I_Fly_Coolers

My Feedback: (7)

After 6 months of rebuilding my WW1 Junkers Monoplane, I attempted the re-maiden on monday with a very scary result!! After taking off, climbing to 30 feet, the plane would not gain altitude. It was mushing along tail-down on the verge of a stall. After calming my nerves I made a slow turn away from the trees and landed it sucessfully 30 feet away from me. Before the crash, it flew great, had about 7 flights on it but lost it to a dead stick in a bad spot. I know the plane gained about 2 pounds after the rebuild- I used a larger battery pack, added a servo and used a heavier wing tube. Dry weight is 21 lbs. Using a Zinger pro 20x8 prop. I also run white gas/camper fuel in it. I suspect the fuel has lost some of it's potency from sitting 6 mos. The engine does not start as easy as before. Local Wal-Marts have been wiped out of camper fuel because of the hurricanes here, so I couldn't get fresh fuel before the maiden. Only other thing changed is that I used to fly it with a Top Flite 20x8 prop before. Full throttle on the ground we tached the engine at 6800 RPM, which I believe to be normal. Airplane has a semi-symm. airfoil, not flat bottom. Could old fuel npt be producing enough "power" once the prop is loaded in flight? Should the US 41 be able to fly a 22 pound airplane? It's no aerobat, just needs to fly!!

Antique

My Feedback: (4)

The carb might need rebuilding, and you could tach it without the muffler and maybe gain a little....Pretty heavy for a US 41...Some have said a WA144 carbfrom a Q52 improves it, I tried one once and found no gain...

I_Fly_Coolers

My Feedback: (7)

hmm... The engine was sent to bennetbuilt after the crash for a checkout, and carb adjust- Seemed to be OK to them. I will try to locate some fresh fuel before this weekend, will run pump gas if I have to.

excaliber

Coleman fuel or white gas does not have the same punch as gasolene. In my opinion the plane is a little too heavy. Did you check to see if all the incidences are what they are supposed to be before your incident. Check the horizontal as well as the wing.

I_Fly_Coolers

My Feedback: (7)

Thanks for the idea I will check the incidences tomorrow.

Antique

My Feedback: (4)

I had a 12 foot Telemaster, 19 lbs, G38/20-8 Zinger power...Flew SLOW, took a big dive to do a loop.....

H. Wayne S

My Feedback: (18)

Ah, Flying on the wing, the "good ol days".

Dr1Driver

That plane should fly on the wing, as mentioned, and the 41 should be enough engine to fly it in a scale-like manner. Switch to regular gasoline, there's no benefit from running what the engine isn't designed to run. Clean the carb and check the filters in your fueling lines. The prop doesn't Load" in flight, it actually unloads, and flight RPMs should be a little higher than static on the ground.

Dr.1

BillS

My experience indicates that a 41cc engine should pull a 22-pound airplane very adequately. As you already know it will be flying on the wing. Fuel is not likely to be the problem if the engine is turning 6800 RPM.

The questions:
1. Did the engine turn 6800 RPM before and after rebuild?
2. Did the airplane balance properly after rebuild?
3. Did rebuild change the wing or stabilizer incidence?

I damaged a big heavy gas airplane once because the throttle barrel was not opening to full. The engine sounded like it was running full throttle but the carb barrel was not full open. The engine sound was deceiving. Also part of your description might indicate that you may be flying tail heavy.

Bill

PS: I thought the engine was running at full throttle but it was only about 5/8 throttle.

Edwin

My Feedback: (2)

I agree with the previous 2 replys. I have a BT Corsair (75" ws) that weighed in at a little over 20 lbs and flew with a US41. Had absolutely no problem at all. I was terrified it was gonna be a led sled but the maiden went very well. Take off was perfect, flew good slow and had respectable speed. The only problem was my landing, ran out of runway cause I was just to fixated on it as it floated by. I got to control myself better when flying, I just love to look at the planes as they go by. Realized a little too late that I was 3/4 down the runway after I set down. DOH!! A US41 should handle that plane with no problem.
Edwin

Edwin

My Feedback: (2)

One other thing. I ran a 18x6-10 prop. Seemed to like it a lot.
Edwin

I_Fly_Coolers

My Feedback: (7)

I found the stab at 1 degree postive incidence. Never checked it before the crash. The plane is built from MAN plans, no reference to incidence on the plans. Bill S- you may be on to something, first thing I though after takeoff was "tailheavy" I don't have much experience with large scale planes, I know the smaller planes when tail heavy will still fly but will be
over-sensitive to elevator input. I did, during the rebuild remove 1 lb of lead from the nose that the previous builder had installed- did not know what engine was in it, but I remeber the plane balanced "nose heavy" according to the recommended CG before the crash. I could not remove the weight because it was epoxied in place, I replaced the weight with 10 ozs after the rebuild, which put the CG right on the money- but it flew fine before being nose-heavy. Perhaps the recommended CG is not correct- very possible since the forward bulkheads drawn on the plans were 3/4" too short, and they say this plane should weigh 17 lbs- no way!!! It is a naturally tail-heavy plane as you can see. I will rebalance it with the CG forward (add back 6 ozs to the nose) and give it a shot this weekend, also I will double check the throttle butterfly opening 100% Pump gas is a last resort as I store this plane on the ceiling in my 2 bedroom duplex, would definetly stink up the place. Thanks so far for all the input!!!

PT21Flyer

My Feedback: (1)

My Bridi Big Bee flies great at 20 lbs. on a US41. I'm using a M/A Classic 18-10 but it also flies good on a 20-8 just slower. It will loop from level flight at half throttle.

Jerry

I_Fly_Coolers

My Feedback: (7)

Finally had a chance to fly the Junkers again. Went to the RC World Fly-in here in Orlando, and, as it turns out, Dick Allen, the original designer of the plane was there!!! He was so excited to see one of his plans-built planes there, and I was equally as surprised to meet him!!! Anyhow, his original did come out around 17 lbs, he didn't know why mine was so heavy, neither do I. Anyway, I added 12 more ounces to the nose for balance, had the verteran test pilot fly it, he made one pass around the field and made a perfect landing. It was windy today- He said on a calm day it would be "ok" but it sure looked pretty scary today- upwind it climbed out pretty good, but downwind it struggled to maintain altitude. I spoke with Dick Allen and he said I might be happier with a G62 in it. I wouldn't be adding weight as I can remove the lead, but I should have power to spare. Also got a couple coments about how it seemed a little rich on the top end. Only option other than the G62 would be to try the 18x10 prop, and lean it a bit- which scares me because that's why it deadsticked last time and stalled. Any comments? Thanks!!

tommy157

My Feedback: (1)

Go with the G62, you will love it and have plenty of power

I_Fly_Coolers

My Feedback: (7)

Thanks. Looking around now for a decent used G62.

chuck l

My Feedback: (17)

I_Fly_Coolers,

You might want to look into this Ebay sale. The guy might still have some and you could send him an email. Also, there is another one for sale on Ebay that you can find by doing a search on G62 and Zenoah.

http://www.rcuniverse.com/forum/m_35...tm.htm#3586691

Chuck

I_Fly_Coolers

My Feedback: (7)

Thanks Chuck, I am watching a couple on ebay. Do you guys think a Quadra 50 will have enough power? I find they are a bit cheaper, but more importantly the carb is on the same side as my US 41, so I won't have to modify the nose of my plane like with a g62. Looks like they mostly come with a spring starter already installed.

I_Fly_Coolers

My Feedback: (7)

I am also going to try the 18x10 as suggested, and see if it helps first before swaping engines.

karolh

Sometimes just a simple change of prop size either up or down, can make a big difference in the way an engine / model combo performs.

3dd

My Feedback: (6)

sounds tail heavy to me,did you recheck the cg after repairs were made?

I_Fly_Coolers

My Feedback: (7)

Yes, actually added 12 more ounces to the nose this past weekend, was better but still mushed around the pattern. I know the plane is overweight too- supposed to be closer to 17 lbs. Nothing I can do to lighten it up- the previous builder just built the structure too heavy. Just very frustrating because the plane flew so well before the crash.

karolh

Maybe a good choice as a replacement engine would be a G45 or G62 converted to elect ignition by Ralph Cunningham. His conversions are legendary and reduces engine weight by approx. 1lb. and best of all, he gives a lifetime guarantee on his work.

Karol

Flypaper 2

Quadra 52 would fly it fine. Heavier than the 42 but you need the weight anyway.

I_Fly_Coolers

My Feedback: (7)

Well I picked up a Top Flite 18x10 today. I'm going to give it one more shot tomorrow before swapping engines, perfect weather conditions tomorrow!!! ...And a Toys-for-Tots fly-in as well !!