NP Ultimate Bipe/Cautionary advice (Full Version)

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deckert -> NP Ultimate Bipe/Cautionary advice (2/14/2008 7:41:53 AM)

1. John, from NP, responded very quickly with respect to problems I've had with this bird.
2. John also offered to refund my cost, upon a return, to which I politely declined. (ever hopeful to maiden this cutie)
3. NP support never responded but John did.

Irrespective of that, I offer the following cautionary advice "for this plane only" and nothing against NP. After the build, I was unable to set my CG per mfg. instructions. I searched all venues and solicited advice from several individuals on setup from different sites. I added 3 oz. of lead to the nose and was still to tail heavy to obtain CG. I 'suspect' I would have to add another 1.5~2.5 oz to get CG. The AUW after the build was 28.7oz. Unfortunately, the bird felt like a brick after adding the extra 3oz. I did 3 taxi runs to get a 'feel' but gave up any desire to go airborn as I had no desire to crash, and possibly ruin, any electronics. CG after the added 3oz came in @ 63mm, still 13mm behind mfg. of 50mm. Given the reviews and build advice I've seen posted, I 'suspect' [8|] there's a marble hidden under the covering of this bird. Just kidding John...

This post is not a slam against NP, but it is a caution on this bird. I would recommend a return if you experience the above problems. For whatever reasons, I must have got the dreaded Monday built build after a drunken weekend. I only wished now, (belatedly) I had accepted Johns offer for a refund.

Dan



opjose -> RE: NP Ultimate Bipe/Cautionary advice (2/14/2008 4:45:04 PM)

The problem is not with the plane, but rather with the longer battery packs you tried.

The "standard" 1800-2200 sized battery puts the bulk of the mass too far backward to hit the recommended C.G. with ease.
It wasn't designed for that type of battery.

So the packs you used put the C.G. too far back of the recommended.

BTW: It DOES fly this way just fine as I've tried it.

However if you wish to get the C.G. right on the money, use smaller or thicker packs.

I've used 3S2P 2800mAh 11v 12C packs which not only fit perfectly but bring the C.G. forward more than the recommended.

Of note is that these were actually fairly inexpensive when I purchased them, because they use two 1400mAh packs in parallel in the same package.

I've used 1200 through 1800 packs that were a bit shorter than say 2100mAh packs, ( typically these are 15C or less in rating ) and these also bring the C.G. in line. NP sellls serveral that are perfect.

And of course you can also use a heavier motor.

There is nothing "wrong" with the plane per-se and there have been several reviews of it in it's various forms that like it a lot... a return is unwarranted IMHO as this is not a defect.

It's a great flyer when properly configured. See the other threads here about setting it up.

It is a good idea to alert anyone who purchases one that they need to be aware that to get the C.G. right, that they must choose the right components, that's all.... e.g. use the shorter battery packs.




nitrostaff1 -> RE: NP Ultimate Bipe/Cautionary advice (2/14/2008 11:57:48 PM)

Not a problem and I'll take care of you. Let me have your order number and I'll issue RMA.

Thanks
John
Nitro Planes
quote:

ORIGINAL: deckert

1. John, from NP, responded very quickly with respect to problems I've had with this bird.
2. John also offered to refund my cost, upon a return, to which I politely declined. (ever hopeful to maiden this cutie)
3. NP support never responded but John did.

Irrespective of that, I offer the following cautionary advice "for this plane only" and nothing against NP. After the build, I was unable to set my CG per mfg. instructions. I searched all venues and solicited advice from several individuals on setup from different sites. I added 3 oz. of lead to the nose and was still to tail heavy to obtain CG. I 'suspect' I would have to add another 1.5~2.5 oz to get CG. The AUW after the build was 28.7oz. Unfortunately, the bird felt like a brick after adding the extra 3oz. I did 3 taxi runs to get a 'feel' but gave up any desire to go airborn as I had no desire to crash, and possibly ruin, any electronics. CG after the added 3oz came in @ 63mm, still 13mm behind mfg. of 50mm. Given the reviews and build advice I've seen posted, I 'suspect' [8|] there's a marble hidden under the covering of this bird. Just kidding John...

This post is not a slam against NP, but it is a caution on this bird. I would recommend a return if you experience the above problems. For whatever reasons, I must have got the dreaded Monday built build after a drunken weekend. I only wished now, (belatedly) I had accepted Johns offer for a refund.

Dan





deckert -> RE: NP Ultimate Bipe/Cautionary advice (2/15/2008 9:08:06 PM)

John, I'm going to accept your offer for an RMA. The Order # was yhst-17210252890263-36264 as received from NitroPlanes.

opjose, and others, have been very useful with respect to advice/suggestions on this plane. In fairness to trying everything offered up to help, I tried the final thing I could think of to obtain CG. I offer this up as information only.

I installed dead weight into the battery tray area to obtain CG. Nothing was placed past the first former located behind the firewall nor was anything placed ahead of the firewall. All electronics were in place. The end result was 1lb.~1.1 oz of dead weight to obtain CG @ 50mm mfg specs. I can imagine some people think I'm nuts on this issue so I took some pics.

I tried uploading the images here but the server won't connect. So I uploaded them to http://www.rcgroups.com/forums/member.php?u=177795

Dan




opjose -> RE: NP Ultimate Bipe/Cautionary advice (2/20/2008 5:03:10 PM)

quote:

ORIGINAL: deckert

opjose, and others, have been very useful with respect to advice/suggestions on this plane. In fairness to trying everything offered up to help, I tried the final thing I could think of to obtain CG. I offer this up as information only.




WOW!!!!!!

Amazing.

Great pics too.

I can easily see that I have my C.G. point further back than you do, but I do fly my plane w/o problems.

If you look on the pic where you have the plane on the balance, immediately to the rear of the wooden beam you are using is a curved cutout in the carbane.

If I place my finger on the top most point, or to put it another way, right in the curve itself, at the rear, that's where I have my C.G. with an 1800mAh pack in place.

I fly the plane this way.

It MAY be better with it a bit forward.

I can't say that the plane is either over responsive or tail heavy this way though.

I also have a tail gear installed instead of a skid. My cowl looks like it sits further forward, but that may be an illusion as it appears yours is not screwed down in the pic.

I originally modeled the plane in G3 to verify that it would fly where I had the C.G. ( see the G3/G4 swap pages for the downloadable variant and color scheme ).

I'd advise to put the motor as far forward as possible to anyone owning this plane.

Hey Nitro, if you want to send me his plane, I'll take it!





deckert -> RE: NP Ultimate Bipe/Cautionary advice (2/20/2008 7:24:38 PM)

opjose, "WOW!!!!!!"

That was my thought as well. I just didn't know what else to do. I sent the bird back yesterday. I asked John if I should cut the tail feathers off & he said yes. I left the vertical fin on but cut the Horiz. stab off @ the fuse on both sides. Although it could be routered out and replaced w/a new horiz. stab. There was quite a bit of free area in the slot. I tried posting the pics here but the darn server kept dropping off so I posted them @ RCG.

There's no tw because the 2nd runup taxi lost it & bent the wire all to heck so I pulled it out & put the skid on. The cowl wasn't screwed down, just set in place over the holes to show the balance. The whole weight thing just had me running scared & I had no desire to go down as fast I could go up.

Dan



dirtybird -> RE: NP Ultimate Bipe/Cautionary advice (2/22/2008 12:53:57 AM)

I found this model impossible to control when set up as the manual says. Ailerons movement 15 cm each way is way too much. I wound up disconnecting the top wing ailerons and reducing the bottom wing movement to about 1/4 on lowrate and 1/2 in on high rate.



opjose -> RE: NP Ultimate Bipe/Cautionary advice (2/22/2008 1:37:50 AM)

I have mine set just a bit more than what the manual says, but I have a lot of expo on it.

Same for the tail.

Usually I max out throws, then dial down to less than the recommended for my low rates.




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