Discussion VTOL Halo Pelican? could it be done?

[onelastflight]

Hi everybody im new to RC groups, this question promped me to join. I rather like that pelican troop carrier VTOL aircraft in the videogame halo and i was wondering if it would be within the realms of possibility to make a proper flying model of it that flies like it does in the game?

For those unfamiliar with it heres a pic,

http://www.geocities.com/snipersoldi...s/pelican2.jpg

Ive trawled the internet in search of someone whos attempted this but to no avail. I dont have much experience with VTOLs, only with normal planes, but im guessing that this would be quite difficult because:-

it has four thrusters (one on each corner) which would probably have to be ducted fans of some sort

These would each need independent thrust vectoring if it were to fly like the real thing. so really complicated controls may need simplification

its rather bloated looking so keeping the weight down (which i know is important for VTOLs) whilst maintaining a scale appearance could be hard

Four thrusters would be an unconventional control layout, could be a nightmare rigging up gyros

Im thinking the easiest way to attempt this would be keeping it fairly small, depron construction like a shock flyer, have it mainly for indoor but outdoor when its reasonably calm, use four micro edf units probably a single large esc and 3s LiPo somewhere between 700 and 1500mAh size. Of course theres more to it than that and im hoping to learn more about VTOLs along the way.

What do you think, am i crazy or is it doable?

[RCvertt]

Originally Posted by onelastflight

Hi everybody im new to RC groups, this question promped me to join. I rather like that pelican troop carrier VTOL aircraft in the videogame halo and i was wondering if it would be within the realms of possibility to make a proper flying model of it that flies like it does in the game?...

What do you think, am i crazy or is it doable?

I'm afraid your crazy but for all the right reasons as it looks like a cool aircraft.

The main problems is see would be the use of ducted fans. They are about half as efficient as props with regard to static thrust, which is what you want for hovering.

This will result in flight durations that are about half of what you would get with a similar set up that uses props.

It's not the most accurate analogy but I think of comparing ducted fans to props for use in VTOL as comparing 1st or 6th gear in a car for use when driving up a steep hill. Ducted fans are great for speed but not so much for power/static thrust.

The second issue as you pointed out is that thing is just carying too much dead weight by how big the fuselage is. Even all depron probably won't be light enough.

The last issue I see has to do with the size of the craft again. It's surface area may dampen your pitch controlls too much when hovering.

Having said all of that I hope you give it a try.

[Wings of War]

the hornet, would be easyer http://nikon.bungie.org/bwu/images/hornet.jpg

[PieJesu]

I'm new to RCGroups too *yay*

I think this is possible but as RCVertt says, EDFs wouldn't be the way to go with this one.

The hornet looks better though!

[atmk]

Originally Posted by PieJesu

I'm new to RCGroups too *yay*

I think this is possible but as RCVertt says, EDFs wouldn't be the way to go with this one.

The hornet looks better though!

while less efficient i still think that ducted fans must be used to maintain sale appearance. 4 ducted fans would be fully capable of lifting the pelican (lipo's+brushes motors = it will probably fly(even if its a brick)) if you want the ducted fans to e more efficient pair a smaller lower kv motor with a larger ducted fan. using the largest motor possible spinning a a bajizillian rpm wont do you much good

the real problem is control which you could do with differential thrust but the mixing and gyros will be a nitmare

[PieJesu]

The ducted fans out there weren't designed for lift, but if he ducted his own 3 blade props then I'm sure it'll be fine.

[VTOLicious]

the hornet, would be easyer http://nikon.bungie.org/bwu/images/hornet.jpg

Wrap a depron-suit around THIS and you´ll have a hornet

Michael

[New York Flyer]

Technically you can make one. Either you need to spend a few bucks on a good lipo pack and esc with 40amp and up and some high performance ducted fans, combo servos and make it out of foam.

Or you can use one of those quad copters and just make a pelican fuselage out of foam, which is your only choice for light weight.

I know one guy who did the emperial battle cruiser out of foam and its big and fly's.

[kahloq]

Ok gonna have to disagree with much of what has been said to the thread starter.
First off....ducted fans are far more capable now. I know this as Ive been building my own terminator style 3 fan vtol.

Onelastflight........your Halo craft actually would be really easy to do. And im not joking either. There has already been several successful attempts to make a 4 fan craft fly/hover.
But...by studying your picture, there are a total of 8 thrust points on that bird, not 4.
There are 4 pointing down, and 4 pointing reward. This makes the job real easy.

Here's some numbers for you. If you use littlescreamer jetscreamer 1400 motors in 70mm wemotec fans for the four pointing down...each fan will produce 3 pounds 4oz of thrust on 4cell lipo. i know this as I have an edf thrust stand.
So...with 4 of them, you've got 13 pounds of thrust. It would take an immensely sized depron frame to come even close to that weight.
Now...for the forward movement, the 4 fans units in each pylon that face backwards dont have to be the same size units as they are only providing forward motion as well as turning ability.

Turning would be easy. Left aileron(or rudder) would simply slow the left side forward motion fans 25% while increasing the right side fans 25%. Pretty simple thrust differential. Ive done this on a number of aircraft and it works quite well.

[kahloq]

Pic noting all 8 locations

[VTOLicious]

If you want to build an EDF-VTOL....GO FOR IT! But as RCvert mentioned before, you should consider the following:

THRUST (T) is equal to the product of massflow (m) and velocity (v) T= mv ,while POWER (P) is a funktion of velocity squared P= mv²/2

We can keep THRUST constant by adjusting m and v. Suppose we want to double v. This means we must cut m in half to keep THRUST the same. But if you look at the POWER equation now you´ll see the the increase in v will be squared!!! By doubling v and halfing m we increased POWER required to achieve the same THRUST.

General rule to reduce power required: REDUCE VELOCITY (low pitch/rpm) and INCREASE MASSFLOW (large diameter)

Michael

[onelastflight]

ok thanks everyone for all you're very useful advice, i think i might try the hornet instead. I got 2 little gws outrunners about 85-90 watts each, they use 8x4 props.

Ill do a depron frame and use 2 2s 740mAh lipos for power. Could do it in halves, with one battery through one esc powering one motor, and the same for the other with a receiver connecting them in the middle.

I noticed on that craft which looks like a hornet it apparently had problems with pitch stability. i could extend the cockpit part out the front a bit more with depron and landing skids out the back similarly to give it more pitch stability.

Im gonna have to put this project on the back burner for a while as im currently too busy with exams and whatnot for a scatchbuild. i will keep looking for better ways to do it in the meantime however and ill start when the holidays come round

[Brandano]

You will need something to control pitch, even if you increase the pitch inertia. You either need some control surfaces in the airstream with a sensible distance from the CG or to get the tilting rotors well away from the CG and attempt to control pitch with them. Don't expect "pendulum stability" to work, if you think really hard about it you will see that it doesn't. Probably it's just simpler to add a tail rotor or ducted fan just to control pitch.

[New York Flyer]

Hope the advice worked out for you. And yah... they already have that type of system out there. ducted fans or props.

Check this out

VTOL RC model Ultraman Matjyro ラジコン マットジャイロ (2 min 14 sec)

[kahloq]

That video is quite impressive. Nice and small and it worked great.