RE: CMPro Extra 330L 50 size
 

Hi and thanks for the tips.

I already tried doing this. It ain't budging, it will turn but with great difficulty.

I'll have another go when the youngest sprog is in bed and if not do the CA thing

Cheers

RE: CMPro Extra 330L 50 size
 

I am posting this in case it will help somebody....

I, too, have had trouble getting this plane to fly well. Even flown by our Club's top flier it had a tendency to snap roll when pulling up elevator and to porpoise as it climbed through the first quarter of a loop (as if the pilot was applying the elevator in short jerks).

The elevator linkage was firmed up by inserting a support just before the fork in the pushrod, to eliminate sideways movement of the pushrod under load, and also by removing the elevator halves (not an easy job!!) and installing a thick U-shaped connector wire between the two halves so that they move together. But still the porpoising persisted.

Last week I replaced the ASP .70 4-stroke (already bigger than the recommended engine size) with an ASP .91 4-stroke that is of almost identical weight. That has resulted in an AMAZING IMPROVEMENT the plane now flies as expected, which kind of indicates that we were suffering from being underpowered and presumably the plane had been exhibiting stalling characteristics on the .70?

I am looking forward to exploring the flight envelope further, and hopefully moving the CofG back into or nearer the recommended range. It currently is about 10mm forward, as suggested in these forums.

Regards,
Bill

RE: CMPro Extra 330L 50 size
 

Hi Bill

many thanks for your comments on this, it really helps and its funny, last night I 'dry' fitted the elevator linkage and thought 'this thing definitely needs support close to where the wires separate'. I was thinking of just glueing in a balsa support with a cut out to hold the carbon rod in place. The elevator halfs are way too sloppy for my liking. Any left or right movement and they flap in oposite directions - not good.

When you say "removing the elevator halves (not an easy job!!)" do you mean fixing the two elevators together?

One of our guys has advised me to run my FA80 with 20% YS fuel to really get performance out of it, which I hope will help with the response and flight characteristics of this plane.

With his help, I hope next weekend, we are going to set the plane up and see what we can get out of her. I will document it all here.

Right home for lunch and I'll take some more pictures to show what Im doing.

Thanks again Bill appreciate the advice!


Guy

RE: CMPro Extra 330L 50 size
 

Heres a picture of the elevator carbon rod. What I propose to do is add a light ply support in with a hole for the rod to run through.

http://i48.photobucket.com/albums/f2...L/DSC00334.jpg

Tail is all done.

http://i48.photobucket.com/albums/f2...L/DSC00338.jpg

Ive not had any major build problems as yet although, as has been said before, the wing bolts don't fill me with confidence. Still got to measure my cars to see if it will fit in them with the wings permanently fixed even though I have a van too it may not be around forever.

Should get a lot more done tonight

cheers all

RE: CMPro Extra 330L 50 size
 

Hi Guy,
1. Pushrod support: I drilled out one of those large, red, double-ended, servo arms after glueing it to a suitable piece of ply - about 15-20mm wide and length to reach each side to the former. I then slid the arm onto the pushrod, reinstalled the pushrod, put epoxy onto the rear of each end of the ply strip, then slid it down the pushrod into contact with the rear former. From memory - it was a few months ago - I was able to reach in with a couple of small spring clamps to hold the cross-piece in place until the glue set.

2. Elevator halves: As mine were already glued in place (of course, because the plane had already flown! And they could still be flexed in opposite directions even with the pushrod support) I used a hacksaw blade to cut through the supplied hinges, then CAREFULLY drilled them out of both the elevators and the horizontal stab (very slowly and carefully!!), so as to be able to insert replacement Robart hinges. Actually, for the two innermost I drilled them out only a suitable diameter and depth to carry the wire joiner (see below). I drilled two new holes for innermost hinges a bit further out, and had to cut those two hinges a bit shorter because I seemed to strike the rod supporting the stab halves.
I bent a length of 3mm (1/8") steel wire into a U-shape to serve as an elevator joiner, and drilled a hole through each side of the vertical stab to line up with where the wire joiner would be located. I was able to retrofit the joiner this way because the stab is hollow and I could feed the wire in on an angle and twist it around to come out the opposite side (harder to describe than do!). The wire joiner has to be bent to the exact length to fit into the drilled holes.
Keep dry fitting the elevators and joiner to ensure everything lines up accurately, remembering to have no twist effect in the alignment of the elevators! When satisfied, I glued one side at a time with masking tape to keep the elevator pulled in to the stab.

I also had to install new horns because of having destroyed the very neat combined horn+hinge supplied by CMPro. I mounted these just inside where the joiner sits.

3. Wing bolts: I had the same concern, but concluded that the wing joiner is the primary support (I reinforced mine with a full length of dowel sanded to a tight fit). The bolts just hold the wings firmly against the fuse? (I hope!!)

If you would like some photos I could try to get them.

Regards,
Bill

RE: CMPro Extra 330L 50 size
 

Hi, i have just come across your forum,i have this plane sitting in my loft waiting to be built however all i seem to stumble across is negative reviews,surely a plane that looks as good as this can't be that bad.I just don't want to spend the time and enthusiasm making this model if it is indeed a complete dog.What is your honest opinion with this plane is it really a handful as many have suggested,i'm after some encourging info to give me the push to pull it out of the loft and build the thing.Thanks in advance for your time,Martin

RE: CMPro Extra 330L 50 size
 

Bill

Ive decided not to dismantle the elevator halves as you describe. It would be far better to do it your way I admit but from what Ive seen on mine the support stops the elevators from moving out of alignment and from what you say the porpoising still persisted until you upgraded to a .91

I'd still very much like to the pictures of what you have done for future reference. I think it will be useful for others in the future. I wish you'd seen the thread before I'd started on the stabs :eek: :D

I tried installing balsa supports loose just to try it and the movement of the elevator improved greatly, I am also going to add a support on the next former up too to help with the flex in the carbon rod. Its hard to tell how strong the support needs to be as there is no load on it, it just stops any movement side to side. I dont actually think it needs to be that strong. If you have pictures of your mods I'd very much like to see them.

Martin,

Im not in a position quite yet to comment on the flight characteristics but searching the forums here I have come to this conclusion:-

Instructions are inadequate and vague. COG is about 10mm forward from where the instructions set it - I think!

Build quality is pretty good. Ive not built many arfs myself. Always built kits or scratch built. Please take Bills advice and add a wire joiner for the elevators. Buy bigger wheels if you are going to be flying from a grass strip. Ive gone for 1/4" larger diameter. We'll see.

From the advice I have received from here and locally, I'd say positive vs negative comments on this plane are about 50/50 and usually people have quickly dismissed it without investigating why it wasnt flying right. Giving comments like 'this plane is rubbish dont buy!" are not useful without backing up your comments with details. Im not talking about my thread by the way just ones Ive searched. I think we have established it is not an ARF you can throw together and fly.

I should be flying mine next weekend if its finished and I can report back then.

cheers all

Guy

RE: CMPro Extra 330L 50 size
 

Thanks for the reply and comments,i look forward to reading your flight review,it is such a good looking model its difficult to believe that it is so bad,good luck with the maiden,Martin

RE: CMPro Extra 330L 50 size
 

Been spending a lot of time on her tonight/this morning (its 2am here) trying to get her ready for Saturday.

FA80s in now but I have a problem with the silencer, it won't fit under the cowl. So I either have to shorten it somehow or cut another hole in the cowl to accomodate the silencer

If I cut a hole it wouldnt protude much but I want to avoid it if I can. Any ideas?

http://i48.photobucket.com/albums/f2...L/DSC00357.jpg

http://i48.photobucket.com/albums/f2...L/DSC00362.jpg

Still got to mod my elevator rod too[:o]

RE: CMPro Extra 330L 50 size
 

Flew the extra on saturday. Lets just say I wasnt delighted with the performance. Its too heavy for this size plane.

With my FA80 for power and really on song I must add, it struggled with verticle. However it did fly okay and was stable enough. No signs of being tip stally. The problem came when my friend landed it and cut the engine on finals, not a good idea in hind sight but got some great pictures of the result! Without warning it quit flying more or less as soon as he cut the engine. Cracked the undercarriage slightly and a spat. The spats are too flimsy for my liking.

The plane was floating so well on low throttle but as soon as the engine was cut it nose dived. Not good. Bearing in mind the guy is an amazing pilot.

Snap rolls and knife Edge was good.

Im either going to fly it like I stole it or sell it, probably the latter and replace with a 58" Extreme Flight Extra which will do what I want.

Im not putting this plane down completely, I may even loose some weight at the front and try to flying nearer the recommended COG just to try it again.

http://farm4.static.flickr.com/3294/...825fccdaeb.jpg

http://farm3.static.flickr.com/2144/...95ff14bb03.jpg

http://farm4.static.flickr.com/3289/...dee2d9b5cc.jpg

http://farm4.static.flickr.com/3216/...e6af8f1eab.jpg

http://farm4.static.flickr.com/3009/...51c6a1438d.jpg

Does a nice upside down prop hang real good :D

RE: CMPro Extra 330L 50 size
 

Yup, bring the C.G. back, you may even want to go a bit further back than what you are contemplating.

The manual has it too far forward IMHO.

Once you get it dialed in, it should NOT drop the nose immediately on power off, until it hits stall.

However note that if you bring it back too far it may become more prone to tip stalling... though I've not found this to be a big problem.

"From the advice I have received from here and locally, I'd say positive vs negative comments on this plane are about 50/50 and usually people have quickly dismissed it without investigating why it wasnt flying right. Giving comments like 'this plane is rubbish dont buy!" are not useful without backing up your comments with details. "

You sure have that right!

I've been very happy with their planes, considering the prices, but I'm always looking for problem spots and correcting them.
This is something that many beginners do not realize that they need to do with ARFs.

RE: CMPro Extra 330L 50 size
 

Hi opjose

See Im getting conflicting advice from people in the know (more experienced than I). Ive had guys say they've done the math on the airfoil etc and the COG should be much more forward than it is stated in the manual. I must admit we set it up on the nose heavy side on the day, with the Saito FA80 this wasnt hard to do. The maiden was uneventful apart from that landing, accept for the fact there was no vertical! and I just cant see where thats going to come from.

"I put a 2C .46 Tower Hobbies engine into one and it flies pretty well. No problems with verticals." eh? I just dont get it!

I need to weigh it really to get a good idea but Ive done nothing out of the ordinary. All 591 JR servos, JR R700 Rx, Standard size batt. I made the carbon rod support out of balsa so I didnt add any extra unneccessary weight

I will give it another try and move the COG back to their stated one on the manual but further back? Woah not sure.

RE: CMPro Extra 330L 50 size
 

Hi guys just test flew my extra 330l 50 size today what a great a/c I have got a os 52 4 stroke in it swinging a 12x6 graupner prop I have set the cog at 80mm from the leading edge and it seems to be right I also dialed in flaps so I have a slower approach speed hope this helps anyone else who has bought this a/c I am nearly 60 so it can't be all that bad

RE: CMPro Extra 330L 50 size
 

Hi Airservices

Firstly gotta say I love your neck of the woods. I have family in Mandurah and Perth. What a small world.

52 4 stroke! Whats the vertical like on it? Surely must be lacking in power. Have you weighed it all up?

Ive still not managed to get another flight in since my maiden. I hope for Saturday maybe.

RE: CMPro Extra 330L 50 size
 

Some of the conflicting advice also arises because of the different versions that are available.

When in doubt double check the recommended C.G. and if it looks OK go with a C.G. just a tad forward to be doubly safe.


The T.H. engines are real stump pullers.

The .46 produces about 1.8 bHP and from what I've seen the specs are on the money with this engine.

If properly propped, it should pull the .50 around with authority, especially since this is a relatively LIGHT engine.

It sounds like your FA80 is not producing the equivalent amount of power.

Airservices says his is using a .52 4C engine.


That it dropped so quickly when the engine was cut, seems to point to the airspeed being too low to begin with, be it from too low of a pitch prop, or too retarded of an throttle/idle setting.

As it hits stall it will drop the nose somewhat hard.

RE: CMPro Extra 330L 50 size
 

just put the extra on the scales and it is 2.6 kg vertical it is a bit slow but ok for me flying at 1/2 throttle it is still quite fast rolls on low rates are nice at full rates it is very quick loops I have to build up speed but still ok no dropping off at the top all in all a very stable little a/c might move the cog back a little when I get a few more flights on it at the moment with the cog where it is full deflection on the elevators has no tendency to snap

RE: CMPro Extra 330L 50 size
 

Question - whats the CofG that everyone would recommend? As i was given this plane from a friend and i have no instruction manual.

RE: CMPro Extra 330L 50 size
 

G'day everyone,
I was wondering if you could tell me if i am on the right track with the CofG for this plane. I am running a OS .55 giving a Total Weight (without fuel or lead) of 2800 grams with the CofG at 110mm from the LE.

With half a tank of fuel and 500 grams of lead (just behind the fire wall) the CofG is 85mm from the LE.
This would make the AUW between 3200 grams and 3400 grams with fuel.
Is this sounding correct? or am i way off?

The previous owner only used 200 grams of lead to get this plane to fly great, so am i looking at the wrong CofG?
Thanks for your help,
PEZ

RE: CMPro Extra 330L 50 size
 

I just did these do they look right? The Cals are in cm's

RE: CMPro Extra 330L 50 size
 

Hi
im thinking of buying the CMPro Extra 330L 50 size, CMPro recommends a 46 2 stroke but from what ive read you are opting for 80's etc. Is there any problem with the O.S 46 ax??


Thanks Blake

RE: CMPro Extra 330L 50 size
 

CM Pro.

RE: CMPro Extra 330L 50 size
 

Someone has seen far too many movies... sigh...
[:@]

RE: CMPro Extra 330L 50 size
 

25% of the mean chord of the wing, measured at the root tends to be very safe.

You can adjust backward later after you've flown it for a bit.

RE: CMPro Extra 330L 50 size
 

Thanks for the reply opjose,

i gather that means its ok to use (ive only just turned 14 dont realy understand). Another thing if i were to use the 46ax would putting the battery pack in the cowl give me enough weight to get the desired CG (where is the CG from what it sounds like the manual is wrong) or should i upgrade and get a lager battery pack.

RE: CMPro Extra 330L 50 size
 

Hi,

I've recently built the exact same model but im struggling with the CoG, you say 80mm back from the leading edge is that from the wing tip or base????

Blake