# Tillotson 212cc and 225cc on efficient ultralights?

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#### patrickrio

##### Well-Known Member
Bloop is cool but won't even be close to the mission reqs for a test pig (test piglet?)

Of course, I did an HBA search and found a bunch of threads on the American eaglet, even some already talking about putting a propeller around the tail boom.

You guys are already on this stuff.....

Edit, and also talking about it needing more wing area...and talking about how it's handling sucks... no original ideas in my head it seems....

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#### Daleandee

##### Well-Known Member
If you got 15 HP you can build a Whing Ding 2 that was designed by Bob Hovey:

#### WonderousMountain

##### Well-Known Member
On the subject of tails, I recommend the inverted Y.
It does not need mixers & has positive stability under
a down-lift condition. Equal proportions usually suffice.

If you have a low climb rate, might

~CK LuPii

#### patrickrio

##### Well-Known Member
Wing Ding 2 above looks like a great plane if you have a back yard big enough for a little air strip... just go up and fly a few circles around the patch...

It doesn't meet the speed requirements of what I think would be cool. The one I am thinking about could either have a folding prop for a self starting and sustaining part 103 glider that could go a long distance in a day. OR it could be fitted with a large diameter fixed or variable pitch prop for going long distances powered. Either one, being basically glider tech, could fly higher and faster while keeping under the 103 speed limit. Might ALMOST be ok for even longer distances.

I have been looking around, and the American Eaglet really seems to have one of the simplest design styles that meets the criteria. Too bad it is bad tempered in flight.

Another aircraft with a layout I think is good is the SunSeeker solar powered glider. Just the layout, which is essentially a faster version of the MuscleAir 2 human powered airplane. The propeller tech on the sunseeker is interesting also. 8 ft diameter variable pitch prop designed to rotate at about 400 rpm and has take off power of only 7HP (must be really anemic climb rate though....). I think the prop would be better rotating about the boom about 2 feet behind where the pod ends though....total TLAR thinking at the moment.

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#### reo12

##### Member
9-10 hp is simply foolish. It might work to get off the ground but there is no reserve climb capacity. Power loss from altitude density and inability to climb as fast or faster than sinking air will easily put the plane in a lack of climb - or easily - loss of altitude. Should this occur at the wrong point in take off or bad location and one could easily end up in the trees or power lines.

I watched a friend have this happen with a Lazair equipped with a pair of Pioneer engines. He was unable to outclimb terrain on a damp, foggy morning.

I used to make prop hubs for military standard engines. I talked with a gent once who put a 16 cu/inch 2 cylinder on a trike. This engine made right around 8.5 - 9 hp in the configuration it was in. The plane could not be flown on high altitude density days. I think he said he was never able to climb above 2000ft. He talked of a trip with a friend where he could not get above 450ft while he friend was at 2000ft. He had a number of times where sinking air would bring him down to the tops of the crops in the fields or the woods. Once - it did so where he could not climb above the trees in the fence rows that boxed the field. He was forced to fly circles waiting for the sink to subside for a moment when he was in the right part of the field to hop over the trees. He decided to stop flying the engine.
He laughed of the flights being so marginal. He knew he'd tickled the tail of the fate's dragon and been lucky to fly another day.

#### Taylor.S

##### Well-Known Member
Using two or three engines seem to be the best option. The less hp you try to push through a small engine the longer it will last and the cooler it will run.

#### nickec

##### Well-Known Member

You need to go faster.

Like the first iteration of the Colomban Cri Cri.

Engine horsepowers quoted in the table are for one engine, so double them, since the Cri Cri has two engines in every version.

#### Daleandee

##### Well-Known Member
9-10 hp is simply foolish. It might work to get off the ground but there is no reserve climb capacity. Power loss from altitude density and inability to climb as fast or faster than sinking air will easily put the plane in a lack of climb - or easily - loss of altitude. Should this occur at the wrong point in take off or bad location and one could easily end up in the trees or power lines.
Many moons ago I was considering a Challenger 1 with the 28 HP Rotax engine on it. My instructor at the time warned against it for the very reason you state. He said such low power would leave me in the trees when I couldn't out climb some serious sink on a hot Carolina summer day. Since those days experience has proven that he was correct.

I owned a VW powered Sonex for a number of years and a couple hundred hours. I flew it from SC to TN a couple of times and while lightly loaded with just me and my overnight bag, flying in the cool morning air in October, it would do OK. But put two people and enough fuel to go somewhere (never mind the luggage) on the same warm & muggy Carolina day and you had to pick your feet up when you went over the trees at the end of the runway.

Personally, I like to fly planes that climb better than they glide ...

#### patrickrio

##### Well-Known Member
OK. So flying on a single 9+HP engine is an idea of a goal, maybe one that is not achievable. The IDEA would be to start with a known aircraft design and probably build a model of it with a small set of modifications to move toward an aircraft good for a test bed.

So, maybe you could take a Moyes Tempest, change the tail boom to carbon fiber, change tail to inverted v (maybe) build a propeller around tail boom with reduction to engine (some of this has already been done with a motor, see pic) and power it at 22 HP. That might be a first design goal.

For this first iteration, leave wing and pod on the tempest the same as original. then test this configuration in 1/3 scale model size before building full size.

Next stage of modifications may be to do an updated pilot pod with lower weight and higher safety.

Next stage Might be to do a new cantilever wing with carbon fiber pultrusions and carbon fiber D tube, wing now sized appropriately for new weight.

Last stage might be to re-engine appropriately for the new aircraft. If the 9+HP engine won't work, you don't put it on.

I think people assume I plan to start with that engine and put it on something that everyone already knows for a fact won't fly with it. That wouldn't be a good idea...

Also, before anyone starts tearing apart the above plan for the Tempest, realize that I used it as an example. I would prefer to find a starting airframe that already weighs less than the Tempest..... and maybe is already closer to a good starting point as a test bed.

We already know that it is possible to fly an airplane over the Rocky Mountains multiple times with 7HP in an airplane. The Sunseeker II did that in a plane with a gross weight of approximately 430lbs. What I would like to see is if a MUCH LESS EXPENSIVE and less finicky airplane can be built that can fly comfortably on a bit more HP.

We also know that a really inexpensive airplane can fly quite well and speedily on 22hp already. See the SkyPup.

So, using newer tech, and newly cheaper carbon fiber materials, can a cheap airplane be built that operates well on less HP than the SkyPup and maybe even approaches the efficiency of the Sunseeker? That is what I am thinking about. The Tillotson 9+HP is in this range and is an interesting engine because of it's price. SO it's an interesting goal.

The tempest motor is below.....

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#### patrickrio

##### Well-Known Member
You need to go faster.

Like the first iteration of the Colomban Cri Cri.
Or the Colomban Luciole or the Rutan Quickie, or the Spacek SD-1....... Yes, it looks like if you get rid of the low stall speed and low max speed requirements of part 103 some of the design gets simpler. I just decided I wanted to stay ultralight for now..... basically because I have a preference for an airplane that is more motorglider like.

The tech and cost improvements for carbon fiber can likely improve on the above class of aircraft as well.... but the engineering on those airplanes is pretty daunting to try to improve. That is another reason I think that the ultralight is a good place to work. I think that part 103 motorized aircraft have mostly not improved efficiency for about 30 years and I think there is some low hanging fruit there if new tech is applied. I think stealing some ideas from existing MicroLift gliders and maybe some of the newer rigid wing hang gliders and combining with newly cheaper carbon fiber will likely be enough to do it.

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#### ElectricFlyer

##### Well-Known Member
HBA Supporter
And maybe build the propeller to rotate around the tail tube so the prop diameter can go up for efficiency
There is someone doing that now -- couldnt find it to post.

#### patrickrio

##### Well-Known Member
There is someone doing that now -- couldnt find it to post.
Here is a HBA tread that shows a few versions of propeller around the tail boom on a Moyes Tempest:

Moyes Tempest Tailboom Motors

In addition, here is a pic of the GFW-4 motorglider tailboom motor

And also the tailboom motor on the sirius-C motorglider

All of these implementations are small diameter folding propellers that are designed for self launch of a glider instead of sustained operation at efficiency. Sustained operation at efficiency would move toward large diameter variable pitch at low RPM like shown on the back of the Sunseeker II in the photo from my previous post.

I know there are more of them, I would love to see them. I would like to see a gas engine version too.

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#### Vigilant1

##### Well-Known Member
It is worth considering that it is very likely this 212-225 cc 4 stroke engine will have a continuous HP capability well short of 9 HP. And, ief we build a draggy plane that is right on the edge of the engine's capability, then continuous HP is what we'll care about. The problem will probably be heat.
When fitted to airplanes and without the stock fan, these engines will only make the stock HP if cooling air of sufficient pressure is available to push air through their fins, and that there is enough volume. I suspect, at about 50 mph cruise speed, that pressure will be the sticking point.

Lycomings, Continental's, VW Type 1s: they all need 30cc per HP to have enough surface area to shed the heat at their rated power. Tipi is working with an engine that has 810cc and he believes he can produce over 30 HP continuous (so 27 cc/HP),. He has reason to believe this will work because he is doing testing and because it is apparently working with some other planes, but they cruise at 80mph+, so they have considerably more air pressure available than would be available at Part 103 speeds.

The Valley Engineering Big Twin and Big Bad Twin were 990+ cc engines that produced about 40 and 50 HP, respectively, for takeoff and climb. But, both engines were limited to 32 HP continuous due to heat shedding limitations. That's 31cc/hp, again in draggy, slow airframes mostly.

#### patrickrio

##### Well-Known Member
I have most of the tools or access to them for VW engines. I have helped rebuild several VW engines, and their more expensive German 6 cylinder boxer cousins. I am considering VW powered aircraft too (but full 4 cyl). But that would be a pretty standard direction if I take it, and I would mostly be posting with questions while building instead of before hand. It would be cool if there was a CF motorglider design that ran on VW power I could get plans for... but there really isn't much of that because the current low prices for CF materials is a very recent development. Maybe soon?

I am also considering just doing a standard Skypup for fun... although my ultralight flight experience is 3 axis ultralights so 2 axis flight is less exciting. If I went the Skypup direction I would probably just bite the bullet and buy one of the new 4 cycle paraglider motors coming out and enclose the cockpit.

This Idea is more of a mental exercise and is very interesting to me. It might be the kind of thing that you work on and iron out some ideas, but never actually fly. I do think that this engine is a bit too far to accomplish, but if you build something that improves on existing that would be interesting. I have experience with composites and have wanted to do some vacuum infusion work too. CF materials also are now pretty inexpensive, about the same as fiberglass when you take strength into account.

If there was an existing home built CF motorglider ultralight design I could get plans for I would probably start doing such a plane soon. That is very interesting to me.

#### Armilite

##### Well-Known Member
This guy is using (2) Clone GX200s (68mm x 54 mm) 196.1cc/15hp = 13cc to make 1 hp built for 15hp each and has No Overheating problem. So if you use a Small Block for Plane use, I would use 13cc x hp you want will give you an idea of what CC Engine you need. 13cc x 20hp = 260cc (GX270). You have Small Block Honda/Clones that go up to the GX270 and Big Block Honda/Clones based on the Honda GX340/GX390 Engines. The Harbor Freight Predator 301 is the Smallest Big Block Single that I have seen. Big Blocks have the HD 1.0" PTO. For Big Blocks, I would use 12.4cc. A 460 Single 458cc Dynoed 37.37hp@5000rpm. 458cc/37hp = 12.4cc

My thoughts on the Honda Gx200's suitability to re-power the Lazair

The Lazair is a good Platform to Test different Small Engines. It flew marginally on (2) 5.5 hp Engines = 11hp, and it flew better with (2) Rotax 185ULs rated at 9.4 hp = 18.8 hp, but flew even better with (2) Solo 210's rated, 15 hp each = 30 hp! With an MTOW of 450 lbs = 204.1166 kg / 10 kg = 20.41166 kw needed = 27.37249 hp needed. 27.4/2= 13.7hp each. MTOW 450 lbs - 210 lbs Empty Weight = 240 lbs - 30 lbs Gas = 210 lbs for Pilot! Avg Pilot today falls between 180 lbs and 235 lbs.

For planes to make Part 103 24 knot Stall Speed it has to be Max 254 lbs + 30 lbs Gas + with a 170 lb Pilot. The T-Bird I with a 277UL made Part 103. 28hp x 75% = 21hp. It makes 20.3hp@5250rpm. I would bet the T-Bird I Stall Speed is around 10.1hp@4000rpm to 12.3hp@4500rpm! It makes 15.1hp@4750rpm.

460 Single Dyno Test.