Justin's Raven Build (now engine change)

The Raven type of aircraft.

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heisan
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Re: Justin's Raven Build

Unread post by heisan » Mon Nov 18, 2013 10:41 pm

Weekend weather has not really been playing along recently. Conditions were pretty bumpy, but I went up on Sunday afternoon anyway. Way too rough to get any usable readings, but who cares, I had a good flight!

Got one nasty fright when the engine started missing. Quick glance at the instruments showed the EGT creeping past 760C. Pushed the mixture to full rich, and all was peachy. Seems I need to add a friction mechanism for mixture too, as it seems to wander over long periods.

Also had trouble keeping the CHTs down. Temps were 35C+ at 6500', and #3 and #4 were hovering just over the yellow line. Had to run very rich to get it 'green' again. May need to tweak the baffles a bit more for summer flying.

The landing was also probably the most challenging I have faced in a long while. Directly into the setting sun, and thermic as hell. Fortunately the plane is very responsive, and I managed a safe (if rather inelegant) landing. Final round out and flare was done looking out the side window, as the final glare and strobe through the prop were just too disorienting to look straight ahead. Going to be a touch couple of weeks now, as the sun will be pretty much directly in line with 27 in the afternoons now, and the prevailing winds make 09 a no-no.

Some pics from the flip (first away flight BTW)...
20131117_171535_1.jpg
20131117_170626_1.jpg
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Re: Justin's Raven Build

Unread post by Jean Crous » Tue Nov 19, 2013 8:56 pm

:D Really nice to see you are enjoying your hard work Justin.
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Re: Justin's Raven Build

Unread post by heisan » Mon Nov 25, 2013 11:38 am

There was some really good weather on Sunday afternoon, so I managed to get a good set of climb and dive tests in:
climb_dive.jpg
The good news is that the numbers were pretty good this time. Speeds stable within +/- 1kt for over 1 minute each time. Gave me some good numbers to work with. The bad news is that the resulting plots do not 'peak'. I started the low end of the tests at 55kts for a dive and 60kts for the climb (Vref is 57kts). So, best climb, and best glide speeds will be somewhere below Vref - but seeing as I will not climb/dive in those ranges, I will not even bother testing at those speeds.

Had a nasty scare doing the tests though. Was doing them in the circuit to have a 'safe' place to do them, as I would have to focus on the instruments a lot. Only to have a Pipestrel fly over about 300' above me - he flew straight through the circuit (below circuit altitude) without a single radio call. But I suppose I was primarily at fault here, as I was not maintaining a good lookout...

Best climb at 60kts (with the nose seemingly pointed straight at the sky) was 440fpm with nearly full tanks. Loading pax is still going to be marginal.

The long flat bit towards the end was a scenic cruise at 22" MAP (75% cruise) out to Bronkhorstspruit, and further East. Trues out at 89KTAS burning around 16l/h.
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Re: Justin's Raven Build

Unread post by heisan » Tue Jan 07, 2014 12:08 pm

Had a short break from testing due to: broken trim servo (my fault), wx, social obligations, Christmas, etc. But I am back to testing again.

Still trying to tune the prop. I have tested with the original 57x36 prop, and there was surprisingly little difference in performance, so I have now started trimming the 60x32, to try and get the engine to the top of the torque band (3400RPM). I am now down to 58" (probably around 33" pitch). Cruise RPM @ 75% power is now 3250RPM. So ideally, I still want around 150RPM more to get the most out of the engine - but I have a feeling that shortening the prop any more will start seriously reducing prop efficiency...

Climb performance is difficult to judge with the current weather. Average climb over 1000' was 480fpm on Sunday, at 405kg take-off weight. BUT DA on the ground was 7500' (8500' at the top of the climb). So real-world performance should be a bit better. I will bring some tile cement bags on Saturday, and start pushing it towards MAUW. Will finally see if it is a two seater, or not...

A really ugly snap out of the side window - just to prove it really is still flying ;) :
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Re: Justin's Raven Build

Unread post by heisan » Mon Jan 13, 2014 1:31 pm

Someone was asking for a video of take-off and climb performance (to compare to the first flights):



This was 1 up and 1/2 fuel. 7200' density altitude, 10kts 90 degree cross wind. Average climb rate to circuit height (1000') was 490fpm.

Still marginal, but substantially better than climbing out at 75kts due to inaccurate static pressure!
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Re: Justin's Raven Build

Unread post by Jean Crous » Tue Jan 14, 2014 6:15 pm

Hi Justin, how are the tenps on your engine ? Enjoy the flying
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Re: Justin's Raven Build

Unread post by heisan » Wed Jan 15, 2014 10:40 am

Jean Crous wrote:Hi Justin, how are the tenps on your engine ? Enjoy the flying
Jean.
Temps are OK. Not great, but OK. #1 and #2 never go above 170C. #3 tends towards the high 180s. #4 I need to keep the EGTs below 660C to keep it below 190C. Oil is in the low 80s.

Going full rich, I can climb indefinitely at 60kts, without any CHT exceeding 190C.
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Re: Justin's Raven Build

Unread post by heisan » Mon Mar 03, 2014 11:08 am

Well, I think I have solved the performance issues... Ordered a factory overhauled Jab 3300 this morning ;) .
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Re: Justin's Raven Build

Unread post by JvTonder » Mon Mar 03, 2014 11:57 am

Ok if 120hp can't do it then you must chuck the plane. So when will you get the motor and install it?

=D>
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Re: Justin's Raven Build

Unread post by heisan » Mon Mar 03, 2014 12:05 pm

JvTonder wrote:Ok if 120hp can't do it then you must chuck the plane. So when will you get the motor and install it?

=D>
The engine is in the queue at the factory. Parts a drawn from inventory. Scheduled to start work in two weeks time, delivery not long after.
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Re: Justin's Raven Build

Unread post by Jean Crous » Tue Mar 04, 2014 5:18 pm

:twisted: :twisted: and the Aero-Vee... :?: .... :!: ...... :idea: :idea: :idea: ............OLX it..= SELL IT :lol:
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Re: Justin's Raven Build

Unread post by heisan » Tue Mar 04, 2014 5:21 pm

Jean Crous wrote::twisted: :twisted: and the Aero-Vee... :?: .... :!: ...... :idea: :idea: :idea: ............OLX it..= SELL IT :lol:
Yup - will need to try and sell it. May even get back a small fraction of what I spent on it :( .
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Re: Justin's Raven Build

Unread post by buffet » Tue May 20, 2014 6:40 pm

Hi JUstin
MY name is willie from FAEL and would like to make contact with you regarding the VW motor you were bateling with can you give me your cel number please.
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Re: Justin's Raven Build

Unread post by Jean Crous » Wed May 28, 2014 8:08 pm

:D Justin how are things progressing your end ?
J
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Re: Justin's Raven Build

Unread post by heisan » Wed May 28, 2014 9:00 pm

Jean Crous wrote::D Justin how are things progressing your end ?
J
Somewhere on the ocean... Apparently ordering an 'off the shelf' engine mount was a bad idea - taking much longer than having one manufactured locally. Should be offloaded at George any day now though.

Justin
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