Aircraft Speeds

[Kirstey]

Hi!

Hope everyone is well and making better use of the VMC than I am at the moment!

what are people's opinions on flying aircraft en route above the normal cruising speed for any length of time given the right conditions?

For example the Cruise of a C172 is about 120kts Vne is 163kts. If conditions were right. What problems would I encounter flying for an hour Straight and Level at 145-150kts IAS?

This being from a Renters perspective rather than an owner.

Cheers!

[Vizsla]

If you rented it wet who cares if you firewall the throttle but I doubt you would get anywhere near those speeds. The A/c owners would not be over excited if they did some calculations from the log sheets.

[M14P]

Well, you'd probably have trouble retrieving the throttle from behind the instrument panel where you had to push it to go that fast.

Seems a bit pointless really. Why not rent a quicker aircraft?

[Hersham Boy]

Who cares? Maybe the next person to hire it!

I don't know about other types, but I reckon you would only get another 10kts-odd out of an Archer if you flew with throttle to the wall. Hardly worth it, I wouldn't have thought.

Vne is a structural thing as far as I'm aware - ie. stick a 172 in a dive and you will get there but certainly shouldn't exceed it. You ain't going to get there without gravity though!

[Kirstey]

More of a hypothetical question really, but even flying 130KIAS as opposed to 120 makes a difference on a trip to central spain!

Obviously renting a faster plane is the option. But most aerodromes which have numbers of flying schools only have 172s and Archers to rent out. I rarely see any "pokier" SEP about.

[vancouv]

I can't help feeling looking at things from a renters rather than an owners perspective is a tad selfish. If you burn more fuel than is necessary it will just put up the hiring charges for everyone, yourself included.

And I wouldn't be too happy to have the donkey stop one day because someone hasn't been treating it properly.

As M14P says, if you are worried about flight times, hire a faster aircraft. For longer flights an aircraft that costs more per hour but cruises faster can often work out cheaper in the end.

[BlueRobin]

A typically proonish off-the-wall question :D Hopefully, this is a more sound answer!

This is what it says in a copy of a POH, which I have in my possession:

"Throttle settings in cruise:

a) Whilst a moderate throttle setting will ensure the maximum range, an aircraft's speed is one of its main advantages.

b) When calculating the required throttle settings for a journey, the pilot will take into account the meteorological conditions and his/her own capabilities.

NOTE: When flown within limits there is no mechanical reason for not setting the throttle for a fast cruise."

So, why, why not?

1. Faster mean more fuel burn. Moderate means greater range.
2. School FIs can recommend settings like 2200 or 2300rpm. I wouldn't redline the throttle (ona fixed-pitch prop). 100rpm off for a fast cruise would be mechanically okay in the case of the a/c above
3. Your human capability of handling a faster speed.
4. Enviromental conditions.

Check the POH for engine handling/cruise tips. You have read the POH, haven't you? :hmm: ;)

[Kirstey]

Whats a POH then?

[Hersham Boy]

Pilot's Operating Handbook

[BlueRobin]

Someone call Eurotroll! :*

[stiknruda]

Interesting topic this!

In my aeroplane (180hp Lyc with fixed pitch prop)

2050 rpm gives me 120mph indicated

2400 rpm gives me 140mph indicated

2600 rpm gives me almost 160 ias

red-line 2700 gives me a gnat's above 165.


My biggest constraint is fuel - I carry 75litres useable - at 2050 I sip a miserely 30lph, at 2600 rpm I gulp 40lpm.

The (no-wind) sums are quite easy - 2050 gives me 2.5 hrs = 300 miles to dry tanks

At 2600 I get 300 miles to dry tanks! I just get drier faster!

Guess that Spain is going to be something like 8 or 9 hrs each way; 130 v 120 equates to an 8% improvement in performance which equals a true time saving.

An 8% performance improvement on an 8 hr trip works out as getting there 40 mins earlier! As you'll need to stop to clear customs, fuel, overnight, etc., those 40 mins really don't make much difference overall at the end of the day.

Nine years ago I took a C182 across Africa and back. It was 30 hrs flying - I was going through the same quandry then as you are now! I ran the engine at max range power setting - I didn't feel that it was being strained or overworked and the couple of hrs that I would have saved in flight time were eaten up by night stops, bureacracy, etc.

Hope that this helps!


Stik

[Monocock]

Before any more people add posts can I suggest they search Private Flying for "Pilot Assist Flying Camp" and judge who might be back!!!!!!

[Evo]

Monocock - Kirstey has been posting here for a while. Apart from an intense dislike of Lydd she doesn't usually post anything too outspoken :) or were you talking about someone else :confused: Stik's been here even longer... ;) :p

[Monocock]

I certainly wasn't speaking about Stik, he's a fellow agrarian!
:ok: :ok: :ok: :ok: :ok: :ok:

[Circuit Basher]

Does that mean you're both afraid of open spaces - if so, why's Stik spent so much of his flying life in open cockpits??!! :) :)

[stiknruda]

I think Monocock is referring to our mutual fear of water - this being the true reason neither of us hold float-plane ratings!:)

Recall Kirstey being feisty in the past - but assumed* that this was a genuine, if rather poorly thought through question!

*As I keep telling my employees, "Assumption is the Mother of all F@ck Ups"

Stik

[Monocock]

Being an agrarian does not mean one has a fear of open spaces or of water. I believe (and stand to be corrected) that it means "of agriculture".

[AerBabe]

Isn't it a star sign?

[Keef]

"Agrarian" is one who studies the soil.

"Agoraphobic" is one who is afraid of open spaces (the "agora" or market-place).

"AerBabe" is the star-sign.

Allegedly.

[stiknruda]

Agora means NOW in Portuguese, hmmm afraid of the present!

Actually afraid that this morning's forecast of rain from the west might preclude both planned aviation and agrarian activities!

Certainly not afraid of Aerbabe!!

Stik:D :D

[tmmorris]

I tend to find FI's recommend a lower cruise throttle setting than the POH anyway - maybe for the plane's sake, maybe to give newbies more thinking time. For example in the Warrior I was taught to cruise at 2300 in the UK but it was a US instructor who pointed out that the POH recommended 2350 - quite a noticeable difference, as it turns out. Indeed he carried the POH and referred to it to check cruise throttle, leaning, and expected airspeeds, something I've never known a UK FI to do.

Tim

[Dale Harris]

Funny, ain't it. Mr Cessna and Mr Piper created books to go with their aircraft. You'd think we'd look there first to find the answers which we seek. After all, they probably know the aircraft better than most of us........

[knobbygb]

POH - didn't actually see one of these until I went flying Stateside. Never had it mentioned to me during training in the UK - can understand why it may not be the first thing to come to mind when one has a question. Hmmm.. POH or PPRuNe?

Anyway, what's wrong with asking a question such as this? Surely it's human nature what faced with a 'thou shalt...' type scenario to ask 'ah, but what if I don't...' If people weren't inquisitive, we wouldn't be flying at all. Surely better to ask here than to just try it out and see what happens?

By the way, nice to see a thread staying on track as usual :D

[FlyingForFun]

What's wrong with asking a question such as this? The big problem with questions like this is that there is no definitive answer, it varies from one aircraft to another. The danger is that someone gives a "definitive" answer, which may well be correct for one, or even many, aircraft, then someone else takes that answer as gospel and applies it to an aircraft where it doesn't work.

Having said that, it's still a great thread!

FFF
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[Circuit Basher]

Stick / Single Appendage - sorry, never having met me, you're obviously not used to my sense of humour. I am perfectly familiar with the terms agrarian / agoraphobia and just liked the juxtaposition of the 2! [PS agrarian has an alternate meaning of 'Advocate of re-distribution of landed property', so we'll just refer to the pair of you as Robin Hood, shall we??!! ;)].

[Tinstaafl]

Caring for the engine by only using low(er) power settings? Load of crap. Cruise at whatever power setting the manufacturer approves. That's why they publish limits such as Max. Continous power, Max MP vs RPM tables etc etc

It's up to you to decide the trade off between time & range. Don't forget to lean...

An FI will often pick an arbitrary round figure to use. It reduces the workload for the (typically) highly workloaded student. A good instructor will make sure the student knows it's just one of a number of alternatives & will eventually have the student choose an appropriate one.