Author |
Messages |
Bob Grimstead
Captain
Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2029
|
Posted Wednesday, January 3, 2007 @ 03:19 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…
Climb to 5,000 feet over an unpopulated area. Trim to your maximum level speed (around 90 kt with a 1,200cc engine, maybe 100 kt with the 1,400). Flying the Fournier aerobatically is an energy management exercise. It is only a glider with noise in front.
LOOPS: For a straight loop, first start with everything level - speed 100-110 knots (you can loop from as little as 80kt but that comes later). Dive to get your speed (don’t hold the dive for too long - just do it). Pick a straight ground line. Pull smartly & firmly into first 1/4 of the loop (around 4g). Be sure you pull straight back towards your sternum, not towards your right elbow (which we all do for the first year!) Check your wings bisect the horizon on both sides; if not, ease them straight with rudder (do not relax your pressure on the stick). Keep pulling to the inverted, but ease off the pressure as you go through about 140 degrees nose-up. Check your line and wings; correct any dropped wing with aileron. Check wings level both sides (look both ways). Float very gently over the top with almost zero g, but don’t let the engine stop. You'll need quite a lot of left rudder here. Look up to check your ground line at the same time though the top of the canopy - correct any deviations with generous rudder and appropriate aileron (the airspeed will be around 30, or maybe less). Pull very gently (like milking a mouse, you don’t want to stall) into the third quarter of the loop. Check your wings are bisecting the horizon evenly on the down vertical. Check your line on your ground marker. Pull firmly on the last quarter of the loop.
If done correctly you should finish at the same height at which you commenced, and in still air you should hit your own wake.
If you want a circular loop, you need to think about your pitch rate. If you started at 120 knots, but are only going at 30 knots over the top (quite normal for a big loop) your pitch rate at the beginning and end will need to be four times that over the top. Put another way, for a circular loop, as soon as your speed starts reducing, your pitch rate (pull) should start reducing, and it should only be one quarter over the top compared to the start and finish (even less for a downwind competition loop). It is hard in the RF4 to maintain such a low pitch rate without getting a little negative G, whereupon the engine stops, your elevator is robbed of airflow and the nose drops, giving you a very wonky loop.
Yes, I know the above loop does not appear to be circular, but I think (hope) the kink at top right was due to me flying through my earlier wake, rather than prodding the stick. I leave it to you to play with loop shapes.
Good luck, have fun, AND GET PROPER DUAL INSTRUCTION.
Happy Fournicating, Bob
[Edit by Bob Grimstead on Friday, January 5, 2007 @ 02:35 AM]
[Edit by Bob Grimstead on Sunday, January 14, 2007 @ 11:47 PM]
|
Sam M.
First Sergeant
Gender: Male
Location: Santa Paula, CA
Registered: Jul 2008
Status: Offline
Posts: 228
|
Posted Friday, January 9, 2009 @ 10:21 PM
Hey Bob,
I was experimenting with loops the other day, and found i could start at 125mph exactly 3000ft pull 2.4 gs (sometimes a little less) and come out on heading and alltitude. It Wasn't round but it was fun!
|
Bob Grimstead
Captain
Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2029
|
Posted Saturday, January 10, 2009 @ 02:11 AM
Hey Sam,
That's the great thing about Fournier aerobatics, they're fun and easy.
To make the loop more circular, try easing off the back-pressure on the stick as the horizon comes into view ahead. Don't overdo it or the engine will stop producing power (but don't worry, the prop won't stop unless you actually push). In a really round loop the airspeed will drop to almost nothing at its lowest point as you float over the back of the loop. 40-50 mph is very common.
Have fun in your Californian winter.
It's too hot in Australia for me to fly today.
Yours, Bob
|
Sam M.
First Sergeant
Gender: Male
Location: Santa Paula, CA
Registered: Jul 2008
Status: Offline
Posts: 228
|
Posted Saturday, January 10, 2009 @ 02:18 AM
It Was too windy here 30 to 40 mph of Santa anna Winds!
The saying in Santa Paula is you get 2 inches of rain, the 4 inches of Santa Annas!
|
Bob Grimstead
Captain
Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2029
|
Posted Saturday, January 10, 2009 @ 02:27 AM
Hi again Sam,
I bet all the European guys are still jealous of us.
It has been freezing over there!
I found this recent pic of a loop.
I think they're gradually getting better in shape.
Smoke sure helps to visualise the shape, but using a fixed camcorder with a wide-angle lens and then tracing it on a big TV screen works well too.
Yours, Bob
|
Bob Grimstead
Captain
Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2029
|
Posted Monday, March 7, 2011 @ 04:29 AM
Hi Folks,
In the interests of trying to assist everybody with their aerobatics, I've taken a few in-cockpit photos. To keep the image size within the confines of these pages I've had to reduce the resolution a little, but I will try to explain to help out.
This is pulling up into a circular loop. The speed is 100 Knots (115 mph), so I probably started five knots/mph faster.
I am pulling 4G. To get a round loop, you need to get to 4G quickly, but without jerking, but then you immediately start letting the G reduce as your airspeed reduces.
For a circular loop, the higher your airspeed, the higher your pitch-rate (and G) needs to be, so it starts off at 4G or so, reducing to zero at the top, and increasing again down the back side of the loop as your airspeed increases again.
The slip ball should of course be centered all the way around your loop.
The VSI (variometer) is of course lagging hours behind real-time, so it's still indicating the preceeding dive.
Now I'm vertical, going upwards.
You will see that I am looking out to my right wing-tip.
Never just look straight ahead in a loop. There is nothing to see out there.
You need to flick your head from side to side to check that your wings are equidistant above the horizon to ensure you are looping straight ahead.
The speed's dropping back through 85, the rpm are falling and the G is reducing through 2G, but the slip ball should still be centered, so left rudder is gradually being applied as the airspeed falls.
Now I'm inverted at the top.
The airspeed is back to 30, the G is very close to zero and I am pitching oh-so-slowly as she very gently floats ballistically, weightless over the top.
If your airspeed is much higher than 40 here, you will need to close your throttle in the third quarter, going downward, to prevent going supersonic and blowing off your wings.
Depending on your propeller, you should have between half and full left rudder here to stay in balance.
But my wings are not level. Big error there!
Now we're going vertically downwards.
Again, my head is just moving to look forwards after having been checking my left and right wing-tips are equidistant above the horizon.
The airspeed is rapidly increasing through 75, the G is also increasing at 4.5 to keep the airspeed under control and to round out the bottom of the loop, but the slip ball should still be centered as the left rudder pressure reduces.
That's it.
If you have a 1400cc engine, you should end up at pretty much the same height and speed at the end as you had at the beginning, provided you keep full power all the way around, pulling more G (at least 4G) in the third quarter to keep your speed and height under control and to finish off the bottom of your loop circularly.
Have fun, and always do this with an instructor before you try to do it solo!
Yours, Bob
[Edit by Bob Grimstead on Monday, March 7, 2011 @ 04:46 AM]
[Edit by Bob Grimstead on Monday, March 7, 2011 @ 04:49 AM]
-------------------- Flying and displaying Fournier RF4Ds VH-HDO and G-AWGN, building replica RF6B G-RFGB and custodian of RF6B prototype F-BPXV
|
jb92563
Second Lieutenant
Gender: Male
Location: Lake Elsinore, CA, USA
Registered: Mar 2007
Status: Offline
Posts: 583
|
Posted Monday, March 28, 2011 @ 03:30 PM
Great description of an RF4D loop.
I never realized that so much rudder would be required.
This year I should finally get to do some aerobatic training, I have been waiting quite a while and have just been too busy,
and a recover project for the fuselage thrown in so I don't have to apologize for the unsightly paint cracking.
I'll be reading all the notes on this forum as I progress so I do appreciate all the time taken to document with notes, pictures and video.
I too have a GoPro now and will have to document my progress as I go.
-------------------- Ray
RF4D #4057 N-1771 Rectimo 1400cc
http://picasaweb.google.com/jb92563/FournierRF4D
http://www.touringmotorgliders.org
|
Bob Grimstead
Captain
Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2029
|
Posted Wednesday, March 30, 2011 @ 08:49 AM
That's great Ray,
I hope you enjoy it.
Remember, make only short flights at first, so that you don't feel too queasy.
If I haven't flown aerobatics for a few weeks, my motion tolerance drops right off.
Let us know how you go.
Yours, Bob
-------------------- Flying and displaying Fournier RF4Ds VH-HDO and G-AWGN, building replica RF6B G-RFGB and custodian of RF6B prototype F-BPXV
|
Sam M.
First Sergeant
Gender: Male
Location: Santa Paula, CA
Registered: Jul 2008
Status: Offline
Posts: 228
|
Posted Saturday, April 2, 2011 @ 08:38 PM
Ray, Come down to SZP, fly out of CP. They have a 2004 super decathlon, still rolls about double the RF, but you can do half deflection rolls. And you dont have to sit burning gas talking clearance at John Wayne!
|
|