multiple engines on single engine designs

Help Support Homebuilt Aircraft & Kit Plane Forum:

Dana

Super Moderator
Staff member
The Space Shuttle could have been considered a self launching glider, but as one NASA official said, "If we called it an aircraft the FAA would have us painting numbers on it, so we call it a spacecraft."

I wonder how many Shuttle pilots had glider ratings? :think:

Dana

Topaz

Super Moderator
Staff member
I wonder how many Shuttle pilots had glider ratings? :think:

I know they all had glider *training*, at least at the beginning of the program. Later on, I think they decided the shuttle simulator aircraft (a biz-jet with a variable stability system and a means to operate the flaps so that the aircraft mimicked the shuttle's L/D) was enough training.

Of interest, I understand that the Scaled Composites SpaceShipOne (in which Mike Melville made the first "commercial/private" manned suborbital spaceflight) carried an AC as an Experimental (exhibition or special) Glider. It would be considered a motorglider and the pilots all had the appropriate Glider rating.

Armilite

Well-Known Member
I am looking for some thoughts on the idea of using a Cri-Cri type motor mount on some ultralights originally intended for single engine. Both pusher and tractor, the mount should work similarly on either adaptation, weight and balance concerns can be assumed.
=============================================================================

Blane, first you have to understand, a USA Part103 Ultralight, can only weigh 254lbs, carry only 5 Gallons of Gas, and have a Stall Speed of 24 knots. Most of these Old, so called Ultralights, did not meet them Spec's. So make sure what your looking at meets them Spec's. Most Ultalight's should fly with just 20-35hp, depending on Airframe used.

Some of these older Engines can be made to make more HP, and still be reliable. If people spent some time researching, they would see there is a lot of new Tech out today. Most true Ultralights can't use any thing bigger than a Kawasaki 440, or Rotax 447, both rated 40hp account of their Weight.

A Rotax 447(40hp at 6500rpms) used a 9.6cr (What do you think a bump up to 11.2cr would do for it)

A Rotax 377UL(35hp at 6500rpms) used 9.6cr
A Skidoo 377/380(36hp at 7000rpms) used 9.6cr

A Skidoo 380HO(48hp at 7000rpms) used 11.2cr
A Skidoo 380HO has been Dynoed making 57.26hp at 7000rpms(But no data on what they did to it)

A 277UL(26hp at 6250rpms) With just a better Tuned Pipe, made 30.4hp at 6250rpms. Skidoo made production Singles up tp 335cc. You can Bore and Stroke any of these engines, and some rasie the compression ratio to get more HP.

A 185UL(9hp at 5000rpms) I believe it used 9.4cr. A properly built, Tuned (62mm x 61mm)185cc engine should make 25-26hp at 6400rpms. It takes 7cc to make 1hp at these rpms. These old motors didn't really have good tune pipes, used low compression. The crank was the weak point of the 185UL. Make a better crank out of a 377 61mm crank parts, PTO/MAG ends. The engine has the (4) Holes on the case for an adapter plate for a gear drive.

There are many old Sled Engines that could be used for an Ultralight. Think of it this way, a 185(9hp) probably burns 1.0gph, a 277(26hp) probably burns 2.0gph, a 377(35hp) 2.5gph, a 447(40hp) 3.0gph, you only have 5 gallons to play with. Fuel Injection woud help gph.

blane.c

Well-Known Member
Supporting Member
=============================================================================

Blane, first you have to understand, a USA Part103 Ultralight, can only weigh 254lbs, carry only 5 Gallons of Gas, and have a Stall Speed of 24 knots. Most of these Old, so called Ultralights, did not meet them Spec's. So make sure what your looking at meets them Spec's. Most Ultalight's should fly with just 20-35hp, depending on Airframe used.

Some of these older Engines can be made to make more HP, and still be reliable. If people spent some time researching, they would see there is a lot of new Tech out today. Most true Ultralights can't use any thing bigger than a Kawasaki 440, or Rotax 447, both rated 40hp account of their Weight.

A Rotax 447(40hp at 6500rpms) used a 9.6cr (What do you think a bump up to 11.2cr would do for it)

A Rotax 377UL(35hp at 6500rpms) used 9.6cr
A Skidoo 377/380(36hp at 7000rpms) used 9.6cr

A Skidoo 380HO(48hp at 7000rpms) used 11.2cr
A Skidoo 380HO has been Dynoed making 57.26hp at 7000rpms(But no data on what they did to it)

A 277UL(26hp at 6250rpms) With just a better Tuned Pipe, made 30.4hp at 6250rpms. Skidoo made production Singles up tp 335cc. You can Bore and Stroke any of these engines, and some rasie the compression ratio to get more HP.

A 185UL(9hp at 5000rpms) I believe it used 9.4cr. A properly built, Tuned (62mm x 61mm)185cc engine should make 25-26hp at 6400rpms. It takes 7cc to make 1hp at these rpms. These old motors didn't really have good tune pipes, used low compression. The crank was the weak point of the 185UL. Make a better crank out of a 377 61mm crank parts, PTO/MAG ends. The engine has the (4) Holes on the case for an adapter plate for a gear drive.

There are many old Sled Engines that could be used for an Ultralight. Think of it this way, a 185(9hp) probably burns 1.0gph, a 277(26hp) probably burns 2.0gph, a 377(35hp) 2.5gph, a 447(40hp) 3.0gph, you only have 5 gallons to play with. Fuel Injection woud help gph.
Thank you for your reply. I wrote a paragraph but I was timed out and the content was dumped. I will try again later.

blane.c

Well-Known Member
Supporting Member
=============================================================================

Blane, first you have to understand, a USA Part103 Ultralight, can only weigh 254lbs, carry only 5 Gallons of Gas, and have a Stall Speed of 24 knots. Most of these Old, so called Ultralights, did not meet them Spec's. So make sure what your looking at meets them Spec's. Most Ultalight's should fly with just 20-35hp, depending on Airframe used.
sry tried to write again but again info got dumped because I had to re-login

akwrencher

Well-Known Member
Supporting Member
blane.c, if you are having trouble like that, try writing in a word type program and the just copy and paste to the reply box. that way no chance of it getting dumped. I havn't had to do this but I don't write many long posts. Some others however have made a habit of it and can save a lot of frustration. Hope this helps.

akwrencher

Well-Known Member
Supporting Member
Just type what you want in whatever typing program you have on your computer, highlight the text, and press the "c" key while holding the ctrl key. then go back to HBA page, put your cursor in the reply box and press the "v" key while again holding the ctrl key and it will all appear here. those are the copy and paste functions. I apologize if you already knew this, just trying to help and not sure what you where referring to needing to figure out. Copy and paste is also really handy for sharing links without having to re-type five inches of URL address.....

blane.c

Well-Known Member
Supporting Member
=============================================================================

Blane, first you have to understand, a USA Part103 Ultralight, can only weigh 254lbs, carry only 5 Gallons of Gas, and have a Stall Speed of 24 knots. Most of these Old, so called Ultralights, did not meet them Spec's. So make sure what your looking at meets them Spec's. Most Ultalight's should fly with just 20-35hp, depending on Airframe used.

Hello; I am trying to understand more about ultralights, and I ask questions to encourage discussion that helps me to understand it better. The principle differences that I currently see are mass (obviously) but to the extent that not having much mass under certain circumstances will require a more immediate response because of the lack of inertia than in a heavier craft, and engines because ultralights are principled by two stroke engines and my flying experience encompasses no two stroke time what so ever. A good friend of mine who is an excellent pilot told me a couple of decades or so ago that one of the things that caused problems with two strokes was other people (than yourself) flying them, They are less tolerant of abuse than say a Lycoming, and it is or at least at that time was best not to let others mess with your engine. I can see the logic behind this. On the other hand how do you train people to fly an ultralight with a two stroke engine … teach em in a Lycoming and cut em loose to fair as they might with there two stroke? Because ultralights and then by association two strokes are not regulated there are widely varying opinions about the way('s) to operate them. This has a large amount to do with exactly which two stroke you are talking about. Lean the fuel mixture on some of them and you will invite near immediate failure, others if you do not lean them (correctly) they will clog up and choke themselves or carbon and crud up the rings and cylinder causing increased maintenance and potentially other problems. This leads to widely varying opinions and statements in the forums, generally the person writing is correct for his/her application but assuming it is correct in all instances leads to a lot of misinformation for newer pilots to sort through.

Modifying older engine designs by raising the compression is not generally going to work very well by itself, often you will need to change the ignition timing as well and in some cases port timing too, and then you may need to run a higher octane fuel than previously needed. Add to that the fact that higher compression usually leads to more vibration, so either better dampening/isolation or heavier flywheels/counterweights or more usually some combination of both. This along with problems with the strength of the crank ie is it and the related components going to take the additional power loading and a myriad of other mostly minor but often irritating and sometimes more painful problems … not the road for me.

So following are some (not all) of the reasons I am more interested in multi-engine designs and designs that can be converted to multi engine. (1) During the “golden age of flight” engines were less reliable and many wise men put more than one engine on an airplane to increase the odds of one or more of them still making power until a suitable landing place could be arrived. Lets face it two strokes are less reliable than four strokes and therefor I would take counsel of wise men. (2) I am becoming increasingly aware through my studying of what is currently available in engines of the fact that 2 two strokes of approximately ½ the horsepower of a larger two stroke will have significantly less total mass than the larger engine. This lesser weight will more than offset any additional weight of mounting. (3) there is a wider selection of new and potential suitable engines for “ultralight refitting” nearer to twenty hp more or less than to 40 hp more or less and they cost less than ½ as much. I have found one source that for less than $5,050.00 will deliver to my home two brand new 23 hp aviation engines engines weighing 25 lbs each (50 lbs total) For example. (4) most of the designs if not all that I am looking at will stay aloft just fine on less than 23 hp which in addition to giving you single engine performance allows you to throttle back and take it easy on the engines, and have additionaly far to much drag to exceed 55 knots in level flight with 46 hp. (5) Multi-engine airplanes are cool and who doesn't like the look of a nice vintage aircraft ultralights included. Armilite Well-Known Member Blane: What Brand of Engines are these 23hp, 25lbs? With only 5 gallons to play with, I think your barking up the wrong tree. Using two engines is maybe good for more power on bigger planes, but if one fails, and they all do, sooner or later, what then? Most Twin Engine planes crash also account there over loaded for two engines power not one. USA Part103 Ultralights, also have a Full Power On Speed also, I don't rember it for sure, but I think it's 54knots/62mph. Not that anyone is checking! 2 Strokes, are only less reliable, because most people don't understand them, or are to lazy to maintain them right. 95% of the problems are human related. 4 strokes, also fail for the same human problems. Those same People, break down in their cars, boats, etc., also. Most of these older 2 Strokes were not built to make their max hp they could make at are rpms of use. It's call$, Rotax wouldn't have sold any new 377UL(35hp), 447UL(40hp), 462UL(52hp), 503UL(50hp), 532UL(60hp) 582UL(65hp) motors, if a 277 Single was Big Bored & Stroked to make more CC, like a Simonini Single Cylinder Ultralight Engine is today, 362cc = 44hp, 382cc = 48hp, 400.5cc = 54hp all on a 9.5cr, and 6500rpms. They All play the Numbers Game, CC/CI(Bore & Stroke), Compression, Carb Size used, to fluxuate the HP made. Rotax built a 43hp RV Single Cylinder motor clear back in the late 60's. Rotax built a 580/582(582UL) Sled Engine with Fuel Injection in the early 90's. We still don't have fuel injected UL motors. Most True Part103 Ultralights, like I said, fly well on 20-35hp.

Or just be crazy like some people, and jump in and go flying.

But I reccomend 10-15hrs of training.

blane.c

Well-Known Member
Supporting Member
I hope I can transition to ultralights in less than 10 hrs (it's a pride thing) but I was thinking of going up and getting my bi-annual in a lsa at the same time so I could exercise my cfi privileges. I used to say I could fly a boat anchor if you'd put a engine on it ... of course it was just the beer talking. To bad you are not closer I would by you a beer and a burger maybe?

blane.c

Well-Known Member
Supporting Member
This quite impressive 75hp motor run at 25hp for an Ultralight.
Yes a couple of the things I think that is going to be a problem at some point or more importantly be allowed somehow by regulatory modification for electric ultralights, is the fact that you need a motor with much more power available than you actually use for it to work properly and someway somehow we need more than 5 gallons of battery life.

Armilite

Well-Known Member
Yes a couple of the things I think that is going to be a problem at some point or more importantly be allowed somehow by regulatory modification for electric ultralights, is the fact that you need a motor with much more power available than you actually use for it to work properly and someway somehow we need more than 5 gallons of battery life.
===================================================
75hp motor was used at 25hp rating to make Batterys last longer. A Part103 only allows 254lbs. Part103 hasn't changed in 35+ years, so don't coumt on it. 5 gals get's most people 1-1.5hr of flight, 2 if your real lucky, with a reserve.

Armilite

Well-Known Member
=====================================================================
One thing I would caution about, is these small engines designed for ParaPlanes don't have to push/pull much weight, so they may work ok on them, but not so well on aiplanes. I would find someone using one on a plane to get there opion.

BJC

Well-Known Member
Supporting Member
I am looking for some thoughts on the idea of using a Cri-Cri type motor mount on some ultralights originally intended for single engine. Both pusher and tractor, the mount should work similarly on either adaptation, weight and balance concerns can be assumed.

Contrary to the popular belief that John Moody was the first to fly a powered ultralight, Homer Kolb had a three axis control ultralight flying in 1970. It waspowered by twin pusher engines. I don't recall the make of the engines, but they were along the lines of a go kart engine or chain saw engine. They were mounted on a "board" that extended across the airplane just aft of the pilot's seat. As better engines became available, he changed to a single engine.

BJC