Here is a list of all the postings Grasshopper has made in our forums. Click on a thread name to jump to the thread.
|Thread: The Atom Special|
yes, I realise now the error of my ways! The old story - Saturday and Sunday the only flying sessions in the week right now, little wind for spin up so take a chance and then reach for the glue.
Not again though.
Yes that is Sam who is an excellent pilot and also, like me, enjoys experimenting with different types of craft.
Thanks for all your inputs which have led me to feel more confident now at being able to nail this next time out.
In retrospect my mate Sam has had some good long flights after hand launches whereas lacking wind for the spin up I have belted down the strip and it has self flown off but clearly at a rotor speed which was insufficient so I was rewarded by the 'snap left' and out came the glue.
Roll on Saturday when I can have another go. I will report back!
Graham, Rich et al, thanks for your input. I was unable to fly yesterday as it was raining, windy and cold. My visit to the club was not in vain as one of the chaps said he had video of one of my short lights. I have now looked at this many times and clearly the spin up is good but take-off occured probably before there was much lift with a resulting rapid bank left (stall?) and into the deck. Other tests gave the same result. I also noted that after the 'take off' applying full right roll to try to compensate did nothing at all, probably I guess as the blade speed/thrust was insufficient.
Over to Grahams nice clear email: I have just checked my pitch angle as he detailed and with the tail boom horizontal the neutral pitch is 6 deg to the rear which should be near enough? The pitch throws are +- 6 deg. The roll neutral is 1 degree left so less than Grahams and the roll throws are +-12 from neutral.
In my humble opinion then my initial attempts were doomed to failure as take off occured before the head speed was sufficient. What do we think?
Edited By Grasshopper on 16/03/2015 09:47:46
Edited By Grasshopper on 16/03/2015 09:48:06
thanks for the information. Your idle tilt is 3.5 degrees left and (I thnk) idle ptch is 5 degrees back?
My mate Sam and myself are runnung as follows
hang angle 16 deg
idle left tilt 1 deg
idle pitch 0 deg,
Sams Atom is not on AJ blades and he has had several good flights but thinks it needs more 'sorting' before it will be good.
My AJ blades are 460 long with bolt hole 10mm in from root end. I note that youir bolt hole is 25mm in. Might this be a problem on mine?
I am off to make some more tests in 30 minutes and will report back.
Edited By Grasshopper on 15/03/2015 08:28:13
I an using AJ blades with .4mm shims and so far my flights have been short - and not too sweet!
The spin up seems good but stability in the air is dire.
Hang angle is 15deg and throws have been very carefully checked.
Could changing to .8mm shims be worth a try?
|Thread: Completed Atom photo gallery|
Two more completed and maidened - out here in Brittany.
This is mine before some dodgy attempts to fly, now traced to 4 degrees up on the motor mount and now fixed.
This is my French friend Sams. He has made several flights but still wants to adjust things before he is happy.
|Thread: The Atom Special|
Two Atoms maidened this week here in Brittany.
This is Sams which he flew last weekend but found the roll settings too great. Retuned for today with zero pitch offset and +-4 degrees on the sticks and 3 degrees left offset and +- 10 degrees roll. Better but after a perfect landing in blustry wind Sam still reckons it needs some fine tuning.
This is mine in old-mans very bright paint so that I do not lose it. First attempt, take-off the ground with the blades making the right noise resulted in an immediate and rapid ground loop which broke the prop. Later, on a borrowed prop I tried a hand launch with the blades really pulling in the wind and it did an enormous loop with full forward on the stick. No damage but lots of questions.
Back at base I found the firewall was almost 4 degrees up and not 4-6 down which probably explains the looping tendancy!
Watch this space for next weekd session.
Edited By Grasshopper on 28/02/2015 19:35:05
Edited By Grasshopper on 28/02/2015 19:36:42
Another one has flown!
My buddy Sam flew his Atom yesterday for the first time here in Brittany. Almost no wind so initial attempts were tricky as we could not get the blades up to speed. Then after a run the whole length of our 'piste' off he went for a twitchy flight. This on +-16 degres of roll which was clearly too much. The wind was gusty just 20 metres or so up so he did well to keep control. Landing in a bundle in long grass with only minor damage.
My Atom needs some decals and the blades covering and I will be ready so looking at next Sunday for my maiden.
Edited By Grasshopper on 23/02/2015 19:03:20
thanks for that, very helpful.
Always the engineer I had hoped for some numbers to crunch but this is clear and I will do my setup and be ready for a first flight on Sunday.
My French friend Sam should be ready as well so we will have two Atoms at the field.
Interestingly there is a two seater autoogyro based on the airfield and apparantly the pilot offers demo flights. We often see him taking off and doing circuits from our patch which is only 300 metres from the big aeropland runway. Imagine that in UK.
David, thanks - I had spotted these throws a week or two ago, posted by Steve Jones.
Bear in mind that I talk about settings relative to the head plate as in my post above.
With his roll settings this gives 17 degrees left/right which on my Firefy is way too much for me. I use 8 degrees and find it flyable.
The tilt up is 17-7.5 = 9.5 degrees against Rich's value of 5 degrees.
The tilt down is -2-7.5=-9.5 degrees which Max 2 commented was 'noticebly more' than expected.
I am still not certain where this leaves us?
I must be losing the plot for having completed my build (less the painting) I cannot find Rich's throws in this thread and have only his build article to go on.
On my Firefly and Cranefly builds I have adopted the approach of setting the fuselage such that the mast is vertical in pitch and roll planes and in this way the various settings can be documented and applied without the need to allow for the mast angle since this is (almost) always fixed.
With this simple approach I think Rich’s settings are:
Tilt back 5 degrees.
Tilt forward ? degrees
Roll neutral offset left 1 degree
Roll + - ? degrees
Can anyone please confirm/modify these values and fill in the blanks?
I have been asked by a fellow club member to add his name to the Mass Build. We live in Brittany and fly at the nearby airport at Tremuson alongside the 'normal' planes. Sam, who is French and an excellent builder/guider follows the build thread and asked me to add his name. Job done!
My Atom build is nearly complete after a nightmare trying to get the motor cowl as I wanted it. Photos to follow soon.
What's the count now?
David, yes sounds about right. I buy my tonic in tins so will have to nip out tomorrow for a couple of bottles.
Clinometer on Android - yes of course.
Usual store, Google Play - program is by 'plaincode', product is Clinometer v 2.2 is what I have - and it's free!
Let us know what you think of it.
Also available for A**le.
Edited By Grasshopper on 31/01/2015 17:03:23
Having already made the canopy for my Atom using an empty water bottle and with the first one near perfect when I tackled the motor cover I expected the same. I have now tried about 6 different bottles but none of them will shrink enough to cover the tapered nose. What bottle did we all use here?
On another topic has anyone tried the app which turns your Android phone into a hi-tech clinometer? It is awesome and takes most of the guess work out of the head alignment process. Free to dpwnload so a real bargain.
My Atom build is well on after the (sadly!) obligatory Xmas break.
I am using AJ blades and about to glue the 4mm wide shims to the lower plate. I know that Rich had said that these should be 0.4mm thick but note that Steve Jones 2 said (page 50) that he had gone for 0.8mm as this gave a fast spin up but reduced lift. He had found that with 0.4mm the take off was at 60 degrees whereas with 0.8mm spin up was faster and take off perfect.
What do we all think - 0.4 or 0.8mm?.
|Thread: Unstable Plane With Camera on Top|
I have had problems with a small camera mounted on the wing of a slope soarer (2.1 metre Solius). It was mounted 2/3 of the way along the wing on Velcro and I had flown several times in moderate winds without problem.
On a day with little wind - so little lift, immediately after launch from a cliff edge I was scratching to gain some height so flying ultra slowly. Suddenly the glider went into a spin towards to camera and was almost lost. After landing safely (just!) the model was inspected by 3 or 4 people but nothing was found. I relaunched and the same thing happened again and this time I was able to sort of land among the cars in the car park.
The camera was removed and all was well!. We decided that at very slow speeds the wing was on the point of stalling and the camera caused that side of the wing to go first which precipitated the spin.
The weight of the camera cannot be ignored although at 19g on a 1400g glider the weight effect, although assymetric would be small.
Edited By Grasshopper on 19/12/2014 08:47:55
|Thread: The Atom Special|
thanks for the blade PDF.
I have balsa bashed all day and have all the pieces cut out and assembly started - so please add me to the list for the 'Mass Build'.
Peter Birnie - France
What's the count now?
|Thread: Fire Fly 2 autogyro build|
I have carefully measured the mast/boom angle and it is 10 deg. - the plan I measured as 9 deg. I assume this is the target value? I broke the original mast in a bad landing and had to dig out the base section. This error will lead to some latent additional hang angle, nose down but not the value I found this morning.
When hanging as shown with no LiPO I measured just under 25 deg. between horizontal and the boom.
In the nose is motor 2837/18 = 79g plus 30A esc.
Any thoughts on a work-round?
I have dug my FireFly out of the back of the hanger and started to check it over.
I find that with no LiPO the hang angle is 22 deg. and with a 3S1800 it is 27 deg.
The only way I can acheive 16-18 deg. is by adding 75g os so of lead to the tail which seems wrong.
Any suggestions please?
|Thread: Can you make any plane a sloper?|
Can you slope anything? My attempt was a Multiplex Mentor which had suffered a crash and buurning LiPO so no front end. Waiting for an eye op. so wanted an old hack to fly. A can of builders foam remade the front end, cleaned up the servos and added lots of leadup front and lobbed it off the local cliff in 20 kph wind.
It flew ok, just like a house brick and kept me happy until my eyes were fixed. Tomorrow is dustbin day though.
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