Jump to content

Recommended Posts

I was looking at the technical date from the factory web site for these 2 models, can someone explain why there is such difference in the 2 models

 

300C

cruise 86 kn

hover IGE 10,800ft

hover OGE 8600ft

weight

empty 1100 lbs

gross 2050

useful 950 lbs

powerplant

max continuous 190 SHP

fuel

std 30gal

aux 35gal

 

300CBI

cruise 80kn

hover IGE 7000ft

hover OGE 4800ft

weight

empty 1088lbs

gross 1750lbs

useful 662 lbs

powerplant

max continuous 180 SHP

fuel

std 35 gal

aux 30 gal

 

why does the cbi with 5% less HP have 30% less useful load than the C model.

 

this just boggles the mind

::confused::

Share this post


Link to post
Share on other sites

The CBi could lift more than the 1750 gross weight - it is basically the same aircraft as the C except for the engine RPM and FI system. However, with the C model running at 3100 RPM, it does a much better job of pulling out of low RPM - if you loaded the CBi up to an equivalent lb/hp load (around 1940 lbs), it would fly, but you'd have to be really careful not to droop the RPM, as the power curve falls off more rapidly from 2700 RPM than it does from 3100 (3200 is actually red line).

 

The reward for the CBi's 1750 max gross is in the form of much longer times before overhaul on major components:

 

Engine (Lycoming) C: 1500, CBi: 2200 (147%)

Main Rotor Transmission C: 3000, CBi: 4000 (133%)

Tail Rotor Transmission C: 3000 CBi: 4200 (140%)

 

A lot of the life-limited components go about 130% - 140% longer on the CBi also (the main rotor driveshaft being a biggie).

 

The CBi (and the CB before it) is meant as a trainer - with the single fuel tank full, you can fly for 2.3 hours (with reserve) while carrying two 210-lb folks. (Put the same folks in an R22 and you get 1.6 hours with reserve). Of course the 300C will go 4.1 hours with the same two folks...

 

Hope this helps!

Share this post


Link to post
Share on other sites
The CBi (and the CB before it) is meant as a trainer - with the single fuel tank full, you can fly for 2.3 hours (with reserve) while carrying two 210-lb folks. (Put the same folks in an R22 and you get 1.6 hours with reserve). Of course the 300C will go 4.1 hours with the same two folks...

Well, 206, if you put 2two 210lbs people in a 300C,  you MIGHT fly 4.1 hours. If temperature is really nice (80s) - you won't get it off the ground, unless you do a running t/o. And in real life there's usually no taxi way or runway to park on.

 

Just my input...

 

::rotorhead::

Share this post


Link to post
Share on other sites

Yep, 67Nov, that's the gist of it - lower RPM and less power from the engine, less stress on the components due to the lower weight, so longer TBO and life-limits.

 

if you put 2two 210lbs people in a 300C,  you MIGHT fly 4.1 hours. If temperature is really nice (80s) - you won't get it off the ground, unless you do a running t/o.

Well, my 300C experience is limited to a 1977 Hughes 300C and a 2004 Schweizer 300C. Both will easily hover and fly when the temp is 80 degrees - at MGW of 2050 lbs (and if you do the math on full fuel and 420 lbs of passengers you come out at around 2030 lbs depending on equipment). With 2x32 (usable) gal tanks (on the 2004 model), and a 14 GPH fuel burn (common to both of the C models), you get 4.5 hours to fuel starvation.

 

I heard of a guy who was to fly a T&B flight in a dual-tank 300CB and discovered that it had full fuel, the Vibrex installed, and a 220-lb mechanic waiting to go along (shotgun to his 160 lbs of pilotin' physique). The report was that 2,000-lb CB managed to hover at about a 2-foot skid height, but the pilot declined to take it any further into the air. What a difference 10 HP and 400 RPM up the power curve makes... ...so I hear.

Share this post


Link to post
Share on other sites

FW206 - you are oversimplifying.  The CBi and C have different powerplants. The CBi has a HIO-360-G1A (180shp).  The 300C has an HIO-360-D1A (190shp). As far as I know, these are not identical powerplants derated differently.  If what you say is true, then, theoretically and without regards to regulation/certification, I could buy a CBi and operate it to 300C limits, obtain identical performance, but just need to accept shorter TBO's.

 

a94520 - the vintage CB I used for training consistently carried two 210lb'ers with full standard fuel (30gal.) in the FL early summer and never once could not hover, t/o, cruise or land without spare power.  The 300C can carry that and hover OGE (done it consistently) staying within MP limits. But, 4.1 hrs. endurance is a bit of a chuckle.  Even puttering around at max endurance speed (S-L-O-W), I'm lucky to get 3hrs. on 30gal.

Share this post


Link to post
Share on other sites

 ...theoretically and without regards to regulation/certification, I could buy a CBi and operate it to 300C limits, obtain identical performance, but just need to accept shorter TBO's.

 

Even puttering around at max endurance speed (S-L-O-W), I'm lucky to get 3hrs. on 30gal.

From the other side of the upper pulley, the C and CBi are 90% the same aircraft - look at the parts books. Same transmissions, TRDS, MRDS, rotor hub, MR and TR blades, crossbeams, cabin, tailboom. Airframe differences are mostly the oleo struts, the vertical stab, and the cover over the belts.

 

The engine is the same basic HO-360, but they sport different FI systems and more importantly run at different RPM. The C model is rated at 190 HB at 3200 RPM, the CBi gets 180 HP out of 2700 RPM. The upper pully on the CBi is smaller to keep the main rotor turning at the design speed of 471 RPM. If you were to take a CBi and fly it at 3100 RPM, you would be running the main rotor in the 540+ RPM range - lots of lift for sure, but tough on the pitch bearings (anything over 510 calls for an inspection, 540 would be scary indeed).

 

The C model seems more than 10HP stronger because at 3100 RPM (normal cruise RPM), it is sitting above the peak of the engine's torque curve, so if you droop the RPM a bit, there's plenty of torque to deal with it. On the CBi, 2700 is just about the peak, so when you droop the RPM, the torque is dropping off also. You have less reserve, hence the reduced MGW.

 

Did you fly a single-tank C model? Both the C's I fly have dual tanks, one is a 50-gal usable cap, the other is 64 usable. The 50-gal ship will go just over 3 hours plus reserve, the 64 gallons will take you about 4.2 hours. We have a 64-gal CB as well, on the rare times I fly it topped off, it will go 5+ hours with a reserve (longer endurance than I have)!

Share this post


Link to post
Share on other sites
a94520 - the vintage CB I used for training consistently carried two 210lb'ers with full standard fuel (30gal.) in the FL early summer and never once could not hover, t/o, cruise or land without spare power.  The 300C can carry that and hover OGE (done it consistently) staying within MP limits. But, 4.1 hrs. endurance is a bit of a chuckle.  Even puttering around at max endurance speed (S-L-O-W), I'm lucky to get 3hrs. on 30gal.

cross-eyed

 

First, I was referring to 206s statement. He spoke about a S300C with aux tank. That's different from a standard tank.

 

Second, FL is pretty flat. So you talk about a sea-level take off. Not every country is falt like that.

 

I was flying a S300C with two tanks, I was at 180lbs, my passenger about the same.

 

There is no way you get it off the ground with full fuel, 2 180lbs guys, +80s and 1000' elevation. The rpm will decay as soon as you reach hover height. And boy, I don't wanna experience the following landing.

 

Not too speak of a downwind hover taxi.

Share this post


Link to post
Share on other sites

1977 Hughes 300C

BEW = 1270 LBS

Pilot = 240

CFI = 160

50 gal fuel = 300 (32 gal tank and 18 gal aux)

 

Total weight 1970 lbs

 

KFCM - Flying Cloud Airport, 906', Minnesota summer, no problem hovering, flying, autorotations, max-performance takeoffs, steep approaches.

 

2004 Schweizer 300C

BEW = 1310 LBS

Pilot = 190 LBS

CFI = 160 lbs

64 gal fuel = 384 (2 x 32 gal tanks)

 

Total weight 2044 lbs.

KFBL - Faribault Municipal Airport, 960', then see above.

 

The 300C is a tough little air-tractor!

Share this post


Link to post
Share on other sites
1977 Hughes 300C

BEW = 1270 LBS

Pilot = 240

CFI = 160

50 gal fuel = 300 (32 gal tank and 18 gal aux)

 

Total weight 1970 lbs

 

KFCM - Flying Cloud Airport, 906', Minnesota summer, no problem hovering, flying, autorotations, max-performance takeoffs, steep approaches.

In reference to the argument that you could fly 4.1 hours in S300C (1977) with 400lbs people on board, the calculation is flawed:

 

50 gals of fuel won't get you even close to 4.1 hrs!

 

In reference to the S300C 2004 model - it states an endurance of 3.8 hrs - are you cutting edges?

Share this post


Link to post
Share on other sites

Sorry if I wasn't clear - the 1977 Huges 300C has a 49 usable gallon capacity (50 total).

 

The 2004 Schweizer, also a 300C, has 64 usable gallons.

 

Fuel burn is generally 14 GPH (unless you pul MCP, well, continuously).

 

You can safely plan the 1977 C model 3.5 hours to empty (subtract .3 for your 20-min VFR reserve).

 

The 2004 C model will go 4.5 hours to empty (again subtract .3 for reserve).

 

Pretty sure that's what I said earlier.

 

Had a great flight in the older one today, at 15 degrees F and 30.31 in the Kolsmann, there was plenty of power! The new one's for sale (owner bought a Jet Ranger, poor lad), sweet ship if you've got the pocket change...

Share this post


Link to post
Share on other sites

I fly an old 1964 Hughes 269 with a HIO360 B1A rated at 160hp continuous and 180hp max. I am based at 1720'msl and in the summer months see DA's at 3000' to 4000'. I have no problem taking off with full fuel (25 gal) and a  230lb pass plus my 195lb.

 

Remember, engines wear out and as they wear out they gradually become weaker.

 

Just a possible explanation to the anemic 300.

 

Nothing better to hone the skills than an underpowered helicopter!!!!

 

TH55

Share this post


Link to post
Share on other sites
The 2004 C model will go 4.5 hours to empty (again subtract .3 for reserve).

Well, Schweizer states for the 300C model 2004 (on their website) - 3.8 hrs endurance. If your 300C model flies 4.5(!) hrs that would be .7 hrs longer than Schweizer . Too much of a difference to make it sound realistic.

 

And yes, engines do wear out - however, how many pilots fly a brand new 2004 model with a brand new engine? And even if they do, how long will it take for engine performance to decrease?

Share this post


Link to post
Share on other sites

Well, Schweizer states for the 300C model 2004 (on their website) - 3.8 hrs endurance.

Schweizer's website has a few oddities in it.  They use a fuel burn figure of 11.7 gph for calculating operating cost, then they toss out the 3.8 hours endurance figure which would,  if combined with a 64 gallon capacity, mean the 300C burns almost 17 GPH. It actually burns around 14 (an R44 Raven II only burns 15 - 16).

 

Anyway, I just enjoy flying them!

Share this post


Link to post
Share on other sites

67Nov, since I'm no sage when it comes to comparing rpm droop, let me state an obvious difference: the left hand PIC. Also, I've flown all three 300's and the C is by far the more enjoyable, its amazing what a warm feeling you can get from an extra 400 rpms. I've also seen pics of a C slinging a bambi bucket, the most I've ever seen a CBi pull was an old tire for practice.

Share this post


Link to post
Share on other sites

I am feeling fortunate...reading previous comments about fuel burn in the 300C at 14 gph .....What??? My 2003 300C @ 1100 hrs mx Hobbs is consistently getting 10.5 to 11gph. Sometimes 9 gph! Now I operate at 21 to 23 inches MP at sea level up to 3000 feet MSL and baby the baby...keep everything well lubed...25 hr oil changes and main rotor every third flight.....perhaps that helps!

Share this post


Link to post
Share on other sites

Welcome George and its fun to read these old threads. Yes, if you are flying around light and not pulling alot of power 10 gph is typical in the 300C. Flight training with two on board and alot of hovering maneuvers we plan for 12 gph but it is usually slightly less.

When I am crop dusting in the 300 it is more like 14-15.

Good idea on extra lube for the rotor head... those dang flapping bearings wear too often. Also I really liked that the military put zerks on the droop stop ring allowing extra lube there more often as i've seen a fair ammount of pitting on the components from lack of lube and moisture contamination.

 

The 300C is a great little workhorse. I have lifted 780 lbs on the hook or 75 gallons spray in the tanks on numerous occasions. The one we use for that is very basic and has an empty weight of 1106 lbs.

  • Like 1

Share this post


Link to post
Share on other sites

Hi all, my first post here. Been doing some reading through different forums lately and this thread made me feel as though I should share my experiences here if anyone is interested still in the 300cbi's performance compared to the 300c.

I have flown both on ag. Thats right a cbi on ag. I bought this ship brand new. Strapped tanks to it and a hook and went to work. Other than having some major bearing falures in the first 200 hours it done 2000 hours of absolute trouble free flying. Other then routine maintanence it did not cost a cent. That aside the 300C's i have flown havent been as reliable.

As previously mentioned the hp rating of the two 300s are basically the same the major difference is the torque! This is what makes helicopters fly not hp.

The 300cbi certainly is massively power limited compared to its sibling the C, but it can still haul a decent load, what these aircraft can do with just 100rpm up yoursleve will leave you breathless... I enjoyed every hour of flying in the cbi. It made you learn real fast and stick to the rules of engagement for keeping focused and 100% concetrated on the task at hand. The boundrys could be exploited like turning down wind with a load on but it quickly reminded you that your being silly and dont do that again. The safety margin for this kind of flying was huge once you got use to it. There really is nothing like a 300. One point i would like to make to a previous post is, apiaguy how on earth can you stick 75 gallons into a 300c? Thats 300 litres in my language.. Best we could do was about 250 legal litres. Either your using a runway or your running a c20b as it cant stack up. Anyways I sold my 300 after 8 years of very enjoyable flying and bought a r44ll.Its certainly not a 300.

  • Like 2

Share this post


Link to post
Share on other sites

Well I don't like old threads much, Flingwing206 RIP!

My thoughts exactly!

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

×
×
  • Create New...