Hurricane 550 speed, level fligth

[Phoinix]

I was just wondering, did any of you measuring freak guys ever record the speed of hurricane in level flight?

I have mine set up with 550 CF blades, Z30 @ 1630 RPM HS, 2600g TOW and i got 130km/h in level flight, full collective. Not something to write home about, but that is quite some speed. I'll try to do some more work, trying different blades and HS's.

[woz]

There are a couple of us here and have always wanted to test the speed !
Did you attache a gps module to the heli ?

Must have been fun !

[Phoinix]

GPS? :D No, i'm more of an old fashioned guy. I had pitostatic system from eagle tree. I couldn't belive the readings until i sat in the car and drove to test the measuring. It was about +/-3km/h, which is very accurate considering it wasn't a standard day (15°C, 0m above MSL,...)

http://i97.photobucket.com/albums/l236/BlenderPilot/Show%20and%20tell/Modeli/Hurricane%20550%20Build/hurricanespeed2.jpg


I still have some problems controling very high collective for level flight (as it can be seen from the up's and down's in airspeed reading).

Next step to go, is to try and make my own vane pito tube, that will adjust itself into the airflow (more accurate readings).

[Zoobie]

I mounted my GPS and the best I could get was 55km/h. I am using a Z20 with CF blades. How long was your "run-up"? Your speed sounds more like I would have expected.

[skydude]

Good project. Do you think there might be any problems with rotor wash affecting readings? Would pitots (Are there two, one into the airsteam and one across) on a boom out front be more accurate?

I know just enough about it to ask stupid questions.

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[Phoinix]

55km/h is very low top speed for such helicopter. Did you give full collective? My setting is full collective = +10°.

I had a run from about 600m towards me and continued for more than 700m. I got to 100km/h in 12 seconds. It is very diffucult to master all the lift of full collective into speed but practice makes perfect.


Good project. Do you think there might be any problems with rotor wash affecting readings? Would pitots (Are there two, one into the airsteam and one across) on a boom out front be more accurate?


Rotor downwash has little effect on top speed readings but it has some during hovering and translation into fwd flight (mostly disturbance in reading). During translational flight there is very little downwash as the ram air is directed through the rotor disc.

Pito tube out front would make it more accurate, that is right. Pito tube uses the difference of ram air and static pressure (like you said, one in the air stream and one accross - no ram air). You also have to take into account the tilt of pito tube (eagle tree atleast). I tilted it about 25-30°upwards so it aligns with the air straem when helicopter is in flight (nose down attitude). Error for disregarding this is around 30km/h less during 120km/h level flight. Measured in a car. About 5-7° tilt error is tolerated with no error in measuring airspeed.



http://i97.photobucket.com/albums/l236/BlenderPilot/Show%20and%20tell/Modeli/TLH/2-5translacija.jpg

http://i97.photobucket.com/albums/l236/BlenderPilot/Show%20and%20tell/Modeli/TLH/5-8translacija.jpg

http://i97.photobucket.com/albums/l236/BlenderPilot/Show%20and%20tell/Modeli/TLH/nad10translacija.jpg

[Zoobie]

I see two problems with my technique: I dont have enough run-up, I need to practice too increase my speed and keep the heli level., the heli wants to ascend as you move into FFF.

BTW, I have heard of Trex 450s going at 80km/h on a radar - thats why I was surprised at the low speed I recorded.

Back to the drawing board!!

[Phoinix]

Be careful going full collective. Helicopter will get somewhat touchy in fore and aft cyclic. I managet to get into PIO (pilot induced oscillation) on my third run. Avoid flying over yourself at all costs and remain at safe altitude when trying. 100ft altitude will be gone in a blink of an eye with both of the problems encountered.

[skydude]

Good job! Great sketches. Yeah. if you can get the pitots calibrated it should be very accurate. Do not need to compensate for estimated angle error of using radar gun for example. This would only be precisely accurate if you were to fly six feet high straight at the gun holder.

Sounds like a hoot.

Completely relax. PIO's have almost done me in hang gliding. My first high speed flight in a high performance glider was an eye-opener. You gotta force perfect smoothness. You might enjoy using long tx sticks. They have the advantage over expo of being able to adust the control ratio while flying. I think mine are called 'Gorilla Sticks'.

How much does the onboard equipment weigh?

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[skydude]

130 km/hr = 78 mph. That seems wicked fast.

There has been a lot of controversy on these sites regarding actual true top airspeed of various helis.

One of the latest 'reliable' (not sure what I mean by that) figures was 55 mph for a rex 600.

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[ukgroucho]

Nice work Phoinix.

I've been thinking about doing this myself but have not gotten around to attaching my air speed instrumentation (Eagletree also) to my 550.
I have used it on my 40" wing and got ~105 mph (say 168 kmh) in a dive.
130 kmh seems very respectible for a helicopter.

Skydude. The Eagletree pitot attachment is VERY light. I weighed mine and it came in at 4.5 grams.
This will vary depending on how you set it up. You attach a flexible pipe to the pitot measurement sensor (with a bit of hard pipe at the end to prevent measurement variations) to enable you to place the measurement 'input' where it makes sense but without having to place the actual pitot and board somewhere exposed. I only have a short length of flexible pipe attached - obviously longer pipe = more weight but you'd still struggle to push it up to more than half an ounce even if you used all the pipe that they provide with the sensor.

[xodarap1]

I don't have the high speed toys to accurately clock the speed runs with these heli's but they are wicked fast! My best guess (from flying parallel to cars on the highway in the 70mph zone behind my flying field) that 70 or 80mph sounds easily possible for a Z30 powered H550, with 50 or 60mph for a Z20 powered H550. My flying field is as large as a football field and even the Z20 powered birds can cover that distance very rapidly. Hmm...I wonder if I could convince my friend at the sheriffs department to clock me with a radar gun. :) Of course if anyone had a closed course, pilot could sit in passenger seat and fly heli flat out in front of car heheheh :shock: :YeaBaby: ;) Another option would be to take it to a drag strip and have em time it covering the 1/4 mile past the guns.

[skydude]

Yeah, tracking automobiles should certainly give a good rough order of magnitude. You know most people are not going 'under' the speed limit.

Damn, that is fast. I would have never guessed. As I mentioned, all the threads I have read have these things going quite a bit slower.

And light weight equipment. Now you guys have me wanting to get in on this. Sheesh. Just what I need. Another obsession.

Yee Haw

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[skydude]

Hmm...I wonder if I could convince my friend at the sheriffs department to clock me with a radar gun. :)


If you get this going make sure you compensate for angle to the line of flight. And wind.

[worldofmaya]

Hi!
Those number sound good. I tried it the same way... my flight field is nearby a stree with cars going up to 100km/h... no chance for them. Another thing that is pretty nice is acceleration. As long as your opponent doesn't sit in a dragster :)
-klaus

[skydude]

Hi!
cars going up to 100km/h... no chance for them. :)
-klaus


Spankin the traffic. Sounds like a hoot.

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[concept1]

the world speed record for a electric heli is around 78mph, but with that said it is very easy to exceed that speed. for the record you must maintain level flight and make 2 passes, through 2 gates (I forget the distance and run up they give) but one up wind and one down wind and you take the average. One of my flying buddies broke the speed record in 1995, but it was broke again in 96 or 97 by a russian. his 95 machine had been clocked at well over 100mph but the day he made his run the weather wasn't the best. It won't be long before he takes another go at it, I hope this spring! for the record it is almost more about following the specs but I will say his machine is wicked fast!!! my Hurri is no where even close, so to get the Hurri in the upper 70's you are getting some "down hill" help, in a dive it would be easy to hit 80+

[xodarap1]

so to get the Hurri in the upper 70's you are getting some "down hill" helpThat makes a lot of sense concept1. Most of my faster speed runs have been after coming out of a loop on the back of the field, past me, then up into a high bank left turn, then down to flat again out along the highway/traffic.

I have been amazed that retreating blade stall hasn't been a problem as it would be on a full size heli.

All I know is that when the heli comes past me, flat out, flying flat after coming down out of a large loop, it's cookin' man! :-) The sound is neat and it wouldn't be a good time to lose focus heheh. :)

[concept1]

yea if you search for the world speed records, you will find the requirements for speed to qualify, and many of us would never be able to do it. I mean keep the heli that level at full pitch for the distance needed! it isn't like a car you just drive straight and their is your top speed. try to keep your heli going straight and level. it is fun though to let her go full out, I like the stall turns to a big high dive and full speed down the field then it's easy to hit probalby close to 80. I had my raptor 50 clocked once years ago by a buddy who was a cop, I was utterly shocked and dissapointed at how fast or acctually "slow" it went. never did it again since i'd rather assume I am going 80 then know I am only going way way less in level flight!!!! I don't think I got near 80 even in a dive with my old 50 running 1900 head speed. but with the electrics running 2400rpm it would be much easier.

[Phoinix]

I have been amazed that retreating blade stall hasn't been a problem as it would be on a full size heli.


Real 1:1 scale helis experience retreating blade stall as the blades spin at much faster rate than on the model helicopter. This is due to higher rotor span. The tip of the blade is somewhere in the vicinity of 90-95% speed of sound. My hurricane's tip speed is around 102m/s @1630 RPM. About 3 times less than 1:1 scale heli. You won't see any effect of retreating blade stall at those tip speeds.