Time to talk about Allegro's

Talk about airplanes! At last count, there are 39 (and growing) FAA certificated S-LSA (special light sport aircraft). These are factory-built ready to fly airplanes. If you can't afford a factory-built LSA, consider buying an E-LSA kit (experimental LSA - up to 99% complete).

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theskunk
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Re: Time to talk about Allegro's

Postby theskunk » Fri Nov 16, 2012 10:06 pm

Frank/etc,

I'm thinking about getting checked out in the Allegro since its the closest rental available to my house -- anything I should know (or instructors you'd recommend at b bar d?) prior to going?

I've looked at the online schedule and it looks like there is good availability this weekend, and I'm heading to richmond on Wednesday to visit a friend in town for the holiday and I'd love to fly up instead of drive... ;)

Also, anybody in the RDU area looking to buy on of these and in need of a partner?

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Re: Time to talk about Allegro's

Postby FrankR » Fri Nov 16, 2012 11:08 pm

Schedule time with Jim.

Club... I'm in.
Frank
Fayetteville, NC

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Re: Time to talk about Allegro's

Postby theskunk » Sat Nov 17, 2012 11:04 pm

Well -- I went up with Jim today from B-Bar-D aviation and got checked out in an allegro 2000. I also discussed with him a few other aircraft that they had there, some are being put on the flight line for rental (not primary instruction) while they are for sale, and a few are looking for some potential limited-rental partnership.

My biggest question coming out of the check ride, I still don't have a good handle on how the various engine models affect the cruise speed. It seems that the allegro, while a well designed/finished aircraft, doesn't strive for much more than about 105kts, which is fine, but I'd like a little more of a list of which aircraft gets what cruise speed.

If you all haven't noticed yet, I'm more of a 'go somewhere cool and fun, and have a fun unique experience getting there' than a 'lets to fly holes in the sky' sort of guy.

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Re: Time to talk about Allegro's

Postby drseti » Sat Nov 17, 2012 11:44 pm

theskunk wrote:I still don't have a good handle on how the various engine models affect the cruise speed. It seems that the allegro, while a well designed/finished aircraft, doesn't strive for much more than about 105kts


In most LSAs, cruise speed isn't so much determined by the engine as it is by airframe drag and propeller pitch. With ground-adjustable propellers, you can pitch for up to 120 KTAS at sea level, ISA standard day, max continuous power (i.e., the LSA limit) -- and sacrifice climb performance. Or, you can go for finer pitch on the prop, improve takeoff and climb performance, and take the penalty in cruise speed. You can clean up the airframe (wheel pants, gap seals, aerodynamically sleek composite fuselage, tapered wings) and get good cruise speed, or you can make the interior more comfortable, and everything external more accessible for maintenance, and give up some speed. It's all about trade-offs. Those LSAs used by flight schools as primary trainers are generally set up for maintainability, access, and climb performance, so their cruise speed is somewhat below the LSA max (my SportStar fits this description, and cruises at 105 KTAS). Those marketed as personal hotrods usually have the prop pitched coarser. They may have less cabin width and comfort, less maintenance access, longer takeoff rolls, and reduced climb performance, but they will make the 120 KIAS speed limit. Also, shifting the CG aft increases cruise speed (but restricts your loading envelope). Everything in aeronautics is always a tradeoff.
The opinions posted are those of one CFI, and do not necessarily represent the FAA or its lawyers.
Prof. H. Paul Shuch, Ph.D., CFII, LSRM-A/GL/WS/PPC, iRMT
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Re: Time to talk about Allegro's

Postby Jack Tyler » Sun Nov 18, 2012 7:32 am

"If you all haven't noticed yet, I'm more of a 'go somewhere cool and fun, and have a fun unique experience getting there' than a 'lets to fly holes in the sky' sort of guy"

IMO you've hit on the critical issue WRT pilots earning their license and then, within a year or three, drifting away from flying altogether: few if any long term flying goals. And if you really long for fun, interesting places to fly, an alternative way to look at any given a/c is not how far you can go on a gallon of gas or hour of time, but where it will let you land. After all, that's the key for you, not distance. E.g. Visit www.theraf.org and think about our mission, which is to preserve and open up back country airstrips. Right now I'm camping next to a wonderful grass airstrip (also seaplane landing, look up 01FL) among a group of other RAF folks, and the mix of a/c is very broad but the pleasure of sitting around the campfire last night was mutually satisfying. Flying to the $100 hamburger isn't very sustaining because, once you get there, you're just in another restaurant with a group of strangers. Flying into an airstrip located in a peaceful, natural setting and getting acquainted with others doing the same thing doesn't require much distance flying. And some of the LSAs are ideal for landing on shorter fields.

If this idea tantalizes you, consider that a RAF state liaison for South Carolina is just now being announced (Kathleen Helgenberger) and she can help you plug into this kind of flying. Also consider joining Team RAF (use the link on the left pane of the home page). You can start as a non-donor so no cost to you. It's a great group of folks, fast growing aviation charity and, for the second year in a row, voted a winner of the Lightspeed Foundation award by those involved in aviation.

Jack
RAF Florida State Liaison
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Do you fly for recreational purposes? Please visit http://www.theraf.org

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Re: Time to talk about Allegro's

Postby CharlieTango » Sun Nov 18, 2012 6:26 pm

drseti wrote:..In most LSAs, cruise speed isn't so much determined by the engine as it is by airframe drag and propeller pitch. With ground-adjustable propellers, you can pitch for up to 120 KTAS at sea level, ISA standard day, max continuous power (i.e., the LSA limit) -- and sacrifice climb performance. Or, you can go for finer pitch on the prop, improve takeoff and climb performance, and take the penalty in cruise speed. You can clean up the airframe (wheel pants, gap seals, aerodynamically sleek composite fuselage, tapered wings) and get good cruise speed, or you can make the interior more comfortable, and everything external more accessible for maintenance, and give up some speed. It's all about trade-offs. Those LSAs used by flight schools as primary trainers are generally set up for maintainability, access, and climb performance, so their cruise speed is somewhat below the LSA max (my SportStar fits this description, and cruises at 105 KTAS). Those marketed as personal hotrods usually have the prop pitched coarser. They may have less cabin width and comfort, less maintenance access, longer takeoff rolls, and reduced climb performance, but they will make the 120 KIAS speed limit. Also, shifting the CG aft increases cruise speed (but restricts your loading envelope). Everything in aeronautics is always a tradeoff.


You are making the wrong trade-off. Its not speed vs cruise instead it is speed vs economy. A race prop is a climb prop.

2 Considerations. 1) most LSA are using 912s 2) with a 912 optimizing for speed is the same as optimizing for climb unless you pitch to use RPM above 5,500.

My CT will cruise at 125kts in the winter and that requires a flat pitch not a coarse pitch. 49" in cabin width as well and a 3 second take off roll.

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Re: Time to talk about Allegro's

Postby drseti » Sun Nov 18, 2012 7:04 pm

CharlieTango wrote:My CT will cruise at 125kts in the winter (emphasis added)


That's very good performance. It's also not surprising, since in the winter your increased air density gives you three advantages:

    More power from an air-breathing engine
    More thrust from an air-biting propeller
    More lift from an air-surfing wing

The LSA speed limit of 120 KTAS is defined at sea level, ISA standard day, and max continuous engine power. I'm sure under those conditions, your CT clocks under 120 kts. :wink:

I'll be the first to admit that composites tend to be faster (more aerodynamic airframes) than both metal and fabric airplanes. They also tend to give you an empty weight a bit less than metal, and maybe a touch more than fabric. All in all, a very good tradeoff. As for the Rotax 912ULS, I agree that fuel economy is a significant consideration. All the 912 equipped LSAs do rather well in that regard, with the faster ones obviously doing a little better.
The opinions posted are those of one CFI, and do not necessarily represent the FAA or its lawyers.
Prof. H. Paul Shuch, Ph.D., CFII, LSRM-A/GL/WS/PPC, iRMT
AvSport of Lock Haven
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http://AvSport.org
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Re: Time to talk about Allegro's

Postby drseti » Sun Nov 18, 2012 8:17 pm

CharlieTango wrote: with a 912 optimizing for speed is the same as optimizing for climb unless you pitch to use RPM above 5,500.


I pitched my prop to give just under 5500 RPM in low-altitude level flight at WOT. That way, I get optimum climb performance without risking an engine overspeed in cruise. I'm pretty sure a coarser pitch would improve my cruise speed, but degrade takeoff and climb performance.
The opinions posted are those of one CFI, and do not necessarily represent the FAA or its lawyers.
Prof. H. Paul Shuch, Ph.D., CFII, LSRM-A/GL/WS/PPC, iRMT
AvSport of Lock Haven
fly@AvSport.org
http://AvSport.org
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Re: Time to talk about Allegro's

Postby drseti » Sun Nov 18, 2012 8:21 pm

Jack Tyler wrote: Visit http://www.theraf.org and think about our mission,


This is the first I've heard of RAF, Jack. Interesting organization! Thanks for the heads-up.
The opinions posted are those of one CFI, and do not necessarily represent the FAA or its lawyers.
Prof. H. Paul Shuch, Ph.D., CFII, LSRM-A/GL/WS/PPC, iRMT
AvSport of Lock Haven
fly@AvSport.org
http://AvSport.org
http://facebook.com/SportFlying

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Re: Time to talk about Allegro's

Postby Jack Tyler » Mon Nov 19, 2012 5:49 am

I should post a dedicated thread on the RAF just to catch folks' attention. Some wonderful destinations all around the country are especially accessible to some LSA models.

Jack
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Re: Time to talk about Allegro's

Postby CharlieTango » Mon Nov 19, 2012 7:55 am

drseti wrote:
CharlieTango wrote: with a 912 optimizing for speed is the same as optimizing for climb unless you pitch to use RPM above 5,500.


I pitched my prop to give just under 5500 RPM in low-altitude level flight at WOT. That way, I get optimum climb performance without risking an engine overspeed in cruise. I'm pretty sure a coarser pitch would improve my cruise speed, but degrade takeoff and climb performance.


Best climb for 5 minutes requires pitching for 5,800 at an altitude within 5 minutes climb from your take-off altitude.

A courser pitch would only slow you down and diminish fuel economy while degrading climb as well. I'm not pretty sure, I'm positive.

At your current pitch you are unable to realize max power at any altitude. Preventing over speeding is intuitive and even permissible for up to 5 minutes so why not have all the power available? You can't teach to not over speed if you are preventing it with a coarse pitch.

Your best available speed comes at 7,500' DA pitched for 5,500 WOT at that altitude.

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Re: Time to talk about Allegro's

Postby deltafox » Mon Nov 19, 2012 8:09 am

RAF; not to be confused with RAFS. http://www.r-a-f-s.org/index.html
Dave

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Re: Time to talk about Allegro's

Postby drseti » Mon Nov 19, 2012 12:22 pm

CharlieTango wrote:Preventing over speeding is intuitive and even permissible for up to 5 minutes so why not have all the power available? You can't teach to not over speed if you are preventing it with a coarse pitch.


Yes, preventing overspeed is intuitive -- for you and me. But, no matter what I teach, you know full well that some student or renter, some day, is going to level off and forget to wind the throttle back. For a primary trainer that's also used as a rental, I really don't want to risk having the engine trashed. So, I'll gladly give up a bit of performance to protect my investment.

But yes, I do understand that my setup is less than optimum. My point is, it still gives pretty good performance. These 912s are an amazing engine!
The opinions posted are those of one CFI, and do not necessarily represent the FAA or its lawyers.
Prof. H. Paul Shuch, Ph.D., CFII, LSRM-A/GL/WS/PPC, iRMT
AvSport of Lock Haven
fly@AvSport.org
http://AvSport.org
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Re: Time to talk about Allegro's

Postby zaitcev » Mon Nov 19, 2012 2:01 pm

drseti wrote:But, no matter what I teach, you know full well that some student or renter, some day, is going to level off and forget to wind the throttle back. For a primary trainer that's also used as a rental, I really don't want to risk having the engine trashed.

I don't think you can protect against overspeed this way, because the other day the same renter is going to find an ascending air (a mountain wave) and the same result is going to transpire. Heck, even easier: he's going to descend to his destination by pitch control. Your only insurance is flash trace in your engine monitor, and your attorney.

All simple airplanes I flew would overspeed at WOT, and that includes Remos GX. In fact Michael made it easier to do by making the pitch finer. Now every time I go to Denver it's a fight with a throttle: up, down, up, down. Every descending air it's WOT at Vy and still losing (Chuck even asked me "did you lose that 1000 ft on purpose" when we crossed La Veta pass with tailwinds). Every ascending air it's pull back. No idea what other renters are doing, but that engine went through 1000 hours recently.

The other day I flew an hour of T-6 (SNJ). In that thing the airspeed range is so great that we just left the power at 27" and did aerobatics without touching the throttle or prop. If LSAs were 3x faster than they are, it would be completely feasible in them too.

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Re: Time to talk about Allegro's

Postby drseti » Mon Nov 19, 2012 2:32 pm

deltafox wrote:RAF; not to be confused with RAFS. http://www.r-a-f-s.org/index.html


Thanks for that link, Dave. I have a good friend (retired Navy, local flight instructor) who flew Stoofs. If he doesn't know about this yet, he will shortly!
The opinions posted are those of one CFI, and do not necessarily represent the FAA or its lawyers.
Prof. H. Paul Shuch, Ph.D., CFII, LSRM-A/GL/WS/PPC, iRMT
AvSport of Lock Haven
fly@AvSport.org
http://AvSport.org
http://facebook.com/SportFlying


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