Topic: Nodding Flamingo

Hi there,

I have just aquired a MPX Flamingo Contest which was aero towed today for the first time. It has a tendancy to oscilate in pitch whilst on tow. once off the line it behaves nicely. The c of g is as per the instructions.

What are we doing wrong?

and if anyone has had one of these i would like to pick your brains regarding the setup.

A couple of suggestions:
1. add in a bit of down trim for the next aerotow, then take it out when released - sounds like you've got the plane trimmed ok for glide - but on tow its going faster, so will try & pitch up i.e. add a bit of down trim. IIRC that's what I was doing on a full-sized aerotow - but i had my hands full at the time just following the tug plane

2. do the "dive test" to get the CofG sorted (which probably isnt the same place as in the instructions - it'll probably end up further aft) - then have another go!

and as for "what are we doing wrong" - the answer is "nothing, except that plane was never intended for aerotowing" - but don't let that stop you - aerotow is great fun.  

Phil.

Are you towing from a tow hook or tow release?  It may be that the attachment point is too rearward.

Are you towing from a tow hook or tow release?  It may be that the attachment point is too rearward.

+1    good point - aerotow attachment needs to be on the nose, or near

Phil.

we are towing from approx 4" from the nose tip to one side of the fuz.
 
I am hoping to slope it tomorrow. I know its an old design but as a step up from an easyglider it gave me a big smile today.

I have mixed aileron with flap  but have not yet put in coordinated rudder.
 I am hoping someone on here may be able to trawl their memory back to the 1980s and remember what the ideal setup was.

i will try a bit of downtrim, although, as i am trying to stay on station above the tug will i not just undo the trim change as i fly the elevator?

Tow release location sounds ok then.

I had a Kranich about 10+ years ago, which is the electric version of the Flamingo (I think).  I don't remember it having flaps, but ailerons and spoilers.  It also had an all moving tail, so if yours has the same that at least we can rule out tail incidence as an issue.  As an aside I can remember rigging it with the incidence pin resting on (not through) the bell crank one day by accident and that made for an interesting launch at 600 watts.

So if it's not the tail incidence, then nodding is most likely due to c of g issues as described by Phil above.  Flying at the slope should help with diagnosis.

As regards other settings, then I do remember that coupled rudder and aileron helped turns in light lift, but no coupling was required in good lift and the roll rate was quite tidy.

One other thing about all moving tails - the amount of movement required for good pitch authority is more than you would expect compared to a conventional elevator.

Yes, the Kranich is a leccy Flamingo. The Contest version of the Flam gives you the option of flaps, to allow you nail those spot landings with crow.

Thanks for the advice regarding rudder coupling.  i will put it on a switch as i do not want it on tow.

cheers

andy

ps you dont have a spare wing joiner do you as I have a spare fuz and a spare set of wings!!

Hi slope Dragon.
hope you don't mind me joining in. I have just got a new Kranich,was wondering what set up ;(Motor-- ESC) you had in yours.And being
new to the electric side of gliding, I am just feeling my way through the mine field.Any input would be appreciated
cheers.
Jack.













                                         

Hello Jack

I sold the Kranich on quite a while ago, so this is from memory.  I think that I had a Lehner 1920 inrunner brushless, with Reisennaur superchief 7:1 gearbox and 17/11 prop running on 14 SubC cells and Lehner 100amp ESC.  This was probably a bit ott, but the model is relatively heavy for its size and I was aiming for 100 Watt/ib.  Probably 80 Watt/ib would be ok.

This was about 10 years ago, so I would do it differently today.  I would look to use an outrunner brushless, e.g. Axi, or maybe a Mega direct drive inrunner.  Speak to John Emms at Puffin because he has a wide range of motors and is bound to have something to suit.  http://www.puffinmodels.com/index.html

Also I would run with 4 Lipos and keep the amps down to 30 or 40.  A smaller prop such as 15/10 or 13/10 would probably be more appropriate at this voltage, but that will depend on the motor and revs/Volt.

 ???I think some of the information has sunk in?? methinks i will have have to look into some of your information on line. amps and watts i understand ,the rest i will investigate, good idea about getting in touch with puffin models..that i will certainly do
many thanks
jack

I had a Kranich too, a very early one. It was fitted with the Multiplex propulsion system as at that time brushless motors were very exotic/expensive. This was a very large brushed motor running direct drive I think. I ran on 10 cells, 2400's if I remember correctly. One thing you will need to consider is that the nose is relatively short/ back end rather heavy. Getting as much as possible up front will be important for you CG. The model was a bit of a brick but had a surprisingly good performance, and with the flaps,(crow) and airbrakes you could land on a sixpence if an aggresive approach technique was used.