Genghis the Engineer

I was out blowing the cobwebs away this evening in my Goldwing, which is a strange but enjoyable aeroplane I keep myself amused with on a summers evening.



I briefed myself for a couple of stalls, which I hadn't done in the type for a while. The stall is conventionally control limited (full back stick, slight pitch nod, smidgeon of right wing drop) as usual. Recovering with a conventional full power, central stick recovery was conventional (about 50ft delta-H), but then for some reason I decided to fly one with a stick only recovery - basically recovering to the glide.

I found myself with the stick on the front stop, the ASI pegged about Vs+10, a flat attitude, and no control over the aeroplane to speak off. Some mild yawing oscillations too, which is disconcerting at low speed. I recovered with full power, which bunted it somewhat and I just kept within Vne, losing a total of about 700ft.

My conclusion is that the aircraft (which has a very high thrustline, and thus a pretty large pitch-down with power selection) simply lacked the elevator power to recover without my using the power to pitch down. But, I can't honestly say I've ever met the characteristics before - in a modern non-homebuilt type no-doubt this would be unacceptable anyway, and possibly even then.

Any thoughts anybody. I'd particularly be interested if anybody has experience of canard spinning - could those yawing oscillations get me into a spin? How does an aircraft like this spin (and how would you recover it), I honestly have no idea?

G

[ 16 July 2001: Message edited by: Genghis the Engineer ]

Max Brakin

Interesting little area you got yourself into there Genghis. A few questions though..
1. What speed range do you have Vs - Vne?
2. What were you doing on the rudder pedals at the time (DR excitation possibly)?
3. How does your stead handle when gliding, or have you not tried?
4. Is it possible to change the gearing to the canard?

Sounds like flight test in it's truest form, 'oo errr how do I get out of this' but joking aside have you since tried stick recoveries with varying amounts of power applied? And lastly would it have been possible to rudder the aircraft into a roll which would've dropped the nose to gain more airspeed.

Not much help at the minute but interested to see answers.

Genghis the Engineer

1. Stalls around 25-30, Vne is 61 (which I suspect is grossly conservative, but don't have any data to prove otherwise). [This is all IAS, but I think CAS is pretty close, I really aught to go up with a GPS and calibrate it.]
2. Nothing (and incidentally the fins are split so left rudder gives outgoing left fin and nothing on the right)
3. Comfortable in smooth air, with moderate pitch control (much less elevator power than at higher speed) but the ailerons (well mixed spoilers and ailerons) are very non-linear below 45, so I use rudder for roll control down there. Best glide is about 35 kn / 200 fpm.
4. No, and given that at high speeds (55-58 kn MCP cruise) it is overpowered (moderate pitch displacements, very low forces) with a noticeable tendency to enter a PIO I'm not sure it would be a good idea.

I haven't flown it since (weather has just clagged in over here and it's firmly a fair weather machine, due to the combination of very low wing loading and a canard), but your suggestion of trying different power settings in the recovery is a good one which I'll explore when the Wx improves.

I'm not sure whether a rudder-induced roll would drop the nose, and in any case have a moral aversion to applying large amounts of rudder around the stall unless I'm wearing a parachute.

Thanks for your input, any further thoughts gratefully received.

G

Max Brakin

Genghis: Sounds like you came out bang on glide speed did the canard still give pitch up if you took if of the front stop. If it did then I'm in your camp with the lack of control power( though the moment arm for the canard to work with doesn't look very big)
Have you managed to get any other similar stories from people who fly the same type.
Bet you don't try it again too quickly..Fly safe

henry crun

I am in no way qualified to answer the questions you ask but I have one for you. I thought that one of the advantages of a canard is that the relative incidence between the mainplane and the foreplane is arranged so that the foreplane stalls first and thus automatically lowers the nose into recovery. This is obviously not the case with your aircraft if the elevator power is insufficient and needs the assistance of power from the high thrust line. Do you know why it was designed like this ?.

Genghis the Engineer

Much as I enjoy flying the Goldwing, the word "designed" should probably be used loosely in this context. The designer was a 19 year old American and I could point out many aspects of it that are somewhat less than ideal.

However if I'm generous for a moment and assume that this was thought through, it is a small and very flat aircraft on the ground, so to fit a reasonable propeller diameter you need a high thrustline - the only other option would be a much higher undercarriage, which then gives rise to ground handling issues. Assuming that is the reason for the high thrustline, the rest is presumably designed to compensate for that. The short-coupled canard (which is very noticeable in handling) I think is due to the design requirement that it must de-rig and fit easily into a road trailer.

G

[ 19 July 2001: Message edited by: Genghis the Engineer ]

tgrendl

I have no experience with this (being a helo-type) but remember vaguely that one of the kit type aircraft (US 1985-95) with canard had the same type of problem.

A fair amount of these were sold, sorry I don't remember the name either.

Try the archives at plane and pilot, sport aviation or private pilot.

As I remember it quite a bit of testing and troubleshooting went on to discover what caused the issue.

Hope this helps a bit

HeloTeacher

The Velocity kit had some deep-stall problems where the aft wing stalled due to excessive aft CofG location and recovery wasn't possible. The ensuing glide was slow and survivable except when the a/c rolled inverted.

They fixed it with wing cuffs and CofG limitation.

I'm not an expert, just an avid reader and enthusiast of the experimental genre.