I bought one of those CMP knock off ARFs on eBay. For what I paid, it's not a bad bird at all. As you might expect, the instructions were at best sketchy and didn't include where the CG was. At first, I thought I'd use the CMP Hellcat's CG since they both have about the same wingspan. However, I believe the CMP version is almost 6" longer.

Has anyone flown (successfully) one of these Hellcats and if so where did you find the best CG to be? I've also found several sites on line that will help you calculate the CG of a bird but I've never used these before and I'm trying to reduce the probability of a "Hair raising" maiden flight.

Thanks in advance for your assistance.

[quote]ORIGINAL: Plano78

I bought one of those CMP knock off ARFs on eBay. For what I paid, it's not a bad bird at all. As you might expect, the instructions were at best sketchy and didn't include where the CG was. At first, I thought I'd use the CMP Hellcat's CG since they both have about the same wingspan. However, I believe the CMP version is almost 6" longer.

Has anyone flown (successfully) one of these Hellcats and if so where did you find the best CG to be? I've also found several sites on line that will help you calculate the CG of a bird but I've never used these before and I'm trying to reduce the probability of a "Hair raising" maiden flight.

Thanks in advance for your assistance.
[/quote



If you look up CMP vs Giantscaleplanes CMP puts their length at 53.5" which is probably what yours is and if so you can go with CMP's CG. It's Giantscale that list theirs at 66.5". I doubt yours is shorter then the 53.5" if it is 6" shorther as you say that put's yours at 47.5" way too short coupled. Think you just looked at Giantscale...

Go to the CMP build thread and someone will have it.
Good luck

Bull, I believe you are exactly correct on that, many thanks.

Hay,
I have been looking at CMP Hellcat and I understand it is very well built plane.
Also CMP planes are sold on two web sites that I know of, nitroplanes. com and raidentech.com
There is a very good explanation of how to find the CG of a plane in Dave Patricks book Aerobatics for Everyone.
The CG is based on a percentage (about 30% depending on the type of plane) of the cord length measured at the root and at the wing tip. I'm not going to get into details but leave it to the expert. Check out the book.
Good Luck,
[8D]

One easy way is to use this calculator. All you need are a couple of very easy to do measurements.

http://www.geistware.com/rcmodeling/cg_super_calc.htm

as a good resource, you may want to pop on over to the warbirds forum and check the 30+ page post on the CMP hellcat. There are lots of good tips on that thread, and alot of the people posting there also have the ebay knockoff plane, including myself.

Hello Hell-Cat owners, I just recently finished my CMP Hell-cat 90. The CG calls for 120-135mm, does anyone know if this is correct and has anyone flown thier bird yet? I am planning on the first flight Monday A.M. Can anyone give me any info on the flight characteristics.

I set my original CG at the limits given and found it to be tail heavy. Added some more weight to the nose and it flew marginally. Maiden when there is little or no wind. If a gust of wind gets under the wing, it will tend to roll over, so be vigilant on the sticks. You'll have to fly the plane instead of cruising around with a relaxing flight. Land with plenty of speed and fly it to the ground. Do not try to land by stalling it just before the wheels touch. The plane will float over the runway and will not lose altitude as the airspeed falls off, and it will tip stall before you are ready. I'd like to hear how it goes and if you found a similar experience.

Thanks JMatt for the info. I had that feeling it may-be a little touchy; just from past exsperience with CMP warbirds. I ("had") a Zero 50 size that was tail heavy even after balancing the plane it was hard to fly. I have the CMP Spitfire 90, with a OS .91 Max. This plane fly's great, no big suprises also is exstremly fast and aerobatic. The Hellcat 90 seem's a little short in length with such a large wing area. I didn't get a chance to fly today so hopefully this weekend I'll give it a shot...Cross my fingers! I put alot of work into the plane so I'd be bummed to crash first time out. By the way nice name; that's my name also. Well I'll post the first flight Saturday, Maybe add some pics if she hits the ground or has a good flight under her wings. Thanks again, Matt (starcop).

I posted these pics on another thread along with specifics.

http://www.rcuniverse.com/forum/m_25...tm.htm#4318693

The very long CMP hellcat thread started by Luke with various coments from Hal Humphrey is not a CMP its the copy . I spoke with hal and he purchased it off ebay like me , and I also know tha Luke says the same things somewhere in that thread .
Hal and I purchased ours for under $100 and I think Luke said $139 , both of those prices indicate that we have the copies plus they did show box art work and they were CMP copies .

Hello

I have one of the cmp Hellcats. Got it on EBay for 100.00. Completed weight was 15.3 lbs with G-26 and C.J. retracts (I don't think the retracts were worth the money). It is a floater, as far as warbirds go. Second flight could not get the gear down. So lowered flaps (43 degrees), about 15-20 percent power with a long flat approach and landed. I was very surprised at how slow the plane would fly (in ground effect of course). I slide about 7-9 feet and stopped with no structural damage.
A friend had the "knock off" Hellcat at the field yesterday and I was able the inspect it. I was wondering what the differences were between the two kits. I my opinion the only difference, besides the decals, is the price. His airplane had all the same panel lines in the fuse, same canopy, flaps, washout in the elevator halves, same cowl, same thickness of the fiberglass parts, same hardware. I did forget to look and the retracts, so I won't comment on them.
In my opinion this is a so-so flying airplane. Not bad, not good, just fair. But I looks very impressive in the air. Almost forgot, I set my C.G. at 127 mm.

Ryon L.

what engine and gear/ retracts did you use for the CMP Hellcat?? Ed Sarkisian-thx!!

1)15.3 pounds is major weight for this plane , are sure that is correct , I am not bashing you just worried ?
2)As stated before the CMP bash is not a CMP its a Flymodle , in China they copy each other and many planes come from flymodel.com factory .
3)CG , did anyone see the post (cant seem to find it now ) that is CG for dummies like me .
YOU take a string (rope) and tie it to the extreme end of the prop shaft , you take another and tie it to the rudder in a structurally stable area but as far back as possible , you hang the plane attach both ropes to a nail in the ceilt or rafter very securly . Level it , then you hang a weight off the same nail and let it reach the plane between both lines , it should hang on the plum line and show you where the CG is actually located , has anyone tried this ?

Your CG method will give the geometric center between the two suspension points. It has nothing to do with the aerodynamic balance point. Think of a plane that balances at the center point. I can't think of any, but then, my experience is limited.

damm I knew it was tooo good to be true ....[&o]was hopeing for that easy solution