pettit

My Feedback: (23)

28% comes out to 4.16" behind the leading edge.

25% is 3.714".


25% is just a starting place and is pretty conservative. 30% would probably not be out of the question, but not to start off with.

Yes, stock G-20EI with 4500 maH 4 cell ignition battery placed where they show in the manual. It can be moved forward a bit too.

leedees

gade600sdi, the Higely 4oz hub is a good idea, I plan to use one and paint it too. Especially since I wasted money on a custom TruTurn spinner.

You can epoxy some lead inside the cowl, I have done it successfully but I agree with you, 3/4 of a pound would be excessive.

I think the manual says the CG as far back as 28% has been tested successfully. I am probably going to end up somewhere in the middle.

I must be unlucky with CG, last year I built a H9 P-47 Thunderbolt with .115 Saito that needed a pound of lead up front while other guys with the exact same setup needed nothing. The good news is it flies great.

leedees

Now I'm pissed off.

This is a very expensive ARF from Hangar 9.

I'm using Zenoah G20 and every other part exactly as spec'd by Hangar 9 and the CG is so far back it will now take at least a pound of lead, somehow mounted on the front of this thing to make it airworthy.

The big 4500 battery won't fit anywhere except on the cabin floorboard and even the 2700 receiver battery won't fit in the forward battery compartment next to the gas tank.

This thing will be so heavy I'll need a 2000' runway to take off and land.

They should send some guys out to Aeroworks in Colorado so they can learn how to properly build an airplane.

pettit

My Feedback: (23)

Interesting. I followed the manual 100% and both of my batteries (2400 maH 5 cell and 4500 maH 4 cell) fit exactly where they show in the book.

I even relocated the ignition battery more forward next to the tank on the pilot's left side and brought the balance point within range of the 25% point.

leedees

pettit, I'm glad to hear the CG on yours is so much nearer where it needs to be.

Yes, my JR 4500 ignition battery fits just where shown in the manual, under the floorboard. It will not fit in the horizontal location against the firewall next to the tank, you can't even get it in there.

I needed 3/4 pound of lead to balance even with the 2700 battery laid up there horizontal next to the tank. It didn't quite fit in there as it hit the firewall before clearing the former. I've put the batteries back under the floorboard and will pile on the lead and epoxy until she balances.

Rudolph Hart

Agreed about putting that much weight that far out front,but it would sure make an ugly looking spinner/prop nut on a scale bird like this,it's classy looking.I think you are in denialit needs a heavy good sounding fourstroke in it and tail draggers fly very well when the wing loading goes up,specially when it's windy.Cheers

gade600sdi

Leedees, last night I checked there is room for both battery packs beside the tank. If you install them first with your hand through the fuel tank hole then push them over on each side and then lastly put the tank in you can do it with ease...I put a 4500 pack in this morning with no trouble at all and I have pretty big hands. This will go a long way vs. having it under the floorboards becasue that 4500 ignition pack is heavy moving it forward 6 inches should help you alot.

Also, the Higley heavy hub is only available in 2 oz size with what I can see with the crank threads on the Zenoah. They make a 4 ounce ultra heavy hub but biggest is 5/16-24 thread and it wont work on the zenoah.

leedees

Yes sir, I have consoled myself with the fact a higher wing loading is an advantage during those windy winters we have in south Florida, maybe I'll look like a better pilot!

You're spot on, I think one of my Saito's would have been a better choice on this good looking airplane. At least I could put on a spinner without cutting off the engine's prop shaft. I'll have to pretty up the prop hub with some white paint. I ended up getting three oz. in front of the prop that way. Did I mention I am unhappy with TruTurn? :-)

The only advantage I can see with the gas engine on this size airframe is the cheaper fuel, otherwise they seem to present more issues than a four stroke glow and way more issues than a two stroke glow.

KDawg

leedees,
I have purchased this aircraft as well and like you and others I was planning on setting it up with the Zenoah 20ei and all the stock recommendations from Hangar 9. If there is that much of a balancing issue do you know if anyone on this forum has contacted Hangar 9 to see how theirs was actually set up? and did they have to do anything special to be within CG? The one they show on their website with the video of it flying seems to do quite well.

leedees

KDawg,

I haven't contacted Hangar 9 and haven't read any report of anyone speaking with them about the CG.

I think the problem is common among many ARF's. As you know, your particular airplane might balance beautifully with the stock setup and require only slight adjustments. I think Pettit said he only put 6 oz. in the nose to balance at about 28% (4.17") on the CG but he's probably a better pilot than me. You just never know until you get it built but it does appear many of them will require some weight in the nose. I am just grumbling because I expected a little more consistency on this ARF.

It will fly just great even with the lead ballast, just more work to finish it is all.

I mentioned earlier I built a H9 65" Thunderbolt that took a pound of lead to balance while other guy's identical setups took nothing. It is one of the sweetest flying airplanes I have. I joke that the Chinese guy that built it used oak stringers in the fuse that day.

Not having experience with gas engines, I probably would choose a glow engine if doing it again.

leedees

gade600sdi, that's a great solution to getting the batteries in there, wish I would have known of your solution. I never even considered removing the tank to get in there. Maybe when I get older I'll be better at this.

I was able to get about 3oz in front of the prop using a Higley brass lock nut with the heavy hub. Hopefully it will look OK with some white paint on it. I'll post a pic when finished.

gade600sdi

My G20ei came in last night. I mounted it on the firewall quickly and threw my batteries in and hung the ignition box cowl and prop on the front to get a quick balance reading. It is going to be tail heavy! Not sure how much yet, I need to get it all assembled but I am definately putting the batteries up front beside the tank to get the most out of that. I hope I dont have to add too much weight when its all over. I am thinking of scrapping the seat and the pilot possibly too to save a little weight they feel like 6 ounces I can do without.

GBR2

My Feedback: (1)

Regarding the Tru-turn Spinner. I bought one of their prop hubs for my Clipped Wing Monocoupe that has a G26 in it. As others have found, due to the length of the prop shaft, it did not work. I did get to talk to one of the "techs" there and they know their stuff doesn't work with the G26 (and obviously the G20) without the prop shaft being cut down. What I don't understand is why don't they tell you that up front on their webpage where I ordered from.

The good thing about the G26 and probably the G20, is that the prop shaft is really a prop stud. It can be removed and replaced. Tru-Turn did offer to cut the 2 extra prop studs I had down to proper size for free, so I did have them do it. I haven't replaced the stud in the engine as yet as I had my share of futzing with the engine, cowl, etc. when tweaking everything so it all worked correctly. So I'm flying the plane with just the prop nut that came with the engine but the plane will certainly look better with the hub if I ever get around to replacing the prop stud.

Parks

My Feedback: (9)

GBR2,how about a picture or two? Thanks for the info.

leedees

Completed the build and ended up with a dry weight of 15 pounds. Specs call for 14-15.5 pounds, so the 1 pound 2 oz of weight added up front shouldn't be an issue at all.

There is so much lead screwed and glued to the firewall the pilot is totally insulated from x-rays! I got about 3oz in front of the prop by foregoing the TruTurn spinner that didn't fit and using a Higley Hub and lock nut. It doesn't look as good as a nice spinner but it's not too bad.

I think the only way you could hit 14 pounds is if you powered it with rubber bands.

pettit

My Feedback: (23)

Hangar 9 must have switched horses in mid-stream. The instruction manual and the box cover both say "13 to 14.5 pounds", and so did the web site listing, up until a few days ago.

It now says "14 to 15.5 pounds".

Mine weighs 14 pounds 11 ounces with absolutely zero added weight to balance at the 28% point.

leedees

Dick, good observation. I checked the website for the weight spec a few minutes ago and thought I was mistaken as I had it in my mind this was a 14 pound airplane.

It's funny how much difference in weight there is between our two airframes. I am balancing at 25%.

Lee

leedees

GBR2, that's my beef with TruTurn as well. They should respect my time and money and tell me when their spinner isn't going to fit without more expense and work on my part. I may eventually get another prop stud and cut it down but in the meantime I'm ok with my painted Higley hub.

Thanks for the info.

pettit

My Feedback: (23)

A Dremel tool and a HDcut-off wheel and about 30 seconds and Ihave the correct length prop stud.

My TTspinner fits most of the props I plan to use but I had to ask for the "120 cut" when Iordered it.

gade600sdi

Leedees, it looks good. I count about 36 segments of lead, or 9 ounces from what I can see in the picture. Plus 3 ounces in front of your prop = 12 ounces. How did you come up with 1 lb 2 oz which is 18 ounces...where is the other 6 ounces?

gade600sdi

Leedees, it looks like you put foam on either side of the ignition box on the two long sides and then left an air space in the middle for cooling, is that right

leedees

There's two more ounces not visible on the firewall behind the engine and four ounces epoxied inside the front of the cowling. Putting the lead in the cowling was a tight fit to clear the muffler, I had to chisel a little bit away for clearance.

leedees

Yes, but the middle space doesn't run full length, I just cut the foam about a third away from the top and bottom. The pictures in the H9 manual are not real clear. The H9 manual is pretty clear when it says to put 1/4" foam behind the ignition.

The conflicting information is from the Zenoah manual that says there has to be airspace behind the ignition. My solution of cutting away some of the foam in the middle was a compromise solution that hopefully doesn't result in my engine stopping (or the airplane catching on fire!) I'll keep an eye on the situation during the preliminary engine runs.

I asked how hot the ignition gets with respect to the fuel line touching it in another post on the gas engine forum and the replies were not definitive.

Dick Pettit is using a C&H ignition that draws less current and presumably runs cooler.

One of the guys did recommend this thread for gasser noobs : http://www.rcuniverse.com/forum/m_8673009/tm.htm

The author sounds like everything that could go wrong, did. Some useful info however.

mobyal

Well, finished up engine (OS120AX) installation today. Wound up w/ 1/4" ply spacer behind the OS metal mount. Throttle servo all hooked up, and battery (8.5 oz worth) mounted on the firewall. Waiting for the muffler; it's on backorder from JTec. Brisson makes one, but they're on backorder too. Installed the main gear, and I have to say that I think it's the easiest gear install I've ever done. Even the wheel pants were a piece of cake. It'll be the weekend before I can get back in the shop, but then I'll do the tailwheel, tail braces and the wing struts. Then all that's left'll be the muffler, receiver and setup. Still not sure whether I'll use 2.4/Spectrum, which is new tech for me, or the tried and true 72. THEN we'll see how it balances. I weighed the tail braces stuff and tailwheel today. Right at 3.5 oz. If we use the "4 to 1" formula, that means it'll take 14oz up front to balance that out. Be interesting to see how it all works out.
Al

fabmaster911

Maybe you can get Jtec to make the muffler out of lead. I always figured if I needed weight in the nose I might as well put in a bigger engine hence the DLE baby.