Flying Project

[Aerometalworker]

Nick,
Looks interesting so far, I have a feeling its a bit under designed however. I have some drawings of the DH-4 "helivector" and some notes on the development of it. The rotor head is much more complex and robust then your design, and the chain drive might not be a good idea due to driveline harmonics. Belt drive would act as a sort of dampener. The DH-4 was one of the few personal helicopters that actually flew, and it was powered by one of our MK 55 engines of about 50 horse 100% duty cycle.
-Aaron

[turbo38t]

What about the 100cc Yamaha motors used for goart racing. They gotta be upwards of 50 hp. Dave

Just about anything related with flying is expensive. The prices I've seen for
some gyros that are small and simple still bring a big price. Same with ultralites. Of course the motors and props are a big part of the bill. Gyro
rotors are expensive. Rotors like that I wouldn't attempt to build. Smaller rotors and props can be home built.
This unit I want to build shouldn't be too expensive. The engine will be the
biggest expense.
I need a two stroke 30-35 hp range........strong but lightweight. ANYONE
HAVE AN IDEA WHERE TO FIND AN ENGINE LIKE THIS? Also what size engine in CC equates to this hp . I'm thinking maybe off a dirt bike or the like. I hate to pay for an entire bike just for the engine. Any leads welcome.
Nick

[monte55]

Nick,
Looks interesting so far, I have a feeling its a bit under designed however. I have some drawings of the DH-4 "helivector" and some notes on the development of it. The rotor head is much more complex and robust then your design, and the chain drive might not be a good idea due to driveline harmonics. Belt drive would act as a sort of dampener. The DH-4 was one of the few personal helicopters that actually flew, and it was powered by one of our MK 55 engines of about 50 horse 100% duty cycle.
-Aaron

Have you looked at the first post of this thread with youtube video links? It is chain drive, 30 hp 2 stroke water cooled kart engine and fixed pitch ultralite blades for the rotors. I agree a cogged drive belt probably would be better.
I am using what I have easy access to and am in the prototype stage and testing needs to be done. All constructive input welcome here. It's a fun project. Do you have any links to the DH-4 ?....Nick

[DrBob]

Well I don't know what you googled Turboglen but there is a big difference between a pulse jet and a ramjet. The pulse jet is what the German V1 'buzzbombs" used. There is a valve arrangement at the air intake which rapidly meters air and fuel into the combustion chamber. There used to be a hobby version of this which I remember made a heck of a racket and almost always got so hot that it wound up setting the model plane it was mounted to on fire!

A Ramjet is simplicity itself. A tube with an open front and a means of metering in a spray of fuel. An igniter. That's all. The advantage is very light weight, very good thrust and no theoretical maximum speed. The faster it goes the more thrust. The problem is how to start the darn thing. You have to get a volume of air moving through it before you can feed in fuel and light it off. The USAF is currently researching a supersonic version - the SCRAMJET.

On the Hiller Hornet, there were two ramjets mounted to the tips of the rotor blades. As I recall the rotor disk was about 25'. The only tricky part was the rotating seal that connected the fuel line from the tank to the lines running down the rotor blades. To start up the Hornet, you turned a crank by hand (fancier version had electric start). When you had it going good you hit the ignition button and kept cranking until the jets fired. when you had operating speed pulled up on the collective and off you went! It had the usual collective lever but the cyclic was a simple yoke that directly moved the swashplate. The rudder pedals moved an angled fin on the tail. No tail fan was needed as there is only slight counterforce with the ramjets. I was fascinated by this machine when I first saw it in Popular Mechanics magazine in the 1950s and was always disappointed that it never caught on.
Later when I started flying (Cesna 150s and 180s) I kind of forgot about the Hornet but recently I have been hoping to run across one. Maybe even fly it someday DrBob

[MR.57]

......
I need a two stroke 30-35 hp range........strong but lightweight. ANYONE
HAVE AN IDEA WHERE TO FIND AN ENGINE LIKE THIS? Also what size engine in CC equates to this hp . I'm thinking maybe off a dirt bike or the like.

You can easily get 35+ HP out of a modern 250. The main problem with using a motocross bike sourced 2 stroke is that unless you machine your own crankcase or find some pre-1970's vintage oddball it's going to have an integral 5 or 6 speed transmission. You can't shift a helicopter transmission in midair, so those extra gears are wasted weight in your application and do nothing but add an unnecessary point for potential failure.

Jet-ski engines don't have an integrated transmissions, but they are almost all liquid cooled. Liquid cooled = more weight.

A chainsaw engine would fit the bill, but you'd need at least 4 or 5 "hot rodded" chainsaw engines to come close to making 30 HP. It's a plausible, albeit ridiculously overcomplicated solution to use multiple engines.

An air cooled snowmobile or better yet an ultralight aircraft engine would be ideal.

Rotax 447 meets/exceeds your specs. 40HP, air cooled 2 stroke twin weighs about 60 lbs and is available with several different ratio reduction gearboxes. http://www.rotaxservice.com/rotax_en...otax_447UL.htm (I am not affiliated with the seller in any way. Link is provided for reference purposes only - notice prices are in $Cad) With a little searching you can find a used 447 for under $1000, so they aren't prohibitively expensive.

The motorcycle chain drive doesn't seem like a good idea to me, I'd use a reduction drive intended for aircraft duty. Either a Gilmer belt drive or a gear reduction box. Again it's more expensive, but what's your life worth to you?

My main concern about your project is that it appears nothing has been safety wired or drilled for the provision of safety wire/ cotter pins. One loose bolt on an aircraft can kill you even if you're still on the ground. Safety wiring or positive locking devices (such as cotter pins or locking clips) should be considered *mandatory* on all aircraft structural hardware unless you have a death wish.

[monte55]

It is in the mock up stage now. All fasteners will be properly secured. Thanks for the input.................Nick

[bear]

This is the coolest project. Good luck.

[nocheepgas]

Been a while since you posted any updates, how's things progressing? Looks like a very cool project.

[monte55]

Haven't done a lot lately. I've been busy trying to make a dollar. I have been taking things apart to loctite, drill and secure etc and that's time consuming. I'm very close to doing an engine runup with the head but without rotors very soon. Next is to make rotor blades and I'll almost be done. Then ground testing is in order.

[turboglenn]

You think when you're finished that if i coevr your gas you coudl fly up here and help me with my homemade CNC plasma table??? LOL LOL

Glad to see that you've not given up on this either way, I can't wait until the day I actually see a video on youtube of "monte55 flies his home made heli" LOL

keep it up and show us what ya got!!