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  #11  
Old 09-09-2017, 08:32 AM
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chrispratt chrispratt is offline
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I would certainly caution anyone reading the above posts to try these things at altitude first. Airspeed calibrations on E-AB aircraft vary widely as do handling characteristics in different RV models.

None of the above speeds/techniques would apply in total to my RV-8. I noticed my muscles tightening as I read some of the speeds.

Be careful. Do what works for your airplane and your flying comfort zone.

Chris
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  #12  
Old 09-09-2017, 08:33 AM
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  #13  
Old 09-09-2017, 10:29 AM
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Default RV-6a or RV-7a C/S pattern diagram

Does anyone has the C/S pattern diagram from Mike Seager?
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  #14  
Old 09-11-2017, 10:33 AM
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Quote:
Originally Posted by Plummit View Post
No image but lots of popups, which is why I used IMGUR.
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  #15  
Old 09-11-2017, 01:41 PM
scsmith scsmith is offline
 
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Quote:
Originally Posted by chrispratt View Post
I would certainly caution anyone reading the above posts to try these things at altitude first. Airspeed calibrations on E-AB aircraft vary widely as do handling characteristics in different RV models.

None of the above speeds/techniques would apply in total to my RV-8. I noticed my muscles tightening as I read some of the speeds.

Be careful. Do what works for your airplane and your flying comfort zone.

Chris
Chris, I'm interested in what in particular concerned you.
Absolutely good point on ASI calibration. My ASI reads 59 kts at clean stall! (Not that I actually get a clean stall in the -8, it just gets mushy and the sink rate goes way up) I know the instrument itself reads 3--4 kts high at that speed. (tested with a U-tube manometer). I also know that my static pressure system gives correct airspeed at 165 kt, and the altimeter reads correctly during a high-speed low pass down a runway. I can't therefore fully explain why my INDICATED stall speed is so high.

For a long time I flew patterns and approaches at 80 kt, just because it feels really solid. It gives a lot of ground-float which gives lots of time to get a smooth wheel landing (but also chews up a lot of runway). last year I slowed down to 75 kt on final, which is just one kt faster than the 85 mph mentioned by Bicyclops, when flying solo. It cuts down on ground float a lot and makes the timing of flare and getting the height right a little less forgiving, and reduces the stopping distance significantly. I still tend to fly a little faster when heavy.

Anyway, since my 75 kt is essentially the same as the RV7 85 mph recommendation, I'm wondering what concerned you and what speed/technique you use.
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  #16  
Old 09-11-2017, 03:48 PM
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To reply to the OP and disregarding the tongue in cheek post I made on the fixed pitch thread, let me submit my 2 cents worth for consideration.

These suggestions will apply to a 6, 7 or 8 with a 320 or 360 and a 2 or 3 blade constant speed propeller.

With a CS prop, we have access to essentially a gearbox, you can liken fine to low and coarse to high gear. We normally start off in low, but we don't need to stop in low, more on that later. The main power indicator becomes the manifold pressure gauge as in typical flight regimes, the propeller speed will stay fixed as selected by you (which gear you are in). So as we depart in fine we transition up the gearbox to a mid range which we climb in, say 2400rpm. Old wisdom says you don't use higher MP than RPM, but it isn't completely true, so we will climb at 24/24 so nobody gets upset. If you are at altitude, you will already know about leaning and away from the highest power settings, leaning can occur fairly lowdown and saves you a buck or two. Cruise leaning is not for here, we are going to get onto pattern stuff very shortly.

At this point, let us have a chat about safety. Any tips and suggestions I may give here on in have been refined over some thousands of hours of small and large aeroplane operation. I ran 3 large single piston aeroplanes for skydiving for close on 10 years before I went commercial - never blew a jug, all three went to TBO. I taught the new guys, I coach guys now and do transition training. What do we start with - slow speed 101 at a safe altitude in a quiet area. Once we have explored the aeroplane's envelope at slow speed, played with stalls, experimented with large scale control deflections around the stall speed and figured how it talks to us, how it warns us and where it will nip us, we can go down. First few approaches never touch the ground - don't need to because we are concentrating on placement, approach gates and the view of the approach. Take out the anticipation of the imminent impact and it is amazing how chilled the first few approaches can be.
We now have lots of safety stuff tucked away before we get onto landings, but hey - back to the thread !

So, here we are around 25 miles out at a mid altitude, we will say 5,000' agl. We've enjoyed the flight, cruised at a mid setting of 23/23, it has cost us to get up to height, our t's and p's are nice and steady and we are ready to descend. We need to be mechanically sympathetic at all times to our engine, it is expensive and quite important in the collection of bits in the whole assembly, so we don't want to shock it or damage it. Once we start on down, we can leave the rpm where it is, it is going to do us well all the way down. MP can come down a tad, though not much, say 20" - let the engine keep producing power and let the speed increase, assuming the conditions permit and are smooth. As we descend, the MP will increase, so chase it down, but keep it at 20" as much lower will take too much heat out of the cylinder heads. Mixture can be brought back to rich, or appropriate for field elevation.

We now get to about 3 miles out and decide we want to join on the 45, so let's get back to pattern speed - say 100kts (I am going to stay in kts, add 15% for mph) and by slowly reducing MP to around 12" our rocket ship will change miraculously back into a Cessna by the time we get to the edge of the pattern. Quick review for your downwind checks, trim, don't get too wide, what if it coughs now, can we get onto the field ? You should now be at 100kts, around 12"/2300. If not - experiment up aloft to find your sweet settings, have an idea what does what at what speed. Dive down to a safe altitude at high speed, hold level and reduce power and see how long the decel takes, what power settings you use on your aeroplane to get to 100kts - bank that info.

By the time we are 30 beyond the threshold in aspect, start the base and inch out some flap, trim. Guys use seconds of travel - perfect, look out and see where they are, it needs to be about 1/3, trim. Let the speed bleed by reducing MP but unless you are up at max weight and into under 1500' runway, leave the prop where it is. We should be slowing to around 75kts now, trim - look and listen. Look at the aspect, listen to the engine, remember these, then you have go to memories to call on when turning onto final in future. Make the view look the same, make the sound about the same and guess what - bingo ! 75kts, stabilised - trim.

Now - assess, do we need full flap, probably not, squeeze a bit more out and leave it there. Quick scan, trim, feet correct, all final checks done, reducing MP, let the speed come back to around 70kts, trim, bleeding through 60kts over the hedge bring the power off, rounding out and - squeak, you are down.

Bummer - you bounced - probably a tad fast, a quick check of the attitude, maybe a squirt of power and deep breath... and land.

Nailed it - breathe and concentrate on the rollout and deceleration.

Don't like it, feel out of trim, off speed - anything, slooooowwwwllly apply power and go round. Use full throttle, bring the flaps up when safe and then after a couple of seconds, bring it back to around 23" for the climbout. Deep breath, another pattern and remind yourself that everyone else goes round now and again.....

This was a long winded way of saying relax, enjoy, don't hang your hat on definitive settings and rigid procedures, use playtime with an experienced pilot to open your mind and increase your experience level on your own aeroplane.

Recap........If in doubt, don't - go to a safe place, review, re plan and repeat. Have a laugh about it afterwards and talk things through with others who you respect.

Oh - and trim
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  #17  
Old 09-11-2017, 04:37 PM
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I've had a 6a and 7a with CS IO-360. Just know what I use.
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  #18  
Old 09-11-2017, 05:18 PM
scsmith scsmith is offline
 
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Quote:
Originally Posted by mike newall View Post
To reply to the OP and disregarding the tongue in cheek post I made on the fixed pitch thread, let me submit my 2 cents worth for consideration.

These suggestions will apply to a 6, 7 or 8 with a 320 or 360 and a 2 or 3 blade constant speed propeller.

With a CS prop, we have access to essentially a gearbox, you can liken fine to low and coarse to high gear. We normally start off in low, but we don't need to stop in low, more on that later. .....

We now get to about 3 miles out and decide we want to join on the 45, so let's get back to pattern speed - say 100kts (I am going to stay in kts, add 15% for mph) and by slowly reducing MP to around 12" our rocket ship will change miraculously back into a Cessna by the time we get to the edge of the pattern. Quick review for your downwind checks, trim, don't get too wide, what if it coughs now, can we get onto the field ? You should now be at 100kts, around 12"/2300.
By the time we are 30° beyond the threshold in aspect, start the base and inch out some flap, trim. Guys use seconds of travel - perfect, look out and see where they are, it needs to be about 1/3, trim. Let the speed bleed by reducing MP but unless you are up at max weight and into under 1500' runway, leave the prop where it is. We should be slowing to around 75kts now, trim - look and listen.

Oh - and trim
My main comment about Mike's procedure here is leaving the prop at 2300. If you do at some point need to do a go-around, you want to be able to just go to full power. With the prop at 2300, you are not going to get it, and it is pretty far over square to go full throttle. Given that something is not right, warranting the go-around, you may be preoccupied enough to forget to push the prop forward before or during pushing the throttle forward. So why not just have it in fine pitch, ready to go if you need it?

So, my procedure is to go to fine pitch on downwind as part of my downwind checklist. (GUMP)
I use about 2200 rpm with a notch of flaps and that gives me 80-85 kts on downwind constant altitude. Then something like 1700 RPM abeam the numbers to start descending.
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Last edited by scsmith : 09-11-2017 at 05:21 PM.
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  #19  
Old 09-11-2017, 07:04 PM
Bevan Bevan is offline
 
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There's four benefits for moving the prop to fine on the downwind leg. The CS prop can be a big speed brake if it's in fine pitch and the RVs can benefit from some drag for landing.

1) I find fine pitch useful on downwind to get the speed down to flap speed. Leave it fine after that for additional benefits.

2) During base and final, you will have a certain combination of MP, RPM and flaps to make a standard approach. Should you lose power during any of that, moving the prop to coarse (provided the engine is still turning) to remove some prop drag and improve the glide performance considerably. Moving flaps from full to 1/2 will also help but they may not be at full yet.

3) On final with the airplane configured for drag as above (1.4x stall speed, 1.3x when you're more proficient) I round out THEN pull the power back. It will immediately sink cause there's all that drag hanging out. Hold the nose up and off even after the mains are down and until there's no more aerodynamics available with full stick back. Keep the stick full back until parked.

4) Finally, should you need full power to go around, the prop is already configured.

The above is my 2 cents worth based on my experience with RV7A 180Hp and CS prop. YMMV.

Bevan.
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Last edited by Bevan : 09-11-2017 at 07:08 PM. Reason: Missing words.
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  #20  
Old 09-11-2017, 07:21 PM
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Quote:
Originally Posted by scsmith View Post
My main comment about Mike's procedure here is leaving the prop at 2300. If you do at some point need to do a go-around, you want to be able to just go to full power. With the prop at 2300, you are not going to get it, and it is pretty far over square to go full throttle. Given that something is not right, warranting the go-around, you may be preoccupied enough to forget to push the prop forward before or during pushing the throttle forward. So why not just have it in fine pitch, ready to go if you need it?

So, my procedure is to go to fine pitch on downwind as part of my downwind checklist. (GUMP)
I use about 2200 rpm with a notch of flaps and that gives me 80-85 kts on downwind constant altitude. Then something like 1700 RPM abeam the numbers to start descending.
Steve,
A question on your comment about being over square at 2300 RPM with full throttle: My fixed pitch 0320 RV6A turns about 2300RPM on take off with full throttle. Other than not making full horsepower, what issues (damage?) do I face by running "over square"?
Thanks
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