RE: CMPro P-51 (50 size) test flight crash

RE: CMPro P-51 (50 size) test flight crash
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RE: CMPro P-51 (50 size) test flight crash - 5/4/2008 8:45:37 PM

emoore1978

Posts: 5
Joined: 5/2/2008
From: killbuck, OH, USA
Status: offline

ok.....i moved the cg 3/4 of an inch forward of the book.....balanced it upside down on my marks....i had originally added (5)....1/4 oz weights to the tail because it very very nose heavy.....and it wasnt quite enough to level it....but i let it go at that point. after moving the cg forward.....its still just a tad nose heavy....NO FUEL to the tank. so....i assume im being safe at this condition at the least....correct? and why do they balance these upside down?.......is it to get the weight of the fuse to hang on the wing?????

(in reply to Larry S)

Post #: 26

RE: CMPro P-51 (50 size) test flight crash - 5/5/2008 1:20:05 AM

Larry S

Posts: 443
Joined: 3/3/2004
From: Manteno, IL, USA
Status: offline

emoore,
A tad nose heavy?? Perfect, just where you want to be. And to answer your question, yes. Upside down the plane will hang. Now the one thing you want to keep an eye on when landing is don't stall it, keep the speed up. IF you can get yours to fly as nice as mine, you'll be able to make nice slow flare outs, but first you need to play with the CG to get it correct. I've found the best way to do that is move your battery pack. Good luck with your plane.
Larry
PS: I'm really surprised your plane is that nose heavy but then again, I only have experience with the CMP 50 Corsair. I know with that plane it is very tail heavy to start out.

(in reply to emoore1978)

Post #: 27

RE: CMPro P-51 (50 size) test flight crash - 5/6/2008 2:39:02 PM

Sturtz

Posts: 1501
Joined: 9/22/2004
From: El Reno, OK, USA
Status: offline

After I repaired mine I took it out a week or two ago. After moving CG forward it flew pretty darn good. Had to walk it to the asfault runway because it noses over easily. I put larger wheels on it when building but it could use even larger ones. With the small wheels (no wing area left to inlarge gear bays) it's pretty much a paved tarmac plane. Landed fine,,,but again had to keep it on hard turf.
No doubt I was flying it last summer slightly tail heavy but not enough to cause major concern. Turned out to be a faulty aileron servo extension. Moved the battery forward and strapped to fuel tank. Much better !!!

Like Larry, I used the GP CG Machine. Before placing it on the balancer I found the main spar,,, came forward of it slightly.(maybe 1/4 "

and balanced there. Flys nicely now and will make a fairly sharp turn now without snapping. Hammerhead stalls are uneventful now too thank goodness. Again,,, they are CMP. They are heavy and they are small. Most of the larger birds CMP makes fly just fine after dialing them in and putting the right engine up front. They will either make you a better warbird pilot or cause you to switch to Cubs and trainers.

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< Message edited by Sturtz -- 5/6/2008 9:44:40 PM >

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(in reply to Larry S)

Post #: 28

RE: CMPro P-51 (50 size) test flight crash - 5/6/2008 7:50:19 PM

miklos

Posts: 187
Joined: 4/1/2004
From: Meriden, CT, USA
Status: offline

I had one and only one CMP plane. A 50 size P-40. What a disaster.

Beautiful looking plane, but on it's maiden, she went straight up like a rocket about 20 feet and then tip stalled and crashed.

Yup.... tail heavy. What a disapointment. Strange thing is a few months ago that plane was reviewed in one of the magazines and they gave it good marks and no mention of the CG being off. Go figure.

I won't buy another CMP after that fiasco.

< Message edited by miklos -- 5/6/2008 7:53:24 PM >

(in reply to Sturtz)

Post #: 29

RE: CMPro P-51 (50 size) test flight crash - 5/6/2008 8:54:39 PM

KentuckyColonel

Posts: 427
Joined: 4/20/2007
From: Mission Viejo, CA, USA
Status: offline

quote:

ORIGINAL: miklos

I had one and only one CMP plane. A 50 size P-40. What a disaster. Beautiful looking plane, but on it's maiden, she went straight up like a rocket about 20 feet and then tip stalled and crashed. Yup.... tail heavy. What a disapointment. Strange thing is a few months ago that plane was reviewed in one of the magazines and they gave it good marks and no mention of the CG being off. Go figure. I won't buy another CMP after that fiasco.

I loved the CMP P-40.....while sitting in the pit area. Flight number three......Loop, bank to turn right out of the loop, tip stall at 95-100 feet altitude, spin into the ground. Still can't find the Aces of Iron pilot......

(in reply to miklos)

Post #: 30

RE: CMPro P-51 (50 size) test flight crash - 5/6/2008 11:20:04 PM

emoore1978

Posts: 5
Joined: 5/2/2008
From: killbuck, OH, USA
Status: offline

thanks all for you info.......i still have doubts about the cg on this cmp p-51....and also on my cmp 182.the skylane will sit on the mains....but push down on the tail.....and it sits there. havent flown either of them yet.....i think im gonna add weight to the nose of both....make em nose heavy....then take it from there. its a safe way to try em out. and yes....i did use the cg point according the cmp plans on this skylane....i questioned them....no reply. they make a very nice plane....a very heavy plane....but the cg cant be right. my tank is even half full on the 182 with a 4 stroke as far forward as possible.

(in reply to KentuckyColonel)

Post #: 31

RE: CMPro P-51 (50 size) test flight crash - 5/7/2008 5:53:05 PM

Larry S

Posts: 443
Joined: 3/3/2004
From: Manteno, IL, USA
Status: offline

Instead of adding more weight, try to move whatever you can as far forward as possible. I have a Jemco P47 I maidened yesterday and I have the battery pack in the cowl under the engine mount. I made a small tray to set the battery pack on and secured the battery pack to it with velcro. I know we're talking two completely planes but they both have one common fact, they're both tail heavy planes. At least on the Jemco kit they give you the right location for the CG as on the CMP 50 Corsair, that CG location is way off but hey, look at where they have the machine guns located and you can see they didn't go far into depth on where things should be but I'll still stand by what I said before, once you get the bugs worked out of a CMP plane, especially the 50 Corsair, you'll have a real fun plane to fly. By the way, my P 47 is glassed, full cockpit with pilot, retracts and a vortact bomb drop, running on a Saito 100 and on it's maiden flight, flew perfect with only two clicks of down elevator needed. I still had to add two ounces of lead under the motor to balance it.
Larry

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(in reply to emoore1978)

Post #: 32

RE: CMPro P-51 (50 size) test flight crash - 5/7/2008 10:46:19 PM

emoore1978

Posts: 5
Joined: 5/2/2008
From: killbuck, OH, USA
Status: offline

your right on throwing out them directions.....if i were a newbie builder.....i could never even get the plane together with what they furnished. as i have experience....i realize that there is a cg location problem.....i dont own a balancing machine....i always done mine on my fingers. in 30 years....it hasnt failed me yet.....i choose to stay forward of the cg if in doubt.....and work my way back. cmp planes are heavy models....compared to balsa....but the scale is superb. i guess you have sacrifice something. myself....i wont ever buy another cmp airplane....if they cant get the cg right.....and clarify some of the building problems when you contact them....then im not interested. i was told by another hobby dealer that they dont communicate well.....they owned by china men. i will buld my own from now on. a lesson learned for me. end of my story on these cmp models.

(in reply to Larry S)

Post #: 33

RE: CMPro P-51 (50 size) test flight crash - 5/8/2008 12:24:53 PM

Larry S

Posts: 443
Joined: 3/3/2004
From: Manteno, IL, USA
Status: offline

I don't blame ya. Would be so easy for them to correct their mistakes and have a nice warbird. I guess what got me started with CMP was I wanted a Corsair without retracts already installed so that left out Hanger 9 for me. And like you my first CMP was balanced where stated on the "directions". On the maiden flight I had my hands full but got it back with no damage and that is when I started playing with the CG and I finally got it to fly nice until I put it in a snap roll and it wouldn't recover. On the second CMP Corsair I already knew where the CG should be and that it needed nose weight so I reinforced everything in the cowl and forward of the CG and went with a larger engine and that one flew great. I had the plane on a charger over night and went out to the field and got one flight in but on the second flight, the plane lost control and went in. Upon checking on what had happened I discovered the battery pack was completely drained and only after one flight. One battery had shorted out. I'll take blame, I now check my battery packs before each flight. I am waiting until the larger CMP Corsair gets back in stock and will try that one.
Larry
PS. Get one of those balancing machines. So much easier to balance a plane with one of those and much more accurate on keeping the CG where it should be. Well worth the money.

< Message edited by Larry S -- 5/8/2008 12:32:04 PM >

(in reply to emoore1978)

Post #: 34

RE: CMPro P-51 (50 size) test flight crash - 7/18/2008 1:35:00 AM

twinbrother

Posts: 125
Joined: 7/20/2004
From: Sherman Oaks, CA, USA
Status: offline

I just finished my 46 size P-51 Mustang from CMP and the CG of that plane is the same CG location of the 50 size one posted in this forum. Doesn't sound right. People are right to throw out the CG recommendations of these CMP planes. I had another 25 size Zero from Nitroplanes.com and the CG was 1" too far back on that, making it tail heavy. It crashed on maiden flight. I finally built the second 25 size Zero, moved the CG forward, and it flew awesome. I just can't understand why these guys at CMP can't get the directions for the CG correct. It's funny that everyone who ****es to Nitroplanes.com about how terrible the CG is on their planes that they say it's always the first time they hear about it. I've called them about the CG on every single plane I've ever purchased from them, a total of 4, and they say the same thing, "I'm the first person to grumble about it." I stopped buying from Nitroplanes.com because I didn't want to take my chances on terrible CG instructions anymore. Their products are cheap, but so are the instructions. And Raidentech.com, Bananahobby.com, Toyneer.com, Nitroplanes.com, are all the same company. Good priced products, okay quality, terrible instructions. You want a good flying warbird? Try the Phoenix Spitfire. Flies like it's on rails. And with retracts included, it's a great deal.

(in reply to Larry S)

Post #: 35

RE: CMPro P-51 (50 size) test flight crash - 7/18/2008 3:38:10 AM

wdrosa

Posts: 2
Joined: 12/8/2007
From: cantonment, FL, USA
Status: offline

The 3rd P-51 I got from them, I set the CG just in front of the spar (right about where the rivit line is). It flew great after that. Just dont let it slow down. I did and it tip stalled and I could not recover it in time. It was another total loss. I finally broke down and got the Topflite P-51 gold edition arf .60 size. This one flies fast and slow very reliably. Most important is that the CG is dead nutts on the money. I should have got this one first. Good luck with yours.

(in reply to twinbrother)

Post #: 36

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