Posted by Ray Phillips on Tuesday, November 30, 2010 @ 03:43 PM:
Our club just bought an RF5B. Now we have some questions.
First is the tail wheel. Our has a weight attached to the top of the TW shaft. This shaft broke and the TW fell out and did some minor damage to the rudder. The mounting of this weight seems poor to us. How have others mounted this weight?
Weight and Balance question. Our paper work showes 50 lbs required in the rear seat to fly solo to keep teh CG from going out of forward limits. . Is this typical for the FR5B? We plan to reweigh the ship and do the WB calulations to see what we have.
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Posted by jb92563 on Tuesday, November 30, 2010 @ 04:45 PM:
Welcome to the Fournierteer club Ray.
I have an RF4D so I can't help you with that W&B info but some others guys will chime in soon no doubt.
In the mean time can you tell us a bit about your club and the RF5B?
What is the N- number?
Who was the former owner?
Got any pictures?
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Posted by eugenio on Tuesday, November 30, 2010 @ 04:51 PM:
The weight on the tailwheel is to balance the weight of the variable pitch propeller. Also on RF5 (the short wing RF5) when swithching from Limbach 1700 with wooden fixed pitch prop and exhaust stack like the RF4 to Limbach 2000, silenced exhaust and variable pitch prop a balance weight had to be added in the rear part of the fuselage.
You must first check the WB of the aircraft, then you can install the ballast fixing it with the fin fixing bolts (4 M8 bolts from the fin into the fuselage) if you have enough room, or you can mold the lead in a way that you can fix it on top of the tailwheel box. (I mean the top of the plywood box where the whole tailwheel is bolted, where you see a big washer with four wing nuts)
You should screw the lead to the plywood not to the tailwheel.
It is uncommon to have to add weight on the rear seat, also if you can have a forward CG.
Eugenio
Posted by Ray Phillips on Tuesday, November 30, 2010 @ 05:41 PM:
Yes, we are soaring club in NY state. We fly from Tri Cites airport (CZG) about 50 miles east of Elmira. We have owned various gliders and a tow plane over the years. The RF5B is new to us. We bought it from a gentleman in Pittsburg, PA. We have about 7 members all glider and/or power pilots. We are looking forward to getting advice and help from people in this forum. N55GS Thank You..
[Edit by Ray Phillips on Tuesday, November 30, 2010 @ 05:44 PM]
[Edit by Ray Phillips on Tuesday, November 30, 2010 @ 05:45 PM]
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Posted by Jorgen on Tuesday, November 30, 2010 @ 06:01 PM:
Hi Ray Phillips (there is another Ray (jb92563) here),
wellcome and congratulations to an excellent choice. Our RF 5 b is unfortunately a repairproject at the moment, but I can vouch for what Eugenio says. "SE-UDI" broke off the tailwheel and split the rear fuse in a bad ground loop and did not have any counter weight in the tail (at least none that I have found so far) and with the Limbach 2000 + three-pitch Hoffmann prop the CG was severely in front when flown solo- I had to have the stick in my gut all the time when gliding, even with half fuel. I actually hope to "gain" some weight in the rear by the upcoming rear fuselage repair to counter that. In the weight and balance sheat I have the 50 lb rear seat weight is mentioned if I remember correctly and I think James Bavendam uses that too when he solos. I think it makes more sense to add a minor weight in the tail. One of the great advantages with the RF 5b is the quite agreeable minimum sink, which comes in much more handy for soaring than glide performance.
May the 4's be with you/ Jörgen
Posted by JamesB on Wednesday, December 1, 2010 @ 11:46 AM:
Sorry to hear about the ground loop & damage.
I have a 40lb exercise vest that I strap into the rear seat to give me a more neutral stick when I soar. My RF5B flies well without it. I just enjoyed the neutral stick when I bring a passenger for soaring, so I started bringing the vest. Your CG calculations should be your guide about any weight changes. I don't know if any ballast is in the tail of my RF5B--never looked for it.
Thanks for sharing the information. I'll keep in mind that the tail is lighter and possibly more susceptible to a ground loop when I'm flying solo. Never really thought about it that way.
Posted by Jorgen on Wednesday, December 1, 2010 @ 06:05 PM:
Hi James,
check out this thread for pictures and info on the sorry state of "SE-UDI" at the moment:
http://sbeaver.com/cgi-bin/fournier/cutecast.pl?session=UwEcwCUsO7AJ6cM0gtPwjcPV2k&forum=11&thread=622
The light tail is perhaps not a risk for ground loops in itself, but the tailwheel does not take a whole lot of lateral punishment before it breaks off. This is something worth considering with a 17 meter wing span.
Ray Phillips,
from your description I'm not sure I understand what type of damage you had to your tailwheel- is the wooden attachment still intact? It is a bit awkward to post pictures on this forum (there is a thread on how to do it under the "miscellaneous" section) but that would help us to assess your problems.
May the 4's be with you/ Jörgen
Posted by Ray Phillips on Wednesday, December 1, 2010 @ 07:41 PM:
No real damage other than to the bottom of the rudder due to landing with the tail wheel hanging from the springs. The tail wheel is attached with a single bolt the holds the inner bearing to the race. In our case, this bolt was a long stud going through the tail weight. This 7 pound weight was on top of the tail wheel and rotates with the tail wheel steering. We also had some problems with tail wheel shimmy. Being that the RF5B is new to us, we were not aware of the weight attachment or if shimmy was any kind of a problem. The dynamics of the weight moving on top of the shimmimg tail wheel caused the stud to become loose. The stud then broke and the tail wheel assembly departed the aircraft.
I understand the weight is required due to the increased weight forward of the firewall on later ships. We are also now aware of a service note to apply loctite to this stud. Overall, we think this weight attachment to the tail wheel is not the best design. I am trying get get ideas from other owners on how the weight is attached in their aircraft. One of our ideas is to attach the weight to the same block that mounts the tail wheel and not to the tail wheel shaft.
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Posted by jb92563 on Thursday, December 2, 2010 @ 11:12 AM:
RayP,
Since weight is not an issue, why don't you add a wooden box that glues and bolts into the fuselage sides and is accessable from the top, under the stabilizer, adding additional strength to that area, and fill the box with lead shot so that in case of an accident you don't have a huge projectile flying about.
If you are going to add weight in the tail it might as well be functional and the weight added adjustable (You can vacuum lead shot out from the top access opening), in case you have some equipment changes over time.
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Posted by eugenio on Thursday, December 2, 2010 @ 02:21 PM:
We have here another RF5 with the shimmee problem and we solved it installing a dampener like those used on motorbike. It is not a problem of weight, it is only a problem on some RF5, but I never could find a reason why some do so and some other don't.
Eugenio
Posted by Jorgen on Thursday, December 2, 2010 @ 05:46 PM:
Hi,
I haven´t thought through how to fit a tailweight yet, but I agree it seems to be a bad idea to attach it to the tailwheel itself.
Regarding tailwheel shimmy it might have something to do with the rubber bumper as this might affect the Castor angle. This Guy has some good general info on this web page:
http://www.pierceaero.net/tws.php
and this picture is clarifying:
http://www.pierceaero.net/techdata/tws.jpg
Although the Fournier tailwheel setup is different I think probably the general principles apply.
May the 4's be with you/ Jörgen
[Edit by Jorgen on Wednesday, April 6, 2011 @ 02:16 PM]
Posted by Ray Phillips on Thursday, December 2, 2010 @ 06:53 PM:
Hey guys, thanks for the information and ideas.
We thought this long stud on top of the tail wheel to mount the weight was a standard RF5B installation. No one has said they have the same installation and what experience they have had.
We are in the process of getting the rudder back on.
From what I have read here, the RF5B is nose heavy. How much depend on what ballast weight you are carring and where. The biggest problem with being nose heavy is during soaring flight and needing more back pressure on the stick. This is not a real safety issue, but a just a handling problem.
One thing that may have caused our shimmy is the fact the tail wheel was loose and we did not see it.
Keep the ideas coming and I will tell what we found when we get back in the air.
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Posted by Ray Phillips on Sunday, December 5, 2010 @ 10:12 AM:
We have our RF5B back together and just waiting for the snow to stop so we can fly. The tail wheel has been installed without the tail weight. We plan to fly it this way with a 200 lb person in the rear seat.
We are still investigating on how to mount a weight in the tail.
First there is a brass tail wheel hub that we could buy. This will add back about 3 lbs of the 7 lbs we removed. Does anyone have experience with this heavy hub? Does it change the tail wheel shimmy problems?
While investigating the tail wheel mounting block, we found the area under the bock appears to be hollow. There are 2 drain holes. One forward and one aft of the tail wheel. Inserting a probe into these holes, it does not go up into the inside of the fuse.
We were thinking about drilled a hole to mount the tail weight, but this hollow area is a surprize. Any thoughts for other RF5B owners?
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Posted by Jorgen on Sunday, December 5, 2010 @ 07:11 PM:
Hi Ray,
mailed a picture to you and will post here too. Draining holes in Fourniers is in an Airworthiness directive (sorry, don´t have the number right now) regarding rot in the tail, one of the few weaknesses discovered on Fourniers over time. You should always check that your ship complies with this, check also that the draining holes are indeed open and not plugged with dirt. It makes sense to have a draining hole also in front of the tailwheel (SE-UDI haven't, but I can assure you she didn't split because of rot), more on that as we delve deeper into Fournier RF 5 b tail anatomy. A probe can't reach through since there is a "second floor" in the tailbox where the tailwheel block is fixed.
MAy the 4's be with you/ Jörgen
