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Author Topic: Peck Peanut Pietenpol G-24 powered  (Read 2468 times)
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FFmodeller
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« Reply #25 on: November 20, 2016, 06:59:06 PM »

I see no sins Jacques du Scalpele ... nice work  Smiley
« Last Edit: November 20, 2016, 07:19:01 PM by AeromodeLISTA » Logged
Pete Fardell
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« Reply #26 on: November 21, 2016, 03:09:53 AM »

Looking very nice, Jon! I've never been much of a Pietenpol fan, but you're changing my mind.
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Jack Plane
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« Reply #27 on: November 21, 2016, 01:34:42 PM »

Very kind words, boys.

Video of the full-size Piet I'm (roughly) modelling, a Model A Ford powered version built by the guy flying it:

https://www.youtube.com/watch?v=MiLcMV7N8r0

Aim is to have it ready for next OFMAC indoor meeting at Berinsfield on Sunday.

 Smiley
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ZK-AUD
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« Reply #28 on: November 21, 2016, 02:09:16 PM »

Wow I loved the video and that beautiful Chauviere prop made me come over all goosey!

Might have to put this on the list - I actually have a nice 10" Chauviere I carved a while back but never put on the front of anything....
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Jack Plane
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« Reply #29 on: November 26, 2016, 10:02:53 AM »

All done - except for registration letters on tail, and I'm pretending the markings on the stbd fuselage side don't exist!
All Esaki surfaces given one coat of non-shrinking dope thinned 50%
Final weight 15.2g (9.4 airframe, 5.8 motor) plus 0.7g tail-weight to balance = total 15.9g, so a loading of 0.53 g/sq in.

This is about 15% more than expected, on top of what I always reckoned would be a heavy plane for its limited wing area.
The kit wood tended to be stiff and so a bit heavy, and I could have taken more care with the rad and bulkhead weight etc.

But I'm chuffed enough as this is my first complete Peanut, and first working CO2 model.  Cheesy

Test glides in the garden showed the need for a bit of breathed-on up-elevator, and a marginal increase in tail-weight.
Test flights under power in the village recreation ground were tricky as it was damp and a bit gusty and the grass was wet.
G-24 set to run for up to 25-30secs on a 5sec gas-only charge, which seems to give about 15-20 secs of reasonable thrust before tailing off.

I tried all sorts of settings, see three short videos here https://goo.gl/photos/c9nG1rBX8TjQggSFA
But ultimately the initial power burst has a lot of left-torque, so (despite the right-thrust built in) I needed to breath-on some wash-in on the left wing, with a smidge of left-rudder for left circuits.

Will see what tomorrow brings indoors...

Smiley Jon

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Re: Peck Peanut Pietenpol G-24 powered
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Re: Peck Peanut Pietenpol G-24 powered
Re: Peck Peanut Pietenpol G-24 powered
« Last Edit: November 26, 2016, 10:14:12 AM by Jack Plane » Logged
Pete Fardell
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« Reply #30 on: November 26, 2016, 01:21:37 PM »

It's lovely, Jon. Great job!

(Needs a pilot though  Cheesy)
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DHnut
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« Reply #31 on: November 26, 2016, 02:24:06 PM »

Jon,
       The model looks very nice and I think the weight is about right. The weight penalty of the longerons is very little for the increased security of having sufficient strength. I watch the videos and the impression is that the power might benefit in being reduced, and a tab to hold the left wing up would be a possibility. Also using a prop with less pitch is another option. I have found that it is easy to get to much throttle on in the initial trimming giving a short run and a much stronger power burst. Hope that helps.
Ricky
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Jack Plane
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« Reply #32 on: November 26, 2016, 05:17:29 PM »

It's lovely, Jon. Great job!

(Needs a pilot though  Cheesy)

Cheers Pete... and thanks for volunteering!!  Grin

Jon,
       ... the impression is that the power might benefit in being reduced, and a tab to hold the left wing up would be a possibility. Also using a prop with less pitch is another option. I have found that it is easy to get too much throttle on in the initial trimming giving a short run and a much stronger power burst. Hope that helps.
Ricky

Thanks Ricky, certainly makes sense from my experience this morning.  Will tickle back the throttle in tomorrow's indoor session.  The prop is that supplied with the motor, not sure what pitch.

A bit surprised at the lack of climb and steep glide, but the incidence is correct according to the plan, so maybe its just a draggy design and all.

Will see what happens in a dry and windless interior!
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FFmodeller
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« Reply #33 on: November 26, 2016, 06:01:20 PM »

The finished product looks even better Jon  Smiley

If it's of any help .... my peanut Piet has flown for over thirty seconds indoors,  but has always been too easily unsettled outdoors even on pretty calm days. I think indoors things will be different!
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DHnut
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« Reply #34 on: November 26, 2016, 08:39:02 PM »

Jon,
       I overlooked to mention that I have used the Williams brothers props with good results. They are flexible white nylon and seem to have less pitch and the small one is about 4.5" diameter. Where is the CG because it sounds as if it might be a little forward if there is a steep glide. I know it hurts to add tail weight.
Ricky
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Jack Plane
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« Reply #35 on: November 27, 2016, 05:38:05 AM »

Thanks Russ - of course I reduced the dihedral to 10mm from the plan's 15mm; always saw this as an indoor jobbie really.

Ricky - 0.6g of blue-tak on the tails-skid has already brought the CG to the correct point on the plan.  Will try a bit more indoors today, until the guide (or low-powered glide) is flatter, then replace with lead shot inside the rudder-post.

Pete - 'The English Patient' is now underway!  Cheesy  Roughly scalpeled squidgy foam wrapped in strands of cotton-wool and fixed with watery PVA which dried overnight.  The hardened shell seems soft enough to pinch to final shape with nose etc, then paint.  Expect about 0.5g final weight.

The bugger is that I did my back in at the damp rec ground yesterday; the usual lower spine place... aargh!  I was going to bring the Kid to Berinsfield as my ground-crew (literally!) but he's off to a cookery-school themed birthday party of all things!  So I can see a bit of of paracetamol-abuse to last me the day, an hour's drive each way.

Jon
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Pete Fardell
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« Reply #36 on: November 27, 2016, 08:03:36 AM »

Interesting technique! I'll reserve judgement till he's finished though!  Grin
I suppose you can put him in the rear cockpit and reduce the tail weight slightly (assuming Pietenpols are flown from both seats?)
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Jack Plane
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« Reply #37 on: November 27, 2016, 01:04:50 PM »

Back-seat pilot position, the Pietenpol.  The forward seat doesn't need a windscreen, the upright radiator serves well enough as such, as well a massive 'air-brake' in the model!  I imagine its not an easy aircraft for the front-seat passenger to get into; the pilot at least has the benefit of being able to hinge-up a section of the trailing-edge aft of the fuel-tank in the centre-section (see previous photo)!

Not a brilliant session today:  the Berinsfield hall is really just too small a space for a Peanut which needs to fly a bit fast to achieve lift.  Trimming was proceeding fine, but the damage caused to the structure when its kinetic energy got repeatedly stopped by the forest of table and chair legs around the perimeter became increasingly unacceptable.  Repairs to be properly carried out in the comfort of my modelling corner!  Shocked

The Petersfield Posse have it easy!
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Pete Fardell
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« Reply #38 on: November 27, 2016, 01:23:09 PM »

That photo shows just what tiddly little aircraft they are.

Sorry to hear about the damage. Don't you just hate chair and table legs?
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Andrew Darby
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« Reply #39 on: November 27, 2016, 01:59:54 PM »

Super job Jon

Sympathy with the leg damage, I managed to suffer the same with my Camel at Bushfields yesterday.... Cry

Andrew
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« Reply #40 on: November 27, 2016, 03:21:59 PM »

Super job Jon

Sympathy with the leg damage, I managed to suffer the same with my Camel at Bushfields yesterday.... Cry

Andrew

Commiserations Andrew, even though the full-size Camel excelled as a ground-attack machine!  Grin

Always good to have a group-hug, boys.

One thing I've noticed at Bushfield is that folk tend to fly lighter Peanuts, floaty Walnuts, anorexic Profiles and ethereal Microfilms in such limited confines.  Would be good if we could limit the forest to one half of the space...
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Pete Fardell
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« Reply #41 on: November 27, 2016, 03:46:53 PM »

I've put thin carbon rod in the leading edges of two my more recent scale models, largely to protect against the dreaded 'table leg crunch'. I think I might make this my standard practice, although from a weight point of view it's probably not really a sensible option on smaller models like peanuts.
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FFmodeller
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« Reply #42 on: November 27, 2016, 05:10:08 PM »

Sorry to hear about the damage Jon .... how were things looking up to that point?

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Jack Plane
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« Reply #43 on: November 28, 2016, 02:38:17 AM »

Pete - I like the carbon method!  Interestingly the wings on the Piet were absolutely fine, leading edges being made from Peck's most robust strip-wood, and all eight strut fixing points used reinforcing half-moons which held well.

The damage was - progressively - at all the fuselage strut locations:  first the aft cabane strut fixings came loose at their bases (head-on shock), then each of the wing-strut points (twisting shock as each wing in turn took the brunt of leg contact), finally one lower longeron snapped upwards at the rear undercarriage strut location (hard landing after a stall) tearing up adjacent tissue areas.

All down to too much kinetic energy in too hard and small a space for trimming, combined with lack of built-in 'give' to absorb shocks.

Russ - Difficult to tell how well trimming progressed, as the loss of rigid incidence happened early on (aft cabane struts), until only the forward cabane struts were holding the wing on at all!

Some calm days forecast this week, but near freezing so don't know how well the little 'steam-engine' will work outdoors!
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Pete Fardell
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« Reply #44 on: November 28, 2016, 08:00:56 AM »

Good luck with the outdoor trimming. I'll be interested to hear if the motor can cope at all with the cold.

 Strut point and undercarriage breakages are a real pain indoors- rarely serious, but they gradually destroy the trim and tattify the model. At least they do for me. The only person I know who can disintegrate a model, at power, full on into a wall and have it good as new, back together and flying well five minutes later is of course Derek Knight. No one knows how he does it though (beyond the fact that there's some kind of dark West Country witchcraft involved, obviously).
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Jack Plane
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« Reply #45 on: March 18, 2017, 07:35:01 PM »

A belated update:

The outdoor flying never happened - juz too cold and blowy over the last few months.

But did the repairs finally, added an acetate down-tab on the inside wing, got the CG back enough by adding 0.5g of lead to the tail, and had a much better indoor re-trimming session at Newbury today.

The little G-24 now set and running very sweetly (must keep injecting in a drop or two of sewing-machine oil every couple of tanks or so).

The intrinsic challenges are due to a relatively small wing-area with a 16g AUW, and the honking great radiator adding much drag and turbulent airflow over the rudder.  I also made life a little harder by building in less dihedral than the plan indicates.

However, after several flights, including a ROG, it became apparent that most of the remaining trimming issues are arising from way too much down- and side-thrust, 9 degrees and 5 degrees respectively Shocked  This, then, is my analysis:

The down-thrust is clearly preventing the model from climbing, especially so as it must surely be blasting air up the underside of the stabiliser, negating much of the up-elevator I've progressively bent in.

The right-thrust is necessitating too much left rudder, hence the down-tab on the left wing to prevent spiralling in:  but as thrust from the motor progressively bleeds away, the rudder becomes less effective, yet the wing tab is in airflow that isn't effected by the prop and so remains effective - thus the model straightens out well before the landing phase!

In this video we see the Piet do exactly this, crash-landing on my own table!  https://goo.gl/photos/6hZNjH5eYtVVBSFx6

I've now hacked the motor out and will re-install it with less excessive thrusts, say 4-5deg down and 2-3deg right - and try again!

Smiley Jon
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Fudo Myoo
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« Reply #46 on: March 18, 2017, 08:31:53 PM »

Looked like she was doing great on that last indoor flight until the unfortunate incident with the table at the end, John. Its a lovely looking model too, Peck make a couple I wouldn't mind trying myself Pietenpol included .

Would it be beneficial to make some form of adjustable engine mount similar to how the GizmoGeezer works vs a fixed one? I doubt it would add that much weight.

Oh, I believe the G-24 came with a 4 3/8" x 3 1/2" prop.

Dave
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Jack Plane
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« Reply #47 on: March 19, 2017, 08:20:18 AM »

Dave, although it looked okay-ish on that flight, it's actually flying quite inefficiently (too much of one thing to overcome too much of another etc, with all the elements fighting one another).  This is happening at higher revs and faster than it needs to to sustain level flight, and not climbing  despite the initial power burst.  It should really be capable of climbing out properly and cruising a bit slower and longer at slightly lower revs, before descending as the power finally decays - and that is what I'd like to pursue.

First thing to get right is the correct amount of down and right thrusts, then reduce up-elevator and left-rudder a bit, then adjust the wing-tab (if still needed), whilst keeping a close eye on CG position so she becomes neither stall-happy nor nose-heavy.

So, the motor is now out, the nose bottom cut away for access, the 1/8th balsa firewall hacked off, and a 1/16th ply replacement laminated from 2 x 1/32 sheet currently drying.  This will be trimmed to fit and glued in, which the three supplied tiny machine-screws will properly penetrate, and so enable shims to be inserted to adjust thrust-angles with much greater ease than my previous (stupid) idea to permanently glue in the motor's flange with whittled cocktail-stick nails through the thick balsa!

Still, it keeps me off the streets!  Grin
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DHnut
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« Reply #48 on: March 19, 2017, 09:12:02 AM »

Jack my commiserations. To much down thrust can really be hard to spot. When you gave the figures I was a little surprised. My Comper only has about 2 deg down and about 3 deg right side thrust, with left rudder to control the left turn. The initial run is straight and as the airspeed reaches a critical point you can see the the rudder kick in.
Also I recently added a Gurney strip to a Veron Luscombe Sedan of 24" span to the left wing to flatten out an over banked turn. It was about 3" long of 1/16" square, that gives an inconspicious means of trimming. It worked very well.
The damage to undercarriages is always a challenge and I have resorted to a torsion bar when possible especially when the weight is a little high and also reduce the size of the wire. I am using guitar strings for some models. Also Mike Stuart has some really good ides on his web site.
Ricky     
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« Reply #49 on: March 19, 2017, 10:53:23 AM »

Sounds like a much better way of mounting the G-24, Jon. Hopefully once you've got that sorted things will start to fall into place a little easier.

I know when I tackle mine I'm going to see if its possible to make a mount that will allow me to adjust it in-situ as the machine screws are tiny and I really don't want to be juggling those and washers Wink

I shall wait for updates patiently and hopefully learn a few things to boot Smiley
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