A real life flying Sycamore at the Helicopter Museum

[Cyclic Hotline]

I think there may be quite a few people here that might want to make the trip down to Weston next week.

What was it like to fly?

Sycamore to return to Helicopter Museum | Latest Weston-super-Mare and Somerset news - Weston Mercury (http://www.thewestonmercury.co.uk/news/sycamore-at-helicopter-museum-1-5547271)

[sycamore]

` Beyond the fringe,man``...looks like they are using different blades..

[rotorfossil]

They weren’t great. Ground angle markedly different to hover attitude, so large cyclic movement as nosewheel lifted off.. Manual controls with heavy trim springs operated by two trim wheels like a fixed wing. Awkward as you had to let go of collective to operate. Usually lots of stick shake and bounce as difficult to get a good track with the wooden blades. Had to stop the engine for eol practice. Prone to ground resonace on sloping ground landings. Cof G maintained by pumping water between two tanks in front and back by electric pumps. Always marginal on power when close to max weight.
That said, it was after all a first attempt by Bristols at a practical helicopter and it was quite efficient in the cruise.
Sycamore- yes the blades look different to the tapered originals. Perhaps the problem is like the Skeeter blades that the CAA grounded as the integrity of the blades couldn’t be checked without destroying them.

[sycamore]

Maybe they are Belvedere blades,as they were metal,and I think early` Bevels` had wooden blades...

[Jhieminga]

Looking at some images on Google, there appear to be more Sycamores with straight blades. Perhaps a later modification allowed these to be used, they must be cheaper to manufacture as well.

[chopper2004]

I live over there in Salzburg and Upper Austria most of the time so the Flying Bulls Hangar 7 is obligatory visit especially for their excellent Ikarus restaurant! Did I mention free entry unlike IWM Duxford in my old neck of the woods...
My photo of the Flying Bulsl Sycamore on display inside

https://farm2.staticflickr.com/1749/42616830201_14fc35fa98_k.jpg

and undergoing ground running back in Feb

https://farm2.staticflickr.com/1726/27748524497_6f09d2c956_k.jpg

https://farm2.staticflickr.com/1729/41899108924_11f8980520_k.jpg

https://farm2.staticflickr.com/1724/41899106834_9bec4cd89b_k.jpg

cheers

[Jhieminga]

I photographed this one at NELSAM a year ago. Zooming in on the photo it appears to have some sort of balance weight on the end of each rotor tip. The same tips are shown on the photos chopper2004 posted, but on the images on the Flying Bulls page (see here (https://www.flyingbulls.at/en/events-stories/news/bristol-171-sycamore/)) and in the newspaper article, the tips are distinctly different, so they must have switched to a different type of rotorblade at some point. When did you take those photos chopper2004?

https://farm2.staticflickr.com/1731/28749963138_38c5ef3fd6_c.jpg

[heli1]

The Sycamores did indeed have only wooden tapered blades with the bullet tip,weights .
Whilst one aircraft flew with xperimemtal metal blades in the UK Flying Bulls have boxes of new wooden blades from storage .I suspect the picture with squared tip blades is an enhanced PR picture.....Anyway the larest on the Visit to Weston has an ETA of just after midday on 11th Monday,so the museum will open for thst arrival time.

[chopper2004]

I photographed this one at NELSAM a year ago. Zooming in on the photo it appears to have some sort of balance weight on the end of each rotor tip. The same tips are shown on the photos chopper2004 posted, but on the images on the Flying Bulls page (see here (https://www.flyingbulls.at/en/events-stories/news/bristol-171-sycamore/)) and in the newspaper article, the tips are distinctly different, so they must have switched to a different type of rotorblade at some point. When did you take those photos chopper2004?

https://farm2.staticflickr.com/1731/28749963138_38c5ef3fd6_c.jpg (https://flic.kr/p/KNx5pC)

Back in Feb, just before I headed off to Vegas for Heli Expo

cheers

[Cornish Jack]

A proper working one, in the 50s in Khormaksar ...

https://cimg9.ibsrv.net/gimg/www.gmforum.com-vbulletin/835x614/syc01_83b4394740b82f2a4360b54eb913d9ed9cfceecf.jpg

[Fareastdriver]

The best helicopter trainer ever. If you could fly a Sycamore you could fly ANYTHING.

[sycamore]

Very casual there Bill...!

FED,couldn`t agree more..if there was a `hiccup` from Leonides it was `Down(collective),OFF (throttle)..UP to 2( collective pitch )....

[Fareastdriver]

I have posted this before but for those who have not seen it here it is again.

Powered by the Alvis Leonides nine cylinder radial mounted horizontally across the fuselage. The control system was a gimballed rod that went up through the rotor shaft to a spider on top that was connected to the pitch horns on the blades from above. A system later used on the Scout. This gave you two benefits; appalling power margins and limited control authority. It was used as the Royal Air Force’s basic helicopter trainer up to 1965 and as so was a brilliant choice because if you could fly a Sycamore you could fly ANYTHING. The drive system was a centrifugal clutch so when starting the engine one had to be careful not to crash engage the rotor if the engine rpm went over 1,500.

The starting was typical Leonides. Fuel pump on, magnetos on, starter motor switch with one hand, primer switch with the other and throttle with the third. The fourth would be holding the cyclic in case the rotor brake slipped. A failure to start was normally accompanied by a conflagration from the exhaust in which case the drill was to gun the starter motor until either the fire went out or grew in intensity so that everybody, including you, left the immediate area. When it burst into life it was stabilised at about 1,200 rpm to warm up. Whilst this was happening the generator was on line so you could switch on electrical services. This gave you a necessary opportunity to check the fore/aft CofG. As I mentioned before, control authority was somewhat limited. It didn't matter so much laterally but there was insufficient for all circumstances fore and aft. To cater for this there was a hydraulic trimming system; basically a tank of water under the pilot’s seat and a smaller tank in the boom by the pylon. The front tank had a gauge and the contents were adjusted to suit the single /two pilot and/or passengers. Get this wrong and when you lift into the hover you go backwards or forwards quite rapidly.

After this you engage the rotor. On modern helicopters you check the needles and hydraulic pressures as the rotor accelerates. On the Sycamore, no such problem, no hydraulics. It had manual controls with Q feel, i.e. big adjustable springs that had trim wheels, fore & aft and lateral, to enable you to retain control. At flat pitch and IIRC 245 Rrpm you checked the cyclic movement and the trim effect. You also checked the freewheel because if that didn't and the engine stopped you were dead. Once you had set the trim to two notches right and on notch back you lifted into the hover. They had installed a pilot's aid in the Sycamore. It took the form of a cam on the collective linkage that opened the throttle progressively as you raised the collective.

Unfortunately it used to drag and lead quite ferociously. To overcome this and maintain a constant Rrpm one had to close the throttle for the first third of travel and open it for the last bit. The throttle was mounted laterally on the end of the collective pointing inwards to the pilot so it worked in the opposite sense to a motorcycle which caused a multitude of amusing situations.

Once in the hover you adjusted the trim and checked available power. The Leonides as fitted to the Provost T1, my previous experience with it, had a normal take off rating of 2,800 rpm, 4.5 lbs boost/38 in MAP for five minutes and an emergency rating of 3,000 rpm 8 lbs boost/46 ins MAP for two minutes. A Sycamore with two up and full fuel would hover at 2,850 rpm and 42-44 lbs MAP so you didn't do it for long. Should you for various reasons, temperature, altitude, then one could use the previously mentioned 'jump takeoff'. This involved speeding the rotor up tp 275 Rrpm, and then pulling the collective up as high as you could at the same time applying full throttle. The aircraft would 'jump' into the air and when you were airborne you would trickle the aircraft forward so that you acquired transitional lift before the Rrpm died off too much. To give you an idea of how much collective you had available there was a notched plate on the floor with an indicator pin.

Once airborne the incredible efficiency of the Hafner rotor blades in forward flight would show itself. One could sit back, trim out the cyclic so that it flew by itself at 125 knots in perfect comfort. Any other manoeuvre required brute force and an excellent memory because if you wanted to do what you were doing again you noted the control positions because that was where you were going to have to put them. Being a training aircraft in its later days one had to teach and practise engine off landings. Because of the afore mentioned throttle cam the engine had to be shut down because otherwise the cam would rev the engine when cushioning the landing. This gave rise to the following procedure on finals to a suitable landing area, ideally an airfield from an altitude in excess of 1,000 ft. Throttle closed, collective down to the bottom, flare, wait for the rotor to start to overspeed then pull the collective up two notches on the gauge to stabilise Rrpm. Autorotate at 60 kts and accelerate the engine to 1,200 rpm to stabilise and cool it. This is to make sure it starts after landing. After, preferably 30 seconds, shut the engine down. At about 200 ft start flaring off the speed and as soon as it drops to approx. Zero add two more notches of collective. The aircraft will now descend quite rapidly so at about ten feet before entombment pull half the available collective. This will arrest the rate of descent sufficiently to enable the remaining collective to cushion the landing. However:---------- one cannot land vertically because of the design of the undercarriage. This is mounted in such a way that when the weight goes on the wheels they move out sideways. At best this would cause the tyres to roll off the rims and at worst one would dig in and leave the aircraft lurching over with a decaying rotor and no authority. To overcome this, the aircraft is moved forward at the last moment so that it rolls on to the ground.

Then the panic No 1 starts! The droop stops were notoriously unreliable so the engine had to be started before the Rrpm dies away and the blades hit the boom. That being achieved heart conditions advise a return to dispersal and coffee. On shutdown the engine is throttled to idle and above the windscreen is a mirror so that you can see if static droops stops have engaged. When the three rods are vertical then the engine can be shut down. Should one or more not engage then Panic No 2 comes into play. The blades will not clear the boom if the droop stops are not engaged. The mass balance on the end of a blade sticks out forward of the tip and resembles an inert 20 mm. cannon shell. In extreme condition to stop these chopping the pylon off a large leather patch is glued to the boom to encourage them to bounce of. At base we were slightly more sophisticated. To prevent the blades hitting the boom the fire section would come out with a high pressure hose. They would aim a jet of water over the boom/pylon joint from the starboard side so that as the blades slowed and lost lift they would bounce off the water and over the boom.


The RAF stopped using them for training in 1965 after a series of rollovers so they were only used by 32 Sqn at Northolt, day only. I flew one there after a few years on Whirlwinds and I realised that I was ducking at 3 Rrpm all the time. It was because I had forgotten how close the rotor blades missed the cockpit roof by. As I said before, the best training air the Air Force ever had; an experience never to be repeated.

[76fan]

"You also checked the freewheel because if that didn't and the engine stopped you were dead."

Sorry for the thread drift but a little story ..... I had the freewheel re-engage in a Hiller when established in autorotation for a practice EOL with a student in training late on a Friday afternoon. On closing the throttle completely at the standard 600ft (or was it 400 ft?) the ERPM needle rose immediately, grabbed the RRPM needle, and brought it back to about 2400 ERPM (normal RRPM was eqivalent to 3200 ERPM). The rate of descent obviously increased very rapidly but despite opening the throttle I was running out of time as the ground was coming up quickly. As we were intending to do an EOL mindset just before the flare caused me to close the throttle and even cut the engine! That obviously didn't help, nor did the flare do much for the rate of descent and there wasn't much rotor inertia left either. One more Hiller with bent skids and tailboom. Called to the tower no-one believed me ("it's never happened before") when I said the freewheel had re-engaged, however Ray Tandy very kindly came round to my house the next morning with the words "you were right, the freewheel had driven up and re-engaged". Months later the armchair report stated that I should have waited with the engine at full throttle to bring the RRPM back, and then flown away ... Nearly fifty years later I still believe that if I could sit in a simulator knowing that particular emergency was about to happen I still could not do that, that ground came up very quickly ...... Unlike some on these forums I have learnt not to jump in and criticize any accident ... learn from the mistakes of others yes, but unless you were there you probably don't know the full facts ....

[Watson1963]

Fascinating to read your detailed descriptions, FED. I often thought the Sycamore a pretty beauty, but had no idea how much of a handful she was :ooh:.

If I recall right, she was pretty much the first usable SAR helicopter in the UK? Great reading 76fan's notes on the Hiller too.

Nice webpage with Sycamore history:
http://www.heli-archive.ch/en/helicopters/in-depth-articles/bristol-171-sycamore/

[Cornish Jack]

Sycamore ..." Very casual there Bill...! " Just so!! That is the relaxed nature of ignorance! ! :confused: I think that was 1st or 2nd day on shift and the peculiarities of vertical flight were still to be experienced! Still to come were the wisdom of " Don't use the exhaust stub to steady yourself for cabin re-entry" , jump take-off (just) from an up-country wadi, 120 degs in the shade becomes 'Gordon Bennett' Brass Monkey-ish on a 10,000' air test height climb. and when it's 2850/44" to hold a low hover, pulling UP on the practice 'drum' pulls the poor struggling Sycamore DOWN.
"What doesn't kill you etc." :)

[Fareastdriver]

A friend of mine used to be on the El Adem (Libya) SAR detachment. Should they have to pick up a pilot in his dinghy from the Mediterranean the winchman would go down with the hoist and harness up the survivor. They would have a go at lifting them both but if that failed then the survivor would be sent up to sort out himself how to get in the back.

The winchman would sit in his dinghy whilst the Sycamore would fly the survivor to El Adem and then come back for him.

[sycamore]

Naaah,I heard they took a pair of waterskis down,hooked the survivor,then a bit of towing and hit translational lift...away you go...!

[KiwiNedNZ]

I chatted with Blackie who runs the heli ops for Flying Bulls recently when in Raron and he said they are using wooden blades and also using an old guy that still makes the blades. He said he is around 70 years old but still works on their blades.

[Fareastdriver]

Originally the blades were made in sets then balanced and tracked as a set in a large caged tower. It meant that should a single blade be damaged then all three had to be changed.

They could still be tracked; the tarred broom being propped vertically underneath the disc so that it marked the lowest blade was the technique.

I should imagine that Flying Bull used an electronic tracking and balancing system.

[soggyboxers]

https://cimg5.ibsrv.net/gimg/www.gmforum.com-vbulletin/2000x1333/d2f1113e_97b4_4fad_a7b3_28ee06471363_32b207d5166703418f7690b 6e11c8c25309bb19d.jpeg
https://cimg6.ibsrv.net/gimg/www.gmforum.com-vbulletin/2000x1333/518792f2_b8b1_4e78_8139_93268ce16478_f82b1d197ee679e5b2f1abc 8f1d56a372e08627c.jpeg
https://cimg6.ibsrv.net/gimg/www.gmforum.com-vbulletin/2000x1333/3abb51e7_ff40_4532_bd11_a4e13187ae94_e4fedd4eec903a25a009005 84fe56d315e300ca3.jpeg

[THM]

The Sycamore is flying with original wooden blades which have not been modified in any way.

They were sent to a German university to have their integrity checked and were found to be as good as when first manufactured apart from the trim tabs that had started to delaminate.

The Helicopter Museum at Weston super mare had all the original design specifications for the trim tabs and supplied Red Bull with the information and had new ones manufactured and fitted. They currently hold over 50 more main blades so it should be flying for a number of years to come.

KiwiNed: Yes there is an Austrian carpenter who is also available to carryout any repairs.

The current engineer has been working on the Sycamore since it was retired from German military service and he moved to Red Bull when all the airframes and spares were brought from the last Swiss owner.

It flew at the recent RAF Cosford show and then flew to the Helicopter Museum where it is in storage under cover and on public display until July when the aircrew return and it will fly again at the following shows along with the Bo105:
RNAS Yeovilton
Weston Air day
Royal International Air Tattoo
Farnborough Air Show

It may possibly go to Duxford for the flying legends event.

[Fareastdriver]

They currently hold over 50 more main blades

I don't think the RAF ever HAD 50 spare main rotors blades.

[rotorfossil]

I think they came from the German Navy stores. At the end of its service in the RAF, I seem to remember that the problem was that they were running out of tail rotor blades.

[Fareastdriver]

The was a story on PPRuNe about an Australian Sycamore that had an engine failure and force landed in the Queensland bush. The blades were damaged trimming the immediate scenery so a set of blades came up from Adelaide. The roads and track were so rough that the blades were rendered unusable by the time they arrived. No more blades available so it was abandoned.

It is still there in an even bigger state of disrepair then it was then.