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Diff brakes and side-slip  This thread currently has 266 views. Print
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Antoni
July 9, 2018, 12:12pm Report to Moderator

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I've never been very good at navigation. In 20 years it has caused some 'tightening of the sphincter' but never a failure so far.

From the air the UK is a busy patchwork quilt [/cliche] - tiny irregular areas of differing shades of green. For most people navigation is not difficult because of the many major ground features. With GPS as back-up I go by line on the map, marking across the line with stopwatch minutes when overflying certain obvious points. Often only two or three minutes apart because I know my limitations. On Sunday I hadn't seen my destination at all but from the numbers it should have been directly below me. Great thing about the Minimax is you only have to roll it onto its ear to see below you. Destination was indeed directly below. Good job I was at 2000 feet and therefore not a hazard to the busy fly-in at Brookfield Farm. From then on, easy dead-side descent into circuit and land over the fishing lakes. It's normal in the UK to avoid too big a circuit because of all the stud farms, falcon hatcheries, 'aviation anti's' and some bugger who might cause a stink for the strip that you don't know about.

Multiple tiny fishing lakes all the way to 300 feet before threshold are very daunting. Keep plenty of energy on in case of engine failure. Then just scythe it down with a side-slip. My usual side-slip direction produced an unexpected picture. I tried it the other way - much better - but only after getting the inputs wrong and momentarily getting a really bad picture. My brain took no part in proceedings - only the picture, my left hand, and feet. Reasonable landing but with full rudder deflection and some differential brake involved. At the sign-in point someone said 'We saw a Minimax coming in with a heavy cross-wind - this should be interesting..."

I hadn't even looked at the windsock - completely forgot ! ! ! Too busy with the nav the radio and the approach. It was about 12 straight across with a bit of tail.

On leaving the fly-in there was still some crosswind directly from the right but I thought it would be manageable. It was only barely so. Used full left rudder and full left band-brake to get off in a straight line.

Frequent side-slip practice and diff brakes saved the day - or at least saved embarrassment...

If you haven't tried *using* side-slip you should - it's automatic after a bit of practice - just look ahead at a distant mark, apply cross controls and try to hold the mark on the nose using either feet or stick, depending upon which turns out to be more powerful. In the case of the Minimax I apply rudder then correct and steer with the stick. It's another string to your bow when you need it.

Long time ago the first Minimax I bought did not have diff brakes. Again I was taking off with a crosswind from the right and little Minimax experience. I found that I could not prevent the yaw to the right or slow down enough to prevent collecting part of the hedge which ran adjacent to the strip. In desperation I applied enough left aileron to rub the left wingtip on the grass. Disaster averted.

If you are new to the type remember that if the prop turns clock-wise when seen from in front of the aircraft (Rotax two stroke) it will not like side-winds from its right because the swirl from the prop will clout the rudder on its right side - adding to the weathercock effect from the side-wind.

Why do we put ourselves through all this?
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Ricardo
July 10, 2018, 3:28am Report to Moderator

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Quoted from Antoni
...If you are new to the type remember that if the prop turns clock-wise when seen from in front of the aircraft (Rotax two stroke) it will not like side-winds from its right because the swirl from the prop will clout the rudder on its right side - adding to the weathercock effect from the side-wind.
...

It applies for take offs when the the prop blast is very strong, on landing there's little to none effect.
I've had 3 ground loops with my Minimax, the first two while learning how to handle the plane on fast taxi tests and the third , some years ago when I left the plane unattended  after a proper landing.
I've had few close calls also ,funny thing is all of them, but one, were coming from left side crosswinds. Just a coincidence.

Picture below is at take off, crosswind coming from the right, as you mentioned.  Watch trees far behind....Close call!



Attachment: wind_gust_9679.jpg
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mullacharjak
July 10, 2018, 11:00am Report to Moderator

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Full left rudder left brake in a  crosswind from the right.

Please explain if this is a standard control application.


KK
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Bill Metcalf
July 10, 2018, 3:34pm Report to Moderator

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If you are using the Flintstone-era band brakes, I would not suggest using them to effect control in any situation outside of helping initiate a slow turn while taxiing.
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Antoni
July 11, 2018, 8:46am Report to Moderator

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Quoted from Bill Metcalf
If you are using the Flintstone-era band brakes, I would not suggest using them to effect control in any situation outside of helping initiate a slow turn while taxiing.


Totally disagree.

One of the major advantages of the stone-age band brakes is that they are so gentle that even when fully applied in panic they will not nose you over if the stick is back.

They most definitely add to rudder authority. When you run out of rudder when landing .... or taking off, application of band-brake on the same side as your fully extended toe will help big style.

And one brake is powerful enough to do the turn-on-a sixpence party trick when lining up the aircraft to park at a fly-in.



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Antoni
July 11, 2018, 8:51am Report to Moderator

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Quoted from mullacharjak

Full left rudder left brake in a  crosswind from the right.

Please explain if this is a standard control application.


You should do whatever is needed in any situation using the tools you happen to have in your toolbag.

Best not to get into a situation where you need to use all of your tools.





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