wonder how much higher it would have gone. What's the limitation for the airplane?

I have no idea what the Service Ceiling is for the plane. Limitation on the plane would depend on atmospheric conditions, terrain, and winds. Find some good thermals and rising winds off the mountains, and ride them up.

[FastEddieB]

Wonder how much higher it would have gone. What's the limitation for the airplane?

I have no idea what the Service Ceiling is for the plane.

The service ceiling for the Sky Arrow is listed as 13,500', though the fact that I chose to go to that altitude was in fact a coincidence. My main consideration was that oxygen is required above 14,000' (see below).

I apologize in advance if some of the below is known to most of the pilots on this site. I know there are both new and wannabe pilots frequenting this site and this is largely for them:

1) Service ceiling on a single engine is defined as the maximum altitude the plane can still maintain a 100 fpm climb. It assumes:

a) a standard day at that altitude (temp/lapse rate/barometer/humidity)
b) maximum gross weight
c) most forward CG (least favorable from a performance standpoint)

You can already see a problem with "b" - you will always be below max gross by the time you climb to the ceiling, even if you took off at max gross.

2) Service ceiling is not normally a limitation - you can climb as high as you want, consistent with other regs.

3) Absolute ceiling is where the airplane absolutely cannot climb any more. As a trivia point, at the absolute ceiling Vy has gradually gone down in the climb, while Vx has gradually gone up - at the absolute ceiling they are the same, and academic, since even at best rate there would be no climb available. Any other speed would result in a descent.

4) POH's may list a "Maximum Operating Altitude". Here's an example from the Cirrus POH:



This will be found under Section 2 of a POH and is a limitation. You cannot legally go higher. In the case of an SR22, there's plenty of power to climb higher, but the Cirrus was certified to standards that would change at 18,000'. The Cirrus Turbos now have a supplement amending that Maximum Operating Altitude to 25,000'.

5) Don't forget oxygen! Above 12,500' its required for that time in excess of 30 minutes. Above 14,000' the pilot must use continually, and above 15,000' the passengers must at least be supplied with oxygen.

As a practical matter, I'm 60 and I know a day spent at 8,000' or above without oxygen will result in one tired pilot, esp. the following day. I would not choose to spend more than an hour or two above 8,000' without oxygen.

Hope somebody learned something from the above!

[KSCessnaDriver]

As a practical matter, I'm 60 and I know a day spent at 8,000' or above without oxygen will result in one tired pilot, esp. the following day. I would not choose to spend more than an hour or two above 8,000' without oxygen.

Hope somebody learned something from the above!

Absolutely! I've spent a fair amount of time up at 11,000 feet in a Diamond DA-40. VFR flying, during the day, on an IFR flight plan wasn't bad. Didn't really feel bad. Compare that to flying along at 12,000 feet, in IFR with moderate precip, and I could feel the effects of altitude. I quickly decided it was best to try to get back down to 10,000 feet. At night, I don't know that I'd want to be much above 8,000 feet without oxygen, and I'm only 20.

[CharlieTango]

my house is above 8,000' and i spend 24/7 from 8,000' to 11,000' (i'm 56)

i don't do well hiking above 14,000'

when i fly i like 02 @ 12,000' in the day lower at night.

[drseti]

As a practical matter, I'm 60

Ah, you're a youngster, Eddie! (I'm 63.) But I notice from the photo of your young wife, posted elsewhere on this site, that you're every bit as much a scoundrel as I am! Here's a picture of my child bride:




(OK, I'll admit that picture is thirteen years old. But she still looks that good to me!)

We're a couple of lucky old codgers, aren't we?