Groovy 50 3A - Second time around

[viva_peru]

Hello,

When the Groovy first came a few years ago it caught my attention as I was starting to get interested in flying pattern. At the time, it was the ony plane that I knew off which had a large hatch which would make accessing the battery easy. In the end, I bought a kit and converted it using an AXI 4120/18 and a 5S1P 3200 Thunderpower pack. Since the plane was an ARF, there really wasn't much that I could do to make it lighter, so the conversion ended up being heavy: it almost weighed 6 lbs. I flew it a few time and it seemed to fly well, but for some reason I just never got comfortable so in the end I mothballed the plane so that I could use the equipment on a different plane (a Balsa Nova 40).

Well, as it turns out, World Models came out with a follow up plane, the Spot On, which seems to be a very good flier and this re-kindled my interest on the Groovy; maybe I had made a hasty decision. Since the equipment was already being used on a different plane, I ended up stealing equipment from yet another plane to bring the Groovy back on line. I also made a few minor changes and the plane is now a little lighter was well. It has not been flown yet, but I do not expect any problems (don't we all). Here are the specs:

First attempt:

Motor : AXI 4120/18
Controller: Jeti/opto 70 amp
Battery : 5S1P 3200 mah Thunder Power Extreme
Prop : APC-E 14x10 and 14x12
Power : Close to 800 watts at about 50 amps.
Weight : 96 oz

Second attempt:

Motor : Mega 22/20/3 geared 4:1 through a MEC box
Battery : 5S1P 3200 NEU engergy (got them on sale, they work great!)
Controller: Jeti/opto 40 amp (might need a bigger one)
Prop : APC-E 14x10 or 14x12 (need to test)
Power : 630 watts at 36 amps to 750 watts at about 42 amps
Weight : 90 oz.

For the second attempt, I replaced the landing gear with a carbon fiber, single piece, unit from the 3D Hobby Shop. Incredibly light and it save me a few ounces. The rest of the savings came from using a lighter motor and being able to place the nose weight as far forward by using a heavy aluminum spinner. I also sealed the control surfaces for the second attempt.

I have enclosed a few photos. I will provide an update once the plane has been flown.

Teo

[viva_peru]

Hello,

I got a chance to fly the groovy for a second time this past Sunday. The plane flew reasonable straight once a gave it a couple of clicks of up elevator trim. With the 14x10 prop the plane flies reasonably fast but does not seem to "get on step" so I might try a 14x12 and see what happens. At any rate, the plane felt heavy in spite of the fact that the CG had been moved back 15 mm to the proper 135 mm that the manual calls for (I guess that I was little too cautious the first time I flew the plane a few years back).

I only flew once that day because I wanted to take the plane home and check the motor thrust angles (maybe too much down thrust) and the incedence of the wing and stab. As it turns out, the stab has 1 degree of positive incidence relative to the wing; no wonder it needed up trim. I am in the process of correcting that so that I can give it a try once again. There is no reason why the plane should not fly well, so I am going to give it a little time to see if I can get trimmed properly.

I have enclosed a photo of the plane at the field next to my current favorite plane, a Balsa Nova 40.

Teo

[viva_peru]

Hello again,

I got another chance to fly the airplane this weekend. Since the wing is a two piece design joined by an aluminum tube, changing its incidence was relatively simple. I enlarged the holes that the anti rotation pins fit into, and then used paper soaked with CA to increase the size of the pins. After some careful triming with an X-acto knife and sand paper I was able to set the wings at 0 degrees relative to the stab. I also changed the prop from a 14x10 to a 14x12 to give the plane a little more power and speed. The currents now run in the low 40 amp range and the plane has about 750 watts to fly on.

Well, the flight that followed was better but it still needs some work. Some up elevator trim was needed but not as much as the first time around. I am going to increase the incidence of the wing to +0.5 degrees and leave it there. The plane feels somewhat nose heavy, so that will be the next step.

I did some basic manuevers such as loops, rolls and some inverted flying and the plane feels different than the Balsa Nova; it seems to track better. Also, with the 14x12 prop is now have the speed and power for long vertical lines. I would guess in the 250 to 300 ft range, more than enough for a nice stall turn.

I am not quite there yet, but I think that the plane does have potential.

Teo

[kmp647]

I miss mine, its a great flyer on that setup.
I used the 4120/18 15x10e 5s 3700s

mine had incidence issues too.

Kevin

[viva_peru]

Kevin,

Gald to hear that you liked your Groovy and that mine is not too far off with mark regarding the need to adjust the wings. As it turns out, I also found out that the stab had a little bit of a warp to it. The plane had been sitting in the basement for awhile, so maybe the humidity was responsible for that. Fortunately, a little heat from the covering iron took care of it.

If it ever stop raining in Michigan, I might a change to try it once again this weeked.

Teo

[viva_peru]

Hello,

The weather finally cooperated and I was able to get a few more flights in. This summer has been somewhat windy for Michigan so I have not been able to get in more than a few flights on the Groovy. Since I am still triming it, I prefer to fly on calm days.

In general, the airplane is starting to grow on me. My intent is to use it to fly the Sportsman routine and from what I can see, it can do it quite well. The plane tracks well and I like the way it rolls; it feels more precise than the Balsa Nova.

So far, I have moved the CG about 5 mm rearward of the recommended spot and the plane feels pretty stable. I have been playing with the incidence on the wing and stab and I have come to realize that the robart incidence meter I have is not very accurate. I ended buying the Hangar 9 digital meter and it seems to be better, but not accurate to the 0.1 of a degree as they claim. I am guessing that it is accurate to within 0.25 degrees, which is probably good enough. Using the new meter I have come to realize that the stab is warped by about 2.5 degrees from one end to the to other. In essence, one tip is neutral while the other will have 2.5 of positive incidence. This probably explains why I needed airleron trim in spite of the wings being even. On top of that, the plane need up-trim to fly straight.

Since the stab is a sheeted airfoil, taking the warp out was a challenge. In the end, I removed the covering from the bottom surface so that I could soak it with water and use a heat gun to dry it while twisting it in the proper direction. The method worked reasonably well and now the warp is of only 0.5 degree from one end to the other. I allowed it to sit for a day or two and it seems to be holding, so I recovered the stab. Although not perfect, it should be much better. We will see how it flies.


All in all, I think that it is a pretty decent airplane, especially for the price at the time ($ 139.00). If I were in the market for another plane in this size range I would consider the Spot On 50 which was the follow on to this plane.

Teo

[viva_peru]

Hello again,

Another brief update. As it turn out my NEU energy batteries were getting a little tired so I ended up buying a pair of 3700 mah Rhino's (5S) as replacements. So far, I have been impressed with the batteries, I had to prop down in order to keep the current below 50 amps. Right now the plane is flying on a 14x10 prop at about 45 amps. I believe that the plane now has about 850 watts of power available to it.

Since the new batteries are 3oz heavier than the old ones, I removed almost 4 oz off the nose and still managed to balance the plane pretty close to where it did before. The AUW remained the same at 90 oz (scale is +/- 1 oz).

While flying the plane this weekend, one of the more experienced pilots took a look at it and said that it flew quite well. He did not get a chance to fly it as I was out of batteries, but mentioned that it might still be a little nose heavy based on my description. So, when I got home, I removed the flight pack, added a Castle BEC and put the heavy aluminum spinner back on. The plane lost a couple of oz and the CG shift was of about 5 mm, so I think that I am safe. Hopefully, I will get to try it out again this comming weekend. I have never fiddled so much with a plane in order to get it to fly well; so hopefully, the effort pays off.

Teo

[Ed Lyerly]

Teo,
Hang in there .... I think you are getting very close to being a "happy camper" :).
I have found that pattern birds like this (with their long tails) will tolerate moving the CG back quite a bit .... and do not have the tendency to drop a wingtip or snap like an aircraft with a shorter tail moment (like a warbird). Some of mine will slow down to a rediculous landing speed without dropping a wingtip.
Ed

[jrb]

The Groovies (50 & 90) are Gr... Cool!

I'm a happy G driver too -- 90.

[viva_peru]

Thanks guys,

As it turns out, I started with about 4oz of lead in the nose which is now all gone. In the mean time I did not notice a significant change on how the airplane handled aside from needing a little less down elevator when inverted.

Hopefully, removing the receiver pack won't tip the balance against me, but in the end, I will have removed about 5 oz of nose weight. With all of that weight missing, I replaced the lighter aluminum/pastic spinner with a heavy aluminum one which helped keep the CG pretty close to where it was. I can still shift the CG a little further back by simply reverting to the lighter spinner. That would be nice as it would bring down the plane's weight a little further.

Hopefully, I will get to try it out this weekend.

Thanks,

Teo

[flyyyer]

All in all, I think that it is a pretty decent airplane, especially for the price at the time ($ 139.00). If I were in the market for another plane in this size range I would consider the Spot On 50 which was the follow on to this plane.

Teo
I think I would stay with the Groovy as the Spot On does not have the battery hatch the Groovy has. The Spot On is designed as a pure IC model whereas the Groovy has been designed with electric power in mind. Our Groovy has been converted to a wire gear - much less troublesome in those less than perfect landings - and has proved a great follow-up to the Multiplex AcroMaster foamy.
Lorenz

[viva_peru]

Lorenz,

You are right about the Spot-On not having a simple hatch for battery access; however, if I were to convert that model, I would probably make the canopy removable in order to gain battery access. Or, out of desperation, I could use a Saito .72 that I have sitting around :eek: . Heresy I know.

This plane has proven to be a good learning tool as it is teaching me how important it is trim the airplane properly in order to get it to fly correctly. Having said that, when trying to fly the Sportsman schedule at the proper distance I find that the model is hard to see well: It is particularly difficult to see if the wings are level. In that sense, a bigger plane would probably be a better option.

If I remember correctly, believe that "your" Groovy was actually your girlfriend's which I thought was great. I took my girlfriend up for a flight on my LT-25 earlier this summer and she found it to be more difficult that it appeared, so she didn't try it again. But at least, she did. Later on I had a chance to teach some else how to fly using their trainer and came to realize that my LT-25 is set-up to be too twitchy to be a good trainer. Maybe I should have her try it again...

Teo

[flyyyer]

If I remember correctly, believe that "your" Groovy was actually your girlfriend's which I thought was great.
Teo
Indeed it is! Actually when we moved 12 years ago and dug out my old models from the attic she was the one saying "I've always wanted to do that - show me!" And that's where we both started again. And going strong ever since, all electric by now. That would be her getting ready to fly a World Models Ultimate. Sorry for hijacking...
Lorenz

[viva_peru]

Lorenz,

Don't worry about hijacking the thread at all. I just thought that it was neat that both of you enjoy flying model airplanes. As you probably know, it is not very common to have couples who fly together. Thank for posting the photo. Don't worry, I will not ask who might be the better pilot ;) .

Neat story.

Teo

[viva_peru]

Well, I got a chance to make another 5 flights yesterday and the only thing I can say is what a difference! After removing the receiver pack and adding a BEC the CG ended up shifting 15 mm rearward and not 5 mm as I had originally thought. I was a little concerned about flying the plane after such a significant CG shift, so I added1 oz of nose weight just to be safe.

The CG feels just about right now. The need for up and down elevator whether I am right side up or up side down has almost disappeared and the plane feels much lighter in the air. It does not feel twitchy, so might still be able to remove the 1 oz I added for safety.

After everything was said and done, the plane has lost about 1/2 lb from when I first flew it. It and it actually feels light when I pick it up, even with the flight pack in place. The AUW is now at 88 oz.

I am glad that I stuck through the process as the plane has turned out to be quite nice. I still need to make some minor adjustmenst to the thrust line, but for the most part, the plane is there.

Ed and JRB, thanks for the encouragement.

Teo

[jrb]

Good for your Teo!

[viva_peru]

Hello,

The past few weekends have been pretty nice by Michigan standards in November, so I have gone out flying every opportunity I've had.

So far, I have logged another 12 flights on the Groovy since the re-balance and it seems to be flying very nicely. There is still some more work to do trimming the plane, but I think that it is pretty close.

As it turns out, one of our club members had his Black Magic out yesterday so I was able to take a couple of pictures of the two planes next to each other. The only thing I can say is that the Groovy looks sooo small next to it. No wonder it is hard to see when practicing the sequence.

Mike built the Black Magic from a short kit and has done a great job, the plane just looks great. I would love to have one as well, but can only think of how expensive it would be as an electric. Mike was hoping to maiden the plane yesterday, but I had to run to work so I did not get a chance to see it fly. Bummer. I have enclosed a couple of photos of the planes together.

Teo