My Jitterbug flies superbly

[Colin Naylar]

Slightly strange thread title but I just wanted the world to know that I completed Alex Whittaker's Jitterbug and have been flying it for the past week or so. I am extremely happy with it. It sits solidly in the air and seems to do all that its told with no fuss or bother. Mine is probably a little underpowered at present but I am very happy as things are for the time being and I can always put a bigger prop on it when I get braver.

It has an Emax BL2826/06 motor turning a 11x5.5 prop. It is producing 500w of power according to my wattmeter and weighs in at just under 5lb. The motor will go up to 700W - too much for me I think!

Did anyone else build one?

 

[Colin Naylar]

I guess not then

[Tim Mackey]

HERE

 

Does foam count

Edited By Tim Mackey - Administrator on 21/07/2011 19:34:45

[Colin Naylar]

Not really Tim....

 

...and it does make you wonder about the monthly free plan, doesn't it ???

[Tim Mackey]

LOL, well I tried .

[Tom T]

LOL Its ok Tim . I can't say that i have built one but i'm sure that someone has in the forum. I'll post a random comment ever so often to keep near the top so that people can see. (if i'm allowed by the Mods)

 

Tom

[Tim Mackey]

Still, Tom says its OK, so that's a relief

[Andy48]

Hi Colin

 

I am just starting to build mine, I may be some time!

 

I too have chosen to build the electric version and also am going to use the Emax 2826. I am looking at a couple of changes, a fixed undercarriage instead of the wing bands, possibly using wing bolts instead of bands, and lowering the top of the rear fus as it looks a bit out of proportion.

 

I know about the wing dimension problem, are there any other problems you found when building it?

 

[Colin Naylar]

Hi Freeatlast ( from what? - the mind boggles)

 

The only other slight problem is that F2 is the wrong size.

 

You may want to have a look at another thread that I began when I found out about the wing problem - 'Jitterbug wing anomaly?'

 

I just started this thread after my maiden to try and generate a bit of interest. I did fix the u/c after a few flights but I'm not brave enough to dispense with the wing bands yet, I guess it depends on your experience/confidence. Good luck with the build.

[Myron Beaumont]

Colin

As you know from the other thread,I'm currently building a Jitterbug (with modifications).With the intended ASP 61 up front ,can you give me a rough idea where the Rx battery and servos will have to be for the correct C of G and did you put the elevator servo in the tail or midships .I have decided after all to use 2 standard servos in the wing. At the moment I have got as far as wondering whether to use bands on the U/C and wing or go down the normal route .Am erring on the side of the normal route as I see no advantage to using bands based on past experience .Have you had any unplanned arrivals where the bands have actually saved you from serious damage ?

By the way, any future buildes might like to know that if you use the dihedral braces as shown on the plan, then the actual dihedral will end up as 1 1/2 inches at one wing tip ,not 2 inches. Don't ask me how I know .There are other minor anomolies on the plan ,but nothing that doesn't become immediately obvious .eg The cabin perspex as shown would prevent the removal of the front hatch unless you undid the screws holding it due to the angle of the top surface on the nose .I have made a fully removable hatch with perspex attached held by a dowel at the rear (into D1 ) and a small screw at the front .Access to the tank which is one inch higher to conform to normal positioning and maybe the Rx battery underneath is a lot easier now . Did you notice as well on the plan that F2 and F3 are shown reversed from the side elevation to the plan from above Niggling little things I know ,but could be off putting to a beginner.-just like wing anomaly noticed by you all building .My wing is deep enough to hold standard servos without projecting into the airstream now by the way by increasing the wing section thickness slightly and the wings are completely covered in 1.16" balsa

[Colin Naylar]

Hi Myron

 

Re your C of G question, because mine is Electric power I don't think I can help - my LiPo goes where your tank is and I have also had to put extra weight (200g or so) up front as well. As for unplanned arrivals - well, as soon as I did away with the u/c bands and screwed it on, I did have a bit of a heavy landing which took out the ply u/c support quite cleanly. No other damage and it was fortunately easy to fix. No, I can't say that I have ever been especially thankful for wing bands, but never say never!

 

As I said before I can't see how Alex made the front hatch easily removable, but my Lipo battery hatch, in front of the cockpit is removable in the same manner as the plan. On mine it is cockpit that is fixed with a front wall.

 

I agree about the plan and all the little discrepancies - can't see how they all crept in but there don't seem that many people building it so I guess its not a big problem. I dealt with the wing anomaly by, as it were, cutting the fuselage through the C of G point and pulling the two parts apart by 1/2". Not literally of course but on a photocopy of the plan. Seemed to worl ok and the real C of G is in the same place.

 

It'll be interesting to see how your thicker wing performs.

I put my elevator servo in the tail and the rudder servo midships. I think the pushrod gives the servo a bit of a cushion from the tailwheel.

[Andy48]

Posted by Colin Naylar on 28/07/2011 23:09:48:

Hi Freeatlast ( from what? - the mind boggles)

 

Freedom from having to work for a living. Retirement means I can do what I want, when I want......within reason......

 

I did notice on the plan that you do not appear to be able to remove the front hatch because of the cockpit. 

Edited By Freeatlast on 29/07/2011 15:23:23

[Colin Naylar]

Oh right Freeatlast, you haven't just got out of Jail then

You are in good company, a good percentage of us on here are also 'free'

By the way, its always good to fill in your profile a bit on the forum so that folks know roughly at what skill level, etc to aim their replies. You could be a beginner or a show pilot!

Looking forward to following your Jitterbug progress

Colin

[Andy48]

Posted by Colin Naylar on 29/07/2011 15:31:46:

Oh right Freeatlast, you haven't just got out of Jail then

During the last few years of work, it felt like jail!

 

Will do the profile as you suggest. More or less a beginner, have just passed my BMFA "A", though reasonably comfortable with the building.

 

At the moment just making the wing template and have discovered the leading edge profile I bought is 3mm undersize. Aaaaaargh!

[Myron Beaumont]

Freeatlast

I used 1 cm square for my LE diamond shape as it was what I had in stock .Just cut a V in the ribs and fold the sheeting around the profile to the point and sand to shape when glue is set

[Andy48]

Hi Myron

 

Thanks for that. I am going to use the profile, but overlap the 3/32 sheeting onto the leading edge profile, and sand down the edge to the LE profile.

 

I've checked the dihedral braces. I think you are right here. I measured the angle on the plan and it is 3.1 degrees. This will give a dihedral of 1.7inches if my maths is right. The angle needs to be 3.6 degrees to give a 2 degree dihedral. (Those digital angle measuring tools are brilliant!)

 

I also notice the spacing of the wing ribs is anything but even. It varies from 72 to 75mm. You would think this would be easy to draw up. I cut a whole load of balsa webs all to the same size, and then had to trim them individually. Hey ho.

[Alex Whittaker]

JITTERBUG DECAL

Playmates, I've just reheated a dead hard disk and found a pdf version of the long lost Jitterbug decal. I think I've emailed everyone who wrote to me directly, but I can't remember who wanted one on this forum. Therefore I have asked David Ashby to put a copy up here as soon as convenient.

Hope this helps,

Alex

[Redex]

Hi All - new here, but been following the Jitterbug threads for the electric build tips, and this model looks really interesting. I have a QMS 4120 motor from a previous model looking for a home, so trying to see if this might be a suitable build.

 

What I would like to understand from the Jitterbug electric builders is, are there any preferred places as to where to mount the ESC e.g. to aid cooling or CofG balance and also in the case of LiPo's being used, generally do they extend through F2 or stop short - I have a spare Overlander 4S3900 which maybe a bit to wide for the F2 opening. Many thanks.

[Colin Naylar]

Hi Redex, Can't recall exactly what I did and the model is not easily available. I will check in the morning but I think I widened the F2 opening to suit the 4S lipo that I used. I don't believe I had a problem locating the ESC but I'll have another look!

[Andy48]

I'm in the process of building mine, just being doing the fuz this week, and I made a ply F2 former and had to widen it a bit to fit the same Overlander battery. It was already thinner than the one on the plans, so each side was reduced to 8mm. I have moved the motor mount forward so I do not need the spacer mount. I was thinking of putting the esc under the battery tray, and perhaps leaving a portion of the rear fuz base open near the tail to get an airflow right through the frame.

 

I have managed to make the tail section detachable, using the same system Seagull use on their trainers - 2 bolts accessed from underneath. This should make covering easier, and rebuilding (almost a certainty!!!) somewhat easier.

 

Next job is the front hatch, I am trying to simplify this a bit, and reduce weight.

Edited By Freeatlast on 26/11/2011 18:20:18

[Redex]

Thanks for the detailed responses - I did think about widening the F2 opening but I was not sure of the the impact, if any, on the structural integrity or how wide to open which may then allow greater selection of LiPo - seems to not be a problem using either balsa or ply.

 

Although I have not started building yet - I have made a mock-up of the front fuselage sides including F1 from some scrap, to check if the 4120 fits - seems OK but requires a slot in the under sheeting to avoid touching the can. I think this slot could be fashioned to form a cooling intake and with a small slot in the bottom of F1 would see air over the ESC mounted in the plans battery compartment - I did a cooling slot something similar for an electric WOT4 build. Other than that I was going to velcro ESC to side of fuselage somewhere between F1 and F2.

 

I have an E-Pioneer and the detachable tail section, works well for transportation - incorporating on the Jitterbug is beyond my build capability at present, but sounds like a really good feature.

 

 

 

.

[Andy48]

Having had another play today, I have realised that with moving F1 forward, the battery fits easily between F1 and F2. You do not need to make F2 thinner.

[Redex]

Moving F1 forward for me might also make the motor mount easier.

Just another question about the undersheeting - I am not sure what 'X-Grain' means and so far unable to find a direct reference for it. Is this just a medium density balsa with the grain running across the fuselage or something else (I'm trying not to ask to many questions here!!).

[Plummet]

X-Grain is not a new breakfast choice, it is short for "cross grain"

You are correct. The grain of the balsa runs across the fuselage. It curves easier that way, and it has the maximum strength keeping the fuselage sides the correct distance apart. If it was along the fuselage it would be more prone to splitting if pressure was applied to it.

Plummet

[fly boy3]

Hi Redex, you can ask as many questions as you need on this very helpfull forum. X is short hand for cross grain. If you look at a lenght of balsa the grain can be seen running along the length of it. On your fuz base, the grain will be facing across the fuz making it much stronger. Cheers