Rich

Thanks for the excellant info. I understand that planes tend to climb with higher power settings, this just seems a lot more than any other plane I have had, all of which I overpower.

I will definatly try your test next time out.

Question though, assumung the downthrust is about right based on your test, what would you suggest to remedy the problem? I can just continue to add down elevator on full power, or I can use a curve mix to do it automatically, or I can trim the plane for full speed and deal with it at mid range.

I know my CG is back close to the edge. But it is manageable. Mike McConville (TOC) was at our field today and flew it and didn;t think the CG was that far back. I do notice a tendancy to billow when flaring for landing if not careful, but did some slow snap rolls today the plane recovered easily. Do you think moving it forward will help any?

JWortner,

I'd say trim the plane in a manner that suits your flying style.

In full scale aviation a good pilot will always trim out the pitch forces everytime the aircraft configuration is changed. In small general aviation aircraft like a Cessna 172 you could probably get away with not retrimming in most situations. Move up to a Cessna 210 and you HAVE to retrim or you'll wear yourself out at a minimum, possibly damage the plane during landing if you don't retrim.

In models we don't have to deal with the actual control forces so retrimming isn't ordinarily done. If you don't fly around at full throttle, I'd trim the plane for hands off level flight at whatever lesser throttle setting you prefer. Then do as you've suggested for full throttle, roll in some mix to compensate.

From your flight experiences so far, it seems the RB has a fairly wide CG range. However the fact that you have some pitch sensitivity in the flair during landing indicates that you should probably move the CG slightly forward. Or you could use a little expo to decrease the sensitivity of the elevator with low stick movement.

Rich

New development on the RB. Anyone have any concerns about the way the wings mount? I got looking at it the other day and I realized the the wing rod retaining screw does not go all the way threw the rod. I noticed this when I had the rod out and tried to thread the screw into the rod for safe keeping, it only screwed in a little bit before hitting significant resistance. In other words, the hole was not big enough for the screw to pass through. I check the other side and had the same results. My first reaction was to head out and find a longer screw, but did'nt get a chance to do it because we were heading to the field that morning.

That same day the RB had flights 5 and 6. We ran it pretty hard. The tail held up real good. I tried some medium some snaps and spins and was VERY surprised how quick the RB locks up straight when recovering from maneuvers without requiring any control input. I mean you get into a good spin and just neutralize controls and she locked straight up. Pretty impressive, I would have expect it to be more snappy.

Well, back to them of this story. At the end of the flight, I noticed a significant gap between the wing and the fuselage, probably about 1/16!QUOT! and you could sort of wiggle the wing a little bit. I took the wing retaining screws out and went to remove the wings and they were STUCK! Both of them would not slide off the tube. GO figure......

They would come off about 1/4!QUOT! or so and then hit resistance. I could push them back together, but they would hit something when pulling them apart. Finally after some significant wiggling and pulling we (it took two of us) got them apart. Couldn't really see anything wrong. I suspect that a bur developed where the screw goes threw the rod which was hitting something keeping the tubes from sliding out. I expected to see the holes in the wing tube to be elongated, but they did not look that way??????? Something had to give for the play in to wings to appear.

Anyway, as I mentioned earlier Mike McConville (TOC) was at our field today. He designs most the the Hanger 9 planes now so knows a good deal about building. He said that he stopped using the screw through the wingrod some time ago because of the same problem I just explained.

Sooooo, the next new mod for my RB is to fab some wing bolts to hold the wing to the fuselage.

In a earlier post the wing attachment was a concern and addressed. Some guys are using a method like is on the H9 Funtana 90 (plastic bolt from inside the fuse to a threaded block or insert in the 1st wing rib) Just a thought. Skip

I was leary of how the wings where mounted when I first saw the method... ... You;ll have to scroll back to the pages when I was putting mine together.... back around page 10ish I think...I took some pictures and posted them... Anyhow..it all works just like Funtana 90.. Can be a little tricky the first few times getting the bolts in, but after you figure out hot to contort your hand, and the use of one of those ratcheting box-end wrenches (can you say Harbor Freight), It's takes no time at all.... and far more rugged.

Steve
I am aware that one of the Bear's at Ace lost a stab due to flutter. I realize that it had a 120 2c in it but that should not be a serious stretch in power over the recommended 90 2c. I had a YS-91 in mine turning a 14x7 3-blade, which is just right for the engine. I even took the lower skin off the stabs to make sure the rods were seated and added glue to all the joints. There is a design flaw with the system. Either with the stab attachment or the push rod or both. You should not have to change components from those supplied to make a relaible bird. Especially, when paying that price.
Dan

To fix the gap between wing and fuse how about this-
I want to add white epoxy to the wing to fill the space against the fuse. I would put plastic wrap over the fuse where the wing seats then roughen the wing where it goes against the fuse and apply white epoxy to the wing and push it against the fuse where I put plastic wrap on it. After it set I would trim the epoxy and cover with white Ultrakote.
I think it would work, but would it be ok strength wise?

sj crash- Yours went in even after modifying the stab?

^^^^^
I'm wondering the same thing there Sj-crash.

Yeh, me too. Did you crash? What kind of power did you have in it? I have only flown mine twice since I beefed up the stab but it showns no signs of weakening. Now my wings on the other hand were all types of loose. Just made wing bolts last night to take care of that! I would STRONGLY suggest that to everyone too.

JWORTNER
I HAVE ANOTHER RB AND THIS TIME I BEEF THE STAB I'M GOING TO TAKE YOU ADVICE ON THE WINGS DO YOU HAVE ANY PICTURES?

Pajaro,

I will take some tonight and post them. Did you buy a new RB or did ACE replace it????? Is it brand new? If so, don't forget to glue the engine cowling mounting blocks in first. Save yourself a world of grief

JWORTNER
yes it's brand new, but no they did not replace it when i talked to anthony first he told me that
the only thing he could do was give me dealer price i accepted and order it.
two weeks after i call them asking for my rb and anthony told me he didn,t know anything about it ,and he would need the receipt wich i fax it to he'm sence the first day.
so i think they don't want to know anithing about it ,i just gived up. to me rb it 's a beatiful airplane so i deside to buy another one and try one last time.
ps. i will do the cowling mounting blocks. thankyou

Mine went in on the second flight. It flew great I did a few loops and low passes and on the fatal pass I had reduced power to about 3/4 throttle. As I exited a gentle descending turn to line up with the runway the model rolled twice and then headed for the ground. A post mortum showed that the right stab trailing edge had split along the hinge line opening the stab up hence it departed giving a rolling moment. It is my understanding that the failure Ace experienced was similar. I am waiting for them to examine the parts. My recommendation is to place carbon fiber tube in the stab to slide the rods into. Also either replace the TE with hardwood or carbon fiber reinforce it. Also, replace the elevator push rod setup with a arrow shaft and 4-40 size wire. The plane is a great flier and I hope that the manufacturer corrects the problems. I would not buy another one until this happens as you shouldn't have to pay more to do their job. If Ace replaces the model I would be extremely happy to modify it as described

Pajaro,

Here is the pic of the wing bolt mod I did. Probably similiar to the one mentioned by Highsierra back around page 10-13.

Notice the actual wing bolt. I used a belt sander to sand the threads off the beginning of the bolt. This allows you to more easily stick the bolt in place and start threading it in.

I would definatly recoomend this mode to everyone. Fly this weekend and my wings remained nice and tight.

Jwortner I was just wondering about the Futaba S3004 standard BB servos for the elevator in your post. Then on second thought maybe with all the stab problems you don't want a strong fast servo on the elevator It could really put some force on the stab.

Don B

Don,

Yes, that servo made me nervous. I have since replaced it with a Hitec high torch metal geared servo which I mounted in the rear of the tail as shown in previous posts. As far as strong and fast servo's, the throw required is only 3/8 on low and 5/8 on high. I have never even tried my high rate. Even on low I have plenty of authority, even when slow. I used the inermost hole on the sero and the outermost hole on the elevator arm to get the best mechanical advantage I could.

JWORTNER
what engine are you using on your rb ?
and thaks for the tip on the wings, definatli I will do the same thing before I fly it next weekend.

Pajara,

I have an OS 160 2stroke. I am running a 16x8 3 blade. Just tried a 16x10 and I was not getting good RPM, have to try tunning a little, but may go back to the 16x8. I was noticably faster with the 8 pitch.

Don,

I don't believe a "Strong, Fast servo" would be a cause for worry. Sure there would be an instanteous increase in horizontal stabilizer load when the elevator is deflected. This instantaneous load will then equilibrate to a constant load until the elevator position is again changed.

The key issue with the RB stab is the poor build quality, mainly lack of glue and insufficient material in certain areas. When I was modifying my horizontal stabs and elevators for Robart Hinge Points, I found the trailing edge of the horizontal stab and the leading edge of the elevators to be manufactured with very thin stock, maybe 4mm thick. It's so thin there's insufficient material to drill and pin regular hinges. This is also true in the areas that receive the elevator torque rods. The other manufacturing flaw that may be contributing to the stab failures is the manner in which the slots for the CA Hinges are cut. The slits are excessively long and cut through the trailing / leading edges into the ribs. At the tips of the tail surfaces this probably isn't a issue, however at the torque rod end it is. I found the rib which supports for the rear tube spars split from the trailing edge all the way through to the hole for the tubular spar. If the builder isn't careful and doesn't adequetely glue the tubular spar and the ribs, also filling the split made during manufacture, failure of the horizontal stab is highly probable.

FWIW: I'll be installing dual Futaba metal geared, coreless mini-servos very near the elevators, with individual control rods to each elevator. Although this mod adds some tail weight I have full redundancy in the event of a servo failure. If I'm unlucky and have the classic RB tail failure, this feature might also allow me to get the RB back on the ground in a semi controlled fashion if only one side fails in a manner which doesn't prevent controlled flight.

Rich

WORTNER
I DID THE BOLTS ON THE WINGS, ONCE I WAS DONE I WAS VERY HAPPY, THEY MAKE A LOT DIFFERENCE,NOW I DON'T THING THOSE WINGS AREN'T GOING ANYWHERE. I'LL
FLY IT THIS WEEKEND SO I'LL LET YOU KNOW WHAT HAPPENED,THANKS FOR YOUR HELP.

Pajaro,

Waiting to here a report on how things went for you. You indicated that you had your new RB ready to go. I hope no news is good news.....

Ok, what do you guys think about an OS 120 Suprass with a pump in this bird? Could it fly it good or do you need something bigger. Also, what seems to be the consesus on fixing the retracts? I just bought the H9 Miss America after reading the article and saw that he just bored out the hole in the retract unit and put bigger wire in there.

Make that a YS 1.10. Cheaper, lighter, and no doubt more powerful...

jwortner
ok. i have good news.