Trimming a Rocket for Landing

[rocketman]

When you land the Rocket, where do other owners trim for landing? I use full flaps and full trim up which makes landing this plane very easy - in fact easier than my 201 which I have had much longer. But my question is, what happens when you have a real emergency aborted landing, go around occurrence in a Rocket configured this way. Without quickly adjusting the trim with full power, the Rocket would be, well a real Rocket with a very high pitch trim and uncorrectable with as much force as one pilot could muster on pushing the yolk forward. The electric trim is very slow in a 231 Rocket conversion so the manual trim would be necessary to get the trim down fast. 

 

I heard putting a 35 pound ballast in the baggage compartment would allow the plane to make normal landings with the flaps and trim set for takeoff. And others on some other posts did not notice a difference. 

 

For the other Rocket owners, how do you approach your trim settings for landings?

[AndyFromCB]

i've done a ton of go arounds in my Bravo, trimmed all the way back, flaps set for landing, gear and speed brakes out and the yoke force is more than manageable. Even trimmed all the way back, the pitch is fine until you start removing flaps, so trim down first, then slowly retract your flaps. Quite frankly, a mooney climbs just fine with full flaps down. They are pretty useless.

[Omega703]

I fly with more than 35 lbs of luggage in the back and don't notice any difference in flight. A ballast is a waste of useful load and fuel IMO. It took me a few landings to get the trim dialed in, but in my '80 231 conversion, I manually trim (agree electric trim is too slow) to where the trim indicator touches the bottom of the 'm' on the word 'trim' (just left of the indicator). This makes the controls light at 80kias. For go arounds vmc, I use forward pressure as required to establish a climb away from the ground and 107kias while manually trimming forward. For go arounds imc, I use forward pressure as required to establish a climb in a 3 degree nose up attitude while trimming for 107. As a technique, once I am above msa (imc) or clear of obstacles (vmc) I trim for a climb at 120 as it runs my cylinder temps about 10 degrees cooler.

[Omega703]

I forgot to mention- I dump the flaps at 100kias on go arounds, and I use 'four potatoes' (landing flaps) for landings. (Count for potatoes while depressing the flaps switch and you set landing flaps without looking, two potatoes for take off flaps). I've broke myself of the habit of using take of flaps for landing and have enjoyed shorter role outs and less brake wear ever since.

[David Mazer]

I can tell you from personal experience that you can't hold the nose down with full power and trim with just one hand.  You'll have to use the electric trim.  I don't use full trim up just for that reason.  Been there and done that, once.  I was pushing so hard I was worried the yoke or seat would break before I could get the trim down.  As far as the Bravo comment, not really so applicable.  The extra 10 in gives the elevator a lot more authority.  That's the reason the extra room was added.

[AndyFromCB]

I can tell you from personal experience that you can't hold the nose down with full power and trim with just one hand.  You'll have to use the electric trim.  I don't use full trim up just for that reason.  Been there and done that, once.  I was pushing so hard I was worried the yoke or seat would break before I could get the trim down.  As far as the Bravo comment, not really so applicable.  The extra 10 in gives the elevator a lot more authority.  That's the reason the extra room was added.

Correct, sorry, I forgot that Rockets are medium length Mooneys. Almost a foot of arm movement does make quite a bit of a difference, I suppose.

[aviatoreb]

I never look at the position of the trim tab while on approach. I trim by feel.  I set up by speeds and neutral trim.  I generally look for 90kts, then 85kts on approach for landing.  I then used to look for 80kts over the fence - so call it that for now.  All the while I am pitching for those speeds and trimming to take off the pressure.  Just tapping the auto trim on my yoke to take off the pressure.  Then from there I am pushing or pulling the yoke to pitch as needed to flare - by feel - and then land with yoke pressures to keep pressure off the nose and on the mains.  But that is from ~80kts which is where I have trimmed to just before the time the flare begins (adjusted for cross winds possibly).  The only thing that has changed lately is that this last speed is done by my AOA indicator now that I have it installed.  I am trimming away pressure starting at 90kts on  long final, so that eventually I am at neutral pressure and indicating about 1 dot above the blue dot (which at medium weight seems to be ~80kts - but it can be +/-4 or 5 kts depending on my landing weight).  My landings have been much more perfect every time at every weight since the new AOA and I am transitioning entirely from IAS to AOA somewhere around 85IAS and not really looking at IAS anymore as it is getting busy and close to the ground - plus the lights are easier to see out of the corner of my eye.

 

ANyway the point is that I am gradually trimming of pressure to pitch for speed and a neutral trimmed off pressure.  I am not trimming for a given trim position on the trim indicator (which I am never looking at).  I am trimming for pitch, speed and feel.

[DAVIDWH]

 Believe go arounds with full uptrim was covered very well in another post. It was pointed out that full power

with landing uptrim can go South on you very quickly.

 

What I learned from reading this post was these a not carrier take offs and no need for full power quickly. Just adjust throttle for a

 

pos climb attitude while all the while trimming down.  The author recc. patience and I think that was good advice.

[David Mazer]

Erik, I'd be interested in your new IAS over the fence.  I used to shoot for 80 kts but that made my roll out very long or required heavy breaking.  Solo and 80 gal fuel I was shooting for 75-78.  With my new AOA it shows I should be closer to 71-73 kts over the fense.

 

I don't takeoff or do touch and go takeoffs with full power anymore unless it is a short field.  Takeoff power is 35" and full prop with 2500 RPM at 400 ft.  I find it tough to get the power above 30" on touch and go takeoffs until i'm well off the ground.  Otherwise I'm worried about stressing the turbo.

[aviatoreb]

Erik, I'd be interested in your new IAS over the fence.  I used to shoot for 80 kts but that made my roll out very long or required heavy breaking.  Solo and 80 gal fuel I was shooting for 75-78.  With my new AOA it shows I should be closer to 71-73 kts over the fense.

 

I don't takeoff or do touch and go takeoffs with full power anymore unless it is a short field.  Takeoff power is 35" and full prop with 2500 RPM at 400 ft.  I find it tough to get the power above 30" on touch and go takeoffs until i'm well off the ground.  Otherwise I'm worried about stressing the turbo.

 

Ummm...I can't say exactly. I have found that I have been reading AOA and looking out the window at the busy time before landing instead of AOA + IAS plus looking out the window.  I will try to report back.  I can say that it is a bit slower for sure.  I was shooting for 78-80 with 80gal and solo and now I realize that was likely at least 5kts too fast - and my roll outs have been shorter, and she has been setting down more easily without the float I was accustomed to and felt was normal.

So do you like your new AOA?

[WardHolbrook]

Trim so that you can take your hands off the controls at any point in the flight and the airplane will stay where you have it.

[David Mazer]

Ward, in a Rocket, the problem is if you need to quickly change power settings, like a go around, neutral trim on approach will get you killed.  While it makes sense to trim to neutral most of the time, I prefer to keep it trimmed a little down on approach in case I need to go around and won't have time to adjust the trim and can't fly it full power and full up trim.

[WardHolbrook]

Ward, in a Rocket, the problem is if you need to quickly change power settings, like a go around, neutral trim on approach will get you killed.  While it makes sense to trim to neutral most of the time, I prefer to keep it trimmed a little down on approach in case I need to go around and won't have time to adjust the trim and can't fly it full power and full up trim.

I admit that I've never flown a Rocket conversion, but in every other aircraft  - including every jet I've ever flown - my advise stands.  

[aviatoreb]

Erik, I'd be interested in your new IAS over the fence.  I used to shoot for 80 kts but that made my roll out very long or required heavy breaking.  Solo and 80 gal fuel I was shooting for 75-78.  With my new AOA it shows I should be closer to 71-73 kts over the fense.

 

I don't takeoff or do touch and go takeoffs with full power anymore unless it is a short field.  Takeoff power is 35" and full prop with 2500 RPM at 400 ft.  I find it tough to get the power above 30" on touch and go takeoffs until i'm well off the ground.  Otherwise I'm worried about stressing the turbo.

 

Hi David,

 

What is it you are worried about regarding neutral trim and a possible go around?  Yes, it does create a very strong up pitch if going around with full power likely causing a stall, but knowing and feeling that, I counter during go around with manual forward pressure to a proper pitch while gradually trimming off the pressure.  And I do like neutral trim pressures during landing approach and flare.

 

I am of a different mind regarding full take off power. I use full take off power of 38''/2650 as per POH.  I figure I want to get up to a safe altitude as quickly as possible.  I do not touch the power setting until after 1000ft or so since I am also of the old-wives tale opinion that problems are sometimes created during adjustments and so I do not want to adjust below 1000ft.  I know it is more pressure on the engine and turbo to go full power, but it is per design spec (actually a bit below since the rocket is a slightly down-rated version of the TSIO520NB in the C340), but at least then I am only at 100% for just roughly 60 seconds including ground roll, then 88%.  

[David Mazer]

Erik,  Sometime early on in my Rocket flying, I did a touch and go and didn't correct the trim before applying power.  I was certain the yoke or the seat was going to break from the forward force I was applying before I could get the trim down.  With all due respect to Ward's greater flying experience, I'm not going to repeat that during an emergency and will keep the trim a little more down then I might otherwise during short final just in case.

 

If the likelihood of an engine failure is higher with full power (greater strain), or even the cumulation of stress from full power events, isn't it safer to avoid that strain with 35/25 power on takeoff as a general rule?  The logic was passed on to me by a retired airline pilot who claimed that is some of the logic used by the airlines when they don't use 100% power for takeoff.  Right?  Wrong?  I'm not sure but 35/25 is plenty of power to set up an initial climb of 1,000 ft/min even when it is 95 degrees and I don't really see any longer takeoff roll as a result.  If I'm at a shorter field, I still use full power even though, as I said, I don't notice a longer takeoff roll.  Finally, I use to reduce power from 38/2650 to 35/25 at 4-500 ft.  Now I'm only making one adjustment to the prop rather than two adjustments if indeed adjusting may be a cause of a problem.

[aviatoreb]

Erik,  Sometime early on in my Rocket flying, I did a touch and go and didn't correct the trim before applying power.  I was certain the yoke or the seat was going to break from the forward force I was applying before I could get the trim down.  With all due respect to Ward's greater flying experience, I'm not going to repeat that during an emergency and will keep the trim a little more down then I might otherwise during short final just in case.

 

If the likelihood of an engine failure is higher with full power (greater strain), or even the cumulation of stress from full power events, isn't it safer to avoid that strain with 35/25 power on takeoff as a general rule?  The logic was passed on to me by a retired airline pilot who claimed that is some of the logic used by the airlines when they don't use 100% power for takeoff.  Right?  Wrong?  I'm not sure but 35/25 is plenty of power to set up an initial climb of 1,000 ft/min even when it is 95 degrees and I don't really see any longer takeoff roll as a result.  If I'm at a shorter field, I still use full power even though, as I said, I don't notice a longer takeoff roll.  Finally, I use to reduce power from 38/2650 to 35/25 at 4-500 ft.  Now I'm only making one adjustment to the prop rather than two adjustments if indeed adjusting may be a cause of a problem.

 

Hi David,

 

There are two points here.

 

To the first - to trimming for zero pressure or trimming in case of go around.  Now that I think about it - I am in the habit of putting in power gradually during go around - esp if it is a go around in "IMC" (in quotes as it is always in practice that I have to go missed as I choose my real IMC carefully to avoid real minimums and so far I have chosen well....but I know this is no excuse to not have good procedures).  In a missed, I momentarily fly level then start climbing as I pass the MAP then I start climbing more quickly, so it does not take a huge amount of power impulse, just gradually building to higher power, and all beginning over the beginning of the runway at maybe 200 of 400 ft, so by the time I have in 85-88% I am already coming up on 1000ft or so and I am still over the runway and climbing like a banchi at that point, but the trim is coming in nicely.  On the other hand if I am going around for a balked landing reason...if it is a deer on the runway (or an airplane or something) ....I have not had to do that but I totally see your point.  If it is a bad landing aborted - yes I have done that - those require less abrupt power change.  But I did once do an abrupt quick power increase one winter when the plow guy made a quick move toward the runway as I was about to flare and he scared me - he was not on the radio.   I totally see your point I am less worried than you about my chair rails breaking loose as I can fly the airplane just fine from the seat all the way back past the last dot on the rails resting on the back seat - I am 6'4'' but unusually long legs for my height - I toyed with flying the airplane like that at first but settled on the last dot.  As for forward pressure on the yoke - if the trim wheel can hold it, can't it take the same pressure if I apply it by hand.

 

Surely this point is not unique to the rocket?  What about the other higher power mooneys?  Or maybe the even higher power to weight ratio short airplanes like an extra 300 - anybody here with experience like that?

 

As to your second point - I have had the same thought many times.  I have changed my mind back and forth several times.  There have been at least 2 periods of a month or two where I was of the same mind as you and your ATP friend that better low power generally unless absolutely nesc.  I am currently in the full power on take off camp, partly convinced by Deakin's who says full power on take off with reasons: http://www.avweb.com/news/pelican/182179-1.html

Yes - I understand the idea that less stress of lower power ..... as you said.  I am really torn.  I would be glad to hear what other folks think.

 

It is fun on my home airport of 3700ft to be at 2000ft before I leave the gated area - but is that really necessary if lower pressures and longevity would give me say 1500ft at the same point?  So I am not convinced that in a rocket it is nesc.  But for engine manegment reasons, as I read and interpret Deakins he suggests that it is actually kinder to your engine to just run it full 100% for take off.

[triple8s]

I always approach trimmed less than neutral and a bit towards nose down so if I did have to go its not so far to get trimmed for that. Also, something to remember, the trim doesn't bear the pressure because the entire empennage is moved so there is no pressure. No trim tab or no spring helping pull against the elevator one way or the other. The mooney trim works by adjusting the angle of incidence, the more neutral the empennage is trimmed the less drag is created by the tail. If this is the case, wouldn't there be a bit of drag/braking created by landing with the trim somewhere other than neutral? If the horizontal stab is slightly off from the direction of relative wind and the elevator is deflected to counter the HS seems like this would create more drag for landing. I also set rudder trim slightly off center towards the t/o position in the "O" so if I do have to go around the right rudder is gonna be a bit easier. Thoughts?????