Mini Plane

[Alex Brodie]

That looks really good. Bet it flies as well as it looks

[Robert Bromwich]

Hi Alex

Thanks very much 

2 months work to finish it, took me 2 days to cover it  

Have flown it for the second time on saturday(last saturday was maiden) and the people who were there said to me it flys better then it looks so thats saying something !!

maiden flight i didnt need any trimming at all not to bad for my second kit build

next flight i will get some video if i can get anyone to film it.

many thanks Rob

[Tim Mackey]

Congrats Robert...nice job

[David Ashby - Moderator]

Flown my Mini Plane about a dozen times now Rob, she's lovely, took me 3 months to complete so you were going some!

[Andrew Vaughan]

I've just recieved my kit now seeing your photo and reports of the maiden flight I am even more excited !

[Robert Bromwich]

Hi Andrew

you will love this plane ,as david has said takes about 3 months to finish but is well worth it

are you going glow or converting to electric !?!

well i think the hawker typhoon is my next build lovely looking plane

David just a quick question has the plan pack got the cowl, canopy etc in with it for the £90 or do you have to get the moulding set as well ??? just to make sure

Thanks Timbo and many thanks to everyone

Rob

[Andrew Vaughan]

Hi Rob

 Yes I am going electric, I am also going for mini servos for each aileron as he suggested, if you are electric as well did you need to add more nose ballast or did you find it ok ? I was planning on putting the 3S2P Lipo behind the firewall in front of the balance point. I should be able to access this via the cockpit and thereby keep the wings attached for battery changes. as well at keeping more weight in the front.

The kit comes with the cowling done all you need to do is stick the two halfs together, the canopy needs to be shaped. you do have to buy wheels but not the covers for the wheels.

 Also I 'm also thinking of the typhoon next

Frank 

[Robert Bromwich]

Hi Frank

yes i have gone electric and have uploaded a picture of what i did to get the batterys in.

I tried it the way you say you are doing it and could'nt  get C of G right and also could'nt fix the batterys down without alot of trouble but i have got the single servo for the ailreons so that was in the way where you will not have, the way i have done it no taking of wings takes me a couple of mins to change them so thats ok for me

Q: What motor are you putting in it ??

Are you using 3 cell lipo ?

just saying that about lipo as will only have 11.1v for a 5 1/2 IB plane

Rob

[Andrew Vaughan]

Hi rob

Below is the data from MotoCalc using a LiPo 3S2P (3cell) 11.1V. This software is normally pretty good and had the data for the miniplane already, with the empty weight. This report was also in line with what I have been told from two shops and a web site. So I am confident that this set up will work, though time will tell. The software allows a variety of set up to be tried so I will play with this until I am happy.

I was thinking of screwing some weight onto the front of the firewall if the battery is insufficient to sort the CoG, but I will relook at this in light of what you said.

Frank 

MotOpinion - Smith miniplane axi engine
394ft above Sea Level, 29.92inHg, 58°F

Motor: Model Motors AXI AC2820/8; 1500rpm/V; 3.3A no-load; 0.026 Ohms.
Battery: Kokam 3200SHD (20C); 3 series x 2 parallel cells; 3200mAh @ 3.7V; 0.008 Ohms/cell.
Speed Control: Generic Brushless ESC; 0.006 Ohms; High rate.
Drive System: Generic 14x10in Prop w/2.5:1 Gearbox; 14x10 (Pconst=1.31; Tconst=0.95) geared 2.5:1 (Eff=95%).
Airframe: Sig Smith Miniplane; 672sq.in; 83oz RTF; 17.8oz/sq.ft; Cd=0.047; Cl=0.3; Clopt=0.46; Clmax=1.11.
Stats: 77 W/lb in; 57 W/lb out; 21mph stall; 32mph opt @ 67% (41:17, 119°F); 40mph level @ 80% (29:19, 133°F); 1062ft/min @ 22.1°; -375ft/min @ -7.6°.

Power System Notes:

The full-throttle motor current at the best lift-to-drag ratio airspeed (35.5A) falls approximately between the motor's maximum efficiency current (36.4A) and its current at theoretical maximum output (202.8A), thus making effective use of the motor.

Aerodynamic Notes:

The static pitch speed (51mph) is within the range of approximately 2.5 to 3 times the model's stall speed (21mph), which is considered ideal for good performance.
With a wing loading of 17.8oz/sq.ft, a model of this size will have trainer-like flying characteristics. It would make an ideal trainer, for use in calm to light wind conditions.
The static thrust (64.5oz) to weight (83oz) ratio is 0.78:1, which will result in very short take-off runs, no difficulty taking off from grass surfaces (assuming sufficiently large wheels), and steep climb-outs.
At the best lift-to-drag ratio airspeed, the excess-thrust (31.6oz) to weight (83oz) ratio is 0.38:1, which will give strong climbs and rapid acceleration. This model will most likely readily loop from level flight, and have sufficient in-flight thrust for many aerobatic maneuvers.

General Notes:

This analysis is based on calculations that take motor heating effects into account.
These calculations are based on mathematical models that may not account for all limitations of the components used. Always consult the power system component manufacturers to ensure that no limits (current, rpm, etc.) are being exceeded.
 

[Robert Bromwich]

Hi Frank

Looks like you have got it all sorted

I've only used motocalc a few times and like you said works great but i like trying to work it all out myself gives me a good challenge and for the planes i have done this on i seem to be getting it about right

my mini plane has a 11 x 5.5 Apc which gives me 777watts @ 35amps

i have come to the conclusion that instead of dead weight in the front i might as well have power this is why i have it on 6 cells so have no weight in front at all

gives me vertical so takes off in about 10 foot on grass if that

Have done the same with a ripmax spitfire i have, instead of weight i used 2 x 3cell 2.2a in it so gives me 10 mins flights at full power but have flown it for 15 mins as flies at half power like scale speed

When you have started it please post some pics

Have you thought about final pattern yet ?

Rob

[Andrew Vaughan]

Hi Rob 

I like the thought about the extra power and it had crossed my mind as well. when she flys is she twitchy or stable as a club mate was concerned about this.

when I get more done then I will post some pics, as for the final pattern I was going to do some research into this later in the winter. At present we are still getting good weather so I have been down the field

Frank

[Robert Bromwich]

Hi Frank

flies lovely she is not twitchy and is as stable as any of the other planes i fly ,easy to land etc shouldn't be a problem to any intermediate flyer's (if i can fly and land it anyone should be able to)

just a thought for you if when you have finished building if you find you cant get the balance right how about using 2 x 3200 3 cell lipos ,so keep it on 11.1v but you will double your flight times 10 mins full !?! of course you would have to see what the weight differance was but could work

i am using the DX7 tranny and what a system that is ,it's great

All i can say is when you have built and flown this plane you will fall in love with it and want to fly it all the time like me !! ,it's no wonder Sig have been making this model for 30 years

Rob

[David Ashby - Moderator]

Here here Rob, love mine (sorry been away a few days) to bits. I popped a two-stroke .46 in but will re-engine with a four-stroke this winter. My review of the model is in the special issue of course....

 David. 

[Robert Bromwich]

Hi david

have'nt had chance to flt mine again yet (weather and work) but hopefully will soon

Have just ordered the hawker typhoon so can't wait for that to come  girlfriend getting it me for christmas but i'm sure i can get around her so i can start it before hand.

Is there anything Tony had wished he had changed on his typhoon build before i get around to starting mine ,just thought i would ask??

Have'nt got any petrol(glow) planes or heli's i find them to messy and electric to me is a lot better and easy to do

Rob

[David Ashby - Moderator]

Yes I'm nearly all electric apart from the Mini'

I'll speak to Tony soon so I'll ask him but so far I'm not aware of anything he'd change from our previous conversations. He seemed very pleased.

David.  

[Tim Collins]

Hi I am building my Mini plane at the moment, after reading David's article last year. It arrived at christmas and it was started in April. I am about to build the wings and then I will be down to finishing. My question to anyone is what paint can I use to paint the cowl and solarfilm once applied. I have been looking at solarlac as a possibility. I spoke to a fellow club member who recommended not painting the solarfilm as it would crack. I would like to achieve a good match on the cowl etc. Could you let me know it would be appreciated?

Any suggestions from futaba against the HS 81s?

Tim

[Robert Bromwich]

HI Tim,

I used Prymol 'etching primer' on both the solarfilm and cowl any plastic or metal surface as well then you can paint or spray both with spectrum paints if you go to balsamart's website they have them both on there under section 'coverings & finishings'

Any suggestions from futaba against the HS 81s? not sure what your asking here HS 81's are very good servos but futaba also make good servos as well

hope this helps

rob

[Tim Collins]

Thanks for the info Rob, looks like this will be the way to go. 

There is a great feed on rcuniverse.com and also some good video on Myspace.  

 I will go back to sanding now.

thanks

Tim

[David Ashby - Moderator]

Hi Tim, been away and just caught up with threads. I painted my cowl with JP spray colours which match the Profilm colours and then sprayed a coat of fuel proofer (nitro-block I think it's called)

Good luck with yours, let us have some piccies when you've got a moment. I initially flew my model with a .46 two-stroke but have put the model in moth balls until I can find a nice four-stroke which on reflection I think would be preferable.

[Tim Mackey]

E - L - E - C  -T - R  -I  -C

[David Ashby - Moderator]

well yes funny you should say that Tim, I've just the right motor sitting here too.......

[Tim Mackey]

[Robert Bromwich]

David Go electric as Timbo says you will not be sorry

Just on way out to the field,im learning to fly heli's can hover but just getting the hang of forward flight it's more thrilling then flying new plane well at the moment anyway

Rob