Just starting out

[Biggles' Elder Brother - Moderator]

Hi,

 

well pretty well all models pull to the right on take off. Its a perfectly normal reaction to the torque from the accelerating engine.

 

The first thing you can do to help is be a little bit more progressive opening the throttle. When beginners first learn to take off they are often quite timid with the throttle and have to be encouraged to be more positive with it. But when they get a bit more confident they often go to the other extreme and open the throttle too quickly which provokes a torque reaction in the form of a swing to the right. Then they lose a bit of confidence, start worrying about take offs and seem to want to get them over as quickly as possible. The theory being "if I really run at it then it wont have a chance to get out of line"! So they slam the throttle open. But of course this just increases the swing even more!

 

Its a bit of a multi-phase thing this torque swing:

 

Phase 1: Initial reaction on just starting rolling. You should be holding a touch of up-elevator at this point, this pushes the tail down and so gives the tailwheel steering authority. At this low speed the rudder is doing very little to help you as there is almost no flow over it. So its basically the tailwheel that corrects, so you need down force on it - hence the touch of up elevator.

 

Phase 2: The model starts to build speed. This is the tricky bit. At some point here you take out the bit of up elevator. When? Ah well, that's the trick! At some point, as the speed builds (both the model's speed along the ground and the prop wash from the speeding up prop) the air flow increases and rudder becomes effective. Once that happens you're better with the tail wheel off the ground and steering her with the rudder just on the main wheels. You have to judge when that moment comes - its called experience!

 

Phase 3: Just before take off. At this point the fin becomes effective. Assuming you are taking off directly into wind the fin will now hold the model straight and you don't need to use the rudder any more (well for the time being anyway!) If you are not in line with the wind, and it is quite strong, you may notice the model suddenly "weathercocking" at this point into the wind. Note this isn't a swing - its more of a "dogleg" as the plane simply lines-up with the wind. Don't fight this unless you really have to - its the way an aeroplane flies! You can hold rudder against it but its not half going to complicate things for you, so at this stage - unless as I say for safety reasons you have no choice - I'd let the model have its head in this matter.

 

So, phase 1 its up elevator in and tailwheel steering, phase two its elevator nuetral tail up and rudder steering, phase three its basically no rudder the fin is directing matters squeeze a bit of up elevator and off she goes!

 

If you can practice along those lines and remember to be "decisive but progressive" with the throttle then you should start seeing some straighter takeoffs soon

 

BEB

Edited By Biggles' Elder Brother - Moderator on 25/09/2011 21:32:37

[flyeruk]

Thanks very much for your reply. I am a bit confused now. When reading various threads,i keep seeing people say the plane naturally veers to the left. Thats why i thought something was not set up correctly. Im not having a problem with the take off run,just thought it was supposed to pull left so right rudder was needed rather than left?Sorry for my confusion.

[Biggles' Elder Brother - Moderator]

Opps! Too busy this evening I'm afraid and on "auto-pilot!! You're correct! The model will naturally veer left. The rest of the advice holds!

 

So its going right? Mmmm, well possible causes of that:

 

1. Too much right thrust in. Most models have the engine slightly offset to the right to counteract the torque reaction. If this is overdone it can result in the model swinging right. You said the firewall has been out - could it have been re-inserted with a slight right bias? Its easy done and only a relatively slight error is necessary to cause problems. This can be dealt with by the methods I've described above.

 

2. Undercarriage out of true. Have you tried rolling it along a tarmac or similar surface to see if there is any bias there?

 

BEB

[flyeruk]

It rolls straight when rolled along a flat surface so dont thiink it would be that. The fire wall was loose at the top edge so didnt actually come right out,i just epoxied it back in place.I did purchase this plane second hand so possably there was a problem before i had it.

Its not really a problem as i have got used to it now but just wondered why it was happening.

I intend flying the pulse at the weekend so will have to just be aware that it will pull the other way.I am still doing my take offs standing behind the plane.

[Biggles' Elder Brother - Moderator]

You'll enjoy the Pulse its a cracking model. You're doing the right thing by taking your time with it, setting the throws gentle. Consider adding just a little exponential if you can to the ailerons and elevator - about 25% is plenty for a Pulse. It will help to "smooth" things out a bit.

 

Remember four things before the maiden:

 

1. Triple check that all the control surfaces are secure and move in the direction they are suppose to - its very easy even for experienced pilots to get this wrong - you'd be surprised!

 

2. Be confident in your engine. Does it throttle well to max revs - does it idle steadily - does it pick up from idle cleanly? Is the mixture right - hold it vertical at full revs for 20 secs - does it run steady? If it "fades" its too lean. If you have less than 100% confidence in your engine - sort it before trying to fly the model.

 

3. Do a range check. Very important.

 

4. Check, and check again, that the CoG is in the right position. If there is a range given - I've had a Pulse but it was a while ago so I can't remember! - have it towards the front of the range. Better a little nose heavy that even the slightest amount tail heavy!

 

The overriding impression the Pulse will give you at first is that "it goes exactly where its pointed"! That is to say that unlike the TT it won't tend to "right itself" so much. Watch out for this in the first few turns. You're probably used to holding a bit of aileron in through-out the turn - you won't need to do this with the Pulse - a bit on entry, then once you have the angle of bank you want, ease off the ailerons and it will more or less stay banked and, with a bit of up elevator held in, it will turn at a constant height for you. To come out of the turn you'll need to actually use a bit of opposite aileron to unbank it! Its easy and second nature once you get used to it - but it can catch newcomers from a trainer out at first.

 

Remember to keep the nose slightly down on approach to keep the flying speed reasonable and then flair just before touch down.

 

Best of luck with the maiden. The Pulse is very forgiving and with the experience you have on the TT you should be fine.

 

BEB

[flyeruk]

Thank you very much BEB. I think the v trainer helped me, as there is no dihedral at all with the aileron wing. I found the TT a lot easier to fly than the V trainer. Also,my time flying helis taught me to counter every move with an opposite movement.

Really looking forward to flying the pulse. The weather is looking good for the weekend and i will be at the field by 8.30 saturday morning. I think i will fly the V Trainer for my first flight,then fly the pulse.

Thanks again for your very detailed posts,i really appreciate the encouragement and help.

I will let you know how it goes on saturday.

 

[flyeruk]

I have had a bit of a mixed weekend to say the least. Went to the field early saturday morning. First flight was the V Trainer. Good 15 minute flight. Next up was my first flight with the Pulse. Started her up,slowly increased the throttle,tail came up,and up she went. Nice straight climb to around 100 ft,turned to the right,no problems at all. completed a couple of circuits and did a few practice landing approaches. Every one is right about being a floater but did not have a problem with the landing apart from a small bounce. I continued to fly the pulse for another 4 flights,really love this plane,so precise and really does go where you point it.

Sunday morning,up nice and early,up the field by 8.30 again. First flight was with my V Trainer. Then it was time again for the Pulse. Nice fast takeoff,again,climbed to around 100 ft and just flew around getting comfortable with the plane. This was followed with another flight,then,disaster.I was doing a final turn to line up for a landing,banked over into the turn and just lost it for a second. Got disorientated and in she went.. Damage was a broken prop and the fuse was snapped in half. Wings and tail unharmed. I was annoyed with my self for a few minutes and then thought,thats the name of the game. I feel i have done really well up to this point and just put it down to the learning process. I picked up the pieces,took them to the car and got out mt TT Trainer. Got her straight up in the air and flew 3 flights.

I would post a pic of the pulse but not sure how to post a picture. I dont know if i should try and repair the damage or just buy another fuse. I really want to get this plane back in the air as she is such a nice aircraft and i think i could go far with her.

[Biggles' Elder Brother - Moderator]

Oh dear - really sorry to hear about the prang with the Pulse - and you were obviously doing really well. But as you say, its the name of the game. I don't want to depress you but it won't be the last time you "stuff one in" - we've all done it, and most of us many more times than we would like to admit!

 

You did absolutely the right thing - dust yourself off and get back in the saddle!

 

I would think that unless its in a hundred little bits the fuselage is well worth reparing - you'll find a new one will cost you nearly as much as a complete new model! Put it to one side for a couple of days then take it out and have good look in the cold light of day. You'd be amazed what can be fixed and as a mate of mine often says "many of 'em fly better after a repair or two!"

 

BEB

[Chris Bott - Moderator]

Very well done for getting this far flyeruk. As BEB says, it happens to everyone. It's amazing how many people crash in the first few flights after passing their A test.

 

There are tutorials on here somewhere about posting pictures.

Basically they have to be either uploaded to the "my photos" section on here or uploaded to some other on line photo website. Once on line, press the photo button in the row of buttons just above the box you type your post in, find a way to select your photo and Bob's yr uncle.

 

If we can help in any way with the repair, just ask

[flyeruk]

I have taken my pulse fuse down to see Stan Yeo at Phoenix Models in Newton Abbot. He was very helpful and had a good look at the airframe. He has shown me what i need to do to repair it and has said its well worth while spending the time to piece it back together. Can i just take this opportunity to say thanks to Stan and can certainly recommended a visit to his shop or web site.I intend to get to work on it within the next few weeks.

I have decided in the meantime to get the Irvine trainer in the air.I have very nearly set it up but have a couple of questions regarding this model. I have also converted this model to a tail dragger for the same reasons that i converted the TT. i have read that this model tends to be nose heavy. Now i dont know if its because i have converted it to a tail dragger but to get the CoG correct,i have had to add 240 grams of weight to the nose. The CoG is 85mm behind the leading edge of the wing. This just seems a hell of a lot of weight to get the balance right?

Also,the tank supplied with it is only an 8 once which seems a bit small. The TT tank is 12 ounce.I have got a os 40 la in the plane at the moment but was thinking of putting the Evolution 46nt engine from the pulse in it for a while. Would this be a good idea or not?

What i think i will do for the next few months is get as many flights in as i can with the trainers before going back to the pulse.

[Biggles' Elder Brother - Moderator]

Wow! That's a lot of lead in a trainer! Usually trainers balance pretty well right straight off. In adding the tailwheel you will have added extra weight right at the back - and you'd be surprised how an ounce or two there becomes 10 ounces in the nose - the tail is lot longer than the nose so exerts a much greater leverage!

 

What type of tailwheel have you used - is it one of those with a metal fixing plate? Cos they are heavy!

 

An 8oz tank should be OK - but if you can fit a 10oz in without any trouble then go for it.

 

What's wrong with the 40LA? The 46 will give you more power - but the 40 is OK, and no effort required!

 

BEB

[flyeruk]

The tailwheel is just a plastic bracket and wire spring wheel affair,very light.Only reason i thougt about the 46 was the weight might have helped the balance. I have the 40 la in the TT and its fine.Do you think that amount of weight will not be too heavy?I was even thinking about just putting a tail skid on as i dont really think the tailwheel,which is fixed makes a lot of difference.

[flyeruk]

I did add a light ply plate at the back,under the tail wheel as well.

[Biggles' Elder Brother - Moderator]

Well 240g is an awful lot of lead - too much really! I've known a few scale models need that much - but never a trainer!

 

What about the main undercarrage? You must have moved that forward to make it a taildragger - have you changed it for something heavier?

 

The thing is, from what you describe - even allowing for the fact that you have put a bit more weight in the tail - I can't understand why it needs so much lead. Can you move the battery pack forward?

 

BEB

[David Davis]

I agree with BEB.

 

240 grammes is nearly 8.5 ozs in Christian measurements, according to my calculations. All ARTF 40 trainers I've ever come across, when fitted with a tricycle undercarriage, don't require any extra lead in the nose and the difference in weight between a ball-raced 46 and a plain bearing 40 is not enough to make a significant difference to the C of G on this type of model. Are you sure that the balance point should be 85mm from the leading edge? Extra weight will certainly make it fly a bit faster which is not what is required on a trainer.

 

I'd be inclined to take it down to Stan Yeo or some other knowledgeable enthusiast to get their opinion.

 

 

[flyeruk]

I had a word with Stan today,he also thought it was a bit much regarding the weight and suggested checking the CoG with half a tank. Being an eight ounce tank,that would give me half the weight. I have been doing a bit of research on various forums and found a couple of people who had the same problem with the Tutor. One person said he needed 300 grams to get it right. I am going to have another look tonight and see what i can come up with.

Regarding the tail wheel verses the skid,any opinions?

[fly boy3]

Hi flyeruk. IMHO, I don't think the amount of difference between a skid, and and a plastic type tail wheel will make hardly any differance with that amount of lead in the front, as BEB and David point out it is a lot of lead. Can you explain what you had to do to convert it to a tail dragger, if you just removed the nose wheel, did the model just fall forward or backwards.?. Cheers  ps can you find out what engine was recommended for the tutor. I put an OS 40 on my grandsons Arising Star,  and had to put a little lead up front. The A.S. was built for a 46 motor, there was the differance.  Cheers

Edited By fly boy3 on 06/10/2011 22:16:05

[flyeruk]

To covert it to a tail dragger,i removed the nose wheel assembly and original main landing struts. I replaced the struts with a stronger set from Perkins,moving them forward to just under the leading edge. I reinforced the floor inside the fuse with ply and triangular balsa fillets and added a ply plate to the underside of the fuse where the new landing gear fixes.At the rear,i again added a ply plate for the tail wheel to screw too. I converted my TT Trainer the same way and it flys very well indeed. Only difference is the TT only needed 20grams to balance it.

[fly boy3]

Hi Flyeruk, If you put "Tutor 40" into the search box top left of page there is a lot of info that might be use full. you are correct, CoG is 85mm from LE.Where is the battery located at the moment. Is it possible to put it under the tank. ? Cheers

[flyeruk]

The battery at the moment is just behind the fuel tank.Its a HI-energy 2200 4 cell pack. Im not sure what it weighs. I will give it a try tomorrow and see what its like.

Just found out it weighs 116 grams. 

Edited By flyeruk on 06/10/2011 22:46:39

[fly boy3]

Any chance of it going underneath your fuel tank ? If you can manage that, and try to move the engine forward, you may then be able to remove most ,if not all of the church roof.

[flyeruk]

I will give it a try tomorrow. I think i could get it under the tank. Just read one of the Tutor threads and see somebody else had to put 200grams up front. Bit concerned about moving the engine forward,would that not change the thrust angle?

[fly boy3]

Not at all. If you have some room on the engine mount to enable the engine to move forward I would give it a go.No need to drill holes etc just let the engine rest in a more forward position with lead removed and try CoG again. I have years ago, fitted a longer 4stroke engine mount to allow engine to be so positioned that CoG was correct. Trainers should be able to fly more slowly than low wingers, aerobats etc to allow the pupil a bit more time to adjust, With extra weight, she will still fly well, but not quite as the designer would have liked,as long as the CoG is correct. Cheers

Edited By fly boy3 on 06/10/2011 23:20:41

[flyeruk]

Many thanks,i will let you know how it goes.

[Steve Hargreaves - Moderator]

Whatever the outcome don't be tempted to fly it with the CoG too far rearwards....its better to be a bit heavy than to have a rearwards CoG.

 

A trainer will probably be fairly forgiving of CoG position but remember the old adage...."CoG too far forwards....flies badly. CoG too far backwards......flies once"

 

Personally I think putting the 46 in it will be good idea.....the extra weight will help &you do have a throttle so can reduce the power. Having plenty of grunt up front will allow you to start licking the sticky bit of the performance envelope....getting those sticks in the corners can do wonders for your confidence (as well as being great fun)..