Peter Jenkins

Hi PatMc I did read the text before you deleted it and I hpld my hand up for getting my recommendation the wrong way round. So, for a low wing aircraft,ike the Ruckus, an alternative to applying more down thrust is to increase the wing incidence. This would require the TE to be packed. For the same flying speed, you would need more down elevator trim to reach the same angle of attack as before i.e. the aircraft would be flying more nose down than before and hence more down thrust. Sorry for missing your point first time. Nigel Heather - please note the above.

Well PatMc Motor down/up thrust is set against a fuselage datum. So is incidence. If you reduce incidence it has the same effect as reducing motor down thrust or increasing up thrust and vice versa. If you disagree with that then draw the picture out and you will see the relationship between the two. To be strict about this, I should say for the same airspeed you will need to generate the same lift force for balanced flight. Reducing incidence means that for the same lift force at the same airspeed your wing needs to adopt the same angle of attack as before to generate the lift to balance the weight. So, the fuselage datum line will have to be tipped nose up and we do that by using some elevator up trim. Now if you look at the motor thrust line which is tied to the fuselage datum that has been pitched up .i.e. the up thrust has effectively been increased slightly compared with where it had been.

I completely understand Chris but as an advanced driver your observation should be much better than average. All the examiners are ex Police Class 1 Drivers. I suspect that the drivers to whom you refer would pull out with indicating without seeing you anyway. The point about advanced driving is that you are given a one hour test which covers all sorts of roads by an expert who judges whether you are up to the award or not. I'm sure they fail quite a few but I don't know. Many drivers have the view that by putting their indicator on that gives them the right to move out either to overtake or turn across a road but they haven't seen the traffic that is fast approaching. I'm talking about observation and not just a brief glance or a check after they have moved and often before they have made an indication and usually without looking first.

Having done the IAM test many years ago, the book says that rather than just indicating think about who you are intending to warn of your intentions. If there is no one who will benefit from seeing you indicate, then don't. As an example, if you are turning right and there is no one to warn then don't indicate. If, however, you are going to overtake someone and there is no one else on the road, the person being overtaken deserves to know that is your intention so indicate in this case. I never saw written down what Leccy was told. Perhaps he was doing his own thing in his instruction. I see plenty of people today who seem to think everyone knows where they are going so there is no need to signal - that, of course, is a different issue!

The two posts above is why I wrote a book entitled "Model Aircraft Precision Aerobatics". The B test consists of a majority.of precision aerobatic msnowuvres e.g. loop, outside loop, rolls, stall turn and spin. Many going after either the B or just to improve their aerobatics have found, in the absence of an experiencex instructor, the book provides the information on setting up your model and flying techniques that are needed for the B as well as lifting readers' views of what they could achieve by stringing manoeuvres together to perform mini-schedules and even to fly the entry aerobatic schedule. Even if the reader has no intention of entering a competition they can learn how to perform better aerobatics and set up their aircraft to perform better than they thought possible. The book is available from me (PM me iif you'd like to buy one £22 inc 1st class post in the UK) or buy from Amazon at £29.82, plus shipping, for a paperback or £8.99 for an e-book.

Just read through my posts and it is actually GG's post that introduces the tail plane incidence to the motor/wing incidence issue. So, I am not wrong in what I said as at no stage did I bring motor down thrust, wing and tail incidence together. Ergo, I'm not wrong. GG has introduced tail plane incidence where I didn't. Hope that clarifies matters.

In what way PatMc?

Just to manage your expectation of.an F3A aircraft, they do not plug together out of the box. There is a lot of work needed to get them into the air when the fun of trimming then starts. Quite often, there are no instructions either! So, I quite agree with Nigel's expectations of a modern mass produced product in that it should fly better than he has experienced but CG position does majorly affect the way the aircraft flies together with control throws being set to avoid twitchiness.

They do GG and some have adjustable tail planes that that' just to set the elevator flush with the tail plane once you have completed trimming. Remember that we are talking about a balance of forces that are generated by the motor, wing lift and tail lift or more normally negative lift or a downward force. Once you get all those sorted out then the aircraft behaves as it should. Obviously, good design should mean that these factors are close to being correct so we, the user, only need to tweak them a little bit. But, I guess "Friday afternoon" examples exist and Nigel might have one! The relationship between the TP and wing is much debated and is called decalage. When you have an elevator involved, it doesn't matter if it's out by a degree or so as the elevator trim takes care of that. Making adjustments so that the aircraft will travel vertically upwards, hands off, is where playing with down/up thrust and wing incidence comes into it. In a vertical upline, the wing should not be producing lift but the tail plane will still be producing the balancing down force to balance the nose down pitch of the wing assuming the CG is in front of the centre of pressure i.e. a stable situation and the resolved motor up/down thrust. On my current aircraft, the TP was fixed so you just carried whatever elevator trim was needed and zeroed out the servo arm to its mid position by adjusting the linkage. The easy way to do that is to use a turnbuckle pushrod as that gives infinite variation. Of course, we're not talking a large amount of elevator deflection here unlike that on my Stampe where a good deal of down elevator is required for S&L flying. What that needed was a TP mounted with more positive incidence rather than the 0 deg has been designed into it. As I say, it's all a matter of balancing the forces acting on your model so that changes in motor thrust don't produce significant up or down pitch when the motor power is altered. That having been said, I can remember being checked out on a Cessna 172 and being told to set up a full flap landing and then to overshoot. The nose up pitch on application of full power was quite interesting! The check out pilot told me that there had been the odd fatality when a lightly built female pilot was flying the aircraft and was unaware of this characteristic and didn't have the strength to push the control yoke forwards to prevent a stall. They then put in electric trim with a trim switch on the control yoke! Many full size aircraft do have such characteristics but we don't need to put up with them in models as we can design them out.

Incidence and thrust line are two sides of the same coin. I used an increase in incidence as I couldn't use more down thrust on my F3A aerobatic machine. It works fine by the way. Cured a pitch to canopy on a vertical up line.

Sorry Stuart Z you are incorrect in your statement. I confused the Ruckus with the Riot. For low wing aircraft to reduce incidence, which is what I was trying to suggest to Nigel, you do need to pack the LE. If you pack the TE for a low winger you will increase the incidence which is not what Nigel wants. Although, by the sound of his last post it's all academic anyway!

Sorry was confusing it with the Riot! Yes, the LE should be packed to reduce the incidence.

It's telling you to add more downthrust. Or, try packing the trailing edge of the wing to reduce the incidence. It is effectively the same as adding more downthrust. A combination of the two should cure the problem of ballooning when adding power. It may look odd but keep going till the problem is solved.

Finally made it out to the patch to test the Flight Coach board a fellow aerobatic pilot had built for me. As ever, our Chairman had left the patch looking like a bowling green! About 5 pilots had been there in the morning but when I got there at 4.30 I had the patch to myself. As you can see from the photo below, the approach heading west requires a fairly close conversation with a large tree. There used to be trees this size all along the edge till the farmer was persuaded to let us cut them down and he used them for firewood! The aircraft I'm flying is an Oxai Citrin. It is, IMHO, the prettiest F3A biplane I've ever seen and it flies really well. Far better than I can fly it! This was borne out by the flight paths I reviewed for the 3 flights I flew. More practice needed or rather fix the errors that Flight Coach has shown. That might take some doing but at least there is an independent review of what I actually flew.

Yes, natural aptitude helps but practice is a great leveller! Those who find it difficult to progress are usually those who for what ever reason, cannot practice regularly. What also doesn't help in the early stages, post being signed off solo, is to have a large number of models and fly them all equally badly on every session. While practicing with the same model will improve your flying skills a lot faster than having to cope with multiple models with different flying characteristics, there is also the issue of practising the right thing.

I would forget the flaps Toto if everything else works. You don't need flaps at your stage of flying. Go and fly the Tasman at your other club using the buddy lead and forget about the flaps.

I would say that there is a fairing as you can see one rivitted on plugging the gap between the wing and the fuselage. It's certainly not anything like as big and the wing to fuselage join looks close to 90 degs - but there is still a fairing.

I thknk Robin was referring to the er Robin being an excellent replica. On the Corsair, the bent wing was intended to provide clearance for the large diameter prop without resorting to a long u/c leg. That gave the opportunity to attach the root at 90 deg to the fuselage but it stll had a fairing though not as large as usual.

Thanks Futura57. It has only been possible to publish such books as a result of the growth of self publishing facilities. I think if you are really interested in sharing your expertise in either print or e-books now is the time when you can do so without having to make much or any financial input to get the ball rolling. Peter

Just to let you know, the Advanced Precision Aerobatics book has received a grading of 4.6 out of 5 on Amazon. A number of typos, pointed out by some readers, have now been fixed. The book is available from most Amazon stores around the world. If you have difficulty getting one, please PM me and I'll get a price for posting one to you from the UK. For UK buyers, the link to the book is here. The Amazon price in the UK is £25.99 plus shipping but free for Prime members. I can provide the book for £20 including 1st class post to a UK address. I can let you have a postage price for any other geography if you want to buy a copy from me.

Nigel and others who are interested in this topic It doesn't matter what the instructions say is how you should set up your aircraft. Yes, it's a good starting point. However, there are manufacturing tolerances that effect things. The only thing that matters is what the aircraft flies like. I've lost count of the time when pilots have told me that they have set the aircraft up exactly as stated in the instructions but it still doesn't fly right. The answer is to apply the following process: get the CG in the correct position for the aircraft. That is, when you roll the aircraft inverted, at height, or fly up a 45 deg climb and then roll inverted (at least you are flying away from the ground to begin with) see if the aircraft pitches to the canopy rapidly. If it does, just roll level and then land and move the CG aft a little bit and go and go and test it again. When the aircraft only requires a small amount of down elevator to fly level inverted you have arrived at a good CG position. fly past yourself in level flight at your normal throttle position - if that's at full throttle then that's an abnormal state!. Apply full power smoothly. If when you apply power there is no discernable pitch up or down but a gradual increase in speed and then a gradual climb that is a good place to be. If the aircraft pitches up quickly, add down thrust a washer at a time. If the aircraft pitches downwards, add up thrust a washer at a time. Keep adjusting till you reach the position where application of power does not result in a pitch up or down. For side thrust, from level flight, pull to the vertical while applying full power smoothly. If the aircraft yaws to the LEFT and some RIGHT sude thrust. If the aircraft veers to the RIGHT, add some LEFT side thrust. You have got it right when you can pull up to the vertical, or a loop for that matter, and the aircraft tracks straight. Those are the basic steps to ensuring that your aircraft is trimmed correctly and it may bear some or no relationship to what the instructions state. I've trimmed out a Wot 4 to fly in a way that the owner went away feeling very pleased as it felt like a completely different aircraft from the one he had started with which was not nice to fly. Of course, if you have a badly warped wing or a banana shaped fuselage then you have a problem as none of the traditional ways of trimming the aircraft will turn the aircraft into a delight to fly. The basic design might suffer from insufficiently sized tail surfaces as well making the aircraft less stable than you would want - small scale aircraft are like this hence the use of gyros to tame them. For a well trimmed aircraft there is no need for a gyro other than to help with the approach on a gusty wind day.

Well in that case, the symptoms you describe mean you need more down thrust and you have the means to do so.

Pitching up with throttle is due to too much up thrust and not a C of G issue. Many foamies don't seem to have a way of easily adjusting up or side thrust. What you really want is for the instantaneous application or removal of throttle not to cause an immediate pitch up or down. The aircraft will climb as speed and hence lift increases and vice versa but there shouldn't be an instantaneous response to throttle as that points to too much up or down thrust.

My Stampe also needs a lot of down elevator to gly level. I don't know if the full size Stampe has the same problem but otherwise I think the tail plane is set at the wrong angle. It probably needed the tail plane to be mounted with about a 2 deg incidence to decrease the amount of down elevator needed. Note there will still need to be a down force exerted by the TP in level flight.

It may look that way Leccy but they are indeed that way. The photo below shows a better view. I use the Hobby King shielded and polarised covers for my batteries and that's why the female connector on the bulb is bare - allows it to slide into the covered pin on the battery.