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aviatecar
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STOL Performance Improvement By More Powerful Engine?

Tue Jan 02, 2018 9:17 pm

Hello Gurus:

DHC-7 is very impressive in terms of STOL. The biggest difference between DHC-7 and DHC-8 is probably the number of engines.

What do you think of fitting DHC-8-300 engines (2,380–2,500 shp PW123/B/E) into DHC—8-200 aircraft (2,150 shp PW123C/D)?
Will that be an easy way to improve the STOL performance? Or more aggressively, fitting -400 engines into -200? \

I understand there are lot other changes if engines are swapped so I am not going to do that lol. Just curious.

Thank you!
 
GalaxyFlyer
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Re: STOL Performance Improvement By More Powerful Engine?

Tue Jan 02, 2018 11:23 pm

First, huge structural problem, that and modifying a small fleet is likely very uneconomic. Then, there’s the Vmcg and Vmca problems of all that horsepower being controlled by a rudder never designed for the loads. Likely worse performance at huge cost. Next....

GF
 
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Balerit
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Re: STOL Performance Improvement By More Powerful Engine?

Wed Jan 03, 2018 6:37 am

More power is only really going to give you a better rate of climb, it's still up to the wing and lift devices whether you have STOL capabilities. Your airframe will still determine VNE speeds etc. You will also have better acceleration.
Licensed Aircraft Maintenance Engineer (retired).
 
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aviatecar
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Re: STOL Performance Improvement By More Powerful Engine?

Mon Jan 08, 2018 3:05 am

Thank you guys for the responses.

I guess I can imagine what a disaster it would be if someone actually trying to do that lol.

I understand wing design is critical to STOL performance and I realized that the dhc-7 wings are quite different from DHC-8 wings. Looks like there are more control surfaces!

So say, Bombardier is trying to develop a STOL aircraft to compete with C-295 then I think it easier to change wing design and tail design of DHC-8 than taking any other approach. is it?

Thank you!
 
GalaxyFlyer
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Re: STOL Performance Improvement By More Powerful Engine?

Mon Jan 08, 2018 3:50 am

[*]There’s very, as in no, demand for true STOL planes. Runways are everywhere, so anything bigger than a Twin Otter will have runways adequate long. I can say, without fear of contradiction, Bombardier will not build a new STOL plane without or without the DHC-8 as a basis. Viking owns the DHC-5 Buffalo cert and couldn’t find a market for a new production series.

GF
 
VSMUT
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Re: STOL Performance Improvement By More Powerful Engine?

Mon Jan 08, 2018 8:04 pm

GalaxyFlyer wrote:
Viking owns the DHC-5 Buffalo cert and couldn’t find a market for a new production series.

GF


Then again, the Buffalo was unpressurized, which hardly made it attractive.
 
GalaxyFlyer
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Re: STOL Performance Improvement By More Powerful Engine?

Tue Jan 09, 2018 2:28 am

True, but I don’t a STOL mission requiring long range, high altitude flight, hence pressurization.

GF
 
oldannyboy
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Re: STOL Performance Improvement By More Powerful Engine?

Tue Jan 09, 2018 10:12 am

GalaxyFlyer wrote:
[*]There’s very, as in no, demand for true STOL planes. Runways are everywhere, so anything bigger than a Twin Otter will have runways adequate long. I can say, without fear of contradiction, Bombardier will not build a new STOL plane without or without the DHC-8 as a basis. Viking owns the DHC-5 Buffalo cert and couldn’t find a market for a new production series.

GF


Agree. There's hardly any demand left for rugged/STOL/unpaved flying, even in areas that were defined 'remote' less than 20 years ago, and whatever demand there is can easily be covered by the older frames still floating around among the ever decreasing number of specialized carriers operating in above described market...
 
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lightsaber
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Re: STOL Performance Improvement By More Powerful Engine?

Fri Jan 12, 2018 3:07 pm

oldannyboy wrote:
GalaxyFlyer wrote:
[*]There’s very, as in no, demand for true STOL planes. Runways are everywhere, so anything bigger than a Twin Otter will have runways adequate long. I can say, without fear of contradiction, Bombardier will not build a new STOL plane without or without the DHC-8 as a basis. Viking owns the DHC-5 Buffalo cert and couldn’t find a market for a new production series.

GF


Agree. There's hardly any demand left for rugged/STOL/unpaved flying, even in areas that were defined 'remote' less than 20 years ago, and whatever demand there is can easily be covered by the older frames still floating around among the ever decreasing number of specialized carriers operating in above described market...

That should be emphasized on how many more runways there are. Also, how many previous gravel are now paved and were stretched to accommodate longer missions.

Not to mention road networks have improved. Many areas that used to be a STOL flight are now a drive.

Now on topic, engine power decreases required runway length. As the go/no-go decision is made with an engine out, 10% more power changes when the decision is made. So the added power will cut runway requirements. Just as better brakes can shorten the required runway length based on the certified rejected takeoff.

But is there a market? Planes are expensive and new designs must sell in quantity to pay back certification costs. There is a movement to cut certification costs, but the traction isn't there.

Lightsaber
You only have the first amendment with the 2nd. If you're not going to offend someone with what you say, you don't have the 1st.
 
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aviatecar
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Re: STOL Performance Improvement By More Powerful Engine?

Sat Jan 27, 2018 5:49 pm

lightsaber wrote:
oldannyboy wrote:
GalaxyFlyer wrote:
[*]There’s very, as in no, demand for true STOL planes. Runways are everywhere, so anything bigger than a Twin Otter will have runways adequate long. I can say, without fear of contradiction, Bombardier will not build a new STOL plane without or without the DHC-8 as a basis. Viking owns the DHC-5 Buffalo cert and couldn’t find a market for a new production series.

GF


Agree. There's hardly any demand left for rugged/STOL/unpaved flying, even in areas that were defined 'remote' less than 20 years ago, and whatever demand there is can easily be covered by the older frames still floating around among the ever decreasing number of specialized carriers operating in above described market...

That should be emphasized on how many more runways there are. Also, how many previous gravel are now paved and were stretched to accommodate longer missions.

Not to mention road networks have improved. Many areas that used to be a STOL flight are now a drive.

Now on topic, engine power decreases required runway length. As the go/no-go decision is made with an engine out, 10% more power changes when the decision is made. So the added power will cut runway requirements. Just as better brakes can shorten the required runway length based on the certified rejected takeoff.

But is there a market? Planes are expensive and new designs must sell in quantity to pay back certification costs. There is a movement to cut certification costs, but the traction isn't there.

Lightsaber


Makes sense. For the same airframe it needs to reach the same speed in order to take off. More power from engine means higher accelearation rate hence shorter runway requirement. But then again, many other aspect of the airfrme has to be changed and it is simply not feasible.
 
VSMUT
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Re: STOL Performance Improvement By More Powerful Engine?

Sun Jan 28, 2018 11:38 am

GalaxyFlyer wrote:
True, but I don’t a STOL mission requiring long range, high altitude flight, hence pressurization.

GF


I'm not so certain about that. Going forwards, STOL airstrips will be found more and more in hard-to-access locations, such as in mountainous or remote areas. For obvious reasons, anything easily accessible will be paved over with longer runways leaving just the places that can't be reached by construction machines, ergo the before mentioned mountains and remote areas. You can barely cross a decently sized mountainrange without pressurization.
 
GalaxyFlyer
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Re: STOL Performance Improvement By More Powerful Engine?

Sun Jan 28, 2018 3:24 pm

Lulka, Nepal seems well served without pressurized planes. It’ll be hard justify building planes for a market that specialized, as we see with none being built.

GF

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