John Crone
New Member
Posts: 33
Home Airport: North Shore, New Zealand
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Post by John Crone on Aug 26, 2016 20:32:49 GMT
Hi folks Wow- the first person to post under Sierra! I'm the owner of a Sierra RG in New Zealand in which I've flown some 340 hours from one end of the country to the other. Here the RG is still classified as a microlight which is great for us old fellows. She has pneumatic retractable gear which works brilliantly and I've just upgraded the propeller to an Airmaster CSU with 3 blade Whirlwind. The photo attached has been taken from ZK-AST (the Astore above) which just happens to occupy the next door hangar. Attachments:
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Post by mackattack on Aug 26, 2016 21:23:43 GMT
That's so cool and welcome to the forum! We can't get the RG version here in the US because it doesn't meet our LSA requirements. So we are all jealous! What kind of cruise speed do you get in it? Is it the Rotax 912 ULS?
We low-wing Tecnam guys have to stick together!!
Thanks!!
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Post by Cluemeister on Aug 26, 2016 21:27:37 GMT
That is a really cool looking aircraft with the retractable gear! Welcome to the forum!
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John Crone
New Member
Posts: 33
Home Airport: North Shore, New Zealand
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Post by John Crone on Aug 26, 2016 22:14:55 GMT
Nominal cruise is 125 knots at 26 MAP and 5000 rpm. Engine is standard 912 ULS. Photo shows 122 with 129 TAS and a nice tail wind for 150 over the ground. Attachments:
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Post by mackattack on Aug 26, 2016 23:33:54 GMT
Tailwinds are the best! Thanks much!
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Post by geobuff on Aug 27, 2016 15:23:08 GMT
Nominal cruise is 125 knots at 26 MAP and 5000 rpm. Engine is standard 912 ULS. Photo shows 122 with 129 TAS and a nice tail wind for 150 over the ground. 5000 RPM is very low, and you must get a very low fuel burn. At 5000 RPM, which must be about 55% power, I only get 104 kts at 2000' altitude. I have the 912_IS. I usually fly at 5400 RPM at get 117 kts at 2000' altitude, burning 4.8 gph (lean of peak). At 9500' and 5400 RPM I still get 117 kts and burn 4.0 gph. I am curious why you fly at 5000 RPM? Flying at 125 kts at that low power rating is totally amazing. What is your speed at 5400 RPM? Must be 135 kts. Shannon (Tecnam-Sebring) keeps telling us that in Europe they reach those speeds in the micro-light category. I cannot imagine. That is totally awesome. At 130+ kts you can actually get somewhere is a reasonable amount of time on a cross country. That speed is as fast as a Diamond DA20. I am totally jealous. Geobuff
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John Crone
New Member
Posts: 33
Home Airport: North Shore, New Zealand
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Post by John Crone on Aug 27, 2016 20:34:39 GMT
Wow - you sure are using some revs. I was told to only use 5000 in cruise and in fact the Airmaster electronic control system comes with settings of 5700 for T/O, 5400 for climb and 5000 for cruise (although these are adjustable). Certainly I can go much faster with increased MAP or revs but would be exceeding the structural cruising speed. I get about 17.5 litres/hr or 7 nm/litre so range is near 700nm but the ULS is not as efficient as your IS. (sorry for the different units we're metric here!)
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Post by mackattack on Aug 27, 2016 21:34:54 GMT
Thanks! What is the Vne for your 2002 then, if you think you would exceed the structural cruising speed? I know the Astore's Vne is 150 knots for example. And it sounds like you have an adjustable propeller - here in the US we are stuck with ground-adjustable propellers for LSAs... Another advantage that you have!
If we could use an adjustable-speed propeller in flight we would probably set cruise in the 5300-5500 rpm range for a 914 (5500 is the max continuous power). You can run the turbo for up to five minutes and go above that (normally on take off).
I know the wings are the same between the 2002 and the Astore, so it's interesting to me that the max structural speed seems so much lower.
Thanks!!
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Post by geobuff on Aug 27, 2016 21:48:02 GMT
I think the Never Exceed RPM for the 912 is 5800. Anyone think different? I know I have inadvertently gone over 5800 a couple times when I was descending and not paying attention, and nothing seemed to happen. I try and never cruise above 5600, and usually keep it at 5425 so I stay in Eco-Mode. With my prop pitch, my WOT (wide open throttle at level flight) is 5625 anyway, which is the recommended WOT for a 912 with ground adjustable fixed pitch prop.
WOW, to have an airplane where you have to worry about structural cruising speed in level flight. Perhaps I need to move to NZ. I guess Shannon was not kidding when he was telling us about performance in Europe.
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Post by jetcat3 on Aug 27, 2016 22:44:06 GMT
Yeah, constant speed props completely transform these birds. Now just imagine a 914 at 10,000 ft on a super hot day. You could scream!
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John Crone
New Member
Posts: 33
Home Airport: North Shore, New Zealand
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Post by John Crone on Aug 28, 2016 1:00:57 GMT
My POH has Vne at 154 knots and Vno at 122 (but I've also seen 135 in spec sheets). New Zealand is quite a windy place and we often have to worry about turbulence so I reckon Vno applies most of the time. I haven't actually tried 5500 in level flight - I'll give it a go next smooth air trip and report back.
Yes I understand the limit for Rotax is 5800 but Airmaster use 5700 for T/O as they have a governing limit of +-100rpm.
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Post by mackattack on Aug 28, 2016 15:08:02 GMT
Glad to hear that the Vne is similar to the Astore, that makes sense to me. Thanks Hyperion that makes sense!!! One thing I am considering for my Astore down the road (after the warranty expires) will be whether to re-certify the aircraft as experimental and add a constant-speed prop. However, I won't be able to add retractable gear!!! But it would be great to cruise normally at 130+ knots. On the other hand, we will see what Tecnam does with the new 915iS engine and how the US revises its certification regulations ... so I have some time to monitor the situation.
Let us know how that 5500 rpm test goes!
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Post by Cluemeister on Aug 28, 2016 20:00:20 GMT
We always want to go just a little bit faster, don't we?
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John Crone
New Member
Posts: 33
Home Airport: North Shore, New Zealand
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Post by John Crone on Aug 31, 2016 21:13:59 GMT
Beautiful day yesterday so I tried some experiments:
5400 with 27 MAP gave me 135 knots and 28 MAP 139 knots Interesting that 5000/27 also gave 135 knots.
The other thing I tested was sink rate at 70 knots. With engine at idle and fine pitch - sink rate was 770 fpm which gives a glide ratio of 9.2 or 1.5 nm per 1000 ft. With engine off and prop feathered - sink rate was 610 fpm which gives a glide ratio of 11.6 or 1.9 nm per 1000 ft. I didn't test with engine off and blades fine but guess it would be much worse.
This was all with 1 POB and about 60 litres of fuel on board (I calculate all up 460 kg) and at altitude range 3000-4800 ft.
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Post by mackattack on Aug 31, 2016 23:50:16 GMT
135 knots ... *sigh*. Ban this SOB from the forum! *laughing and just kidding*
That's great and very interesting. The glide ratio actually is so interesting to me with the ability to feather. That can make such a difference in an emergency ...
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