Posted: Tue Aug 03, 2010 8:00 am Post subject: R44 cyclic when going solo
Hi. I've just started going solo on the R44. When flying with my instructor, the cyclic is in a nice position just behind my knee. When solo, I knew the lack of his weight would mean more forward cyclic - but it's miles forward! Way beyond my knee which leaves they cyclic floating in mid-air and me having great trouble staying in a decent hover.
Any tips here? I'm about 160 lbs which is just above the minimum weight for solo in an R44. Would adding in ballast help a little / or perhaps a lot? Any feel for how much minimum extra would be needed to make a difference? My instructor is probably about 180 lbs. Or is it a bad idea to get used to flying with ballast and should I get used to that forward position?
Also, the fuel tanks have generally been quite full. Will emptier tanks make this problem even worse? Thanks for any thoughts.
Have you mentioned your questions to your instructor?
What CoG discussions have you had with your instructor?
Please go and 'slap' your instructor if they haven't worked through changing CoG with you! From your questions I fear the Instructor needs one
Have you looked at the CoG for the incident you describe? Has it's position changed now that the instructor has gone? And if there has been a CoG change is it small or large?
For the seconds that it takes have you looked at the CoG if theoretically you have varying loads? (If not I suggest you spend some time getting to know your aircraft in addition to merely learning to fly it)
Some things to think about, then perhaps you'll be able to answer some of your own questions
Why is a minimum pilot weight specified as an aircraft limitation?
Why are you finding more forward cyclic is required?
The aircraft effectively hangs from the mast when airborne. In relation to the mast: Where is the fuel stored? And where do the passengers go?
Do you the pilot have any control over aircraft CoG?
Your instructor should have shown you how the aircraft behaves when its full of fuel with minimal passengers, and also when its full of passengers and light on fuel. There will be a difference I'd have started covering this pre solo when I was FI'ing. If you haven't been shown it, insist that you are shown it within your course! (and consider changing FI's 'cos if this has been missed/ignored there are better out there)
What issues about using ballast concern you?
(Not having a go at you. You don't know, what you don't know. But I am trying to get you thinking ) _________________ W.Y.S.I.W.Y.G.
Joined: Feb 14, 2008 Posts: 888 Location: Stavanger, Norway
Posted: Tue Aug 03, 2010 1:25 pm Post subject:
If you have flown the R22 before and perhaps most of your time is on it then you will be use to a weight change on a shorter CofG arm when your instructor gets out. The front seats on the R44 are at a longer CofG arm and therefore a more noticable change in the CofG position when he gets out.
But also you should check the CofG graphs with your FI for solo flight across the whole fuel range (zero to full). Seeing it on paper will give you a clearer understanding of what is happening when people get in and out, and as you burn fuel.
Nothing wrong with throwing in some ballast, we used to use lead plates in a cloth bag, could add or remove as required.
The R44 with one up is quite a different beast to two or four up. I remember the first time I took it out, solo, cyclic forwards, as expected, but the whole thing just felt so light! Masses and masses of power available!
Personally, as long as you're in CoG, I wouldn't bother with extra ballast (my belly suffices nicely most of the time! ). If you're ever in the situation where you've taken three folks somewhere, with as much fuel as you can (i.e. no chance of ballast), dropped them off, then you're on your own, with a good chunk of that early fuel gone... what then? Fly the helicopter according to how it's reacting to your inputs - don't think that because the cyclic is on your knee this time, it will be in the same place next time. Practice will get you used to it!
(That said, nothing wrong with ballast, if deemed necessary, or to keep within CoG)
If it's of any help, I acquired some Weight and Balance calculation spreadsheets for R44 and R22 some time ago. Download here: R22 and R44.
They have an arbitrary set of numbers in for the machines that they were created for - you will need to cross check the arms and weights for the specific heli you are calculating for. However, it gives a good illustration of how the different loading affects it. _________________ J.
With a good chunk of the early fuel gone, the concern is somewhat lessened surely?
Not sure I understand what is the 'concern' there? I was trying to highlight a realistic proposition, whereby you would have a significant and large change in AUW, with little opportunity to correct it.
With regard to a water container, I'm not sure I'd be happy with that. Perhaps several smaller containers, distributed appropriately. But a large container or two, without any kind of baffles inside, I imagine could unsettle a helicopter, couldn't it? Then again, are Robbo fuel tanks baffled? Or perhaps it's just me... _________________ J.
The concern is the original posters.
An aircraft operated within MAUW but with a now significant change in CoG position from that previously experienced/ or expected.
Unless I'm mistaken the original post is questioning the degree of CoG change when a 180lb person leaves the front left seat. The poster now experiencing a heavy fuel mass without the balancing mass of the instructor. The questions ask, additionally, if the effect is normal and if/how it could be lessened.
Would the effect have been as marked if less fuel had been loaded prior to the instructor getting out and our poster flying solo?
In your example if the aircraft is full of passengers, and then fuelled until all up mass is reached, the CoG will be at a certain point. If a significant proportion of fuel is burnt enroute and then the passengers exit there will be a significant reduction in aircraft mass, but would that guarantee a significant change in CoG? The 'hover angle' is primarily a function of CoG not AUW. That being the case the original poster would only be in the same situation if having deposited the passengers the aircraft was refuelled to full. It's why I asked if as a pilot we have any control over aircraft CoG
The considerations would have to include is full fuel necessary for the return leg? Hence my earlier suggestion that an understanding of your aircrafts CoG characteristics is very useful.
The fuel tanks arent fitted with baffles. If for the sake of example a 5 gallon container was filled and then placed beneath the front passenger seat or within the footwell (pedals removed) could the load shift significantly?
As HH suggests looking specifically at the CoG of the aircraft flown, with differing passenger and fuel loads will help the pilot plan fully. A line on a map, weather and notams are but the start. Passenger load, fuel load, sectors, refuelling opportunities, CoG, performance (plus others) all need considering too. Yes, thats possibly more relevant to commercial flights, but the same principles apply - a CPL is basically the same flight test as a PPL merely flown to a greater accuracy. Every trip I fly requires mass and balance calculations. I've manipulated passenger loads, fuel loads and used ballast in order to remain within limits at times.
Low hours doesnt preclude an understanding of the aircraft basics. Practice at extremes of CoG would aid the actual flying/hovering. Discussions like these are the sort of things an FI should be having with a student - flying is the easy bit, captaincy, airmanship (call it what you fancy) is the 'extra bit', and from the original questions (which I'm glad McRotor is asking) I don't get the impression that loading and CoG implications are understood. Happy to be corrected though. _________________ W.Y.S.I.W.Y.G.
You can mod the fuel figure, aircraft basic weight and arm to get the figures for your aircraft but using the sample you are quite close to the rear limit.
It is important to gain experience of how the helicopter will fly both liight and heavy, we lose too many R44s to mishandling because pilots do not anticpate the change in CofG and handling when light and heavey perhaps becasue they are improperly taught.
Use of Ballast will probably help to make the first few trips easier while you gain confidence in your self and your experience grows.
Water is always my favourite if the bottle is full to the brim there is movement but not enough to make any noticable change, it does not slosh from one end to the other (it may do internally but it makes no difference to the mean position of the mass in the aircraft). If you hit something hard with it the bottle breaks and you get wet, no nasty impact with weights (unless the bottle is too hard, dont use glass). _________________ Gary
Thanks for all the feedback. I spent most of the afternoon getting to grips with CoG calculations and downloaded the spreadsheet. This was massively helpful.
By removing the 180lb instructor, I could see instantly that the CoG shifted by a good 4.4 inches rearwards. Hence the (seemingly) huge shift forward in cyclic. Interestingly, with a 160lb me, the CoG (longditude) with full fuel comes in around 102. The limit is 102.5, so it's pretty close.
Even with empty fuel (presumably not ideal!) it moves forward by about 1 inch.
Adding about 40lbs of ballast pulls the CoG forward by about 1.5 inches. And a further 20lbs under my seat would retrieve another 0.5
Instructor had gone over the CoG principles with me, but to be honest I hadn't really 'got' it. Working it out from first principles and then a spreadsheet was how it clicked.
Going forward - plan to chat with instructor. I suspect that when I fly solo (after passing test), I would always stick in some ballast (why not make things as easy as possible), but can see the benefit of being able to handle the machine without any - just in case that situation were to happen.
Either that, or it's down to McDonalds for me to fatten up! Big Macs all round.
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