Flying the pulstar

[RON]

Has anyone flown their pulstar yet?
I had a go the other night and found it not too good.
Not sure if it’s something I’ve done wrong. Everything seems ok, wing is straight, correct dihedral, c of g bang on.
Symptoms are virtually no rudder response. Pitch is good.
Power is about right. Only thing I can think of is it’s quite heavy. Maybe my choice of wood for the wing.
I’ve just finished a new wing which is lighter and I’ve give it an extra half inch dihedral. Maybe it’s something to do with the power pod I’ve built as this isn’t on the plan.

Ideas?
I would like to hear other people’s flying reports.

Ron.

[Tobe]

The pod will increase the lateral area which would call for a slightly larger rudder. I have flown dad's and I feel that the larger rudder is of good help for a more positive control.

[Shaun]

The Pulstar will fly a little differently to your average single channel model. Its basically a powered chuck glider that you nudge around the sky. Check it glides straight with a steady descent before powering it up. If you find it turns left on power ok but not so well right ,then add a little right thrust to the motor. Also make sure the C of G is as per plan and you keep the model as light as possible. If you want a more positive response then as Tobe mentioned increase the size of the rudder a little.

Cheers,

Shaun

[_AL_]

I was hoping to maiden mine this Sunday but my prop hasn't arrived.
I might preemptively fit a larger rudder after reading this.

Al

[Mike_K]

Hi Ron

I've flown, crashed and repaired mine already!

I cheated a bit as I bought the iGull prototype from Neil, so only had a few minutes work to do. I hadn't got a suitable electric motor at the time so used my Cox TD .020 as per the original. I double sided taped the Rx and servo on the fuselage side and didn't bother with a fairing behind the engine (a mistake with hindsight - see later). I did recess the battery pack into the nose (a 4x 1/3AAA from my Alula glider). And I didn't cover it, just sprayed it with polyurethane varnish. Not pretty but it kept the weight down.

Shaun is spot on when he says it's really a powered glider. Actually I'd say a free flight glider with radio assistance, just enough to keep it in the field. I put about 30 seconds worth of fuel in, it climbs fairly fast under power then just glides down with lethargic rudder response.

After one evening session I got a bit bored with it, so modified it with a bigger rudder and and put some down thrust in so it didn't climb quite so steeply under power. That was far more fun. Later I tried spiralling it to get speed for a loop and it was too much for it, it suddenly had 90 degrees dihedral and it was coming down with the engine still flat out. Luckily not much damage as it came down in long grass, both dihedral braces had broken, the nose had a little split and I'd broken the prop. Five minutes with the razor saw had the old braces out and new 1/16" ply braces fitted (stronger than original and also the slot I'd cut was wider so had to be filled). A few seconds with the cyano had the nose fixed and it was ready again except I hadn't a spare 3-bladed prop. I've got some new ones now, but have to decide if I change it to electric so I can close the throttle if it goes pear shaped again.

Shaun suggested my wings were weaker than normal as I hadn't fitted the engine fairing on the wing, so that is a warning for everybody, build it like the plan... And it isn't really designed for looping.

I think there's potential to the model, both as a single channel model and as a multi with an elevator but with bigger control surfaces. I'm building a couple more from depron to test some ideas out, if they work I'll be on the phone to Neil for some laser cut balsa.

Cheers

Mike

The wings weren't strong enough to loop

[RON]

Thanks mike
Interesting read.

Sounds like you’ve had better luck than me.
I’ll persevere with mine and see what I can come up with.
I’ve enlarged the rudder slightly and built a lighter wing.
See how it goes.

Ron.

[Martin]

Mine's not ready to fly yet, but having read this thread, my theory is that the large side area of the fuselage below the wing counteracts some of the dihedral induced yaw-roll coupling that we rely on with rudder only planes.

I think a bit of extra dihedral coupled with a larger fin and rudder is the answer*. The larger fin helps not only by generating more yaw, but it also adds side area above the wing that counteracts some of the fuselage hanging below.

Maybe the original design, where the fuselage was made from 1/2 inch sheet, was less affected because it would be possible to round off all the fuselage edges to create a semi-circle cross section top and bottom. With our built-up box fuselages with gubbins inside, it's not possible to round off the corners to the same extent.

* Another answer, of course, would be ailerons - but they would not really be in the spirit of the original design!

[Tobe]

....what's wrong with single channel aileron?

[Shaun]

Been flying mine again today. Behaved well but it is important to get the motor thrust lines correct. I could replicate Rons situation where it struggled to turn right on power by not having any right thrust . You do need to get it trimmed out properly on the glide. My motor set up has plenty of go for the model on 2s but make sure the wing joint is strong on 3s.

It fly's as designed , being essentialy affected by the rudder but in retrospect a bigger rudder won't do any harm if you want a quicker single channel sport model type response.

Go for an aileron conversion Martin.. there were a number of single channel aileron only designs.

Shaun.

[Igull]

Go for an aileron conversion Martin.. there were a number of single channel aileron only designs.

Now that's very creepy - I was out flying for the first time in weeks this afternoon and was talking to another ancient modeller (we were around when Pontius was a pilot ) and the name Chris Grubb came up along with his friend Jock Cooper - both from Kirkcaldy up here in sunny Fife Chris designed 'The Banker' - Radio Modeller Mag - a s/c aileron model - I remember it being flown for the first time (I was only 5 ) - flew a treat and looked very smooth, not the least like a regular bang-bang rudder model. IIRC it was Jock Cooper that came up with the appropriate name
Maybe a Pulstar Banker might be an option - keeps the back end light if nothing else )

Cheers

Neil