SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Dec 16, 2010, 01:11 AM
SPG
Sydney, Australia
SPG's Avatar
Joined Jan 2010
188 Posts
Hi All,
Need some advice. Maidened my EPP-FPV the other day and it was pitching down severely under power. The CG is on the front spar. And there is no thrust angle on the motor.
Any suggestions?
SPG is offline Find More Posts by SPG
Reply With Quote
Sign up now
to remove ads between posts
Old Dec 16, 2010, 01:31 AM
Registered Loser :)
mark hitchman's Avatar
New Zealand
Joined Sep 2009
1,928 Posts
Quote:
Originally Posted by SPG View Post
Hi All,
Need some advice. Maidened my EPP-FPV the other day and it was pitching down severely under power. The CG is on the front spar. And there is no thrust angle on the motor.
Any suggestions?
That is strange, I just flew mine after changing the motor and it is pitching up slightly under power, had to put in a small amount of down trim to fly under power. I was wondering why, now even more so. Just uploading the video to youtube.

Mark

P.S. Are you ailerons up, down or level with your wing?
mark hitchman is offline Find More Posts by mark hitchman
Reply With Quote
Old Dec 16, 2010, 07:06 AM
SPG
Sydney, Australia
SPG's Avatar
Joined Jan 2010
188 Posts
Quote:
Originally Posted by mark hitchman View Post
That is strange, I just flew mine after changing the motor and it is pitching up slightly under power, had to put in a small amount of down trim to fly under power. I was wondering why, now even more so. Just uploading the video to youtube.

Mark

P.S. Are you ailerons up, down or level with your wing?
My ailerons are level.
SPG is offline Find More Posts by SPG
Reply With Quote
Old Dec 16, 2010, 09:14 AM
Registered User
hobie14's Avatar
Western Europe 52.7° N 8.9° W
Joined Jul 2007
2,619 Posts
Quote:
Originally Posted by SPG View Post
Hi All,
Need some advice. Maidened my EPP-FPV the other day and it was pitching down severely under power. The CG is on the front spar. And there is no thrust angle on the motor.
Any suggestions?
Why not try some washers between the motor mount and firewall .....
hobie14 is offline Find More Posts by hobie14
Reply With Quote
Old Dec 16, 2010, 01:18 PM
SPG
Sydney, Australia
SPG's Avatar
Joined Jan 2010
188 Posts
Quote:
Originally Posted by hobie14 View Post
Why not try some washers between the motor mount and firewall .....
On the bottom (to tilt up) or top (to tilt down) of the mount?
SPG is offline Find More Posts by SPG
Reply With Quote
Old Dec 16, 2010, 01:27 PM
Registered User
Spain
Joined Jun 2009
81 Posts
[QUOTE=hobie14;16832535]Not very high around our club field due to local airport altitude restrictions .....


LOL
tumtum is offline Find More Posts by tumtum
Reply With Quote
Old Dec 16, 2010, 01:49 PM
Registered User
hobie14's Avatar
Western Europe 52.7° N 8.9° W
Joined Jul 2007
2,619 Posts
Quote:
Originally Posted by SPG View Post
On the bottom (to tilt up) or top (to tilt down) of the mount?
On the top ...... try one washer on each side at the top ..... see what you get ....... add another if not enough ...... take it in easy steps and rem loosen all screws when adding washers to the top so you don't strain the bottom screws ......
hobie14 is offline Find More Posts by hobie14
Reply With Quote
Old Dec 16, 2010, 01:54 PM
Registered User
cyhyam's Avatar
Highland, CA, USA
Joined Jan 2001
1,112 Posts
My 2 cents;

I just did the first trim flight, AUW 1450 grams, (added ballast to get CG, FPV equipment not in). I put the CG 1/8
behind the front spar = 28%. The motor is a Turnigy 2217 20 turn 860kv with a APC 11 x 4.7 slowfly. Full throttle
is 200 watts on 3S. The climb is quite respectable a maintainable 30 degrees in no wind. At full throttle is about 50mph
but that is a guess, I will be putting the GPS in next week.

I had been reading about needing 600 watt motors…only is you want to do 3D
cyhyam is offline Find More Posts by cyhyam
Reply With Quote
Old Dec 16, 2010, 02:08 PM
Registered User
hobie14's Avatar
Western Europe 52.7° N 8.9° W
Joined Jul 2007
2,619 Posts
Quote:
Originally Posted by cyhyam View Post
My 2 cents;

I just did the first trim flight, AUW 1450 grams, (added ballast to get CG, FPV equipment not in). I put the CG 1/8
behind the front spar = 28%. The motor is a Turnigy 2217 20 turn 860kv with a APC 11 x 4.7 slowfly. Full throttle
is 200 watts on 3S. The climb is quite respectable a maintainable 30 degrees in no wind. At full throttle is about 50mph
but that is a guess, I will be putting the GPS in next week.

I had been reading about needing 600 watt motors…only is you want to do 3D
have to say I was flying for a few weeks with 200 watts in the air and got fed up peeps saying my plane was underpowered .... mind you I was throwing it off a 1200 ft hill .....

Our club field is a totally different ball game if take-off is to the East ..... trees trees and more trees right at the end of the runway ...... having the extra watts is very reassuring and you dont have to use them ..... you can always fly through the trees .....

ps. doing 3D with a HK EPP FPV is an obscene thought ......
hobie14 is offline Find More Posts by hobie14
Reply With Quote
Old Dec 16, 2010, 06:17 PM
Registered User
cyhyam's Avatar
Highland, CA, USA
Joined Jan 2001
1,112 Posts
Quote:
Originally Posted by hobie14 View Post
have to say I was flying for a few weeks with 200 watts in the air and got fed up peeps saying my plane was underpowered .... mind you I was throwing it off a 1200 ft hill .....

Our club field is a totally different ball game if take-off is to the East ..... trees trees and more trees right at the end of the runway ...... having the extra watts is very reassuring and you dont have to use them ..... you can always fly through the trees .....

ps. doing 3D with a HK EPP FPV is an obscene thought ......
If the CG is too far forward it will require more power to fly.

Additionally a large diameter prop at a lower rpm will produce more thrust, like having a low gear in a big truck.

A smaller diameter at a higher rpm will produce more speed, but not as much "grunt" power.

With this design, big & draggy, we need thrust. You can get the needed thrust from a high KV motor with a small prop, but you will
burn a lot of watts doing it.

A low KV motor with a large diameter prop that is designed to be efficient at the lower rpm's will work best.
cyhyam is offline Find More Posts by cyhyam
Reply With Quote
Old Dec 17, 2010, 03:06 AM
Registered User
hobie14's Avatar
Western Europe 52.7° N 8.9° W
Joined Jul 2007
2,619 Posts
Quote:
Originally Posted by cyhyam View Post
If the CG is too far forward it will require more power to fly.

Additionally a large diameter prop at a lower rpm will produce more thrust, like having a low gear in a big truck.

A smaller diameter at a higher rpm will produce more speed, but not as much "grunt" power.

With this design, big & draggy, we need thrust. You can get the needed thrust from a high KV motor with a small prop, but you will
burn a lot of watts doing it.

A low KV motor with a large diameter prop that is designed to be efficient at the lower rpm's will work best.
Thanks for that ..... I have a few motors/props on order that may be suitable and will do some experiments ....
hobie14 is offline Find More Posts by hobie14
Reply With Quote
Old Dec 20, 2010, 07:33 AM
Registered User
Germany
Joined Dec 2010
7 Posts
My Setup

My first post here - Welcome to eberybody.
Yesterday i did maiden flight and i want to comment your post and present my setup:
Motor: Emax GT-Series GT2215/09
Prop: APC Elektro 10x5
CoG: around 10cm behind wing spar
Lipo: 3S 4500mAh seems to be ok - around 270W, but no "safety-power"
Lipo: 4S 4000mAh seems to be very comfortable for short take offs

Mine seems to be very tailheavy with smaller lipos without add. weight, so i do recommed bigger ones to get it glide. You must add addtional weight when using Lipos as mentioned on HK-Site. The motor is out of specifications with 4s, but runs nicely. Next ime i´ll measure the amps, should be around 400W with full throttle. You can climb easily with half throttle.
I´m very satisfied, with a correct CoG the plane is a very nice glider. See next weekend for FPV. I´ve the feeling that it can take a lot of cargo....Maybe my 3D-fpv-Setup?
Amaris2003 is offline Find More Posts by Amaris2003
Reply With Quote
Old Dec 20, 2010, 10:02 AM
Registered User
hobie14's Avatar
Western Europe 52.7° N 8.9° W
Joined Jul 2007
2,619 Posts
Quote:
Originally Posted by Amaris2003 View Post
My first post here - Welcome to eberybody.
Yesterday i did maiden flight and i want to comment your post and present my setup:
Motor: Emax GT-Series GT2215/09
Prop: APC Elektro 10x5
CoG: around 10cm behind wing spar
Lipo: 3S 4500mAh seems to be ok - around 270W, but no "safety-power"
Lipo: 4S 4000mAh seems to be very comfortable for short take offs

Mine seems to be very tailheavy with smaller lipos without add. weight, so i do recommed bigger ones to get it glide. You must add addtional weight when using Lipos as mentioned on HK-Site. The motor is out of specifications with 4s, but runs nicely. Next ime i´ll measure the amps, should be around 400W with full throttle. You can climb easily with half throttle.
I´m very satisfied, with a correct CoG the plane is a very nice glider. See next weekend for FPV. I´ve the feeling that it can take a lot of cargo....Maybe my 3D-fpv-Setup?
I fly mine for AP only right now ..... lipo is 3300 3 cell and 275g .... camera is 215g and if I don't fly with the camera I use both the top and bottom part of the canopy ..... I have 215g of ballast fitted into the top canopy when not carrying a camera so C of G is maintained .....

My view is I really think you need 400 watts minimum for this plane ......

look forward to your FPV videos .....
hobie14 is offline Find More Posts by hobie14
Reply With Quote
Old Dec 20, 2010, 11:07 AM
Suspended Account
United States, CT, Hartford
Joined Jun 2009
5,336 Posts
got mine and plan to mod it up a little. It's going to be painted a flat black ala Skunkworks but orange stripes on the bottom. Picked up some nice metal geared tower pro servos, and I'm going to cut flaps in as well. Finally, going with a Power25 and 60 amp efite esc. plenty of room for everything. I don't have the fancy FPW gear so I'm putting a SD card camcorder, flip, and point and shoot cameras up front. Also have 4-5 Cell batteries from 3300 to 5000 mah
porcia83 is offline Find More Posts by porcia83
Reply With Quote  (Disabled)
Old Dec 20, 2010, 01:41 PM
Sam in Virginia
sverlander's Avatar
Hampton Virginia
Joined Jul 2005
597 Posts
Quote:
Originally Posted by porcia83 View Post
got mine and plan to mod it up a little. It's going to be painted a flat black ala Skunkworks but orange stripes on the bottom. Picked up some nice metal geared tower pro servos, and I'm going to cut flaps in as well. Finally, going with a Power25 and 60 amp efite esc. plenty of room for everything. I don't have the fancy FPW gear so I'm putting a SD card camcorder, flip, and point and shoot cameras up front. Also have 4-5 Cell batteries from 3300 to 5000 mah
If you feel the need for flaps, why not use Flaperons?
http://en.wikipedia.org/wiki/Flaperon
Sure would save a lot of work and if you must paint it use as little as possible, too much paint can turn a good plane into a flying brick.
sverlander is offline Find More Posts by sverlander
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Help! how to fix this hobby king plane gazza2003au Australia 29 Mar 15, 2011 11:16 PM
Discussion Hobby King New FPV plane bignose13 FPV Aircraft 141 Nov 24, 2010 01:04 AM
Discussion New EPP FPV plane catamar FPV Aircraft 9 Oct 12, 2010 05:29 PM
Discussion Hobby King FPV help! Polarity for RX? Rooster433 FPV Talk 6 Oct 10, 2010 07:24 PM
Discussion Hobby King Christen Eagle Aerobatic Micro plane EPP Kit w/ Motor & ESC TopFoam Micro Ready-to-Fly 3 Apr 18, 2010 06:00 PM