Author Topic: H-7/800 H-series as of 01/19  (Read 697 times)

Doug Johnson 1

H-7/800 H-series as of 01/19
« on: February 01, 2019, 03:27:13 PM »
The H-7/800 is probably considered the 8th production model of the Helios

                                                      ''H-7/800 H series''
Of the 18 ''H-7/800 H series'' 10 H-800s and 8 H-700s, built 12 are still around 4 H-700s and 8 H-800s and 1 incomplete H-800 now completed but not counted 66.67%, and of those 11 are located in the US, and 1 in Russia. 1

In ’82, An H-295, N68872 c/n 1474 was reregistered N700HC and converted to a preproduction prototype for the H-700 (Model number 700, is the doubled HP of the engine used). This was done by Tom Teufel (Helio Aircraft ltd) with Clarence Brent’s help. The FAA labeled it Project A7097-CE-DS. The "crash-cage/fuselage" was up-grossed to 3800 lb by replacing diagonals in the upper and lower bays of the fuselage with heavier wall tubing. A Lycoming 350hp TIO-540-J2B was installed. It was later returned to H-295 configuration. Although it hasn’t survived, I will place the History paragraph below.

The prototype to the H-800 was H-1 the first H-800 (again Model number, is twice the Hp of the engine used) built using the 8-cylinder 400HP Lycoming IO-720 engine. Although it hasn’t survived, I will place the History paragraph below.

The last 18 Helios completed were the "H-700 and H-800 series" in an attempt to restart the Helio Factory after 10 yrs by introducing an improved Helio model turned into a failure. There were to many untested innovations, and an increase to gross weight in both models. Both an attempt to improve the gear and by giving a choice of style, increased the weight, plus departure from the geared engines to heavier engines with increased HP decreased STOL performance.

The ''H-7/800, H series" is basically two versions of an upgraded "H-295" The H-700 with a TI0-540 Lycoming and the H-800 with an IO-720 Lycoming. The H-800 with the 400 hp eng had an inefficient prop unable to covert the entire 400 hp to thrust. Hartzell was in the process of designing a new 4 blade propeller for the GO-720 but the factory went out of business. It was also strengthened for about a 400 lb increase in useful load to 3800 without the use of an STC. It was also designed to be use conventional gear or trigear, and be easily placed on floats or skis. The aircraft was redesigned with a stainless-steel carry through spar to get rid of a recurring AD on the H-295. Starting with H-3 the upper wing attachment was redesigned to look similar to the lower wing attachment and increase the gross weight to 4000 lbs on takeoff 3800 lbs on landing. Both models were built with Cessna style laminated fiberglass main gear legs (used for expediency) because of inability to get the oleo gear legs in a timely manner. All in service have been upgraded to a sprung aluminum gear legs. A larger tailwheel 500:5 was available for the H-7/800 Helios. The Cargo door that opens to the rear was introduced to replace the utility door that opens upward. Personally I prefer the Utility door that lifts upward because if it comes open in flight it is a non-incident because if the utility door comes open in flight you just pull it down and latch it. When the baggage door that pens to the rear comes open in flight (and it has on at least one reported incident) you have to land and repair the damage. Also installed were the ugly wingtips designed by U of CO Aeronautics dept that were supposed to wing tip vortex and decrease drag but actually didn't have any effect.

There is no STC for an upgross to the H-7/800, 1 H-700 was upgraded to a turbine engine, and 1 was an incomplete H-800 that was completed as an H-295 then converted to a radial eng version then converted to a turbine. The H-700s have a cooling problem so for H-7 a more aerodynamic cowling was designed by moving the landing lts to retractable versions in the wings and with more efficient cooling baffling (STC SA2141CE my understanding is that it cured the problem and is a better, looking cowling. A couple aerodynamic speed mods were done to H-5 wheel pants and a more aerodynamic cowling with better cooling baffles and  by moving the landing lts to retractable version in the wings..

Below are the history paragraphs of the H-7/800s, H series still in service highlighted in green, the first two grayed out are the prototypes

« Last Edit: February 04, 2019, 05:40:15 PM by Doug Johnson 1 »

Louis

Re: H-7/800 H-series as of 01/19
« Reply #1 on: February 02, 2019, 06:25:40 AM »
.

tailhook

Re: H-7/800 H-series as of 01/19
« Reply #2 on: February 02, 2019, 07:48:43 AM »
N700AA in 2004 at Oshkosh.

Jason Stephens

Re: H-7/800 H-series as of 01/19
« Reply #3 on: February 02, 2019, 12:34:53 PM »
Louis' photo cracks me up.

Doug Johnson 1

Re: H-7/800 H-series as of 01/19
« Reply #4 on: February 03, 2019, 08:31:23 PM »
Had to do an edit. to the above information.

Louis said that he was taking a nap while waiting for the Helicopter.

Kevin Dunn

Re: H-7/800 H-series as of 01/19
« Reply #5 on: February 04, 2019, 08:28:07 AM »
Doug,

Do you (or anyone else reading this) know the details of why the prop wouldn't allow full use of the 400 hp on the 800?

Kevin

jmetzler

Re: H-7/800 H-series as of 01/19
« Reply #6 on: February 04, 2019, 08:45:59 AM »
What is indicating less than 400 hp? The TCDS indicates 400 hp at 2650 rpm.

Doug Johnson 1

Re: H-7/800 H-series as of 01/19
« Reply #7 on: February 04, 2019, 10:21:44 AM »
OK I know what the type certificate says. I also reworded my post.

When I talked with Robert Casebeer about  the Agplane he said that the prop used on the IO-720 on the Agplane, and the H-800 was not able to give the full thrust that the 400 hp was capable of.

Maybe I'm not repeating what I was told correctly. The way I heard what he said, was that part of the hp wasn't developing thrust just making noise.

He said that Hartzell was in the process of developing a four blade prop that was capable of using the available 400Hp and would give more thrust but the Factory went broke before the prop testing was completed.

If I am still saying it wrong or it is still misleading give me some help. I have edit capability and I will change the way it is worded.



« Last Edit: February 04, 2019, 10:28:53 AM by Doug Johnson 1 »

tailhook

Re: H-7/800 H-series as of 01/19
« Reply #8 on: February 04, 2019, 11:55:46 AM »
The Lycoming IO-720 was developed for the Ag market, James Cox President of Helio Acft. LTD came from that sector of the aviation world which is why he built the Rat'Ler. That was a very unstable platform for aerial spray applications and may very well explain it's demise.

The IO-720 is a 600 pound engine, first used on Ed Swearingen's Excalibur 800 conversions of the Twin Bonanza, and later in the Comanche 400.

Mr. RPM has some mods to Twin Commanders 500 Super Shrike, 680F/FP/FPL, but fuel burn is another issue, cooling for the back cylinders does not measure up to well, either.

The blades on the 400 HP Lyc. go supersonic at the tips @ 2650 RPM, that increases drag by a large margin. The John Deere cowling of the 800 did not help matters as it presented additional drag that did not provide adequate cooling to the rear cylinders. The other ill-fated Lycoming engine that did not produce its rated HP was the TIO-541-E1B4 top intake version used originally on the ill-fated Mooney M-22 Mustang, and later on the Beech 56TC turbo Baron and Model 60 Duke, at 2900 RPM these engines just could not make take-off power respectively. Hartzell could not come up with an acceptable blade design to match the high output of these fuel thirsty engines. 93 Turbo Baron's were built ending in 1971 in favor the Duke.
« Last Edit: February 04, 2019, 01:25:19 PM by tailhook »

Kevin Dunn

Re: H-7/800 H-series as of 01/19
« Reply #9 on: February 04, 2019, 05:23:30 PM »
Doug,

If we are talking about thrust, then I understand (I think) what you are saying. The prop on the H800 might not generate as much thrust as the IO-720 can produce, but that is not a function of horsepower, that means the prop is not as efficient as it could be. That would make sense why Hartzell was looking to design a four blade. 

I have a customer with a Comanche 400 who is scheduled for an annual next week. I checked the TCDS and the prop on it is not the same one as the H800. Who knows why. The IO-720 is a good engine in the right application. If you can put up with 22-25 gph from a non-turbocharged engine. But then again, guys who fly Helios and Comanche 400s don't do it because it makes economic sense. :-)

Kevin

Doug Johnson 1

Re: H-7/800 H-series as of 01/19
« Reply #10 on: February 04, 2019, 05:36:05 PM »
I reworded it up above as this;

"The H-800 with the 400 hp eng had an inefficient prop unable to covert the entire 400 hp to thrust. Hartzell was in the process of designing a new 4 blade propeller for the GO-720 but the factory went out of business."

Maybe with what Stephen posted about about the IO-720 someone gets it.

Any other suggestions for a simple reword.
« Last Edit: February 04, 2019, 05:45:04 PM by Doug Johnson 1 »

jmetzler

Re: H-7/800 H-series as of 01/19
« Reply #11 on: February 04, 2019, 07:32:44 PM »
I found this link that lets you plug in the various things needed to determine prop efficiency. http://www.warpdriveprops.com/propspd2.html Interestingly, if you plug in an 86" prop at 2650 RPM you get a tip speed of 678 PMH and mach .88, which is actually the sweet spot for the propeller. Maybe Helio didn't like it because of all the airframe and engine drag drag that was a reality, however, it doesn't appear to be a poor engine/prop combination.

Doug Johnson 1

Re: H-7/800 H-series as of 01/19
« Reply #12 on: February 05, 2019, 12:02:37 PM »
Jim, I read your post and went to the Ward drive prop calculator, and after thinking some more, remembered talking with Larry the MT rep.

I believe that I am still not wording what I was trying say properly. I think it is still about horsepower. I definitely remember
Robert saying Horsepower and thrust in relation to 3 blade vs 4 blade prop.

When I spoke with the MT guy Larry Schlasinger. There was still some question about maximum diameter, 96” prop or the 101” prop that was certified on the H-395. Larry said that for a 300 hp engine at the GO’s RPM. 96” might be the limit because of the wider cord needed to soak up the higher HP. He then explained that you needed a thicker blade with composite blades than with aluminum blades. He also mentioned composite blades are thicker and the prop calculators don’t plug this in. He then explained that the thicker blade reaches its Mach number at a smaller diameter like any airfoil because of the thickness of the blades not the width.

I remember talking about speed or the a/c having an effect on the efficiency but I can't seem to write anything that makes sense to me. 

But I suspect that even on an aluminum prop that the chord or width of the blades on a four bladed prop would be less and thus thinner. Which leads me to believe they would be probably be more efficient at using the 400 hp.

tailhook

Re: H-7/800 H-series as of 01/19
« Reply #13 on: February 06, 2019, 03:51:19 PM »
Here we have the latest MT install approved for the 690/695 Commanders

Much more quiet, improved climb rates, but loses TAS by 5 KTS. They are 94.5 inches in diameter.

Don't know what specs MT has in mind for GO-480 application to H-395/295. But my guess will be improvement in climb, cruise and noise footprint.

Stephen