Did the Sparrow Hawk become the Sadler Vampire?

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orion

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The Sparrow hawk and the Sadler Vampire are two different designs that had no connection whatsoever.

Although it did fly, the SparrowHawk was a somewhat marginal airplane that needed redesign to correct a number of problems including empennage flutter, drive design and some less than sufficient structure. It was also underpowered so a re-engine program might have been necessary.

The design faltered and exchanged hands several times, being held longest by the same folks who owned the now failed NSI. During that period the project really went nowhere, the las time i saw it it was gathering dust in the corner of their shop.

About two to three years ago I heard that the Sparrow Hawk was sold but I don't recall to who. But in all that time it has not reappeared so I'm not sure of its current status.
 

Dauntless

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Thanks for the info, Bill. My son recently found an ad for the Sparrow Hawk inside the back cover of the Sept '85 issue of Kitplanes, and immediately pointed out, "Dad, this is just the configuration you've been jabbering about for years." (Or words to that effect... ;))

On a side note, he also asked me why this configuration never caught on with the flying public, where conventionally configured high- or low-wing tractors predominate. I didn't have a ready answer for him. It just happens to be my favorite configuration since pilot training...lo those many years ago.

I found a few photos of Sparrow Hawks on the web, but there is only sparse info available to casual searchers. Anyone who has more detailed info about this airplane, please to post it up here.

Thanks!
 

Dauntless

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I had a sudden inspiration to search on the n-number of the airplane in the photos (N5832M), and lo and behold, there is an NTSB report (plug in the n-number and set the initial search date to 1987).

Having lived in Ellensburg as a young man, and flown in and out of there numerous times over the years, I can well relate to the reports of windshear and turbulence. Don't mess with Mother Nature, y'all! ;)
 

orion

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Interesting to see those in flight pictures - my info, albeit dated, suggests that the program did not get that far. But i guess I do recall some marketing flights so maybe some of the design issues may have been corrected, at least to the point of allowing the plane to be flown for the photos.
 

Dauntless

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I got your PM...thanks Bill!

More digging on the web shows that three kits were shipped to the UK in about '86, and that one was completed and flown within a year or two of that. The other two are reported as having been returned to the US, though where and to what fate, I know not.

The NTSB accident reports that the incident aircraft (the same one shown in the photos) had 100 hours on it when damaged by turbulence, so yes...it obviously made more flights than one trip around the pattern.

Thanks again for your help and info! :)
 

WBNH

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I recall an '80's Kitplanes article titled "Prototype to Princess" about that plane blossoming into a good flyer...

...Might still have the issue if I fumble through my stacks...don't have a scanner though.
 

WBNH

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OK...I was a little off on the date. It's in the September 1988 Kitplanes (I bought this when I was 13 and somehow still have it...) and reading between the lines, Orion is right (as always).

Ken Armstrong flew the plane and wrote the article.

It appears to have been a work in process at the time of the writing, greatly refined over an alluded to earlier prototype, but the author gives a number of recommendations that could make it better - almost sarcastically at one point. I do like the note about the 4 sq ft baggage area being a good place to warm your lunch...it was tiny and ran 30 degrees warmer than the cabin.

The test ship flown for the article was initially powered by the HAPI 75 horse, but was refitted with a souped-up water cooled Rotax 532; usually 65-hp, but in this configuration gave 97-hp...but which was not being imported to North America by the then Rotax Monopoly...

A 90-hp Norton rotary, and Subaru conversions were being evaluated.

Due to 25 pounds of ballast in the nose for solo flying, it was nose heavy for the dual in the article. Numbers were typically docile, cruise 100, stall 30...could cruise at Vne 125 at full throttle...econo-cruise at 73. Stalls were mild, but spins were out as the prototype hadn't been "flight tested in that realm" at the time of the writing. Controls were stiff at speed, comfortable on approach at 70 mph. No flaps. Main wheel touchdown was abrupt. I think they were trying to be really kind in the article. It is possible to read between the lines and note they had a few gripes they didn't want to expose explicitly.

It also talks about a Certified version they were working on, as well as the company, Aero Dynamics, Ltd, having government contracts to produce parts for fighters.

Whether it was just not successful, or the company went under trying to certify a version...or just got fat and happy on government contracts and got out of lightplanes is unknown, to me. As far as I can tell, only two were built.

The article concludes, "At this point, the prototypes have passed the 'chick' stage and entered the 'hawk-let' phase. While the Sparrow Hawk is still undergoing flight evaluation and improvements, only time will tell if this aircraft with many innovations will be the answer to tomorrow's aviation trainer and commuter needs."

Time told.

It's pages 48 - 51, if you can get your hands on a copy.

I might try scanning it at work, but not sure if that's legal.
 
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Topaz

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The CG limitations get a lot of these designs. You just can't put two people side-by-side ahead of the CG and expect to fit inside a CG range from a reasonable configuration.

You'll note that the prototype in that excerpt was "ballasted for solo flight". That's the usual solution. The designer decides that he can deal with movable ballast, but the customers eventually decide its a hassle and throw it out in favor of carrying the wife's makeup bag. Then gets back in solo and finds the airplane out of the CG range aft. Most people just won't take the trouble to do the CG calc, however easy it may be. How many pilots do you know that do a W&B with every new set of passengers, baggage, etc? Or even look at the chart in the POH? Something like the SparrowHawk demands close attention to the weight and balance. Most pilots aren't willing to do that, no matter how much they should.

I love these pod-forward, pusher designs. But unless it's a one-off for yourself, they're only really practical as tandems, with the passenger on the CG.
 

mz-

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Why is it a mid wing? Wouldn't a low wing enable you to put the wing further forward and thus enable putting the passengers very close to the center of gravity? Would it then have too rear CG problems with the engine placement? Putting the battery at the nose wouldn't compensate?
 

Dauntless

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Why is it a mid wing? Wouldn't a low wing enable you to put the wing further forward and thus enable putting the passengers very close to the center of gravity? Would it then have too rear CG problems with the engine placement? Putting the battery at the nose wouldn't compensate?
Even though such a configuration can somewhat obscure the downward vision of the persons on board, I agree that this is probably the best solution for a two-seater. I have flown a variety of tandem airplanes, and none of them are much fun for the back seater.
 

Topaz

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Why is it a mid wing? Wouldn't a low wing enable you to put the wing further forward and thus enable putting the passengers very close to the center of gravity? Would it then have too rear CG problems with the engine placement? Putting the battery at the nose wouldn't compensate?
Yeah. It's hard to compensate for 200# of passenger with 25# of battery, even if its a couple of feet farther forward.

I'm not saying the configuration is inherently flawed from an aerodynamic standpoint, but rather that the majority of the pilot population has shown itself to be unwilling to do the kind of W&B dilligence necessary on a regular basis to keep such an airplane safe.

The other issue I didn't mention explicitly before is that ballast - almost necessary in an airplane such as this - is simply cutting into the useful load with no other payback. And you can't leave it behind anywhere. What if, on the other end, you want to take a quick flight in the configuration that needs ballast? Or fly somewhere with a passenger and then return solo? The ballast needs to be accomodated in two positions in the airframe to accomodate the likely crew/fuel/baggage scenarios, which means it's always there, sucking performance.

A tandem-seated two-boom pusher (look up Tinbuzzard on this forum for an example) is a lot more practical in everyday use. The pilot and fwd fuselage balances the engine and booms, while the passenger, fuel, and baggage (if any) sits on the CG. With the same pilot, W&B becomes almost a non-event.
 

lurker

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- ballast -
And you can't leave it behind anywhere. What if, on the other end, you want to take a quick flight in the configuration that needs ballast? Or fly somewhere with a passenger and then return solo? The ballast needs to be accommodated in two positions in the airframe to accommodate the likely crew/fuel/baggage scenarios, which means it's always there, sucking performance.
water could be used for ballast, is readily available most anywhere, and can be dumped if not needed.
 

Topaz

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Could be. Can you count on every Joe that buys the plane to fill or empty the water tanks appropriately for every flight in the thirty-to-fifty year life of the airplane, when most of them only do a W&B for their Practical or a really picky biannual? And what do you do if the airport at East Podunk has a broken faucet, and you have to leave solo?
 

lurker

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no argument from me. the need for ballast is (IMO) by its very nature an indication that there is a design problem. there is also no guarantee that "joe" will take care of his stuff, nor that water is available everywhere. but (again IMO) water could solve the *technical* question 99% of the time.

Could be. Can you count on every Joe that buys the plane to fill or empty the water tanks appropriately for every flight in the thirty-to-fifty year life of the airplane, when most of them only do a W&B for their Practical or a really picky biannual? And what do you do if the airport at East Podunk has a broken faucet, and you have to leave solo?
 

Topaz

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Yeah. I wouldn't necessarily eliminate a small ballast requirement from a one-off designed exclusively for myself, but I'd never do one for an aircraft to be sold. And even for me, I'd avoid it if I could. It's just one more thing that could go wrong, and I'm a passionate believer in the Prophet Murphy. :)
 
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