JP TIGER MOTH 30

[Andy Green]

Some time back I won the monthly prize draw for the JP TIGER MOTH 30.

Well I finally got time to fly it the other day, and I was very disappointed.

It was a calm day with no wind to talk of, I lined her up and opened the throttle, (Max power by my meter is 280W) with in a few yards she was off the ground and that's when the trouble started.

It had a decidedly nose up attitued, that was power related, and the ailerons worked as if they were painted on. The throws are as per instructions. No aileron conrol at all, I only got it down by rudder, luck and a crumpled wing tip.

Now if this was one of my builds I'd have checked thrust lines / decalage / etc but this model looks so lovely it should have just flown working on the rule 'if it looks right....'

Has anyone else got one and what were your experiences.

I think the biggest disappointment was  expecting it to just fly, and it didn't.

Andy

[David Ashby - Moderator]

Sorry to hear Andy, downthrust required? Can you increase the throws?

[Andy Green]

Yes David - Increased throws and differential, but  I didn't mix any rudder in and yes agreed down thrust. required.

I did have a couple of goes.

I was wondering if anyone else has had a problem before I set to and set it up 'My Way'.

Andy

[Adam Chambers 2]

Andy,

Ive got the same model fitted with an sc30 and exactly as you experienced, it was awful to fly.

Despite me keeping things light as hell, she came out at 4.5llbs not the 3.5 claimed and just would not fly. A real shame. Ive written to JP to ask for comments as its clearly nothing I have done. Depending on the response, I may ask RCME to help me. £120 is lot of money for a dud model!!

I had to add a lot of lead to balance her , so you may need to do the same. Mine flew nose DOWN despite my balance being level. I needed full up to fly and she only managed a circuit before " landing" in the gorse.

 A very poor model.

[Ed Kershaw]

I've had one of these for over 2 years now (powered by an Axi 2820/12 with 12x6 APC-E prop and 3400 3s lipo - 300W setup) and it's had countless flights.  I've also got over 100hrs hrs on full size tigermoths.  As far I can tell, it flies a bit like the real thing, i.e. the ailerons don't do much and you need to balance turns with plenty of rudder (I use 50% rudder/aileron prog mixing).  Otherwise it's quite nice and looks a bit like a tigermoth in the sky, although it flies too fast to be that reaslistic.  You can actually fly it quite well on rudder only and just use the ailerons to level the wings on approach.

I did the electric conversion myself so I was in control of the thrust line.  Differential ailerons are a must - on the full size there is so much differential that the downgoing aileron (which doesn't go down much) actually starts rising again at full control throw.

I found the specified c of g was far too nose heavy - mine balances right at the back of the "fuel tank" (centre section), otherwise you run out of "flare" at the critical moment and it is then difficult to stop it tipping on it's nose, although a little burst of power can sort it out.  AUW is 1840g (just over 4lbs).  No additional weight was added to balance, just flight battery positioning.

Take-offs are more realistic with 1/2 throttle, otherwise it does tend to leap off the ground in a nose up attitude.

Personally, the only thing I really don't like about it is the awful fully symmetrical wing section.  Why did they do that?  It looks so stupid.  Also, it might have been nice if they'd sanded it a bit before covering it.

[Adam Chambers 2]

edward,

interesting as I suspect my cg may be very nose heavy. I used there cg location (110-115mm back from LE at centre) .

Ill rebalance mine the same as you to see if it helps. Mind you, you had the abillity to use a lipo to balance yours. I cant. I suspect this model was always intended for electric and not glow. At best I might shave 200g off loosing the lead up front but she still comes out a 4.5llbs!!

[Ed Kershaw]

Adam,

Judging by what mine's like, I would say it should still be fine at 4.5lbs.  It's got plenty of wing area.  I'm going to stick a camera in sometime without any qualms about weight.

One thing I forgot to mention previously is that I had to fiddle around with the rigging wires quite a lot at first to get the wings straight.  It's easy to rig it up with a warp if you're not careful.  My first flights were quite hairy now I remember it (that was over two years ago) because I hadn't bothered to rig it carefully.

 Also, hauling it off the ground early is a recipe for disaster - it'll end up nose in the air with no air speed and on the wrong side of the drag curve.  Under those conditions, it's very difficult to accelerate out of it.  On a full size you actually push the stick fully forward as soon as it starts rolling to get the tail up whilst it accelerates to flying speed, before rotating.  It's the same with the model, although it doesn't need full down elevator to get the tail up, just a small amount.

I would certainly not say the model is a dud.  Most people who see it fly think it looks great.  If yours only flies with full up elevator, something is definitely wrong.  The CofG of mine is 150mm from the LE of the centre section of the top wing - behind the rear cabane strut fixing.  Also, because it is balanced from a very high position, being out of balance doesn't have a dramatic effect of the angle it hangs at, unlike a normal low or mid wing model, so it is easy to make a false measurement.  A more sensitive measurement can be obtained by translating the CofG position onto the upper surface of the lower wing and balancing it upside down.  It's then like balancing a normal model.

One final point I would make:  JP claim this model can be used as a trainer.  I would strongly disagree.  I find it more difficult to take off and land nicely than my Goldberg Pitts!

Please let me know how you get on!

Regards, Ed

[Andy Green]

Thanks Guys

I've started to have a look at it, plently of down thrust built into the mount (for one awful moment I thought I might have fitted it upside down, but I hadn't) .

My CofG ended up at the rear of thr top wing so may have been too far back.

I must admit to not checking the wing warp and rigging wires - they were not tight and after the first bump slackened of a bit anyway. I've not given up yet, I'll have another go this week.

Andy

[Adam Chambers 2]

well I rebalanced her at the rear of the top wing centre section. ( Not sure how you got your to balance 150 mm back as the centre section is only 130mm wide!!!!  My instructions state 110-115mm back from LE., hence all the lead up front to do so.)

Shed a heap of weight and had to stuff the battery back a bit.

Take off was better, climbout steady but laboured and shallow, but as soon as I reduced power she just went into a nose down angle and piled in. Very odd.

I now know that the little sc 30 just doesnt like being inverted which didnt help. Jus not enough power.

Thats £120 gone, but a big learning curve consdiering this was my first artf. Ill stick to building instead !!

COULD RCME HELP OUT HERE ?

[Ed Kershaw]

 The reason I was able to get mine to balance 150mm back from the LE of the centre section is because the centre section's 155mm wide.

If your centre section's only 130mm wide, then I'm not sure we're all discussing the same model here.  Mine's a 7th scale 50" span JP Tigermoth - red fuz - silver surfaces - reg G-ARAZ - recommended motor SC30.  They also do a military version, I believe.

Also marketed by Green Models and Pacific Aeromodel.

Do JP do another one?

[Adam Chambers 2]

no its the same model but my measurements!!

 Just checked the instructions and it quotes cg as being 110-115mm back from LE.

[Ed Kershaw]

That's interesting!  My centre section is most definitely 155mm wide.  If yours is 130mm wide then it's a different model, even if it's roughly the same shape and size and JP are marketing it as the same.

A 130mm wide centre section would not fit either the wings or cabane struts on mine.

And if that dimension is different, then the model may well be different in many other respects which could explain why yours and Andy's don't fly very well and mine does.  I bought mine over two and a half years ago and it may be they come out of different factories now to a different design.

[Brian Webber]

Hi I have an unflown Tiger at present.It sure looks as if it will be a success!!

Hope I,m not going to be disapointed.Cof G needs to be correct as you are probably aware

Mine has only two sets of flying wires port and starboard as a Addendum for this model!

Hope to be able to report some good news,but thanks for the info anyhow.

[Adam Chambers 2]

whats your power source?

electric or ic?

[Ed Kershaw]

Brian,

 From the above, it would seem that there are two types of these models which can be identified, at least, by the width of the centre section.  Which type is yours?  Is the centre section 130mm (like Adam's) or 155mm wide (like mine)?

[Adam Chambers 2]

edward,

mine is the jp tiger moth . I measured the section incorrectly. Its 150mm wide.

[Former Member]

[This posting has been removed]

[Brian Webber]

  

       Adam..Power source ASP .30 4/stroke

       

        Edward..Centre section measures 85mmx160mm  Wingspan 50"

         Kit is from Pacific Aeromodel Mfg Inc..

         Sounds as if it could be from a different srable??

          Thoughts??

           Brian Webber

          

[Adam Chambers 2]

Brian,

Good luck!! Mine just never flew, partly as the sc just didnt like running inverted and partly because she weighed close to 5 llbs once balanced.

[Brian Webber]

  Thanks Adam,actually we have an Adam in our club with a Tiger Moth and will touch base with

him before any flying is attempted!

I have run the engine a few times and it seems reliable enough and suggests enough power

to fly this model!Suggested weight all up is 1.780kg.Mine weighs in at 1.82kg!Just under 4lb??

Will take it carefully for a while and see how I go!Its a beautifully constructed model and would

make me very sad to see it in a crumpled heap!! Instructions say CG 105>115mm from front of

leading edge centre section and it does balance there as they say!!

Brian

[Ed Kershaw]

Brian,

 It sounds the same as mine.  I think the same model is marketed under JP, Green models and Pacific Aeromodel, as is the Super Tigermoth 90.

My instructions also quote 105-115 cg (some seem to quote 110-115mm), although, as I wrote previously, my cg is a lot further back than that at 150mm.  Mine seems to fly better that way and spin recovery is no problem either, provided proper spin recovery action is taken.  It won't just recover by itself like most other rc models seem to.

From the above, some of these models appear to be a real handful and unfortunately we don't seem to have identified why this might be during this thread.  All I can say is that mine flys really nicely, the only vice being a tendency to tip on its nose at the end of the landing roll.  My rearward cg helps with this, though.  With the more forward cg, someone did suggest to me on landings that "it arrives like a plumbers toolkit" and I found I had to give it a burst of power at the end of the approach to initiate the flare.

 Please let us know how you get on.

Ed

[Brian Webber]

Thanks for all the info Edward.My weight all up is not far away from the suggested weight by the mgfers

although the little .30 4s is a weighty motor and C/G is slightly nose heavy at 115mm  measured from the leading edge of the centre section.Movement forward and aft doesn,t seem to make a great deal

of difference.Members at the club advise "just fly it".Easy to say when its not your model!!

Weather of course here at present  is mid winter and flying days are not frequent,however I,m not in any hurry and will be patient until summer arrives with more mellow conditions.I have plenty to fly in the meantime,hope to send photos soon!

Brian Webber