Richardfast

My Feedback: (15)

I am just starting to practice (as spring has finally arrived in Michigan) pattern maneuvers and I was wondering about proper throttle management for the down side of circular maneuvers ( split S, reverse cuban, inside loops, etc.). Do you keep the same throttle setting throughout the maneuver ( my plane, a Sig Somethin Extra w/ST40 can pull through all Sportsman maneuvers at 1/2 throttle) or throttle down on the downside? The maneuver looks to come out the same, but obviously gets through the maneuver faster if you don't cut the power back over the top. The problem with cutting power is I have to find the right power setting to return to upon completion of the maneuver. If I don't get it just right I have to reset the trim. All of this is tough for a thick thumbed beginner.

patternrules

My Feedback: (6)

One of the things your trying to achieve is constant speed, so basically you would have a throttle position at level flight, and add power for up lines adn reduce power on down lines.
There are things that could cause your trim change not sure what but if you have a computer radio you could do a mix between the throttle and the elevator.

Steve Maxwell

PatternFlyer

My Feedback: (182)

Welcome aboard to Pattern!!

I just started to fly Intermediate at the end of last season after skipping nearly two years.

I always try to keep the speed constant and was taught to do so for smoothness.

In my case, the plane is a little heavy in overall, so I use full throttle during vertical up and reduce the throttle during down.

If you keep the throttle at the same level during a loop, going up is fine, but the plane will increase speed when it come down and also will be sensitive on elevator compared to up flight.

As long as your manuevers are done smooth & round at near constant speed, you won't have problem, but I would recommend to throttle down on downside.

When fly loop, I do following way of throttle.
Level flight is mostly half throttle, when entering the loop, I start to increast throttle smooth so that the plane does not suddenly change its speed.

When the plane is up at the top of the loop I cut the throttle to keep it's speed.

After passing 3/4 of loop, I begin to add throttle back to half throttle exiting to level flight.

This is just my case with one of my plane.
In your case, your throttle setting will be different since you stated that the plane will do manuevers at half throttle.

How large are your manuevers?
I tend to make manuevers too large for my plane, doing this actually show all those mistakes during manuever.

If you make a manuever large, be sure that you will stay in box.
Also, do not make those manuevers too small, if this becomes your habit, you will have hard time adjusting and flying a larger size plane later.

Try to have a coach (pattern pilot who knows the manuevers described in the judging guide) if you don't.

I don't have a coach anymore. I am the only pattern guy in my area, so I have to practice a lot more and ask my friends at the field to look throught my manuevers and tell me how they were done. It still helps a lot.

Also, I don't understand exactly what you mean by "reset the trim".
If you are talking about the trims on each control surfaces, you need to find out the correct trim setting.
Most of our planes do not need trim changes once set correctly.

Try check out the trim-sheet at NSRCA. CG is always the most important thing, so it takes a while to setup a plane correctly.

http://nsrca.org

All you need is practice.
It shows at contests if you had lots of practice with correctly trimmed plane.

Hope this helps,

Sorry for the long post. I tend to go long most of time when I try to explain something.

Richardfast

My Feedback: (15)

Thank you for the advice on throttle management. Out to the practice field I go! Oh by the way, my new pattern plane has been ordered. I am going to fight the pattern look-alikes and go with a 67", 8 lb Extra 330S. I figure this will be fine for Sportsman and still give me a chance to go a little crazy once in awhile. Power will be an OS 1.20 FS w/pump.

3D Joy

WOW where have you found an 8 lbs 67" Extra 330S ? That sounds REALLY light for that size.

Anyway, I think you will still be able to perform all the maneuvers at half throttle !!

Richardfast

My Feedback: (15)

I apologize, that is a 10 lb, not 8 lb, 67" 330S! I am refering to the KMP Extra 330S.

gavoss

My Feedback: (16)

I'm just starting Pattern...again! One thing I learned from an advanced pilot, years ago was throttle set up.

To help keep the manuevers constant speed he had programmed in a long "flat spot" in the throttle curve in the middle of the range. This way you had to have the throttle stick within a few clicks of full before you got full throttle. This left you with lot's of throttle stick movement with little change in rpm, but only in the middle of the throw.

With a light plane you mentioned, this might work out really well for you. gv

KenChoo

I agree with what the others have said about your maneuver dictating your throttle management - to achieve constant speed and preserve maneuver shape. But I've found that with a lot of planes, if you cut throttle down to idle right at the top of the loop segment, the vertical-down segment tends to be too steep. For that reason, most pilots hold in a bit of throttle until they're about 30-40 degrees nose down, before cutting throttle. This helps to round out the loop. As for gaining speed on the downside, (since you're keeping throttle on a bit longer), that's one reason why pattern pilots like the large props and 4 strokes and also the large body fuselages...for their braking ability on the downline, to preserve that oh so valuable constant speed...

Hope this sheds a bit of light..

Cheers,
Ken

jamesjoneill

Ken's description of leaving the throttle on past the top of a loop is spot on. It does sound though that your thrust line is well off - you need a plane which flies straight and level a 1/4 throttle as well as full throttle. If you trim the plane to fly level at full throttle and throttling back then causes the plane to dive markedly, you need more down thrust. This is really the only way to correct the problem, mixing it out on the Tx will only cure the problem half of the time.

I would 100% recommend you sort this out, then when you can use the throttle properly to adjust for wind speed etc. as well and you won;t be fighting the plane the whole time.

James

Anthony-RCU

My Feedback: (2)

Lots of good comments here. Use just enough throttle to get throught the maneuver cleanly. Last year I was flying a lot of lines too slowly and the plane would wobble and show every correction. A little more power and every thing was smoother. Too much power and no time between maneuvers for a smooth straight line or corrections.

walshy

Your extra should work ok for pattern, I have been experimenting with a 66 inch extra 300 s 4.7 kilo (10.4 Pound) with OS 160 FX 18x10 prop. It flys the expert shedule very well, loads of power, half throttle on the straight and level, 3/4 to full throttle for the up lines and ease the power off past the top of the loops and ease it on again begining on the last 1/4 so that you are back to your original throttle setting at the end of the manouver.the only trouble with the scale planes is little wobbles after rudder applications such as piont rolls or line corrections because they are so short in length. You have to be very very smooth with rudder application and release. A proper pattern model is easier to fly and is less likely to exhibit roll or pitch coupling. It is great to see a scale model at a pattern event for a change I think.

poorbs

My Feedback: (3)

One thing to look for in throttle management is whether or not your rpm level is really that much lower when the throttle stick is half way up. Most 2 cycle engines I 've known are at almost top rpm when the stick is half way up, so on my Webra Bully 1.20 I go to minus 100% expo on the throttle and I find a much more linear control of rpm. Another example is when I was flying a YS .61 LSRE, when the throttle stick was all the way down and idle trim all the way up, I was getting 6000 rpm. When I advanced the throttle stick to full, I was at 9700 rpm - not much difference considering it was my entire range of throttle control.

If you look at the opening in the carb as you advance the throttle, you should notice that it doesn't have to be all the way open to get near max rpm. Going to minus expo gives much more control.