Google Groups no longer supports new Usenet posts or subscriptions. Historical content remains viewable.
Dismiss
Ventus bT/cT comparison
3,426 views
Skip to first unread message
Jim Pengelly
Apr 17, 2012, 8:46:24 AM4/17/12
to
Hi everyone,
I fly a Discus bT at the moment and absolutely love it. However, I
am thinking of upgrading to a flapped turbo in the next one or two
seasons and the Ventus bT/cT would seem to be the natural
choice.
I have heard conflicting opinions about the various models:
i) The bT has handling issues and the cT was designed to
overcome these issues, with a bigger rudder and some other
changes. The cT is the model to go for.
ii) The cT has handling issues, can be difficult to bleed approach
energy due to the brake configuration and was not a popular
model, which is why there are so few of them around. The bT is
the model to go for.
iii) The bT and cT perform relatively poorly in 15m mode rather
than their 16.6m (bT) and 17.6m (cT) modes, so competing in
15m mode is not recommended.
Any thoughts much appreciated.
Cheers,
Jim
I fly a Discus bT at the moment and absolutely love it. However, I
am thinking of upgrading to a flapped turbo in the next one or two
seasons and the Ventus bT/cT would seem to be the natural
choice.
I have heard conflicting opinions about the various models:
i) The bT has handling issues and the cT was designed to
overcome these issues, with a bigger rudder and some other
changes. The cT is the model to go for.
ii) The cT has handling issues, can be difficult to bleed approach
energy due to the brake configuration and was not a popular
model, which is why there are so few of them around. The bT is
the model to go for.
iii) The bT and cT perform relatively poorly in 15m mode rather
than their 16.6m (bT) and 17.6m (cT) modes, so competing in
15m mode is not recommended.
Any thoughts much appreciated.
Cheers,
Jim
Peter F
Apr 17, 2012, 10:26:25 AM4/17/12
to
Can't speak for the turbo versions, but for the pure glider option the
problem with the Ventus B in 16.6 mode was that you couldn't carry enough
water to get it going even here in the UK.
(Not sure how much water the Turbo versions can carry - do they have same
reduced all up weight as Discus T)
The long wings on both B & C are great for weak wave and long glides at the
end of the day. The Turbo will let you motor into the stronger wave & get
you home at the end of the day in 15m mode
Winglets improved any handling "issues" with Ventus B
Best option is to fly in 15m mode with winglets
Both Ventus B & C are less forgiving around the stall than your Discus so
you probably need to be more cautious when picking fields / starting the
engine.
The reason there are fewer Ventus Cs around is mainly 'cos the LS6 came
along and then the V2.
All depends on what you're flying against. You're unlikely to outrun an LS6
or V2, in absolute terms & if you're flying handicapped comps then stick
with the Discus!!
PF
problem with the Ventus B in 16.6 mode was that you couldn't carry enough
water to get it going even here in the UK.
(Not sure how much water the Turbo versions can carry - do they have same
reduced all up weight as Discus T)
The long wings on both B & C are great for weak wave and long glides at the
end of the day. The Turbo will let you motor into the stronger wave & get
you home at the end of the day in 15m mode
Winglets improved any handling "issues" with Ventus B
Best option is to fly in 15m mode with winglets
Both Ventus B & C are less forgiving around the stall than your Discus so
you probably need to be more cautious when picking fields / starting the
engine.
The reason there are fewer Ventus Cs around is mainly 'cos the LS6 came
along and then the V2.
All depends on what you're flying against. You're unlikely to outrun an LS6
or V2, in absolute terms & if you're flying handicapped comps then stick
with the Discus!!
PF
John Ferguson
Apr 17, 2012, 2:02:59 PM4/17/12
to
I'd say i) is the most correct of the statements listed. The cT with
landing flap and full brake comes down rather steeply, just point at the
ground ... not recommending that though.
The cT does have the restricted 425 KG max mass when the turbo is
installed, as does the bT. With the engine removed the max weight goes back
up to 500kg, find one with a carbon fuselage if possible, saves 10 kg on
the weight plan.
I'm on my second cT now, great performance in 17.6, probably the best value
L/D you can buy.
In 15m mode with turbo installed the wing loading could be described as
high, but if you live in a country with big thermals that's not a worry.
Somehow it likes landing at 60ish knots rather than the yellow triangle
speed.
Try one if you can get a flight.
landing flap and full brake comes down rather steeply, just point at the
ground ... not recommending that though.
The cT does have the restricted 425 KG max mass when the turbo is
installed, as does the bT. With the engine removed the max weight goes back
up to 500kg, find one with a carbon fuselage if possible, saves 10 kg on
the weight plan.
I'm on my second cT now, great performance in 17.6, probably the best value
L/D you can buy.
In 15m mode with turbo installed the wing loading could be described as
high, but if you live in a country with big thermals that's not a worry.
Somehow it likes landing at 60ish knots rather than the yellow triangle
speed.
Try one if you can get a flight.
StaPo
Apr 17, 2012, 2:43:54 PM4/17/12
to
Dne úterý, 17. dubna 2012 16:26:25 UTC+2 Peter F napsal(a):
.
.
.... The reason there are fewer Ventus Cs around is mainly 'cos the LS6 came along and then the V2...
.
.
Actually, the ratio of manufactured Ventus C's versus B's is about 50/50,
with even slight favor to C's, see http://rcawsey.co.uk/shirth.html
.
.
.... The reason there are fewer Ventus Cs around is mainly 'cos the LS6 came along and then the V2...
.
.
Actually, the ratio of manufactured Ventus C's versus B's is about 50/50,
with even slight favor to C's, see http://rcawsey.co.uk/shirth.html
Bob Gibbons
Apr 17, 2012, 11:36:23 PM4/17/12
to
about 1500 hrs on the ship over the past 13 years.
-- One possible reason for the apparently small number of C models in
the US is that at least the early C's were brought into the US as B
models, and then re-placarded as a C model. My '87 cT has the original
B placard still in place, but X'd out with the new C placard mounted
below it. I notice that a number of Ventus B models in the FAA
database are in fact C models whose owners never updated the FAA
records.
-- I've got no complaints regarding the handling of the Ventus C,
thought I fly almost exclusively with the 17.6m tips. I've noticed no
issues with handling with the 15m winglets, however.
-- Unfortunately I have never had to opportunity to fly a Ventus B.
The only unbiased comment I can quote is from Derek Piggott in the Dec
1992 / Jan 1993 Sailplane & Gliding issue.
"Whereas the earlier model has rather a reputation for stalling and
spinning if flown carelessly. the C model seemed a model of docility.
I frequently pulled into steep thermalling turns, getting down to well
below 40kt with only an obvious buffeting and sinking feeling clearly
indicating that this was far too slow. It did not once drop a wing
requiring any proper stall recovery. In spite of the extra wing span,
the rate of roll is excellent at all speeds and it is easy to fly
accurately rolling into and out of turns"
-- Max gross with or without the engine is 500kg. The issue with the
engine in place is the 255kg non-lifting limit. With the engine in
place, the pilot weight determines whether the max gross of 500kg or
the non-lifting limit of 255kg kicks in first. For my weight and 28
gal of water, I hit max gross just before I hit the non-lifting limit.
Bottom line, with the engine in place and ballasted to max gross, you
are at the same loading as without the engine, but you cannot dump
down to the same low loading as without the engine. With the engine
in, I can go from 10.1 lbs/ft2 max down to 7.9 lbs/ft2 min. Without
the engine, W/L ranges from the same 10.1 lbs/ft2 down to 7.2 lbs/ft2
(all with 17.6m span). The B model has the same issue and limitations.
-- For what its worth, only the C models were factory certified with
the 17.6m tips.
-- Regarding the air brakes, I have never found a situation where
landing flap and full dive brakes were inadaqute. That said, they
probably are not the equal of a PIK 20B or any other ship with full
90deg flaps (I've got about 2500 hrs in a 20B, before the Ventus).
Hope this helps your decision.
Bob
Jim Pengelly
Apr 18, 2012, 3:43:02 PM4/18/12
to
think I'm going to get one if I can find the right one for the right
price. Any ideas on current values?
Jim Pengelly
Apr 18, 2012, 3:40:52 PM4/18/12
to
At 03:36 18 April 2012, Bob Gibbons wrote:
>On Tue, 17 Apr 2012 12:46:24 +0000, Jim Pengelly
>On Tue, 17 Apr 2012 12:46:24 +0000, Jim Pengelly
made up. Now it's just a question of finding the right one.
>
John Ferguson
Apr 18, 2012, 4:20:39 PM4/18/12
to
In the UK Discus bT go for as much as £49k, Ventus cT are less expensive,
probably because of the reputation. UK prices for Ventus cT is £42k to
£45k.
probably because of the reputation. UK prices for Ventus cT is £42k to
£45k.
nov...@gmail.com
Apr 18, 2012, 6:58:28 PM4/18/12
to
Hi Jim,
I can't add anything to the discussion for the turbo model but I have been flying the pure sailplane version Ventus C for about 6 years. The C model is as docile as can be imagined and the performance is great. Unless you want to compete in the 15 meter class, I can't ever imagine that you would fly it in other than the 17.5 meter configuration.
Bob
BV
I can't add anything to the discussion for the turbo model but I have been flying the pure sailplane version Ventus C for about 6 years. The C model is as docile as can be imagined and the performance is great. Unless you want to compete in the 15 meter class, I can't ever imagine that you would fly it in other than the 17.5 meter configuration.
Bob
BV
Message has been deleted
Peter F
Apr 20, 2012, 4:43:49 AM4/20/12
to
At 03:36 18 April 2012, Bob Gibbons wrote:
>-- Max gross with or without the engine is 500kg. The issue with the
>engine in place is the 255kg non-lifting limit. With the engine in
>place, the pilot weight determines whether the max gross of 500kg or
>the non-lifting limit of 255kg kicks in first.
You've lost me somewhere.
>engine in place is the 255kg non-lifting limit. With the engine in
>place, the pilot weight determines whether the max gross of 500kg or
>the non-lifting limit of 255kg kicks in first.
Why does pilot weight stop you getting to max gross as long as the wing
tanks are big enough?
Assuming tanks *are* big enough to get to max gross without the engine then
it should be a piece of cake to get there *with* the engine.
PF
Peter Purdie
Apr 20, 2012, 5:56:51 AM4/20/12
to
If pilot + other non-lifting parts exceeds 255kg, then you can't fly. If
you can fly, then you can water up to the 500kg limit.
Indeed, it should be beneficial as water in the wings reduces wing root
bending. It increses bending at the end of the tank area, but the
manufacturer should have taken care of that.........
you can fly, then you can water up to the 500kg limit.
Indeed, it should be beneficial as water in the wings reduces wing root
bending. It increses bending at the end of the tank area, but the
manufacturer should have taken care of that.........
MN50
Apr 20, 2012, 10:38:25 AM4/20/12
to
>
> - Show quoted text -
The Ventus (and nearly all gliders out there) fuselage is hanging from
the wings by four pins. On the Ventus they are about 15-20 mm in
diameter. The non-lifting weight limit is the maximum load those pins
can support and is unchanged by the extra weight water ballast adds.
Peter F
Apr 20, 2012, 11:32:00 AM4/20/12
to
Yes I know what max weight of non-lifting parts is.
If you can fly at all, you can fly at max gross.
I'm just confused by Bob Gibbons post (See quote below)
For his weight the margin on non-lifting limit is the same with or without
water the 28gals is irrelevant.
PF
Quote
-- Max gross with or without the engine is 500kg. The issue with the
engine in place is the 255kg non-lifting limit. With the engine in
place, the pilot weight determines whether the max gross of 500kg or
If you can fly at all, you can fly at max gross.
I'm just confused by Bob Gibbons post (See quote below)
For his weight the margin on non-lifting limit is the same with or without
water the 28gals is irrelevant.
PF
Quote
-- Max gross with or without the engine is 500kg. The issue with the
engine in place is the 255kg non-lifting limit. With the engine in
place, the pilot weight determines whether the max gross of 500kg or
the non-lifting limit of 255kg kicks in first. For my weight and 28
gal of water, I hit max gross just before I hit the non-lifting limit.
End Quote
gal of water, I hit max gross just before I hit the non-lifting limit.
Bob Gibbons
Apr 20, 2012, 8:26:44 PM4/20/12
to
On Fri, 20 Apr 2012 02:59:15 +0000, Ventus_a
<Ventus_a...@aviationbanter.com> wrote:
>'Bob Gibbons[_2_ Wrote:
... text deleted
>> -- Max gross with or without the engine is 500kg. The issue with the
>> engine in place is the 255kg non-lifting limit. With the engine in
>> place, the pilot weight determines whether the max gross of 500kg or
>> the non-lifting limit of 255kg kicks in first. For my weight and 28
>> gal of water, I hit max gross just before I hit the non-lifting limit.
>> Bottom line, with the engine in place and ballasted to max gross, you
>> are at the same loading as without the engine, but you cannot dump
>> down to the same low loading as without the engine. With the engine
>> in, I can go from 10.1 lbs/ft2 max down to 7.9 lbs/ft2 min. Without
>> the engine, W/L ranges from the same 10.1 lbs/ft2 down to 7.2 lbs/ft2
>> (all with 17.6m span). The B model has the same issue and limitations.
>>
>
>Every Ventus cT manual that I have looked at says the max weight with
>the engine in is 430 kg regardless of the span. With the engine out,
>500kg at 16.6. and 17.6m respectively
>
>Cheers
>Colin
Colin, you are correct in quoting the handbook. Several of us actually
discussed this apparent contradiction with Klaus Holighaus on a visit
a number of years ago.
He agreed that it so long as the non-lifting limit is followed, it
makes no difference whether the engine is in or out.
The engine represents a fuselage (non-lifting) load on the airframe,
the cause of this non-lifting load should not be a factor in the
overall gross weight, so long as the non-lifting limit is observed.
Bob
<Ventus_a...@aviationbanter.com> wrote:
>'Bob Gibbons[_2_ Wrote:
... text deleted
>> -- Max gross with or without the engine is 500kg. The issue with the
>> engine in place is the 255kg non-lifting limit. With the engine in
>> place, the pilot weight determines whether the max gross of 500kg or
>> the non-lifting limit of 255kg kicks in first. For my weight and 28
>> gal of water, I hit max gross just before I hit the non-lifting limit.
>> Bottom line, with the engine in place and ballasted to max gross, you
>> are at the same loading as without the engine, but you cannot dump
>> down to the same low loading as without the engine. With the engine
>> in, I can go from 10.1 lbs/ft2 max down to 7.9 lbs/ft2 min. Without
>> the engine, W/L ranges from the same 10.1 lbs/ft2 down to 7.2 lbs/ft2
>> (all with 17.6m span). The B model has the same issue and limitations.
>>
>
>the engine in is 430 kg regardless of the span. With the engine out,
>500kg at 16.6. and 17.6m respectively
>
>Cheers
>Colin
Colin, you are correct in quoting the handbook. Several of us actually
discussed this apparent contradiction with Klaus Holighaus on a visit
a number of years ago.
He agreed that it so long as the non-lifting limit is followed, it
makes no difference whether the engine is in or out.
The engine represents a fuselage (non-lifting) load on the airframe,
the cause of this non-lifting load should not be a factor in the
overall gross weight, so long as the non-lifting limit is observed.
Bob
Bob Gibbons
Apr 20, 2012, 8:51:40 PM4/20/12
to
On Fri, 20 Apr 2012 08:43:49 +0000, Peter F <ls4...@yahoo.co.uk>
wrote:
PF, I agree this was a confusing way to state the situation. As you
correctly point out, if you satisfy the 255kg non-lifting limit, you
can ballast up to the 500kg limit irrespective of the pilot weight.
What I was trying to convey is that a lighter pilot can get more
margin under the non-lifting limit, and thus add more water ballast
before reaching the 500kg limit.
As I mentioned, at my weight, I am right at the 255kg limit with the
engine in place. I can add 28 gal before I hit 500kg.
If I weighed 20 lbs less, I could load in 31 gal before hitting the
500kg limit.
Or if I take out the engine, I can put in 40 gal before hitting the
500kg limit.
Sorry for the poor wording.
Bob
wrote:
correctly point out, if you satisfy the 255kg non-lifting limit, you
can ballast up to the 500kg limit irrespective of the pilot weight.
What I was trying to convey is that a lighter pilot can get more
margin under the non-lifting limit, and thus add more water ballast
before reaching the 500kg limit.
As I mentioned, at my weight, I am right at the 255kg limit with the
engine in place. I can add 28 gal before I hit 500kg.
If I weighed 20 lbs less, I could load in 31 gal before hitting the
500kg limit.
Or if I take out the engine, I can put in 40 gal before hitting the
500kg limit.
Sorry for the poor wording.
Bob
Bob Gibbons
Apr 20, 2012, 8:59:25 PM4/20/12
to
non-lifting limitation.
What I was trying to convey is the impact of the pilot weight on the
amount of water ballast you can add before hitting the max gross
limit.
As I mentioned, at my weight, I can add 28 gal before reaching max
gross of 500kg. With the engine installed, I am right at the 255kg
non-lifting limit.
On the other hand, if I weighed 20 lbs less, I could add 31 gal of
water before reaching the 500kg limit.
If I took the engine out, I could add 40 gal of water before reaching
the 500kg limit.
Sorry for the confusion.
Bob
foxje...@gmail.com
Jan 20, 2014, 3:28:36 AM1/20/14
to
Interesting I have bT and my Manual says max. 270 kg for non lifting parts.
David Hirst
Jun 25, 2019, 3:08:39 PM6/25/19
to
On Saturday, April 21, 2012 at 12:26:44 PM UTC+12, Bob Gibbons wrote:
>
> >Every Ventus cT manual that I have looked at says the max weight with
> >the engine in is 430 kg regardless of the span. With the engine out,
> >500kg at 16.6. and 17.6m respectively
> >
> >Cheers
> >Colin
>
> Colin, you are correct in quoting the handbook. Several of us actually
> discussed this apparent contradiction with Klaus Holighaus on a visit
> a number of years ago.
>
> He agreed that it so long as the non-lifting limit is followed, it
> makes no difference whether the engine is in or out.
>
> The engine represents a fuselage (non-lifting) load on the airframe,
> the cause of this non-lifting load should not be a factor in the
> overall gross weight, so long as the non-lifting limit is observed.
>
> Bob
Sorry, but I'm still confused.
>
> >Every Ventus cT manual that I have looked at says the max weight with
> >the engine in is 430 kg regardless of the span. With the engine out,
> >500kg at 16.6. and 17.6m respectively
> >
> >Cheers
> >Colin
>
> Colin, you are correct in quoting the handbook. Several of us actually
> discussed this apparent contradiction with Klaus Holighaus on a visit
> a number of years ago.
>
> He agreed that it so long as the non-lifting limit is followed, it
> makes no difference whether the engine is in or out.
>
> The engine represents a fuselage (non-lifting) load on the airframe,
> the cause of this non-lifting load should not be a factor in the
> overall gross weight, so long as the non-lifting limit is observed.
>
> Bob
To my mind, a non-lifting limit is a hard limit, defined by the mechanical limit of the four wing-root pins. If you remove the engine (and fuel tank and engine battery) then this limit should not change; you've taken weight off the pins so can add more pilot weight etc. (ignoring balance considerations for the moment).
What the flight namual seems to be implying (and thanks, Colin, for the discussions) is that there are some wing bending issues. The (non-turbo) Ventus was designed for a MAUW of 500kg and the wing will cope fine with a max non-lifting weight of 255kg (for example - it varies depending on the model). What the manual seems to be implying is that SH then wanted to put a turbo in but came up against the (true) load limit of the wing pins, as well as some bending moment limitations on the wing, but the market need for a turbo version was great so they put a 430kg limitation on the MAUW.
I know that there are cT/bT pilots out there who ignore the 430kg limit and ballast up to 500kg with no issues. I'm asking the Collective Wisdom of y'all whether:
a) my reasoning above is correct;
b) whether to take the numbers in the flight manual with a grain of salt, bearing in mind the discussions with Herr Holigaus; and
c) whether it's worth asking SH to revise the flight manual to clear up the confusion; or
d) to obey the flight manual at all times and loads.
Answers on a postcard...
DH
TX
0 new messages