HobbyKing.com New Products Flash Sale
Reply
Thread Tools
This thread is privately moderated by Aio_1, who may elect to delete unwanted replies.
Old May 15, 2010, 05:58 AM
Registered User
bluey1982's Avatar
Joined Mar 2010
20 Posts
ok guys i have hit a problem.
Was sent a motor that despite being advertised as 16g it actually comes out at 27.5g and it will put the model over auw.
i am looking at some other lighter motors but have a question about prop sizes. if a 9.5g motor can produce 180-200g of thrust but on a tiny 4x2.5 size prop, does the smaller prop size matter?
cheers
bluey1982 is offline Find More Posts by bluey1982
Reply With Quote
Sign up now
to remove ads between posts
Old May 15, 2010, 05:08 PM
OSMBuddha
nagayama13's Avatar
KC Mo
Joined Mar 2007
784 Posts
kv has alot to do with it.....what kv is this 26g motor?
nagayama13 is offline Find More Posts by nagayama13
Reply With Quote
Old May 16, 2010, 12:57 PM
Registered User
Aio_1's Avatar
Ireland, Kildare, Leixlip
Joined May 2002
6,441 Posts
Yes, the prop size matters. The characteristics of the prop effect the speed, acceleration and braking of the plane. It also effects the airflow over the planes control surfaces. I'd recommend aiming for an 8" prop with a pitch of between 3" and 4.5" such as an GWS 8x4.3 or APC 8x3.8. However most props from 7" to 9" diameter with pitch around 40% to 55% of diameter should be fine on a typical sized F3P plane.
Because the swept area of a 4" diameter prop is much smaller (4 times less than an 8" prop) the speed of the airflow from the prop will be much faster. This will make the speed of the plane harder to control in addition to which you'll have much less braking effect in dives. You would almost certainly have very little aileron control in high angle of attack or hovering flight.

If you want to keep things simple and be sure of decent performance I'd suggest you stick with a motor that weighs 15g to 20g and will provide at least 200g thrust on say an 8x4.3 prop on 2s. The Hacker A10-15s is a good choice.

Aidan
Aio_1 is offline Find More Posts by Aio_1
Reply With Quote
Old May 17, 2010, 07:01 AM
Registered User
bluey1982's Avatar
Joined Mar 2010
20 Posts
Thanks guys, i think i am going to have to bite the bullit and get another motor. The turnigy 2204-14 looks ok and cheap.
whats the good watt range for say a 150g model? im thinking about 50-60w?
just weighed the model now painted and the bare airframe is 69g with the total electronics at 68g although i will be shortening all the wires etc. im frustrated because the all up weight on your index plans say 140g max and im gunna go at least 16g over that with the motor. i just can not see any way of building it lighter.
have seen some very light batteries on
http://www.alebproducts.com/index.php
does anyone know if he is still trading because i cant get through?
Aio, sorry this is not exactly on topic for the thread,
bluey1982 is offline Find More Posts by bluey1982
Reply With Quote
Old May 18, 2010, 01:15 AM
Love the sport, not the plane
Hawaii
Joined Oct 2009
1,233 Posts
Did you mill it?
dylantorquerol is offline Find More Posts by dylantorquerol
Reply With Quote
Old May 18, 2010, 02:32 AM
Registered User
Aio_1's Avatar
Ireland, Kildare, Leixlip
Joined May 2002
6,441 Posts
Quote:
Originally Posted by bluey1982 View Post
Thanks guys, i think i am going to have to bite the bullit and get another motor. The turnigy 2204-14 looks ok and cheap.
whats the good watt range for say a 150g model? im thinking about 50-60w?
just weighed the model now painted and the bare airframe is 69g with the total electronics at 68g although i will be shortening all the wires etc. im frustrated because the all up weight on your index plans say 140g max and im gunna go at least 16g over that with the motor. i just can not see any way of building it lighter.
have seen some very light batteries on
http://www.alebproducts.com/index.php
does anyone know if he is still trading because i cant get through?
Aio, sorry this is not exactly on topic for the thread,
That Turnigy motor should be fine. My planes weighing from 115g to 135g have max power of about 40W or 45W. I reckon 50W should be enough for F3P at the slightly higher AUW.
You're a bit overweight on the bare airframe. If I remember correctly I got a little under 55g for the airframe (depron, carbon and paint) before starting radio and motor installation on my lightest un-milled Index. Your extra weight could be due to the specific foam you're using, excessive adhesive or paint or a combination of the 3. I wouldn't worry about it too much for your first one. It'll fly faster than a lighter version but should still fly well and slower than most typical foamies.

It would be best to continue this discussion in the Index 2 thread rather than here. I'll leave this discussion up for a few days and then delete the off topic posts if no one has any objections?

Aidan
Aio_1 is offline Find More Posts by Aio_1
Last edited by Aio_1; May 18, 2010 at 02:44 AM.
Reply With Quote
Old May 21, 2010, 05:23 AM
Registered User
bluey1982's Avatar
Joined Mar 2010
20 Posts
Aio, you are probably right i suppose i was hoping for too much for my first attempt!
However, she has flown and i can report that i am slightly in love! what a cool style of flying! couple of cliks of rudder and she was hands off will try n get a photo of the little beauty on for all to see.
Even with my limited experiance of this type of model the index flew SUPERB! well done on a great design and thankyou!
(indoor masters here we come!)
bluey1982 is offline Find More Posts by bluey1982
Reply With Quote
Old May 21, 2010, 11:52 PM
Thanos Papantonopoulos
pappy69's Avatar
Edessa, Greece
Joined May 2007
439 Posts
hi all,

First of all congratulations to all of you guys building those nice f3p planes and sharing all those nice plans.
i have some questions which i believe you as specialists would easily answer. I am planing to build moreback and i was wondering what size of depron should i use?
6mm or 3mm with light FC enforcements as shown in the majority of your photos?

Thanks in advance
safe flights
Pappy
pappy69 is offline Find More Posts by pappy69
Reply With Quote
Old May 22, 2010, 09:21 AM
Registered User
bluey1982's Avatar
Joined Mar 2010
20 Posts
Hi pappy, although i am in no way a 'specialist' i think the morback is an all 3mm design. that will be my next project after i have thoroughly flight tested the index 2.2 i just completed (as soon as i get hold of more depron!)
good luck!
bluey1982 is offline Find More Posts by bluey1982
Reply With Quote
Old May 23, 2010, 11:03 PM
Thanos Papantonopoulos
pappy69's Avatar
Edessa, Greece
Joined May 2007
439 Posts
Thanks bluey1982.
pappy69 is offline Find More Posts by pappy69
Reply With Quote
Old May 24, 2010, 06:35 AM
Thanos Papantonopoulos
pappy69's Avatar
Edessa, Greece
Joined May 2007
439 Posts
It took me 6 hours to build this wonderful moreback and now it's done.
Another question is if there is a right and down thrust setup for this plane.
Does anybody have any idea?
As for the CG it's already answered (i believe the answer is to start it's 1 cm in front of the wing CF spar line).
Final weight is 88gr which i believe is not bad for a first time ever attempt to build a 3d depron plane.
pappy69 is offline Find More Posts by pappy69
Reply With Quote
Old May 24, 2010, 07:57 PM
Love the sport, not the plane
Hawaii
Joined Oct 2009
1,233 Posts
Did you build it with the VPP?
dylantorquerol is offline Find More Posts by dylantorquerol
Reply With Quote
Old May 25, 2010, 12:05 AM
Thanos Papantonopoulos
pappy69's Avatar
Edessa, Greece
Joined May 2007
439 Posts
nop! I used Depron
pappy69 is offline Find More Posts by pappy69
Reply With Quote
Old May 25, 2010, 12:40 AM
Phlathead
ToxicToast's Avatar
Roseville, CA
Joined Aug 2006
624 Posts
Quote:
Originally Posted by pappy69 View Post
Did you build it with the VPP? nop! I used Depron
OMFFF! This gave me a smile.

VPP=Variable Pitch Propeller

ToxicToast is online now Find More Posts by ToxicToast
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Depron F3P Plans please, can you Help? Jiffy Indoor Pattern/F3P 18 Aug 20, 2006 11:16 PM