Approach Speeds

All,

Well, now that I am out of Phase 1 plus about 60 hrs, I am about to restart my IFR training. I have about 25 hours under the hood in spam cans. Instructors have a pretty good idea for approach speeds for the typical instrument equipped training aircraft...172, 182, Cherokee, etc. How about RVs? How about a few questions to you IFRers?

Mike Seager teaches to approach at 85 mph with half flaps at the end of downwind transitioning to full flaps on base...still maintaining 85 mph. What about for an instrument approach? What speeds have you folks found to work well? How about flap position? Let's work through an approach...the ILS 10R approach to Boise. Tower instructs to maintain 4,500 until established. What speed is good at this point...pretty much straight and level waiting for the GS indicator to work its way down? Any flaps at this point? Ok, we're now 3.6 miles out with the GS centered, pull power back and trim down a little to begin descent at same speed? move to a slower speed? flaps?

Here's what I did

My CFII let me figure that out..he was interested cus he was building a 7a like me.

But I digress. First off learning IFR in an RV is a nightmare..If you have zero (almost) hood time your in for a wake up call. Soon you will be finding ways to lessen the workload. In real life the autopilot is a life saver but of course you will want to be proficient in hand flying. I took the liberty of engaging the AP at times of high stress (like copying down a clearance) but the rest was hand flown.

So if the runway was long enough (5000' +)I would use no flaps at all. My approach speed was 100kts and about 12" of MP (C/S prop on a 360) set me up for a good glide.

Only if the runway is shorter would I use flaps as this is another thing to think about and screw up when you get to go missed.

Cheers

Frank

Actual IMC

I got my first chance to go out in some actual last week in my 150hr RV6. I have the O-360 with Catto 3-blade fixed pitch prop.

It was reported 1000' OVC and 2 to 3 miles. I flew the IKV ILS36 3 times and the GPS22 3 times. I have a TT autopilot with alt hold and tied into a GNS430.

I have practiced flying no flap approaches and about 120KIAS but in the actual the other day I was ready to try them at the top of the white arc or a bit slower (100mph) so I could use flaps. I ended up using full flaps at or outside the FAF so I could use enough power to stay on the GS. I thought it worked really good for me. I think with a CS prop it might be easier to control the speed during the descent and landing.

With full flaps I felt better about using a bit more power to keep things "warm" in an enviroment that could easily produce carb ice (60-70F).

I also like the fact that I was slowed down for the descent and in a config that allowed an easy landing (not a bunch of airspeed to get rid of along with chopping the power. It also gave me more time to keep up with the airplane.

I flew each approach first using the autopilot, then by hand. On the descent I turn off the alt hold and re-engage hold at the MDA. On the ILS I let the AP fly the nav/course while I flew the GS.

(I am a CFII but still learning from my new ride...)

Approach Speed

I am a "new" instrument pilot, got my rating just over a year ago. I have a -4 with an o-360 and Catto fixed pitch prop. I generally fly the approach at 105 knots.

Part of the reason for this is that my airplane will go from right wing heavy at high speed and power settings to left wing heavy at low speed and settings. I'm not sure why this is, other than my plane is light (975), and I have a big engine. This speed seems to be a good compromise, requiring less of a trim change in IMC. I do not use flaps until I break out and see the runway.

I do like the idea of running flaps down with some power as the previous poster mentioned. But, I have never experience carb ice in my RV in 650 hours of flying.

I had one apporach this year when I picked up significant structural ice during the approach, but there was no carb ice (that I know of). One of the things you need to be able to do is fly a faster approach (above flap extension speed) in case you pick up ice or ATC asks you to expedite for a larger airplane following. For this reason I have flown the ILS in Coeur d'Alene as high as 130 knots indicated. It really is no big deal if there is enough runway when you break out. Most instrument runways are plenty long enough, even if you break out at minimums.

Flaps at mininums

I know some of you will disagree, but I am inclined to not lower any flaps until minimums and runway in sight. That way when the @#&# hits the fan in IMC and I execute a go-around, the flaps won't be left hanging. I've known a few pilots that damaged their flap after executing a go-around. I fly the appch at 80 knots FAF inbound. Most runways with instrument approaches are long enough to handle the longer roll-out.

Chuck Olsen
Tehachapi
RV-7A

I agree

But 80kts with no flaps is getting a bit mushy isn't it?..Especially when loaded..

But I agree in principle...The less to have to mess with in a high stress environment like..mins with no runway in sight the better.

Just push the go lever (then the sequence button on the 430 after establishing a healthy climb)..This assumes your prop and mixture have been pushed forwards by the FAF.

Besides the check ride examiner won't mind one bit..but mine did ask me why I wasn't using flaps..I told him the above he said.."Good answer"

Frank

frankh said:

But 80kts with no flaps is getting a bit mushy isn't it?..Especially when loaded..

But I agree in principle...The less to have to mess with in a high stress environment like..mins with no runway in sight the better.

Just push the go lever (then the sequence button on the 430 after establishing a healthy climb)..This assumes your prop and mixture have been pushed forwards by the FAF.

Besides the check ride examiner won't mind one bit..but mine did ask me why I wasn't using flaps..I told him the above he said.."Good answer"

Frank

Click to expand...

Thats knots indicated, not mph. Not mushy at all.

wizard said:

What about for an instrument approach? What speeds have you folks found to work well?

Click to expand...

It's a good idea to get proficient flying at various speeds. It's a nice feature of RV's that they are so flexible in speed; take advantage of it.

Go out on a nice day and figure out power and prop settings for a range of approach airspeeds and descent rates in your airplane. Airspeeds spaced 20kts apart is enough; you can easily interpolate between those if you ever need to. Descent rates of zero (level flight), 3 degree glideslope, and 6 degree nonprecision descent, rounded to the nearest 100 fpm, will cover the common cases there.

Make a chart and keep it with your checklists, so you can quickly nail any profile you need without having to figure it out in real time. (Here's one we use in our RV-6, O-360-A1A, Hartzell 7666A-4: http://kokoro.ucsd.edu/docs/N976DP_settings.html. YMMV.)

Myself, other things being equal I like to fly 140 kts indicated while being vectored to the approach course, slow to 120 kts by the FAF, then to 80 kts and full flaps on short final. The numbers in your chart will let you quickly get where you need to be for each of those regimes. Of course other things are not always equal, and if ATC asks you to fly the whole thing at 140, or slow to 100 for spacing, you can do that, too.

Good luck with your IFR training and have fun with it. It is a tremendously gratifying thing to learn to do, and especially so in an RV.

--Paul

Approch speed is 1.3 of VS add a factor of 1/2 the wind componet and 1/2 the gust component reduce the factor for the steady wind over the numbers but do not reduce the factor for the gust component.
Works for everything from J3's to 747's.

wizard said:

Let's work through an approach...the ILS 10R approach to Boise.

Click to expand...

OK, I'll take a shot at this, with a bunch of caveats. This is strictly speculation, I've never actually flown the BOI ILS RWY10R, this post is marked "not for navigation".

Suppose I'm coming from the southwest doing 140 kts (which is 22" and 2300 in my plane), it's a nice smooth day, no traffic, approach is giving vectors-to-final, no procedure turn, bog-standard ILS... no reason to fly slower at this point. My last vector was "Fly heading 010, descend and maintain 4100", so I'm on a right base leg now. Then: "5 miles from USTIK, turn right heading 070, maintain 4100 until established, cleared for the ILS 10R approach".

At this point I throttle back to 17", to slow to 120 kts while maintaining altitude. (I'm not going to touch the prop until short final.) I have a 30 degree turn coming up to intercept the 100 degree localizer final approach course, and I've been vectored far enough out that I'll be intercepting the glideslope from below. Intercepting the localizer, set up my wind correction angle, and go through my approach checklist (review DA and missed approach procedure, turn on the electric fuel pump and enrichen mixture at this point).

When the glideslope needle centers, I throttle back to 12", and trim for pitch 2 degrees down, to maintain 120kts and start a 600 fpm descent. At USTIK, do the usual FAF things... start a timer and check altimeter 4028. In less than 2 minutes I'll descend a thousand feet... so every 30 seconds or so, I'll want to back off the throttle a bit to maintain 12" manifold pressure and 120 kts.

Just before the DA, the prop goes to max RPM. If I have the runway, now the job is to get slow enough to land. With the prop flat, this is pretty easy... throttle back almost to idle, and pitch up to slow while keeping on the glideslope. At the top of the white arc (87 kts), apply full flaps, and then throttle up to 13" to stay on the glideslope at 80 kts. Over the threshold, reduce power as needed to land. There's almost 10000 feet of runway there, so no particular hurry .

Anyway, that's how I imagine I would do it. Let us know how you and your instructor ACTUALLY do it.

--Paul

ifr speeds

i like a no flap approach at 120 mph, 1750 rpm, at 500 fpm descent for ILS [fp 0-360]. very simple, drop flaps, trim and land. if you are trimmed for 120 and you do all your maneuvers at that speed it is very simple. auto pilot on of course. when your out with your buddies log some approaches, when your IMC hand fly some to stay proficient. have fun in the clouds.