????不過最關鍵的也許不是它的飛行方式，而是它到底在何處飛。為了維持這么長的飛行時間，這種飛行器將在大氣層的最佳位置即所謂的對流層頂飛行。這個區(qū)域距海平面約65,000英尺（即12英里多），風速通常小于5節(jié)。泰坦的工程師稱，這個空域相對平靜，且遠高于湍流或其他會影響其飛行性能的惡劣天氣，Solara可以在其中飛上五年之久。對流層頂下的天氣會損壞普通飛行器，對Solara來說更關鍵的還在于，它會遮蔽太陽，因此在遠高于這種天氣的對流層頂飛行Solara就不易損壞。

????泰坦的工程師稱，由于這種飛行器機械結構簡單，同時還有足夠的太陽能驅動它長期運行，因此現(xiàn)在限制飛行時長的因素就只有電池了。而電池會隨著時間推移而逐漸老化，每隔幾年就必須更換。為了論證這個問題，公司現(xiàn)在用兩架五分之一大小的試驗機進行試飛——同時推遲了B輪融資——到明年春季或夏季時才會讓全尺寸機型上天。

????桑德斯表示，到公司交付首架飛機時——最快要到明年年底——太陽能板和電池技術也許已大幅提高，可讓飛機飛行時間更長或攜帶更大載荷。他說：“我們正為了這個目標致力于開發(fā)最簡單、最輕量化的解決方案，同時努力避免過分復雜化。這才是讓這款無人機物美價廉、同時能夠不間斷飛行數(shù)年的關鍵所在。”

????當然，泰坦能否成功，至少在美國很大程度上取決于聯(lián)邦航空管理局（FAA）是否允許這種飛行器在國家空域中飛行。目前允許無人機進入國家空域的管理規(guī)定還未出臺（相關制度將于2015年推出），針對像Solara這樣大型無人機的管理制度應該會非常嚴格。

????不過桑德斯及公司對此并不怎么擔心，因為在該機型的設計研發(fā)全程中泰坦都與聯(lián)邦航空管理局保持著密切合作。而從技術上說，雖然這個機型的飛行壽命長達數(shù)年，但聯(lián)邦航空管理局真正關心的只是其最初爬升的那一段。桑德斯稱，美國的A級空域最高到60,000英尺為止，超過高度就不是聯(lián)邦航空管理局管轄的范圍了（這個高度大概是民用飛機飛行高度的兩倍）。

????桑德斯談及這家年輕的公司（桑德斯32歲，創(chuàng)始人兼首席技術官馬克斯?雅尼35歲左右，首席運營官尼克?雷諾德只有24歲）時表示，盡管符合現(xiàn)行飛行管理規(guī)定勢在必行，但這不是泰坦公司真正的動力所在。這就是為什么公司稱其產品為大氣層衛(wèi)星而不是無人機的緣故。在某種程度上，泰坦是要拿出一種截然不同、比現(xiàn)有產品更容易使用的產品來沖擊無人機和衛(wèi)星領域。

????桑德斯說：“我們不希望它帶來任何運行成本，不想客戶為了讓一臺不像樣的飛行器獲準飛行而不停地大筆花錢?！?/p>

????“我們想打造一臺非常簡單的產品，它能持續(xù)飛行，無需占用客戶大量時間和精力。如果只需要有一個人監(jiān)控飛行器，那就會讓局面徹底改觀。我們是要努力改變大家對飛行器運行方式的普遍看法?！保ㄘ敻恢形木W）

????譯者：清遠

????But perhaps the most important part of the formula is not how it will fly, but where. To sustain such long flight durations, the aircraft will operate in an atmospheric sweet spot known as the tropopause, a zone at roughly 65,000 feet (or more than 12 miles) above sea level where winds are generally less than 5 knots. In this relative calm far above any turbulence or weather that would otherwise challenge its flight capabilities, Solara could linger for up to five years, Titan engineers say. It doesn't hurt that the tropopause resides far above the weather that can damage conventional aircraft or, more critically for Solara, block out the sun.

????With rather simple mechanical systems and enough solar power to run them indefinitely, the thing limiting flight duration right now is the batteries themselves, Titan engineers say, which deteriorate over time and must be swapped out every few years. To prove it, the company has two fifth-scale test aircraft currently conducting test flights and -- pending a round of Series B funding -- will have a full-sized prototype in the air by spring or summer of next year.

????By the time the company delivers its first aircraft -- which could happen as soon as the end of next year -- solar cell and battery technology may have improved such that the aircraft can extend their flight durations or carry even more payload, Sanders says. "We're focusing on the simplest, most lightweight solution for this and trying not to get overly complicated," he says. "That's really the key to keeping this thing affordable as well as to enable it to stay up there for years."

????Of course much of Titan's success, at least in the U.S., hinges on the FAA clearing the aircraft to fly in the national airspace. While rules governing UAS integration into the national airspace are pending (delivery of a regulatory framework is slated for 2015), the rules attached to larger UAS like the planned Solara are expected to be fairly strict.

????But Sanders and company aren't particularly worried. Titan has been working closely with the FAA through its design process, and anyhow the only part of that multi-year duration the FAA is technically concerned with is the initial climb. Class A airspace ends at 60,000 feet in the U.S.; above that the FAA doesn't regulate, Sanders says (that's roughly twice the altitude that commercial airliners operate).

????But while fitting into the existing flight paradigm is necessary, that's not really the driving idea behind Titan, Sanders says of the young startup (Sanders is 32, founder and CTO Max Yaney is in his mid-30s, and chief operating operator Nick Renold is 24). That's why the company refers to its products as atmospheric satellites rather than UAS. In a way, Titan is trying to hack the UAS and satellite space by providing something radically different and far more accessible than what's already out there.

????"We don't want any operating costs, we don't want you to spend thousands and thousands and thousands of dollars just to get the stupid thing certified all the time," Sanders says.

????"We want something very simple and that doesn't take up all of your time and energy to keep it running. If all you need is one person to keep an eye on the aircraft, that completely changes things. We're trying to change the mindset on how aircraft should operate."

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