RC India

has anybody trying this style

http://onlygizmos.com/humminger-3-0-shows-off-its-potential-at-technovanza-video/2010/02/ (http://onlygizmos.com/humminger-3-0-shows-off-its-potential-at-technovanza-video/2010/02/)

that is a really good model
is there someone with a better one?

As u said a really good model, if only it could fly too.

Wow ! What an opportunity to discuss about the design aspects of (RC) planes ! :o

So after watching the video in the link above, WHY did the plane not fly well ?  Not enough wing area ?  Not enough airfoil ?  Or just not enough thrust ? :headscratch:

1. Tail heavy plane.
2. If you dont have a dihedral, you definitely need ailerons, this one has none.

honest opinion, is not much attention paid to wing loading, directional stability, like 'SunLikeStar' brought out tail hvy. Small fin large moment arm, that's how it spiraled (Called 'Spiral Instability' in Test Flying parlance).
A pusher tractor concept has other major complications, like fuselage twist due to asymmetric gyroscopic ( a property of gyroscope called Precision) effect etc. erratic pitch due to two thrust lines sandwiching drag line etc. As a tech demo in a a tech institute is fine, eventually they will have to shelve it.

I hope i am wrong. :thumbsup:

You are absolutely right. as i said in my earlier reply with pun intended.

I think my post has generated some interest  :headscratch:
 as i saw humminger looks like   :banghead:
but blackbird is much better  http://www.youtube.com/watch?v=v18FY4oHc3Q (http://www.youtube.com/watch?v=v18FY4oHc3Q)

i loved the concept dunno about it's drawbacks

Is there someone who would stand up and create a reall good and better model .   (:|~

 :salute: and contact DRDO for more funding since i think they are being generous here  {:)}   :giggle:   :bow:

AFAIK, we the RC people of India enjoy our beloved hobby and we keep doing all sort of fun things including model making but I dont think (IMHO) anyone is interested to work with or for DRDO or any other such GENEROUS agencies to spoil our fun. I know of one such forum where people are money oriented. Kindly try and post there and i am sure you will get good response. Thx

@ crazypilot :  i won't say more than [ ;D   :giggle: :giggle: :giggle: :giggle: :giggle: :giggle:]

you couldn't catch sarcasm in my comment  :giggle:  i  never will work for drdo though!!

i never expected this

 http://www.google.com/images?um=1&hl=en&biw=1349&bih=555&tbs=isch%3A1&sa=1&q=vertical+landing&btnG=Search&aq=f&aqi=&aql=&oq= (http://www.google.com/images?um=1&hl=en&biw=1349&bih=555&tbs=isch%3A1&sa=1&q=vertical+landing&btnG=Search&aq=f&aqi=&aql=&oq=)
 ;D
but am asking if someone is trying to make a scaled down version of this

cut the tail replace it with a stand and whatever you cut of replace it above the plane towards the rear [for skymaster] ?
wild imagination though...   :giggle:

Hi Guys,

This is Rishikesh Karande here..happy to see that the plane I designed is generating so much interest ! :)
I think I can clear out a few questions asked above..

Firstly..the plane did not crash due to small wing area, or bad airfoil or low thrust. Neither did it crash due to being tail heavy(I have to agree it was TOO tail heavy..you can see that from the wing placement) or due to absence of ailerons. Neither due to directional instability. (There was a lot of fuse twist as we expected..but we made a strong structure of CF Spaceframe to counter that..and it worked :). Not much attention was given to erratic pitch..sadly..)

The only reason it crashed was due to BAD PILOTING..BY ME! I actually gave the aileron input to the transmitter by mistake when I was supposed to apply the rudder... :(. That is why you can see it roll to the right at the end. I am still learning how to fly and that..was my 5th flight..so..screwed it up.

Anyways..it is a very efficient concept for VTOL. The main reason we went ahead with counter rotating power system is to cancel out the torque of the motor..because the elevon area available was insufficient for roll stability during hover. And also..the thrust to weight ratio was 1.3 with payload..without payload, it was 1.7..so thrust was no issue at all.

Any more questions about the design..I hope I can answer..
and yes..my juniors are still working on that concept..and I'm on to find a better one  :)

Thanks a lot for the interest shown,
Regards,
Rishikesh

Mr Rishikesh Karande
post some more details, in terms weight, wing area, cg margin, cg in terms of MAC, type of Aerofoil, and other relevant data you find deemed fit posting, let us run some math for you. (If you wish to, that is).
1.  how do you think only a pusher or a tractor is canceling the reactionary torque ?

2. if pusher-tractor is efficient why is it not being used in real life aircraft ? think about it.

I am reminded of William Shakespeare's , “As it fell upon a day” , how to recognize  a Faithful friend from a flattering foe, constructive criticism is for you to improve, if you want to that is.

like I said, I hope you are right and I am wrong :thumbsup:

The AUW was 1.2 Kgs..and as for the other specs..I really am not very comfortable posting it here. I hope my wishes are respected.

1. A pusher or tractor does not completely cancel the reaction torque..but it surely reduced the amount of elevon deflection I had to give for roll stability.

2. And I have to agree that push-pull config is not necessarily the most efficient one. The fuse twist is just tremendous..the weight of the fuse shot up drastically to resist the twist..also, we could not look into the aerodynamic aspects..cannot comment. But I can definitely say that the rear prop is not working at its maximum efficiency due to contaminated air at its leading edge. So the thrust is not necessarily twice for same motor-prop combo.

When I said the design is efficient, I was not referring to the power system..I was actually referring to the way the design accomplished the problem statement of the competition. Sorry I did not make that clear.

Also, the main reason we went ahead with push-pull is because we did not have funds to get a contra-rotating motor-prop assembly :(. Else, that was the first preference..

And BTW..constructive criticism is always welcome :) I would love to find more issues with the design..apart from structural weight, bluff front, huge elevator area, small moment arm, tail heaviness, fuse twist, roll stability, or any similar aspects..

I'm just stating my experience working with that model..I am sure that if a good and experienced pilot were flying it, it would not have crashed..I mean, any well designed aircraft will crash if the pilot doesnt know how to fly..thats what happened when I was at the controls.. :(

i agree, thats why designers don't fly. it is the test guys who do the flying part, if you have put your heart and soul and a lot of time into a project. i would love to fly it for you. before that we will go over the design and thrash out design issues etc. anytime gimme a holler

@augustinev

i wont agree with that completely for me it's straight opp.  :P

@rishi :  why not replace those hex stands by a cone and you could have done some sanding on to the plane  :thumbsup:

i think decreasing overall length would have helped
i am no pro but would like to here from some about those sugg. by me!  :bow:

@Augustinev: Wish I could..would love to see my models flying with good piloting. But I dont stay at Thane currently..pursuing masters at Kanpur..will let u know when I do make another one there  :)

@cvjoy: The cone thingy is pretty cool  :) will surely reduce drag....we were gonna try that out..but had to make those stands a few hours before testing..so went ahead with whatever works :P. Esp when we have a T/W>1.5 we decided to give time the higher priority..

I'm not a pro either..but here is what I would say..
Decreasing the length would have helped reduce the structural torsion..but it would have further reduced the small tail moment arm I had..because there was a minimum fuse length fixed by payload..the remaining length was for my tail moment. So any deletions would have happened from there.

my suggestion drop the tail motor, crank the fin and motor mount to counter the torque, increase the prop size if the motor can take it. or else put a bigger motor,
me, presently posted near calcutta

@ rishi : welcome to RC india forum   nobody seems to have welcomed you  :giggle: :giggle: :giggle: :giggle:

Why not attempt  Image no 1 or 4

@Augustinev: Dropping the tail motor is quite obvious..I would like to know what exactly do you mean by "cranking" the mount and fin..
Will let u know when I make one here :)

@cvjoy: Thanks a lot :)
I thought about the design in image 1 before making humminger. The major flaw we found was that the mechanism to rotate the fan involves extra weight, extra bearings for the shaft, extra actuator and will need more space. All this will lead to an extra component which can fail..so it was out.
And as far as image 4 is concerned, it cannot sit on its tail. To make it do that, I would have to make two(or atleast one) extra support leg which would have to go over the rear prop to the tail. That takes a lot of space and also makes the boom a bit structurally weak. But yet, I have been thinking about that for a while now..because the structure can still be made a bit more stronger by good materials. Would love to give it a try actually  (:|~. Just have to make an elevon and try to get the tail along the fuselage reference line..should work! ;D

The major problem we faced was stabilizing the aircraft when it was vertical..as in in hover mode. We had just started learning about IMU's and could gather angular data. Had a few challenges while giving control signals to the sevos though..did not implement that in the final aircraft due to time constraints. So even if we make something like image 4, we still need either a very very good pilot, or a good control system for hover..

Why not duct the tail motor and spread tubing to those legs so that you can have more control on how you fly
though it will take space and become heavy you could always  be sure of greater control with 4 nozzles on the tail end.
Greater stability can be acheived .
though at the cost of speed though.

one more tip
make 3 stands in stead of four . and at 120 deg.  i think same stability during flight can be achieved (nvr tried but i still doubt it's stability when it sits it the plane is long enough then it might tip over.)