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Effectiveness Of Dash 7 Spoilers + Engine Reverse?  
User currently offlineHappy-flier From Canada, joined Dec 1999, 299 posts, RR: 0
Posted (10 years 3 months 4 weeks 20 hours ago) and read 4204 times:

I have wondered for a while whether pilots use both engine reverse and spoilers when landing Dash 7s (depends on conditions, I guess), or usually one or the other. The reason I ask is that with four engines even in reverse idle, wouldn't the spoilers be rendered completely ineffective due to the disruption of airflow over the wings? I'm picturing the scenario and it has me curious.

OR ... do Dash 7s typically land at such slow speeds anyway, that deployment of all possible air-brake devices is rarely necessary?

I'd appreciate any insight. Thanks.


May the wind be always at your back . . . except during takeoff & landing.
13 replies: All unread, jump to last
 
User currently offline320tech From Turks and Caicos Islands, joined May 2004, 491 posts, RR: 5
Reply 1, posted (10 years 3 months 4 weeks 20 hours ago) and read 4139 times:

I haven't worked on the Dash-7, but the Dash-8 automatically deploys flight spoilers (and ground spoilers, before they were de-activated) upon touchdown. I suspect pretty strongly the -7 is the same. Reverse thrust is selected by the pilot to suit the situation, so it's entirely possible that both spoilers and T/R would be used.

The flight spoilers are located just inboard of the ailerons, and so wouldn't be affected by airflow from the engines.



The primary function of the design engineer is to make things difficult for the manufacturer and impossible for the AME.
User currently offlineWrenchBender From Canada, joined Feb 2004, 1779 posts, RR: 8
Reply 2, posted (10 years 3 months 4 weeks 18 hours ago) and read 4082 times:

If you look at the development of the DeHavilland Canada line
-2 Beaver,
-3 Otter,
-4 Caribou, no spoilers
-5 Buffalo, Spoilers for short field work
-6 Twin Otter, Spoilers on the 300S STOL Commuter
-7 Spoilers (DHC still thinking Short/STOL Ops)
-8 Spoilers again carryover from the STOL heritage.

For some reason the DHC design group was still thinking in terms of STOL performance and rough field capability during development of the Dash 7. Much like the 300S Twin Otters which didn't really need spoilers but they were designed and installed in anyway, it's just the way DHC did things. Too bad there isn't a design team out there to propose some capable new concepts for these so called Bush Planes (-2 thru -6).

WrenchBender



Silly Pilot, Tricks are for kids.......
User currently offline320tech From Turks and Caicos Islands, joined May 2004, 491 posts, RR: 5
Reply 3, posted (10 years 3 months 3 weeks 6 days 15 hours ago) and read 3580 times:

Yeah, I always thought that de Havilland missed the boat when they didn't design a Beaver / Otter replacement in the early nineties. Of course, they may have had other things to think about (strikes, bankruptcy, buy-outs, etc).


The primary function of the design engineer is to make things difficult for the manufacturer and impossible for the AME.
User currently offlineBeowulf From Singapore, joined Jul 2003, 735 posts, RR: 13
Reply 4, posted (10 years 3 months 3 weeks 6 days 12 hours ago) and read 3569 times:

Hi,

An interesting issue Wrenchbender brought up here. Is another manufacturer picking up from DeHavilland? Sooner or later these bushplanes need to be replaced? Are there other replacements out there? Moreover, the question is, is there a market for this bush planes?

Nick


User currently offlineYikes! From Canada, joined Oct 2001, 284 posts, RR: 1
Reply 5, posted (10 years 3 months 3 weeks 5 days 20 hours ago) and read 3520 times:

There have been only 124 Dash 7's built. One of which was a high-gross-weight version DH7-150-Ice Reconaissance model which was certified to a 47,000 lb GTOW (approximately).

One of the biggest drawbacks to the DH7's acceptance into the commercial market was its speed. At 220 KTAS it was slow. Very, very slow. In the meantime the DH8 and its PW100 engine was in the fast-track development stages. A lot of prospective buyers told DHC that if it could produce the DH7 airplane with the equivalent of a -65 engine (~1300 shp) they would consider its purchase. Enough hesitation existed to halt the DH7's production as PWC would not do the R&D necessary without sufficient up-front orders for its engines. A few years later, Shorts Brothers was able to make the necessary guarantees with the S-360 version. And so the engine was finally developed that would have made (or Could have made) the DH7 a commercial success.

I was lucky enough to have flown the type as well as the -150 IR. The short field capabilities of the type just aren't required anymore. At least on a regular basis.

The frontiers of aviation continue to fade into the past....



User currently offlineScootertrash From United States of America, joined Aug 2001, 569 posts, RR: 9
Reply 6, posted (10 years 3 months 3 weeks 5 days 20 hours ago) and read 3512 times:

You are right about the STOL performance not being required anymore... Or is it? Imagine the capacity improvements at large airports if STOL capable aircraft could use shorter runways.

Personally, I think these RJ's with jet-like runway requirements are the worst thing to happen to airports since the TSA (sorry- had to get a dig in there).

Scooter


User currently offline320tech From Turks and Caicos Islands, joined May 2004, 491 posts, RR: 5
Reply 7, posted (10 years 3 months 3 weeks 5 days 19 hours ago) and read 3511 times:

As far as replacing the old Beavers and Otters goes, think Cessna Caravan and Grand Caravan. The only reason they haven't taken over entirely is the huge price tag. It's still much cheaper to rebuild a Beaver / Otter than to buy a Caravan.


The primary function of the design engineer is to make things difficult for the manufacturer and impossible for the AME.
User currently offlineYikes! From Canada, joined Oct 2001, 284 posts, RR: 1
Reply 8, posted (10 years 3 months 3 weeks 5 days 19 hours ago) and read 3505 times:

No argument here with regards that prehistoric rendition called the TSA.

"They" just don't get it. And never (from my perspective) will.

STOL requirements are now few and far between. For those that do require it though, there are sufficient numbers of DH7's available. Unfortunately the -65 retrofit is not available.



User currently offlineSLCpilot From United States of America, joined Aug 2003, 592 posts, RR: 2
Reply 9, posted (10 years 3 months 3 weeks 1 day 22 hours ago) and read 3407 times:

-2 Beaver,
-3 Otter,
-4 Caribou, no spoilers
-5 Buffalo, Spoilers for short field work
-6 Twin Otter, Spoilers on the 300S STOL Commuter
-7 Spoilers (DHC still thinking Short/STOL Ops)
-8 Spoilers again carryover from the STOL heritage.


Are there any plans for a -9? And no list is complete without my favorite DHC....

-1 Chipmunk !


SLCPilot

Who, incidently, has never flown/been a pax on any DHC product...



I don't like to be fueled by anger, I don't like to be fooled by lust...
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17173 posts, RR: 66
Reply 10, posted (10 years 3 months 3 weeks 1 day 21 hours ago) and read 3409 times:

There are probably plans for a 9, but since the -8 is selling rather nicely...


Starlionblue, who has flown the Twin Otter and the DHC-8-Q400.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineATCT From United States of America, joined Mar 2001, 2349 posts, RR: 38
Reply 11, posted (10 years 3 months 3 weeks 1 day 19 hours ago) and read 3392 times:

Yea the Caravan is sorta an Otter replacement. But what mechanic can just sit down in the woods and fix up a 208 with a light misty alaskan rain and mud beneath him. That picture just doesnt come to mind, now a veteran Otter/Beaver, just seems to suit the theme better. Also the performance of the DHC's vs. teh Caravan still leaves something to be desired in the Cessna category. It is a great aircraft dont get me wrong, but the closest thing that Ive ever seen coming to a Beaver/Otter replacement was either the Helio (not really replacement but a similiar aircraft in performance) or that thing called the "Sherpa" which was like a super cub derived animal that i think had 8 seats built by a guy in i think Washington. I read about it in mayeb Mountain Flying or some magazine (1999/2000 area?). Anywho anyone got more info on that beast thatd be much appreciated. Ciao and keep the blue side up!

ATCT



"The way to get started is to quit talking and begin doing." - Walt Disney
User currently offlineWrenchBender From Canada, joined Feb 2004, 1779 posts, RR: 8
Reply 12, posted (10 years 3 months 3 weeks 1 day 19 hours ago) and read 3382 times:

As DHC no longer really exists, now part of the Bombardier group. I can't foresee a dash 9 (DHC-9) unless they breed a CRJ with a Q400 and get a STOL-RJ (wait a minute, isn't that a BAE 146 ?) the others that are now part of Bombardier are Shorts (skyvan) and Canadair (amphibs). The Canadair division is doing well with the amphibs, but the 415T is way to specialized to be considered a bush plane. Therefore owning most of their own competition I cant see a next generation bush plane coming out of Bombardier as long as they stay comitted to the CRJ and the Q400.
The demand in northern Canada and Alaska will always be for true bush planes, something that will operate on wheels/skis/floats from -40 to +30 (celsius) the closest competitor appears to be rotary wing A/C but they have range and temperature problems in direct comparison to bush planes. I have yet to see a Cessna Caravan on skis and the floats available are not the sturdiest things to put on an A/C.

WrenchBender

http://www.airtindi.com/
http://www.arcticsunwest.com/
http://www.arcticdata.ca/~adlairzf/
http://www.buffaloairways.com/ not really bush planes but a great site


Edited to add links to operators in Yellowknife NWT

[Edited 2004-09-01 03:06:03]

[Edited 2004-09-01 03:08:05]


Silly Pilot, Tricks are for kids.......
User currently offlineSllevin From United States of America, joined Jan 2002, 3376 posts, RR: 6
Reply 13, posted (10 years 3 months 3 weeks 1 day 15 hours ago) and read 3371 times:

It was less than "thinking STOL" than a failed "thinking ahead" idea.

The Dash-7 was designed around the idea of small, short "city centre" airports that would couple both noise and STOL issues. Toronto City airport and London City were the initial targets -- in fact, until the expansion at LCY I'm fairly sure only Dash-7's couple operate from there.

However, the idea never really blossomed and no further STOLports were built, at which point the slow speed and extra engines of the Dash-7 were nothing more than liabilities.

Steve


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