Peter Jenkins

Stearman, it matters not what brand or type of 2,4 GHz Rx you are using. They all have the same radio transmission features. Any 2.4 GHz Rx fitted with 2 aerials will require them to be spaced at 90 deg (orthogonal) to each other. All I can say is that the diagram to which I've pointed you, and to which Ron has commented on above, works for ANY 2.4 GHz Rx with 2 aerials. Some sets with the secondary Rx also had 2 aerials and the same applies to them. The analogy with 35 MHz is that you don't leave the aerial coiled up next to the RX regardless of which make or type of Rx it is. Hope that helps.

Gangster 75 from an unstarted kit, Super Tigre 90 and Hanno pipe. Not quite got the pipe on song but initial flights have proved that it is a great club aerobat.

Stearman, I just googled Flash 8 manuals and came up with this. If you look at page 15 it has an illustration of what is meant by aerials at 90 degrees. Briefly, as the 2.4 GHz wavelength is so much smaller than the 35 mHz one, the two aerials are designed to provide redundancy. As you may know, the worst case for an Rx aerial orientation is when it is pointing at the Tx and the best when it is at 90 deg to the Tx or parallel to the Tx aerial. As the aircraft flies around, one aerial is always going to be in a good receiving position - that's why there are two and sometimes more as well as a satellite Rx. The other point about these small aerials is that you want to keep them as straight as possible. Having them bent or kinked loses you range as you are affecting the effective length of the aerial exposed to the incoming Tx wave. I actually use snake outers glued to the fuselage side and then a spot of silicon where the Rx aerial enters the snake. Edited By Peter Jenkins on 21/02/2019 23:32:38

Rocker, I regret to say that you have still not managed to get your approach and landing speed down to the required level. Did you try landing at 50 feet up to see whether you ran out of elevator control before the model stalled? Did you check the CG position in the way I suggested? All of these are important points and it is worth persevering with trying to get the speed right for the approach and landing if for no other reason than you will undoubtedly come across this problem again sometime and you will then have a solution. Good luck with the FMS Hawk by the way.

Posted by Andrew Ray on 20/02/2019 09:15:54: Furthermore if landing fast and the aircraft pitches down that will kill the lift until the angle of attack is increased, the wing will only generate lift if the nose is raised, probably by the pilot pulling back on the elevator. This sounds more like a pilot induced oscillation and may be affected by c of g and elevator sensitivity. Excessive expo will not help in this situation. Edited By Andrew Ray on 20/02/2019 09:16:43 Andrew, I have to disagree. If you land a tricycle u/c aircraft too fast, it will bounce. Even jet fighters bounce as do airliners. We don't need to go to the extreme some pilots of jet fighters do of keeping the nose up to increase drag from the wing as our aircraft slow down pretty quickly in comparison, especially on grass. Light aircraft types like the Cessna 150 can also be bounced when landing too fast. If you have the speed right, and full size pilots have an advantage over model pilots as they have a read out of their airspeed, then the impact of landing generally knocks the speed back to below stalling speed - or else you use lift dumpers to kill the lift as most modern airliners do. With little lift from the wing, the weight takes over and pitches the aircraft nose down. I think it most likely that Rocker is trying to land with too much speed on his aircraft. It could then develop into a pilot induced oscillation as the bounce starts and you then push down elevator into another bounce now with up elevator to encourage the bounce etc. The best solution, if there is room on the runway, is to level the aircraft while adding a touch of power and make a second approach. If you don't have the room, or it just doesn't feel right, overshoot and have another go at landing - always assuming you have the fuel / battery capacity available.

Rocker, from your description it would seem that you are trying to land your Freewing Hawk too fast. The theory of landing a trike is that as soon as the mains touch, as they are behind the CG, the nose should pitch down reducing the wing angle of attack and cutting the lift. If you land too fast, the aerodynamic lift force wins over the pitch down force and the aircraft bounces. Many pilots are worried about stalling on approach and set too fast or steep an approach speed. When you flare the aircraft for landing the speed is too high to land and if you hold off till the speed decays to the right figure you can float the whole length of the runway. So, try landing at 50 ft and see how far the aircraft travels before it stalls. You should have enough height to recover safely. The other issue is CG position. If you have a forward CG then you may well run out of elevator authority when slowing down for landing and then the aircraft will bounce all over the place. To check for a good CG position, from level flight, pull up to a 45 degree climb and add enough power to maintain the speed. Then half roll to inverted and relax on the stick. If the nose pitches down immediately, try moving the CG aft a little bit and repeat the test. When the aircraft pitches down slowly that's a good CG position. You can do the same test by just rolling inverted when flying level but at a 45 deg climb you are at least going away from the ground even when the aircraft pitches nose down! With the CG in the right place, and the approach angle and speed correct, use the throttle to control the rate of descent and the elevator the speed that is the attitude of the aircraft. If she sinks, increase the throttle but keep the aircraft attitude constant with the elevator - don't use up elevator to pull up as you just end up porpoising all over the place. Similarly, if you are high, close the throttle - don't push down elevator to bring the aircraft downwards as you will just push up the airspeed. In summary, throttle controls height and elevator controls speed. Try that and see if it helps. Oh, even supposedly identical aircraft from the same manufacturer will feel different because of manufacturing tolerances but way different when the CG is in the wrong place. CG position is the single most powerful trimming tool we have - yet few people ever think about shifting it to correct aircraft characteristics. Good luck.

Well, today's experiments came up with the following: in it's current configuration (pipe length still too long) the 15x12 prop dropped rpm to 6,900. replaced it with the 14x10 and that produced 9,100 and gave a better vertical performance than the 14x12 the increased right thrust was, on the whole OK but there were times when the aircraft still pulled left in the vertical (I'm still pondering why that happened and it may be due to the difference in vertical speed and how the prop swirl is hitting the fin) the up/down thrust (instruction said set at 0 deg) is correct. Going from 1/2 power to full power produced no pitching until the speed had risen and then there was a slight climb which is to be expected. the vertical down line (this is a 0 -0 set up) produced a very slight pull to the canopy that can be cured by a touch of down mixed to closed throttle - it is so small I decided to leave it alone. whether the gap sealing or increased throws helped more on the ailerons is a moot point. However, at normal speed (1/2 throttle) the low rate roll is now too fast but on a vertical with a full roll the rate produces a relatively slow roll - something that getting the pipe to its optimum length might improve as currently the speed drops off quite a lot the elevator in low rates has too much deflection so I will turn this down the snap/flick roll isn't! This will need a very much greater aileron deflection to produced the required roll rate so I think we'll leave that as a manoeuvre that does not suit this set up. I think the big span wing, with the associated aerodynamic damping provided, is a major cause of this. Forgot the check the lateral wing balance when flying- a job for another day. the inverted spin is now better as both more elevator and more rudder movement have increased the rate of spin and it looks like a proper spin. Recovery remains almost immediate on centering the controls. Overall, the higher speed provided by the 14x10 prop was beneficial. The Gangster is now a very pleasant aeroplane to fly although there are still a few tweaks needed to get the best out of her. I will not cut another 1/2 inch off the manifold length and see whether that brings the pipe more into the power game. That may get the 14x12 prop revs up although it might make landing a tad more difficult with the slightly higher residual thrust at idle compared with the 14x10. With the 14x10, and an idle of 1,800 rpm, the aircraft floats a long way on round out. Only solution for calm days is to keep the approach as flat a possible and the speed down. As a comparison, I flew my 2 mtr Majestic (DLE 35RA power) to compare with the Gangster. Well, Mr Paysant Le Roux's design, and the power of the DLE, resulted in a comprehensive victory for the Majestic over the Gangster but then again, the Gangster was not designed to be a specialist aerobatic machine.

The one I use I had for almost 20 years and looks like the 2nd one on this Ripmax listing. Main thing to remember is to ensure that you point the tach through the prop towards some light. Pointing towards a dark background gives inaccurate readings. Also, make sure you select 2 or 3 blade before use. My one uses a 9 v battery that seems to go on for ever.

I've tried using an app but I don't think it's as accurate or repeatable (same thing really) as the Robart incidence meter. I think the other problem is that the phone edge can be difficult to align properly with the inevitable buttons sticking out of either side. Robart do a digital version as well but I have to say that I prefer the analogue version myself. Having said all that, unless you are going for great accuracy then using a less than perfect tool may be OK but don't expect too much.

Hi Nigel Yes, gap sealing was on my list of tweaks for the ailerons and that is now in place. The roll rate on my original low rates was very slow - the sort of rate that I'd set for doing very slow rolls. I've now upped all rates and reduced the expo on aileron and elevator. I've also zeroed the trim on aileron and elevator and adjusted the turnbuckle links so that the controls are where they were. Might need to give them another tweak after flying but have also reduced the trim steps back to 1 from 4 so that will help in fine tuning the trim. I've also added about 1/2 deg more to right thrust and this has had a very minor effect on the alignment of spinner to cowling but you have to look hard to spot this! I've replaced the 18 oz tank with a 12 oz one as I had used less that half a tank at the end of the 2nd flight. No point lugging around weight you don't need and I reckon I will only want about 12 to max 15 mins in flight. Ref KE behaviour, this is primarily down to CG position and the slipstream. My electric contra prop equipped F3A bird is virtually identical on either KE and will also snap left or right in exactly the same way. No torque effect or rotating slipstream to jigger things up. The static lateral balance was fine. I did not check it out in flight though. That will be tomorrow's task. I perform a vertical dive power off and then pull hard to level flight and look to see which wing ends up low. You need to do this at least 6 times to make sure you are getting a repeatable result of course. I'll post again after the next set of trimming flights.

Well, this morning I managed to fly the Gangster for the first time. Had 2 flights and the airframe came through it without any damage. Several points have emerged: The CG on the aft position quoted by Mick Reeves was almost spot on. It might be worth moving forward a smidge but that's being pernickerty. The engine set up appeared fine with no hesitation or heart stopping moments when overshooting. However, while the mixture is a tad on the rich side the power appeared adequate for normal sport flying but I need to get the pipe length shorted a tad more and possibly try a different prop. It has a 14x12 that pulls 8,600 max revs. I'm minded to try a 15x12 and according to the APC performance chart, if that pulls 8,000 revs it will provide about 2 lb more thrust. I'll see how it goes. The control throws are not right. Only full rates gave me the sort of feel I am looking for. That means the ailerons are too small and need more throw and ditto the elevator. The rudder appears OK at the moment but as I progress with trimming that might also need increased throws. I increased the size of both the elevator and rudder as I felt they were too narrow. Should have extended the ailerons while I was at it but thought they looked about right. A little more right thrust is required to get her to track straight vertically. Knife edge needs sorting as the aircraft pitches to the u/c one way and canopy the other. Spin, both upright and inverted is fine. I normally have a lot of expo on max rates, which I only use for spinning, so having to fly on max rates was uncomfortable with the amount of expo I'd put in. I will increase throws and re-set the low rates and see how that affects the handling. The handling is a tad odd. While I'm used to flying 2 mtr F3A airframes and didn't expect the Gangster to be in this league, it still felt slightly hesitant on occasions. Will have to see if this changes with the changes to the control throws. Otherwise, the aircraft rolls well, tried 4 sec slow rolls and they were pretty decent, and it will fly large loops but you do need to work at keeping it flying straight - more side thrust will help here. However, it's not an unlimited vertical aircraft and given the power to weight ratio I'm not surprised. Hope to make a few tweaks and fly it again shortly. Will report back on how the tweaks are doing.

Cymaz, you may already be aware of the GBRCAA Trim chart but if not, you will find it here. The point to remember is that CG position is the single most powerful trimming tool we have and any change in CG needs to be followed by the full trimming process. There is also a very powerful trimming tool by Bryan Hebert who has designed and produced for sale a number of 2 mtr F3A designs. He calls his trimming process, Triangulation Trimming. Many in the US and GB teams have used it to good effect. You can find it here. Good luck.

A fully charged 5 Cell NiMh has around 7.4 V I think. I have a 5 cell in another airframe and that has Futaba servos all round and has never caused a problem. JR servos, unless HV, should never be used with a 5 cell NiMh as they will burn out.

Does the manual give any geometry? Current aerobatic machines tend to carry engine at 0, wing at +0.5 and tail at 0. The old way was wing 0 tail 0 engine 0. I would be inclined to reduce the engine downthrust to -0.5 as I suspect you could have a marked pitch down on opening the throttle with the set up you have. Mind you, best is to try it first and then adjust down and side thrust. You may also need to play with wing incidence to get close to a vertical down and up line. Takes time to get these beasts dialled in but well worth the effort. I reckon on around 10 - 15 flights to get really close and after that there can still be more tweaking before it becomes just so! But, you always need to keep checking as structures twist with time, heat, humidity etc.

Oh Ron, that's tempting fate! 😭

Jonathan, the only thing I did when I decided to go the Life route was to swap out the JR NES591 servos I had installed for the ailerons. JR servos always warn not to exceed 6 v which is what a fully charged 4 cell NiMh produces. A 5 cell NiMh does them in! I settled on Futaba 3003 servos for the flying surfaces and 148 for the throttle. The fully charged Life 2S produces about 6.7 v and in my Majestic has not proved a problem with Futaba servos. As for the pipe clearance, the main thing will be to avoid heavy landings of which my 2 mtr F3A birds are also intolerant! The East solution is to rotate the pipe outlet with bigger wheels as my next choice - or both!

The other issue I wanted to check out was the distance from the bottom of the exhaust pipe to the ground. By raising (lowering) the manifold pipe end, I could reduce the pipe's downward cant and, as you can see below, the the end of the curved exhaust pipe is about an inch clear of the ground. The end of the pipe can be rotated to that it points sideways thus increasing the clearance but with a slight amount of thrust which could affect the yaw of the aircraft. A downward facing exhaust may also affect the longitudinal trim. It may be that neither effect is noticeable from the ground - we shall see! And now some pretty shots! The pilot, incidentally, has broken loose at the rear and his head has parted company from his headrest. I suspect that the rough running when running the engine rich is to blame but, for the time being, I've left him alone! I will remove the canopy and re-glue him, once the maiden has been successfully concluded.

This morning's weather was dry but breezy so I decided to check out the performance of the engine with the 14x12 prop fitted. As I said earlier, I have reduced the piston centre to baffle distance down to 22 inches having been told that 21 1/2 inches was the required distance. The first thing I found following start up was that the engine wouldn't accelerate beyond 1/2 throttle so clearly the main needle was set too weak. I opened this up by a turn and then re-set the needle. It settled 1/2 turn richer. The idle, on the other hand was too rich and that needed almost 1/2 turn towards lean. However, the performance was pretty good with max rpm being 8,600 and idle settling on 1,900 for a sustained idle with crisp response to opening the throttle. I was quite pleased with that outcome. I do have 3 other props I can try once I get the maiden out of the way which looks like being next week. According to the APC propeller performance charts, 8,600 rpm on a 14x12N prop is around 10 1/2 lbf. Given the empty weight of the Gangster is 9 1/4 lb and fully fuelled it will be around 10 1/4 lb, the theoretical calculation gives me a 1:1 power to weight ratio. We shall see what happens in practice. Incidentally, 9,100 rpm with the 14x10 prop is quoted at almost 12 lbf. Following cutting down the length of the manifold pipe, I fitted the tuned pipe as close to the manifold as I could. As I said earlier, the quick clips are now usable with the snug fitting silicon pipe and the pipe rests naturally on the rear support as you can see below: Edited By Peter Jenkins on 09/02/2019 19:25:20

Posted by Jonathan M on 07/02/2019 14:52:32: That makes perfect sense Peter - where there's a quickly removable hatch or normally take wings off a bigger model. I suppose I was trying to visualise a solution for a smaller model (like my 60" Middle Phase) where I don't usually have to unscrew the wing bolts to transport or charge. Necessity (howsoever self-inflicted!) being the mum of invention, this now prompts the devising of a wee sliding hatch beside the main switch/port for the for the balance-lead extension Jonathan, you probably don't want this photo now, but as I took it, I thought I'd post it to show the extension of the balance lead from the LiFe pack in the old tank bay and the position of the switch which you can just see the back of in this photo.