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Outdoor Free Flight Forum => Electric Power => Topic started by: USch on June 11, 2017, 12:59:06 PM



Title: E-36 Pulsar
Post by: USch on June 11, 2017, 12:59:06 PM
It is quite some time I would like to build a structure as used now in all duration FF classes, carbon D-box, carbon TE, balsa ribs with cap strips. Problem was for which class? Not to big a model, so it can be build fast and in any place, not to many complications and gimmicks, a model suited to be test flown without going to a big field (80km away from my home). Coupe d'Hiver was out of question because you need a lot of space for the 40+ second motor run.

Last year I had build a E-36 Pearl 202 just to "taste" the class and as an old F1C flyer liked it. Before beginning I defined some points to be included (hopefully) in the new model:
   - d-box structure
   - use of a "decent" airfoil, not the usual Lucky Lindy style
   - a clean fuselage without anything sticking out, if possible
   - use of a new, superlight motor COBRA 2203-2800KV, only 19g
   - making my own propeller
   - making 2 wings, one with traditional dihedral (about 10% of WS, the other with 5% dihedral and tip plates

That's it!
For the wing section I opted for the Midic 309 taken from Tapio L. suggestion.
First thing to start with was making the plug and mould for the D-box. In good old tradition the plug was made of balsa sheets, the once which will stay forever in the balsa box because to hard and heavy for any model. Only the templates are milled from fiberglass. To help laminating the d-box I opened the V by 5° so to have better access to introduce the cloth. Thanks to CAD this is any easy task. The mould itself is made of simple glass cloth to about 2mm thickness. The laminations I tried up to now are
carbon cloth 90g/m2 and 25g/m2 outside
and
carbon cloth 90g/m2 and Modelspan 12g outside

With both laminations the final weight for the raw d-box (500mm long, 38mm large) is around 8g, a little bit to heavy for an model of this size. But being the first one's I dont care  ;)
Here the first pic's

Urs


Title: Re: E-36 Pulsar
Post by: Konrad on June 11, 2017, 01:12:24 PM
I'll be following along with this build.

What I've learned is that it takes pulling a few parts out of any mold to get the weight and quality we want. I never get this right the first time.


Title: Re: E-36 Pulsar
Post by: USch on June 11, 2017, 01:29:55 PM
Right Konrad !!!
And that is the big difference to pure balsa bashing. You can go forever trying to do the thing better. No fear to use just this only one, good sheet of balsa for a certain job. A certain cloth remains the same weight even if you have to order some more  ;D

Next step was to order the rib set for 2 wings, laser cut, I'm getting lazy, and the preparation of the main spar. The very first spar set is made of
top and bottom runners 2x0,4mm carbon from root to tip, way to strong and heavy!
The second set is 2x0,4mm top main panel, 2x0,13 (actually cap strip format) bottom main and top and bottom tip. Infill 2mm balsa with vertical grain. This saves already more than 2g on the wing.
Wing warps, another argument. Not willing to prepare 4 building boards with the warps included, I will try to mount the wing half's offsetting them by, for now, 0,8mm difference to give the desired wash-in on the right panel. My laziness is also the reason for choosing a rectangular plan form for the wing.

Urs


Title: Re: E-36 Pulsar
Post by: USch on June 11, 2017, 01:38:15 PM
A few more pic's about my wing-building.
My way to keep straight and vertical the ribs during gluing and the first near finished wing, only half covered and waiting for a further supply of 5 my mylar  :(

Urs


Title: Re: E-36 Pulsar
Post by: Tmat on June 11, 2017, 01:48:58 PM
Urs,
I think 1 layer 90 gram/sqr/M is enough for E36/F1S.
What is the weight of the wing without covering?


Tmat


Title: Re: E-36 Pulsar
Post by: USch on June 11, 2017, 03:27:47 PM
Weight of the uncovered wing is 34g, at least 8g to much, but it's the first one.
The 90g/m2 cloth is to much anyway. And it is a open weave cloth so it will never get airtight without tons of resin. That's the reason for using either glass or paper outside. Now I ordered some unidirectional layup with 2 layers +/-45° of 19g/m2, maybe even that will need a "closure" layer on the outside, but at least it is only 40g.
Like to fiddle around  ;D

Urs


Title: Re: E-36 Pulsar
Post by: rivers on June 11, 2017, 05:42:47 PM
Urs,
Your workmanship is very nice plus your work bench is much neater than mine.

I think an uncovered wind weight of 26 grams is only needed for a model with relatively low power, and I would consider your 2203 motor low power. For a stronger motor such as a 2205 from a quad racer more weight is OK.

When you get to a finished process can I buy two sets of d-box shells from you?

Dick

 


Title: Re: E-36 Pulsar
Post by: USch on June 12, 2017, 11:45:05 AM
Just to put the record straight....
My work place is so cluttered that, if I would take the pictures on it, I would need to write a text book to explain what I wanted to show  ;) ;D
So better move to another, cleaner table.

Motors, on the Pearl I started with a Maytech 2205-2300KV, a Graupner Speed Cam prop 6"x6", the Nanotech 350mAh LiPo's and a YGE 12A controller.
Together with the COBRA's 2203-2800 I got also the COBRA 2204-2850 which I use actually. Height in 10 seconds is around 120m, nothing special, judging from what I read from Tapio L. and Airplay stating 180m. The bottleneck could be the controller. But to my experience an overpowered controller is cutting completely alimentation of the motor or at least starts with a rattle. Nothing similar happens, but for the sake of knowledge I will fit a 18A controller and see what's happen.

The Cobra 2203 is given for about 120W with a Graupner 7,4x4 folder. 120W is a good figure, but I could not try it yet. To many things to do, to little time....

Dick, no problem to send some d-boxes over the big pond, just leave me time to refine my techniques. I will PM you as soon as possible.

Urs


Title: Re: E-36 Pulsar
Post by: USch on July 05, 2017, 11:28:45 AM
No, I am not sleeping, but progress is slow. In the meantime I made more D-boxes with the new unidirectional carbon weave and the final weight is around 5,5g per wing half. But of course I already started the wing with the heavier D-boxes and will finish them for a first "proof of concept" model.

Here some mass production of fins and a first front end with carbon tube and pylon. The part in front of the wing will be shortened as soon as I finish the rear part so to put everything in place and cut the front to find the approximate position of the CG.

Urs


Title: Re: E-36 Pulsar
Post by: OZPAF on July 05, 2017, 09:08:28 PM
Interesting project Urs. Are you sure you will be able to keep this in your small flying field :)

John


Title: Re: E-36 Pulsar
Post by: USch on July 06, 2017, 09:58:00 AM
Are you sure you will be able to keep this in your small flying field :)

Well, here the new electronic devices come's in handy. Indeed, after some 30 years of absence from the FF activity, having now at hand electronic timers and RDT is like heaven  ;D 
I just keep constantly the 10 sec motor and the 2 minutes DT time and if anything goes wrong... one blip to stop the motor, another blip and DT, marvellous. Speed's up trimming a lot and saves models, can't ask for more  :P :P :P :P ;D

Urs


Title: Re: E-36 Pulsar
Post by: hastf1b on July 06, 2017, 10:16:27 AM
Are you sure you will be able to keep this in your small flying field :)

Well, here the new electronic devices come's in handy. Indeed, after some 30 years of absence from the FF activity, having now at hand electronic timers and RDT is like heaven  ;D  
I just keep constantly the 10 sec motor and the 2 minutes DT time and if anything goes wrong... one blip to stop the motor, another blip and DT, marvellous. Speed's up trimming a lot and saves models, can't ask for more  :P :P :P :P ;D

Urs


There is nothing to add.  :)


Heinz


Title: Re: E-36 Pulsar
Post by: USch on August 13, 2017, 08:10:14 AM
Back again.
The long absence is due a radical modification of the initial goal of just building a new E36. At one time I realized that I did not have (yet) the sensibility to dimensioning all this carbon stuff which goes into a wing like that. Of course I could have asked one of the Ukraine masters, but I dont have one in the neighbourhood  ;D. And discovering personally new things is not bad at all.

Here a short run-down on the 4  wings build up to now (#3 and 4 only left wing half's).

#1
D-box extends to 30% of the wing cord and is build with a 25g/m2 glass cloth on the outside and a 90g/m2 carbon cloth on 45°.
Spar is a 2x0,4mm carbon strip top and bottom with 2mm balsa spar web in between. Cap strip 1x0,12 and 2x0,12mm on all ribs. Full balsa fill between rib 1 and 2.
Weight of left wing 17g.

#2
D-box still 30% of cord, but with Modelspan 12g/m2 outside and the 90g/m2 underneath. Spar is 2x0,4mm on top of the main panel, tips and main underside is all 2x0,12mm. Cap strips on all ribs as in #1. Between rib 1 and 2 sheeting with 1mm balsa.
Weight of left wing 16,02g.

A little bit disappointing to gain only 0,98g. At this point I decided to go ahead and build some more (left) wings to see where's the potential to reduce weight even more. In the meantime I had got a new material, a mesh of UD carbon, laid down at 45° and superimposed at 90°, like a cloth laid on the bias. Weight of the mesh is 48g/m2. I did 2 sample boxes with 2 and 1 layer. Net result was a raw D-box with 5,5 and 3,4g weight, quite an achievement against the 7-8g of #1 and 2.

#3
D-box 25% of wing cord and the double layer D-box. Between rib 1 and 2 the D-box extends behind and has a fill up with vertical balsa to retain the bush for the wing hold-down screw. The bush has a very large disc to go over the main spar and transmit the forces to the fuselage-pylon. No carbon strip to hold the ribblets on the LE. Spar as on #2 but a little softer wood. Rib caps on the top is one rib full length alternated with only a short piece at the trailing edge. Bad idea= the weight gain is so small and the ribs remains so weak that it isn't worthwhile. TE is 3x0,7/0,5mm as on #1 and 2.
Weight of left wing 12,77g, getting closer   :P

#4
D-box 25% and single layer of carbon. Now this is a very thin D-box, it feels more like a paper rather than a carbon thing. But it is still extremely stiff. Would benefit from a lot more ribblets to avoid buckling. Spar is as per #2. Rib caps only on the intermediate ribs and none on the dihedral and tip ribs. TE is 1,6x0,6/0,4.
Weight of left wing 10,48g.

If I find the drive to build some more I will do it with the 1 layer D-box, double the ribblets now at 15mm distance and go to 8mm, add a 1x0,4mm strip on the LE, I am afraid the #4 wing LE will get damaged as soon it hits something on the landing. 13 more ribblets weigh only 0,3g! TE with 1,6x0,6/0,4 is more than strong enough for the job.

Now I have still to finish the #1 model to see if and how it fly's. Not being happy with the general lay-out I decided to redo also the tailplane and go to a 25% tpl to advance the CG to about 70-75%. The first 2 tpl where 30% which would have asked for a more rear CG in the region of 80-85%.

Urs


Title: Re: E-36 Pulsar
Post by: OZPAF on August 15, 2017, 02:00:19 AM
Very successful experimentation there Urs. Interesting stuff!

John


Title: Re: E-36 Pulsar
Post by: BG on August 16, 2017, 10:19:36 AM
Hi Urs,
nice work! thanks for documenting this. It will help me with my own efforts. I have a few questions for you.

When you make a D-box do you simply lay the carbon cloth in the female mold and then press this over the male mold?

I assume you clamp it down to get a nice even result?

How do you ensure you get most of the resin out of the cloth?

Do you use epoxy to attach the box to the riblets?

Thanks for the info.
Bernard




Title: Re: E-36 Pulsar
Post by: USch on August 16, 2017, 12:40:13 PM
Bernard,
you put your finger right in one of the most delicate question  :D

I can only describe MY approach, as there are many different solutions and how to do's, depending how much work you want to put into, what machining facility's you have at hand, what you have already in your workshop and so on.

As I wrote in one of the first reply's I choose to make a one piece mould. To work better inside the mould I did graphically "open" the shape by 5°. This could have been even more, say 10°, but that is the learning curve which teaches the trick's.
To press the layers I use exclusively vacuum, I did also a silicone male form but it did not work for me, trouble was not enough pressure on the whole surface and cloth sliding. Probably in combination with the silicone plug you need a 2 piece mould, just a guess. 2 piece moulds will have other problems as a flash on the parting line right on the LE radius.

For the lay-up I used two different methods, with the carbon cloth I staggered on the table (actually on a heavy, thick cartoon to not spoil the table)
1. micro perforated plastic
2. peel-ply 65g/m2
3. carbon cloth
4. light glass or light Modelspan
Then I flooded liberally with epoxy till the resin is impregnating all layers.
To transfer it to the mould I slide a 3mm wire between the cartoon and the micro perforated plastic in the middle of the rectangular wetted piece, place the mould with the open end over it and lift the wire till it touches the LE radius. In this way you do not move the weave. Inside the mould the perforating plastic is now the outside layer. On top of this goes a woven-non woven absorbing felt, about 3-4mm thick. And then you make the bag around it and pull out the air to about -0,9 bar.
The pressure from the vacuum compresses the carbon cloth and the excessive resin passes through the perforated plastic and soaks the felt.
The laminations from the carbon mesh I did without the peel-ply.
Then I place the mould in an oven at about 45-50°C for 24 hours. Afterwards you will have to take of the bag, the felt, the perforated plastic and eventually the peel-ply. The peel-ply is a somewhat delicate operation, always bend it over by 180° and pull slowly to not bend the composite to much and damage it.
Working on hard, non absorbing surfaces where I can apply full vacuum I never pick up excess resin (plotting) before closing the bag. The pressure will do that job quite well.
The riblets are given a slight coat of sanding sealer on the circumference to avoid excessive absorption of resin. Then a thin layer of resin is given to all riblets and the spar. The bone (spar with riblets) are placed in the carbon box and held firmly on the jig to take the right shape. BTW, old Coupe motors do an excellent job here.

Hopefully you can understand a bit of the process, otherwise just ask!

Urs
 


Title: Re: E-36 Pulsar
Post by: USch on August 19, 2017, 02:09:48 PM
First outing with the Pulsar this morning.
The battery is still outside the fuselage , this will be tackled later when I know where to place the CG.
The climb was sorted out quite easy, a bit of down and left, a bit of right rudder tab and it got on the rails. Not so much glide, strange, but CG at 72% seems to far back with a poor recovery from a bad transition. Now I either move the CG ahead or I change stab to the 30% one, still pondering  ???

But happy to see the new baby up in the blue sky  ;D

Urs


Title: Re: E-36 Pulsar
Post by: BG on August 20, 2017, 10:40:29 AM
Thanks Urs you response was helpful. Model looks good.
BG


Title: Re: E-36 Pulsar
Post by: USch on September 02, 2017, 07:38:29 PM
No trouble Bernard, just ask about the dark points  :)

I did not have much time to go out and do some flying, but did some homework on battery's. I had ordered from HK the Nano-Tech 350mAh cells. But as it happened I ordered the wrong pieces and got 6 single cell's instead of 6 2 cell packs. They were fitted with the BEC cable-connectors as in the first picture.

I thought that this was the ideal moment to measure the internal resistance of each cell and match them accordingly. Because the internal resistance is the single most important factor in a power class like E-36/F1S. The lower the resistance, the more power a given propeller-motor-esc will provide as net-output (and the less the cell's will heat up). C-rates given by battery manufacturer is actually a derivate from the resistance, but it is just to easy printing a number on a label, so dont trust the label, measure yourself.

Just to have a reference my 2 cell packs of 300mAh Nano-Tech cell's have around 80-90mOhm (mO), that means each cell has about half of that value. After the first charge-discharge cycle of the 350mAh cell I had numbers reaching from 120-220mO, 3 to 5 times the value of the smaller 300mAh cells, very disappointing to say the least. So I cycled each cell 3 times hoping in a run-in effect. But actually the resistance increased on each cycle!!! At a certain point I realised that this value had to do with another element, not the cell itself. So I took 2 cells, soldered them together as usual and fitted the 2mm connectors I usually use on this type of model up to 25A. This gave me the opportunity to fit smaller balancer leads and connectors instead of the clumsy connectors you find on commercial battery packs.

And woooow..... on the next cycle the resistance went down to 28-32mO/cell. Now that's an improvement against the 300mAh cell's, but at the expenses of an 10g increase in overall weight.

Moral of a long story, fit your system with the best connectors and change them as soon as they slide in and out to easy.

Urs


Title: Re: E-36 Pulsar
Post by: DerekMc on September 03, 2017, 10:07:48 AM
Urs, What connectors are you using in the second photo?  Thanks!


Title: Re: E-36 Pulsar
Post by: USch on September 03, 2017, 02:15:59 PM
Derek, I use the MC 2mm connectors from Multi Contact as in the picture. You have to cut them in half to form a male and a female connector to be soldered to your cable. There's a reason why I write down the manufacturer's name. Nowadays there are a lot of clones of all types of connectors on the market and they can hardly be distinguished. Few of us have the knowledge, the equipment and the time to measure details like the resistance of connectors, we all like to build and fly models. So the only thing is trusting somebody else who does the work for you. Many clones are quite ok for the fist few connections, both loose soon the contact force needed for 20A.

I still like the separated plugs to connect the battery. Today the XT30 with a housing for both contacts, should have about the same properties, lesser than 0,8mOhm, as the MC2  one. Your choice  ;)

For the balancer lead I use the Molex connectors with 1mm pin spacing. Actually they are left-overs from long gone servo leads.

Urs


Title: Re: E-36 Pulsar
Post by: DerekMc on September 06, 2017, 12:56:04 AM
Thank you Urs. Very helpful information!


Title: Re: E-36 Pulsar
Post by: Tapio Linkosalo on September 06, 2017, 03:44:20 AM
For 2mm bullets, I use connectors from HobbyKing. I used to buy ones with plastic housing, but discarded that, soldered the pins to the wires and then protected with plastic shrink wrap. Cannot find those connectors listed now, but these innards seem similar: https://hobbyking.com/en_us/2mm-gold-connectors-10-pairs-20pc-1.html

2mm bullets are practical to use and take little space. Preparing for flight I connect the minus and install the battery to the battery bay. the plus wires hand beneath the model and the bay. Just before the launch I connect the plus to, and am ready to rok!



Title: Re: E-36 Pulsar
Post by: USch on September 06, 2017, 05:10:59 AM
I am using the same procedure as Tapio to get ready for starting, that's why I like divided connections.

For the weight-sensitive between you. The pictures show 2 types of 2mm connectors with a weight ratio of 1:3. And E-36 is a weight-sensitive class! You may find a very illuminating post from Yak52 in the Bungee glider topic about span limited classes. The bottom line says you can only play with weight and wing aerea in such a class if you like to optimise the flight envelope.

Urs


Title: Re: E-36 Pulsar
Post by: USch on October 24, 2017, 05:35:22 PM
A beautiful October gave me time for trimming sessions without wind. Just up and DT, up-transition and DT...

I changed the tail-plane once again to the big, 30%, one and finished with a 85% CG. With the new nano-tech 350mAh batteries and the heavy Maytech 2205-2300KV motor it climbs quite well. Logging data's will follow.

Last weekend the first official outing at Crivelle-Turin for the annual CAGNARATA, a competition in which all free-flight classes, except F1C, compete together. I got in the fly-off together with a friend flying a F1Q. I did 3' 40'' from a 10 sec. climb, but the F1Q got some good air and did the full 6'. Anyway a more than pleasant result for the first competition.

A few pictures to show the atmosphere during the weekend.

Urs


Title: Re: E-36 Pulsar
Post by: hastf1b on October 26, 2017, 06:33:37 AM
Looks like David and Goliath.  :) 

Very good result.

Heinz


Title: Re: E-36 Pulsar
Post by: OZPAF on October 26, 2017, 06:07:31 PM
Hmm- he had you on span and area Urs - but it looked like fun anyway.

John


Title: Re: E-36 Pulsar
Post by: PeeTee on October 27, 2017, 06:45:04 AM
Urs

I remember it well, with Alessandro appearing in the last picture!! Did any Brits go this year as Gavin said he might attend ?

Peter


Title: Re: E-36 Pulsar
Post by: USch on October 27, 2017, 09:58:06 AM
No Brit's around this year, Peter, only a good number of French guys with F1B, Coup's and F1S.

Yesterday a shock wave hit me  :(
Measuring out my baby I discovered that the number one Pulsar weigh's as much as 172g! Makes a wing loading of 13,5g/dm2. Now I knew I had used all the heaviest components build to assemble the ship and even mounted the heaviest battery (2 x Nano-Tech 350mAh), but still the result was a shocker. On the other side I now have a good reason to keep going on with the project  ;D  Otherwise I would not have anything to do during upcoming winter  ;)

Now going down in the workshop to finish the master of the front fuselage....

Urs


Title: Re: E-36 Pulsar
Post by: airplay on October 27, 2017, 02:11:09 PM
I dont think 2 separate cells is kosher. But please inform me. I like your model and have similar ideas. Have just received some carbon  from R&G, aus Germany. Jens.


Title: Re: E-36 Pulsar
Post by: USch on October 27, 2017, 03:22:06 PM
I have found this spec for the batteries:
For F1S (E36)
3.S.2 Characteristic
Nickel Cadmium (NiCad), Nickel Metal Hydrate (NiMH) and Lithium (Li) batteries can be used. Only 2 cell Lithium batteries or up to 6 cell Nickel cells can be used. Other battery related specifications in 3.Q.2 apply.
and
3.Q.2. Characteristics
Nickel Metal Hydride (NiMH) and Lithium (Li) batteries can be used.
Lithium type battery packs must be in “as manufactured” condition with the covering around the cell surface. If more than one cell is used a balancer connector must be fitted.

Now my batteries are "as manufactured" with covering around the cell surface. I just changed the connectors as everybody does and fitted a balancer lead to it. The 2 cells are kept together with transparent tape, but I could also substitute it with a heat shrink tube.

Urs



Title: Re: E-36 Pulsar
Post by: airplay on October 27, 2017, 03:51:24 PM























Only sceptical course asking fellow F1S flyer about coupling 2x300mAh's in parallel...  

Jens



















Title: Re: E-36 Pulsar
Post by: USch on October 27, 2017, 04:55:17 PM
...in parallel  ???

and why mounting 2 cells in parallel? The rules dont allow it! You could use 1 cell with 600mAh capacity. But you would have the drawback to double the absorption going somewhere to 35-40A needing a big 40Am ESC. And bigger, heavier cables to connect batterie to ESC and ESC to motor. At the last it will be difficult to find a motor which can absorb 40A at 3,5V.

Urs


Title: Re: E-36 Pulsar
Post by: airplay on October 27, 2017, 05:27:18 PM
Sorry for the confusion. I'm talking 2 300mAh 2s in parallel as I do in my rc soarer. I have many of these batteries and their accumulated capacities would come handy for the newer drone motor possibilities for F1S.                                                                                                                                                        Jens   


Title: Re: E-36 Pulsar
Post by: USch on October 28, 2017, 11:45:37 AM
Whilst looking the tennis semifinal at Basel between Federer and Goffin I had time to take some numbers on PULSAR-1 to keep you informed.

Wing 890x140mm projected (on the paper I had 910mm span  ??? ) = 12,46dm2
Tailplane 400x100mm = 4dm2
Weight in flying order 172,3g
FAI wing loading 10,5g/dm2, real loading 13,8g/dm2
Distance Wing TE-->Tailplane LE = 510mm
CG 120mm from LE = 80%

Wing incidence, measured from center of LE radius to TE = +3,35°
Tailplane incidence, measured from center of LE to TE = +2,3°
Total difference = 1,05°

Motor down 7,4°
Motor right/left 0°

Now next time I have to take some height measurements to have the kettle full.

Urs


Title: Re: E-36 Pulsar
Post by: USch on November 25, 2017, 07:26:40 AM
More progress is made as autumn and winter is approaching.

I finally finished successfully the mould for the forward fuselage part. Successfully because the weight of the first moulding was only 11,5g against the first prototype in balsa which weighted near 20g. And there is still place to better that result (I hope).

The composite is different in the motor tube and the pylon. The tube is a 90g/m2 carbon cloth outside and a UD carbon tape of 80g/m2 inside. The pylon instead is a carbon mesh of 49g/m2, rohacell 1mm and carbon mesh inside.

Lots of space to host the electronics inside the pylon, but I have still to find the best placement. The battery will be mounted from the underside of the motor tube with only the connectors outside. Hope to finish the model before the end of 2017 to start something else, a F1Q maybe?

Urs


Title: Re: E-36 Pulsar
Post by: BG on November 25, 2017, 07:45:20 AM
Urs can you show us the molding process that you used to make this fuselage?
thanks.
Bernard


Title: Re: E-36 Pulsar
Post by: USch on December 01, 2017, 01:55:24 PM
During the week I build another front end trying to avoid the errors of the first one. Lay-up is essentially the same as number one but I switched the layers on the tube portion. This time I put the high module fibre outside and the low module cloth inside. In the first pic the 6 pieces for the first part of work.

During the first step in the pylon I laminate only the outside layer of Carbonweave 39 and nothing else. Second pic is one half mould already inside the vacuum bag. Between the woven-non woven cloth I put a micro-perforated plastic sheet to separate things after polymerisation. Last pic is the bag with the vacuum applied. You can notice the resin penetrating into the woven-non woven cloth to extract the superfluous resin.

After dinner the second part of the story  :D

Urs


Title: Re: E-36 Pulsar
Post by: DerekMc on December 01, 2017, 02:00:34 PM
Urs, thanks for the pictures. It's nice to see your process.


Title: Re: E-36 Pulsar
Post by: Buster11 on December 01, 2017, 02:05:22 PM
Urs,

       Do  you find the carbon structure causes any problems with things like RDT (if any), or a tracker, even though the antennae are presumably mainly outside it?

Buster (We probably met at Säve in 1971 or other World FF Champs around then; I well remember your immaculate F1Cs)


Title: Re: E-36 Pulsar
Post by: USch on December 01, 2017, 05:14:27 PM
No, no.... the dinner didn't last 2 hours  ;D
but Mr. Microsoft decided it was time to do an update and blocked the pc till now.

Now the first part is done, I take the mould out of the bag and free the moulding from the woven-non woven cloth and the perforated plastic sheet. One thing to be very carefully is avoiding to loosen the grip between the mould and the composite, never pull at 90° to the mould but fold back 180° the material to take away and go slowly! The composite should never come detached from the mould.

Before doing the second part of the moulding I also clean the flash on the parting line including fibres reaching over the edge of the mould. It is done with the help of a cutter blade moving it against the mould and never away.

The second part of the moulding is the sandwich in the pylon, the rohacell pieces are prepared with chamfered edges. The inside is the same carbonweave used on the outside. This piece of fibre has to be impregnated on a plastic sheet, never  do it on the rohacell itself. Now you can put back the moulds in a new vacuum bag and place everything in a warm place (remember its winter time).

From now on its downhill, some test to place all electronic bits and pieces, a hold down for the timer. Maybe you wonder what the small window on the right hand side is for. I use the Sidus timer and communication between timer and programmer is by infrared rays. At the last the 2 shells (still in the mould!) are glued together and joined by a small glass tape over the seam.

Some pic's for a better understanding, 1 and 2 are to show  the rohacell inlay, the third is how to fill the inside of the pylon and the last the finished front end.
Weight of this second moulding is 9,4g, lighter than hoped for  :o ::) ::

Buster, what did you fly at that time, or what's your name?
Now I am not sure that with all this carbon everything will work ok. I am convinced that RDT will work well, GPS will be tryied as soon as I get one  >:( . The RDT antenna is sticking out a fair bit from the trailing edge of the pylon as shown in the picture of the balsa prototype.

Urs


Title: Re: E-36 Pulsar
Post by: airplay on December 01, 2017, 07:27:58 PM
USch, I just wonder how many grammes your complete carbon fuselage would end up in?

Asking, as I has same approach in my shop. I have made male plugs so far to mate with an conical tube. Why? More flexibility for electronics and stuff...
But I fear it might end up a bit heavy compared to my present balsa ones, with some carbon stringers. They end up about 20g with finn and all...

Jens
 


Title: Re: E-36 Pulsar
Post by: USch on December 03, 2017, 04:53:51 AM
Actually the composite front end is the lightest I have build so far. The first carbon tube-balsa pylon was certainly much heavier. I did a lot of data collecting but mostly for the wing. I can only estimate the real fuselage weight of the prototype by subtract the known weights from the total and the result is about 30g for the nude fuselage with a heavy tail boom.

Now I have 9,4g front end and 9,3g for the tail boom, fin and tailplane mount + the unknown 2-3g, so total weight should be around the 22g mark. This let's me think/dream of the 120g E36  ;)

Urs





Title: Re: E-36 Pulsar
Post by: USch on December 18, 2017, 11:23:09 AM
I added a clip to the inside of the pylon to hold the timer in place. To form it I used a piece of copper plate I had laying around and bent to the right shape.
Right shape means I had to mould a few pieces to get the shape right  :(
In the second pic you can hardly see the strip of cloth I put at about 20% of the pylon to strengthen the point where the wing platform will be glued.

Urs


Title: Re: E-36 Pulsar
Post by: USch on December 24, 2017, 11:49:21 AM
Nothing new to report from the south   :D

MERRY CHRISTMAS TO ALL OF YOU AROUND THE WORLD

Urs


Title: Re: E-36 Pulsar
Post by: OZPAF on December 24, 2017, 08:48:26 PM
MERRY CHRISTMAS to you as well Urs and thanks for all your interesting info and advice.

John


Title: Re: E-36 Pulsar
Post by: USch on April 15, 2018, 05:21:16 AM
3 month later......after a very humid and wet winter  :'( :'( :'(
No flying during a long period, but yesterday finally we had a go to the airfield with nice sunshine and no wind till 11 AM.

I did test fly the second baby of the family and now I can confirm that 180m+ are possible, see the graph attached. But as per now not regular, every flight is different. Looks as if stability is marginal and so if the model finishes the motor run with a nose up attitude it will loose half the height in the following stall. Will try next time to induce more turn during the climb. But with trim tab or with thrust line adjustment  ???

Urs


Title: Re: E-36 Pulsar
Post by: OZPAF on April 15, 2018, 08:31:52 PM
That's good height Urs! About the turn on the climb I guess I would prefer a bit of right tab and balance that with right inboard wash in? I guess it depends on the glide turn as well - assuming it is right/right trim. Perhaps a slight reduction in fin area?
However I must be clear that I'm not an expert in trimming but an avid student with a bit of success with CLG's.

happy trimming

John


Title: Re: E-36 Pulsar
Post by: duration on April 15, 2018, 08:40:37 PM
Urs,

Glad to see that it flies! From the photos of the pylon & motor tube (post #35) I was afraid that you had given up free flight and gone over to model submarines.

Louis

PS; Maybe I missed it, but do you have a list of component weights? 


Title: Re: E-36 Pulsar
Post by: frash on April 15, 2018, 09:04:02 PM
Urs,

Do you launch with your left hand?

Southpaw Fred Rash


Title: Re: E-36 Pulsar
Post by: Tapio Linkosalo on April 16, 2018, 09:40:18 AM
How consistent is the climb pattern? If it goes wrong, does it start ok and then veer off later? My Puzzle is quite sensitive to battery state, if the power fades then the climb pattern goes off. Large enough battery in good condition and fully peaked ensures good climb pattern.


Title: Re: E-36 Pulsar
Post by: Tapio Linkosalo on April 16, 2018, 11:04:46 AM

How consistent is the climb pattern? If it goes wrong, does it start ok and then veer off later? My Puzzle is quite sensitive to battery state, if the power fades then the climb pattern goes off. Large enough battery in good condition and fully peaked ensures good climb pattern.



Title: Re: E-36 Pulsar
Post by: USch on April 17, 2018, 02:53:27 PM
Here a breakdown of weights. As usual there was a surprise and at the end at least 5-6g I could not track down.

Wing 32g
Tailplane 4,8g
Fuselage 110,2
TOTAL 147g

The fuselage can be brocken down into:
fuse structure           27,2g
Cobra 2204           23g
NanoTech 350mAh   30g
ESC YGE 12A               6g
Prop                           4,6g
Timer                   3,5g
Servo D47                   5g
Motor mount           5g
Altis height sensor      2,4g
tail balance weight   3,5g
TOTAL                  110,2g

Fred, I dont know what you mean with southpaw, but I am surely a left-paw  ;D and launch with the left hand. Never got to launch consistently with my right arm (and I dont care).

And now about inconsistent climb and generally about small stability margin. During homework for a new model I run normally the Beuer formulaes for neutral point (NP) and stability margin for the CG. This model has the CG 7,5% in front of the NP. Looks like enough to my experience for fast power models. But the model often bunts during climb and I have to stop the motor via RC, could be underelevated. If the launch goes straight up it might stop in a nose up attidude and stall heavenly, loosing half the height, so again either underelevated or to small a static margin ??? But if one looks on the graph it stalls, but without increasing the amplitude. Turn during the climb is minimal, less than 1 turn in 10 sec, so next time I definitely will try to give 'em more circling power.

Urs

Louis, yes sometimes I play with friends with fast electric boats, but submarines........never  :o


Title: Re: E-36 Pulsar
Post by: Tapio Linkosalo on April 19, 2018, 12:22:50 AM
Never seen a E-36 bunting... so maybe your CG is too far back. Anyway, my experience of trimming Puzzle is that the decalage is the major feature dictating the turn rate of the climb. When I have the model turn too much I move CG aft and reduce decalage, and thus the model turns less tight. So moving CG forward should cure your bunt and also increase the turning rate. Prop side thrust may need to be adjusted too, but I feel that the "loopiness" of the climb induced by decalage is the first order feature defining the turn rate.
 


Title: Re: E-36 Pulsar
Post by: duration on April 19, 2018, 04:50:10 AM
Urs,

Thanks for the weight break-down. A total of 64 grams for the structure is very good. I doubt there is much fat left to work off, other than the 3.5g tail balance weight. An adjustable pylon might eliminate the need for weight at the tail, but the added weight of an adjustable pylon would probably be considerably more. 

The photo of the speed boat brought back memories of a plastic racing boat I had as a kid back in the late 1950s. But mine was powered by a small and weak electric motor---not very exciting. It did develop a leak, turning into a submarine---that was a bit more exciting.

Louis



Title: Re: E-36 Pulsar
Post by: USch on April 21, 2018, 11:40:48 AM
Went flying..... ;D ;D ;D ::)

Got up at 5.00AM to be at 7 on the field, pheeeeew.......
To follow Tapio's advice I drilled away 0,5g of tail-ballast to move the CG forward. But the real boomer was a flap to induce more left roll during climb. Still not really consistent as I like it, but sure on the way to it. The second shot of the flap is more to show you our nice flying field rather than the appendice. Third one is the result of the best flight at about 8.00 AM, no numbers to not shock anybody  ;)

Urs


Title: Re: E-36 Pulsar
Post by: USch on June 02, 2018, 12:53:02 PM
Hallelujah...…

after another month of flying (also winning a comp) and thinking, I tracked down the matter of bunting! A happy man  ;D ;D ;D 8) is reporting.

I had a dream and calculated the force the tailplane has to develop to keep the balance during climb. I knew the speed during climb, about 22m/sec against 4,5m/sec during glide. The force acting on the tailplane works out to be 25g which pull down on the tail boom. So I blocked the fuselage on the working table and put a 25g weight on the tailplane platform. The nice little tail boom flexes near to 5mm  :o :o :o and that means a change in incidence of 0,66°. No wonder the model bunts if it reaches a sufficient speed during climb!

How to stiffen the boom? First thought was to glue a rectangular carbon section, one on top and bottom. But on the finished fuselage it was difficult to fix the rods, keep'em straight and assure that it touches everywhere. So out came the spool of boron thread from which I made up bundles of 5 fibres and started gluing them on the boom with cyano, light and fast  ;D. After 3 tries (15 fibres) on top and bottom I thought to have enough rigidity gain to test the model. Because in the meantime my queer mind had worked out a theory saying that a little flex could be helpfull in the transition  ::) 

Today I went flying and it worked more or less as I had hoped for. One full turn in 10 seconds and a bit of bunt after 8,5 sec. Heights are always around 180-220m and sink speed about 0,55m/sec.

Urs


Title: Re: E-36 Pulsar
Post by: danberry on June 02, 2018, 06:02:38 PM
How does it do on the 5 sec motor? Do need to re-trim it to get a transition on 5 secs?


Title: Re: E-36 Pulsar
Post by: USch on June 04, 2018, 02:12:56 PM
I was so happy I had solved the question that I kept running 10 sec climbs. Mind, I did about 8 flights and recovery's, grass is by now about hip height so doing a recovery from 200-300m is eating your energy at a fast rate.

Next time I will certainly try 5 sec motor runs. I dont see any problems for the transition but that might be wish-thinking  ;)

Urs

PS: how comes nobody from your side of the pond writes what's going on in the USA?


Title: Re: E-36 Pulsar
Post by: PeeTee on June 04, 2018, 02:32:55 PM
Urs,it all seems to go on Facebook --which I don't use  ::)


Title: Re: E-36 Pulsar
Post by: USch on June 04, 2018, 02:35:58 PM
I'm afraid they have to do it without me too, no friend of FB and smart phones, just an old dinosauri.  :D

Urs


Title: Re: E-36 Pulsar
Post by: DerekMc on June 04, 2018, 03:30:10 PM

PS: how comes nobody from your side of the pond writes what's going on in the USA?

The main E36 developers in the USA don't post on Hippocket or Facebook.  I fly E36 but I'm not a developer of the class. I copy.


Title: Re: E-36 Pulsar
Post by: USch on June 04, 2018, 03:34:43 PM
Derek, you may not be a developer but you have one of the sweetest signature:

They fly better when you smile!
 :D ;D ;D ;D

Urs


Title: Re: E-36 Pulsar
Post by: DerekMc on June 04, 2018, 03:43:11 PM
Derek, you may not be a developer but you have one of the sweetest signature:

They fly better when you smile!
 :D ;D ;D ;D

Urs

Thanks!  I like it :D


Title: Re: E-36 Pulsar
Post by: PeeTee on June 04, 2018, 03:43:39 PM
 ;D ;D ;D

I like it!

Peter


Title: Re: E-36 Pulsar
Post by: OZPAF on June 04, 2018, 08:29:24 PM
Quote
The nice little tail boom flexes near to 5mm  Shocked Shocked Shocked and that means a change in incidence of 0,66°. No wonder the model bunts if it reaches a sufficient speed during climb!

Good one Urs. It bring memories of similar troubles we had with F3B models many years ago. This particular model was turning tightly on the speed course on cold days but in our hot summer sun - the turns were opening up for the same elevator throw.

After estimating the tail loads at speed - we did the same thing - stiffened the boom and the problem was solved. The heat was softening the epoxy on the tail boom, but it was still not stiff enough. We then had a standard test of no more than a 1/4 deg change at the tail for a 1 kg load.

It's a pity so much has moved onto FB -it's not a good place to have long discussions and even though I use it - it is very distracting.

John


Title: Re: E-36 Pulsar
Post by: danberry on June 06, 2018, 02:25:26 PM
I was so happy I had solved the question that I kept running 10 sec climbs. Mind, I did about 8 flights and recovery's, grass is by now about hip height so doing a recovery from 200-300m is eating your energy at a fast rate.

Next time I will certainly try 5 sec motor runs. I dont see any problems for the transition but that might be wish-thinking  ;)

Urs

PS: how comes nobody from your side of the pond writes what's going on in the USA?


The reason that I asked about the 5 sec run and transition ---

You are apparently going over the top as you approach 10 secs which leads one to think that you aren't up to speed at 5 secs. That would hint that a transition won't be wonderful at 5 secs and the 5 second motor run is all that actually matters in either event.


Title: Re: E-36 Pulsar
Post by: USch on June 06, 2018, 04:45:52 PM
Got what you mean, Dan. Next time I surely try the 5 sec. climb and report on it. It is quite probably that the models accelerates during at least 8 sec.

In the meantime I ordered some alu-carbon-alu tail booms which should be much stiffer than the Avia Sport Skinny we all use.

Urs


Title: Re: E-36 Pulsar
Post by: USch on June 17, 2018, 10:51:35 AM
This morning I made a new trip to the flying field to do five second flights and give the batteries some airing, otherwise they might get lazy  ;)

I did only 5 launches because they where so much similar one from the other that it seemed useless to go on. I had absolutely nothing to change, just up and away. Max. height was from 110-117m, very exiting  ;D ;D ;D

Looking at the climbs from below they did not seem to loose  altitude in the transition. Only looking afterwards at the graph's 4 out of 5 have some swoop at the top, but without heavy loss.

At the end of the month we will have a competition and probably I will fly it with 5 second motor runs.

Urs


Title: Re: E-36 Pulsar
Post by: OZPAF on June 17, 2018, 08:25:19 PM
That must be a nice feeling Urs. Boom flex most definitely the culprit of your earlier problems.

Good luck in your contest.

John


Title: Re: E-36 Pulsar
Post by: Tapio Linkosalo on June 17, 2018, 11:43:57 PM
Wow. To my eye looks like perfect transitions.


Title: Re: E-36 Pulsar
Post by: Duncan McBride on June 18, 2018, 08:21:05 AM
Double wow.  100+ meters on five seconds is tremendous. I have been trying to build E36 ships as close to the 120 gram limit as possible and use the smaller racing drone motors.  I was happy to see 90 meters on five second runs, but you have raised the bar considerably.  Great work, and thanks for sharing.


Title: Re: E-36 Pulsar
Post by: Tapio Linkosalo on June 18, 2018, 08:53:31 AM
I do not think that 120 grams is a target to aim too hard for. Several tests and simulations suggest that slight increase in weight does not impact glide much to mention, but if that 10 extra grams for a larger battery gives you 10 to 20watts more power, then that has a big impact on climb altitude. So a strong stiff model, powerful motor and large enough battery is the way to go!

110 meters on 5 seconds. Uhh. Way too much performance. I'd hate to go to 3/5 seconds motor run, but that is what the performance calls for.



Title: Re: E-36 Pulsar
Post by: DerekMc on June 18, 2018, 12:53:02 PM
Last I heard 120 meters is what Stan Buddenbohm and Ralph Ray are getting so you're among the best. Nicely done!


Title: Re: E-36 Pulsar
Post by: USch on June 21, 2018, 04:52:15 PM
As declared in the first post of this topic I wanted to learn and explore the latest technic of carbon D-boxes and carbon strip material for most of the wing structure. That meant also to do more than one model to get the feeling how to dimension the members and keep weight down. Right now I am flying with number 3 ship with a 32g wing which feels comfortable to handle and fly, the complet model is at 147g. If I could build a model with exactly 120g flying speed would diminish by about 0,4m/sec and sinking speed by 0,04m/sec. But the model would be rather fragile I'm afraid. Actually I wonder if it would be worthwhile. So I am weight conscious, but without exaggeration  ;)

Now I am finishing model 4 with a lighter wing of 26g, also the fuselage is 3g less, so I will surely be under the 140g mark, even if the new motor might eat some of this gain. Will see....

Conclusion, better a sturdy and stiff model and some Watt more on the propeller shaft  :P  ::)

Urs


Title: Re: E-36 Pulsar
Post by: USch on March 08, 2019, 01:48:59 PM
Some mod's for 2019.
I want to change the tailplane section to a flat plate. The flat plate has the steepest increase of CL, near the theoretical maximum at 2*Π*senα. And the increase is almost a straight line. So damping should be at his best  ::) ::) :P

Structure is made with a 2,5mm carbon tube as LE and balsa strips as spar and ribs, carbon covered. Weight 4,8g as the old one.

Now I have only to go to the flying field and fly....

Urs


Title: Re: E-36 Pulsar
Post by: Tmat on March 11, 2019, 02:27:08 PM
Urs,
I've tried flat plate tailplanes several times with F1B and never saw any superior damping features. I always went back to a standard flat bottom (or slightly undercambered) airfoil.
Let us know what you feel happens with your model!

Tmat