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Contacttower
16th Dec 2007, 12:31
I know twins have been covered before....but, out of those three which is the best for the MEP and which is the superior plane (in terms of performance, load carrying etc)?

(The prices are all about the same).

DFC
16th Dec 2007, 12:53
For up to four seat touring, the Twin Comm wins hands down.

Aztec is also really only a four seater but has a problem in that if a particular engine fails you have lost not just the engine but also other systems.

The Senneca 1 is also just a 4 person aircraft but with 6 seats so great if you have lots of children but also has the aileron - rudder link that reduces the crosswind limit to 12 knots.

As a twin with up to 9 hours endurance the twin comm is an ideal aircraft.

The tip tanks alone can get you to Alderney from the London area with IFR reserves.

Regards,

DFC

SNS3Guppy
16th Dec 2007, 14:05
The Twin Commanche is faster. The Aztec is roomier. The Seneca is a little closer to modern and like the Aztec, has very mild flying characteristics. Of the three, the least relatively underpowered is the Commanche, but it will also bite you if you get it in the wrong place.

All three are typical underpowered light twins. You gain an advantage in speed and rate of climb over a single such as a Cessna 206 or 207, but at the sacrifice of safety in the event of an engine failure; both are going down, one just does it faster than the other (while facing directional control issues). Properly flown, any of them can be comfortable airplanes.

We had a twin commanche at an ag operation where I flew years ago. I never liked it. The Apache and Aztecs were great airplanes, but slow. Nice headroom, if that's important to you. The commanche was more like flying a mooney; small inside, and had a similiar ride. I flew Senecas for a time off rough fields and to some remote locations in the mountains. I mostly flew the Seneca II and III, which are turbocharged and do much better at altitude. As a light twin, the II's and III's were some of the few that could maintain 8,000 on one engine with a full load.

Bear in mind when shopping for a twin that it's not a slight increase from single engine ownership. The retractable gear, second engine, and increasd maintenance, added insurance, larger tie-down or hangar space, and so on is more like a three fold increase in costs, vs. a two fold increase. Older twins can be had for a good price, but at a price. Have a very thorough inspection done. I've seen a lot of singles that run thousands of dollars at the first annual inspection, due to the things which need to be repaired. I've seen twins run considerably more.

Fly them all and see what you think; get the pilot handbooks and run the performance numbers for the different scenarios in which you envision using the airplane, and see what adds up. Remember that each of those airplanes were originally type certificated under regulations not requiring actual performance numbers (much of the data is interpolated, and is ideal for a new airplane with a new engine and new propeller, flown by a factory pilot under specific conditions)...and none of them were required to maintain altitude on one engine with any significant load.

Good luck.

Contacttower
16th Dec 2007, 14:29
DFC, SNS3Guppy, many thanks for your thoughts.


but also has the aileron - rudder link that reduces the crosswind limit to 12 knots.



I don't like the sound of that, good crosswind is quite important.

jabberwok
16th Dec 2007, 15:16
Much as I liked our Aztec a point to keep in mind is that it has an AUW of 2359kg. Anything over two metric tonnes incurs higher charges and these can mount up on a busy aircraft.

Some Seneca's are downrated to 1995kg which makes them more appealing.

Fuji Abound
16th Dec 2007, 15:34
Are we talking about the PA23 with the 540 engines and six seats?

Contacttower
16th Dec 2007, 16:01
Are we talking about the PA23 with the 540 engines and six seats?


Yeah, as oppposed to the older Apache.

englishal
16th Dec 2007, 16:31
I'm not sure about the other two, but I'd steer clear of the Seneca I. The Seneca II is a different animal though.

bookworm
16th Dec 2007, 16:44
For up to four seat touring, the Twin Comm wins hands down.

While I would generally agree with your sentiments DFC (and I wouldn't swap our Twin Com for anything else), most Twin Coms with reasonable kit are not capable of carrying 4 normal adults on a typical tour. With 4 adults plus light baggage and a dinghy, you're down to about 3 hours to dry tanks. Factoring in IFR reserves and the odd alternate that's 45 mins away, that doesn't give much flexibility.

If you're regularly flying 4-up, go for something with a higher load capability.

IO540
16th Dec 2007, 18:03
Some Seneca's are downrated to 1995kg which makes them more appealing

I know close to nothing about twins (though amazingly I did land one today, mind you that one did have both engines running) but the above can make a vast difference to operating costs if one is to use it for serious European touring.

I would recommend looking up the IFR route charges. About 200 on a decent leg across Europe. That is going to be about half the cost of the avgas!

Somebody thinking they are going to fly a de-iced plane (SE or ME) under "official VFR" (i.e. in IMC if necessary) in N European weather, is in for a suprise. A decent operating ceiling is a must, i.e. FL160+, for airways flight.

lady in red
16th Dec 2007, 18:57
I have flown all types mentioned. The Seneca I does not have good single engine climb performance. The Aztec is a big bus with 50s style technology but lots of people like the roominess in them. The Twin Com would be my favourite if it is the PA39 rather than the PA30 - the latter has a vicious stall.
But if you had a choice, then the Seneca 3 has far better performance and my current favourite twin is the BE76 Duchess - a very good training and touring aircraft with 25 knot crosswind capability.

bookworm
16th Dec 2007, 19:15
The Twin Com would be my favourite if it is the PA39 rather than the PA30 - the latter has a vicious stall.

Nah, it's a kitten, particularly with vortex generators fitted. Does the PA39 have airframe difference that affect the stall? I thought it was just contra-rotating props.

B2N2
16th Dec 2007, 20:29
Aztec is also really only a four seater but has a problem in that if a particular engine fails you have lost not just the engine but also other systems

Our 1966 Aztec C had a usefull load of almost 2200lbs with a max T/O weight of 5200lbs.
I don't call that a 4 person airplane by a lot shot, that's 6 plus luggage plus full fuel.

Aztec slower then a Twin Comanche? I flight planned ours at 160 kts TAS and that was at 21" MP and 2300 RPM.

Aztec's are available in many different flavors, we had dual vacuum pumps but the hydraulic pump ( flaps & gear) was on the left engine.
There is an STC for dual pumps.

Here's a nice one:
http://www.aso.com/aircraft/92749/ext-2.jpg

The link is here:

http://www.aso.com/i.aso3/aircraft_view.jsp?aircraft_id=92749&return_url=/i.aso3/search.jspyyyyyiaso3sid=1xxxxxtypeid=2xxxxxsearchid=13872391 xxxxxregionid=-1xxxxxmode=xxxxxtypeid=2xxxxxmmgid=14xxxxxmodelgroup=truexxx xxsearchid=13872391xxxxxregionid=-1

My vote goes to the Aztec.....:ok:

421C
16th Dec 2007, 21:03
I'd see the trade-offs amongst the 3 as

Aztec - very cheap to buy with great payload and short-field performance and good speed and range. Oddly dated-looking (IMHO), single-door overwing cabin access not nice for pax, >2t and more expensive to run than the lighter twins.

Comanche - a very efficient design which has the low cost to run of the sub 2t twins but the speed of the larger ones.

Seneca 1 - I admit I have 500hrs in these and I like them more than the other normally aspirated twins (Duchess, Seminole, Cougar). I don't know why they get such a bad rap on forums. They are more modern looking, the cabin is big and wide (much more comfortable than the Beech twins) and the aft door and seats are very nice for pax. They cost approx. Comanche/Duchess money to run (under 2 tons, 200hp a side).

The demostrated crosswind of 13kts is a non-issue (and not a legal limit in any way). I found them no harder to land safely in 25kt xwinds than other aircraft.

The Seneca 1 single engine performance is no worse than other normally aspirated twins - ie. adequate once a safe height and speed are reached after take-off from the great majority of airports you'll depart from, and adequate for cruise over most terrain. Even over the alps, the drift down performance will give you a lot of options to land safely. The non-turbo IO360s are pretty bullet proof, and will cruise nicely at 6000', 18 US gals/hr total, 65% power, ~155KTAS.

The Seneca 1 was the best selling light twin in its day (ok, 1972-74) for a reason. It does nothing brilliantly (except perhaps the cabin space, about as nice as it gets below the "cabin class" piston aircraft like the Navajo/340/Duke) but it does a lot of things ok.

It really depends on your mission. High utility IFR - the Aztec. Fast economical touring - the Comanche. A fairly economical twin with a big cabin - the Seneca 1.

Contacttower
16th Dec 2007, 21:09
The demostrated crosswind of 13kts is a non-issue (and not a legal limit in any way). I found them no harder to land safely in 25kt xwinds than other aircraft.



421C exactly what effect does having the rudder/aileron interlink have?

I've never flown a plane with one...but I'd have thought that a crosswind technique like crabbing in and then transitioning to wing low over the threshold (which is what I do) is difficult because of the need to cross the controls over.

Fuji Abound
16th Dec 2007, 21:17
Our 1966 Aztec C had a usefull load of almost 2200lbs with a max T/O weight of 5200lbs.

I agree.

I asked the question because some of the answers did resemble those from someone who had actually flown a later generation Aztec.

Personally, I think the Aztec is the best of this bunch. Bullet proof in most respects, copes very well with weather and huge carrying capability with very good single engine performace.

Just watch the door opening mechanism!

If you have the money, buy a tatty one and have it refurbished, new panel, zero timed engines and you will have more than enough change left over from the cost of a new twin to pay for the fuel.

421C
16th Dec 2007, 21:23
Contacttower,
I am embarrassed to say I don't really know what effect it has, except to say not much.

This isn't just bravado; and I'm not claiming a demonstrated x-wind limit should be lightly ignored. It's just that I started cautiously when I transitioned to the Seneca 1 (my first twin type) and it was never a problem to land in strong crosswinds, not even close to a problem. Being safe in a light twin demands all sorts of things (eg. recurrent training in single engine drills) and the x-wind thing just wasn't on that list of demanding things.

rgds
421C

421C
16th Dec 2007, 21:29
If you have the money, buy a tatty one and have it refurbished, new panel, zero timed engines and you will have more than enough change left over from the cost of a new twin to pay for the fuel


The problem with this approach is that when you come to sell it, it will be worth......not much more than a tatty one. The market in old twins is brutal in this way. You have to be sure you will amortise the money over a long ownership period.

The best aircraft to buy is a twin where the previous owner has done what Fuji suggests!

DFC
16th Dec 2007, 21:35
Bookworm,

I did say "up to". However, in such an aircraft 3 hours is not bad when you take in bladder endurance.

However, 3 hours flying is 21 gallons per side i.e. 42 USG total. Can be 18 a side if I am careful or even less with a tailwind.

You must have some heavy friends.

-----------

I don't call that a 4 person airplane by a lot shot, that's 6 plus luggage plus full fuel.

Have you had to sit (as an adult) in the back row for any length of time?

I am not big but it is far from comfortable.

However, 2 Adults and 4 Children works a treat.

Regards,

DFC

S-Works
16th Dec 2007, 21:40
I have flown all three and I do like the Aztruck a lot. But like 421 I have several hundred hours in the Seneca range with majority in the One and it is a good work horse.

The interlink on the controls just means you have to be a bit more adaptive in strong winds but has never been a problem.

They are cheap in twin terms to operate and reliable. The one I fly is deiced and IFR equipped, being my winter mount when it gets a bit icy for the Cessna!

Fuji Abound
16th Dec 2007, 21:40
Have you had to sit (as an adult) in the back row for any length of time?

Now that is very true.

Also single engine climb is pretty good - definitely not in the marginal category.

bookworm
16th Dec 2007, 21:48
However, 3 hours flying is 21 gallons per side i.e. 42 USG total. Can be 18 a side if I am careful or even less with a tailwind.

You must have some heavy friends.

Light friends, heavy aeroplane. ;) With 4 x 180 lb people and 70 lb baggage (excluding the emergency equipment) I get 38 USG in. My rule of thumb is 14 USG/hr (which includes a contingency) + 4 USG excess for t/o and climb. So that's 1.75 hours to destination and alternate + 0.75 hr FRF.

DFC
16th Dec 2007, 22:07
The interlink on the controls just means you have to be a bit more adaptive in strong winds but has never been a problem

The interlink on the controls means that when you apply left rudder, the control column rotates left and thus applies left down aileron.

This means that when you are landing in a right crosswind, when you kick it straight with the left rudder you will get left roll caused by the yaw and increased by the input of interlinked aileron.

It is not something that you can be adaptive about and the later models with this removed have higher crosswind limits.

---------

Bookworm,

I would not describe 3 13 stone friends as being "light".

Surprised that your limited by so much.

Thus you must spend a lot of time with the aux and tip tanks empty. Does this cause a problem with the bladder in the aux tanks drying out?

I can't believe that you can only carry round about 1/3 of the aircraft fuel capacity when going flying. I have not had such a problem. OK, not full tanks and full seats but I am sure we could carry more fuel than that.

Have you had your aircraft weighed recently?

Regards,

DFC

SNS3Guppy
16th Dec 2007, 23:27
If I were in the market for a light twin personally, I'd be shopping for either a Cessna 310 or a Beech Travel Air. Both can still be had for good prices and have much better performance in my opinion. I wouldn't consider either of them a six place airplane, of course...but then one of the only light twins I'd put six people in would be a Twin Commander.

Think about your mission. Sometimes people start looking for an airplane based on the largest amount of people they might carry, when 90% of their missions will be solo. If that's the case, you're better buying something suited to the majority of your flying, and rent or otherwise improvise when the occasional need comes up to do more.

On-MarkBob
17th Dec 2007, 02:31
There is another twin, so far not given a thought here. Generally cheeper to buy than the others, even when fully equipped with de-icing equipment. Good short field performance, good range, six persons (just) four with baggage, easy passenger access (with the exception of the very rear seats), reliable and just as cheep to maintain as the Seneca and certainly cheeper than an old Aztec. Intrested? Not everyones cup of tea mind you, but if its twin engine safety and reliability you want above anything else then take a look at the good old Cessna 337 Skymaster. The Twin boom Push-me Pull-you.

SNS3Guppy
17th Dec 2007, 04:13
The skymaster is okay when both engines are running. It's not when one isn't. It also puts you in a position between two weights with fuel all around, and hot exhuast at each end, a considerable amount of noise, and one way out if the cabin's bent.

S-Works
17th Dec 2007, 07:10
This means that when you are landing in a right crosswind, when you kick it straight with the left rudder you will get left roll caused by the yaw and increased by the input of interlinked aileron.

It is not something that you can be adaptive about and the later models with this removed have higher crosswind limits.

Dunno about that mate, it may be a difficult concept for you but I have managed for well over 500hrs to put it down in some howling winds. I guess it's what you get used to.

bookworm
17th Dec 2007, 07:55
Surprised that your limited by so much.

Thus you must spend a lot of time with the aux and tip tanks empty. Does this cause a problem with the bladder in the aux tanks drying out?


On the contrary, I very rarely put 4 people in the aeroplane.

Have you had your aircraft weighed recently?

Much more often and recently than most aircraft, I think. 2610 lb. I obviously can't speak for the aircraft you fly/flew, but I get the impression that a lot of owners/operators do a lot to avoid having their aircraft reweighed for fear of bad news.

Fuji Abound
17th Dec 2007, 10:21
Dunno about that mate, it may be a difficult concept for you but I have managed for well over 500hrs to put it down in some howling winds. I guess it's what you get used to.

Luving it.

:ok: :D

Fuji Abound
17th Dec 2007, 10:32
:confused:

What are you going on about?

I thought with 500 hours on type is was a sound comment.

S-Works
17th Dec 2007, 11:07
In which case I humbly apologise. Perhaps I still have a raw nerve or two.

Fuji Abound
17th Dec 2007, 11:15
No problem, and no need.

I appreciate you dont agree with my approach, but hopefully it is not something we ever need to really fall out over.

:)

AC-DC
17th Dec 2007, 15:14
Bookworm wrote:
...most Twin Coms with reasonable kit are not capable of carrying 4 normal adults on a typical tour. With 4 adults plus light baggage and a dinghy, you're down to about 3 hours to dry tanks.

I have a problem with your numbers.
If you have tip tanks you can carry 90gl but your W&B shows only the 60gl in your main tanks (keep your AUX empty), the tip's fuel is FREE weight, that is 180lbs that you can forget about. 90gl @14gl/h should give you 6.5h to empty tanks or 1040nm. As far as I can recall your aircraft has tips or am i wrong?

ACDC

bookworm
17th Dec 2007, 17:06
Haven't got the spreadsheet in front of me but from memory...

I'm assuming the tips are carrying at least 125 lb of the fuel, hence the MTWA is 3725 lb. With the tips empty, I'm down to 3600 lb MTWA

2610 lb aircraft
720 lb people
70 lb baggage
20 lb anti-ice
75 lb emergency equipment (mostly the 4 man dinghy), tools, cover etc.
230 lb fuel = 38 USG (of which at least 21 USG must be in the tips)

Total 3725 lb.

TwinkieFlyer
17th Dec 2007, 18:41
2610 has to be a turbo Twin Comanche. A non-turbo would be more like 2450 to 2500. Gross with tips is 3725 IF you have at least 125 pounds fuel in the tips. Otherwise gross is 3600. There are some Robertsons with gross of 3800.

A Twin Comanche is a great airplane IF you don't get into icing. With only 160hp per side, it isn't going to handle ice very well. It will do 165k easily on 16 US gallons/hour, and 155k on 14.5, and that is total, both engines.

A non-Trubo, 5:15 total fuel at 16gph.

And no, it doesn't cost twice as much as a single to run, the reason is the systems are so much simpler than most twins.

If you want to carry a big load and deal with some ice, buy an aztec, they may be ugly, and they burn a lot of fuel, but they will fly through a lot of messy weather.

aztruck
18th Dec 2007, 18:52
Aztec, but get a good one and look after it. Rock solid in cloud, almost the same payload as a Navajo, built like a tank and handles grass, mud and gravel no problem. lowest fatal accident record of any twin. bit noisy in the cabin - get anr headsets for passengers and yourselves.
Get a good E model, and stay clear of the turbo ones.
500 m wet grass, 6 up into st Mary's scilly isles, Stuttgart/London night IFR 6 up...takes it all in its stride. Bit thirsty. Nip over to alderney with those big fat longrange tanks and fill her up!

bookworm
19th Dec 2007, 08:43
2610 has to be a turbo Twin Comanche.
...
A Twin Comanche is a great airplane IF you don't get into icing.

Nope, not a turbo, but with de-ice (boots and prop anti-ice).

AC-DC
21st Dec 2007, 19:20
Bookworm

Your aircraft is an heavy one. You can store 30gl in he tips (180lbs) that can be kept out of your W&B. In any case, flying 4 men is always hard. I did it but had to leave the cover behind, then I was 20lbs below Max.

bookworm
22nd Dec 2007, 08:32
Your aircraft is an heavy one.

That may be the case. But the only other person I've known who has bought a Twin Com also got a nasty surprise when he got the real W&B sheet. The message is clear -- weigh before you buy.

You can store 30gl in he tips (180lbs) that can be kept out of your W&B.

That's a strange way of putting it, and numerically incorrect. The installation of tip tanks increases the MTWA from 3600 lb to 3725 lb, with the condition that any weight in excess of 3600 lb is fuel in the tip tanks. So in essence you can have 21 USG (125 lb) in the tip tanks without having any impact on the passenger and baggage load.

DFC
22nd Dec 2007, 08:54
That's a strange way of putting it, and numerically incorrect. The installation of tip tanks increases the MTWA from 3600 lb to 3725 lb, with the condition that any weight in excess of 3600 lb is fuel in the tip tanks. So in essence you can have 21 USG (125 lb) in the tip tanks without having any impact on the passenger and baggage load.

Now that is 1.5 hours at normal cruise power settings.

Thus one could use that fuel for a 1 hour diversion at long range cruise and a 45 minute hold at max endurance power all including contingency.

That leaves all the rest of the fuel you carry to get you to destination.

There are very few such aircraft where the limiting factor is not the endurance of your bladder!

Regards,

DFC

bookworm
22nd Dec 2007, 11:14
That leaves all the rest of the fuel you carry to get you to destination.

Yup. All 17 USG of it. ;) That's typically about 55 mins after an allowance for take-off and climb.

I've already said I wouldn't swap the Twin Com for anything else. Just bear in mind that as four-plus-bags aircraft, it's very different from what it's capable of as a two-person (3:10 to dest) or even three-person (5:30 to dest) tourer.

TwinkieFlyer
22nd Dec 2007, 17:08
BookWorm, is the weight penalty of the de-ice worth the advantages in your experience? Must be about 125-145 pounds the best I can figure.

bookworm
23rd Dec 2007, 08:28
is the weight penalty of the de-ice worth the advantages in your experience? Must be about 125-145 pounds the best I can figure.

Difficult one to judge. If I count the value as the number of times the boots have actually been used, the answer is "no". If I count the value as the number of trips I didn't cancel and the stress avoided because they were there, the answer is "yes". To be honest, I rarely operate the aircraft as a tourer with more than 2 up, so the penalty is not a bit issue.

I don't think the penalty is really 125-145 lb, though the nitrogen bottle and plumbing is indeed heavy (from a CofG point of view I wish it were in the back rather than the nose). I think we really do have a heavy aeroplane compared to some of its peers - probably all that filler needed to compensate for the abuse over 40 years. ;)

wac flyer
2nd Jan 2008, 15:30
they must be four BIG people to reach the all up on an Aztec! For an easy to fly, spacious twin I would opt for the Aztec BUT dont forget those nav charges. For training I would agree with the recommendation of the duchess. Simple and forgiving!

Contacttower
5th Jan 2008, 11:36
Just had my first lesson in the Twin Comanche and I really like it. Only thing which irritated me about it was the manner of the landing...very flat (with just two in the front) and hard, it just seems to float and then drop, not like the PA28 at all. Could anyone offer any advice on how to make the landings better? I'm told all the Piper light twins are like this.

poor southerner
5th Jan 2008, 14:44
i think anything from an arrow upwards lands like that.

As only only one person mentioned, the Cessna 337 is a little known good twin. Yes there is the prop noise, but with plenty of power on tap you can help with lower rpm take offs if light. also the engine tbo is 1500 hrs, but most non turbos seem to make it happily. They have a good turn of speed and load up well. Single engine performance is good on all models, exepct when cycling the gear you will sink with the drap from the clam sheel rear doors !. They also seem to go for good $$.

I remember my ir training in the dutchess. A wonderfull aircraft, with a good sized panel to fill and a nice height position, but they only ever seem to be used for training and everyone i,ve been in showed it with wear and tear.

Tony Hirst
5th Jan 2008, 15:59
The 337 looks like a fabulous aircraft. When (if) the readies avail themselves, one shall be mine!
I'm told all the Piper light twins are like this.My impression was that the Seneca 1 was definitely more tricky than the Seneca III which was more difficult than the Arrow t-tail which I was told was difficult.

However, the Seneca I and Arrow both have very heavy elevator forces in common, you think you've run out of authority but with more determination you discover there is movement yet. Just that judgement, probably very subjectively on my part, seemed to be more difficult in the Seneca 1.

Perhaps the Twin Comm is like the Seneca 1? The Seneca 1 definitely likes power to remain on until starting the flare with a fair amount of rearward trim. The rearward trim does not cause excessive control forces when going around which is good. It should be positively landed on the mains (greasers just increase the ground roll) with a good flare and the stick hard back as you brake until the nose cannot stay up any longer. This produces satisfyingly short landing runs.

SNS3Guppy
5th Jan 2008, 16:52
The arrow doesn't have heavy control forces, with a stabilator all-flying tail. The Seneca doesn't either. The Seneca (I, II, or III) is about as benign and easy to fly as any light twin, and has very simple handling characteristics with it's square, hershey bar wing.

The Cessna 337 is okay until one engine fails, when you're sandwiched between to heavy weights and in a cage with one exit and avgas on top. While they don't have assymetrical thrust issues, they have very poor single engine performance, and unless you're flying an upgraded airplane such as a Riley conversion or an airplane with bigger engines, you're going to be drifting down, not climbing, not holding altitude on one engine.

Contacttower
5th Jan 2008, 17:16
:hmm:...I found the controls light at all times in the Twin Comm, except during the flare, certainly the flare was a lot heavier than the low tailed Arrow. My instructor (A very experienced one I might add) seemed to think that realistically it wouldn't land much better than what I managed. The other issue I discovered was a bit of PIO during the flare...caused by me lowering the nose slightly after the initial flare to loose a bit of height (having perhaps flared a little high at first) and then trying to raise the nose again closer to the ground. Anyone else like to share experiences of the type?

Tony Hirst
5th Jan 2008, 18:19
CT,

I think that pretty much describes the Seneca 1 too! Understood that such a perception is possibly subjective and relative to one's usual steeds.

poor southerner
5th Jan 2008, 18:27
guppy
well I have only flown early model 337's (non turbo or P) and I never had any problems with either single engine climb, with various loads. The only problem is the well know gear retraction drag brake (which can be fixed with a stc door deletion kit)
I would liken flying a 337 on one engine to flying a 182.

and if you dont like not having a driver door, best avoid flying most pipers or anything larger

bookworm
5th Jan 2008, 19:17
Only thing which irritated me about it was the manner of the landing...very flat (with just two in the front) and hard, it just seems to float and then drop, not like the PA28 at all. Could anyone offer any advice on how to make the landings better? I'm told all the Piper light twins are like this.

Welcome to the game of chance called "landing the Twin Com". :) The unpredictability of landing seems to be a standing joke among TC owners.

I think the fundamental problem (probably not shared by other Piper twins) is the high deck angle in the normal ground attitude. It was supposed to be so the passengers could climb straight on to the aft wing without a step. A consequence seems to be an uncomfortably narrow window between that ground attitude (at which you just about avoid breaking the nosewheel) and the stall attitude. Vortex generators seem to help.

Contacttower
5th Jan 2008, 22:33
I found an old Fliteguide test of the Twin Com on the internet and it suggests to deal with the landing:

There are two main schools of thought on how to minimise landing embarrassment. The first is to use half flaps, which will get the Twin Comanche down sooner and with less of a sudden cessation of flying. The second is to simply pump up the main gear legs to maximise their extension length. This addresses two of the main causes; it reduces the nose high stance and increases the gap between the flaps and the ground. Either way the PA-30 is an aeroplane that will punish sloppy technique.

SNS3Guppy
6th Jan 2008, 05:16
well I have only flown early model 337's (non turbo or P) and I never had any problems with either single engine climb, with various loads. The only problem is the well know gear retraction drag brake (which can be fixed with a stc door deletion kit)
I would liken flying a 337 on one engine to flying a 182.


Now of course you'll need to specify if it's the front engine or the rear, beause the performance is different for each. That said, what kind of single engine ceiling have you been at gross weight with an engine out? If you're limping home close to sea level with no significant terrain beneath, perhaps it's okay.

It's certainly not akin to flying a 182. Among other things, with the 182, I've regularly dropped loads of skydivers out at 15,000 feet and higher...something you'll not being doing on one engine in the 0-2/337. In fact, even at low altitudes, you won't meet the same rate of climb on one engine as a 182...and one one engine you're in an emergency condition in the 337, whereas you're perfectly fine in the 182. Furthermore, lose the remaining engine in the 337, you shouldn't count on fairing nearly as well with the subequent forced landing as you will with the 182 when it's powerplant fails.

and if you dont like not having a driver door, best avoid flying most pipers or anything larger


Well, presently if I want to get out of the cockpit, it's either leave the seat, retire to the rear supernumary area and descend a flight of stairs to the main deck before leaving the main entrance door, or exiting the top hatch out of the cockpit and descending on an emergency cable about 38' to the ground. And no, I don't like not having a driver door. My other regular airplane has ejectable doors and quck release side panels, a full steel roll cage, and I usually wear nomex, gloves, boots, and a helmet.

The cherokee doors are a disgraceful joke and it applies from the PA-28 through the Seneca. It's a sorrowful piece of engineering.

However, seeing as you mentioned it, when I flew the Navajo, I had an exit door in the cockpit. It's a little bigger than a Cherokee, and it's still a piper. The Cheyennes we flew didn't have the door, but we figured we could plow over the station operator in back if we had to get out in a hurry :}.

bookworm
6th Jan 2008, 08:13
and it suggests to deal with the landing...

Both points true. I routinely land with half-flap. With full flap the window I described between ground attitude and stall is even smaller.

There's also a small-nose-wheel mod that has a similar effect to pumping up the main-wheel oleos.

Mach Tuck
6th Jan 2008, 13:13
Bookworm has it.

Basically, the Twin Comm's attitude on the ground is that of a shallow climb. Therefore, if the speed is not exactly right before the flare, rotating the aircraft into the landing attitude will cause it to climb away again or scoot off down the runway in ground effect until the speed bled off. The take off can be equally interesting for the same reason; slightly too much back-pressure on the stick and it gets airbourne in ground-effect at an alarmingly low speed, slightly too much forward pressure and the aircraft will wheelbarrow which can be quite exciting in a crosswind! Once you got it right though it was a very satisfying little aircraft to fly.

Back to the original question, though:
1. The venerable Aztec wins hands down for load-carrying, comfort, benign handling and airfield performance. Strangely, the older round nosed models (C and D) were slightly faster than the later pointy nosed ones.
2. The Twin Comanche doesn't have the load carrying capacity but has great economy, speed and range and will appeal to those who like a bit more of a handling challenge.
3. Then there's the Seneca. I only ever flew the Seneca I and never really understood why Piper bothered with it. Cobbled together from all sorts of bits they had lying around it fell somewhere between the Aztec and the Twin Com but without the appeal of either and the handling was just awful. I'm sure it will have improved with later versions, though.

Good Luck,

MT

AC-DC
6th Jan 2008, 21:34
Bookworm

Have you try the wing fillets: All reports say that they make the landings much smoother and more predictable.

bookworm
6th Jan 2008, 21:59
Have you try the wing fillets: All reports say that they make the landings much smoother and more predictable.

Though we got the VGs fitted only a couple of years ago, we've had the wing fillets since we got the aircraft. If they make landing significantly easier, I shudder to think how badly I'd land one without the wing fillets. ;)

TwinkieFlyer
7th Jan 2008, 14:41
The wing fillets help.
Pumping the main struts to 4" helps.
The small nose tire helps (15x600-6)
Putting 100# in the baggage helps alot.
Land with just a tiny bit of power, increases airflow over the tail
No flaps helps, but you need at least 900m for that

Don't ever try to lower the nose on a Twin Comanche if you over flare a bit, add power instead. The pitch is too touchy unless you have lots of experience.

deice
7th Jan 2008, 15:01
I'm just wondering, if the Seneca is such a crappy airplane as people seem to think, why are there so many of them? Agreed, the 1 is not perfect with it's aileron/rudder interconnect and heavy in the flare, but apart from that, what's so bad about it? It handles load rather well although it has poor SE performance but then what light twin doesn't (honestly) with only 200 hp normal aspirated per side? It's a benign twin at that, I've flown it below Vmc on one engine and it didn't kill me, the Duchess apparently is not so nice for example.
The Twin Co is apparently impossible to land properly and the Aztruck is only good for hauling a lot and burning tons of fuel.
Ok, so the Seneca 1 is not so fast, but with the 2 they sorted most of the problems and it's a pretty good airplane as compromises go. Is it not one of the most built twins around?

whitus1
7th Jan 2008, 18:16
Seneca would do the job nicely:ok:

AC-DC
9th Jan 2008, 13:48
It handles load rather well although it has poor SE performance but then what light twin doesn't (honestly) with only 200 hp normal aspirated per side?

Twin Comanche Miller convertion.

The Twin Co is apparently impossible to land properly

Also not true, it just take many Attempts.;) You should be able to make 6 good out of 10.

Contacttower
12th Jan 2008, 14:09
Also not true, it just take many Attempts.;) You should be able to make 6 good out of 10.

Well I'm getting a little better...still rather 'three pointer' though unfortunately...

bookworm
12th Jan 2008, 16:11
Well I'm getting a little better...still rather 'three pointer' though unfortunately...

Just remember this "any landing you walk away from" stuff is rubbish. They can carry you away and it still counts...

Irish Steve
29th Jan 2008, 00:57
Some time back, but .........

Did all my twin training, as a very low hours PPL, on the PA39 (non turbo) version of the Twin Com. It was my aircraft, and due to my very low hours at the start, it was a handful, but great fun, and (VERY important) with the right instructor, it is NOT a problem to fly accurately, but it has to be flown. The circuit at a small GA field can be 'interesting' as the best speed with the TC is around the 110 - 120 kts, ( due to the single engine blue line speed of 105 Kts) so if there are 3 or 4 Cessna 150's in the circuit, that calls for some careful planning, and more than a little changing of the order, and keeping the options open until shure of getting in adds some spice to getting rid of 30+ Kts of airspeed on very short final.

Went on to do IMC & night and then did a load of hour building/business flying (250 Hrs over a couple of years) all over the place in Europe, and for that, it was perfect, fast cruise, economical, and with De Ice and a reasonable panel, it would go pretty much anywhere I wanted, and when I wanted.

At the end of the training, and yes, we did a LOT more than the book says is needed for a twin, night & IMC rating, I was comfortable, and safe flying it single crew, at night, sometimes IFR on sectors of up to 3 Hrs 30 if needed, but a lot of that was down to an instructor that insisted that I fly it to IR standard, even though I couldn't do the IR initially as I didn't have enough P1 time, so had to stick to IMC rules for a while.

Did some flying in an Aztec during that training period, due to an annual getting in the way. Instructor's comments 'You're used to the TC, which is a bit like a Ferrari. This is the Land Rover of the range, and he wasn't far wrong. Big tank of an aircraft in comparison, much more expensive to operate, but would go places that the TC wasn't really suited to, like short grass strips and the like.

Flew Seneca 1 & 2 in the States when doing some more business trips, and then did my CPL/IR ratings in an old Seneca 1. It wasn't hard to fly in all fairness, but it was again, more expensive, slower than the TC, but capable of carrying a lot more weight.

As a real fun go places reasonably fast and economically airplane, with a relatively light load, the TC was great. Despite the comments above, the TC can be landed 'nicely', a trickle of power, nail the speed, and it's not dramatic. Get the speed wrong, either way, and it can be 'interesting'. Trimming is critical, ( electric trim is almost an essential for workload reduction, especially for single engine work) and the all moving elevator means that it's incredibly sensitive in pitch.

You won't carry 4 adults and bags very far, even with tip tanks, but at 160 Kts or better, that may not be a problem. Even 2 adults and 2 children with bags may require a bit of care with the w & B, and it's not going to work with full tanks. One or 2 up, the only restriction worth considering is the bladder endurance, mine with full tanks and tips filled was good for nearly 11 hours if it was set up correctly in the cruise. The handling is very different 2 up to 6 up, the instructor demonstrated that to me by getting me to do a (short) trip with it loaded on one occasion, and it makes a huge difference to the handling, as the C of G is much more aft. Worth doing if you're getting a TC.

The Aztec is a work horse, and the one I flew wasn't going to set the world on fire speed wise.

The Seneca is sort of between the 2. The rudder/aileron couple can cause problems if you don't keep your feet firmly on the rudder pedals when cruising, in that it can cause some very uncomfortable fish tailing for the people in the back row if there's a bit of unstable air causing the aircraft to twitch, unless it's blocked, the rudder couple upsets things as the ailerons are used to correct the course. Other than that, it's a genuine enough slightly larger twin that can haul 6 adults a reasonable distance without having to keep stopping for fuel.

Hope that helps a little

Steve

bookworm
29th Jan 2008, 07:54
The circuit at a small GA field can be 'interesting' as the best speed with the TC is around the 110 - 120 kts, ( due to the single engine blue line speed of 105 Kts)

I think you may be misremembering that. Vyse is 91 KIAS on the PA30/39 (which is 105 mph). Although it's not as pleasant to fly at 95 KIAS, it is a reasonable speed to fit in with slower traffic.

Contacttower
29th Jan 2008, 18:55
Great that we have a few Twin Com drivers here because I was wanting to ask another question...

I've just finished the MEP on the Twin Com but I'm slightly in two minds about the take off technique. According to the AFM:

Take-off technique

With flaps 15 and both engines at maximum take-off power, the aeroplane should be held on or near the ground until the take-off safety speed of 97mph is attained.

I've been told by my instructor not to use take off flap (this is for a hard runway) and to rotate at 85mph...which as you can see differs slightly from the AFM.

What do others do?

bookworm
29th Jan 2008, 19:25
With flaps 15 and both engines at maximum take-off power, the aeroplane should be held on or near the ground until the take-off safety speed of 97mph is attained.

I have a theory about this one.

The PA30 was involved in a number of training spin/stall accidents in its early days when the FAA still required a Vmca demonstration in checkrides. The problem was, in essence, that the rudder remained effective down to speeds very close to stall, and the Vmca demo rapidly turned into an asymmetric stall.

The "fix" was straightforward: the FAA simply increased the nominal Vmca, by a fair few knots. As a result, the take-off safety speed increased proportionately, but, I hypothesise, the instruction in the POH remained the same with the new figure inserted. Perhaps it was test flown a couple of times on a nice day.

As a result, the instruction is, IMHO, dangerous in many conditions. The high nose attitude on three wheels of the PA30 means that at 97 mph with flap 15 you're either climbing or you're wheelbarrowing. The unofficial Owner's Handbook for the PA30B (well worth getting a copy, Essco sell them) quotes take-off runs based on a lift off speed of 80 mph with flap 15, with an assumed speed of 91 mph at 50 ft.

I don't use flap for take-off, though I don't tend to operate off short runways. I lift off when the aircraft wants to lift, and accelerate to about 90 kt before tucking the gear away and climbing.

Contacttower
29th Jan 2008, 19:51
Thanks bookworm, the theory about Vmca had crossed my mind as well...but the AFM I have is from 1963 which is presumably before the FAA changed the Vmc figure from 80mph to 90mph. It may be that the manual I have is in fact a mix of stuff from different dates...it says 1963 on it but I know the plane is a 'B' model built in 1966 which is a bit bizarre, although it does have the plane's registration on it. So who knows about that?


The unofficial Owner's Handbook for the PA30B (well worth getting a copy, Essco sell them) quotes take-off runs based on a lift off speed of 80 mph with flap 15, with an assumed speed of 91 mph at 50 ft.


Actually I ordered one a few days ago...I'm glad you think it's worth getting. Although of course it is 'unofficial' it is still a Piper publication isn't it?

bookworm
30th Jan 2008, 07:26
but the AFM I have is from 1963 which is presumably before the FAA changed the Vmc figure from 80mph to 90mph

but presumably the Vmca figure is amended nevertheless?

Although of course it is 'unofficial' it is still a Piper publication isn't it?

Yes. I find it useful.

Contacttower
30th Jan 2008, 11:14
but presumably the Vmca figure is amended nevertheless?


:hmm:...On closer inspection the AFM lists under amendments:

Revised minimum single engined control speed and take off safety speed, dated 7/7/64.

An identical amendment entry is also listed further down the page dated 12/12/69. The 1964 entry only amended the take off safety speed (to 97mph as written in the second paragraph of the take off technique section) but the 1969 amendment also changed all the take off distance graphs. There isn't actually any mention of Vmca in the AFM as such, it mearly lists the 'recommended single engine maneuvering speed' of 97mph (despite the words 'minimum single engined control speed' appearing in the amendments page it doesn't reappear anywhere else in the AFM which is a bit odd I thought) which I take to be different from Vmca which I know to be 90mph.

What I had been expecting to find was a big added page which actually stated the change of Vmca from 80mph to 90mph like the AFM has for the Vne change of 230mph to 215mph. But like I said above, other than on the amendments list itself a reference to Vmca doesn't exist in the AFM.

AC-DC
30th Jan 2008, 22:03
The unofficial Owner's Handbook for the PA30B (well worth getting a copy, Essco sell them)

Bookworm
Why to buy an unofficial POH when you can get an official one? Call Webco and order your ICS POH. You are a member aren't you?;) You will find there more info than you think.

bookworm
31st Jan 2008, 17:10
I think we're talking at cross purposes AC-DC. The only "official" manual in the sense that I meant is the aircraft's Approved Flight Manual. ICS info tends to be excellent, but the Piper Owner's Manual is also helpful.

Contacttower
31st Jan 2008, 18:15
Call Webco and order your ICS POH.


Have you got one AC-DC?

I looked at it on the ICS website and was wondering if it was any good.

AC-DC
31st Jan 2008, 18:58
Yes I have it (2 if to be honest, one at home and one in the aircraft) and it is A*. Very very good with all the information that you might need. They are not cheap but worth every penny.

TwinkieFlyer
31st Jan 2008, 22:43
Please try to avoid taking off with Flaps in a Twin Comanche. They make it nearly impossible to lift off above Vmc. The later factory POH lists flap setings for TO at 0-15. Optional.

bookworm
1st Feb 2008, 08:04
Please try to avoid taking off with Flaps in a Twin Comanche. They make it nearly impossible to lift off above Vmc.

I found an even better reason once. The flaps are retracted by independent springs. So at 300 feet or so after take-off with flap 15, you command flaps up, and only one retracts. The aircraft remains controllable in that state, but it's not my choice of configuration on a high-workload departure. ;) (BTW, solution is to extend flap to 15 again, reduce airspeed, and retract again.)

AC-DC
1st Feb 2008, 20:24
I found an even better reason once. The flaps are retracted by independent springs. So at 300 feet or so after take-off with flap 15, you command flaps up, and only one retracts. The aircraft remains controllable in that state, but it's not my choice of configuration on a high-workload departure. (BTW, solution is to extend flap to 15 again, reduce airspeed, and retract again.)

Your way to solve the problem is correct but in order to prevent it from re-ocurring replace the flap rollers to the plastic type, available from Tony Brown, Webco and Piper. If you replaced them and the problem persist clean the tracks and make sure that they are not lubricated, keep them dry.

frog_ATC
1st Feb 2008, 22:00
Hello !

I flew only Seneca & TwinCo, not the aztek.
But I would say :


If you fly often enough to be "current", and want a nice speedy airplane, the twinCo is the best.
Yes, not easy to land ! :-) Just need the exact good speed and attitude, what a terrible flare ! And props kiss the grass, you have to be careful.
But that's a greaaat airplane, you will be charmed, the pannel is a mess and there are buttons and switches everywhere, but that smells "the good old fashion twin".
The one I flew was great because you could desactivate turbos manually, which allows you to do some training without stressing your engines.
Problem : de-iced TwinCos are very rare, so you'll probably have a non-deiced one.
Problem 2 : parts may be hard to find.


Seneca I : Great if you want to do some flight training because no turbo, but slow and a bit heavy.
Very reliable, a good transportation twin, easy to land, and a very comfortable cockpit. No Eurocontrol fees with the "below 2T" paper.
But most of them are getting old, quite a lot of flight hours done.
I would prefer the Seneca II turbo (we own one).
But recently built Senecas are too heavy and some even cannot avoid the eurocontrol fee !


Aztek : I never flew, a bit too thirsty, but Piper built reliable airplanes so I assume this one is also a good plane. Maybe parts problems.


About twins, I enjoy the DA42, nice trainer. Too slow and badly deiced for travelling 365 days/year, but nice baby (expensive to buy :-( !!).

Hope this will help...

Frog

Contacttower
26th Feb 2008, 20:25
Call Webco and order your ICS POH. You are a member aren't you?;) You will find there more info than you think.

Well, after quite a long wait, my ICS POH arrived and I am really pleased I got it. Not so much because it actually has much more information in it that the 'original', but because it is so much better laid out and doesn't have that 'home made' (lots of different photocopies of from different decades all bound together in a silly binder with a CAA stamp on it) feel to it that the 'official' one has.

Once again, thanks to all those who've answered on this thread. :ok:

gyrotyro
24th Mar 2008, 16:06
The Twin Com is easy to land, just remember the basics are the same as a single.

You probably arrived too fast as most new to the type do. Read the manual and fly the "V" numbers.

The safety speeds were increased some time ago after some single engine spin incidents at low level in the USA but the a/c was originally approved at lower "V" speeds.

Anyway if you approach at the recommended speed and flare correctly you should not float. Use the trim on finals.

I operate a PA30B out of 800 mts of grass strip and regularly fly in and out of a 600 mts grass strip.

PM me if you would like to talk it through.

Enjoy.. they are a great machine, 50 [email protected] 160 kts. Hard to beat. Even the DA42 can't fly that fast and costs 3 times as much.

ika
23rd Mar 2009, 22:39
I have a nice model E, having owned (and still flying a single Comanche, sold to a friend, flew last Saturday). The Aztec will get in and out of virtually anywhere (last weekend I and the owner of the Comanche went into a 500m grass strip normally used by microlights in the Aztec without any problems) and has a rugged undercarriage that doesn't mind bumpy grass. It's about the only twin that doesn't limit your options for strips compared to an average single (and outperforms many on short fields).
I actually found it more fun (although obviously less sporty in handling) than the single Comanche to fly - it was a bit bumpy and the Aztec was much smoother. You can carry anything you like, 6 adults, full fuel, baggage (and lots of volume as well as weight capacity - I emptied the back of a large car full of luggage into it and took 4 kids and partner on holiday). Single engine is a non-event - I have just been talking to someone who recently lost an engine (cylinder detached) in his when 6 up on a warm day and calmly continued his flight to the maintenance airfield on one engine. I learnt MEP on a Seneca and found if you don't quickly pin the blue line, it goes down, whereas doing Multi-IMC renewal in the aztec was not so taxing - the docility and power is I think important for someone like me - a low time MEP pilot. As a single comanche owner, all I ever read was that the twins frequently bit unwary pilots. All I've ever heard about Aztecs is that they are forgiving. Someone might correct me but I'm pretty confident from what I've researched that there are relatively few accidents in Aztecs (not sure if that's true for Apaches) following a single engine failure and quite a few in Senecas and Comanches.
Downside is it's not that fast (I had 176 kts ground speed on Saturday at 13-14 us gph/side, generally cruise at about 160kts at 12 gph/side) compared to some others (B58, 310 which cost a lot more and need more runway) but unless you are regularly going on 400 mile trips the extra time is minimal compared to the time at each end. Some of them have very dated panels and whatever you spend on updating it, you are unlikely to change its value that much. I got one because it was cheaper than a Baron and I wouldn't now swap if money were not a factor. However, if you plan to confine yourself to respectable hard runways and do lots of long distance flying, you could spend a bit more on something faster.

Tinstaafl
24th Mar 2009, 23:43
The Aztec is docile - it has the same wing section as the Cub - however at max. weight it will bite you on one engine just as easily as a Seneca. Performance loss is still on the order of 80% so don't expect anything flash and *all* except in-line thrust types will turn turtle and spear in if you mishandle them asymmetrically.

Flight test/checkride conditions are usually misleading. They're almost never at max weight with only two up + fuel, and sometimes zero thrust isn't as close to slightly-less-than-zero as it should be. The more load capacity of the aircraft the greater the differential of training weight vs full.

much2much
26th Mar 2009, 18:30
DFC
aztec 4 seater. where's this from spent many hours (thousands) six up frieght up .iced up; in the70;s 80.s.lots of it legal public transport.wonderfull machine!:E