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Bob Grimstead
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Posted Wednesday, January 3, 2007 @ 03:34 AM  

I have had lots of e-mailed advice from other Fournier aerobatic pilots on the specific requirements of this particular little airplane. These are not my advice, and I take no responsibility for your actions, but I’ll share some of it with you…

Get lots of dual spinning practise with a proper instructor in a proper airplane (not a PA-28 or a Cessna) before you try spinning the RF4 solo. It goes straight into a fully-developed spin, and rotates well nose-down and pretty quickly. More than a couple of turns make me sick, and can be very disorienting. It WILL NOT RECOVER unless you take the proper recovery action.

SPINS: The Fournier spins quite energetically. Check your C of G is in the right place (properly) before you even try spinning. Don’t spin a modified airplane.

Climb to 5,000 feet over an unpopulated area (or 6,000, or 7,000 -- you can't be too high for your first single-seater spins).

This is a 'competition' spin:

It takes about 1/2 to 3/4 turn to come out of more than two turns of a spin. Pick a line. Wings level, ball in the middle. Close the throttle. Slow to the stall. As she starts to stall, apply full rudder in the required direction. Pause. Then, only after she starts to roll, apply full back elevator and she’ll break into the spin proper. Count out loud as you go "quarter, half, three quarters (you have to say one this faster) one, one and quarter, in-spin aileron, opposite rudder, forward stick." For a one-and-a-half-turn spin, initiate your recovery at the one turn mark with full opposite rudder and full forward elevator. The turn rate increases, and then she stops.

Straighten everything out, rudder, ailerons - maintaining forward stick to the vertical as you hit your down line. Check your line. If out, immediately align with ailerons – vigorous movement, you’re going slowly. Hold forward for the count of two. Pull to horizontal - check level. It’s done.

GET PROPER DUAL INSTRUCTION

Good Luck.

Yours, Bob

[size=small][Edit by Bob Grimstead on [TIME]1171854359[/TIME]][/size]

Sam M.
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Posted Tuesday, March 31, 2009 @ 10:52 PM  

did a few spins today, worked out well, i tried a 2 turn that started out fine then after the first turn it started to buffet/shake/ I think it turned into a spiral dive after the first turn. has this happned to you?
Bob Grimstead
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Posted Wednesday, April 1, 2009 @ 06:41 PM  

Hi Sam,

I can honestly say I've never had that happen in an RF4. Both mine have their center of gravity in the mid-range. Is yours anywhere different? And is your idle rpm around 800?

Nowadays I often fly five turn spins, and after the first rotation, which can sometimes pitch up and down a little, it generally steadies into a fast, predictable nose-low spin. See http://www.youtube.com/watch?v=hron6ddfctc

I prefer to spin to the left, simply because I find the recovery on to a specific display line a little more predictable. Going to the right it can sometimes be a little slow to recover and goes past the heading I want.

I enter with the throttle completely closed, by letting the nose rise gently (slow deceleration - one knot or mph per second) until less than a knot before the stall. Then I gently (taking maybe half a second) apply full left rudder and hold it there. As the nose yaws and starts to drop away sideways, I pull the stick centrally all the way to the back stop (again taking around half a second) and hold that there. The ailerons will try to pull the stick over towards the direction of the spin, but I resist that.

Within one turn (and often immediately) the spin stabilises into a steady rotation. I don't think I've ever experienced buffet or shking, although I have often experienced that in a Chipmunk (which tends to transition into a spiral dive). Maybe, as you suggest, the stick was not held firmly against the back-stop and your spin transitioned into a spiral dive. I admit I've never looked at my ASI in the spin, but it should read low, I'd guess around 40-50 in a true spin (with the pitot out on one wing it would probably vary by ten knots depending upon direction. In a spiral dive it would be higher and probably increasing.

For my on-line recovery, I fly a non-standard recovery. Be sure to talk about this with other experienced aerobatic people and experiment high and with a parachute before trying it yourself. I take no responsibility that it will work well in another Fournier, although it works fine in both of ours.

Three-quarters of a turn before the required exit heading, I apply full in-spin aileron and full opposite rudder. A moment later I move the stick well forwards (taking between half a second and one second). When I feel the yawing stop (although the airplane's still rotating, thanks to all that aileron) I apply full power and keep pushing down the nose until we're almost vertical. When I'm heading the right way, I centralise the ailerons

I just arrived back in Austrlia today after a month in Englnd trying to sort out buying an RF5 between ten of us -- but that's another story.

I have to finish putting the wing back on the blue one, but should be able to do that within the next week. Then I have a good excuse to go and do some spinning experimentation, to see if I can repolicate your buffet.

I'll let you know what I discover.

Yours, Bob

Sam M.
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Posted Wednesday, April 1, 2009 @ 11:26 PM  

thanks Bob, i was planning on doing spins today,went surfing instead.in the next few days i wll try your technique.
Collin
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Posted Thursday, April 2, 2009 @ 01:00 PM  

Hi,

I just read Sammy Mason's book. Stalls, Spins and Safety. I recommend it for any pilot.

Collin

Bob Grimstead
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Posted Wednesday, April 22, 2009 @ 07:02 AM  

Hi again Sam,

I have at last had a chance to fly a few experimental spins. Several. Up to six turns each way.

You are right, there is slight buffet all the time in all of them, but if you relax the backpressure on the stick it transitions into a spiral dive.
I was surprised at the airspeed in a steady spin.
It seems to settle at a surprisingly high speed -- around 60-70 knots (70-80 mph).

However, if you relax the backpressure and let it become a spiral dive, the airspeed increases rapidly and the g-force increases noticeably. I could not discern any appreciable increase in the buffet, which is only ever slight.

I have also noticed that if you allow the stick to move sideways, it will do so, as it does in the snap roll.

I haven't yet experimented with in-spin and out-spin aileron, so I can only suggest you hold the stick hard back and in the center.

Have fun, and don't get too dizzy!

Yours, Bob

Sam M.
First Sergeant

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Posted Wednesday, April 22, 2009 @ 12:36 PM  

Thanks Bob

I always appreciate you being a testpilot for me!
I will practice some more spins soon.

Sam

Mike-RM
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Posted Saturday, April 25, 2009 @ 09:36 AM  

When I flew RF-4-s at Sportair in the early 1970's I was advised by the instructors that the airspeed indicated in the spin was high and that's what I found, as Bob indicated - 70-80mph sounds about what I found. I was never sure if it was really a spiral dive. I'm quite light and a heavier pilot might get a better spin.

When I had a share in RF-3 G-ATBP, about the same time, the PFA permit cleared it for spinning, but the spin was uncomfortable and oscilliatory with a lot of creaking and groaning so I only did it once. It's not cleared now.

Our RF-5 spins well with someone in the back to get the c of g aft. It recovers in about a quarter of a turn and it's not too difficult to exit on a heading, but it won't spin solo, going into a spiral dive.

Mike

[Edit by Mike-RM on Saturday, April 25, 2009 @ 09:38 AM]

Sam M.
First Sergeant

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Posted Saturday, April 25, 2009 @ 11:44 PM  

I only weigh 135 minus parachute, maybe lifting some weights would help...haha
Donald
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Posted Sunday, April 26, 2009 @ 03:46 AM  

Quote:
Originally posted by Mike-RM
When I had a share in RF-3 G-ATBP, about the same time, the PFA permit cleared it for spinning, but the spin was uncomfortable and oscilliatory with a lot of creaking and groaning so I only did it once. It's not cleared now.

Au contraire. The Certificate of Airworthiness for G-ATBP clears her for spinning although her BGA issued manual says not. Some years ago I took up this contradiction with the CAA and they were insistent that if the CofA said so then it was allowed. I have spun her though not often and I have not let it develop beyond about one turn so I'm no expert in her characteristics.

[Edit by Donald on Sunday, April 26, 2009 @ 03:47 AM]

Bob Grimstead
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Posted Sunday, April 26, 2009 @ 10:31 PM  

Hi Guys,

To verify one of Mike's points, the manoeuvre described above is definitely a spin and not a spiral dive, despite the surprisingly high airspeed.
The proof is that, while the airspeed fluctuates a little, it does not increase at all until either you recover, or, if you relax the stick backpressure, the aeroplane transitions into a spiral dive. This is immediately obvious from the increase in noise, g-forces and airspeed.
To confirm this and to perfect my spins and flick rolls, I flew the blue one with wool tufts on its wings. They stick up and dance on most of the inboard wing during the spin.
And you can see the airflow (angle of attack / alpha) on the inner wing's tip is at almost forty degrees to the leading edge in second half of this clip. http://www.youtube.com/watch?v=hron6ddfctc

Yours, Bob

Bob Grimstead
Captain

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Posted Sunday, April 26, 2009 @ 10:40 PM  

and here is a couple of photos...

Yours, Bob

Bob Grimstead
Captain

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Posted Tuesday, January 12, 2010 @ 11:38 PM  

Hi Guys,

In the multiple interests of flight safety, fun and investigation, yesterday I made a five-turn spin each way with my in-cockpit camera, to see a few instrument readings.

From these clips, you should be able to count turns, take timings etc, so you don't have to worry about doing that stuff yourself when you spin, and concentrate on just flying the aeroplane and looking outside.

Configuration: aerobatic weight, just me and about 12-13 litres of fuel.
I also had two smoke pods, filled with smokes on each wing-tip.
In other words, the most aft C of G and the heaviest rotational inertia -- the worst case!
Same as my six-turn display spin all last season.

However, for reasons I cannot start to explain, although as expected the left spin took 200 degrees to recover and the right spin took around 240 degrees to recover (both normal), in both cases they had already started to pitch down and the speed had started to increase by around turn 3 or 4 despite my holding full back stick, full in-spin rudder and the ailerons centralised as best I could.
In other words, they were well on the way to transitioning into spiral dives.

I have no idea why, and I don't think it ever happened to me before (not in the RF4, but it has in the Chipmunk).
Maybe the tickover was slower due to the extra-rich mixture and unusual height of 6,000 and then 5,000 feet.
It certainly looks like a very slow tickover on the gauges.

Anyhow, I hope it's of use, and you don't get too dizzy emulating me.

They're up on YouTube at:

http://www.youtube.com/watch?v=GKXdQt-hvH8

and

http://www.youtube.com/watch?v=69IEcYZXXnY

Enjoy.

Yours, Bob

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