Robin DR400/180 stick back at start of the roll

[indyaachen]

Hi all,
I've recently changed my ATO and now will be trained either Grob or Robin. I already had a flight in Robin, where the instructor showed me something that I've not done before: holding the stick in back position form the start on the runway.

Earlier in Piper, I had to hold the forward pressure to keep the nose down until 60kts ('air speed live') and at 70 kts take off.
Somehow I forgot to ask the FI why he told me to hold the stick back. I will ask him the next time. But meanwhile, if you know it'd be great to learn from thoughts.

I should mention that it is a short 480m of grass runway.

[Katamarino]

That Piper technique sounds a bit dodgy to me...

[Sir Niall Dementia]

Ouch! The Piper technique may give an extra shove upwards on rotation, but loading the nose leg like that is asking for future big trouble.

I haven't flown a DR400 for some time, but I was taught at Sywell back in the mists of time by Andre Baldet to start with the stick back and then relax the back pressure.

I'm probably way out on both counts, and have caused lots of damage as I went along.

I haven't seen a PA28 POH for years, and would be very interested if the hold it down technique is in there.

SND

[robin]

The DR400 is a lovely machine and strong. But as with all nosewheel aircraft you should lighten the load on the nosewheel. Too many pilots think their aircraft is indestructible and cause damage to the gear and engine mount - the Shoreham webcam is a great tool to see the abuse of training aircraft......

[tmmorris]

Well, the POH for our club PA28 says 'The take-off performance ... is based on a take-off speed of 78 MPH IAS (68 Kts IAS). Accelerate the airplane to this airspeed and rotate.' That's all the advice they give, although the term 'rotate' could be said to preclude holding the stick back for the whole takeoff roll.

[robin]

Driving a PA28 to 68kts before rotating sounds a bit excessive....

[tmmorris]

It does but it says it again in the performance section (adding the words 'with the flaps up and the engine at full throttle' so they definitely meant it.

[indyaachen]

Ooops ... my mistake. For Piper, it was 50 air speed alive, 60 take off, 70 climb ...

However, my question is about holding the control column back. Is it something specific to Robin?
Looking at your responses, it seems like a common technique taught for all the aircrafts. Is that so?

[9 lives]

Earlier in Piper, I had to hold the forward pressure to keep the nose down until 60kts ('air speed live') and at 70 kts take off.

Absolutely not!

Yes, hold the stick either all the way back, or at least effectively nose light, through the entire take off ground roll. PA-28's can be a little troublesome if forces off the ground too early, but any airplane would rather have the third wheel light during take off. The only exception to this are some T tailed aircraft (Tomahawk) which are better accelerated nose neutral.

Letting along the immense wear and loading being imposed on the nosewheel when it is forced down, you are setting yourself up for a wheelbarrow of the whole plane. If the mains come off before the nosewheel, the aircraft could groudloop around the nosewheel. If in doubt, search Youtube for "groundloop", and then imagine that happening to you at takeoff speed.

Every Cessna tricycle single I fly will start the takeoff with my holding the stick fully back, until the nose has come up noticeably, and then held there until it flies itself off. My technique will be similar in every other tricycle I fly, though maybe not full nose up stick held in, just enough to lighten the nose.

The notion of a rotate speed in a flight manual is a little "big airplane dreaming", during the writing. If the nose is held light, and at the right attitude, most planes will fly themselves off nicely when they are ready. The actual "rotate" is more to assure that by that speed, you are airborne (as there is not reason not to be - unless something is wrong!).

You fly the plane, it does not fly you!

[DeltaV]

I imagine the PA28 POH was written with the expectation of a hard runway, whereas the OP mentioned grass.
On grass particularly I'd expect appropriate technique to lighten the nose leg as early as possible. Conversely, I'd expect tailwheel technique to be the reverse to lighten the tailwheel as early as possible.

[Jan Olieslagers]

I was taught to keep the stick fully back during taxi AND when beginning to roll. The reason being indeed to reduce load and stress on the nosewheel and whatever carries it.

And keep it back and back until the nose wheel lifts off, from then on keep the nose pointing up as much as it does during initial climb-out. When all three wheels are off, push a bit more forward to gain some speed and retract flaps.

This is about a three-axis microlight, a typical 80 HP Rotax-powered two-seater. Mostly operated from grass. But I can see no reason to operate heavier planes differently, nor why a hard runway should make any difference. The philosophy of take-off is to be as high as possible as soon as possible, to have maximal options when the engine quits. All the while avoiding stalling, of course, by keeping sufficient airspeed.

[x933]

I aerotow with a DR400/180R and have about 50hrs (including most of my PPL) done on a PA28.

Keeping the stick back on a PA28 for that long is uncomfortable at best. You should be able to feel the aircraft starting to unstick. If you're on a tarmac runway, start with the stick in the middle and "check" back on the yoke at 60ish kts.

Brief for aerotowing in the DR400 is start with the stick on the back stop and as it starts to unstick, relax the back pressure so it flies off in a 3 point attitude - then once accelerated in ground effect to climb speed ease into the climb.

Enjoy the robin, they're lovely.

[blueandwhite]

Ooops ... my mistake. For Piper, it was 50 air speed alive, 60 take off, 70 climb ...

However, my question is about holding the control column back. Is it something specific to Robin?
Looking at your responses, it seems like a common technique taught for all the aircrafts. Is that so?

Holding the stick back is normal. But fully back for taxi etc is fairly universal. You may not wish to try that for take off in all aircraft. For instance in the Europa it can kill you! Stick control needs to be appropriate as soon as you are moving. (BTW the full forward bit sounds down right wrong to me.)

However I move the stick forward quite a bit on every take off. But I'm flying a tail dragger. If I had stick full forward to that speed I would not get airborne as my prop would be digging the runway up. Also full back for more than about 3 seconds would result in a rapid lift off followed in a few seconds by a crash.

[indyaachen]

Good that I asked this here. It seems I have unintentionally learned a bad habit and my FIs didn't notice. I'll definitely work on getting it right.

Keeping the control backward, wouldn't that mean that the aircraft could get off the ground even at a lower speed. A take off speed, I understand, is desirable for the sake of better control.

[Heston]

I was taught to imagine that the nose wheel is made of glass - and to try to keep the load off it as much as possible: in any light aeroplane (though I dare say there will be exceptions (there always are) but it wouldn't be a PA28).

[ETOPS]

Keeping the control backward, wouldn't that mean that the aircraft could get off the ground even at a lower speed

Don't think of the stick being held back as a "fixed" idea. As airspeed increases you can both see and feel the attitude of the nose beginning to rise. From that point you can "fly" the attitude by small smooth movements - with experience this can be fined tuned remarkably well. Thus as you take off in the Robin you would start with the stick fully aft then move it slightly forward as the nose becomes light then, after lift-off, move it slightly further forward to increase speed to the climb speed.....

[Capn Bug Smasher]

I am a super fan of Budd Davis over at Airbum.com whose article on the subject I found illuminating. Here it is - How Short is it Really? (http://www.airbum.com/articles/ArticleLetItTakeOff.html)

If you don't want to read it all, here is the most pertinent section:

"The procedure is fairly cut and dried but does entail just a few nuances calling on you to really see what’s happening in the windshield.

We’ll start the takeoff (we’re assuming a tri-gear airplane) as we normally would, but, as soon as the airplane is rolling fast enough that we sense some life in the elevators, we position the yoke aft of neutral and hold it there. What we’ve done is insert a nose-up command in the elevator before the airplane has enough speed to pick the nose up. Then, when the airplane accelerates through the speed required to unstall the tail and pick the nose up, we immediately release some backpressure. At the same time, we look over the nose and visually fixate on where the nose is in relation to the horizon and, from that point on, our entire focus is to hold the nose in that position

Because the airplane is accelerating, if we don’t release back pressure and set a given nose attitude, the nose will continue coming up as the airflow over the tail increases with speed. What we’re trying to do is establish a slightly nose up attitude that positions the nosewheel something like six inches off the ground. Our goal is to hold that attitude firm, which will require us to gradually ease off the backpressure as the airplane accelerates. The first few times you do it, it’ll be a little counter intuitive because we’re actually moving the yoke forward slightly as the airplane takes off. The name of the game, however, is to use the nose like a rifle sight and absolutely nail it on a given position on the horizon and hold it there no matter what.

The net result of this little exercise is that the nose will come up, the airplane will run on the mains for a few seconds and will lift off when, and only when, the lift/speed curves cross and exactly match the environment in which the airplane is operating. It’ll compensate for every single thing having to do with the takeoff and won’t leave the ground until every factor is right. This is an instance where we can’t possibly know as much as the airplane does in terms of what is needed at that precise moment, in that precise location, with that specific airplane to safely leave the ground and be guaranteed of a positive rate of climb."

[thing]

Those lift off speeds for the PA28, I'm assuming a Warrior, that have been mentioned seem excessively high, I would expect to be airborne at 55 knots or thereabouts although I would unstick an Arrow at a slightly higher speed.

Unless I'm on tarmac/concrete I always hold full back stick/yoke when taxiing in or out in a trike and have back pressure (rather than a large movement) on the take off roll for the aforementioned less stress on the nosewheel reasons. Although for sticky/long grass fields I would use whatever technique the POH for that particular aircraft stated.

Re holding back the stick, I seem to remember the mighty Phantom was full back stick on the take off roll.

[A and C]

Any one who holds the stick forward on a PA28 take off roll should not be let out without a grownup to look after him, those above have well detailed the reasons.

It sounds to me as if your former instructor is a wannabe airline pilot, forward pressure on the stick up to 80 KTS is a Boeing 737 thing to keep nose wheel steering authority untill the rudder gets some airspeed.

I would guess I am looking at about 1000 hours of DR400 time and the best way to get the aircraft off the ground on grass is to hold he stick full aft at the start of the take off run and as the airspeed increases past around 30 KTS smoothly move the stick forward to a position just aft of neutral, then at about 50 KTS move START a smooth rotation.

This assures minimum load on the nose gear and moving the stick forward after 30 KTS keeps the same nose gear protection due to the increasing effectiveness of the Stab due to increased airspeed but reduces drag and the risk of getting the aircraft into the air below the normal stalling speed due to ground effect.

Enjoy the DR400, it is without doubt the best aircraft in its class.

[BackPacker]

Specific for the DR400 (and R2160 too, btw), there is one other thing to consider.

The nose wheel is spring loaded and when there is no or virtually no weight on the nose wheel, it will "lock" in the dead ahead position. This is to reduce aerodynamic drag while in the air.

On the ground, particularly after an extremely soft landing, it is possible that the load on the nosewheel is not yet high enough to disengage the nosewheel from the lock. This means you have no nosewheel steering, and may become a problem as the speed diminishes and you also lose aerodynamic (rudder) steering.

For this reason you may want to put a little load on the nosewheel immediately after landing (check stick neutral or slightly forward of neutral). And it might also be something to be aware of when you do take-off with full stick back: You may just engage the lock before you have sufficient aerodynamic rudder authority.

[Jan Olieslagers]

Ah, ok, BP'er, that is a solid point against my little bit of wisdom, for this particular plane. As an (amateur) mechanic, I can't help feeling some doubt about the "virtually" no weight - I reckon there must be an adjustment to that, and how fragile is it? And how much care is taken on the average annual? It might be a good idea but it sounds like delicate.

[BackPacker]

A&C is more qualified to respond to that question that I am. All I can say is that at my club we've had at least one runway excursion (with damage) because of this locking mechanism, and probably quite a few near misses. Because of this, it is a specific item that needs to be covered during the checkout and club checks.

It's also a bit of an issue when manhandling the aircraft on the ground. If you push against the prop to move the aircraft backward, you also push up and thereby engage the lock. This makes it impossible to move the nosewheel with the towbar. You need to stop the aircraft, pull the nose down (by the prop) again, move the towbar to the desired steering angle, and then start pushing again. It helps a lot if you have a helper or two, pushing against the wing leading edge.

Oh, and come to think of issues, we've had two brake fires lately. One of which ended up with a burned wing that needed to be replaced in full, the other was fortunately contained to the wheel spats only. Reason? Wrong feet position during taxi. In the DR400 it is extremely easy to place your feet too high on the pedals, resulting in constant brake activation. When after the incident the club pulled the data from the engine (DR400-135CDI with the Thielert/Centurion engines and full FADEC) they found not just that incident, but actually several occasions where people were inadvertently riding the brakes and needing, in some cases, as much as 50% power to get the aircraft moving from standstill. This has now also been added to the checkout and club check lists.

[foxmoth]

nor why a hard runway should make any difference
On a grass runway the bumpy surface will cause a lot of wear and stress on the nosegear if you do not take the weight off with some up elevator, how much elevator depends on the aircraft, on a smooth runway you will get away without stick back because of the smooth surface, still a poor technique though.

[Jan Olieslagers]

But is "getting away" sufficient? It stays well apart from "as high as possible as soon as possible, in safety (i.e. without risking stall)" which I still believe in.
The rest of your phrase is a bit confusing to me, I'm afraid, do you mean that lifting the nose as much as possible will increase wear and stress on the nosegear? That is hard to imagine for poor little me.

[A and C]

As Backpacker says the final inch or so of nose gear extension results in the nose gear centering lock engaging and locking the nose gear steering in the Neutral position. If this should happen at low speed the aircraft is almost imposable to steer as there is not enough rudder authority to overcome a well planted and unsteerable nose wheel.

This situation is a result of a lack of or bad maintenance practices and will not occor in a well maintained aircraft.

Unlike American aircraft Robin landing gear legs require a measured amount of oil, American practice is usually to fill the compressed leg with oil and then compressed air, the Robin leg requires to be overfilled ( in American terms ). This oil quantity is critical along with the correct air pressure to obtain the correct rising spring rate when the leg is in service.

I have seen nose legs over inflated presumably to increase the propellor clearance and main legs under inflated ( for a softer ride?) but both of these defects are an accident going some place to happen as premature nose gear centering lock engagement is likely to occor.

The later DR400 maintenance manuals offer very clear guidance on the servicing of landing gear legs ( the first edition of the manual was a less than understandable translation from the French language ).
The maintenance data is different for all the DR400 variants and should be strictly adhered to to obtain the correct Spring rate for that DR400 variant, of this is not done there is a danger of the nose gear steering locking.

The technique I described in a post above is intended to keep some of the weight off the nose gear but not to have it pointed skywards, initially on the takeoff run the thrust vector ( the only vector at the start of the takeoff ) is trying to dig the nose gear into the ground and full up elevator counters this and keeps the aircraft in a level attitude, as the aircraft gathers speed and elevator authority increases the stick should be moved forward towards slightly aft of neutral to maintain this attitude until about 50 KTS when a smooth rotation should start aiming to lift the main wheels off the ground at 55 to 60 KTS.

Keeping the stick hard back throughout the take off run is going to end in tears, the aircraft is more than capable of getting off the ground well below normal stalling speed and therefore without full control authority due to ground effect...........it is an interesting flight regime that is best left untried by all but test pilots.

[foxmoth]

But is "getting away" sufficient? It stays well apart from "as high as possible as soon as possible, in safety (i.e. without risking stall)" which I still believe in.
The rest of your phrase is a bit confusing to me, I'm afraid, do you mean that lifting the nose as much as possible will increase wear and stress on the nosegear? That is hard to imagine for poor little me.

No, getting away with it is not sufficient which is why I put that it is still poor technique, edited the rest so that hopefully it makes more sense to you.

[9 lives]

I very much support A & C's post above. A well maintained aircraft should not require "special" pilot technique during runway operations to optimize nosewheel steering. It you have difficulty steering the plane on the runway, while holding the nosewheel light, refer the aircraft to maintenance. I cannot think of a GA aircraft, for which forcing the nosewheel down to steer while on the runway should be required.

And then hope the maintenance people find something wrong, or it's your technique!

[Vilters]

The simple rule that always works is: Unload the small wheel.
For a taildragger, that is stick forward to unload the tailwheel.

For a trike, that is stick backwards to unload the nose wheel.

Then as airspeed increases, and you get "feel" in stick and rudder pedals that the air is "biting", then you can start to "fly" the aircraft to take of.

Most think that "flying" starts when the wheels leave the ground and stops when the wheels touch the ground.

That is why so many "modern" pilots get in trouble when they convert to taildraggers.

[indyaachen]

Oh my .... the feel is so different when you need to transfer your skills from a 900m asphalt runway to ~500m grass runway.
Holding back the control column was an easy modification to the habit, but the "light feel" of nose up and moving the control 'a bit' forward will take sometime getting used to. The difficult level goes one/two notch up as the control column is shaking on the grass runway :confused: For today's lesson I had the Grob 115. :confused::confused: Even though Robin is fun to fly, I think I am going to stay with Grob.

[TheEnthusiast]

Hi all,
I've recently changed my ATO and now will be trained either Grob or Robin. I already had a flight in Robin, where the instructor showed me something that I've not done before: holding the stick in back position form the start on the runway.
I have about 20 hours on Robins post-PPL (I learnt in Cessna 152) and the stick back instruction surprised me at first too...but all experienced Robin instructors say it: stick full back always whilst taxing and at the beginning of the take-off roll, easing as speed builds to avoid rotating too early. As well as taking load off the nosewheel, the DR400/180 in particular has only a small clearance between propeller and the ground, so you need to do everything possible to avoid a propeller strike, particularly on grass runways where a bump in the wrong direction could be very bad news. I didn't fully believe this until someone way more experienced than me did exactly that... a prop strike in a DR400/180 on a grass strip...now I'm absolutely paranoid about remembering to keep that stick back!!...

[Brad2523]

On the robin hr200 I was always taught that stick all the way back on take off for soft field, then as you leave the ground nose forward to gain your 70kts and climb out as normal. But just gets you off the ground that bit faster and stops the nose wheel acting like a plough on soft grass.

[A and C]

The symptoms you write about have all the signs of mis -servicing of the landing gear shock struts, the likely reason for the inadequate propeller clearance is an insufficient amount of oil in the nose shock strut, the result is the spring rate fails to rise fast enough to maintain the propeller clearance. ( with the added safety if all the air is lost and a hydrulic lock stopping the leg from fully compressing to maintain a minimum safe clearance )

Robin would not build an aircraft that did not have enough propellor clearance, unfortunately they can't legislate for the idiots who don't read the maintenance manual and fail to service the landing gear in accordance with the published data.