RE: COMP ARF 110
 

Paul,
thanks for the tip: 45 lbs landing on those gear doors can't be good!

===================
CG

The manual says 1/2" in front of the main spar.
I don't have the LE oil/radiator coolers in yet so I just measured there and got 7" to the spar so my mark on the bottom center of the wing is 6.5".
I used some of that 2" thick pink foam and a ply base to make a CG stand.
I made a paper template of the center wing area and transferred it to the foam.
I used my scroll saw as that produced the cleanest cut with no pink waste 'flying all over'!
To handle the large amount of weight, I'm just leaving the entire 2" of foam contact the wing.
One h@ll of a lot of lead buckshot is needed to balance the plane: probably about 10 lbs.
All weight will be added just inside the fire wall at the bottom of the fuse (with that radial, there really is no option for weight in front of the fire wall and I like to keep the cowl as light as possible).
Naturally, CG is checked with the gear up.
When the gear goes down, the CG definitely moves forward.

Please post what kind of weight was needed on your comparf F4U so I'll know if I'm in the 'ball park'.

pic 1:
paper template

pic 2:
scroll saw to cut foam.

pic 3:
CG stand

pic 4:
balance

pic 5:
CG mark

pic 6:
lots of weight!

pic 7:
gear up
The tail is just touching the foam as the plane will 'rock' at the CG.

pic 8:
gear down.
Should I have an issue with too tail heavy on the maiden, I can lower the gear to move the CG forward.

RE: COMP ARF 110
 

CM-6 plugs;

Tower now sells these so if you only need one at 8 bucks (and you're getting other stuff), no problem:
but if you need 5, go here at $1.97 plus 7 bucks shipping.

http://www.boats.net/parts/detail/ho...052-56471.html

RE: COMP ARF 110
 

MODS (fine tuning)

One aileron edge was snagging on the TE of the wing so I used a BVM thin metal 'sander' to remove some of the TE at a 45 degree angle (without having to sand any of the wings surface).
I'm a little concern about some slop in the ailerons as they move about an 1/8". They were moving about a 1/4" but I put the original eyelets back into the servo rubber mounts. I had to cut one side of the eyelets so the machine screw would fit into the eyelet (the screw attaches to an L shaped, aluminum servo mount). The split eyelet filled up some slop between the rubber grommet and screw so the servo no longer moves when force is applied to it. I replaced the hs-645 130 oz with a hs-5645 digital 160 oz but there's still a little movement in the servo arm. I have some 300 oz servos on the elevator and they don't move: I may have to do the same on the ailerons. I'll find out if I get any flutter.
The outside flaps were moving too far compared to the inner flaps so I move the socket screw in two holes on the servo arm to reduce the throw.

pic 1:
Razor saw to cut a slit in the eyelets.

pic 2:
HS-5645 with metal arm installed in aileron.

pic 3:
The servo no longer flexes in the mounts, under load.
One side of the wood mount needed a notch for the servo wire so I couldn't put a servo screw in one aluminum hole so I put a couple along the edge to insure no movement.

pic 4:
A thin metal sander to clean up the inside edges of the TE of the wing so one aileron doesn't snag on it.

pic 5:
Outside flap servo socket moved in two holes to reduce flap movement.

RE: COMP ARF 110
 

Sam

I would think a Corsair is a Corsair, big or small, so based on my T/F G/S @ 29+ lbs your bird is way to tail heavy with the gear up, to get a good flying bird I would suggest a position with the gear up to be about what you have now with the gear down.

I would also suggest using a venasa rig to do your final balaning.

hope this helps

Cheers Bob T
Corsair Brotherhood #5

RE: COMP ARF 110
 

Sam:

I emailed comp-arf support and the salesman and never got an answer. Maybe you can try again. I wanted to know if the recommended cg was with the gear up or down. Standard practice is with the gear up but comp-arf does not do everything the standard way.

So I reverted to using my brain. From my experience, most planes balance on the wing spar. I found out that mine balanced a little tail heavy on the spar with the GEAR UP. Then I put the balancer 1/2' in front of the spar and with the GEAR DOWN, it still balanced a little tail heavy (2lbs required on the firewall) and off course was very tail heavy with the gear up. I knew it would fly ok if it balanced close to the spar with the gear up like all my other models.

I am flying mine now with no weight at all so the cg with the gear up is probably 1/4" behind the spar. Granted, mine is the wing tube version but it still should balance in the same location.

I emailed Graemme and I think he said he added 4lbs in the nose and somewhere I beleive I read that Andreas had 4lbs on his, both of these where the folding wing version. Maybe some the other guys will chime in also.

If you get a chance, please weight your plane. From knowing what mine weights, I am guessing you will come in a lot heavier than you think. (you mentioned 45lbs)

Paul

RE: COMP ARF 110
 

I might be out of my league with this but, shouldn't you balance this plane up-side-down? Ive always balanced a low wing plane up side down so that the cg is below the balance point. Still, love what your doing Sam. I can live my life through you and your attention to details.

RE: COMP ARF 110
 

Bob/Paul,
Only 4 lbs, that's not much compared to mine: that's pretty impressive to only need 4 lbs for such a large plane.
Seems like we need to take the worst case scenario which is to balance the plane with the gear up.
You're forgetting that I have all that extra 'hydraulic stuff' which is behind the CG versus a fixed wing.
I also have a dbalsa cockpit which has cast parts plus the sliding canopy.
The tail gear strut is 3/4" diameter so when that rotates back, there's some more weight moved to the rear.
(I believe the tail gear is about 11 oz plus I used air cylinders on the doors and the tail servo is mounted on the tail gear).
I'm going to error on the plus side and put the weight in.
Proportionally, it's not bad compared to my Ziroli P-47. A 96" that weighs in around 36-38 lbs but she flies great. I had to add about 3-4 lbs to the nose to get the CG to balance.
I'm not sure how much credence you can put into the manufacturer's weight: Their 'suggested' weight and mine are always off.

=========================
MODS (fine tuning)

I found another source of flap servo binding: the screws that secure the control horn(along with epoxy) on the outer flaps rub against the side of the inner flaps. A dremel was used to groove out an area along the side of the flap.
The robart tail wheel was going flat so I put some rope foam inside the tire.
Taking the wing off the fuse confirmed my suspicion that the tank moved backward while the engine was running (about 5").
The canopy air valve has to be moved to the side of the main tray as the air tanks on the wing kink the two air lines when the wing is mounted to the fuse.
A weight box was constructed using 3/8" ply at the bottom of the fuse and just behind the fire wall and the former that holds the front of the wing to the fuse.

pic 1/2:
A groove in the side of the inner flaps was needed so the screw heads on the outer flaps don't interfere with each other.

pic 3:
Foam put into tail wheel so it doesn't go 'flat' while in the hanger.
The four screws that hold the outer wings were painted blue.

pic 4:
Tail wheel gear with foam filled tire.
The size of this gear is pretty substantial.

pic 5:
Tank slid back 5" while the engine was running (why we have 'shake down' tests).

pic 6:
Canopy valve will have to be move to the side as the air tanks try to take up the same location!

pic 7:
Weight box made out of 3/8" ply.
A hole was cut in the fuse for easy insertion/removal of weight.

pic 8:
Support blocks for the weight box was epoxied to the fire wall.

pic 9:
Weight floor epoxied in.

pic 10:
weight box needed on my P-47.

RE: COMP ARF 110
 

MODS (fine tuning)

Besides packing up for tomorrows flyin at CORKS, I worked on the weight box.
I used 5 ply plywood for securing the hatch to the fuse.
I epoxied the ply to their respective surfaces.
One end of the hatch will slip into one side and all ply points will be secured using bolts/nuts to insure the hatch never comes off in flight and allowing the weight to fall out!

pic 1:
ply epoxied to fuse.

pic 2:
ply epoxied to one side of hatch.

pic 3:
hex head screws used on the front and back to insure the weight floor never comes loose.

RE: COMP ARF 110
 

MODS (fine tuning)

I used those tough gray mailing bags to hold one large quantity of buckshot but I had to use small heavy duty plastic bags for the rest to get all the buckshot into the weight cavity. The buckshot works nice in plastic bags as it easily conforms to the area and I can remove it if I have too much.

pic 1:
mailing envelope.

pic 2:
heavy duty clear plastic for the rest.

pic 3:
dry fit the cover.

RE: COMP ARF 110
 

MODS (fine tuning)

Definitely the LAST thing for the evening!

pic 1:
Drilled and put 4X40 blind nuts on both sides of the ply to insure nothing comes loose.
The metal 4X40 bolts on the permanent side and the nylon 4X40 bolts to remove the hatch.
I put a layer of the gray envelope material over the bags of buckshot to protect them from the ends of the 4X40 bolts.

The weight is at about as perfect as a spot that I can pick: low and forward, where it's unlikely to jar loose and hit anything.

RE: COMP ARF 110
 

telmaster,
Yep, normal for a low winger is upside down but it's enough of a problem doing it 'right side up' on a plane this size and I don't want to take the chance of damaging the surface on top with all the weight concentrated on one area. If I lean towards the nose heavy, I'll be OK. I can land a nose heavy plane a lot easier than vise versa and then remove excess weight.

RE: COMP ARF 110
 

A few pics from my Corsair on Warbirds over Delaware DVD. I now have a resume. LOL

RE: COMP ARF 110
 

Scott:

Would you be so kind as to tell how you solved your landing gear folding problem? Last we heard, you were going to work with Daryl.

Sam: Graemme Mears had a lot more added items (rear weighted) than yours. Might be worth a phone call. That's why I brought up his name & plane.

RE: COMP ARF 110
 

With virtually, the same plane, they must be using a different CG ( or I'm 'doing it wrong'!).

RE: COMP ARF 110
 

didiwatt, I am living with the gear not retracting all the way into the wing. Darryl was not at WOD this year so I didn't get to discuss it with him first hand. The retracts are otherwise operating well and I have had no issues.

I lost the prime on my hydrolic pump yesterday and had to take the wing off and reprime. Pain!! Hard to unlatch the outer wing panel tto take it off when you can't raise them. After using an L wrench to pull on the cylinder it unlocked and I was able to raise it.

Scott

RE: COMP ARF 110
 

Hey Scott,
thanks for posting the pictures.
I enjoyed talking to you at WOD.

=================
MODS (fine tuning)

I moved the canopy air valve and servo over about two inches to the outside of the tray so the air tanks on the center wing don't hit it.
I can move the fuel tank forward about 4". Besides shortening the amount of fuel line needed to reach the engine (which seems to be important for moki's), this will move some weight forward: When the tank if full, this should help when the gear is up and any lost weight when landing will be more than compensated for when the gear is lowered.
Over on the moki thread, they suggest using header wrap on the exhaust so I bought some online.
Total charge was $23.37 for the header wrap.
Since the 'stuff' that I have on my brass exhaust pipes seems to be working well, I got the same 'stuff' for the header wrap. It's titanium exhaust wrap (DEI-010128) that I got form summit racing equipment.
http://www.summitracing.com/parts/DEI-010128/

pic 1:
new 4"X6" piece of ply epoxied to the front of the main tray for the tank support.
Canopy air valve and servo move over two inches.

pic 2:
titanium exhaust wrap: 1"X15' should be enough.

RE: COMP ARF 110
 

MODS (fine tuning)

I finished up all needed changes:
1) extended main tray 4" in the front to move the tank forward.
2) moved canopy air valve and servo to edge of tray.
3) wrapped exhaust with titanium wrap.
4) replaced defective nav light on/off switch.

pic 1/2:
4"X6" extension epoxied to front of main tray.

pic 3:
Tank secure in new location with a ply 'stopper' plate to prevent the tank from moving backwards.

pic 4:
Battery tray back in.

pic 5:
Twelve new CM-6 spark plugs came in the mail.

pic 6/7:
Wrapped the exhaust with the header wrap.
Used some heavy wire to secure each end.

pic 8:
'Rough' balance test without cowl, prop and gear down: all looks good.

pic 9:
Engine remounted after all other parts attached.

RE: COMP ARF 110
 

Ready to 'taxi, shake down' test.

Tomorrow, I'm going to the field to check for any more 'bugs' plus the 15 mile trip to see if my storage method in the trailer is secure.

pic 1:
All mods complete.

pic 2-4:
secured in the trailer.

pic 5:
prop separate in a blanket.

RE: COMP ARF 110
 

Taxi shake down test.

My camera's battery was dead but, fortunately, Rich was able to take videos and edited it (did a much better job than I would have done, anyway!).

http://www.youtube.com/watch?v=Ex0z3mRdNg4

Engine tach'ing at 800/4050 rpm's.
Since the tank was dry, I used a 'starter' to get fuel into the line and, after it coughed, she started after only about three flips.
The header wrap seems to work: I didn't get the temp gun on the cylinders immediately but the range was 198 (top) to 140 degrees (bottom) plus the wrap protects wires/lines from getting melted.
At home, I sprayed wd-40 on all the rockers and used a tooth brush to clean them up along with the push rods and then put chain saw oil on the tooth brush and coated the rockers and rods. Checked the engine mount and it was tight but all the exhaust nuts needed tightening (the nuts by the cylinder heads were OK). No grease in the 'suction' line next to the hub and all general engine bolts are tight.

The plane seems to 'track' well and all surfaces look good.
It appears that I'm not going to need a lot of power to fly this plane.
A lot of black 'soot' was all over my ankles when 'running' up the engine.
I cleaned up the bottom of the fuse and center wing with 409 cleaning solution. There's not a lot but over time, it would get pretty grungy if not cleaned after each 'outing'.
The minwax clear coat seems to be working well as no paint is on the paper towels or signs of deterioration are showing on the surfaces.

RE: COMP ARF 110
 

Looking and sounding good!!

Good luck on the maiden.

Brian

RE: COMP ARF 110
 

corsair team rodriguez

imc 2010
http://www.youtube.com/watch?v=siQJYigKNsU

RE: COMP ARF 110
 

Good luck Sam! She looks and sounds beautiful. Happy landings.

Scott

RE: COMP ARF 110
 

May the Gods smile on you;),It looks like you got the shake down bugs out. Now its on to the FINE adjustments . Your a better man than I :eek:,seeing your fast taxi on the tarmac I would have been temped to "PUT the COALS to it !!!!:D and get the maiden Test flight without the cowl. Have a GOOD Safe flight.
Semper Fi
Joe

RE: COMP ARF 110
 

Sam good luck buddy on the maiden. NO doubt she'll fly just fine..:)

RE: COMP ARF 110
 

Hey Sam I saw one fly at Wings Of Victory in Woodland, CA 2 weeks a go. All I can say is way over powered. He had the 215 so the 250 must even be more. Saturday he flew around at about 1/3 throttle the engine was not in the power band at all had that lope gurgle type of sound and another pilot had a Radar gun and it was still doing 76 mph on flat flyby's. On Friday he took off and went full throttle and it shot almost straight up and was accellerating had to back it off pretty quick. His didn't have the folding wing though. Very impressive really slowed down on landing I think you are going to be very pleased good luck and looking forward to the maiden.