question on f18

[kan0n]

erm..can know what the difference between
F-18 Hornet - Blue Angels (90mm Fan)

and


F-18 Hornet - Blue Angels (Twin)


intending to get this plane..but get confuse by the word "Twin"...

thank alot in advance

[jansonfinn]

erm..can know what the difference between
F-18 Hornet - Blue Angels (90mm Fan)

and


F-18 Hornet - Blue Angels (Twin)


intending to get this plane..but get confuse by the word "Twin"...

thank alot in advance

the word 'twin' could be meaning using 2 ducted fans

[blueangel]

looking for me ?

Check this out..twin - thats what it meant - two smaller EDF instead of single big one.

http://www.rc-warbirds.com/product_info.php/products_id/685

[Warbird]

Yes, the Twin version is 2x 70mm EDF fan, the 90mm version is 1x 90mm

[kan0n]

oh..thank alot..but can i know the pro and con of twin fan or a single 90mm fan..why divide into 2 kind? sorry..im new to this =/

[blueangel]

Personally, I would prefer a single motor because it is easier to work on. All else being equal.

But I don't know the advantage of twin EDF on a similarly constructed plane, since then with double motor and extra cables and maybe another ESC, the weight is an issue. But if it is faster with twin and you like faster jets, that could be the reason you should get the twin.

[jansonfinn]

Personally, I would prefer a single motor because it is easier to work on. All else being equal.

But I don't know the advantage of twin EDF on a similarly constructed plane, since then with double motor and extra cables and maybe another ESC, the weight is an issue. But if it is faster with twin and you like faster jets, that could be the reason you should get the twin.

my guess is twin EDF is used for bigger sized plane. Also have to depend on the fan size as well

[Warbird]

Guys,

In the case of the HET-RC F-18 mentioned in this post the Twin EDF uses two 69mm EDF units and the Single (90mm) uses one 90mm EDF unit.

Both planes are exactly the same except for the ducting and the power train.

In terms of price both can be in similar ranges or far of depending on motor brand, fan used and final power output.

Although the twin EDF uses 2 ESC's and 2 Motors, the single EDF uses a single larger motor and a single larger ESC plus a potentially larger battery pack.

As the efficiency of a larger fan is higher the performance of the 90mm fan plane at the same total output power (watt) should be slightly better then that of the twin version (if we neglect potential power losses due to the twin exhaust pipe).

Also due to the different ducting, only the 90mm version can be build with proper retractable landing gear. The twin 69mm version would be bungee launched or equipped with fixed gear.


Example of minimal power requirements:

Twin F-18:
- 2x 700 watt
Example: 2x 2W-20 Motor, 55A or bigger ESC with one 3700mAh 4S (22-25C) Lipo for each motor

A stronger motor for 5-6S lipos and 850-1100 watt or more will be much better.


Single F-18:
- 1x ~1300 watt
Example: 1x 600-42 Motor, 70A or bigger ESC with one 4200mAh 8S (22-25C) Lipo

More power with stronger motors (either through higher currents or higher voltage) will improve performance.
E.g. Lehner 1940-12HA at 8S or Hacker B50-13XL at 10S (current draw ~90-110A)


Speed:
Depends purely on your power setup. Both airframes are identical.