A friend of mine called and said that he was trying to balance his plane
All the info he was able to give me was it is a bipe and the wing span is about 54 inches.
the plane weighs 10lbs without the motor which he got from me about 3 weeks ago
The motor is a saito 150 I know it weighs 30oz without spinner or prop.
He was saying that it will take 1 3/4 lbs in order to get the cg ???
Since I have never had to use that much weight before I could not answer his question with out seeing the airplane.
He says that he is balancing it correctly any ideas because I am sure lost on this one
Would this amount of weight be ok it seams like way to much to me

If you have to add 5 pounds, then it takes 5 pounds to get the CG right. I have had to put more than a pound in several planes and the plane doesn't care.

Boeing F4B-2, came in at 12 pounds complete. I used sub C 6 volt battery pack behind the fire wall, all controls as far forward as they would go. Required just over 3 pounds of lead in the cowl to CG correctly. So, it was now almost 16 pounds. I still have the plane, it did fly scale except it wouldn't loop without a dive. It is a slug and it's great trick is the stall turn, all it wants to do is fall out of the sky. Landing is really easy though. Take off and landing are really scale looking.
Any plane that had a radial engine was short coupled because of the engines weight so you will know before building it's going to be way tail heavy so you have to compensate during the build. I didn't!! I sent the plans to a friend and his came in at 12 pounds and is an outstanding plane in the air. Before the build I let him know the problems so he was able to think ahead.
How much lead?? As much as it takes. This plane is a 68 incher and you heard me groaning when I had to lift it. It's just a wall hanger these days unless I need something to fly at an IMAA event.

If you have to add 5 pounds, then it takes 5 pounds to get the CG right. I have had to put more than a pound in several planes and the plane doesn't care. 
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 Thanks minnflyer I could not answer his question because I have never had to use that much weight before
Just lucky I guess I have always been able to get the cg by moving the batterys and  using way less then a pound of weight.
It just seemed to me to be quit a lot .
I'll give him a call and let him know since I wont see him for anouther couple of weeks.
He lives in fla and gas is way to expencive to run down there just to take a look at what he's got.

If it a shorter nosed bipe like a Sopwith Camel then that could be accurate. As far as, is that too much, what is the upper weight limit on the kit? If you are too much past that then you may want to consider moving some gear. Putting the battery in the cowl works well. Just build a fuel proof box to put it in, preferably above the engine or opposite the exhaust.

Nice plane gray beard Good to know that I have just been lucky it looks like I have never had to add that much before so I couldn't give him an answer.
I guess I also dont try to stick to big of a motor on one either hehe

Thaks for all the replys I guess I have learned something tonight

[quote][If it a shorter nosed bipe like a Sopwith Camel then that could be accurate. As far as, is that too much, what is the upper weight limit on the kit? If you are too much past that then you may want to consider moving some gear. Putting the <font color="#000000">battery</font> in the cowl works well. Just build a fuel proof box to put it in, preferably above the engine or opposite the exhaust. <span class="info"></span>
/quote]

cfircav8r

Not sure I will have to get more info when I call him.
I will have to pass along the battery box suggestion .
Thanks again

Bill

Is he trying to set the CG without the engine? The wording of your question leaves this open. If that's the case, then the engine will bring it in close to balance. It might even need an ounce or two in the tail.

Movine gear forward helps but like in my case, there wasn't anything else to move. I made my own cowl and it is really thick glass and very heavy. That helped but wasn't the total cure. The three pounds of lead had to get set into the cowl qith epoxy. Last year I was looking at that Boeing and decided I could put a 40cc gas engine up front and remove all the lead. That didn't work out too well and I had to still add lead. I went from an OS 1.20 pumper to a Brison 2.4. I would have thought the added power would make a better flying plane too, nope, it was still a slug.
Hind site being 20/20 today I would have built the plane with the nose of the fuse extended, a lot!! Then I would assemble the plane complete without the covering and have the engine mounted to the fire wall and then set the plane up on the CG machine. Tack the engine/fire wall to the fuse and keep moving it forward until I got the CG. Mount the fire wall in that area, cut the fuse at the fire wall. Not 100% scale but other then myself who would notice. The nose moment would be a few inches longer then it should be.
There are things you can work around. That plane would be better with ailerons top and bottom too. The full scale had small ones on the top wing anyhow so it isn't scale anyway.
It was a fun build, plans by John Tanzer, at 12 pounds it would be a killer machine!!

dredhea

No he was talking with the 150 installed, spinner and prop.
That was the first question that I asked him.
found out that it is a Sopwith Camel still dont know whos kit or if it was built from plans.
He made mention that the plane is supposed to weigh in around 8 to 10lbs with a 60 to 90 2 stroke.
I was a bit concerned about the 1 3/4 lbs he was going to add to the nose of the fuse the plane will weigh almost 15lbs when he is done.
He seems to think that there wont be any issues.
Then I had to ask why were you calling if you didn't think that there would be a issue[:@]
Again thanks for the replys

Bill

A WW1 biplane with a 54" wingspan weighing 15 lbs.? That should be interesting, and not in a good way.

I added almost two pounds to a Tiger 120 a couple years ago and thought that was WAY to much..but it needed it to make the correct CG.

But as I found out, the plane did not care at all. It flew like all Goldberg Tiger series aircraft.. it flew just great. A fun plane to fly, in fact, and very capable as well as very visible. No probems at all with that added weight.

CGr.

It may fly very scale but more likely it will need to be flown fast and have a very small speed range between stall and max.

I agree. I'm building a 1/4 scale pup (77" wingspan) with a G-26 in the nose and I'm anticipating about 15 lbs flying weight. I would actually like to lose a pound or two, but I don't see a way to get there.

I recently read an article about a .60 Sopwith RTF where the instructions CALLED for 1.5 lbs of lead on the nose. The ARF comes with a wooden box that is to be mounted just behind the upper part of the engine box.

Given that he's using a light engine to begin with, the amount of weight he is talking about may be spot on.

Make sure he's measuring for the C.G. correctly. Top Wing center?

See here: > [link=http://www.rcuniverse.com/magazine/article_display.cfm?article_id=810]Click me![/link]

Scroll down where it talks about the weight box for the nose...

Two differents approachs, three different airplanes[8D]

What? The Tiger 120? It flys just as slow as you can imagine a Tiger 120 with that type of wing loading. It pretty much floats in. Very doscile. It's not a scale plane. It's just a large Goldberg Tiger. I've NEVER been able to stall it, and I can say that I've tried. Those two pounds just don't matter with that plane.

CGr.

There are always weight that can be taken off the tail. Remember in most cases 4oz OUT of the tail is equal to a full pound in the nose.

I thought the same thing... It's the weight of a much bigger plane... (Stall speed 74 mph, max speed 76 mph)

I would make video the maiden just in case. On the other hand, no matter what the weight, the CG hast to be in the correct place, otherwise, it will be tail heavy and short lived...

Gerry

John, I really like the battery box idea. Noet time I set up the old bipe I will give that a try. My pack was inside the plane mounted to the fire wall but that could be a big weight saver. Next engine I try in the Boeing will be an RCS 1.40 so I could set up the flight pack on one side and the ignition pack on the other. Thanks for the photos.

I think he was referring to the Sopwith, but you're right, not all heavy planes need a ton of speed to fly. I have a .60 size Eindecker with an old Magnum 60 4-stroke. Even with an extra 14 oz. in the nose, it still flys great at around half throttle

Bill,

There should be some local experienced pilot that can help your friend in Florida.
He could post his location here, or try to find RCU members in his area and contact them.

Those early planes had a short nose in order to balance the huge and heavy engines of the time.
As a rule, the shorter the nose, the more weight ahead of the CG is needed to balance and vice-versa.

Can you explain at what point of the wing is he balancing? Top or bottom wing?

The battery box next to the engine is a novel approach. I am concerned that apparently you are not isolating the battery from vibration in the box. In the cantilevered box, next to the 2-stroke engine, vibration could be quite severe. I would feel safer with the box sized so as to allow wrapping the battery with foam. Then, one should protect the foam and battery from oil soaking.

The four cell battery weighs about four ounces. If you move it to its "normal" location behind the firewall, you would only have to add an ounce or two at the front of the firewall to compensate. All in all, with the increased risk for the battery, probably not worth doing for most applications.

I would also advise not mounting weights to a plastic or glass cowl in most cases. I have seen this cause cracks at the cowl mounting screws. It is safer to mount weights only to the firewall or possibly to the bottom of the engine mount. I have used long engine mount bolts on occasion, then mounted steel, iron, or lead weights to the bottom of the screws with another set of nuts. nc

I also no longer rely on stick-on weights (auto wheel weights.) The foam adhesive on these is NOT fuel proof in the long run, and these weights invariably fall out! My new favorite method is to cast my own lead weights in a small wooden mold, about 1 1/4 inch square x 1/2 inch high. This mold will produce a maximum weight of about 3.5 oz. I can stack these if needed, or cast a shallower one if less weight is needed. I drill one hole through the center of these lead coupons and hold in place with a 1/4-20 bolt through the firewall. You can tap the hole in the firewall or use a blind nut. Neat!

littlera

Lnewqban

I wish I could give you some more info I talked to his wife today and he will be on the road for the next couple of weeks.
He is a p<span style="LINE-HEIGHT: 115%; FONT-FAMILY: "Calibri","sans-serif"; FONT-SIZE: 11pt; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-hansi-theme-font: minor-latin; mso-bidi-font-family: 'Times New Roman'; mso-bidi-theme-font: minor-bidi; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA">rofessional stearing wheel holder most of the time ( truck driver ) so I'll have to wait until he gets back to talk to him again.
His wife told me that he might get a chance to swing by and see me first of next week so if he does I'll find out and post what I know then.
Thanks again for all the replys and the great suggestions and pic's there are a lot of good ideas that I can pass on to him the next time I see him.
Like told him personally I have never had this issue before maybe just luck or maybe because I take my time and think thru my builds either way I knew I wasn't able to answer his question about the weight.
Thanks again

Bill</span></p>

i always use the more forward (factory)CG to start off with, and make sure its slightly nose heavy from there to play it safe....... id rather have a nose heavy maiden flight when compared to a tail heavy maiden flight on a windy day.